In many cases, users might use DAMON for simple data access aware memory
management optimizations such as applying an operation scheme to a
memory region of a specific size having a specific access frequency for
a specific time. For example, "page out a memory region larger than 100
MiB but having a low access frequency more than 10 minutes", or "Use THP
for a memory region larger than 2 MiB having a high access frequency for
more than 2 seconds".
Most simple form of the solution would be doing offline data access
pattern profiling using DAMON and modifying the application source code
or system configuration based on the profiling results. Or, developing
a daemon constructed with two modules (one for access monitoring and the
other for applying memory management actions via mlock(), madvise(),
sysctl, etc) is imaginable.
To avoid users spending their time for implementation of such simple
data access monitoring-based operation schemes, this makes DAMON to
handle such schemes directly. With this change, users can simply
specify their desired schemes to DAMON. Then, DAMON will automatically
apply the schemes to the user-specified target processes.
Each of the schemes is composed with conditions for filtering of the
target memory regions and desired memory management action for the
target. Specifically, the format is::
<min/max size> <min/max access frequency> <min/max age> <action>
The filtering conditions are size of memory region, number of accesses
to the region monitored by DAMON, and the age of the region. The age of
region is incremented periodically but reset when its addresses or
access frequency has significantly changed or the action of a scheme was
applied. For the action, current implementation supports a few of
madvise()-like hints, ``WILLNEED``, ``COLD``, ``PAGEOUT``, ``HUGEPAGE``,
and ``NOHUGEPAGE``.
Because DAMON supports various address spaces and application of the
actions to a monitoring target region is dependent to the type of the
target address space, the application code should be implemented by each
primitives and registered to the framework. Note that this only
implements the framework part. Following commit will implement the
action applications for virtual address spaces primitives.
Link: https://lkml.kernel.org/r/20211001125604.29660-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rienjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Implement Data Access Monitoring-based Memory Operation Schemes".
Introduction
============
DAMON[1] can be used as a primitive for data access aware memory
management optimizations. For that, users who want such optimizations
should run DAMON, read the monitoring results, analyze it, plan a new
memory management scheme, and apply the new scheme by themselves. Such
efforts will be inevitable for some complicated optimizations.
However, in many other cases, the users would simply want the system to
apply a memory management action to a memory region of a specific size
having a specific access frequency for a specific time. For example,
"page out a memory region larger than 100 MiB keeping only rare accesses
more than 2 minutes", or "Do not use THP for a memory region larger than
2 MiB rarely accessed for more than 1 seconds".
To make the works easier and non-redundant, this patchset implements a
new feature of DAMON, which is called Data Access Monitoring-based
Operation Schemes (DAMOS). Using the feature, users can describe the
normal schemes in a simple way and ask DAMON to execute those on its
own.
[1] https://damonitor.github.io
Evaluations
===========
DAMOS is accurate and useful for memory management optimizations. An
experimental DAMON-based operation scheme for THP, 'ethp', removes
76.15% of THP memory overheads while preserving 51.25% of THP speedup.
Another experimental DAMON-based 'proactive reclamation' implementation,
'prcl', reduces 93.38% of residential sets and 23.63% of system memory
footprint while incurring only 1.22% runtime overhead in the best case
(parsec3/freqmine).
NOTE that the experimental THP optimization and proactive reclamation
are not for production but only for proof of concepts.
Please refer to the showcase web site's evaluation document[1] for
detailed evaluation setup and results.
[1] https://damonitor.github.io/doc/html/v34/vm/damon/eval.html
Long-term Support Trees
-----------------------
For people who want to test DAMON but using LTS kernels, there are
another couple of trees based on two latest LTS kernels respectively and
containing the 'damon/master' backports.
- For v5.4.y: https://git.kernel.org/sj/h/damon/for-v5.4.y
- For v5.10.y: https://git.kernel.org/sj/h/damon/for-v5.10.y
Sequence Of Patches
===================
The 1st patch accounts age of each region. The 2nd patch implements the
core of the DAMON-based operation schemes feature. The 3rd patch makes
the default monitoring primitives for virtual address spaces to support
the schemes. From this point, the kernel space users can use DAMOS.
The 4th patch exports the feature to the user space via the debugfs
interface. The 5th patch implements schemes statistics feature for
easier tuning of the schemes and runtime access pattern analysis, and
the 6th patch adds selftests for these changes. Finally, the 7th patch
documents this new feature.
This patch (of 7):
DAMON can be used for data access pattern aware memory management
optimizations. For that, users should run DAMON, read the monitoring
results, analyze it, plan a new memory management scheme, and apply the
new scheme by themselves. It would not be too hard, but still require
some level of effort. For complicated cases, this effort is inevitable.
That said, in many cases, users would simply want to apply an actions to
a memory region of a specific size having a specific access frequency
for a specific time. For example, "page out a memory region larger than
100 MiB but having a low access frequency more than 10 minutes", or "Use
THP for a memory region larger than 2 MiB having a high access frequency
for more than 2 seconds".
For such optimizations, users will need to first account the age of each
region themselves. To reduce such efforts, this implements a simple age
account of each region in DAMON. For each aggregation step, DAMON
compares the access frequency with that from last aggregation and reset
the age of the region if the change is significant. Else, the age is
incremented. Also, in case of the merge of regions, the region
size-weighted average of the ages is set as the age of merged new
region.
Link: https://lkml.kernel.org/r/20211001125604.29660-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20211001125604.29660-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Marco Elver <elver@google.com>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Greg Thelen <gthelen@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: David Rienjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently a plain integer is being used to nullify the pointer
ctx->kdamond. Use NULL instead. Cleans up sparse warning:
mm/damon/core.c:317:40: warning: Using plain integer as NULL pointer
Link: https://lkml.kernel.org/r/20210925215908.181226-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Just get the pid by 'current->pid'. Meanwhile, to be symmetrical make
the 'starts' and 'finishes' logs both use debug level.
Link: https://lkml.kernel.org/r/20210927232432.17750-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Just return from the kthread function.
Link: https://lkml.kernel.org/r/20210927232421.17694-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Cc: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Logging of kdamond startup is using 'pr_info()' unnecessarily. This
makes it to use 'pr_debug()' instead.
Link: https://lkml.kernel.org/r/20210917123958.3819-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Correct a singular versus plural grammar mistake in the help text for
the DAMON_VADDR config symbol.
Link: https://lkml.kernel.org/r/20210914073451.3883834-1-geert@linux-m68k.org
Fixes: 3f49584b26 ("mm/damon: implement primitives for the virtual memory address spaces")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Regardless of KFENCE mode (CONFIG_KFENCE_STATIC_KEYS: either using
static keys to gate allocations, or using a simple dynamic branch),
always use a static branch to avoid the dynamic branch in kfence_alloc()
if KFENCE was disabled at boot.
For CONFIG_KFENCE_STATIC_KEYS=n, this now avoids the dynamic branch if
KFENCE was disabled at boot.
To simplify, also unifies the location where kfence_allocation_gate is
read-checked to just be inline in kfence_alloc().
Link: https://lkml.kernel.org/r/20211019102524.2807208-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Initializing memory and setting/checking the canary bytes is relatively
expensive, and doing so in the meta->lock critical sections extends the
duration with preemption and interrupts disabled unnecessarily.
Any reads to meta->addr and meta->size in kfence_guarded_alloc() and
kfence_guarded_free() don't require locking meta->lock as long as the
object is removed from the freelist: only kfence_guarded_alloc() sets
meta->addr and meta->size after removing it from the freelist, which
requires a preceding kfence_guarded_free() returning it to the list or
the initial state.
Therefore move reads to meta->addr and meta->size, including expensive
memory initialization using them, out of meta->lock critical sections.
Link: https://lkml.kernel.org/r/20210930153706.2105471-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the new kunit_skip() to skip tests if requirements were not met. It
makes it easier to see in KUnit's summary if there were skipped tests.
Link: https://lkml.kernel.org/r/20210922182541.1372400-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
One of KFENCE's main design principles is that with increasing uptime,
allocation coverage increases sufficiently to detect previously
undetected bugs.
We have observed that frequent long-lived allocations of the same source
(e.g. pagecache) tend to permanently fill up the KFENCE pool with
increasing system uptime, thus breaking the above requirement. The
workaround thus far had been increasing the sample interval and/or
increasing the KFENCE pool size, but is no reliable solution.
To ensure diverse coverage of allocations, limit currently covered
allocations of the same source once pool utilization reaches 75%
(configurable via `kfence.skip_covered_thresh`) or above. The effect is
retaining reasonable allocation coverage when the pool is close to full.
A side-effect is that this also limits frequent long-lived allocations
of the same source filling up the pool permanently.
Uniqueness of an allocation for coverage purposes is based on its
(partial) allocation stack trace (the source). A Counting Bloom filter
is used to check if an allocation is covered; if the allocation is
currently covered, the allocation is skipped by KFENCE.
Testing was done using:
(a) a synthetic workload that performs frequent long-lived
allocations (default config values; sample_interval=1;
num_objects=63), and
(b) normal desktop workloads on an otherwise idle machine where
the problem was first reported after a few days of uptime
(default config values).
In both test cases the sampled allocation rate no longer drops to zero
at any point. In the case of (b) we observe (after 2 days uptime) 15%
unique allocations in the pool, 77% pool utilization, with 20% "skipped
allocations (covered)".
[elver@google.com: simplify and just use hash_32(), use more random stack_hash_seed]
Link: https://lkml.kernel.org/r/YU3MRGaCaJiYht5g@elver.google.com
[elver@google.com: fix 32 bit]
Link: https://lkml.kernel.org/r/20210923104803.2620285-4-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the saving of the stack trace of allocations into __kfence_alloc(),
so that the stack entries array can be used outside of
kfence_guarded_alloc() and we avoid potentially unwinding the stack
multiple times.
Link: https://lkml.kernel.org/r/20210923104803.2620285-3-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Maintain a counter to count allocations that are skipped due to being
incompatible (oversized, incompatible gfp flags) or no capacity.
This is to compute the fraction of allocations that could not be
serviced by KFENCE, which we expect to be rare.
Link: https://lkml.kernel.org/r/20210923104803.2620285-2-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This has served its purpose and is no longer used. All usercopy
violations appear to have been handled by now, any remaining instances
(or new bugs) will cause copies to be rejected.
This isn't a direct revert of commit 2d891fbc3b ("usercopy: Allow
strict enforcement of whitelists"); since usercopy_fallback is
effectively 0, the fallback handling is removed too.
This also removes the usercopy_fallback module parameter on slab_common.
Link: https://github.com/KSPP/linux/issues/153
Link: https://lkml.kernel.org/r/20210921061149.1091163-1-steve@sk2.org
Signed-off-by: Stephen Kitt <steve@sk2.org>
Suggested-by: Kees Cook <keescook@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Stanley <joel@jms.id.au> [defconfig change]
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E . Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmap_atomic() is being deprecated in favor of kmap_local_page().
Replace the uses of kmap_atomic() within the highmem code.
On profiling clear_huge_page() using ftrace an improvement of 62% was
observed on the below setup.
Setup:-
Below data has been collected on Qualcomm's SM7250 SoC THP enabled
(kernel v4.19.113) with only CPU-0(Cortex-A55) and CPU-7(Cortex-A76)
switched on and set to max frequency, also DDR set to perf governor.
FTRACE Data:-
Base data:-
Number of iterations: 48
Mean of allocation time: 349.5 us
std deviation: 74.5 us
v4 data:-
Number of iterations: 48
Mean of allocation time: 131 us
std deviation: 32.7 us
The following simple userspace experiment to allocate
100MB(BUF_SZ) of pages and writing to it gave us a good insight,
we observed an improvement of 42% in allocation and writing timings.
-------------------------------------------------------------
Test code snippet
-------------------------------------------------------------
clock_start();
buf = malloc(BUF_SZ); /* Allocate 100 MB of memory */
for(i=0; i < BUF_SZ_PAGES; i++)
{
*((int *)(buf + (i*PAGE_SIZE))) = 1;
}
clock_end();
-------------------------------------------------------------
Malloc test timings for 100MB anon allocation:-
Base data:-
Number of iterations: 100
Mean of allocation time: 31831 us
std deviation: 4286 us
v4 data:-
Number of iterations: 100
Mean of allocation time: 18193 us
std deviation: 4915 us
[willy@infradead.org: fix zero_user_segments()]
Link: https://lkml.kernel.org/r/YYVhHCJcm2DM2G9u@casper.infradead.org
Link: https://lkml.kernel.org/r/20210204073255.20769-2-prathu.baronia@oneplus.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Prathu Baronia <prathu.baronia@oneplus.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is one possible race window between zs_pool_dec_isolated() and
zs_unregister_migration() because wait_for_isolated_drain() checks the
isolated count without holding class->lock and there is no order inside
zs_pool_dec_isolated(). Thus the below race window could be possible:
zs_pool_dec_isolated zs_unregister_migration
check pool->destroying != 0
pool->destroying = true;
smp_mb();
wait_for_isolated_drain()
wait for pool->isolated_pages == 0
atomic_long_dec(&pool->isolated_pages);
atomic_long_read(&pool->isolated_pages) == 0
Since we observe the pool->destroying (false) before atomic_long_dec()
for pool->isolated_pages, waking pool->migration_wait up is missed.
Fix this by ensure checking pool->destroying happens after the
atomic_long_dec(&pool->isolated_pages).
Link: https://lkml.kernel.org/r/20210708115027.7557-1-linmiaohe@huawei.com
Fixes: 701d678599 ("mm/zsmalloc.c: fix race condition in zs_destroy_pool")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Henry Burns <henryburns@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During migration special page table entries are installed for each page
being migrated. These entries store the pfn and associated permissions
of ptes mapping the page being migarted.
Device-private pages use special swap pte entries to distinguish
read-only vs. writeable pages which the migration code checks when
creating migration entries. Normally this follows a fast path in
migrate_vma_collect_pmd() which correctly copies the permissions of
device-private pages over to migration entries when migrating pages back
to the CPU.
However the slow-path falls back to using try_to_migrate() which
unconditionally creates read-only migration entries for device-private
pages. This leads to unnecessary double faults on the CPU as the new
pages are always mapped read-only even when they could be mapped
writeable. Fix this by correctly copying device-private permissions in
try_to_migrate_one().
Link: https://lkml.kernel.org/r/20211018045247.3128058-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reported-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Let's add a flag that corresponds to IORESOURCE_SYSRAM_DRIVER_MANAGED,
indicating that we're dealing with a memory region that is never
indicated in the firmware-provided memory map, but always detected and
added by a driver.
Similar to MEMBLOCK_HOTPLUG, most infrastructure has to treat such
memory regions like ordinary MEMBLOCK_NONE memory regions -- for
example, when selecting memory regions to add to the vmcore for dumping
in the crashkernel via for_each_mem_range().
However, especially kexec_file is not supposed to select such memblocks
via for_each_free_mem_range() / for_each_free_mem_range_reverse() to
place kexec images, similar to how we handle
IORESOURCE_SYSRAM_DRIVER_MANAGED without CONFIG_ARCH_KEEP_MEMBLOCK.
We'll make sure that memory hotplug code sets the flag where applicable
(IORESOURCE_SYSRAM_DRIVER_MANAGED) next. This prepares architectures
that need CONFIG_ARCH_KEEP_MEMBLOCK, such as arm64, for virtio-mem
support.
Note that kexec *must not* indicate this memory to the second kernel and
*must not* place kexec-images on this memory. Let's add a comment to
kexec_walk_memblock(), documenting how we handle MEMBLOCK_DRIVER_MANAGED
now just like using IORESOURCE_SYSRAM_DRIVER_MANAGED in
locate_mem_hole_callback() for kexec_walk_resources().
Also note that MEMBLOCK_HOTPLUG cannot be reused due to different
semantics:
MEMBLOCK_HOTPLUG: memory is indicated as "System RAM" in the
firmware-provided memory map and added to the system early during
boot; kexec *has to* indicate this memory to the second kernel and
can place kexec-images on this memory. After memory hotunplug,
kexec has to be re-armed. We mostly ignore this flag when
"movable_node" is not set on the kernel command line, because
then we're told to not care about hotunpluggability of such
memory regions.
MEMBLOCK_DRIVER_MANAGED: memory is not indicated as "System RAM" in
the firmware-provided memory map; this memory is always detected
and added to the system by a driver; memory might not actually be
physically hotunpluggable. kexec *must not* indicate this memory to
the second kernel and *must not* place kexec-images on this memory.
Link: https://lkml.kernel.org/r/20211004093605.5830-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jianyong Wu <Jianyong.Wu@arm.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Shahab Vahedi <shahab@synopsys.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We want to specify flags when hotplugging memory. Let's prepare to pass
flags to memblock_add_node() by adjusting all existing users.
Note that when hotplugging memory the system is already up and running
and we might have concurrent memblock users: for example, while we're
hotplugging memory, kexec_file code might search for suitable memory
regions to place kexec images. It's important to add the memory
directly to memblock via a single call with the right flags, instead of
adding the memory first and apply flags later: otherwise, concurrent
memblock users might temporarily stumble over memblocks with wrong
flags, which will be important in a follow-up patch that introduces a
new flag to properly handle add_memory_driver_managed().
Link: https://lkml.kernel.org/r/20211004093605.5830-4-david@redhat.com
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Shahab Vahedi <shahab@synopsys.com> [arch/arc]
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jianyong Wu <Jianyong.Wu@arm.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/memory_hotplug: full support for add_memory_driver_managed() with CONFIG_ARCH_KEEP_MEMBLOCK", v2.
Architectures that require CONFIG_ARCH_KEEP_MEMBLOCK=y, such as arm64,
don't cleanly support add_memory_driver_managed() yet. Most
prominently, kexec_file can still end up placing kexec images on such
driver-managed memory, resulting in undesired behavior, for example,
having kexec images located on memory not part of the firmware-provided
memory map.
Teaching kexec to not place images on driver-managed memory is
especially relevant for virtio-mem. Details can be found in commit
7b7b27214b ("mm/memory_hotplug: introduce
add_memory_driver_managed()").
Extend memblock with a new flag and set it from memory hotplug code when
applicable. This is required to fully support virtio-mem on arm64,
making also kexec_file behave like on x86-64.
This patch (of 2):
If memblock_add_node() fails, we're most probably running out of memory.
While this is unlikely to happen, it can happen and having memory added
without a memblock can be problematic for architectures that use
memblock to detect valid memory. Let's fail in a nice way instead of
silently ignoring the error.
Link: https://lkml.kernel.org/r/20211004093605.5830-1-david@redhat.com
Link: https://lkml.kernel.org/r/20211004093605.5830-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jianyong Wu <Jianyong.Wu@arm.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Shahab Vahedi <shahab@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't support CONFIG_MEMORY_HOTPLUG on 32 bit and consequently not
HIGHMEM. Let's remove any leftover code -- including the unused
"status_change_nid_high" field part of the memory notifier.
Link: https://lkml.kernel.org/r/20210929143600.49379-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
32 bit support is broken in various ways: for example, we can online
memory that should actually go to ZONE_HIGHMEM to ZONE_MOVABLE or in
some cases even to one of the other kernel zones.
We marked it BROKEN in commit b59d02ed08 ("mm/memory_hotplug: disable
the functionality for 32b") almost one year ago. According to that
commit it might be broken at least since 2017. Further, there is hardly
a sane use case nowadays.
Let's just depend completely on 64bit, dropping the "BROKEN" dependency
to make clear that we are not going to support it again. Next, we'll
remove some HIGHMEM leftovers from memory hotplug code to clean up.
Link: https://lkml.kernel.org/r/20210929143600.49379-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_MEMORY_HOTPLUG depends on CONFIG_SPARSEMEM, so there is no need for
CONFIG_MEMORY_HOTPLUG_SPARSE anymore; adjust all instances to use
CONFIG_MEMORY_HOTPLUG and remove CONFIG_MEMORY_HOTPLUG_SPARSE.
Link: https://lkml.kernel.org/r/20210929143600.49379-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org> [kselftest]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/memory_hotplug: Kconfig and 32 bit cleanups".
Some cleanups around CONFIG_MEMORY_HOTPLUG, including removing 32 bit
leftovers of memory hotplug support.
This patch (of 6):
SPARSEMEM is the only possible memory model for x86-64, FLATMEM is not
possible:
config ARCH_FLATMEM_ENABLE
def_bool y
depends on X86_32 && !NUMA
And X86_64_ACPI_NUMA (obviously) only supports x86-64:
config X86_64_ACPI_NUMA
def_bool y
depends on X86_64 && NUMA && ACPI && PCI
Let's just remove the CONFIG_X86_64_ACPI_NUMA dependency, as it does no
longer make sense.
Link: https://lkml.kernel.org/r/20210929143600.49379-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alex Shi <alexs@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
online_policy_to_str is only used in memory_hotplug.c and should be
defined as static.
Link: https://lkml.kernel.org/r/20210913024534.26161-1-tangyizhou@huawei.com
Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KCSAN reports a data-race on v5.10 which also exists on mainline:
BUG: KCSAN: data-race in extfrag_for_order+0x33/0x2d0
race at unknown origin, with read to 0xffff9ee9bfffab48 of 8 bytes by task 34 on cpu 1:
extfrag_for_order+0x33/0x2d0
kcompactd+0x5f0/0xce0
kthread+0x1f9/0x220
ret_from_fork+0x22/0x30
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 34 Comm: kcompactd0 Not tainted 5.10.0+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Access to zone->free_area[order].nr_free in extfrag_for_order() and
frag_show_print() is lockless. That's intentional and the stats are a
rough estimate anyway. Annotate them with data_race().
[liushixin2@huawei.com: add comments]
Link: https://lkml.kernel.org/r/20210918084655.2696522-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20210908015606.3999871-1-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When nommu, the arch_get_unmapped_area() will not be called, just kill
it.
Link: https://lkml.kernel.org/r/20210910061906.36299-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In fact, formated values returned by get_init_ra_size are not that
intuitive. This patch make the comments reflect its truth.
Link: https://lkml.kernel.org/r/20211019104812.135602-1-linf@wangsu.com
Signed-off-by: Lin Feng <linf@wangsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memory demotion needs to call migrate_pages() to do the jobs. And
it is controlled by a knob, however, the knob doesn't depend on
CONFIG_MIGRATION. The knob could be truned on even though MIGRATION is
disabled, this will not cause any crash since migrate_pages() would just
return -ENOSYS. But it is definitely not optimal to go through demotion
path then retry regular swap every time.
And it doesn't make too much sense to have the knob visible to the users
when !MIGRATION. Move the related code from mempolicy.[h|c] to
migrate.[h|c].
Link: https://lkml.kernel.org/r/20211015005559.246709-1-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In order to remove the need to manually keep three different files in
synch, provide a common definition of the mapping between enum
migrate_reason, and the associated strings for each enum item.
1. Use the tracing system's mapping of enums to strings, by redefining
and reusing the MIGRATE_REASON and supporting macros, and using that
to populate the string array in mm/debug.c.
2. Move enum migrate_reason to migrate_mode.h. This is not strictly
necessary for this patch, but migrate mode and migrate reason go
together, so this will slightly clarify things.
Link: https://lkml.kernel.org/r/20210922041755.141817-2-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Weizhao Ouyang <o451686892@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can specify the number of hugepages to allocate at boot. But the
hugepages is balanced in all nodes at present. In some scenarios, we
only need hugepages in one node. For example: DPDK needs hugepages
which are in the same node as NIC.
If DPDK needs four hugepages of 1G size in node1 and system has 16 numa
nodes we must reserve 64 hugepages on the kernel cmdline. But only four
hugepages are used. The others should be free after boot. If the
system memory is low(for example: 64G), it will be an impossible task.
So extend the hugepages parameter to support specifying hugepages on a
specific node. For example add following parameter:
hugepagesz=1G hugepages=0:1,1:3
It will allocate 1 hugepage in node0 and 3 hugepages in node1.
Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com
Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zhenguo Yao <yaozhenguo1@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The OOM reaper alters user address space which might theoretically alter
the snapshot if reaping is allowed to happen after the freezer quiescent
state. To this end, the reaper kthread uses wait_event_freezable()
while waiting for any work so that it cannot run while the system
freezes.
However, the current implementation doesn't respect the freezer because
all kernel threads are created with the PF_NOFREEZE flag, so they are
automatically excluded from freezing operations. This means that the
OOM reaper can race with system snapshotting if it has work to do while
the system is being frozen.
Fix this by adding a set_freezable() call which will clear the
PF_NOFREEZE flag and thus make the OOM reaper visible to the freezer.
Please note that the OOM reaper altering the snapshot this way is mostly
a theoretical concern and has not been observed in practice.
Link: https://lkml.kernel.org/r/20210921165758.6154-1-sultan@kerneltoast.com
Link: https://lkml.kernel.org/r/20210918233920.9174-1-sultan@kerneltoast.com
Fixes: aac4536355 ("mm, oom: introduce oom reaper")
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename memblock_free_ptr() to memblock_free() and use memblock_free()
when freeing a virtual pointer so that memblock_free() will be a
counterpart of memblock_alloc()
The callers are updated with the below semantic patch and manual
addition of (void *) casting to pointers that are represented by
unsigned long variables.
@@
identifier vaddr;
expression size;
@@
(
- memblock_phys_free(__pa(vaddr), size);
+ memblock_free(vaddr, size);
|
- memblock_free_ptr(vaddr, size);
+ memblock_free(vaddr, size);
)
[sfr@canb.auug.org.au: fixup]
Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au
Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Juergen Gross <jgross@suse.com>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since memblock_free() operates on a physical range, make its name
reflect it and rename it to memblock_phys_free(), so it will be a
logical counterpart to memblock_phys_alloc().
The callers are updated with the below semantic patch:
@@
expression addr;
expression size;
@@
- memblock_free(addr, size);
+ memblock_phys_free(addr, size);
Link: https://lkml.kernel.org/r/20210930185031.18648-6-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Juergen Gross <jgross@suse.com>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memblock_free_late() is a NOP wrapper for __memblock_free_late(), there
is no point to keep this indirection.
Drop the wrapper and rename __memblock_free_late() to
memblock_free_late().
Link: https://lkml.kernel.org/r/20210930185031.18648-5-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Juergen Gross <jgross@suse.com>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memblock_free_early_nid() is unused and memblock_free_early() is an
alias for memblock_free().
Replace calls to memblock_free_early() with calls to memblock_free() and
remove memblock_free_early() and memblock_free_early_nid().
Link: https://lkml.kernel.org/r/20210930185031.18648-4-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Juergen Gross <jgross@suse.com>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When reading memcg->socket_pressure in mem_cgroup_under_socket_pressure()
and writing memcg->socket_pressure in vmpressure() at the same time, the
following data-race occurs:
BUG: KCSAN: data-race in __sk_mem_reduce_allocated / vmpressure
write to 0xffff8881286f4938 of 8 bytes by task 24550 on cpu 3:
vmpressure+0x218/0x230 mm/vmpressure.c:307
shrink_node_memcgs+0x2b9/0x410 mm/vmscan.c:2658
shrink_node+0x9d2/0x11d0 mm/vmscan.c:2769
shrink_zones+0x29f/0x470 mm/vmscan.c:2972
do_try_to_free_pages+0x193/0x6e0 mm/vmscan.c:3027
try_to_free_mem_cgroup_pages+0x1c0/0x3f0 mm/vmscan.c:3345
reclaim_high mm/memcontrol.c:2440 [inline]
mem_cgroup_handle_over_high+0x18b/0x4d0 mm/memcontrol.c:2624
tracehook_notify_resume include/linux/tracehook.h:197 [inline]
exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
exit_to_user_mode_prepare+0x110/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:289
read to 0xffff8881286f4938 of 8 bytes by interrupt on cpu 1:
mem_cgroup_under_socket_pressure include/linux/memcontrol.h:1483 [inline]
sk_under_memory_pressure include/net/sock.h:1314 [inline]
__sk_mem_reduce_allocated+0x1d2/0x270 net/core/sock.c:2696
__sk_mem_reclaim+0x44/0x50 net/core/sock.c:2711
sk_mem_reclaim include/net/sock.h:1490 [inline]
......
net_rx_action+0x17a/0x480 net/core/dev.c:6864
__do_softirq+0x12c/0x2af kernel/softirq.c:298
run_ksoftirqd+0x13/0x20 kernel/softirq.c:653
smpboot_thread_fn+0x33f/0x510 kernel/smpboot.c:165
kthread+0x1fc/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Fix it by using READ_ONCE() and WRITE_ONCE() to read and write
memcg->socket_pressure.
Link: https://lkml.kernel.org/r/20211025082843.671690-1-songyuanzheng@huawei.com
Signed-off-by: Yuanzheng Song <songyuanzheng@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tracing indicates that tasks throttled on NOPROGRESS are woken
prematurely resulting in occasional massive spikes in direct reclaim
activity. This patch wakes tasks throttled on NOPROGRESS if reclaim
efficiency is at least 12%.
Link: https://lkml.kernel.org/r/20211022144651.19914-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tracing of the stutterp workload showed the following delays
1 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=536000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=544000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=556000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=624000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=716000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=772000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usect_delayed=512000 reason=VMSCAN_THROTTLE_NOPROGRESS
16 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
53 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
116 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
5907 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
71741 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS
All the throttling hit the full timeout and then there was wakeup delays
meaning that the wakeups are premature as no other reclaimer such as
kswapd has made progress. This patch increases the maximum timeout.
Link: https://lkml.kernel.org/r/20211022144651.19914-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Neil Brown raised concerns about callers of reclaim_throttle specifying
a timeout value. The original timeout values to congestion_wait() were
probably pulled out of thin air or copy&pasted from somewhere else.
This patch centralises the timeout values and selects a timeout based on
the reason for reclaim throttling. These figures are also pulled out of
the same thin air but better values may be derived
Running a workload that is throttling for inappropriate periods and
tracing mm_vmscan_throttled can be used to pick a more appropriate
value. Excessive throttling would pick a lower timeout where as
excessive CPU usage in reclaim context would select a larger timeout.
Ideally a large value would always be used and the wakeups would occur
before a timeout but that requires careful testing.
Link: https://lkml.kernel.org/r/20211022144651.19914-7-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page allocator stalls based on the number of pages that are waiting
for writeback to start but this should now be redundant.
shrink_inactive_list() will wake flusher threads if the LRU tail are
unqueued dirty pages so the flusher should be active. If it fails to
make progress due to pages under writeback not being completed quickly
then it should stall on VMSCAN_THROTTLE_WRITEBACK.
Link: https://lkml.kernel.org/r/20211022144651.19914-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_writepages throttles on congestion if the writepages() fails due to a
lack of memory but congestion_wait() is partially broken as the
congestion state is not updated for all BDIs.
This patch stalls waiting for a number of pages to complete writeback
that located on the local node. The main weakness is that there is no
correlation between the location of the inode's pages and locality but
that is still better than congestion_wait.
Link: https://lkml.kernel.org/r/20211022144651.19914-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memcg reclaim throttles on congestion if no reclaim progress is made.
This makes little sense, it might be due to writeback or a host of other
factors.
For !memcg reclaim, it's messy. Direct reclaim primarily is throttled
in the page allocator if it is failing to make progress. Kswapd
throttles if too many pages are under writeback and marked for immediate
reclaim.
This patch explicitly throttles if reclaim is failing to make progress.
[vbabka@suse.cz: Remove redundant code]
Link: https://lkml.kernel.org/r/20211022144651.19914-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page reclaim throttles on congestion if too many parallel reclaim
instances have isolated too many pages. This makes no sense, excessive
parallelisation has nothing to do with writeback or congestion.
This patch creates an additional workqueue to sleep on when too many
pages are isolated. The throttled tasks are woken when the number of
isolated pages is reduced or a timeout occurs. There may be some false
positive wakeups for GFP_NOIO/GFP_NOFS callers but the tasks will
throttle again if necessary.
[shy828301@gmail.com: Wake up from compaction context]
[vbabka@suse.cz: Account number of throttled tasks only for writeback]
Link: https://lkml.kernel.org/r/20211022144651.19914-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Remove dependency on congestion_wait in mm/", v5.
This series that removes all calls to congestion_wait in mm/ and deletes
wait_iff_congested. It's not a clever implementation but
congestion_wait has been broken for a long time [1].
Even if congestion throttling worked, it was never a great idea. While
excessive dirty/writeback pages at the tail of the LRU is one
possibility that reclaim may be slow, there is also the problem of too
many pages being isolated and reclaim failing for other reasons
(elevated references, too many pages isolated, excessive LRU contention
etc).
This series replaces the "congestion" throttling with 3 different types.
- If there are too many dirty/writeback pages, sleep until a timeout or
enough pages get cleaned
- If too many pages are isolated, sleep until enough isolated pages are
either reclaimed or put back on the LRU
- If no progress is being made, direct reclaim tasks sleep until
another task makes progress with acceptable efficiency.
This was initially tested with a mix of workloads that used to trigger
corner cases that no longer work. A new test case was created called
"stutterp" (pagereclaim-stutterp-noreaders in mmtests) using a freshly
created XFS filesystem. Note that it may be necessary to increase the
timeout of ssh if executing remotely as ssh itself can get throttled and
the connection may timeout.
stutterp varies the number of "worker" processes from 4 up to NR_CPUS*4
to check the impact as the number of direct reclaimers increase. It has
four types of worker.
- One "anon latency" worker creates small mappings with mmap() and
times how long it takes to fault the mapping reading it 4K at a time
- X file writers which is fio randomly writing X files where the total
size of the files add up to the allowed dirty_ratio. fio is allowed
to run for a warmup period to allow some file-backed pages to
accumulate. The duration of the warmup is based on the best-case
linear write speed of the storage.
- Y file readers which is fio randomly reading small files
- Z anon memory hogs which continually map (100-dirty_ratio)% of memory
- Total estimated WSS = (100+dirty_ration) percentage of memory
X+Y+Z+1 == NR_WORKERS varying from 4 up to NR_CPUS*4
The intent is to maximise the total WSS with a mix of file and anon
memory where some anonymous memory must be swapped and there is a high
likelihood of dirty/writeback pages reaching the end of the LRU.
The test can be configured to have no background readers to stress
dirty/writeback pages. The results below are based on having zero
readers.
The short summary of the results is that the series works and stalls
until some event occurs but the timeouts may need adjustment.
The test results are not broken down by patch as the series should be
treated as one block that replaces a broken throttling mechanism with a
working one.
Finally, three machines were tested but I'm reporting the worst set of
results. The other two machines had much better latencies for example.
First the results of the "anon latency" latency
stutterp
5.15.0-rc1 5.15.0-rc1
vanilla mm-reclaimcongest-v5r4
Amean mmap-4 31.4003 ( 0.00%) 2661.0198 (-8374.52%)
Amean mmap-7 38.1641 ( 0.00%) 149.2891 (-291.18%)
Amean mmap-12 60.0981 ( 0.00%) 187.8105 (-212.51%)
Amean mmap-21 161.2699 ( 0.00%) 213.9107 ( -32.64%)
Amean mmap-30 174.5589 ( 0.00%) 377.7548 (-116.41%)
Amean mmap-48 8106.8160 ( 0.00%) 1070.5616 ( 86.79%)
Stddev mmap-4 41.3455 ( 0.00%) 27573.9676 (-66591.66%)
Stddev mmap-7 53.5556 ( 0.00%) 4608.5860 (-8505.23%)
Stddev mmap-12 171.3897 ( 0.00%) 5559.4542 (-3143.75%)
Stddev mmap-21 1506.6752 ( 0.00%) 5746.2507 (-281.39%)
Stddev mmap-30 557.5806 ( 0.00%) 7678.1624 (-1277.05%)
Stddev mmap-48 61681.5718 ( 0.00%) 14507.2830 ( 76.48%)
Max-90 mmap-4 31.4243 ( 0.00%) 83.1457 (-164.59%)
Max-90 mmap-7 41.0410 ( 0.00%) 41.0720 ( -0.08%)
Max-90 mmap-12 66.5255 ( 0.00%) 53.9073 ( 18.97%)
Max-90 mmap-21 146.7479 ( 0.00%) 105.9540 ( 27.80%)
Max-90 mmap-30 193.9513 ( 0.00%) 64.3067 ( 66.84%)
Max-90 mmap-48 277.9137 ( 0.00%) 591.0594 (-112.68%)
Max mmap-4 1913.8009 ( 0.00%) 299623.9695 (-15555.96%)
Max mmap-7 2423.9665 ( 0.00%) 204453.1708 (-8334.65%)
Max mmap-12 6845.6573 ( 0.00%) 221090.3366 (-3129.64%)
Max mmap-21 56278.6508 ( 0.00%) 213877.3496 (-280.03%)
Max mmap-30 19716.2990 ( 0.00%) 216287.6229 (-997.00%)
Max mmap-48 477923.9400 ( 0.00%) 245414.8238 ( 48.65%)
For most thread counts, the time to mmap() is unfortunately increased.
In earlier versions of the series, this was lower but a large number of
throttling events were reaching their timeout increasing the amount of
inefficient scanning of the LRU. There is no prioritisation of reclaim
tasks making progress based on each tasks rate of page allocation versus
progress of reclaim. The variance is also impacted for high worker
counts but in all cases, the differences in latency are not
statistically significant due to very large maximum outliers. Max-90
shows that 90% of the stalls are comparable but the Max results show the
massive outliers which are increased to to stalling.
It is expected that this will be very machine dependant. Due to the
test design, reclaim is difficult so allocations stall and there are
variances depending on whether THPs can be allocated or not. The amount
of memory will affect exactly how bad the corner cases are and how often
they trigger. The warmup period calculation is not ideal as it's based
on linear writes where as fio is randomly writing multiple files from
multiple tasks so the start state of the test is variable. For example,
these are the latencies on a single-socket machine that had more memory
Amean mmap-4 42.2287 ( 0.00%) 49.6838 * -17.65%*
Amean mmap-7 216.4326 ( 0.00%) 47.4451 * 78.08%*
Amean mmap-12 2412.0588 ( 0.00%) 51.7497 ( 97.85%)
Amean mmap-21 5546.2548 ( 0.00%) 51.8862 ( 99.06%)
Amean mmap-30 1085.3121 ( 0.00%) 72.1004 ( 93.36%)
The overall system CPU usage and elapsed time is as follows
5.15.0-rc3 5.15.0-rc3
vanilla mm-reclaimcongest-v5r4
Duration User 6989.03 983.42
Duration System 7308.12 799.68
Duration Elapsed 2277.67 2092.98
The patches reduce system CPU usage by 89% as the vanilla kernel is rarely
stalling.
The high-level /proc/vmstats show
5.15.0-rc1 5.15.0-rc1
vanilla mm-reclaimcongest-v5r2
Ops Direct pages scanned 1056608451.00 503594991.00
Ops Kswapd pages scanned 109795048.00 147289810.00
Ops Kswapd pages reclaimed 63269243.00 31036005.00
Ops Direct pages reclaimed 10803973.00 6328887.00
Ops Kswapd efficiency % 57.62 21.07
Ops Kswapd velocity 48204.98 57572.86
Ops Direct efficiency % 1.02 1.26
Ops Direct velocity 463898.83 196845.97
Kswapd scanned less pages but the detailed pattern is different. The
vanilla kernel scans slowly over time where as the patches exhibits
burst patterns of scan activity. Direct reclaim scanning is reduced by
52% due to stalling.
The pattern for stealing pages is also slightly different. Both kernels
exhibit spikes but the vanilla kernel when reclaiming shows pages being
reclaimed over a period of time where as the patches tend to reclaim in
spikes. The difference is that vanilla is not throttling and instead
scanning constantly finding some pages over time where as the patched
kernel throttles and reclaims in spikes.
Ops Percentage direct scans 90.59 77.37
For direct reclaim, vanilla scanned 90.59% of pages where as with the
patches, 77.37% were direct reclaim due to throttling
Ops Page writes by reclaim 2613590.00 1687131.00
Page writes from reclaim context are reduced.
Ops Page writes anon 2932752.00 1917048.00
And there is less swapping.
Ops Page reclaim immediate 996248528.00 107664764.00
The number of pages encountered at the tail of the LRU tagged for
immediate reclaim but still dirty/writeback is reduced by 89%.
Ops Slabs scanned 164284.00 153608.00
Slab scan activity is similar.
ftrace was used to gather stall activity
Vanilla
-------
1 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=16000
2 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=12000
8 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=8000
29 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=4000
82394 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=0
The fast majority of wait_iff_congested calls do not stall at all. What
is likely happening is that cond_resched() reschedules the task for a
short period when the BDI is not registering congestion (which it never
will in this test setup).
1 writeback_congestion_wait: usec_timeout=100000 usec_delayed=120000
2 writeback_congestion_wait: usec_timeout=100000 usec_delayed=132000
4 writeback_congestion_wait: usec_timeout=100000 usec_delayed=112000
380 writeback_congestion_wait: usec_timeout=100000 usec_delayed=108000
778 writeback_congestion_wait: usec_timeout=100000 usec_delayed=104000
congestion_wait if called always exceeds the timeout as there is no
trigger to wake it up.
Bottom line: Vanilla will throttle but it's not effective.
Patch series
------------
Kswapd throttle activity was always due to scanning pages tagged for
immediate reclaim at the tail of the LRU
1 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK
4 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK
6 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK
94 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK
112 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority of events did not stall or stalled for a short period.
Roughly 16% of stalls reached the timeout before expiry. For direct
reclaim, the number of times stalled for each reason were
6624 reason=VMSCAN_THROTTLE_ISOLATED
93246 reason=VMSCAN_THROTTLE_NOPROGRESS
96934 reason=VMSCAN_THROTTLE_WRITEBACK
The most common reason to stall was due to excessive pages tagged for
immediate reclaim at the tail of the LRU followed by a failure to make
forward. A relatively small number were due to too many pages isolated
from the LRU by parallel threads
For VMSCAN_THROTTLE_ISOLATED, the breakdown of delays was
9 usec_timeout=20000 usect_delayed=4000 reason=VMSCAN_THROTTLE_ISOLATED
12 usec_timeout=20000 usect_delayed=16000 reason=VMSCAN_THROTTLE_ISOLATED
83 usec_timeout=20000 usect_delayed=20000 reason=VMSCAN_THROTTLE_ISOLATED
6520 usec_timeout=20000 usect_delayed=0 reason=VMSCAN_THROTTLE_ISOLATED
Most did not stall at all. A small number reached the timeout.
For VMSCAN_THROTTLE_NOPROGRESS, the breakdown of stalls were all over
the map
1 usec_timeout=500000 usect_delayed=324000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=332000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=348000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usec_timeout=500000 usect_delayed=360000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=228000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=260000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=340000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=364000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=372000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=428000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=460000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usec_timeout=500000 usect_delayed=464000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=244000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=252000 reason=VMSCAN_THROTTLE_NOPROGRESS
3 usec_timeout=500000 usect_delayed=272000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=188000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=268000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=328000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=380000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=392000 reason=VMSCAN_THROTTLE_NOPROGRESS
4 usec_timeout=500000 usect_delayed=432000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=204000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=220000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=412000 reason=VMSCAN_THROTTLE_NOPROGRESS
5 usec_timeout=500000 usect_delayed=436000 reason=VMSCAN_THROTTLE_NOPROGRESS
6 usec_timeout=500000 usect_delayed=488000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=212000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=300000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=316000 reason=VMSCAN_THROTTLE_NOPROGRESS
7 usec_timeout=500000 usect_delayed=472000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=248000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=356000 reason=VMSCAN_THROTTLE_NOPROGRESS
8 usec_timeout=500000 usect_delayed=456000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=376000 reason=VMSCAN_THROTTLE_NOPROGRESS
9 usec_timeout=500000 usect_delayed=484000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=172000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=420000 reason=VMSCAN_THROTTLE_NOPROGRESS
10 usec_timeout=500000 usect_delayed=452000 reason=VMSCAN_THROTTLE_NOPROGRESS
11 usec_timeout=500000 usect_delayed=256000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=144000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=152000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=264000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=384000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=424000 reason=VMSCAN_THROTTLE_NOPROGRESS
12 usec_timeout=500000 usect_delayed=492000 reason=VMSCAN_THROTTLE_NOPROGRESS
13 usec_timeout=500000 usect_delayed=184000 reason=VMSCAN_THROTTLE_NOPROGRESS
13 usec_timeout=500000 usect_delayed=444000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=308000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=440000 reason=VMSCAN_THROTTLE_NOPROGRESS
14 usec_timeout=500000 usect_delayed=476000 reason=VMSCAN_THROTTLE_NOPROGRESS
16 usec_timeout=500000 usect_delayed=140000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=232000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=240000 reason=VMSCAN_THROTTLE_NOPROGRESS
17 usec_timeout=500000 usect_delayed=280000 reason=VMSCAN_THROTTLE_NOPROGRESS
18 usec_timeout=500000 usect_delayed=404000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=148000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=216000 reason=VMSCAN_THROTTLE_NOPROGRESS
20 usec_timeout=500000 usect_delayed=468000 reason=VMSCAN_THROTTLE_NOPROGRESS
21 usec_timeout=500000 usect_delayed=448000 reason=VMSCAN_THROTTLE_NOPROGRESS
23 usec_timeout=500000 usect_delayed=168000 reason=VMSCAN_THROTTLE_NOPROGRESS
23 usec_timeout=500000 usect_delayed=296000 reason=VMSCAN_THROTTLE_NOPROGRESS
25 usec_timeout=500000 usect_delayed=132000 reason=VMSCAN_THROTTLE_NOPROGRESS
25 usec_timeout=500000 usect_delayed=352000 reason=VMSCAN_THROTTLE_NOPROGRESS
26 usec_timeout=500000 usect_delayed=180000 reason=VMSCAN_THROTTLE_NOPROGRESS
27 usec_timeout=500000 usect_delayed=284000 reason=VMSCAN_THROTTLE_NOPROGRESS
28 usec_timeout=500000 usect_delayed=164000 reason=VMSCAN_THROTTLE_NOPROGRESS
29 usec_timeout=500000 usect_delayed=136000 reason=VMSCAN_THROTTLE_NOPROGRESS
30 usec_timeout=500000 usect_delayed=200000 reason=VMSCAN_THROTTLE_NOPROGRESS
30 usec_timeout=500000 usect_delayed=400000 reason=VMSCAN_THROTTLE_NOPROGRESS
31 usec_timeout=500000 usect_delayed=196000 reason=VMSCAN_THROTTLE_NOPROGRESS
32 usec_timeout=500000 usect_delayed=156000 reason=VMSCAN_THROTTLE_NOPROGRESS
33 usec_timeout=500000 usect_delayed=224000 reason=VMSCAN_THROTTLE_NOPROGRESS
35 usec_timeout=500000 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
35 usec_timeout=500000 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
36 usec_timeout=500000 usect_delayed=368000 reason=VMSCAN_THROTTLE_NOPROGRESS
36 usec_timeout=500000 usect_delayed=496000 reason=VMSCAN_THROTTLE_NOPROGRESS
37 usec_timeout=500000 usect_delayed=312000 reason=VMSCAN_THROTTLE_NOPROGRESS
38 usec_timeout=500000 usect_delayed=304000 reason=VMSCAN_THROTTLE_NOPROGRESS
40 usec_timeout=500000 usect_delayed=288000 reason=VMSCAN_THROTTLE_NOPROGRESS
43 usec_timeout=500000 usect_delayed=408000 reason=VMSCAN_THROTTLE_NOPROGRESS
55 usec_timeout=500000 usect_delayed=416000 reason=VMSCAN_THROTTLE_NOPROGRESS
56 usec_timeout=500000 usect_delayed=76000 reason=VMSCAN_THROTTLE_NOPROGRESS
58 usec_timeout=500000 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
59 usec_timeout=500000 usect_delayed=208000 reason=VMSCAN_THROTTLE_NOPROGRESS
61 usec_timeout=500000 usect_delayed=68000 reason=VMSCAN_THROTTLE_NOPROGRESS
71 usec_timeout=500000 usect_delayed=192000 reason=VMSCAN_THROTTLE_NOPROGRESS
71 usec_timeout=500000 usect_delayed=480000 reason=VMSCAN_THROTTLE_NOPROGRESS
79 usec_timeout=500000 usect_delayed=60000 reason=VMSCAN_THROTTLE_NOPROGRESS
82 usec_timeout=500000 usect_delayed=320000 reason=VMSCAN_THROTTLE_NOPROGRESS
82 usec_timeout=500000 usect_delayed=92000 reason=VMSCAN_THROTTLE_NOPROGRESS
85 usec_timeout=500000 usect_delayed=64000 reason=VMSCAN_THROTTLE_NOPROGRESS
85 usec_timeout=500000 usect_delayed=80000 reason=VMSCAN_THROTTLE_NOPROGRESS
88 usec_timeout=500000 usect_delayed=84000 reason=VMSCAN_THROTTLE_NOPROGRESS
90 usec_timeout=500000 usect_delayed=160000 reason=VMSCAN_THROTTLE_NOPROGRESS
90 usec_timeout=500000 usect_delayed=292000 reason=VMSCAN_THROTTLE_NOPROGRESS
94 usec_timeout=500000 usect_delayed=56000 reason=VMSCAN_THROTTLE_NOPROGRESS
118 usec_timeout=500000 usect_delayed=88000 reason=VMSCAN_THROTTLE_NOPROGRESS
119 usec_timeout=500000 usect_delayed=72000 reason=VMSCAN_THROTTLE_NOPROGRESS
126 usec_timeout=500000 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
146 usec_timeout=500000 usect_delayed=52000 reason=VMSCAN_THROTTLE_NOPROGRESS
148 usec_timeout=500000 usect_delayed=36000 reason=VMSCAN_THROTTLE_NOPROGRESS
148 usec_timeout=500000 usect_delayed=48000 reason=VMSCAN_THROTTLE_NOPROGRESS
159 usec_timeout=500000 usect_delayed=28000 reason=VMSCAN_THROTTLE_NOPROGRESS
178 usec_timeout=500000 usect_delayed=44000 reason=VMSCAN_THROTTLE_NOPROGRESS
183 usec_timeout=500000 usect_delayed=40000 reason=VMSCAN_THROTTLE_NOPROGRESS
237 usec_timeout=500000 usect_delayed=100000 reason=VMSCAN_THROTTLE_NOPROGRESS
266 usec_timeout=500000 usect_delayed=32000 reason=VMSCAN_THROTTLE_NOPROGRESS
313 usec_timeout=500000 usect_delayed=24000 reason=VMSCAN_THROTTLE_NOPROGRESS
347 usec_timeout=500000 usect_delayed=96000 reason=VMSCAN_THROTTLE_NOPROGRESS
470 usec_timeout=500000 usect_delayed=20000 reason=VMSCAN_THROTTLE_NOPROGRESS
559 usec_timeout=500000 usect_delayed=16000 reason=VMSCAN_THROTTLE_NOPROGRESS
964 usec_timeout=500000 usect_delayed=12000 reason=VMSCAN_THROTTLE_NOPROGRESS
2001 usec_timeout=500000 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS
2447 usec_timeout=500000 usect_delayed=8000 reason=VMSCAN_THROTTLE_NOPROGRESS
7888 usec_timeout=500000 usect_delayed=4000 reason=VMSCAN_THROTTLE_NOPROGRESS
22727 usec_timeout=500000 usect_delayed=0 reason=VMSCAN_THROTTLE_NOPROGRESS
51305 usec_timeout=500000 usect_delayed=500000 reason=VMSCAN_THROTTLE_NOPROGRESS
The full timeout is often hit but a large number also do not stall at
all. The remainder slept a little allowing other reclaim tasks to make
progress.
While this timeout could be further increased, it could also negatively
impact worst-case behaviour when there is no prioritisation of what task
should make progress.
For VMSCAN_THROTTLE_WRITEBACK, the breakdown was
1 usec_timeout=100000 usect_delayed=44000 reason=VMSCAN_THROTTLE_WRITEBACK
2 usec_timeout=100000 usect_delayed=76000 reason=VMSCAN_THROTTLE_WRITEBACK
3 usec_timeout=100000 usect_delayed=80000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=48000 reason=VMSCAN_THROTTLE_WRITEBACK
5 usec_timeout=100000 usect_delayed=84000 reason=VMSCAN_THROTTLE_WRITEBACK
6 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK
7 usec_timeout=100000 usect_delayed=88000 reason=VMSCAN_THROTTLE_WRITEBACK
11 usec_timeout=100000 usect_delayed=56000 reason=VMSCAN_THROTTLE_WRITEBACK
12 usec_timeout=100000 usect_delayed=64000 reason=VMSCAN_THROTTLE_WRITEBACK
16 usec_timeout=100000 usect_delayed=92000 reason=VMSCAN_THROTTLE_WRITEBACK
24 usec_timeout=100000 usect_delayed=68000 reason=VMSCAN_THROTTLE_WRITEBACK
28 usec_timeout=100000 usect_delayed=32000 reason=VMSCAN_THROTTLE_WRITEBACK
30 usec_timeout=100000 usect_delayed=60000 reason=VMSCAN_THROTTLE_WRITEBACK
30 usec_timeout=100000 usect_delayed=96000 reason=VMSCAN_THROTTLE_WRITEBACK
32 usec_timeout=100000 usect_delayed=52000 reason=VMSCAN_THROTTLE_WRITEBACK
42 usec_timeout=100000 usect_delayed=40000 reason=VMSCAN_THROTTLE_WRITEBACK
77 usec_timeout=100000 usect_delayed=28000 reason=VMSCAN_THROTTLE_WRITEBACK
99 usec_timeout=100000 usect_delayed=36000 reason=VMSCAN_THROTTLE_WRITEBACK
137 usec_timeout=100000 usect_delayed=24000 reason=VMSCAN_THROTTLE_WRITEBACK
190 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK
339 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK
518 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK
852 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK
3359 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK
7147 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK
83962 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority hit the timeout in direct reclaim context although a
sizable number did not stall at all. This is very different to kswapd
where only a tiny percentage of stalls due to writeback reached the
timeout.
Bottom line, the throttling appears to work and the wakeup events may
limit worst case stalls. There might be some grounds for adjusting
timeouts but it's likely futile as the worst-case scenarios depend on
the workload, memory size and the speed of the storage. A better
approach to improve the series further would be to prioritise tasks
based on their rate of allocation with the caveat that it may be very
expensive to track.
This patch (of 5):
Page reclaim throttles on wait_iff_congested under the following
conditions:
- kswapd is encountering pages under writeback and marked for immediate
reclaim implying that pages are cycling through the LRU faster than
pages can be cleaned.
- Direct reclaim will stall if all dirty pages are backed by congested
inodes.
wait_iff_congested is almost completely broken with few exceptions.
This patch adds a new node-based workqueue and tracks the number of
throttled tasks and pages written back since throttling started. If
enough pages belonging to the node are written back then the throttled
tasks will wake early. If not, the throttled tasks sleeps until the
timeout expires.
[neilb@suse.de: Uninterruptible sleep and simpler wakeups]
[hdanton@sina.com: Avoid race when reclaim starts]
[vbabka@suse.cz: vmstat irq-safe api, clarifications]
Link: https://lore.kernel.org/linux-mm/45d8b7a6-8548-65f5-cccf-9f451d4ae3d4@kernel.dk/ [1]
Link: https://lkml.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20211022144651.19914-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: NeilBrown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We fix the following warning when building kernel with W=1:
mm/vmscan.c:1362:6: warning: variable 'err' set but not used [-Wunused-but-set-variable]
Link: https://lkml.kernel.org/r/20210924181218.21165-1-songkai01@inspur.com
Signed-off-by: Kai Song <songkai01@inspur.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Isolating a free page in an isolated pageblock is expected to always
work as watermarks don't apply here.
But if __isolate_free_page() failed, due to condition changes, the page
will be left on the free list. And the page will be put back to free
list again via __putback_isolated_page(). This may trigger
VM_BUG_ON_PAGE() on page->flags checking in __free_one_page() if
PageReported is set. Or we will corrupt the free list because
list_add() will be called for pages already on another list.
Add a VM_WARN_ON() to complain about this change.
Link: https://lkml.kernel.org/r/20210914114508.23725-1-linmiaohe@huawei.com
Fixes: 3c605096d3 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In start_isolate_page_range() undo path, pfn_to_online_page() just
checks the first pfn in a pageblock while __first_valid_page() will
traverse the pageblock until the first online pfn is found. So we may
miss the call to unset_migratetype_isolate() in undo path and pages will
remain isolated unexpectedly.
Fix this by calling undo_isolate_page_range() and this will also help to
simplify the code further. Note we shouldn't ever trigger it because
MAX_ORDER-1 aligned pfn ranges shouldn't contain memory holes now.
Link: https://lkml.kernel.org/r/20210914114348.15569-1-linmiaohe@huawei.com
Fixes: 2ce13640b3 ("mm: __first_valid_page skip over offline pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 7118fc2906 ("hugetlb: address ref count racing in
prep_compound_gigantic_page"), page_ref_freeze is used to atomically
zero the ref count of tail pages iff they are 1. The unconditional call
to set_page_count(0) was left in the code. This call is after
page_ref_freeze so it is really a noop.
Remove redundant and unnecessary set_page_count call.
Link: https://lkml.kernel.org/r/20211026220635.35187-1-mike.kravetz@oracle.com
Fixes: 7118fc2906 ("hugetlb: address ref count racing in prep_compound_gigantic_page")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When calling hugetlb_resv_map_add(), we've guaranteed that the parameter
'to' is always larger than 'from', so it never returns a negative value
from hugetlb_resv_map_add(). Thus remove the redundant VM_BUG_ON().
Link: https://lkml.kernel.org/r/2b565552f3d06753da1e8dda439c0d96d6d9a5a3.1634797639.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The callers of has_same_uncharge_info() has accessed the original
file_region and new file_region, and they are impossible to be NULL now.
So we can remove the file_region validation in has_same_uncharge_info()
to simplify the code.
Link: https://lkml.kernel.org/r/97fc68d3f8d34f63c204645e10d7a718997e50b7.1634797639.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After commit 8382d914eb ("mm, hugetlb: improve page-fault
scalability"), the hugetlb_instantiation_mutex lock had been replaced by
hugetlb_fault_mutex_table to serializes faults on the same logical page.
Thus update the obsolete hugetlb_instantiation_mutex related comments.
Link: https://lkml.kernel.org/r/4b3febeae37455ff7b74aa0aad16cc6909cf0926.1634797639.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now the size of CMA area for gigantic hugepages runtime allocation is
balanced for all online nodes, but we also want to specify the size of
CMA per-node, or only one node in some cases, which are similar with
patch [1].
For example, on some multi-nodes systems, each node's memory can be
different, allocating the same size of CMA for each node is not suitable
for the low-memory nodes. Meanwhile some workloads like DPDK mentioned
by Zhenguo in patch [1] only need hugepages in one node.
On the other hand, we have some machines with multiple types of memory,
like DRAM and PMEM (persistent memory). On this system, we may want to
specify all the hugepages only on DRAM node, or specify the proportion
of DRAM node and PMEM node, to tuning the performance of the workloads.
Thus this patch adds node format for 'hugetlb_cma' parameter to support
specifying the size of CMA per-node. An example is as follows:
hugetlb_cma=0:5G,2:5G
which means allocating 5G size of CMA area on node 0 and node 2
respectively. And the users should use the node specific sysfs file to
allocate the gigantic hugepages if specified the CMA size on that node.
Link: https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com [1]
Link: https://lkml.kernel.org/r/bb790775ca60bb8f4b26956bb3f6988f74e075c7.1634261144.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Support mremap() for hugepage backed vma segment by simply repositioning
page table entries. The page table entries are repositioned to the new
virtual address on mremap().
Hugetlb mremap() support is of course generic; my motivating use case is
a library (hugepage_text), which reloads the ELF text of executables in
hugepages. This significantly increases the execution performance of
said executables.
Restrict the mremap operation on hugepages to up to the size of the
original mapping as the underlying hugetlb reservation is not yet
capable of handling remapping to a larger size.
During the mremap() operation we detect pmd_share'd mappings and we
unshare those during the mremap(). On access and fault the sharing is
established again.
Link: https://lkml.kernel.org/r/20211013195825.3058275-1-almasrymina@google.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ken Chen <kenchen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When initializing transparent huge pages, min_free_kbytes would be
calculated according to what khugepaged expected.
So when transparent huge pages get disabled, min_free_kbytes should be
recalculated instead of the higher value set by khugepaged.
Link: https://lkml.kernel.org/r/1633937809-16558-1-git-send-email-liangcaifan19@gmail.com
Signed-off-by: Liangcai Fan <liangcaifan19@gmail.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Demote page functionality will split a huge page into a number of huge
pages of a smaller size. For example, on x86 a 1GB huge page can be
demoted into 512 2M huge pages. Demotion is done 'in place' by simply
splitting the huge page.
Added '*_for_demote' wrappers for remove_hugetlb_page,
destroy_compound_hugetlb_page and prep_compound_gigantic_page for use by
demote code.
[mike.kravetz@oracle.com: v4]
Link: https://lkml.kernel.org/r/6ca29b8e-527c-d6ec-900e-e6a43e4f8b73@oracle.com
Link: https://lkml.kernel.org/r/20211007181918.136982-6-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The routines remove_hugetlb_page and destroy_compound_gigantic_page will
remove a gigantic page and make the set of base pages ready to be
returned to a lower level allocator. In the process of doing this, they
make all base pages reference counted.
The routine prep_compound_gigantic_page creates a gigantic page from a
set of base pages. It assumes that all these base pages are reference
counted.
During demotion, a gigantic page will be split into huge pages of a
smaller size. This logically involves use of the routines,
remove_hugetlb_page, and destroy_compound_gigantic_page followed by
prep_compound*_page for each smaller huge page.
When pages are reference counted (ref count >= 0), additional
speculative ref counts could be taken as described in previous commits
[1] and [2]. This could result in errors while demoting a huge page.
Quite a bit of code would need to be created to handle all possible
issues.
Instead of dealing with the possibility of speculative ref counts, avoid
the possibility by keeping ref counts at zero during the demote process.
Add a boolean 'demote' to the routines remove_hugetlb_page,
destroy_compound_gigantic_page and prep_compound_gigantic_page. If the
boolean is set, the remove and destroy routines will not reference count
pages and the prep routine will not expect reference counted pages.
'*_for_demote' wrappers of the routines will be added in a subsequent
patch where this functionality is used.
[1] https://lore.kernel.org/linux-mm/20210622021423.154662-3-mike.kravetz@oracle.com/
[2] https://lore.kernel.org/linux-mm/20210809184832.18342-3-mike.kravetz@oracle.com/
Link: https://lkml.kernel.org/r/20211007181918.136982-5-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When huge page demotion is fully implemented, gigantic pages can be
demoted to a smaller huge page size. For example, on x86 a 1G page can
be demoted to 512 2M pages. However, gigantic pages can potentially be
allocated from CMA. If a gigantic page which was allocated from CMA is
demoted, the corresponding demoted pages needs to be returned to CMA.
Use the new interface cma_pages_valid() to determine if a non-gigantic
hugetlb page should be freed to CMA. Also, clear mapping field of these
pages as expected by cma_release.
This also requires a change to CMA region creation for gigantic pages.
CMA uses a per-region bit map to track allocations. When setting up the
region, you specify how many pages each bit represents. Currently, only
gigantic pages are allocated/freed from CMA so the region is set up such
that one bit represents a gigantic page size allocation.
With demote, a gigantic page (allocation) could be split into smaller
size pages. And, these smaller size pages will be freed to CMA. So,
since the per-region bit map needs to be set up to represent the
smallest allocation/free size, it now needs to be set to the smallest
huge page size which can be freed to CMA.
Unfortunately, we set up the CMA region for huge pages before we set up
huge pages sizes (hstates). So, technically we do not know the smallest
huge page size as this can change via command line options and
architecture specific code. Therefore, at region setup time we use
HUGETLB_PAGE_ORDER as the smallest possible huge page size that can be
given back to CMA. It is possible that this value is sub-optimal for
some architectures/config options. If needed, this can be addressed in
follow on work.
Link: https://lkml.kernel.org/r/20211007181918.136982-4-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add new interface cma_pages_valid() which indicates if the specified
pages are part of a CMA region. This interface will be used in a
subsequent patch by hugetlb code.
In order to keep the same amount of DEBUG information, a pr_debug() call
was added to cma_pages_valid(). In the case where the page passed to
cma_release is not in cma region, the debug message will be printed from
cma_pages_valid as opposed to cma_release.
Link: https://lkml.kernel.org/r/20211007181918.136982-3-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "hugetlb: add demote/split page functionality", v4.
The concurrent use of multiple hugetlb page sizes on a single system is
becoming more common. One of the reasons is better TLB support for
gigantic page sizes on x86 hardware. In addition, hugetlb pages are
being used to back VMs in hosting environments.
When using hugetlb pages to back VMs, it is often desirable to
preallocate hugetlb pools. This avoids the delay and uncertainty of
allocating hugetlb pages at VM startup. In addition, preallocating huge
pages minimizes the issue of memory fragmentation that increases the
longer the system is up and running.
In such environments, a combination of larger and smaller hugetlb pages
are preallocated in anticipation of backing VMs of various sizes. Over
time, the preallocated pool of smaller hugetlb pages may become depleted
while larger hugetlb pages still remain. In such situations, it is
desirable to convert larger hugetlb pages to smaller hugetlb pages.
Converting larger to smaller hugetlb pages can be accomplished today by
first freeing the larger page to the buddy allocator and then allocating
the smaller pages. For example, to convert 50 GB pages on x86:
gb_pages=`cat .../hugepages-1048576kB/nr_hugepages`
m2_pages=`cat .../hugepages-2048kB/nr_hugepages`
echo $(($gb_pages - 50)) > .../hugepages-1048576kB/nr_hugepages
echo $(($m2_pages + 25600)) > .../hugepages-2048kB/nr_hugepages
On an idle system this operation is fairly reliable and results are as
expected. The number of 2MB pages is increased as expected and the time
of the operation is a second or two.
However, when there is activity on the system the following issues
arise:
1) This process can take quite some time, especially if allocation of
the smaller pages is not immediate and requires migration/compaction.
2) There is no guarantee that the total size of smaller pages allocated
will match the size of the larger page which was freed. This is
because the area freed by the larger page could quickly be
fragmented.
In a test environment with a load that continually fills the page cache
with clean pages, results such as the following can be observed:
Unexpected number of 2MB pages allocated: Expected 25600, have 19944
real 0m42.092s
user 0m0.008s
sys 0m41.467s
To address these issues, introduce the concept of hugetlb page demotion.
Demotion provides a means of 'in place' splitting of a hugetlb page to
pages of a smaller size. This avoids freeing pages to buddy and then
trying to allocate from buddy.
Page demotion is controlled via sysfs files that reside in the per-hugetlb
page size and per node directories.
- demote_size
Target page size for demotion, a smaller huge page size. File
can be written to chose a smaller huge page size if multiple are
available.
- demote
Writable number of hugetlb pages to be demoted
To demote 50 GB huge pages, one would:
cat .../hugepages-1048576kB/free_hugepages /* optional, verify free pages */
cat .../hugepages-1048576kB/demote_size /* optional, verify target size */
echo 50 > .../hugepages-1048576kB/demote
Only hugetlb pages which are free at the time of the request can be
demoted. Demotion does not add to the complexity of surplus pages and
honors reserved huge pages. Therefore, when a value is written to the
sysfs demote file, that value is only the maximum number of pages which
will be demoted. It is possible fewer will actually be demoted. The
recently introduced per-hstate mutex is used to synchronize demote
operations with other operations that modify hugetlb pools.
Real world use cases
--------------------
The above scenario describes a real world use case where hugetlb pages
are used to back VMs on x86. Both issues of long allocation times and
not necessarily getting the expected number of smaller huge pages after
a free and allocate cycle have been experienced. The occurrence of
these issues is dependent on other activity within the host and can not
be predicted.
This patch (of 5):
Two new sysfs files are added to demote hugtlb pages. These files are
both per-hugetlb page size and per node. Files are:
demote_size - The size in Kb that pages are demoted to. (read-write)
demote - The number of huge pages to demote. (write-only)
By default, demote_size is the next smallest huge page size. Valid huge
page sizes less than huge page size may be written to this file. When
huge pages are demoted, they are demoted to this size.
Writing a value to demote will result in an attempt to demote that
number of hugetlb pages to an appropriate number of demote_size pages.
NOTE: Demote interfaces are only provided for huge page sizes if there
is a smaller target demote huge page size. For example, on x86 1GB huge
pages will have demote interfaces. 2MB huge pages will not have demote
interfaces.
This patch does not provide full demote functionality. It only provides
the sysfs interfaces.
It also provides documentation for the new interfaces.
[mike.kravetz@oracle.com: n_mask initialization does not need to be protected by the mutex]
Link: https://lkml.kernel.org/r/0530e4ef-2492-5186-f919-5db68edea654@oracle.com
Link: https://lkml.kernel.org/r/20211007181918.136982-2-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: David Rientjes <rientjes@google.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Nghia Le <nghialm78@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove __unmap_hugepage_range() from the header file, because it is only
used in hugetlb.c.
Link: https://lkml.kernel.org/r/20210917165108.9341-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently hwpoison doesn't handle non-anonymous THP, but since v4.8 THP
support for tmpfs and read-only file cache has been added. They could
be offlined by split THP, just like anonymous THP.
Link: https://lkml.kernel.org/r/20211020210755.23964-7-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current behavior of memory failure is to truncate the page cache
regardless of dirty or clean. If the page is dirty the later access
will get the obsolete data from disk without any notification to the
users. This may cause silent data loss. It is even worse for shmem
since shmem is in-memory filesystem, truncating page cache means
discarding data blocks. The later read would return all zero.
The right approach is to keep the corrupted page in page cache, any
later access would return error for syscalls or SIGBUS for page fault,
until the file is truncated, hole punched or removed. The regular
storage backed filesystems would be more complicated so this patch is
focused on shmem. This also unblock the support for soft offlining
shmem THP.
[arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()]
Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memory failure will report failure if the page still has extra pinned
refcount other than from hwpoison after the handler is done. Actually
the check is not necessary for all handlers, so move the check into
specific handlers. This would make the following keeping shmem page in
page cache patch easier.
There may be expected extra pin for some cases, for example, when the
page is dirty and in swapcache.
Link: https://lkml.kernel.org/r/20211020210755.23964-5-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Solve silent data loss caused by poisoned page cache (shmem/tmpfs)", v5.
When discussing the patch that splits page cache THP in order to offline
the poisoned page, Noaya mentioned there is a bigger problem [1] that
prevents this from working since the page cache page will be truncated
if uncorrectable errors happen. By looking this deeper it turns out
this approach (truncating poisoned page) may incur silent data loss for
all non-readonly filesystems if the page is dirty. It may be worse for
in-memory filesystem, e.g. shmem/tmpfs since the data blocks are
actually gone.
To solve this problem we could keep the poisoned dirty page in page
cache then notify the users on any later access, e.g. page fault,
read/write, etc. The clean page could be truncated as is since they can
be reread from disk later on.
The consequence is the filesystems may find poisoned page and manipulate
it as healthy page since all the filesystems actually don't check if the
page is poisoned or not in all the relevant paths except page fault. In
general, we need make the filesystems be aware of poisoned page before
we could keep the poisoned page in page cache in order to solve the data
loss problem.
To make filesystems be aware of poisoned page we should consider:
- The page should be not written back: clearing dirty flag could
prevent from writeback.
- The page should not be dropped (it shows as a clean page) by drop
caches or other callers: the refcount pin from hwpoison could prevent
from invalidating (called by cache drop, inode cache shrinking, etc),
but it doesn't avoid invalidation in DIO path.
- The page should be able to get truncated/hole punched/unlinked: it
works as it is.
- Notify users when the page is accessed, e.g. read/write, page fault
and other paths (compression, encryption, etc).
The scope of the last one is huge since almost all filesystems need do
it once a page is returned from page cache lookup. There are a couple
of options to do it:
1. Check hwpoison flag for every path, the most straightforward way.
2. Return NULL for poisoned page from page cache lookup, the most
callsites check if NULL is returned, this should have least work I
think. But the error handling in filesystems just return -ENOMEM,
the error code will incur confusion to the users obviously.
3. To improve #2, we could return error pointer, e.g. ERR_PTR(-EIO),
but this will involve significant amount of code change as well
since all the paths need check if the pointer is ERR or not just
like option #1.
I did prototypes for both #1 and #3, but it seems #3 may require more
changes than #1. For #3 ERR_PTR will be returned so all the callers
need to check the return value otherwise invalid pointer may be
dereferenced, but not all callers really care about the content of the
page, for example, partial truncate which just sets the truncated range
in one page to 0. So for such paths it needs additional modification if
ERR_PTR is returned. And if the callers have their own way to handle
the problematic pages we need to add a new FGP flag to tell FGP
functions to return the pointer to the page.
It may happen very rarely, but once it happens the consequence (data
corruption) could be very bad and it is very hard to debug. It seems
this problem had been slightly discussed before, but seems no action was
taken at that time. [2]
As the aforementioned investigation, it needs huge amount of work to
solve the potential data loss for all filesystems. But it is much
easier for in-memory filesystems and such filesystems actually suffer
more than others since even the data blocks are gone due to truncating.
So this patchset starts from shmem/tmpfs by taking option #1.
TODO:
* The unpoison has been broken since commit 0ed950d1f2 ("mm,hwpoison: make
get_hwpoison_page() call get_any_page()"), and this patch series make
refcount check for unpoisoning shmem page fail.
* Expand to other filesystems. But I haven't heard feedback from filesystem
developers yet.
Patch breakdown:
Patch #1: cleanup, depended by patch #2
Patch #2: fix THP with hwpoisoned subpage(s) PMD map bug
Patch #3: coding style cleanup
Patch #4: refactor and preparation.
Patch #5: keep the poisoned page in page cache and handle such case for all
the paths.
Patch #6: the previous patches unblock page cache THP split, so this patch
add page cache THP split support.
This patch (of 4):
A minor cleanup to the indent.
Link: https://lkml.kernel.org/r/20211020210755.23964-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20211020210755.23964-4-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only usage of hwp_walk_ops is to pass its address to
walk_page_range() which takes a pointer to const mm_walk_ops as
argument.
Make it const to allow the compiler to put it in read-only memory.
Link: https://lkml.kernel.org/r/20211014075042.17174-3-rikard.falkeborn@gmail.com
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch uses clamp() to simplify code in init_per_zone_wmark_min().
Link: https://lkml.kernel.org/r/20211021034830.1049150-1-bobo.shaobowang@huawei.com
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Cc: Li Bin <huawei.libin@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drain_local_pages_wq() disables preemption to avoid CPU migration during
CPU hotplug and can't use cpus_read_lock().
Using migrate_disable() works here, too. The scheduler won't take the
CPU offline until the task left the migrate-disable section. The
problem with disabled preemption here is that drain_local_pages()
acquires locks which are turned into sleeping locks on PREEMPT_RT and
can't be acquired with disabled preemption.
Use migrate_disable() in drain_local_pages_wq().
Link: https://lkml.kernel.org/r/20211015210933.viw6rjvo64qtqxn4@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
min/low/high_wmark_pages(z) is defined as
(z->_watermark[WMARK_MIN/LOW/HIGH] + z->watermark_boost)
If kswapd is frequently woken up due to the increase of
min/low/high_wmark_pages, printing watermark_boost can quickly locate
whether watermark_boost or _watermark[WMARK_MIN/LOW/HIGH] caused
min/low/high_wmark_pages to increase.
Link: https://lkml.kernel.org/r/1632472566-12246-1-git-send-email-liangcaifan19@gmail.com
Signed-off-by: Liangcai Fan <liangcaifan19@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There was a report that starting an Ubuntu in docker while using cpuset
to bind it to movable nodes (a node only has movable zone, like a node
for hotplug or a Persistent Memory node in normal usage) will fail due
to memory allocation failure, and then OOM is involved and many other
innocent processes got killed.
It can be reproduced with command:
$ docker run -it --rm --cpuset-mems 4 ubuntu:latest bash -c "grep Mems_allowed /proc/self/status"
(where node 4 is a movable node)
runc:[2:INIT] invoked oom-killer: gfp_mask=0x500cc2(GFP_HIGHUSER|__GFP_ACCOUNT), order=0, oom_score_adj=0
CPU: 8 PID: 8291 Comm: runc:[2:INIT] Tainted: G W I E 5.8.2-0.g71b519a-default #1 openSUSE Tumbleweed (unreleased)
Hardware name: Dell Inc. PowerEdge R640/0PHYDR, BIOS 2.6.4 04/09/2020
Call Trace:
dump_stack+0x6b/0x88
dump_header+0x4a/0x1e2
oom_kill_process.cold+0xb/0x10
out_of_memory.part.0+0xaf/0x230
out_of_memory+0x3d/0x80
__alloc_pages_slowpath.constprop.0+0x954/0xa20
__alloc_pages_nodemask+0x2d3/0x300
pipe_write+0x322/0x590
new_sync_write+0x196/0x1b0
vfs_write+0x1c3/0x1f0
ksys_write+0xa7/0xe0
do_syscall_64+0x52/0xd0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Mem-Info:
active_anon:392832 inactive_anon:182 isolated_anon:0
active_file:68130 inactive_file:151527 isolated_file:0
unevictable:2701 dirty:0 writeback:7
slab_reclaimable:51418 slab_unreclaimable:116300
mapped:45825 shmem:735 pagetables:2540 bounce:0
free:159849484 free_pcp:73 free_cma:0
Node 4 active_anon:1448kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB all_unreclaimable? no
Node 4 Movable free:130021408kB min:9140kB low:139160kB high:269180kB reserved_highatomic:0KB active_anon:1448kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:130023424kB managed:130023424kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:292kB local_pcp:84kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0 0
Node 4 Movable: 1*4kB (M) 0*8kB 0*16kB 1*32kB (M) 0*64kB 0*128kB 1*256kB (M) 1*512kB (M) 1*1024kB (M) 0*2048kB 31743*4096kB (M) = 130021156kB
oom-kill:constraint=CONSTRAINT_CPUSET,nodemask=(null),cpuset=docker-9976a269caec812c134fa317f27487ee36e1129beba7278a463dd53e5fb9997b.scope,mems_allowed=4,global_oom,task_memcg=/system.slice/containerd.service,task=containerd,pid=4100,uid=0
Out of memory: Killed process 4100 (containerd) total-vm:4077036kB, anon-rss:51184kB, file-rss:26016kB, shmem-rss:0kB, UID:0 pgtables:676kB oom_score_adj:0
oom_reaper: reaped process 8248 (docker), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 2054 (node_exporter), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 1452 (systemd-journal), now anon-rss:0kB, file-rss:8564kB, shmem-rss:4kB
oom_reaper: reaped process 2146 (munin-node), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 8291 (runc:[2:INIT]), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
The reason is that in this case, the target cpuset nodes only have
movable zone, while the creation of an OS in docker sometimes needs to
allocate memory in non-movable zones (dma/dma32/normal) like
GFP_HIGHUSER, and the cpuset limit forbids the allocation, then
out-of-memory killing is involved even when normal nodes and movable
nodes both have many free memory.
The OOM killer cannot help to resolve the situation as there is no
usable memory for the request in the cpuset scope. The only reasonable
measure to take is to fail the allocation right away and have the caller
to deal with it.
So add a check for cases like this in the slowpath of allocation, and
bail out early returning NULL for the allocation.
As page allocation is one of the hottest path in kernel, this check will
hurt all users with sane cpuset configuration, add a static branch check
and detect the abnormal config in cpuset memory binding setup so that
the extra check cost in page allocation is not paid by everyone.
[thanks to Micho Hocko and David Rientjes for suggesting not handling
it inside OOM code, adding cpuset check, refining comments]
Link: https://lkml.kernel.org/r/1632481657-68112-1-git-send-email-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Grabbing zone lock in is_free_buddy_page() gives a wrong sense of
safety, and has potential performance implications when zone is
experiencing lock contention.
In any case, if a caller needs a stable result, it should grab zone lock
before calling this function.
Link: https://lkml.kernel.org/r/20210922152833.4023972-1-eric.dumazet@gmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If CONFIG_NUMA=y, but CONFIG_SMP=n (e.g. sh/migor_defconfig):
sh4-linux-gnu-ld: mm/vmstat.o: in function `vmstat_start': vmstat.c:(.text+0x97c): undefined reference to `fold_vm_numa_events'
sh4-linux-gnu-ld: drivers/base/node.o: in function `node_read_vmstat': node.c:(.text+0x140): undefined reference to `fold_vm_numa_events'
sh4-linux-gnu-ld: drivers/base/node.o: in function `node_read_numastat': node.c:(.text+0x1d0): undefined reference to `fold_vm_numa_events'
Fix this by moving fold_vm_numa_events() outside the SMP-only section.
Link: https://lkml.kernel.org/r/9d16ccdd9ef32803d7100c84f737de6a749314fb.1631781495.git.geert+renesas@glider.be
Fixes: f19298b951 ("mm/vmstat: convert NUMA statistics to basic NUMA counters")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Gon Solo <gonsolo@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Fix NUMA without SMP".
SuperH is the only architecture which still supports NUMA without SMP,
for good reasons (various memories scattered around the address space,
each with varying latencies).
This series fixes two build errors due to variables and functions used
by the NUMA code being provided by SMP-only source files or sections.
This patch (of 2):
If CONFIG_NUMA=y, but CONFIG_SMP=n (e.g. sh/migor_defconfig):
sh4-linux-gnu-ld: mm/page_alloc.o: in function `get_page_from_freelist':
page_alloc.c:(.text+0x2c24): undefined reference to `node_reclaim_distance'
Fix this by moving the declaration of node_reclaim_distance from an
SMP-only to a generic file.
Link: https://lkml.kernel.org/r/cover.1631781495.git.geert+renesas@glider.be
Link: https://lkml.kernel.org/r/6432666a648dde85635341e6c918cee97c97d264.1631781495.git.geert+renesas@glider.be
Fixes: a55c7454a8 ("sched/topology: Improve load balancing on AMD EPYC systems")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Suggested-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Rich Felker <dalias@libc.org>
Cc: Gon Solo <gonsolo@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In build_zonelists(), when the fallback list is built for the nodes, the
node load gets reinitialized during each iteration. This results in
nodes with same distances occupying the same slot in different node
fallback lists rather than appearing in the intended round- robin
manner. This results in one node getting picked for allocation more
compared to other nodes with the same distance.
As an example, consider a 4 node system with the following distance
matrix.
Node 0 1 2 3
----------------
0 10 12 32 32
1 12 10 32 32
2 32 32 10 12
3 32 32 12 10
For this case, the node fallback list gets built like this:
Node Fallback list
---------------------
0 0 1 2 3
1 1 0 3 2
2 2 3 0 1
3 3 2 0 1 <-- Unexpected fallback order
In the fallback list for nodes 2 and 3, the nodes 0 and 1 appear in the
same order which results in more allocations getting satisfied from node
0 compared to node 1.
The effect of this on remote memory bandwidth as seen by stream
benchmark is shown below:
Case 1: Bandwidth from cores on nodes 2 & 3 to memory on nodes 0 & 1
(numactl -m 0,1 ./stream_lowOverhead ... --cores <from 2, 3>)
Case 2: Bandwidth from cores on nodes 0 & 1 to memory on nodes 2 & 3
(numactl -m 2,3 ./stream_lowOverhead ... --cores <from 0, 1>)
----------------------------------------
BANDWIDTH (MB/s)
TEST Case 1 Case 2
----------------------------------------
COPY 57479.6 110791.8
SCALE 55372.9 105685.9
ADD 50460.6 96734.2
TRIADD 50397.6 97119.1
----------------------------------------
The bandwidth drop in Case 1 occurs because most of the allocations get
satisfied by node 0 as it appears first in the fallback order for both
nodes 2 and 3.
This can be fixed by accumulating the node load in build_zonelists()
rather than reinitializing it during each iteration. With this the
nodes with the same distance rightly get assigned in the round robin
manner.
In fact this was how it was originally until commit f0c0b2b808
("change zonelist order: zonelist order selection logic") dropped the
load accumulation and resorted to initializing the load during each
iteration.
While zonelist ordering was removed by commit c9bff3eebc ("mm,
page_alloc: rip out ZONELIST_ORDER_ZONE"), the change to the node load
accumulation in build_zonelists() remained. So essentially this patch
reverts back to the accumulated node load logic.
After this fix, the fallback order gets built like this:
Node Fallback list
------------------
0 0 1 2 3
1 1 0 3 2
2 2 3 0 1
3 3 2 1 0 <-- Note the change here
The bandwidth in Case 1 improves and matches Case 2 as shown below.
----------------------------------------
BANDWIDTH (MB/s)
TEST Case 1 Case 2
----------------------------------------
COPY 110438.9 110107.2
SCALE 105930.5 105817.5
ADD 97005.1 96159.8
TRIADD 97441.5 96757.1
----------------------------------------
The correctness of the fallback list generation has been verified for
the above node configuration where the node 3 starts as memory-less node
and comes up online only during memory hotplug.
[bharata@amd.com: Added changelog, review, test validation]
Link: https://lkml.kernel.org/r/20210830121603.1081-3-bharata@amd.com
Fixes: f0c0b2b808 ("change zonelist order: zonelist order selection logic")
Signed-off-by: Krupa Ramakrishnan <krupa.ramakrishnan@amd.com>
Co-developed-by: Sadagopan Srinivasan <Sadagopan.Srinivasan@amd.com>
Signed-off-by: Sadagopan Srinivasan <Sadagopan.Srinivasan@amd.com>
Signed-off-by: Bharata B Rao <bharata@amd.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Fix NUMA nodes fallback list ordering".
For a NUMA system that has multiple nodes at same distance from other
nodes, the fallback list generation prefers same node order for them
instead of round-robin thereby penalizing one node over others. This
series fixes it.
More description of the problem and the fix is present in the patch
description.
This patch (of 2):
Print information message about the allocation fallback order for each
NUMA node during boot.
No functional changes here. This makes it easier to illustrate the
problem in the node fallback list generation, which the next patch
fixes.
Link: https://lkml.kernel.org/r/20210830121603.1081-1-bharata@amd.com
Link: https://lkml.kernel.org/r/20210830121603.1081-2-bharata@amd.com
Signed-off-by: Bharata B Rao <bharata@amd.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Krupa Ramakrishnan <krupa.ramakrishnan@amd.com>
Cc: Sadagopan Srinivasan <Sadagopan.Srinivasan@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't use with __GFP_HIGHMEM because page_address() cannot represent
highmem pages without kmap(). Newly allocated pages would leak as
page_address() will return NULL for highmem pages here. But It works
now because the callers do not specify __GFP_HIGHMEM now.
Link: https://lkml.kernel.org/r/20210902121242.41607-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use helper function zone_spans_pfn() to check whether pfn is within a
zone to simplify the code slightly.
Link: https://lkml.kernel.org/r/20210902121242.41607-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The second two paragraphs about "all pages pinned" and pages_scanned is
obsolete. And There are PAGE_ALLOC_COSTLY_ORDER + 1 + NR_PCP_THP orders
in pcp. So the same order assumption is not held now.
Link: https://lkml.kernel.org/r/20210902121242.41607-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use helper macro K() to convert the pages to the corresponding size.
Minor readability improvement.
Link: https://lkml.kernel.org/r/20210902121242.41607-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Cleanups and fixup for page_alloc", v2.
This series contains cleanups to remove meaningless VM_BUG_ON(), use
helpers to simplify the code and remove obsolete comment. Also we avoid
allocating highmem pages via alloc_pages_exact[_nid]. More details can be
found in the respective changelogs.
This patch (of 5):
It's meaningless to VM_BUG_ON() order != pageblock_order just after
setting order to pageblock_order. Remove it.
Link: https://lkml.kernel.org/r/20210902121242.41607-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210902121242.41607-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If __vmalloc() returned NULL, is_vm_area_hugepages(NULL) will fault if
CONFIG_HAVE_ARCH_HUGE_VMALLOC=y
Link: https://lkml.kernel.org/r/20210915212530.2321545-1-eric.dumazet@gmail.com
Fixes: 121e6f3258 ("mm/vmalloc: hugepage vmalloc mappings")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit ffb29b1c25 ("mm/vmalloc: fix numa spreading for large hash
tables") can cause significant performance regressions in some
situations as Andrew mentioned in [1]. The main situation is vmalloc,
vmalloc will allocate pages with NUMA_NO_NODE by default, that will
result in alloc page one by one;
In order to solve this, __alloc_pages_bulk and mempolicy should be
considered at the same time.
1) If node is specified in memory allocation request, it will alloc all
pages by __alloc_pages_bulk.
2) If interleaving allocate memory, it will cauculate how many pages
should be allocated in each node, and use __alloc_pages_bulk to alloc
pages in each node.
[1]: https://lore.kernel.org/lkml/CALvZod4G3SzP3kWxQYn0fj+VgG-G3yWXz=gz17+3N57ru1iajw@mail.gmail.com/t/#m750c8e3231206134293b089feaa090590afa0f60
[akpm@linux-foundation.org: coding style fixes]
[akpm@linux-foundation.org: make two functions static]
[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
Link: https://lkml.kernel.org/r/20211021080744.874701-3-chenwandun@huawei.com
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The core of the vmalloc allocator __vmalloc_area_node doesn't say
anything about gfp mask argument. Not all gfp flags are supported
though. Be more explicit about constraints.
Link: https://lkml.kernel.org/r/20211020082545.4830-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Percpu embedded first chunk allocator is the firstly option, but it
could fail on ARM64, eg,
percpu: max_distance=0x5fcfdc640000 too large for vmalloc space 0x781fefff0000
percpu: max_distance=0x600000540000 too large for vmalloc space 0x7dffb7ff0000
percpu: max_distance=0x5fff9adb0000 too large for vmalloc space 0x5dffb7ff0000
then we could get to
WARNING: CPU: 15 PID: 461 at vmalloc.c:3087 pcpu_get_vm_areas+0x488/0x838
and the system cannot boot successfully.
Let's implement page mapping percpu first chunk allocator as a fallback
to the embedding allocator to increase the robustness of the system.
Also fix a crash when both NEED_PER_CPU_PAGE_FIRST_CHUNK and
KASAN_VMALLOC enabled.
Tested on ARM64 qemu with cmdline "percpu_alloc=page".
This patch (of 3):
There are some fixed locations in the vmalloc area be reserved in
ARM(see iotable_init()) and ARM64(see map_kernel()), but for
pcpu_page_first_chunk(), it calls vm_area_register_early() and choose
VMALLOC_START as the start address of vmap area which could be
conflicted with above address, then could trigger a BUG_ON in
vm_area_add_early().
Let's choose a suit start address by traversing the vmlist.
Link: https://lkml.kernel.org/r/20210910053354.26721-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20210910053354.26721-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Huge vmalloc allocation on heavy loaded node can lead to a global memory
shortage. Task called vmalloc can have worst badness and be selected by
OOM-killer, however taken fatal signal does not interrupt allocation
cycle. Vmalloc repeat page allocaions again and again, exacerbating the
crisis and consuming the memory freed up by another killed tasks.
After a successful completion of the allocation procedure, a fatal
signal will be processed and task will be destroyed finally. However it
may not release the consumed memory, since the allocated object may have
a lifetime unrelated to the completed task. In the worst case, this can
lead to the host will panic due to "Out of memory and no killable
processes..."
This patch allows OOM-killer to break vmalloc cycle, makes OOM more
effective and avoid host panic. It does not check oom condition
directly, however, and breaks page allocation cycle when fatal signal
was received.
This may trigger some hidden problems, when caller does not handle
vmalloc failures, or when rollaback after failed vmalloc calls own
vmallocs inside. However all of these scenarios are incorrect: vmalloc
does not guarantee successful allocation, it has never been called with
__GFP_NOFAIL and threfore either should not be used for any rollbacks or
should handle such errors correctly and not lead to critical failures.
Link: https://lkml.kernel.org/r/83efc664-3a65-2adb-d7c4-2885784cf109@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before we did not guarantee a free block with lowest start address for
allocations with alignment >= PAGE_SIZE. Because an alignment overhead
was included into a search length like below:
length = size + align - 1;
doing so we make sure that a bigger block would fit after applying an
alignment adjustment. Now there is no such limitation, i.e. any
alignment that user wants to apply will result to a lowest address of
returned free area.
Link: https://lkml.kernel.org/r/20211004142829.22222-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Ping Fang <pifang@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We used to include an alignment overhead into a search length, in that
case we guarantee that a found area will definitely fit after applying a
specific alignment that user specifies. From the other hand we do not
guarantee that an area has the lowest address if an alignment is >=
PAGE_SIZE.
It means that, when a user specifies a special alignment together with a
range that corresponds to an exact requested size then an allocation
will fail. This is what happens to KASAN, it wants the free block that
exactly matches a specified range during onlining memory banks:
[root@vm-0 fedora]# echo online > /sys/devices/system/memory/memory82/state
[root@vm-0 fedora]# echo online > /sys/devices/system/memory/memory83/state
[root@vm-0 fedora]# echo online > /sys/devices/system/memory/memory85/state
[root@vm-0 fedora]# echo online > /sys/devices/system/memory/memory84/state
vmap allocation for size 16777216 failed: use vmalloc=<size> to increase size
bash: vmalloc: allocation failure: 16777216 bytes, mode:0x6000c0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 4 PID: 1644 Comm: bash Kdump: loaded Not tainted 4.18.0-339.el8.x86_64+debug #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8e/0xd0
warn_alloc.cold.90+0x8a/0x1b2
? zone_watermark_ok_safe+0x300/0x300
? slab_free_freelist_hook+0x85/0x1a0
? __get_vm_area_node+0x240/0x2c0
? kfree+0xdd/0x570
? kmem_cache_alloc_node_trace+0x157/0x230
? notifier_call_chain+0x90/0x160
__vmalloc_node_range+0x465/0x840
? mark_held_locks+0xb7/0x120
Fix it by making sure that find_vmap_lowest_match() returns lowest start
address with any given alignment value, i.e. for alignments bigger then
PAGE_SIZE the algorithm rolls back toward parent nodes checking right
sub-trees if the most left free block did not fit due to alignment
overhead.
Link: https://lkml.kernel.org/r/20211004142829.22222-1-urezki@gmail.com
Fixes: 68ad4a3304 ("mm/vmalloc.c: keep track of free blocks for vmap allocation")
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reported-by: Ping Fang <pifang@redhat.com>
Tested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If last va found in vmap_area_list does not have a vm pointer,
vmallocinfo.s_show() returns 0, and show_purge_info() is not called as
it should.
Link: https://lkml.kernel.org/r/20211001170815.73321-1-eric.dumazet@gmail.com
Fixes: dd3b8353ba ("mm/vmalloc: do not keep unpurged areas in the busy tree")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Pengfei Li <lpf.vector@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
show_numa_info() can be slightly faster, by skipping over hugepages
directly.
Link: https://lkml.kernel.org/r/20211001172725.105824-1-eric.dumazet@gmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vmalloc guard pages are added on top of each allocation, thereby
isolating any two allocations from one another. The top guard of the
lower allocation is the bottom guard guard of the higher allocation etc.
Therefore VM_NO_GUARD is dangerous; it breaks the basic premise of
isolating separate allocations.
There are only two in-tree users of this flag, neither of which use it
through the exported interface. Ensure it stays this way.
Link: https://lkml.kernel.org/r/YUMfdA36fuyZ+/xt@hirez.programming.kicks-ass.net
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit f255935b97 ("mm: cleanup the gfp_mask handling in
__vmalloc_area_node") added __GFP_NOWARN to gfp_mask unconditionally
however it disabled all output inside warn_alloc() call. This patch
saves original gfp_mask and provides it to all warn_alloc() calls.
Link: https://lkml.kernel.org/r/f4f3187b-9684-e426-565d-827c2a9bbb0e@virtuozzo.com
Fixes: f255935b97 ("mm: cleanup the gfp_mask handling in __vmalloc_area_node")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All this vm_unacct_memory(charged) dance seems to complicate the life
without a good reason. Furthermore, it seems not always done right on
error-pathes in mremap_to(). And worse than that: this `charged'
difference is sometimes double-accounted for growing MREMAP_DONTUNMAP
mremap()s in move_vma():
if (security_vm_enough_memory_mm(mm, new_len >> PAGE_SHIFT))
Let's not do this. Account memory in mremap() fast-path for growing
VMAs or in move_vma() for actually moving things. The same simpler way
as it's done by vm_stat_account(), but with a difference to call
security_vm_enough_memory_mm() before copying/adjusting VMA.
Originally noticed by Chen Wandun:
https://lkml.kernel.org/r/20210717101942.120607-1-chenwandun@huawei.com
Link: https://lkml.kernel.org/r/20210721131320.522061-1-dima@arista.com
Fixes: e346b38130 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After adjustment, the repeated assignment of "prev" is avoided, and the
readability of the code is improved.
Link: https://lkml.kernel.org/r/20211012152444.4127-1-fishland@aliyun.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The smp_wmb() which is in the __pte_alloc() is used to ensure all ptes
setup is visible before the pte is made visible to other CPUs by being
put into page tables. We only need this when the pte is actually
populated, so move it to pmd_install(). __pte_alloc_kernel(),
__p4d_alloc(), __pud_alloc() and __pmd_alloc() are similar to this case.
We can also defer smp_wmb() to the place where the pmd entry is really
populated by preallocated pte. There are two kinds of user of
preallocated pte, one is filemap & finish_fault(), another is THP. The
former does not need another smp_wmb() because the smp_wmb() has been
done by pmd_install(). Fortunately, the latter also does not need
another smp_wmb() because there is already a smp_wmb() before populating
the new pte when the THP uses a preallocated pte to split a huge pmd.
Link: https://lkml.kernel.org/r/20210901102722.47686-3-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mika Penttila <mika.penttila@nextfour.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Do some code cleanups related to mm", v3.
This patch (of 2):
Currently we have three times the same few lines repeated in the code.
Deduplicate them by newly introduced pmd_install() helper.
Link: https://lkml.kernel.org/r/20210901102722.47686-1-zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/20210901102722.47686-2-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mika Penttila <mika.penttila@nextfour.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the helper for the checks. Rename "check_mapping" into
"zap_mapping" because "check_mapping" looks like a bool but in fact it
stores the mapping itself. When it's set, we check the mapping (it must
be non-NULL). When it's cleared we skip the check, which works like the
old way.
Move the duplicated comments to the helper too.
Link: https://lkml.kernel.org/r/20210915181538.11288-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The first_index/last_index parameters in zap_details are actually only
used in unmap_mapping_range_tree(). At the meantime, this function is
only called by unmap_mapping_pages() once.
Instead of passing these two variables through the whole stack of page
zapping code, remove them from zap_details and let them simply be
parameters of unmap_mapping_range_tree(), which is inlined.
Link: https://lkml.kernel.org/r/20210915181535.11238-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pte_unmap_same() will always unmap the pte pointer. After the unmap,
vmf->pte will not be valid any more, we should clear it.
It was safe only because no one is accessing vmf->pte after
pte_unmap_same() returns, since the only caller of pte_unmap_same() (so
far) is do_swap_page(), where vmf->pte will in most cases be overwritten
very soon.
Directly pass in vmf into pte_unmap_same() and then we can also avoid
the long parameter list too, which should be a nice cleanup.
Link: https://lkml.kernel.org/r/20210915181533.11188-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: A few cleanup patches around zap, shmem and uffd", v4.
IMHO all of them are very nice cleanups to existing code already,
they're all small and self-contained. They'll be needed by uffd-wp
coming series.
This patch (of 4):
It was conditionally done previously, as there's one shmem special case
that we use SetPageDirty() instead. However that's not necessary and it
should be easier and cleaner to do it unconditionally in
mfill_atomic_install_pte().
The most recent discussion about this is here, where Hugh explained the
history of SetPageDirty() and why it's possible that it's not required
at all:
https://lore.kernel.org/lkml/alpine.LSU.2.11.2104121657050.1097@eggly.anvils/
Currently mfill_atomic_install_pte() has three callers:
1. shmem_mfill_atomic_pte
2. mcopy_atomic_pte
3. mcontinue_atomic_pte
After the change: case (1) should have its SetPageDirty replaced by the
dirty bit on pte (so we unify them together, finally), case (2) should
have no functional change at all as it has page_in_cache==false, case
(3) may add a dirty bit to the pte. However since case (3) is
UFFDIO_CONTINUE for shmem, it's merely 100% sure the page is dirty after
all because UFFDIO_CONTINUE normally requires another process to modify
the page cache and kick the faulted thread, so should not make a real
difference either.
This should make it much easier to follow on which case will set dirty
for uffd, as we'll simply set it all now for all uffd related ioctls.
Meanwhile, no special handling of SetPageDirty() if there's no need.
Link: https://lkml.kernel.org/r/20210915181456.10739-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20210915181456.10739-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Annotating a pointer from __user to kernel and then back again might
confuse sparse. In copy_huge_page_from_user() it can be avoided by
removing the intermediate variable since it is never used.
Link: https://lkml.kernel.org/r/20210914150820.19326-1-amit.kachhap@arm.com
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The variable mm->total_vm could be accessed concurrently during mmaping
and system accounting as noticed by KCSAN,
BUG: KCSAN: data-race in __acct_update_integrals / mmap_region
read-write to 0xffffa40267bd14c8 of 8 bytes by task 15609 on cpu 3:
mmap_region+0x6dc/0x1400
do_mmap+0x794/0xca0
vm_mmap_pgoff+0xdf/0x150
ksys_mmap_pgoff+0xe1/0x380
do_syscall_64+0x37/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffffa40267bd14c8 of 8 bytes by interrupt on cpu 2:
__acct_update_integrals+0x187/0x1d0
acct_account_cputime+0x3c/0x40
update_process_times+0x5c/0x150
tick_sched_timer+0x184/0x210
__run_hrtimer+0x119/0x3b0
hrtimer_interrupt+0x350/0xaa0
__sysvec_apic_timer_interrupt+0x7b/0x220
asm_call_irq_on_stack+0x12/0x20
sysvec_apic_timer_interrupt+0x4d/0x80
asm_sysvec_apic_timer_interrupt+0x12/0x20
smp_call_function_single+0x192/0x2b0
perf_install_in_context+0x29b/0x4a0
__se_sys_perf_event_open+0x1a98/0x2550
__x64_sys_perf_event_open+0x63/0x70
do_syscall_64+0x37/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reported by Kernel Concurrency Sanitizer on:
CPU: 2 PID: 15610 Comm: syz-executor.3 Not tainted 5.10.0+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Ubuntu-1.8.2-1ubuntu1 04/01/2014
In vm_stat_account which called by mmap_region, increase total_vm, and
__acct_update_integrals may read total_vm at the same time. This will
cause a data race which lead to undefined behaviour. To avoid potential
bad read/write, volatile property and barrier are both used to avoid
undefined behaviour.
Link: https://lkml.kernel.org/r/20210913105550.1569419-1-liupeng256@huawei.com
Signed-off-by: Peng Liu <liupeng256@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memory cgroup charging allows killed or exiting tasks to exceed the hard
limit. It is assumed that the amount of the memory charged by those
tasks is bound and most of the memory will get released while the task
is exiting. This is resembling a heuristic for the global OOM situation
when tasks get access to memory reserves. There is no global memory
shortage at the memcg level so the memcg heuristic is more relieved.
The above assumption is overly optimistic though. E.g. vmalloc can
scale to really large requests and the heuristic would allow that. We
used to have an early break in the vmalloc allocator for killed tasks
but this has been reverted by commit b8c8a338f7 ("Revert "vmalloc:
back off when the current task is killed""). There are likely other
similar code paths which do not check for fatal signals in an
allocation&charge loop. Also there are some kernel objects charged to a
memcg which are not bound to a process life time.
It has been observed that it is not really hard to trigger these
bypasses and cause global OOM situation.
One potential way to address these runaways would be to limit the amount
of excess (similar to the global OOM with limited oom reserves). This
is certainly possible but it is not really clear how much of an excess
is desirable and still protects from global OOMs as that would have to
consider the overall memcg configuration.
This patch is addressing the problem by removing the heuristic
altogether. Bypass is only allowed for requests which either cannot
fail or where the failure is not desirable while excess should be still
limited (e.g. atomic requests). Implementation wise a killed or dying
task fails to charge if it has passed the OOM killer stage. That should
give all forms of reclaim chance to restore the limit before the failure
(ENOMEM) and tell the caller to back off.
In addition, this patch renames should_force_charge() helper to
task_is_dying() because now its use is not associated witch forced
charging.
This patch depends on pagefault_out_of_memory() to not trigger
out_of_memory(), because then a memcg failure can unwind to VM_FAULT_OOM
and cause a global OOM killer.
Link: https://lkml.kernel.org/r/8f5cebbb-06da-4902-91f0-6566fc4b4203@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Any allocation failure during the #PF path will return with VM_FAULT_OOM
which in turn results in pagefault_out_of_memory. This can happen for 2
different reasons. a) Memcg is out of memory and we rely on
mem_cgroup_oom_synchronize to perform the memcg OOM handling or b)
normal allocation fails.
The latter is quite problematic because allocation paths already trigger
out_of_memory and the page allocator tries really hard to not fail
allocations. Anyway, if the OOM killer has been already invoked there
is no reason to invoke it again from the #PF path. Especially when the
OOM condition might be gone by that time and we have no way to find out
other than allocate.
Moreover if the allocation failed and the OOM killer hasn't been invoked
then we are unlikely to do the right thing from the #PF context because
we have already lost the allocation context and restictions and
therefore might oom kill a task from a different NUMA domain.
This all suggests that there is no legitimate reason to trigger
out_of_memory from pagefault_out_of_memory so drop it. Just to be sure
that no #PF path returns with VM_FAULT_OOM without allocation print a
warning that this is happening before we restart the #PF.
[VvS: #PF allocation can hit into limit of cgroup v1 kmem controller.
This is a local problem related to memcg, however, it causes unnecessary
global OOM kills that are repeated over and over again and escalate into a
real disaster. This has been broken since kmem accounting has been
introduced for cgroup v1 (3.8). There was no kmem specific reclaim for
the separate limit so the only way to handle kmem hard limit was to return
with ENOMEM. In upstream the problem will be fixed by removing the
outdated kmem limit, however stable and LTS kernels cannot do it and are
still affected. This patch fixes the problem and should be backported
into stable/LTS.]
Link: https://lkml.kernel.org/r/f5fd8dd8-0ad4-c524-5f65-920b01972a42@virtuozzo.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "memcg: prohibit unconditional exceeding the limit of dying tasks", v3.
Memory cgroup charging allows killed or exiting tasks to exceed the hard
limit. It can be misused and allowed to trigger global OOM from inside
a memcg-limited container. On the other hand if memcg fails allocation,
called from inside #PF handler it triggers global OOM from inside
pagefault_out_of_memory().
To prevent these problems this patchset:
(a) removes execution of out_of_memory() from
pagefault_out_of_memory(), becasue nobody can explain why it is
necessary.
(b) allow memcg to fail allocation of dying/killed tasks.
This patch (of 3):
Any allocation failure during the #PF path will return with VM_FAULT_OOM
which in turn results in pagefault_out_of_memory which in turn executes
out_out_memory() and can kill a random task.
An allocation might fail when the current task is the oom victim and
there are no memory reserves left. The OOM killer is already handled at
the page allocator level for the global OOM and at the charging level
for the memcg one. Both have much more information about the scope of
allocation/charge request. This means that either the OOM killer has
been invoked properly and didn't lead to the allocation success or it
has been skipped because it couldn't have been invoked. In both cases
triggering it from here is pointless and even harmful.
It makes much more sense to let the killed task die rather than to wake
up an eternally hungry oom-killer and send him to choose a fatter victim
for breakfast.
Link: https://lkml.kernel.org/r/0828a149-786e-7c06-b70a-52d086818ea3@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The non-memcg-aware lru is always skiped when traversing the global lru
list, which is not efficient. We can only add the memcg-aware lru to
the global lru list instead to make traversing more efficient.
Link: https://lkml.kernel.org/r/20211025124353.55781-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now the kmem states is only used to indicate whether the kmem is
offline. However, we can set ->kmemcg_id to -1 to indicate whether the
kmem is offline. Finally, we can remove the kmem states to simplify the
code.
Link: https://lkml.kernel.org/r/20211025125259.56624-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since slab objects and kmem pages are charged to object cgroup instead
of memory cgroup, memcg_reparent_objcgs() will reparent this cgroup and
all its descendants to its parent cgroup. This already makes further
list_lru_add()'s add elements to the parent's list. So it is
unnecessary to change kmemcg_id of an offline cgroup to its parent's id.
It just wastes CPU cycles. Just remove the redundant code.
Link: https://lkml.kernel.org/r/20211025125102.56533-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 2788cf0c40 ("memcg: reparent list_lrus and free kmemcg_id
on css offline"), ->nr_items can be negative during memory cgroup
reparenting. In this case, list_lru_count_one() will return an unusual
and huge value, which can surprise users. At least for now it hasn't
affected any users. But it is better to let list_lru_count_ont()
returns zero when ->nr_items is negative.
Link: https://lkml.kernel.org/r/20211025124910.56433-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit e5bc3af773 ("rcu: Consolidate PREEMPT and !PREEMPT
synchronize_rcu()"), the critical section of spin lock can serve as an
RCU read-side critical section which already allows readers that hold
nlru->lock to avoid taking rcu lock. So just remove holding lock.
Link: https://lkml.kernel.org/r/20211025124534.56345-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The deprecation process of kmem.limit_in_bytes started with the commit
0158115f70 ("memcg, kmem: deprecate kmem.limit_in_bytes") which also
explains in detail the motivation behind the deprecation. To summarize,
it is the unexpected behavior on hitting the kmem limit. This patch
moves the deprecation process to the next stage by disallowing to set
the kmem limit. In future we might just remove the kmem.limit_in_bytes
file completely.
[akpm@linux-foundation.org: s/ENOTSUPP/EOPNOTSUPP/]
[arnd@arndb.de: mark cancel_charge() inline]
Link: https://lkml.kernel.org/r/20211022070542.679839-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20211019153408.2916808-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing.
This could lead to values wrapping around and a smaller allocation being
made than the caller was expecting. Using those allocations could lead
to linear overflows of heap memory and other misbehaviors.
So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kvmalloc() functions.
Also, take the opportunity to refactor the memcpy() call to use the
flex_array_size() helper.
This code was detected with the help of Coccinelle and audited and fixed
manually.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
Link: https://lkml.kernel.org/r/20211017105929.9284-1-len.baker@gmx.com
Signed-off-by: Len Baker <len.baker@gmx.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit d648bcc7fe ("mm: kmem: make memcg_kmem_enabled()
irreversible"), the only thing memcg_free_kmem() does is to call
memcg_offline_kmem() when the memcg is still online which can happen
when online_css() fails due to -ENOMEM.
However, the name memcg_free_kmem() is confusing and it is more clear
and straight forward to call memcg_offline_kmem() directly from
mem_cgroup_css_free().
Link: https://lkml.kernel.org/r/20211005202450.11775-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Suggested-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memcg stats can be flushed in multiple context and potentially in
parallel too. For example multiple parallel user space readers for
memcg stats will contend on the rstat locks with each other. There is
no need for that. We just need one flusher and everyone else can
benefit.
In addition after aa48e47e39 ("memcg: infrastructure to flush memcg
stats") the kernel periodically flush the memcg stats from the root, so,
the other flushers will potentially have much less work to do.
Link: https://lkml.kernel.org/r/20211001190040.48086-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At the moment, the kernel flushes the memcg stats on every refault and
also on every reclaim iteration. Although rstat maintains per-cpu
update tree but on the flush the kernel still has to go through all the
cpu rstat update tree to check if there is anything to flush. This
patch adds the tracking on the stats update side to make flush side more
clever by skipping the flush if there is no update.
The stats update codepath is very sensitive performance wise for many
workloads and benchmarks. So, we can not follow what the commit
aa48e47e39 ("memcg: infrastructure to flush memcg stats") did which
was triggering async flush through queue_work() and caused a lot
performance regression reports. That got reverted by the commit
1f828223b7 ("memcg: flush lruvec stats in the refault").
In this patch we kept the stats update codepath very minimal and let the
stats reader side to flush the stats only when the updates are over a
specific threshold. For now the threshold is (nr_cpus * CHARGE_BATCH).
To evaluate the impact of this patch, an 8 GiB tmpfs file is created on
a system with swap-on-zram and the file was pushed to swap through
memory.force_empty interface. On reading the whole file, the memcg stat
flush in the refault code path is triggered. With this patch, we
observed 63% reduction in the read time of 8 GiB file.
Link: https://lkml.kernel.org/r/20211001190040.48086-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Reviewed-by: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is unused after the rework of commit f5df8635c5 ("mm: use
find_get_incore_page in memcontrol").
Link: https://lkml.kernel.org/r/20210916193014.80129-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of calling put_page() one page at a time, pop pages off the list
if their refcount was too high and pass the remainder to
put_unref_page_list(). This should be a speed improvement, but I have
no measurements to support that. Current callers do not care about
performance, but I hope to add some which do.
Link: https://lkml.kernel.org/r/20211007192138.561673-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This one is just a minor nuisance for people going through /proc/swaps
if any of their swapareas is bigger than, or equal to 1073741824 pages
(4TB).
seq_printf() format string casts as uint the conversion from pages to
KB, and that will overflow in the aforementioned case.
Albeit being almost unthinkable that someone would actually set up such
big of a single swaparea, there is a ticket recently filed against RHEL:
https://bugzilla.redhat.com/show_bug.cgi?id=2008812
Given that all other codesites that use format strings for the same swap
pages-to-KB conversion do cast it as ulong, this patch just follows
suit.
Link: https://lkml.kernel.org/r/20211006184011.2579054-1-aquini@redhat.com
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The request_queue pointer returned from bdev_get_queue() shall never be
NULL, so the null check is unnecessary, just remove it.
Link: https://lkml.kernel.org/r/20210917082111.33923-1-vulab@iscas.ac.cn
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 6401c4eb57 ("mm: gup: fix potential pgmap refcnt leak in
__gup_device_huge()") simplified the return paths, but didn't go quite
far enough, as discussed in [1].
Remove the "ret" variable entirely, because there is enough information
already available to provide the return value.
[1] https://lore.kernel.org/r/CAHk-=wgQTRX=5SkCmS+zfmpqubGHGJvXX_HgnPG8JSpHKHBMeg@mail.gmail.com
Link: https://lkml.kernel.org/r/20210904004224.86391-1-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The fast path here is not needing any writeback, yet we spend time
setting up the xarray lookup data upfront. Move the part that actually
needs to iterate the address space mapping into a separate helper,
saving ~30% of the time here.
Link: https://lkml.kernel.org/r/49f67983-b802-8929-edab-d807f745c9ca@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is not safe to check page->index without holding the page lock. It
can be changed if the page is moved between the swap cache and the page
cache for a shmem file, for example. There is a VM_BUG_ON below which
checks page->index is correct after taking the page lock.
Link: https://lkml.kernel.org/r/20210818144932.940640-1-willy@infradead.org
Fixes: 5c211ba29d ("mm: add and use find_lock_entries")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: <syzbot+c87be4f669d920c76330@syzkaller.appspotmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We always go through i_size_read(), and we rarely end up needing it.
Push the read to down where we need to check it, which avoids it for
most cases.
It looks like we can even remove this check entirely, which might be
worth pursuing. But at least this takes it out of the hot path.
Link: https://lkml.kernel.org/r/6b67981f-57d4-c80e-bc07-6020aa601381@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move grabbing and releasing the bdi refcount out of the common
wb_init/wb_exit helpers into code that is only used for the non-default
memcg driven bdi_writeback structures.
[hch@lst.de: add comment]
Link: https://lkml.kernel.org/r/20211027074207.GA12793@lst.de
[akpm@linux-foundation.org: fix typo]
Link: https://lkml.kernel.org/r/20211021124441.668816-6-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "simplify bdi unregistation".
This series simplifies the BDI code to get rid of the magic
auto-unregister feature that hid a recent block layer refcounting bug.
This patch (of 5):
To wind down the magic auto-unregister semantics we'll need to push this
into modular code.
Link: https://lkml.kernel.org/r/20211021124441.668816-1-hch@lst.de
Link: https://lkml.kernel.org/r/20211021124441.668816-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I have noticed that the previous macro is #ifndef CONFIG_SPARSEMEM. I
think the comment of #else should be CONFIG_SPARSEMEM.
Link: https://lkml.kernel.org/r/20211008140312.6492-1-zhangyinan2019@email.szu.edu.cn
Signed-off-by: Yinan Zhang <zhangyinan2019@email.szu.edu.cn>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __Pxxx/__Sxxx macros are only for protection_map[] init. All usage
of them in linux should come from protection_map array.
Because a lot of architectures would re-initilize protection_map[]
array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
Using __P000 is not rigorous.
Link: https://lkml.kernel.org/r/20210924060821.1138281-1-guoren@kernel.org
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As it's trying to cover the whole vma anyways, use direct vm_pgoff value
and vma_pages() rather than linear_page_index.
Link: https://lkml.kernel.org/r/20210917164756.8586-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If an object is allocated on a tail page of a multi-page slab, kasan
will get the wrong tag because page->s_mem is NULL for tail pages. I'm
not quite sure what the user-visible effect of this might be.
Link: https://lkml.kernel.org/r/20211001024105.3217339-1-willy@infradead.org
Fixes: 7f94ffbc4c ("kasan: add hooks implementation for tag-based mode")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a variant of kasan_record_aux_stack() that does not do any
memory allocation through stackdepot. This will permit using it in
contexts that cannot allocate any memory.
Link: https://lkml.kernel.org/r/20210913112609.2651084-6-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Tested-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Taras Madan <tarasmadan@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Not required at all, and having this causes a huge kernel rebuild as
soon as something in dax.h changes.
Link: https://lkml.kernel.org/r/20210921082253.1859794-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
TRANSPARENT_HUGEPAGE:
There are potential non-deterministic delays to an RT thread if a
critical memory region is not THP-aligned and a non-RT buffer is
located in the same hugepage-aligned region. It's also possible for an
unrelated thread to migrate pages belonging to an RT task incurring
unexpected page faults due to memory defragmentation even if
khugepaged is disabled.
Regular HUGEPAGEs are not affected by this can be used.
NUMA_BALANCING:
There is a non-deterministic delay to mark PTEs PROT_NONE to gather
NUMA fault samples, increased page faults of regions even if mlocked
and non-deterministic delays when migrating pages.
[Mel Gorman worded 99% of the commit description].
Link: https://lore.kernel.org/all/20200304091159.GN3818@techsingularity.net/
Link: https://lore.kernel.org/all/20211026165100.ahz5bkx44lrrw5pt@linutronix.de/
Link: https://lkml.kernel.org/r/20211028143327.hfbxjze7palrpfgp@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 0ad9500e16 ("slub: prefetch next freelist pointer in
slab_alloc()") introduced prefetch_freepointer() because when other
cpu(s) freed objects into a page that current cpu owns, the freelist
link is hot on cpu(s) which freed objects and possibly very cold on
current cpu.
But if freelist link chain is hot on cpu(s) which freed objects, it's
better to invalidate that chain because they're not going to access
again within a short time.
So use prefetchw instead of prefetch. On supported architectures like
x86 and arm, it invalidates other copied instances of a cache line when
prefetching it.
Before:
Time: 91.677
Performance counter stats for 'hackbench -g 100 -l 10000':
1462938.07 msec cpu-clock # 15.908 CPUs utilized
18072550 context-switches # 12.354 K/sec
1018814 cpu-migrations # 696.416 /sec
104558 page-faults # 71.471 /sec
1580035699271 cycles # 1.080 GHz (54.51%)
2003670016013 instructions # 1.27 insn per cycle (54.31%)
5702204863 branch-misses (54.28%)
643368500985 cache-references # 439.778 M/sec (54.26%)
18475582235 cache-misses # 2.872 % of all cache refs (54.28%)
642206796636 L1-dcache-loads # 438.984 M/sec (46.87%)
18215813147 L1-dcache-load-misses # 2.84% of all L1-dcache accesses (46.83%)
653842996501 dTLB-loads # 446.938 M/sec (46.63%)
3227179675 dTLB-load-misses # 0.49% of all dTLB cache accesses (46.85%)
537531951350 iTLB-loads # 367.433 M/sec (54.33%)
114750630 iTLB-load-misses # 0.02% of all iTLB cache accesses (54.37%)
630135543177 L1-icache-loads # 430.733 M/sec (46.80%)
22923237620 L1-icache-load-misses # 3.64% of all L1-icache accesses (46.76%)
91.964452802 seconds time elapsed
43.416742000 seconds user
1422.441123000 seconds sys
After:
Time: 90.220
Performance counter stats for 'hackbench -g 100 -l 10000':
1437418.48 msec cpu-clock # 15.880 CPUs utilized
17694068 context-switches # 12.310 K/sec
958257 cpu-migrations # 666.651 /sec
100604 page-faults # 69.989 /sec
1583259429428 cycles # 1.101 GHz (54.57%)
2004002484935 instructions # 1.27 insn per cycle (54.37%)
5594202389 branch-misses (54.36%)
643113574524 cache-references # 447.409 M/sec (54.39%)
18233791870 cache-misses # 2.835 % of all cache refs (54.37%)
640205852062 L1-dcache-loads # 445.386 M/sec (46.75%)
17968160377 L1-dcache-load-misses # 2.81% of all L1-dcache accesses (46.79%)
651747432274 dTLB-loads # 453.415 M/sec (46.59%)
3127124271 dTLB-load-misses # 0.48% of all dTLB cache accesses (46.75%)
535395273064 iTLB-loads # 372.470 M/sec (54.38%)
113500056 iTLB-load-misses # 0.02% of all iTLB cache accesses (54.35%)
628871845924 L1-icache-loads # 437.501 M/sec (46.80%)
22585641203 L1-icache-load-misses # 3.59% of all L1-icache accesses (46.79%)
90.514819303 seconds time elapsed
43.877656000 seconds user
1397.176001000 seconds sys
Link: https://lkml.org/lkml/2021/10/8/598=20
Link: https://lkml.kernel.org/r/20211011144331.70084-1-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The defaults are determined based on object size and can go up to 30 for
objects smaller than 256 bytes. Before the previous patch changed the
accounting, this could have made cpu partial list contain up to 30
pages. After that patch, only up to 2 pages with default allocation
order.
Very short lists limit the usefulness of the whole concept of cpu
partial lists, so this patch aims at a more reasonable default under the
new accounting. The defaults are quadrupled, except for object size >=
PAGE_SIZE where it's doubled. This makes the lists grow up to 10 pages
in practice.
A quick test of booting a kernel under virtme with 4GB RAM and 8 vcpus
shows the following slab memory usage after boot:
Before previous patch (using page->pobjects):
Slab: 36732 kB
SReclaimable: 14836 kB
SUnreclaim: 21896 kB
After previous patch (using page->pages):
Slab: 34720 kB
SReclaimable: 13716 kB
SUnreclaim: 21004 kB
After this patch (using page->pages, higher defaults):
Slab: 35252 kB
SReclaimable: 13944 kB
SUnreclaim: 21308 kB
In the same setup, I also ran 5 times:
hackbench -l 16000 -g 16
Differences in time were in the noise, we can compare slub stats as
given by slabinfo -r skbuff_head_cache (the other cache heavily used by
hackbench, kmalloc-cg-512 looks similar). Negligible stats left out for
brevity.
Before previous patch (using page->pobjects):
Objects: 1408, Memory Total: 401408 Used : 304128
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 469952498 5946606 91 1
Slowpath 42053573 506059465 8 98
Page Alloc 41093 41044 0 0
Add partial 18 21229327 0 4
Remove partial 20039522 36051 3 0
Cpu partial list 4686640 24767229 0 4
RemoteObj/SlabFrozen 16 124027841 0 24
Total 512006071 512006071
Flushes 18
Slab Deactivation Occurrences %
-------------------------------------------------
Slab empty 4993 0%
Deactivation bypass 24767229 99%
Refilled from foreign frees 21972674 88%
After previous patch (using page->pages):
Objects: 480, Memory Total: 131072 Used : 103680
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 473016294 5405653 92 1
Slowpath 38989777 506600418 7 98
Page Alloc 32717 32701 0 0
Add partial 3 22749164 0 4
Remove partial 11371127 32474 2 0
Cpu partial list 11686226 23090059 2 4
RemoteObj/SlabFrozen 2 67541803 0 13
Total 512006071 512006071
Flushes 3
Slab Deactivation Occurrences %
-------------------------------------------------
Slab empty 227 0%
Deactivation bypass 23090059 99%
Refilled from foreign frees 27585695 119%
After this patch (using page->pages, higher defaults):
Objects: 896, Memory Total: 229376 Used : 193536
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 473799295 4980278 92 0
Slowpath 38206776 507025793 7 99
Page Alloc 32295 32267 0 0
Add partial 11 23291143 0 4
Remove partial 5815764 31278 1 0
Cpu partial list 18119280 23967320 3 4
RemoteObj/SlabFrozen 10 76974794 0 15
Total 512006071 512006071
Flushes 11
Slab Deactivation Occurrences %
-------------------------------------------------
Slab empty 989 0%
Deactivation bypass 23967320 99%
Refilled from foreign frees 32358473 135%
As expected, memory usage dropped significantly with change of
accounting, increasing the defaults increased it, but not as much. The
number of page allocation/frees dropped significantly with the new
accounting, but didn't increase with the higher defaults.
Interestingly, the number of fasthpath allocations increased, as well as
allocations from the cpu partial list, even though it's shorter.
Link: https://lkml.kernel.org/r/20211012134651.11258-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With CONFIG_SLUB_CPU_PARTIAL enabled, SLUB keeps a percpu list of
partial slabs that can be promoted to cpu slab when the previous one is
depleted, without accessing the shared partial list. A slab can be
added to this list by 1) refill of an empty list from get_partial_node()
- once we really have to access the shared partial list, we acquire
multiple slabs to amortize the cost of locking, and 2) first free to a
previously full slab - instead of putting the slab on a shared partial
list, we can more cheaply freeze it and put it on the per-cpu list.
To control how large a percpu partial list can grow for a kmem cache,
set_cpu_partial() calculates a target number of free objects on each
cpu's percpu partial list, and this can be also set by the sysfs file
cpu_partial.
However, the tracking of actual number of objects is imprecise, in order
to limit overhead from cpu X freeing an objects to a slab on percpu
partial list of cpu Y. Basically, the percpu partial slabs form a
single linked list, and when we add a new slab to the list with current
head "oldpage", we set in the struct page of the slab we're adding:
page->pages = oldpage->pages + 1; // this is precise
page->pobjects = oldpage->pobjects + (page->objects - page->inuse);
page->next = oldpage;
Thus the real number of free objects in the slab (objects - inuse) is
only determined at the moment of adding the slab to the percpu partial
list, and further freeing doesn't update the pobjects counter nor
propagate it to the current list head. As Jann reports [1], this can
easily lead to large inaccuracies, where the target number of objects
(up to 30 by default) can translate to the same number of (empty) slab
pages on the list. In case 2) above, we put a slab with 1 free object
on the list, thus only increase page->pobjects by 1, even if there are
subsequent frees on the same slab. Jann has noticed this in practice
and so did we [2] when investigating significant increase of kmemcg
usage after switching from SLAB to SLUB.
While this is no longer a problem in kmemcg context thanks to the
accounting rewrite in 5.9, the memory waste is still not ideal and it's
questionable whether it makes sense to perform free object count based
control when object counts can easily become so much inaccurate. So
this patch converts the accounting to be based on number of pages only
(which is precise) and removes the page->pobjects field completely.
This is also ultimately simpler.
To retain the existing set_cpu_partial() heuristic, first calculate the
target number of objects as previously, but then convert it to target
number of pages by assuming the pages will be half-filled on average.
This assumption might obviously also be inaccurate in practice, but
cannot degrade to actual number of pages being equal to the target
number of objects.
We could also skip the intermediate step with target number of objects
and rewrite the heuristic in terms of pages. However we still have the
sysfs file cpu_partial which uses number of objects and could break
existing users if it suddenly becomes number of pages, so this patch
doesn't do that.
In practice, after this patch the heuristics limit the size of percpu
partial list up to 2 pages. In case of a reported regression (which
would mean some workload has benefited from the previous imprecise
object based counting), we can tune the heuristics to get a better
compromise within the new scheme, while still avoid the unexpectedly
long percpu partial lists.
[1] https://lore.kernel.org/linux-mm/CAG48ez2Qx5K1Cab-m8BdSibp6wLTip6ro4=-umR7BLsEgjEYzA@mail.gmail.com/
[2] https://lore.kernel.org/all/2f0f46e8-2535-410a-1859-e9cfa4e57c18@suse.cz/
==========
Evaluation
==========
Mel was kind enough to run v1 through mmtests machinery for netperf
(localhost) and hackbench and, for most significant results see below.
So there are some apparent regressions, especially with hackbench, which
I think ultimately boils down to having shorter percpu partial lists on
average and some benchmarks benefiting from longer ones. Monitoring
slab usage also indicated less memory usage by slab. Based on that, the
following patch will bump the defaults to allow longer percpu partial
lists than after this patch.
However the goal is certainly not such that we would limit the percpu
partial lists to 30 pages just because previously a specific alloc/free
pattern could lead to the limit of 30 objects translate to a limit to 30
pages - that would make little sense. This is a correctness patch, and
if a workload benefits from larger lists, the sysfs tuning knobs are
still there to allow that.
Netperf
2-socket Intel(R) Xeon(R) Gold 5218R CPU @ 2.10GHz (20 cores, 40 threads per socket), 384GB RAM
TCP-RR:
hmean before 127045.79 after 121092.94 (-4.69%, worse)
stddev before 2634.37 after 1254.08
UDP-RR:
hmean before 166985.45 after 160668.94 ( -3.78%, worse)
stddev before 4059.69 after 1943.63
2-socket Intel(R) Xeon(R) CPU E5-2698 v4 @ 2.20GHz (20 cores, 40 threads per socket), 512GB RAM
TCP-RR:
hmean before 84173.25 after 76914.72 ( -8.62%, worse)
UDP-RR:
hmean before 93571.12 after 96428.69 ( 3.05%, better)
stddev before 23118.54 after 16828.14
2-socket Intel(R) Xeon(R) CPU E5-2670 v3 @ 2.30GHz (12 cores, 24 threads per socket), 64GB RAM
TCP-RR:
hmean before 49984.92 after 48922.27 ( -2.13%, worse)
stddev before 6248.15 after 4740.51
UDP-RR:
hmean before 61854.31 after 68761.81 ( 11.17%, better)
stddev before 4093.54 after 5898.91
other machines - within 2%
Hackbench
(results before and after the patch, negative % means worse)
2-socket AMD EPYC 7713 (64 cores, 128 threads per core), 256GB RAM
hackbench-process-sockets
Amean 1 0.5380 0.5583 ( -3.78%)
Amean 4 0.7510 0.8150 ( -8.52%)
Amean 7 0.7930 0.9533 ( -20.22%)
Amean 12 0.7853 1.1313 ( -44.06%)
Amean 21 1.1520 1.4993 ( -30.15%)
Amean 30 1.6223 1.9237 ( -18.57%)
Amean 48 2.6767 2.9903 ( -11.72%)
Amean 79 4.0257 5.1150 ( -27.06%)
Amean 110 5.5193 7.4720 ( -35.38%)
Amean 141 7.2207 9.9840 ( -38.27%)
Amean 172 8.4770 12.1963 ( -43.88%)
Amean 203 9.6473 14.3137 ( -48.37%)
Amean 234 11.3960 18.7917 ( -64.90%)
Amean 265 13.9627 22.4607 ( -60.86%)
Amean 296 14.9163 26.0483 ( -74.63%)
hackbench-thread-sockets
Amean 1 0.5597 0.5877 ( -5.00%)
Amean 4 0.7913 0.8960 ( -13.23%)
Amean 7 0.8190 1.0017 ( -22.30%)
Amean 12 0.9560 1.1727 ( -22.66%)
Amean 21 1.7587 1.5660 ( 10.96%)
Amean 30 2.4477 1.9807 ( 19.08%)
Amean 48 3.4573 3.0630 ( 11.41%)
Amean 79 4.7903 5.1733 ( -8.00%)
Amean 110 6.1370 7.4220 ( -20.94%)
Amean 141 7.5777 9.2617 ( -22.22%)
Amean 172 9.2280 11.0907 ( -20.18%)
Amean 203 10.2793 13.3470 ( -29.84%)
Amean 234 11.2410 17.1070 ( -52.18%)
Amean 265 12.5970 23.3323 ( -85.22%)
Amean 296 17.1540 24.2857 ( -41.57%)
2-socket Intel(R) Xeon(R) Gold 5218R CPU @ 2.10GHz (20 cores, 40 threads
per socket), 384GB RAM
hackbench-process-sockets
Amean 1 0.5760 0.4793 ( 16.78%)
Amean 4 0.9430 0.9707 ( -2.93%)
Amean 7 1.5517 1.8843 ( -21.44%)
Amean 12 2.4903 2.7267 ( -9.49%)
Amean 21 3.9560 4.2877 ( -8.38%)
Amean 30 5.4613 5.8343 ( -6.83%)
Amean 48 8.5337 9.2937 ( -8.91%)
Amean 79 14.0670 15.2630 ( -8.50%)
Amean 110 19.2253 21.2467 ( -10.51%)
Amean 141 23.7557 25.8550 ( -8.84%)
Amean 172 28.4407 29.7603 ( -4.64%)
Amean 203 33.3407 33.9927 ( -1.96%)
Amean 234 38.3633 39.1150 ( -1.96%)
Amean 265 43.4420 43.8470 ( -0.93%)
Amean 296 48.3680 48.9300 ( -1.16%)
hackbench-thread-sockets
Amean 1 0.6080 0.6493 ( -6.80%)
Amean 4 1.0000 1.0513 ( -5.13%)
Amean 7 1.6607 2.0260 ( -22.00%)
Amean 12 2.7637 2.9273 ( -5.92%)
Amean 21 5.0613 4.5153 ( 10.79%)
Amean 30 6.3340 6.1140 ( 3.47%)
Amean 48 9.0567 9.5577 ( -5.53%)
Amean 79 14.5657 15.7983 ( -8.46%)
Amean 110 19.6213 21.6333 ( -10.25%)
Amean 141 24.1563 26.2697 ( -8.75%)
Amean 172 28.9687 30.2187 ( -4.32%)
Amean 203 33.9763 34.6970 ( -2.12%)
Amean 234 38.8647 39.3207 ( -1.17%)
Amean 265 44.0813 44.1507 ( -0.16%)
Amean 296 49.2040 49.4330 ( -0.47%)
2-socket Intel(R) Xeon(R) CPU E5-2698 v4 @ 2.20GHz (20 cores, 40 threads
per socket), 512GB RAM
hackbench-process-sockets
Amean 1 0.5027 0.5017 ( 0.20%)
Amean 4 1.1053 1.2033 ( -8.87%)
Amean 7 1.8760 2.1820 ( -16.31%)
Amean 12 2.9053 3.1810 ( -9.49%)
Amean 21 4.6777 4.9920 ( -6.72%)
Amean 30 6.5180 6.7827 ( -4.06%)
Amean 48 10.0710 10.5227 ( -4.48%)
Amean 79 16.4250 17.5053 ( -6.58%)
Amean 110 22.6203 24.4617 ( -8.14%)
Amean 141 28.0967 31.0363 ( -10.46%)
Amean 172 34.4030 36.9233 ( -7.33%)
Amean 203 40.5933 43.0850 ( -6.14%)
Amean 234 46.6477 48.7220 ( -4.45%)
Amean 265 53.0530 53.9597 ( -1.71%)
Amean 296 59.2760 59.9213 ( -1.09%)
hackbench-thread-sockets
Amean 1 0.5363 0.5330 ( 0.62%)
Amean 4 1.1647 1.2157 ( -4.38%)
Amean 7 1.9237 2.2833 ( -18.70%)
Amean 12 2.9943 3.3110 ( -10.58%)
Amean 21 4.9987 5.1880 ( -3.79%)
Amean 30 6.7583 7.0043 ( -3.64%)
Amean 48 10.4547 10.8353 ( -3.64%)
Amean 79 16.6707 17.6790 ( -6.05%)
Amean 110 22.8207 24.4403 ( -7.10%)
Amean 141 28.7090 31.0533 ( -8.17%)
Amean 172 34.9387 36.8260 ( -5.40%)
Amean 203 41.1567 43.0450 ( -4.59%)
Amean 234 47.3790 48.5307 ( -2.43%)
Amean 265 53.9543 54.6987 ( -1.38%)
Amean 296 60.0820 60.2163 ( -0.22%)
1-socket Intel(R) Xeon(R) CPU E3-1240 v5 @ 3.50GHz (4 cores, 8 threads),
32 GB RAM
hackbench-process-sockets
Amean 1 1.4760 1.5773 ( -6.87%)
Amean 3 3.9370 4.0910 ( -3.91%)
Amean 5 6.6797 6.9357 ( -3.83%)
Amean 7 9.3367 9.7150 ( -4.05%)
Amean 12 15.7627 16.1400 ( -2.39%)
Amean 18 23.5360 23.6890 ( -0.65%)
Amean 24 31.0663 31.3137 ( -0.80%)
Amean 30 38.7283 39.0037 ( -0.71%)
Amean 32 41.3417 41.6097 ( -0.65%)
hackbench-thread-sockets
Amean 1 1.5250 1.6043 ( -5.20%)
Amean 3 4.0897 4.2603 ( -4.17%)
Amean 5 6.7760 7.0933 ( -4.68%)
Amean 7 9.4817 9.9157 ( -4.58%)
Amean 12 15.9610 16.3937 ( -2.71%)
Amean 18 23.9543 24.3417 ( -1.62%)
Amean 24 31.4400 31.7217 ( -0.90%)
Amean 30 39.2457 39.5467 ( -0.77%)
Amean 32 41.8267 42.1230 ( -0.71%)
2-socket Intel(R) Xeon(R) CPU E5-2670 v3 @ 2.30GHz (12 cores, 24 threads
per socket), 64GB RAM
hackbench-process-sockets
Amean 1 1.0347 1.0880 ( -5.15%)
Amean 4 1.7267 1.8527 ( -7.30%)
Amean 7 2.6707 2.8110 ( -5.25%)
Amean 12 4.1617 4.3383 ( -4.25%)
Amean 21 7.0070 7.2600 ( -3.61%)
Amean 30 9.9187 10.2397 ( -3.24%)
Amean 48 15.6710 16.3923 ( -4.60%)
Amean 79 24.7743 26.1247 ( -5.45%)
Amean 110 34.3000 35.9307 ( -4.75%)
Amean 141 44.2043 44.8010 ( -1.35%)
Amean 172 54.2430 54.7260 ( -0.89%)
Amean 192 60.6557 60.9777 ( -0.53%)
hackbench-thread-sockets
Amean 1 1.0610 1.1353 ( -7.01%)
Amean 4 1.7543 1.9140 ( -9.10%)
Amean 7 2.7840 2.9573 ( -6.23%)
Amean 12 4.3813 4.4937 ( -2.56%)
Amean 21 7.3460 7.5350 ( -2.57%)
Amean 30 10.2313 10.5190 ( -2.81%)
Amean 48 15.9700 16.5940 ( -3.91%)
Amean 79 25.3973 26.6637 ( -4.99%)
Amean 110 35.1087 36.4797 ( -3.91%)
Amean 141 45.8220 46.3053 ( -1.05%)
Amean 172 55.4917 55.7320 ( -0.43%)
Amean 192 62.7490 62.5410 ( 0.33%)
Link: https://lkml.kernel.org/r/20211012134651.11258-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Jann Horn <jannh@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After commit f227f0faf6 ("slub: fix unreclaimable slab stat for bulk
free"), the check for free nonslab page is replaced by VM_BUG_ON_PAGE,
which only check with CONFIG_DEBUG_VM enabled, but this config may
impact performance, so it only for debug.
Commit 0937502af7 ("slub: Add check for kfree() of non slab objects.")
add the ability, which should be needed in any configs to catch the
invalid free, they even could be potential issue, eg, memory corruption,
use after free and double free, so replace VM_BUG_ON_PAGE to
WARN_ON_ONCE, add object address printing to help use to debug the
issue.
Link: https://lkml.kernel.org/r/20210930070214.61499-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rienjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These lines are useless, so remove them.
Link: https://lkml.kernel.org/r/20210930034845.2539-1-shi_lei@massclouds.com
Fixes: 10befea91b ("mm: memcg/slab: use a single set of kmem_caches for all allocations")
Signed-off-by: Shi Lei <shi_lei@massclouds.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull per signal_struct coredumps from Eric Biederman:
"Current coredumps are mixed up with the exit code, the signal handling
code, and the ptrace code making coredumps much more complicated than
necessary and difficult to follow.
This series of changes starts with ptrace_stop and cleans it up,
making it easier to follow what is happening in ptrace_stop. Then
cleans up the exec interactions with coredumps. Then cleans up the
coredump interactions with exit. Finally the coredump interactions
with the signal handling code is cleaned up.
The first and last changes are bug fixes for minor bugs.
I believe the fact that vfork followed by execve can kill the process
the called vfork if exec fails is sufficient justification to change
the userspace visible behavior.
In previous discussions some of these changes were organized
differently and individually appeared to make the code base worse. As
currently written I believe they all stand on their own as cleanups
and bug fixes.
Which means that even if the worst should happen and the last change
needs to be reverted for some unimaginable reason, the code base will
still be improved.
If the worst does not happen there are a more cleanups that can be
made. Signals that generate coredumps can easily become eligible for
short circuit delivery in complete_signal. The entire rendezvous for
generating a coredump can move into get_signal. The function
force_sig_info_to_task be written in a way that does not modify the
signal handling state of the target task (because coredumps are
eligible for short circuit delivery). Many of these future cleanups
can be done another way but nothing so cleanly as if coredumps become
per signal_struct"
* 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
coredump: Limit coredumps to a single thread group
coredump: Don't perform any cleanups before dumping core
exit: Factor coredump_exit_mm out of exit_mm
exec: Check for a pending fatal signal instead of core_state
ptrace: Remove the unnecessary arguments from arch_ptrace_stop
signal: Remove the bogus sigkill_pending in ptrace_stop
Move shmem_exchange and make it available to other callers.
Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20211028094724.59043-2-lmb@cloudflare.com
core:
- improve dma_fence, lease and resv documentation
- shmem-helpers: allocate WC pages on x86, use vmf_insert_pin
- sched fixes/improvements
- allow empty drm leases
- add dma resv iterator
- add more DP 2.0 headers
- DP MST helper improvements for DP2.0
dma-buf:
- avoid warnings, remove fence trace macros
bridge:
- new helper to get rid of panels
- probe improvements for it66121
- enable DSI EOTP for anx7625
fbdev:
- efifb: release runtime PM on destroy
ttm:
- kerneldoc switch
- helper to clear all DMA mappings
- pool shrinker optimizaton
- remove ttm_tt_destroy_common
- update ttm_move_memcpy for async use
panel:
- add new panel-edp driver
amdgpu:
- Initial DP 2.0 support
- Initial USB4 DP tunnelling support
- Aldebaran MCE support
- Modifier support for DCC image stores for GFX 10.3
- Display rework for better FP code handling
- Yellow Carp/Cyan Skillfish updates
- Cyan Skillfish display support
- convert vega/navi to IP discovery asic enumeration
- validate IP discovery table
- RAS improvements
- Lots of fixes
i915:
- DG1 PCI IDs + LMEM discovery/placement
- DG1 GuC submission by default
- ADL-S PCI IDs updated + enabled by default
- ADL-P (XE_LPD) fixed and updates
- DG2 display fixes
- PXP protected object support for Gen12 integrated
- expose multi-LRC submission interface for GuC
- export logical engine instance to user
- Disable engine bonding on Gen12+
- PSR cleanup
- PSR2 selective fetch by default
- DP 2.0 prep work
- VESA vendor block + MSO use of it
- FBC refactor
- try again to fix fast-narrow vs slow-wide eDP training
- use THP when IOMMU enabled
- LMEM backup/restore for suspend/resume
- locking simplification
- GuC major reworking
- async flip VT-D workaround changes
- DP link training improvements
- misc display refactorings
bochs:
- new PCI ID
rcar-du:
- Non-contiguious buffer import support for rcar-du
- r8a779a0 support prep
omapdrm:
- COMPILE_TEST fixes
sti:
- COMPILE_TEST fixes
msm:
- fence ordering improvements
- eDP support in DP sub-driver
- dpu irq handling cleanup
- CRC support for making igt happy
- NO_CONNECTOR bridge support
- dsi: 14nm phy support for msm8953
- mdp5: msm8x53, sdm450, sdm632 support
stm:
- layer alpha + zpo support
v3d:
- fix Vulkan CTS failure
- support multiple sync objects
gud:
- add R8/RGB332/RGB888 pixel formats
vc4:
- convert to new bridge helpers
vgem:
- use shmem helpers
virtio:
- support mapping exported vram
zte:
- remove obsolete driver
rockchip:
- use bridge attach no connector for LVDS/RGB
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Merge tag 'drm-next-2021-11-03' of git://anongit.freedesktop.org/drm/drm
Pull drm updates from Dave Airlie:
"Summary below. i915 starts to add support for DG2 GPUs, enables DG1
and ADL-S support by default, lots of work to enable DisplayPort 2.0
across drivers. Lots of documentation updates and fixes across the
board.
core:
- improve dma_fence, lease and resv documentation
- shmem-helpers: allocate WC pages on x86, use vmf_insert_pin
- sched fixes/improvements
- allow empty drm leases
- add dma resv iterator
- add more DP 2.0 headers
- DP MST helper improvements for DP2.0
dma-buf:
- avoid warnings, remove fence trace macros
bridge:
- new helper to get rid of panels
- probe improvements for it66121
- enable DSI EOTP for anx7625
fbdev:
- efifb: release runtime PM on destroy
ttm:
- kerneldoc switch
- helper to clear all DMA mappings
- pool shrinker optimizaton
- remove ttm_tt_destroy_common
- update ttm_move_memcpy for async use
panel:
- add new panel-edp driver
amdgpu:
- Initial DP 2.0 support
- Initial USB4 DP tunnelling support
- Aldebaran MCE support
- Modifier support for DCC image stores for GFX 10.3
- Display rework for better FP code handling
- Yellow Carp/Cyan Skillfish updates
- Cyan Skillfish display support
- convert vega/navi to IP discovery asic enumeration
- validate IP discovery table
- RAS improvements
- Lots of fixes
i915:
- DG1 PCI IDs + LMEM discovery/placement
- DG1 GuC submission by default
- ADL-S PCI IDs updated + enabled by default
- ADL-P (XE_LPD) fixed and updates
- DG2 display fixes
- PXP protected object support for Gen12 integrated
- expose multi-LRC submission interface for GuC
- export logical engine instance to user
- Disable engine bonding on Gen12+
- PSR cleanup
- PSR2 selective fetch by default
- DP 2.0 prep work
- VESA vendor block + MSO use of it
- FBC refactor
- try again to fix fast-narrow vs slow-wide eDP training
- use THP when IOMMU enabled
- LMEM backup/restore for suspend/resume
- locking simplification
- GuC major reworking
- async flip VT-D workaround changes
- DP link training improvements
- misc display refactorings
bochs:
- new PCI ID
rcar-du:
- Non-contiguious buffer import support for rcar-du
- r8a779a0 support prep
omapdrm:
- COMPILE_TEST fixes
sti:
- COMPILE_TEST fixes
msm:
- fence ordering improvements
- eDP support in DP sub-driver
- dpu irq handling cleanup
- CRC support for making igt happy
- NO_CONNECTOR bridge support
- dsi: 14nm phy support for msm8953
- mdp5: msm8x53, sdm450, sdm632 support
stm:
- layer alpha + zpo support
v3d:
- fix Vulkan CTS failure
- support multiple sync objects
gud:
- add R8/RGB332/RGB888 pixel formats
vc4:
- convert to new bridge helpers
vgem:
- use shmem helpers
virtio:
- support mapping exported vram
zte:
- remove obsolete driver
rockchip:
- use bridge attach no connector for LVDS/RGB"
* tag 'drm-next-2021-11-03' of git://anongit.freedesktop.org/drm/drm: (1259 commits)
drm/amdgpu/gmc6: fix DMA mask from 44 to 40 bits
drm/amd/display: MST support for DPIA
drm/amdgpu: Fix even more out of bound writes from debugfs
drm/amdgpu/discovery: add SDMA IP instance info for soc15 parts
drm/amdgpu/discovery: add UVD/VCN IP instance info for soc15 parts
drm/amdgpu/UAPI: rearrange header to better align related items
drm/amd/display: Enable dpia in dmub only for DCN31 B0
drm/amd/display: Fix USB4 hot plug crash issue
drm/amd/display: Fix deadlock when falling back to v2 from v3
drm/amd/display: Fallback to clocks which meet requested voltage on DCN31
drm/amd/display: move FPU associated DCN301 code to DML folder
drm/amd/display: fix link training regression for 1 or 2 lane
drm/amd/display: add two lane settings training options
drm/amd/display: decouple hw_lane_settings from dpcd_lane_settings
drm/amd/display: implement decide lane settings
drm/amd/display: adopt DP2.0 LT SCR revision 8
drm/amd/display: FEC configuration for dpia links in MST mode
drm/amd/display: FEC configuration for dpia links
drm/amd/display: Add workaround flag for EDID read on certain docks
drm/amd/display: Set phy_mux_sel bit in dmub scratch register
...
Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock. In the most basic scenario, that buffer will not be
resident and it will be mapped to the same file. Accessing the buffer
will trigger a page fault, and gfs2 will deadlock trying to take the
same inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled.
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Merge tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
Pull gfs2 mmap + page fault deadlocks fixes from Andreas Gruenbacher:
"Functions gfs2_file_read_iter and gfs2_file_write_iter are both
accessing the user buffer to write to or read from while holding the
inode glock.
In the most basic deadlock scenario, that buffer will not be resident
and it will be mapped to the same file. Accessing the buffer will
trigger a page fault, and gfs2 will deadlock trying to take the same
inode glock again while trying to handle that fault.
Fix that and similar, more complex scenarios by disabling page faults
while accessing user buffers. To make this work, introduce a small
amount of new infrastructure and fix some bugs that didn't trigger so
far, with page faults enabled"
* tag 'gfs2-v5.15-rc5-mmap-fault' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: Fix mmap + page fault deadlocks for direct I/O
iov_iter: Introduce nofault flag to disable page faults
gup: Introduce FOLL_NOFAULT flag to disable page faults
iomap: Add done_before argument to iomap_dio_rw
iomap: Support partial direct I/O on user copy failures
iomap: Fix iomap_dio_rw return value for user copies
gfs2: Fix mmap + page fault deadlocks for buffered I/O
gfs2: Eliminate ip->i_gh
gfs2: Move the inode glock locking to gfs2_file_buffered_write
gfs2: Introduce flag for glock holder auto-demotion
gfs2: Clean up function may_grant
gfs2: Add wrapper for iomap_file_buffered_write
iov_iter: Introduce fault_in_iov_iter_writeable
iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable
gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable}
powerpc/kvm: Fix kvm_use_magic_page
iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value
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Merge tag 'printk-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Extend %pGp print format to print hex value of the page flags
- Use kvmalloc instead of kmalloc to allocate devkmsg buffers
- Misc cleanup and warning fixes
* tag 'printk-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
vsprintf: Update %pGp documentation about that it prints hex value
lib/vsprintf.c: Amend static asserts for format specifier flags
vsprintf: Make %pGp print the hex value
test_printf: Append strings more efficiently
test_printf: Remove custom appending of '|'
test_printf: Remove separate page_flags variable
test_printf: Make pft array const
ia64: don't do IA64_CMPXCHG_DEBUG without CONFIG_PRINTK
printk: use gnu_printf format attribute for printk_sprint()
printk: avoid -Wsometimes-uninitialized warning
printk: use kvmalloc instead of kmalloc for devkmsg_user
- Support for the Arm8.6 timer extensions, including a self-synchronising
view of the system registers to elide some expensive ISB instructions.
- Exception table cleanup and rework so that the fixup handlers appear
correctly in backtraces.
- A handful of miscellaneous changes, the main one being selection of
CONFIG_HAVE_POSIX_CPU_TIMERS_TASK_WORK.
- More mm and pgtable cleanups.
- KASAN support for "asymmetric" MTE, where tag faults are reported
synchronously for loads (via an exception) and asynchronously for
stores (via a register).
- Support for leaving the MMU enabled during kexec relocation, which
significantly speeds up the operation.
- Minor improvements to our perf PMU drivers.
- Improvements to the compat vDSO build system, particularly when
building with LLVM=1.
- Preparatory work for handling some Coresight TRBE tracing errata.
- Cleanup and refactoring of the SVE code to pave the way for SME
support in future.
- Ensure SCS pages are unpoisoned immediately prior to freeing them
when KASAN is enabled for the vmalloc area.
- Try moving to the generic pfn_valid() implementation again now that
the DMA mapping issue from last time has been resolved.
- Numerous improvements and additions to our FPSIMD and SVE selftests.
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"There's the usual summary below, but the highlights are support for
the Armv8.6 timer extensions, KASAN support for asymmetric MTE, the
ability to kexec() with the MMU enabled and a second attempt at
switching to the generic pfn_valid() implementation.
Summary:
- Support for the Arm8.6 timer extensions, including a
self-synchronising view of the system registers to elide some
expensive ISB instructions.
- Exception table cleanup and rework so that the fixup handlers
appear correctly in backtraces.
- A handful of miscellaneous changes, the main one being selection of
CONFIG_HAVE_POSIX_CPU_TIMERS_TASK_WORK.
- More mm and pgtable cleanups.
- KASAN support for "asymmetric" MTE, where tag faults are reported
synchronously for loads (via an exception) and asynchronously for
stores (via a register).
- Support for leaving the MMU enabled during kexec relocation, which
significantly speeds up the operation.
- Minor improvements to our perf PMU drivers.
- Improvements to the compat vDSO build system, particularly when
building with LLVM=1.
- Preparatory work for handling some Coresight TRBE tracing errata.
- Cleanup and refactoring of the SVE code to pave the way for SME
support in future.
- Ensure SCS pages are unpoisoned immediately prior to freeing them
when KASAN is enabled for the vmalloc area.
- Try moving to the generic pfn_valid() implementation again now that
the DMA mapping issue from last time has been resolved.
- Numerous improvements and additions to our FPSIMD and SVE
selftests"
[ armv8.6 timer updates were in a shared branch and already came in
through -tip in the timer pull - Linus ]
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (85 commits)
arm64: Select POSIX_CPU_TIMERS_TASK_WORK
arm64: Document boot requirements for FEAT_SME_FA64
arm64/sve: Fix warnings when SVE is disabled
arm64/sve: Add stub for sve_max_virtualisable_vl()
arm64: errata: Add detection for TRBE write to out-of-range
arm64: errata: Add workaround for TSB flush failures
arm64: errata: Add detection for TRBE overwrite in FILL mode
arm64: Add Neoverse-N2, Cortex-A710 CPU part definition
selftests: arm64: Factor out utility functions for assembly FP tests
arm64: vmlinux.lds.S: remove `.fixup` section
arm64: extable: add load_unaligned_zeropad() handler
arm64: extable: add a dedicated uaccess handler
arm64: extable: add `type` and `data` fields
arm64: extable: use `ex` for `exception_table_entry`
arm64: extable: make fixup_exception() return bool
arm64: extable: consolidate definitions
arm64: gpr-num: support W registers
arm64: factor out GPR numbering helpers
arm64: kvm: use kvm_exception_table_entry
arm64: lib: __arch_copy_to_user(): fold fixups into body
...
- Move futex code into kernel/futex/ and split up the kitchen sink into
seperate files to make integration of sys_futex_waitv() simpler.
- Add a new sys_futex_waitv() syscall which allows to wait on multiple
futexes. The main use case is emulating Windows' WaitForMultipleObjects
which allows Wine to improve the performance of Windows Games. Also
native Linux games can benefit from this interface as this is a common
wait pattern for this kind of applications.
- Add context to ww_mutex_trylock() to provide a path for i915 to rework
their eviction code step by step without making lockdep upset until the
final steps of rework are completed. It's also useful for regulator and
TTM to avoid dropping locks in the non contended path.
- Lockdep and might_sleep() cleanups and improvements
- A few improvements for the RT substitutions.
- The usual small improvements and cleanups.
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Merge tag 'locking-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Thomas Gleixner:
- Move futex code into kernel/futex/ and split up the kitchen sink into
seperate files to make integration of sys_futex_waitv() simpler.
- Add a new sys_futex_waitv() syscall which allows to wait on multiple
futexes.
The main use case is emulating Windows' WaitForMultipleObjects which
allows Wine to improve the performance of Windows Games. Also native
Linux games can benefit from this interface as this is a common wait
pattern for this kind of applications.
- Add context to ww_mutex_trylock() to provide a path for i915 to
rework their eviction code step by step without making lockdep upset
until the final steps of rework are completed. It's also useful for
regulator and TTM to avoid dropping locks in the non contended path.
- Lockdep and might_sleep() cleanups and improvements
- A few improvements for the RT substitutions.
- The usual small improvements and cleanups.
* tag 'locking-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
locking: Remove spin_lock_flags() etc
locking/rwsem: Fix comments about reader optimistic lock stealing conditions
locking: Remove rcu_read_{,un}lock() for preempt_{dis,en}able()
locking/rwsem: Disable preemption for spinning region
docs: futex: Fix kernel-doc references
futex: Fix PREEMPT_RT build
futex2: Documentation: Document sys_futex_waitv() uAPI
selftests: futex: Test sys_futex_waitv() wouldblock
selftests: futex: Test sys_futex_waitv() timeout
selftests: futex: Add sys_futex_waitv() test
futex,arm: Wire up sys_futex_waitv()
futex,x86: Wire up sys_futex_waitv()
futex: Implement sys_futex_waitv()
futex: Simplify double_lock_hb()
futex: Split out wait/wake
futex: Split out requeue
futex: Rename mark_wake_futex()
futex: Rename: match_futex()
futex: Rename: hb_waiter_{inc,dec,pending}()
futex: Split out PI futex
...
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Merge tag 'for-5.16/block-2021-10-29' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe:
- mq-deadline accounting improvements (Bart)
- blk-wbt timer fix (Andrea)
- Untangle the block layer includes (Christoph)
- Rework the poll support to be bio based, which will enable adding
support for polling for bio based drivers (Christoph)
- Block layer core support for multi-actuator drives (Damien)
- blk-crypto improvements (Eric)
- Batched tag allocation support (me)
- Request completion batching support (me)
- Plugging improvements (me)
- Shared tag set improvements (John)
- Concurrent queue quiesce support (Ming)
- Cache bdev in ->private_data for block devices (Pavel)
- bdev dio improvements (Pavel)
- Block device invalidation and block size improvements (Xie)
- Various cleanups, fixes, and improvements (Christoph, Jackie,
Masahira, Tejun, Yu, Pavel, Zheng, me)
* tag 'for-5.16/block-2021-10-29' of git://git.kernel.dk/linux-block: (174 commits)
blk-mq-debugfs: Show active requests per queue for shared tags
block: improve readability of blk_mq_end_request_batch()
virtio-blk: Use blk_validate_block_size() to validate block size
loop: Use blk_validate_block_size() to validate block size
nbd: Use blk_validate_block_size() to validate block size
block: Add a helper to validate the block size
block: re-flow blk_mq_rq_ctx_init()
block: prefetch request to be initialized
block: pass in blk_mq_tags to blk_mq_rq_ctx_init()
block: add rq_flags to struct blk_mq_alloc_data
block: add async version of bio_set_polled
block: kill DIO_MULTI_BIO
block: kill unused polling bits in __blkdev_direct_IO()
block: avoid extra iter advance with async iocb
block: Add independent access ranges support
blk-mq: don't issue request directly in case that current is to be blocked
sbitmap: silence data race warning
blk-cgroup: synchronize blkg creation against policy deactivation
block: refactor bio_iov_bvec_set()
block: add single bio async direct IO helper
...
Add memory folios, a new type to represent either order-0 pages or
the head page of a compound page. This should be enough infrastructure
to support filesystems converting from pages to folios.
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Merge tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache
Pull memory folios from Matthew Wilcox:
"Add memory folios, a new type to represent either order-0 pages or the
head page of a compound page. This should be enough infrastructure to
support filesystems converting from pages to folios.
The point of all this churn is to allow filesystems and the page cache
to manage memory in larger chunks than PAGE_SIZE. The original plan
was to use compound pages like THP does, but I ran into problems with
some functions expecting only a head page while others expect the
precise page containing a particular byte.
The folio type allows a function to declare that it's expecting only a
head page. Almost incidentally, this allows us to remove various calls
to VM_BUG_ON(PageTail(page)) and compound_head().
This converts just parts of the core MM and the page cache. For 5.17,
we intend to convert various filesystems (XFS and AFS are ready; other
filesystems may make it) and also convert more of the MM and page
cache to folios. For 5.18, multi-page folios should be ready.
The multi-page folios offer some improvement to some workloads. The
80% win is real, but appears to be an artificial benchmark (postgres
startup, which isn't a serious workload). Real workloads (eg building
the kernel, running postgres in a steady state, etc) seem to benefit
between 0-10%. I haven't heard of any performance losses as a result
of this series. Nobody has done any serious performance tuning; I
imagine that tweaking the readahead algorithm could provide some more
interesting wins. There are also other places where we could choose to
create large folios and currently do not, such as writes that are
larger than PAGE_SIZE.
I'd like to thank all my reviewers who've offered review/ack tags:
Christoph Hellwig, David Howells, Jan Kara, Jeff Layton, Johannes
Weiner, Kirill A. Shutemov, Michal Hocko, Mike Rapoport, Vlastimil
Babka, William Kucharski, Yu Zhao and Zi Yan.
I'd also like to thank those who gave feedback I incorporated but
haven't offered up review tags for this part of the series: Nick
Piggin, Mel Gorman, Ming Lei, Darrick Wong, Ted Ts'o, John Hubbard,
Hugh Dickins, and probably a few others who I forget"
* tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache: (90 commits)
mm/writeback: Add folio_write_one
mm/filemap: Add FGP_STABLE
mm/filemap: Add filemap_get_folio
mm/filemap: Convert mapping_get_entry to return a folio
mm/filemap: Add filemap_add_folio()
mm/filemap: Add filemap_alloc_folio
mm/page_alloc: Add folio allocation functions
mm/lru: Add folio_add_lru()
mm/lru: Convert __pagevec_lru_add_fn to take a folio
mm: Add folio_evictable()
mm/workingset: Convert workingset_refault() to take a folio
mm/filemap: Add readahead_folio()
mm/filemap: Add folio_mkwrite_check_truncate()
mm/filemap: Add i_blocks_per_folio()
mm/writeback: Add folio_redirty_for_writepage()
mm/writeback: Add folio_account_redirty()
mm/writeback: Add folio_clear_dirty_for_io()
mm/writeback: Add folio_cancel_dirty()
mm/writeback: Add folio_account_cleaned()
mm/writeback: Add filemap_dirty_folio()
...
Kunit test cases for 'damon_split_regions_of()' expects the number of
regions after calling the function will be same to their request
('nr_sub'). However, the requested number is just an upper-limit,
because the function randomly decides the size of each sub-region.
This fixes the wrong expectation.
Link: https://lkml.kernel.org/r/20211028090628.14948-1-sj@kernel.org
Fixes: 17ccae8bb5 ("mm/damon: add kunit tests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently collapse_file does not explicitly check PG_writeback, instead,
page_has_private and try_to_release_page are used to filter writeback
pages. This does not work for xfs with blocksize equal to or larger
than pagesize, because in such case xfs has no page->private.
This makes collapse_file bail out early for writeback page. Otherwise,
xfs end_page_writeback will panic as follows.
page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32
aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so"
flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)
raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8
raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000
page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u))
page->mem_cgroup:ffff0000c3e9a000
------------[ cut here ]------------
kernel BUG at include/linux/mm.h:1212!
Internal error: Oops - BUG: 0 [#1] SMP
Modules linked in:
BUG: Bad page state in process khugepaged pfn:84ef32
xfs(E)
page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32
libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ...
CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ...
pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
Call trace:
end_page_writeback+0x1c0/0x214
iomap_finish_page_writeback+0x13c/0x204
iomap_finish_ioend+0xe8/0x19c
iomap_writepage_end_bio+0x38/0x50
bio_endio+0x168/0x1ec
blk_update_request+0x278/0x3f0
blk_mq_end_request+0x34/0x15c
virtblk_request_done+0x38/0x74 [virtio_blk]
blk_done_softirq+0xc4/0x110
__do_softirq+0x128/0x38c
__irq_exit_rcu+0x118/0x150
irq_exit+0x1c/0x30
__handle_domain_irq+0x8c/0xf0
gic_handle_irq+0x84/0x108
el1_irq+0xcc/0x180
arch_cpu_idle+0x18/0x40
default_idle_call+0x4c/0x1a0
cpuidle_idle_call+0x168/0x1e0
do_idle+0xb4/0x104
cpu_startup_entry+0x30/0x9c
secondary_start_kernel+0x104/0x180
Code: d4210000 b0006161 910c8021 94013f4d (d4210000)
---[ end trace 4a88c6a074082f8c ]---
Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt
Link: https://lkml.kernel.org/r/20211022023052.33114-1-rongwei.wang@linux.alibaba.com
Fixes: 99cb0dbd47 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Signed-off-by: Xu Yu <xuyu@linux.alibaba.com>
Suggested-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Song Liu <song@kernel.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Dumazet reported a strange numa spreading info in [1], and found
commit 121e6f3258 ("mm/vmalloc: hugepage vmalloc mappings") introduced
this issue [2].
Dig into the difference before and after this patch, page allocation has
some difference:
before:
alloc_large_system_hash
__vmalloc
__vmalloc_node(..., NUMA_NO_NODE, ...)
__vmalloc_node_range
__vmalloc_area_node
alloc_page /* because NUMA_NO_NODE, so choose alloc_page branch */
alloc_pages_current
alloc_page_interleave /* can be proved by print policy mode */
after:
alloc_large_system_hash
__vmalloc
__vmalloc_node(..., NUMA_NO_NODE, ...)
__vmalloc_node_range
__vmalloc_area_node
alloc_pages_node /* choose nid by nuam_mem_id() */
__alloc_pages_node(nid, ....)
So after commit 121e6f3258 ("mm/vmalloc: hugepage vmalloc mappings"),
it will allocate memory in current node instead of interleaving allocate
memory.
Link: https://lore.kernel.org/linux-mm/CANn89iL6AAyWhfxdHO+jaT075iOa3XcYn9k6JJc7JR2XYn6k_Q@mail.gmail.com/ [1]
Link: https://lore.kernel.org/linux-mm/CANn89iLofTR=AK-QOZY87RdUZENCZUT4O6a0hvhu3_EwRMerOg@mail.gmail.com/ [2]
Link: https://lkml.kernel.org/r/20211021080744.874701-2-chenwandun@huawei.com
Fixes: 121e6f3258 ("mm/vmalloc: hugepage vmalloc mappings")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Quoting Dmitry:
"refcount_inc() needs to be done before fd_install(). After
fd_install() finishes, the fd can be used by userspace and
we can have secret data in memory before the refcount_inc().
A straightforward misuse where a user will predict the returned
fd in another thread before the syscall returns and will use it
to store secret data is somewhat dubious because such a user just
shoots themself in the foot.
But a more interesting misuse would be to close the predicted fd
and decrement the refcount before the corresponding refcount_inc,
this way one can briefly drop the refcount to zero while there are
other users of secretmem."
Move fd_install() after refcount_inc().
Link: https://lkml.kernel.org/r/20211021154046.880251-1-keescook@chromium.org
Link: https://lore.kernel.org/lkml/CACT4Y+b1sW6-Hkn8HQYw_SsT7X3tp-CJNh2ci0wG3ZnQz9jjig@mail.gmail.com
Fixes: 9a436f8ff6 ("PM: hibernate: disable when there are active secretmem users")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jordy Zomer <jordy@pwning.systems>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Race between process_mrelease and exit_mmap, where free_pgtables is
called while __oom_reap_task_mm is in progress, leads to kernel crash
during pte_offset_map_lock call. oom-reaper avoids this race by setting
MMF_OOM_VICTIM flag and causing exit_mmap to take and release
mmap_write_lock, blocking it until oom-reaper releases mmap_read_lock.
Reusing MMF_OOM_VICTIM for process_mrelease would be the simplest way to
fix this race, however that would be considered a hack. Fix this race
by elevating mm->mm_users and preventing exit_mmap from executing until
process_mrelease is finished. Patch slightly refactors the code to
adapt for a possible mmget_not_zero failure.
This fix has considerable negative impact on process_mrelease
performance and will likely need later optimization.
Link: https://lkml.kernel.org/r/20211022014658.263508-1-surenb@google.com
Fixes: 884a7e5964 ("mm: introduce process_mrelease system call")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Christian Brauner <christian@brauner.io>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When handling shmem page fault the THP with corrupted subpage could be
PMD mapped if certain conditions are satisfied. But kernel is supposed
to send SIGBUS when trying to map hwpoisoned page.
There are two paths which may do PMD map: fault around and regular
fault.
Before commit f9ce0be71d ("mm: Cleanup faultaround and finish_fault()
codepaths") the thing was even worse in fault around path. The THP
could be PMD mapped as long as the VMA fits regardless what subpage is
accessed and corrupted. After this commit as long as head page is not
corrupted the THP could be PMD mapped.
In the regular fault path the THP could be PMD mapped as long as the
corrupted page is not accessed and the VMA fits.
This loophole could be fixed by iterating every subpage to check if any
of them is hwpoisoned or not, but it is somewhat costly in page fault
path.
So introduce a new page flag called HasHWPoisoned on the first tail
page. It indicates the THP has hwpoisoned subpage(s). It is set if any
subpage of THP is found hwpoisoned by memory failure and after the
refcount is bumped successfully, then cleared when the THP is freed or
split.
The soft offline path doesn't need this since soft offline handler just
marks a subpage hwpoisoned when the subpage is migrated successfully.
But shmem THP didn't get split then migrated at all.
Link: https://lkml.kernel.org/r/20211020210755.23964-3-shy828301@gmail.com
Fixes: 800d8c63b2 ("shmem: add huge pages support")
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When handling THP hwpoison checked if the THP is in allocation or free
stage since hwpoison may mistreat it as hugetlb page. After commit
415c64c145 ("mm/memory-failure: split thp earlier in memory error
handling") the problem has been fixed, so this check is no longer
needed. Remove it. The side effect of the removal is hwpoison may
report unsplit THP instead of unknown error for shmem THP. It seems not
like a big deal.
The following patch "mm: filemap: check if THP has hwpoisoned subpage
for PMD page fault" depends on this, which fixes shmem THP with
hwpoisoned subpage(s) are mapped PMD wrongly. So this patch needs to be
backported to -stable as well.
Link: https://lkml.kernel.org/r/20211020210755.23964-2-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 5c1f4e690e ("mm/vmalloc: switch to bulk allocator in
__vmalloc_area_node()") switched to bulk page allocator for order 0
allocation backing vmalloc. However bulk page allocator does not
support __GFP_ACCOUNT allocations and there are several users of
kvmalloc(__GFP_ACCOUNT).
For now make __GFP_ACCOUNT allocations bypass bulk page allocator. In
future if there is workload that can be significantly improved with the
bulk page allocator with __GFP_ACCCOUNT support, we can revisit the
decision.
Link: https://lkml.kernel.org/r/20211014151607.2171970-1-shakeelb@google.com
Fixes: 5c1f4e690e ("mm/vmalloc: switch to bulk allocator in __vmalloc_area_node()")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Vasily Averin <vvs@virtuozzo.com>
Tested-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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BackMerge tag 'v5.15-rc7' into drm-next
The msm next tree is based on rc3, so let's just backmerge rc7 before pulling it in.
Signed-off-by: Dave Airlie <airlied@redhat.com>
All existing users of %pGp want the hex value as well as the decoded
flag names. This looks awkward (passing the same parameter to printf
twice), so move that functionality into the core. If we want, we
can make that optional with flag arguments to %pGp in the future.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20211019142621.2810043-6-willy@infradead.org
Commit 110860541f ("mm/secretmem: use refcount_t instead of atomic_t")
attempted to fix the problem of secretmem_users wrapping to zero and
allowing suspend once again.
But it was reverted in commit 87066fdd2e ("Revert 'mm/secretmem: use
refcount_t instead of atomic_t'") because of the problems it caused - a
refcount_t was not semantically the right type to use.
Instead prevent secretmem_users from wrapping to zero by forbidding new
users if the number of users has wrapped from positive to negative.
This stops a long way short of reaching the necessary 4 billion users
where it wraps to zero again, so there's no need to be clever with
special anti-wrap types or checking the return value from atomic_inc().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 110860541f.
Converting the "secretmem_users" counter to a refcount is incorrect,
because a refcount is special in zero and can't just be incremented (but
a count of users is not, and "no users" is actually perfectly valid and
not a sign of a free'd resource).
Reported-by: syzbot+75639e6a0331cd61d3e2@syzkaller.appspotmail.com
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: Jordy Zomer <jordy@jordyzomer.github.io>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a new FOLL_NOFAULT flag that causes get_user_pages to return
-EFAULT when it would otherwise trigger a page fault. This is roughly
similar to FOLL_FAST_ONLY but available on all architectures, and less
fragile.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Vladimir Zapolskiy reports:
Commit a7259df767 ("memblock: make memblock_find_in_range method
private") invokes a kernel panic while running kmemleak on OF platforms
with nomaped regions:
Unable to handle kernel paging request at virtual address fff000021e00000
[...]
scan_block+0x64/0x170
scan_gray_list+0xe8/0x17c
kmemleak_scan+0x270/0x514
kmemleak_write+0x34c/0x4ac
The memory allocated from memblock is registered with kmemleak, but if
it is marked MEMBLOCK_NOMAP it won't have linear map entries so an
attempt to scan such areas will fault.
Ideally, memblock_mark_nomap() would inform kmemleak to ignore
MEMBLOCK_NOMAP memory, but it can be called before kmemleak interfaces
operating on physical addresses can use __va() conversion.
Make sure that functions that mark allocated memory as MEMBLOCK_NOMAP
take care of informing kmemleak to ignore such memory.
Link: https://lore.kernel.org/all/8ade5174-b143-d621-8c8e-dc6a1898c6fb@linaro.org
Link: https://lore.kernel.org/all/c30ff0a2-d196-c50d-22f0-bd50696b1205@quicinc.com
Fixes: a7259df767 ("memblock: make memblock_find_in_range method private")
Reported-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a new fault_in_iov_iter_writeable helper for safely faulting
in an iterator for writing. Uses get_user_pages() to fault in the pages
without actually writing to them, which would be destructive.
We'll use fault_in_iov_iter_writeable in gfs2 once we've determined that
the iterator passed to .read_iter isn't in memory.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Decrease nr_thps counter in file's mapping to ensure that the page cache
won't be dropped excessively on file write access if page has been
already split.
I've tried a test scenario running a big binary, kernel remaps it with
THPs, then force a THP split with /sys/kernel/debug/split_huge_pages.
During any further open of that binary with O_RDWR or O_WRITEONLY kernel
drops page cache for it, because of non-zero thps counter.
Link: https://lkml.kernel.org/r/20211012120237.2600-1-m.szyprowski@samsung.com
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 09d91cda0e ("mm,thp: avoid writes to file with THP in pagecache")
Fixes: 06d3eff62d ("mm/thp: fix node page state in split_huge_page_to_list()")
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: <sfoon.kim@samsung.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When sysfs_slab_add failed, we shouldn't call debugfs_slab_add() for s
because s will be freed soon. And slab_debugfs_fops will use s later
leading to a use-after-free.
Link: https://lkml.kernel.org/r/20210916123920.48704-5-linmiaohe@huawei.com
Fixes: 64dd68497b ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In error path, the random_seq of slub cache might be leaked. Fix this
by using __kmem_cache_release() to release all the relevant resources.
Link: https://lkml.kernel.org/r/20210916123920.48704-4-linmiaohe@huawei.com
Fixes: 210e7a43fa ("mm: SLUB freelist randomization")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If object's reuse is delayed, it will be excluded from the reconstructed
freelist. But we forgot to adjust the cnt accordingly. So there will
be a mismatch between reconstructed freelist depth and cnt. This will
lead to free_debug_processing() complaining about freelist count or a
incorrect slub inuse count.
Link: https://lkml.kernel.org/r/20210916123920.48704-3-linmiaohe@huawei.com
Fixes: c3895391df ("kasan, slub: fix handling of kasan_slab_free hook")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Fixups for slub".
This series contains various bug fixes for slub. We fix memoryleak,
use-afer-free, NULL pointer dereferencing and so on in slub. More
details can be found in the respective changelogs.
This patch (of 5):
It's possible that __seq_open_private() will return NULL. So we should
check it before using lest dereferencing NULL pointer. And in error
paths, we forgot to release private buffer via seq_release_private().
Memory will leak in these paths.
Link: https://lkml.kernel.org/r/20210916123920.48704-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210916123920.48704-2-linmiaohe@huawei.com
Fixes: 64dd68497b ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem=[X][G|M] is broken on ARM64 platform, there are cases that even
type.cnt is 1, but total_size is not 0 because regions are merged into
1. So only check 'cnt' is not enough, total_size should be used,
othersize bootargs 'mem=[X][G|B]' not work anymore.
Link: https://lkml.kernel.org/r/20210930024437.32598-1-peng.fan@oss.nxp.com
Fixes: e888fa7bb8 ("memblock: Check memory add/cap ordering")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The node demotion order needs to be updated during CPU hotplug. Because
whether a NUMA node has CPU may influence the demotion order. The
update function should be called during CPU online/offline after the
node_states[N_CPU] has been updated. That is done in
CPUHP_AP_ONLINE_DYN during CPU online and in CPUHP_MM_VMSTAT_DEAD during
CPU offline. But in commit 884a6e5d1f ("mm/migrate: update node
demotion order on hotplug events"), the function to update node demotion
order is called in CPUHP_AP_ONLINE_DYN during CPU online/offline. This
doesn't satisfy the order requirement.
For example, there are 4 CPUs (P0, P1, P2, P3) in 2 sockets (P0, P1 in S0
and P2, P3 in S1), the demotion order is
- S0 -> NUMA_NO_NODE
- S1 -> NUMA_NO_NODE
After P2 and P3 is offlined, because S1 has no CPU now, the demotion
order should have been changed to
- S0 -> S1
- S1 -> NO_NODE
but it isn't changed, because the order updating callback for CPU
hotplug doesn't see the new nodemask. After that, if P1 is offlined,
the demotion order is changed to the expected order as above.
So in this patch, we added CPUHP_AP_MM_DEMOTION_ONLINE and
CPUHP_MM_DEMOTION_DEAD to be called after CPUHP_AP_ONLINE_DYN and
CPUHP_MM_VMSTAT_DEAD during CPU online and offline, and register the
update function on them.
Link: https://lkml.kernel.org/r/20210929060351.7293-1-ying.huang@intel.com
Fixes: 884a6e5d1f ("mm/migrate: update node demotion order on hotplug events")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Once upon a time, the node demotion updates were driven solely by memory
hotplug events. But now, there are handlers for both CPU and memory
hotplug.
However, the #ifdef around the code checks only memory hotplug. A
system that has HOTPLUG_CPU=y but MEMORY_HOTPLUG=n would miss CPU
hotplug events.
Update the #ifdef around the common code. Add memory and CPU-specific
#ifdefs for their handlers. These memory/CPU #ifdefs avoid unused
function warnings when their Kconfig option is off.
[arnd@arndb.de: rework hotplug_memory_notifier() stub]
Link: https://lkml.kernel.org/r/20211013144029.2154629-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20210924161255.E5FE8F7E@davehans-spike.ostc.intel.com
Fixes: 884a6e5d1f ("mm/migrate: update node demotion order on hotplug events")
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/migrate: 5.15 fixes for automatic demotion", v2.
This contains two fixes for the "automatic demotion" code which was
merged into 5.15:
* Fix memory hotplug performance regression by watching
suppressing any real action on irrelevant hotplug events.
* Ensure CPU hotplug handler is registered when memory hotplug
is disabled.
This patch (of 2):
== tl;dr ==
Automatic demotion opted for a simple, lazy approach to handling hotplug
events. This noticeably slows down memory hotplug[1]. Optimize away
updates to the demotion order when memory hotplug events should have no
effect.
This has no effect on CPU hotplug. There is no known problem on the CPU
side and any work there will be in a separate series.
== Background ==
Automatic demotion is a memory migration strategy to ensure that new
allocations have room in faster memory tiers on tiered memory systems.
The kernel maintains an array (node_demotion[]) to drive these
migrations.
The node_demotion[] path is calculated by starting at nodes with CPUs
and then "walking" to nodes with memory. Only hotplug events which
online or offline a node with memory (N_ONLINE) or CPUs (N_CPU) will
actually affect the migration order.
== Problem ==
However, the current code is lazy. It completely regenerates the
migration order on *any* CPU or memory hotplug event. The logic was
that these events are extremely rare and that the overhead from
indiscriminate order regeneration is minimal.
Part of the update logic involves a synchronize_rcu(), which is a pretty
big hammer. Its overhead was large enough to be detected by some 0day
tests that watch memory hotplug performance[1].
== Solution ==
Add a new helper (node_demotion_topo_changed()) which can differentiate
between superfluous and impactful hotplug events. Skip the expensive
update operation for superfluous events.
== Aside: Locking ==
It took me a few moments to declare the locking to be safe enough for
node_demotion_topo_changed() to work. It all hinges on the memory
hotplug lock:
During memory hotplug events, 'mem_hotplug_lock' is held for write.
This ensures that two memory hotplug events can not be called
simultaneously.
CPU hotplug has a similar lock (cpuhp_state_mutex) which also provides
mutual exclusion between CPU hotplug events. In addition, the demotion
code acquire and hold the mem_hotplug_lock for read during its CPU
hotplug handlers. This provides mutual exclusion between the demotion
memory hotplug callbacks and the CPU hotplug callbacks.
This effectively allows treating the migration target generation code to
act as if it is single-threaded.
1. https://lore.kernel.org/all/20210905135932.GE15026@xsang-OptiPlex-9020/
Link: https://lkml.kernel.org/r/20210924161251.093CCD06@davehans-spike.ostc.intel.com
Link: https://lkml.kernel.org/r/20210924161253.D7673E31@davehans-spike.ostc.intel.com
Fixes: 884a6e5d1f ("mm/migrate: update node demotion order on hotplug events")
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct io_comp_batch contains a list head and a completion handler, which
will allow completions to more effciently completed batches of IO.
For now, no functional changes in this patch, we just define the
io_comp_batch structure and add the argument to the file_operations iopoll
handler.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Turn iov_iter_fault_in_readable into a function that returns the number
of bytes not faulted in, similar to copy_to_user, instead of returning a
non-zero value when any of the requested pages couldn't be faulted in.
This supports the existing users that require all pages to be faulted in
as well as new users that are happy if any pages can be faulted in.
Rename iov_iter_fault_in_readable to fault_in_iov_iter_readable to make
sure this change doesn't silently break things.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Turn fault_in_pages_{readable,writeable} into versions that return the
number of bytes not faulted in, similar to copy_to_user, instead of
returning a non-zero value when any of the requested pages couldn't be
faulted in. This supports the existing users that require all pages to
be faulted in as well as new users that are happy if any pages can be
faulted in.
Rename the functions to fault_in_{readable,writeable} to make sure
this change doesn't silently break things.
Neither of these functions is entirely trivial and it doesn't seem
useful to inline them, so move them to mm/gup.c.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Replace the blk_poll interface that requires the caller to keep a queue
and cookie from the submissions with polling based on the bio.
Polling for the bio itself leads to a few advantages:
- the cookie construction can made entirely private in blk-mq.c
- the caller does not need to remember the request_queue and cookie
separately and thus sidesteps their lifetime issues
- keeping the device and the cookie inside the bio allows to trivially
support polling BIOs remapping by stacking drivers
- a lot of code to propagate the cookie back up the submission path can
be removed entirely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Unlike the RWF_HIPRI userspace ABI which is intentionally kept vague,
the bio flag is specific to the polling implementation, so rename and
document it properly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Switch the boolean spin argument to blk_poll to passing a set of flags
instead. This will allow to control polling behavior in a more fine
grained way.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-10-hch@lst.de
[axboe: adapt to changed io_uring iopoll]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Various files have acquired spurious includes of <linux/blkdev.h> over
time. Remove them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move inode_to_bdi out of line to avoid having to include blkdev.h.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need to pull blk-cgroup.h and thus blkdev.h in here, so
break the include chain.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Transform write_one_page() into folio_write_one() and add a compatibility
wrapper. Also move the declaration to pagemap.h as this is page cache
functionality that doesn't need to be used by the rest of the kernel.
Saves 58 bytes of kernel text. While folio_write_one() is 101 bytes
smaller than write_one_page(), the inlined call to page_folio() expands
each caller. There are fewer than ten callers so it doesn't seem worth
putting a wrapper in the core.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Allow filemap_get_folio() to wait for writeback to complete (if the
filesystem wants that behaviour). This is the folio equivalent of
grab_cache_page_write_begin(), which is moved into the folio-compat
file as a reminder to migrate all the code using it. This paves the
way for getting rid of AOP_FLAG_NOFS once grab_cache_page_write_begin()
is removed.
Kernel grows by 11 bytes. filemap_get_folio() grows by 33 bytes but
grab_cache_page_write_begin() shrinks by 22 bytes to make up for it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
filemap_get_folio() is a replacement for find_get_page().
Turn pagecache_get_page() into a wrapper around __filemap_get_folio().
Remove find_lock_head() as this use case is now covered by
filemap_get_folio().
Reduces overall kernel size by 209 bytes. __filemap_get_folio() is
316 bytes shorter than pagecache_get_page() was, but the new
pagecache_get_page() wrapper is 99 bytes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The pagecache only contains folios, so indicate that this is definitely
not a tail page. Shrinks mapping_get_entry() by 56 bytes, but grows
pagecache_get_page() by 21 bytes as gcc makes slightly different hot/cold
code decisions. A net reduction of 35 bytes of text.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Convert __add_to_page_cache_locked() into __filemap_add_folio().
Add an assertion to it that (for !hugetlbfs), the folio is naturally
aligned within the file. Move the prototype from mm.h to pagemap.h.
Convert add_to_page_cache_lru() into filemap_add_folio(). Add a
compatibility wrapper for unconverted callers.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement __page_cache_alloc as a wrapper around filemap_alloc_folio
to allow filesystems to be converted at our leisure. Increases
kernel text size by 133 bytes, mostly in cachefiles_read_backing_file().
pagecache_get_page() shrinks by 32 bytes, though.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The __folio_alloc(), __folio_alloc_node() and folio_alloc() functions
are mostly for type safety, but they also ensure that the page allocator
allocates a compound page and initialises the deferred list if the page
is large enough to have one.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement lru_cache_add() as a wrapper around folio_add_lru().
Saves 159 bytes of kernel text due to removing calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This saves five calls to compound_head(), totalling 60 bytes of text.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This is the folio equivalent of page_evictable(). Unfortunately, it's
different from !folio_test_unevictable(), but I think it's used in places
where you have to be a VM expert and can reasonably be expected to know
the difference.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This nets us 178 bytes of savings from removing calls to compound_head.
The three callers all grow a little, but each of them will be converted
to use folios soon, so that's fine.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement redirty_page_for_writepage() as a wrapper around
folio_redirty_for_writepage(). Account the number of pages in the
folio, add kernel-doc and move the prototype to writeback.h.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Account the number of pages in the folio that we're redirtying.
Turn account_page_dirty() into a wrapper around it. Also turn
the comment on folio_account_redirty() into kernel-doc and
edit it slightly so it makes sense to its potential callers.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Transform clear_page_dirty_for_io() into folio_clear_dirty_for_io()
and add a compatibility wrapper. Also move the declaration to pagemap.h
as this is page cache functionality that doesn't need to be used by the
rest of the kernel.
Increases the size of the kernel by 79 bytes. While we remove a few
calls to compound_head(), we add a call to folio_nr_pages() to get the
stats correct for the eventual support of multi-page folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Turn __cancel_dirty_page() into __folio_cancel_dirty() and add wrappers.
Move the prototypes into pagemap.h since this is page cache functionality.
Saves 44 bytes of kernel text in total; 33 bytes from __folio_cancel_dirty
and 11 from two callers of cancel_dirty_page().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Get the statistics right; compound pages were being accounted as a
single page. This didn't matter before now as no filesystem which
supported compound pages did writeback. Also move the declaration
to pagemap.h since this is part of the page cache. Add a wrapper for
account_page_cleaned().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement __set_page_dirty_nobuffers() as a wrapper around
filemap_dirty_folio(). Eventually folio_mark_dirty() will pass
the folio's mapping to the address space's ->dirty_folio()
operation, so add the parameter to filemap_dirty_folio() now.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Rename writeback_dirty_page() to writeback_dirty_folio() and
wait_on_page_writeback() to folio_wait_writeback().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Turn __set_page_dirty() into a wrapper around __folio_mark_dirty().
Convert account_page_dirtied() into folio_account_dirtied() and account
the number of pages in the folio to support multi-page folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement set_page_dirty() as a wrapper around folio_mark_dirty().
There is no change to filesystems as they were already being called
with the compound_head of the page being marked dirty. We avoid
several calls to compound_head(), both statically (through
using folio_test_dirty() instead of PageDirty() and dynamically by
calling folio_mapping() instead of page_mapping().
Also return bool instead of int to show the range of values actually
returned, and add kernel-doc.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Rename set_page_writeback() to folio_start_writeback() to match
folio_end_writeback(). Do not bother with wrappers that return void;
callers are perfectly capable of ignoring return values.
Add wrappers for set_page_writeback(), set_page_writeback_keepwrite() and
test_set_page_writeback() for compatibililty with existing filesystems.
The main advantage of this patch is getting the statistics right,
although it does eliminate a couple of calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
test_clear_page_writeback() is actually an mm-internal function, although
it's named as if it's a pagecache function. Move it to mm/internal.h,
rename it to __folio_end_writeback() and change the return type to bool.
The conversion from page to folio is mostly about accounting the number
of pages being written back, although it does eliminate a couple of
calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Allow for accounting N pages at once instead of one page at a time.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
When batching events (such as writing back N pages in a single I/O), it
is better to do one flex_proportion operation instead of N. There is
only one caller of __fprop_inc_percpu_max(), and it's the one we're
going to change in the next patch, so rename it instead of adding a
compatibility wrapper.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
This is the folio equivalent of migrate_page_copy(), which is retained
as a wrapper for filesystems which are not yet converted to folios.
Also convert copy_huge_page() to folio_copy().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Turn migrate_page_states() into a wrapper around folio_migrate_flags().
Also convert two functions only called from folio_migrate_flags() to
be folio-based. ksm_migrate_page() becomes folio_migrate_ksm() and
copy_page_owner() becomes folio_copy_owner(). folio_migrate_flags()
alone shrinks by two thirds -- 1967 bytes down to 642 bytes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reimplement migrate_page_move_mapping() as a wrapper around
folio_migrate_mapping(). Saves 193 bytes of kernel text.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Transform page_mkclean() into folio_mkclean() and add a page_mkclean()
wrapper around folio_mkclean().
folio_mkclean is 15 bytes smaller than page_mkclean, but the kernel
is enlarged by 33 bytes due to inlining page_folio() into each caller.
This will go away once the callers are converted to use folio_mkclean().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Convert mark_page_accessed() to folio_mark_accessed(). It already
operated on the entire compound page, but now we can avoid calling
compound_head quite so many times. Shrinks the function from 424 bytes
to 295 bytes (shrinking by 129 bytes). The compatibility wrapper is 30
bytes, plus the 8 bytes for the exported symbol means the kernel shrinks
by 91 bytes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This replaces activate_page() and eliminates lots of calls to
compound_head(). Saves net 118 bytes of kernel text. There are still
some redundant calls to page_folio() here which will be removed when
pagevec_lru_move_fn() is converted to use folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This is a default implementation which calls flush_dcache_page() on
each page in the folio. If architectures can do better, they should
implement their own version of it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Instead of duplicating the same code in two places use the newly added
pidfd_get_task() helper. This fixes an (unimportant for now) bug where
PIDTYPE_PID is used whereas PIDTYPE_TGID should have been used.
Link: https://lore.kernel.org/r/20211004125050.1153693-3-christian.brauner@ubuntu.com
Link: https://lore.kernel.org/r/20211011133245.1703103-3-brauner@kernel.org
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Bobrowski <repnop@google.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Reviewed-by: Matthew Bobrowski <repnop@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Vladimir Zapolskiy reports:
commit a7259df767 ("memblock: make memblock_find_in_range method private")
invokes a kernel panic while running kmemleak on OF platforms with nomaped
regions:
Unable to handle kernel paging request at virtual address fff000021e00000
[...]
scan_block+0x64/0x170
scan_gray_list+0xe8/0x17c
kmemleak_scan+0x270/0x514
kmemleak_write+0x34c/0x4ac
Indeed, NOMAP regions don't have linear map entries so an attempt to scan
these areas would fault.
Prevent such faults by excluding NOMAP regions from kmemleak.
Link: https://lore.kernel.org/all/8ade5174-b143-d621-8c8e-dc6a1898c6fb@linaro.org
Fixes: a7259df767 ("memblock: make memblock_find_in_range method private")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Today when a signal is delivered with a handler of SIG_DFL whose
default behavior is to generate a core dump not only that process but
every process that shares the mm is killed.
In the case of vfork this looks like a real world problem. Consider
the following well defined sequence.
if (vfork() == 0) {
execve(...);
_exit(EXIT_FAILURE);
}
If a signal that generates a core dump is received after vfork but
before the execve changes the mm the process that called vfork will
also be killed (as the mm is shared).
Similarly if the execve fails after the point of no return the kernel
delivers SIGSEGV which will kill both the exec'ing process and because
the mm is shared the process that called vfork as well.
As far as I can tell this behavior is a violation of people's
reasonable expectations, POSIX, and is unnecessarily fragile when the
system is low on memory.
Solve this by making a userspace visible change to only kill a single
process/thread group. This is possible because Jann Horn recently
modified[1] the coredump code so that the mm can safely be modified
while the coredump is happening. With LinuxThreads long gone I don't
expect anyone to have a notice this behavior change in practice.
To accomplish this move the core_state pointer from mm_struct to
signal_struct, which allows different thread groups to coredump
simultatenously.
In zap_threads remove the work to kill anything except for the current
thread group.
v2: Remove core_state from the VM_BUG_ON_MM print to fix
compile failure when CONFIG_DEBUG_VM is enabled.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
[1] a07279c9a8 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Link: https://lkml.kernel.org/r/87y27mvnke.fsf@disp2133
Link: https://lkml.kernel.org/r/20211007144701.67592574@canb.auug.org.au
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Architectures supported by KASAN_HW_TAGS can provide an asymmetric mode
of execution. On an MTE enabled arm64 hw for example this can be
identified with the asymmetric tagging mode of execution. In particular,
when such a mode is present, the CPU triggers a fault on a tag mismatch
during a load operation and asynchronously updates a register when a tag
mismatch is detected during a store operation.
Extend the KASAN HW execution mode kernel command line parameter to
support asymmetric mode.
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20211006154751.4463-6-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
After merging async mode for KASAN_HW_TAGS a duplicate of the
kasan_flag_async flag was left erroneously inside the code.
Remove the duplicate.
Note: This change does not bring functional changes to the code
base.
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20211006154751.4463-2-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Rename coredump_exit_mm to coredump_task_exit and call it from do_exit
before PTRACE_EVENT_EXIT, and before any cleanup work for a task
happens. This ensures that an accurate copy of the process can be
captured in the coredump as no cleanup for the process happens before
the coredump completes. This also ensures that PTRACE_EVENT_EXIT
will not be visited by any thread until the coredump is complete.
Add a new flag PF_POSTCOREDUMP so that tasks that have passed through
coredump_task_exit can be recognized and ignored in zap_process.
Now that all of the coredumping happens before exit_mm remove code to
test for a coredump in progress from mm_release.
Replace "may_ptrace_stop()" with a simple test of "current->ptrace".
The other tests in may_ptrace_stop all concern avoiding stopping
during a coredump. These tests are no longer necessary as it is now
guaranteed that fatal_signal_pending will be set if the code enters
ptrace_stop during a coredump. The code in ptrace_stop is guaranteed
not to stop if fatal_signal_pending returns true.
Until this change "ptrace_event(PTRACE_EVENT_EXIT)" could call
ptrace_stop without fatal_signal_pending being true, as signals are
dequeued in get_signal before calling do_exit. This is no longer
an issue as "ptrace_event(PTRACE_EVENT_EXIT)" is no longer reached
until after the coredump completes.
Link: https://lkml.kernel.org/r/874kaax26c.fsf@disp2133
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Separate the coredump logic from the ordinary exit_mm logic
by moving the coredump logic out of exit_mm into it's own
function coredump_exit_mm.
Link: https://lkml.kernel.org/r/87a6k2x277.fsf@disp2133
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Convert __page_rmapping to folio_raw_mapping and move it to mm/internal.h.
It's only a couple of instructions (load and mask), so it's definitely
going to be cheaper to inline it than call it. Leave page_rmapping
out of line. Change page_anon_vma() to not call folio_raw_mapping() --
it's more efficient to do the subtraction than the mask.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This function already assumed it was being passed a head page. No real
change here, except that thp_nr_pages() compiles away on kernels with
THP compiled out while folio_nr_pages() is always present. Also convert
page_memcg_rcu() to folio_memcg_rcu().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
These are the folio equivalents of relock_page_lruvec_irq() and
folio_lruvec_relock_irqsave(). Also convert page_matches_lruvec()
to folio_matches_lruvec().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
These are the folio equivalents of lock_page_lruvec() and similar
functions. Also convert lruvec_memcg_debug() to take a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This replaces mem_cgroup_page_lruvec(). All callers converted.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This saves dozens of bytes of text by eliminating a lot of calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
These are the folio equivalents of lock_page_memcg() and
unlock_page_memcg().
lock_page_memcg() and unlock_page_memcg() have too many callers to be
easily replaced in a single patch, so reimplement them as wrappers for
now to be cleaned up later when enough callers have been converted to
use folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The page was only being used for the memcg and to gather trace
information, so this is a simple conversion. The only caller of
mem_cgroup_track_foreign_dirty() will be converted to folios in a later
patch, so doing this now makes that patch simpler.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Convert all callers of mem_cgroup_migrate() to call page_folio() first.
They all look like they're using head pages already, but this proves it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Convert all the callers to call page_folio(). Most of them were already
using a head page, but a few of them I can't prove were, so this may
actually fix a bug.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Use a folio rather than a page to ensure that we're only operating on
base or head pages, and not tail pages.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Convert all callers of mem_cgroup_charge() to call page_folio() on the
page they're currently passing in. Many of them will be converted to
use folios themselves soon.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The memcg_data is only set on the head page, so enforce that by
typing it as a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
memcg information is only stored in the head page, so the memcg
subsystem needs to assure that all accesses are to the head page.
The first step is converting page_memcg() to folio_memcg().
The callers of page_memcg() and PageMemcgKmem() are not yet ready to be
converted to use folios, so retain them as wrappers around folio_memcg()
and folio_memcg_kmem(). They will be converted in a later patch set.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
memcg_check_events only uses the page's nid, so call page_to_nid in the
callers to make the interface easier to understand.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Opencode this one-line function in its three callers.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
By using the node id in mem_cgroup_update_tree(), we can delete
soft_limit_tree_from_page() and mem_cgroup_page_nodeinfo(). Saves 42
bytes of kernel text on my config.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The last use of 'page' was removed by commit 468c398233 ("mm:
memcontrol: switch to native NR_ANON_THPS counter"), so we can now remove
the parameter from the function.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This function is the equivalent of page_mapped(). It is slightly
shorter as we do not need to handle the PageTail() case. Reimplement
page_mapped() as a wrapper around folio_mapped(). folio_mapped()
is 13 bytes smaller than page_mapped(), but the page_mapped() wrapper
is 30 bytes, for a net increase of 17 bytes of text.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
end_page_private_2() becomes folio_end_private_2(),
wait_on_page_private_2() becomes folio_wait_private_2() and
wait_on_page_private_2_killable() becomes folio_wait_private_2_killable().
Adjust the fscache equivalents to call page_folio() before calling these
functions to avoid adding wrappers. Ends up costing 1 byte of text
in ceph & netfs, but the core shrinks by three calls to page_folio().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reinforce that page flags are actually in the head page by changing the
type from page to folio. Increases the size of cachefiles by two bytes,
but the kernel core is unchanged in size.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Convert wake_up_page_bit() to folio_wake_bit(). All callers have a folio,
so use it directly. Saves 66 bytes of text in end_page_private_2().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Rename wait_on_page_bit() to folio_wait_bit(). We must always wait on
the folio, otherwise we won't be woken up due to the tail page hashing
to a different bucket from the head page.
This commit shrinks the kernel by 770 bytes, mostly due to moving
the page waitqueue lookup into folio_wait_bit_common().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Move wait_for_stable_page() into the folio compatibility file.
folio_wait_stable() avoids a call to compound_head() and is 14 bytes
smaller than wait_for_stable_page() was. The net text size grows by 16
bytes as a result of this patch. We can also remove thp_head() as this
was the last user.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
wait_on_page_writeback_killable() only has one caller, so convert it to
call folio_wait_writeback_killable(). For the wait_on_page_writeback()
callers, add a compatibility wrapper around folio_wait_writeback().
Turning PageWriteback() into folio_test_writeback() eliminates a call
to compound_head() which saves 8 bytes and 15 bytes in the two
functions. Unfortunately, that is more than offset by adding the
wait_on_page_writeback compatibility wrapper for a net increase in text
of 7 bytes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Add an end_page_writeback() wrapper function for users that are not yet
converted to folios.
folio_end_writeback() is less than half the size of end_page_writeback()
at just 105 bytes compared to 228 bytes, due to removing all the
compound_head() calls. The 30 byte wrapper function makes this a net
saving of 93 bytes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Convert rotate_reclaimable_page() to folio_rotate_reclaimable(). This
eliminates all five of the calls to compound_head() in this function,
saving 75 bytes at the cost of adding 15 bytes to its one caller,
end_page_writeback(). We also save 36 bytes from pagevec_move_tail_fn()
due to using folios there. Net 96 bytes savings.
Also move its declaration to mm/internal.h as it's only used by filemap.c.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Convert __lock_page_or_retry() to __folio_lock_or_retry(). This actually
saves 4 bytes in the only caller of lock_page_or_retry() (due to better
register allocation) and saves the 14 byte cost of calling page_folio()
in __folio_lock_or_retry() for a total saving of 18 bytes. Also use
a bool for the return type.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Also add folio_wait_locked_killable(). Turn wait_on_page_locked() and
wait_on_page_locked_killable() into wrappers. This eliminates a call
to compound_head() from each call-site, reducing text size by 193 bytes
for me.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
There aren't any actual callers of lock_page_async(), so remove it.
Convert filemap_update_page() to call __folio_lock_async().
__folio_lock_async() is 21 bytes smaller than __lock_page_async(),
but the real savings come from using a folio in filemap_update_page(),
shrinking it from 515 bytes to 404 bytes, saving 110 bytes. The text
shrinks by 132 bytes in total.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
This is like lock_page_killable() but for use by callers who
know they have a folio. Convert __lock_page_killable() to be
__folio_lock_killable(). This saves one call to compound_head() per
contended call to lock_page_killable().
__folio_lock_killable() is 19 bytes smaller than __lock_page_killable()
was. filemap_fault() shrinks by 74 bytes and __lock_page_or_retry()
shrinks by 71 bytes. That's a total of 164 bytes of text saved.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
This is like lock_page() but for use by callers who know they have a folio.
Convert __lock_page() to be __folio_lock(). This saves one call to
compound_head() per contended call to lock_page().
Saves 455 bytes of text; mostly from improved register allocation and
inlining decisions. __folio_lock is 59 bytes while __lock_page was 79.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Convert unlock_page() to call folio_unlock(). By using a folio we
avoid a call to compound_head(). This shortens the function from 39
bytes to 25 and removes 4 instructions on x86-64. Because we still
have unlock_page(), it's a net increase of 16 bytes of text for the
kernel as a whole, but any path that uses folio_unlock() will execute
4 fewer instructions.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
These are the folio equivalent of page_mapping() and page_file_mapping().
Add an out-of-line page_mapping() wrapper around folio_mapping()
in order to prevent the page_folio() call from bloating every caller
of page_mapping(). Adjust page_file_mapping() and page_mapping_file()
to use folios internally. Rename __page_file_mapping() to
swapcache_mapping() and change it to take a folio.
This ends up saving 122 bytes of text overall. folio_mapping() is
45 bytes shorter than page_mapping() was, but the new page_mapping()
wrapper is 30 bytes. The major reduction is a few bytes less in dozens
of nfs functions (which call page_file_mapping()). Most of these appear
to be a slight change in gcc's register allocation decisions, which allow:
48 8b 56 08 mov 0x8(%rsi),%rdx
48 8d 42 ff lea -0x1(%rdx),%rax
83 e2 01 and $0x1,%edx
48 0f 44 c6 cmove %rsi,%rax
to become:
48 8b 46 08 mov 0x8(%rsi),%rax
48 8d 78 ff lea -0x1(%rax),%rdi
a8 01 test $0x1,%al
48 0f 44 fe cmove %rsi,%rdi
for a reduction of a single byte. Once the NFS client is converted to
use folios, this entire sequence will disappear.
Also add folio_mapping() documentation.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
This is the equivalent of page_cache_get_speculative(). Also add
folio_ref_try_add_rcu (the equivalent of page_cache_add_speculative)
and folio_get_unless_zero() (the equivalent of get_page_unless_zero()).
The new kernel-doc attempts to explain from the user's point of view
when to use folio_try_get_rcu() and when to use folio_get_unless_zero(),
because there seems to be some confusion currently between the users of
page_cache_get_speculative() and get_page_unless_zero().
Reimplement page_cache_add_speculative() and page_cache_get_speculative()
as wrappers around the folio equivalents, but leave get_page_unless_zero()
alone for now. This commit reduces text size by 3 bytes due to slightly
different register allocation & instruction selections.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
We get an unexpected value of /proc/sys/vm/overcommit_memory after
running the following program:
int main()
{
int fd = open("/proc/sys/vm/overcommit_memory", O_RDWR);
write(fd, "1", 1);
write(fd, "2", 1);
close(fd);
}
write(fd, "2", 1) will pass *ppos = 1 to proc_dointvec_minmax.
proc_dointvec_minmax will return 0 without setting new_policy.
t.data = &new_policy;
ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos)
-->do_proc_dointvec
-->__do_proc_dointvec
if (write) {
if (proc_first_pos_non_zero_ignore(ppos, table))
goto out;
sysctl_overcommit_memory = new_policy;
so sysctl_overcommit_memory will be set to an uninitialized value.
Check whether new_policy has been changed by proc_dointvec_minmax.
Link: https://lkml.kernel.org/r/20210923020524.13289-1-chenjun102@huawei.com
Fixes: 56f3547bfa ("mm: adjust vm_committed_as_batch according to vm overcommit policy")
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Rui Xiang <rui.xiang@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The paired pte_unmap() call is missing before the
dev_pagemap_mapping_shift() returns. So fix it.
David says:
"I guess this code never runs on 32bit / highmem, that's why we didn't
notice so far".
[akpm@linux-foundation.org: cleanup]
Link: https://lkml.kernel.org/r/20210923122642.4999-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sync up MR_DEMOTION to migrate_reason_names and add a synch prompt.
Link: https://lkml.kernel.org/r/20210921064553.293905-3-o451686892@gmail.com
Fixes: 26aa2d199d ("mm/migrate: demote pages during reclaim")
Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Xu <weixugc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sync up MR_CONTIG_RANGE and MR_LONGTERM_PIN to migrate_reason_names.
Link: https://lkml.kernel.org/r/20210921064553.293905-2-o451686892@gmail.com
Fixes: 310253514b ("mm/migrate: rename migration reason MR_CMA to MR_CONTIG_RANGE")
Fixes: d1e153fea2 ("mm/gup: migrate pinned pages out of movable zone")
Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Xu <weixugc@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel test robot reported the regression of fio.write_iops[1] with
commit 8cc621d2f4 ("mm: fs: invalidate BH LRU during page migration").
Since lru_add_drain is called frequently, invalidate bh_lrus there could
increase bh_lrus cache miss ratio, which needs more IO in the end.
This patch moves the bh_lrus invalidation from the hot path( e.g.,
zap_page_range, pagevec_release) to cold path(i.e., lru_add_drain_all,
lru_cache_disable).
Zhengjun Xing confirmed
"I test the patch, the regression reduced to -2.9%"
[1] https://lore.kernel.org/lkml/20210520083144.GD14190@xsang-OptiPlex-9020/
[2] 8cc621d2f4, mm: fs: invalidate BH LRU during page migration
Link: https://lkml.kernel.org/r/20210907212347.1977686-1-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Reviewed-by: Chris Goldsworthy <cgoldswo@codeaurora.org>
Tested-by: "Xing, Zhengjun" <zhengjun.xing@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the case of SHMEM_HUGE_WITHIN_SIZE, the page index is not rounded up
correctly. When the page index points to the first page in a huge page,
round_up() cannot bring it to the end of the huge page, but to the end
of the previous one.
An example:
HPAGE_PMD_NR on my machine is 512(2 MB huge page size). After
allcoating a 3000 KB buffer, I access it at location 2050 KB. In
shmem_is_huge(), the corresponding index happens to be 512. After
rounded up by HPAGE_PMD_NR, it will still be 512 which is smaller than
i_size, and shmem_is_huge() will return true. As a result, my buffer
takes an additional huge page, and that shouldn't happen when
shmem_enabled is set to within_size.
Link: https://lkml.kernel.org/r/20210909032007.18353-1-liuyuntao10@huawei.com
Fixes: f3f0e1d215 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Liu Yuntao <liuyuntao10@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: wuxu.wu <wuxu.wu@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit fcc00621d8 ("mm/hwpoison: retry with shake_page() for
unhandlable pages") changed the return value of __get_hwpoison_page() to
retry for transiently unhandlable cases. However, __get_hwpoison_page()
currently fails to properly judge buddy pages as handlable, so hard/soft
offline for buddy pages always fail as "unhandlable page". This is
totally regrettable.
So let's add is_free_buddy_page() in HWPoisonHandlable(), so that
__get_hwpoison_page() returns different return values between buddy
pages and unhandlable pages as intended.
Link: https://lkml.kernel.org/r/20210909004131.163221-1-naoya.horiguchi@linux.dev
Fixes: fcc00621d8 ("mm/hwpoison: retry with shake_page() for unhandlable pages")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Prior to the commit 7e1c0d6f58 ("memcg: switch lruvec stats to rstat")
and the commit aa48e47e39 ("memcg: infrastructure to flush memcg
stats"), each lruvec memcg stats can be off by (nr_cgroups * nr_cpus *
32) at worst and for unbounded amount of time. The commit aa48e47e39
moved the lruvec stats to rstat infrastructure and the commit
7e1c0d6f58 bounded the error for all the lruvec stats to (nr_cpus *
32) at worst for at most 2 seconds. More specifically it decoupled the
number of stats and the number of cgroups from the error rate.
However this reduction in error comes with the cost of triggering the
slowpath of stats update more frequently. Previously in the slowpath
the kernel adds the stats up the memcg tree. After aa48e47e39, the
kernel triggers the asyn lruvec stats flush through queue_work(). This
causes regression reports from 0day kernel bot [1] as well as from
phoronix test suite [2].
We tried two options to fix the regression:
1) Increase the threshold to trigger the slowpath in lruvec stats
update codepath from 32 to 512.
2) Remove the slowpath from lruvec stats update codepath and instead
flush the stats in the page refault codepath. The assumption is that
the kernel timely flush the stats, so, the update tree would be
small in the refault codepath to not cause the preformance impact.
Following are the results of will-it-scale/page_fault[1|2|3] benchmark
on four settings i.e. (1) 5.15-rc1 as baseline (2) 5.15-rc1 with
aa48e47e39 and 7e1c0d6f58 reverted (3) 5.15-rc1 with option-1
(4) 5.15-rc1 with option-2.
test (1) (2) (3) (4)
pg_f1 368563 406277 (10.23%) 399693 (8.44%) 416398 (12.97%)
pg_f2 338399 372133 (9.96%) 369180 (9.09%) 381024 (12.59%)
pg_f3 500853 575399 (14.88%) 570388 (13.88%) 576083 (15.02%)
From the above result, it seems like the option-2 not only solves the
regression but also improves the performance for at least these
benchmarks.
Feng Tang (intel) ran the aim7 benchmark with these two options and
confirms that option-1 reduces the regression but option-2 removes the
regression.
Michael Larabel (phoronix) ran multiple benchmarks with these options
and reported the results at [3] and it shows for most benchmarks
option-2 removes the regression introduced by the commit aa48e47e39
("memcg: infrastructure to flush memcg stats").
Based on the experiment results, this patch proposed the option-2 as the
solution to resolve the regression.
Link: https://lore.kernel.org/all/20210726022421.GB21872@xsang-OptiPlex-9020 [1]
Link: https://www.phoronix.com/scan.php?page=article&item=linux515-compile-regress [2]
Link: https://openbenchmarking.org/result/2109226-DEBU-LINUX5104 [3]
Fixes: aa48e47e39 ("memcg: infrastructure to flush memcg stats")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Tested-by: Michael Larabel <Michael@phoronix.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hillf Danton <hdanton@sina.com>,
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
UAPI Changes:
Cross-subsystem Changes:
- dma-buf: Avoid a warning with some allocations, Remove
DMA_FENCE_TRACE macros
Core Changes:
- bridge: New helper to git rid of panels in drivers
- fence: Improve dma_fence_add_callback documentation, Improve
dma_fence_ops->wait documentation
- ioctl: Unexport drm_ioctl_permit
- lease: Documentation improvements
- fourcc: Add new macro to determine the modifier vendor
- quirks: Add the Steam Deck, Chuwi HiBook, Chuwi Hi10 Pro, Samsung
Galaxy Book 10.6, KD Kurio Smart C15200 2-in-1, Lenovo Ideapad D330
- resv: Improve the documentation
- shmem-helpers: Allocate WC pages on x86, Switch to vmf_insert_pfn
- sched: Fix for a timer being canceled too soon, Avoid null pointer
derefence if the fence is null in drm_sched_fence_free, Convert
drivers to rely on its dependency tracking
- ttm: Switch to kerneldoc, new helper to clear all DMA mappings, pool
shrinker optitimization, Remove ttm_tt_destroy_common, Fix for
unbinding on multiple drivers
Driver Changes:
- bochs: New PCI IDs
- msm: Fence ordering impromevemnts
- stm: Add layer alpha support, zpos
- v3d: Fix for a Vulkan CTS failure
- vc4: Conversion to the new bridge helpers
- vgem: Use shmem helpers
- virtio: Support mapping exported vram
- zte: Remove obsolete driver
- bridge: Probe improvements for it66121, enable DSI EOTP for anx7625,
errors propagation improvements for anx7625
- panels: 60fps mode for otm8009a, New driver for Samsung S6D27A1
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Merge tag 'drm-misc-next-2021-09-16' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
drm-misc-next for $kernel-version:
UAPI Changes:
Cross-subsystem Changes:
- dma-buf: Avoid a warning with some allocations, Remove
DMA_FENCE_TRACE macros
Core Changes:
- bridge: New helper to git rid of panels in drivers
- fence: Improve dma_fence_add_callback documentation, Improve
dma_fence_ops->wait documentation
- ioctl: Unexport drm_ioctl_permit
- lease: Documentation improvements
- fourcc: Add new macro to determine the modifier vendor
- quirks: Add the Steam Deck, Chuwi HiBook, Chuwi Hi10 Pro, Samsung
Galaxy Book 10.6, KD Kurio Smart C15200 2-in-1, Lenovo Ideapad D330
- resv: Improve the documentation
- shmem-helpers: Allocate WC pages on x86, Switch to vmf_insert_pfn
- sched: Fix for a timer being canceled too soon, Avoid null pointer
derefence if the fence is null in drm_sched_fence_free, Convert
drivers to rely on its dependency tracking
- ttm: Switch to kerneldoc, new helper to clear all DMA mappings, pool
shrinker optitimization, Remove ttm_tt_destroy_common, Fix for
unbinding on multiple drivers
Driver Changes:
- bochs: New PCI IDs
- msm: Fence ordering impromevemnts
- stm: Add layer alpha support, zpos
- v3d: Fix for a Vulkan CTS failure
- vc4: Conversion to the new bridge helpers
- vgem: Use shmem helpers
- virtio: Support mapping exported vram
- zte: Remove obsolete driver
- bridge: Probe improvements for it66121, enable DSI EOTP for anx7625,
errors propagation improvements for anx7625
- panels: 60fps mode for otm8009a, New driver for Samsung S6D27A1
Signed-off-by: Dave Airlie <airlied@redhat.com>
# gpg: Signature made Thu 16 Sep 2021 17:30:50 AEST
# gpg: using EDDSA key 5C1337A45ECA9AEB89060E9EE3EF0D6F671851C5
# gpg: Can't check signature: No public key
From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210916073132.ptbbmjetm7v3ufq3@gilmour
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Merge tag 'afs-fixes-20210913' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS fixes from David Howells:
"Fixes for AFS problems that can cause data corruption due to
interaction with another client modifying data cached locally:
- When d_revalidating a dentry, don't look at the inode to which it
points. Only check the directory to which the dentry belongs. This
was confusing things and causing the silly-rename cleanup code to
remove the file now at the dentry of a file that got deleted.
- Fix mmap data coherency. When a callback break is received that
relates to a file that we have cached, the data content may have
been changed (there are other reasons, such as the user's rights
having been changed). However, we're checking it lazily, only on
entry to the kernel, which doesn't happen if we have a writeable
shared mapped page on that file.
We make the kernel keep track of mmapped files and clear all PTEs
mapping to that file as soon as the callback comes in by calling
unmap_mapping_pages() (we don't necessarily want to zap the
pagecache). This causes the kernel to be reentered when userspace
tries to access the mmapped address range again - and at that point
we can query the server and, if we need to, zap the page cache.
Ideally, I would check each file at the point of notification, but
that involves poking the server[*] - which is holding an exclusive
lock on the vnode it is changing, waiting for all the clients it
notified to reply. This could then deadlock against the server.
Further, invalidating the pagecache might call ->launder_page(),
which would try to write to the file, which would definitely
deadlock. (AFS doesn't lease file access).
[*] Checking to see if the file content has changed is a matter of
comparing the current data version number, but we have to ask
the server for that. We also need to get a new callback promise
and we need to poke the server for that too.
- Add some more points at which the inode is validated, since we're
doing it lazily, notably in ->read_iter() and ->page_mkwrite(), but
also when performing some directory operations.
Ideally, checking in ->read_iter() would be done in some derivation
of filemap_read(). If we're going to call the server to read the
file, then we get the file status fetch as part of that.
- The above is now causing us to make a lot more calls to
afs_validate() to check the inode - and afs_validate() takes the
RCU read lock each time to make a quick check (ie.
afs_check_validity()). This is entirely for the purpose of checking
cb_s_break to see if the server we're using reinitialised its list
of callbacks - however this isn't a very common event, so most of
the time we're taking this needlessly.
Add a new cell-wide counter to count the number of
reinitialisations done by any server and check that - and only if
that changes, take the RCU read lock and check the server list (the
server list may change, but the cell a file is part of won't).
- Don't update vnode->cb_s_break and ->cb_v_break inside the validity
checking loop. The cb_lock is done with read_seqretry, so we might
go round the loop a second time after resetting those values - and
that could cause someone else checking validity to miss something
(I think).
Also included are patches for fixes for some bugs encountered whilst
debugging this:
- Fix a leak of afs_read objects and fix a leak of keys hidden by
that.
- Fix a leak of pages that couldn't be added to extend a writeback.
- Fix the maintenance of i_blocks when i_size is changed by a local
write or a local dir edit"
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214217 [1]
Link: https://lore.kernel.org/r/163111665183.283156.17200205573146438918.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163113612442.352844.11162345591911691150.stgit@warthog.procyon.org.uk/ # i_blocks patch
* tag 'afs-fixes-20210913' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Fix updating of i_blocks on file/dir extension
afs: Fix corruption in reads at fpos 2G-4G from an OpenAFS server
afs: Try to avoid taking RCU read lock when checking vnode validity
afs: Fix mmap coherency vs 3rd-party changes
afs: Fix incorrect triggering of sillyrename on 3rd-party invalidation
afs: Add missing vnode validation checks
afs: Fix page leak
afs: Fix missing put on afs_read objects and missing get on the key therein
The boot-time allocation interface for memblock is a mess, with
'memblock_alloc()' returning a virtual pointer, but then you are
supposed to free it with 'memblock_free()' that takes a _physical_
address.
Not only is that all kinds of strange and illogical, but it actually
causes bugs, when people then use it like a normal allocation function,
and it fails spectacularly on a NULL pointer:
https://lore.kernel.org/all/20210912140820.GD25450@xsang-OptiPlex-9020/
or just random memory corruption if the debug checks don't catch it:
https://lore.kernel.org/all/61ab2d0c-3313-aaab-514c-e15b7aa054a0@suse.cz/
I really don't want to apply patches that treat the symptoms, when the
fundamental cause is this horribly confusing interface.
I started out looking at just automating a sane replacement sequence,
but because of this mix or virtual and physical addresses, and because
people have used the "__pa()" macro that can take either a regular
kernel pointer, or just the raw "unsigned long" address, it's all quite
messy.
So this just introduces a new saner interface for freeing a virtual
address that was allocated using 'memblock_alloc()', and that was kept
as a regular kernel pointer. And then it converts a couple of users
that are obvious and easy to test, including the 'xbc_nodes' case in
lib/bootconfig.c that caused problems.
Reported-by: kernel test robot <oliver.sang@intel.com>
Fixes: 40caa127f3 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge patch series from Nick Desaulniers to update the minimum gcc
version to 5.1.
This is some of the left-overs from the merge window that I didn't want
to deal with yesterday, so it comes in after -rc1 but was sent before.
Gcc-4.9 support has been an annoyance for some time, and with -Werror I
had the choice of applying a fairly big patch from Kees Cook to remove a
fair number of initializer warnings (still leaving some), or this patch
series from Nick that just removes the source of the problem.
The initializer cleanups might still be worth it regardless, but
honestly, I preferred just tackling the problem with gcc-4.9 head-on.
We've been more aggressiuve about no longer having to care about
compilers that were released a long time ago, and I think it's been a
good thing.
I added a couple of patches on top to sort out a few left-overs now that
we no longer support gcc-4.x.
As noted by Arnd, as a result of this minimum compiler version upgrade
we can probably change our use of '--std=gnu89' to '--std=gnu11', and
finally start using local loop declarations etc. But this series does
_not_ yet do that.
Link: https://lore.kernel.org/all/20210909182525.372ee687@canb.auug.org.au/
Link: https://lore.kernel.org/lkml/CAK7LNASs6dvU6D3jL2GG3jW58fXfaj6VNOe55NJnTB8UPuk2pA@mail.gmail.com/
Link: https://github.com/ClangBuiltLinux/linux/issues/1438
* emailed patches from Nick Desaulniers <ndesaulniers@google.com>:
Drop some straggling mentions of gcc-4.9 as being stale
compiler_attributes.h: drop __has_attribute() support for gcc4
vmlinux.lds.h: remove old check for GCC 4.9
compiler-gcc.h: drop checks for older GCC versions
Makefile: drop GCC < 5 -fno-var-tracking-assignments workaround
arm64: remove GCC version check for ARCH_SUPPORTS_INT128
powerpc: remove GCC version check for UPD_CONSTR
riscv: remove Kconfig check for GCC version for ARCH_RV64I
Kconfig.debug: drop GCC 5+ version check for DWARF5
mm/ksm: remove old GCC 4.9+ check
compiler.h: drop fallback overflow checkers
Documentation: raise minimum supported version of GCC to 5.1
The minimum supported version of GCC has been raised to GCC 5.1.
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix the coherency management of mmap'd data such that 3rd-party changes
become visible as soon as possible after the callback notification is
delivered by the fileserver. This is done by the following means:
(1) When we break a callback on a vnode specified by the CB.CallBack call
from the server, we queue a work item (vnode->cb_work) to go and
clobber all the PTEs mapping to that inode.
This causes the CPU to trip through the ->map_pages() and
->page_mkwrite() handlers if userspace attempts to access the page(s)
again.
(Ideally, this would be done in the service handler for CB.CallBack,
but the server is waiting for our reply before considering, and we
have a list of vnodes, all of which need breaking - and the process of
getting the mmap_lock and stripping the PTEs on all CPUs could be
quite slow.)
(2) Call afs_validate() from the ->map_pages() handler to check to see if
the file has changed and to get a new callback promise from the
server.
Also handle the fileserver telling us that it's dropping all callbacks,
possibly after it's been restarted by sending us a CB.InitCallBackState*
call by the following means:
(3) Maintain a per-cell list of afs files that are currently mmap'd
(cell->fs_open_mmaps).
(4) Add a work item to each server that is invoked if there are any open
mmaps when CB.InitCallBackState happens. This work item goes through
the aforementioned list and invokes the vnode->cb_work work item for
each one that is currently using this server.
This causes the PTEs to be cleared, causing ->map_pages() or
->page_mkwrite() to be called again, thereby calling afs_validate()
again.
I've chosen to simply strip the PTEs at the point of notification reception
rather than invalidate all the pages as well because (a) it's faster, (b)
we may get a notification for other reasons than the data being altered (in
which case we don't want to clobber the pagecache) and (c) we need to ask
the server to find out - and I don't want to wait for the reply before
holding up userspace.
This was tested using the attached test program:
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
int main(int argc, char *argv[])
{
size_t size = getpagesize();
unsigned char *p;
bool mod = (argc == 3);
int fd;
if (argc != 2 && argc != 3) {
fprintf(stderr, "Format: %s <file> [mod]\n", argv[0]);
exit(2);
}
fd = open(argv[1], mod ? O_RDWR : O_RDONLY);
if (fd < 0) {
perror(argv[1]);
exit(1);
}
p = mmap(NULL, size, mod ? PROT_READ|PROT_WRITE : PROT_READ,
MAP_SHARED, fd, 0);
if (p == MAP_FAILED) {
perror("mmap");
exit(1);
}
for (;;) {
if (mod) {
p[0]++;
msync(p, size, MS_ASYNC);
fsync(fd);
}
printf("%02x", p[0]);
fflush(stdout);
sleep(1);
}
}
It runs in two modes: in one mode, it mmaps a file, then sits in a loop
reading the first byte, printing it and sleeping for a second; in the
second mode it mmaps a file, then sits in a loop incrementing the first
byte and flushing, then printing and sleeping.
Two instances of this program can be run on different machines, one doing
the reading and one doing the writing. The reader should see the changes
made by the writer, but without this patch, they aren't because validity
checking is being done lazily - only on entry to the filesystem.
Testing the InitCallBackState change is more complicated. The server has
to be taken offline, the saved callback state file removed and then the
server restarted whilst the reading-mode program continues to run. The
client machine then has to poke the server to trigger the InitCallBackState
call.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/163111668833.283156.382633263709075739.stgit@warthog.procyon.org.uk/
Merge yet more updates and hotfixes from Andrew Morton:
"Post-linux-next material, based upon latest upstream to catch the
now-merged dependencies:
- 10 patches.
Subsystems affected by this patch series: mm (vmstat and migration)
and compat.
And bunch of hotfixes, mostly cc:stable:
- 8 patches.
Subsystems affected by this patch series: mm (hmm, hugetlb, vmscan,
pagealloc, pagemap, kmemleak, mempolicy, and memblock)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
arch: remove compat_alloc_user_space
compat: remove some compat entry points
mm: simplify compat numa syscalls
mm: simplify compat_sys_move_pages
kexec: avoid compat_alloc_user_space
kexec: move locking into do_kexec_load
mm: migrate: change to use bool type for 'page_was_mapped'
mm: migrate: fix the incorrect function name in comments
mm: migrate: introduce a local variable to get the number of pages
mm/vmstat: protect per cpu variables with preempt disable on RT
* emailed hotfixes from Andrew Morton <akpm@linux-foundation.org>:
nds32/setup: remove unused memblock_region variable in setup_memory()
mm/mempolicy: fix a race between offset_il_node and mpol_rebind_task
mm/kmemleak: allow __GFP_NOLOCKDEP passed to kmemleak's gfp
mmap_lock: change trace and locking order
mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype
mm,vmscan: fix divide by zero in get_scan_count
mm/hugetlb: initialize hugetlb_usage in mm_init
mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled
Servers happened below panic:
Kernel version:5.4.56
BUG: unable to handle page fault for address: 0000000000002c48
RIP: 0010:__next_zones_zonelist+0x1d/0x40
Call Trace:
__alloc_pages_nodemask+0x277/0x310
alloc_page_interleave+0x13/0x70
handle_mm_fault+0xf99/0x1390
__do_page_fault+0x288/0x500
do_page_fault+0x30/0x110
page_fault+0x3e/0x50
The reason for the panic is that MAX_NUMNODES is passed in the third
parameter in __alloc_pages_nodemask(preferred_nid). So access to
zonelist->zoneref->zone_idx in __next_zones_zonelist will cause a panic.
In offset_il_node(), first_node() returns nid from pol->v.nodes, after
this other threads may chang pol->v.nodes before next_node(). This race
condition will let next_node return MAX_NUMNODES. So put pol->nodes in
a local variable.
The race condition is between offset_il_node and cpuset_change_task_nodemask:
CPU0: CPU1:
alloc_pages_vma()
interleave_nid(pol,)
offset_il_node(pol,)
first_node(pol->v.nodes) cpuset_change_task_nodemask
//nodes==0xc mpol_rebind_task
mpol_rebind_policy
mpol_rebind_nodemask(pol,nodes)
//nodes==0x3
next_node(nid, pol->v.nodes)//return MAX_NUMNODES
Link: https://lkml.kernel.org/r/20210906034658.48721-1-yanghui.def@bytedance.com
Signed-off-by: yanghui <yanghui.def@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In a memory pressure situation, I'm seeing the lockdep WARNING below.
Actually, this is similar to a known false positive which is already
addressed by commit 6dcde60efd ("xfs: more lockdep whackamole with
kmem_alloc*").
This warning still persists because it's not from kmalloc() itself but
from an allocation for kmemleak object. While kmalloc() itself suppress
the warning with __GFP_NOLOCKDEP, gfp_kmemleak_mask() is dropping the
flag for the kmemleak's allocation.
Allow __GFP_NOLOCKDEP to be passed to kmemleak's allocation, so that the
warning for it is also suppressed.
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc7-BTRFS-ZNS+ #37 Not tainted
------------------------------------------------------
kswapd0/288 is trying to acquire lock:
ffff88825ab45df0 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x8a/0x250
but task is already holding lock:
ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (fs_reclaim){+.+.}-{0:0}:
fs_reclaim_acquire+0x112/0x160
kmem_cache_alloc+0x48/0x400
create_object.isra.0+0x42/0xb10
kmemleak_alloc+0x48/0x80
__kmalloc+0x228/0x440
kmem_alloc+0xd3/0x2b0
kmem_alloc_large+0x5a/0x1c0
xfs_attr_copy_value+0x112/0x190
xfs_attr_shortform_getvalue+0x1fc/0x300
xfs_attr_get_ilocked+0x125/0x170
xfs_attr_get+0x329/0x450
xfs_get_acl+0x18d/0x430
get_acl.part.0+0xb6/0x1e0
posix_acl_xattr_get+0x13a/0x230
vfs_getxattr+0x21d/0x270
getxattr+0x126/0x310
__x64_sys_fgetxattr+0x1a6/0x2a0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&xfs_nondir_ilock_class){++++}-{3:3}:
__lock_acquire+0x2c0f/0x5a00
lock_acquire+0x1a1/0x4b0
down_read_nested+0x50/0x90
xfs_ilock+0x8a/0x250
xfs_can_free_eofblocks+0x34f/0x570
xfs_inactive+0x411/0x520
xfs_fs_destroy_inode+0x2c8/0x710
destroy_inode+0xc5/0x1a0
evict+0x444/0x620
dispose_list+0xfe/0x1c0
prune_icache_sb+0xdc/0x160
super_cache_scan+0x31e/0x510
do_shrink_slab+0x337/0x8e0
shrink_slab+0x362/0x5c0
shrink_node+0x7a7/0x1a40
balance_pgdat+0x64e/0xfe0
kswapd+0x590/0xa80
kthread+0x38c/0x460
ret_from_fork+0x22/0x30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&xfs_nondir_ilock_class);
lock(fs_reclaim);
lock(&xfs_nondir_ilock_class);
*** DEADLOCK ***
3 locks held by kswapd0/288:
#0: ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
#1: ffffffff848a08d8 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x269/0x5c0
#2: ffff8881a7a820e8 (&type->s_umount_key#60){++++}-{3:3}, at: super_cache_scan+0x5a/0x510
Link: https://lkml.kernel.org/r/20210907055659.3182992-1-naohiro.aota@wdc.com
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If it's not prepared to free unref page, the pcp page migratetype is
unset. Thus we will get rubbish from get_pcppage_migratetype() and
might list_del(&page->lru) again after it's already deleted from the list
leading to grumble about data corruption.
Link: https://lkml.kernel.org/r/20210902115447.57050-1-linmiaohe@huawei.com
Fixes: df1acc8569 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit f56ce412a5 ("mm: memcontrol: fix occasional OOMs due to
proportional memory.low reclaim") introduced a divide by zero corner
case when oomd is being used in combination with cgroup memory.low
protection.
When oomd decides to kill a cgroup, it will force the cgroup memory to
be reclaimed after killing the tasks, by writing to the memory.max file
for that cgroup, forcing the remaining page cache and reclaimable slab
to be reclaimed down to zero.
Previously, on cgroups with some memory.low protection that would result
in the memory being reclaimed down to the memory.low limit, or likely
not at all, having the page cache reclaimed asynchronously later.
With f56ce412a5 the oomd write to memory.max tries to reclaim all the
way down to zero, which may race with another reclaimer, to the point of
ending up with the divide by zero below.
This patch implements the obvious fix.
Link: https://lkml.kernel.org/r/20210826220149.058089c6@imladris.surriel.com
Fixes: f56ce412a5 ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim")
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously, we noticed the one rpma example was failed[1] since commit
36f30e486d ("IB/core: Improve ODP to use hmm_range_fault()"), where it
will use ODP feature to do RDMA WRITE between fsdax files.
After digging into the code, we found hmm_vma_handle_pte() will still
return EFAULT even though all the its requesting flags has been
fulfilled. That's because a DAX page will be marked as (_PAGE_SPECIAL |
PAGE_DEVMAP) by pte_mkdevmap().
Link: https://github.com/pmem/rpma/issues/1142 [1]
Link: https://lkml.kernel.org/r/20210830094232.203029-1-lizhijian@cn.fujitsu.com
Fixes: 4055062749 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling")
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These are all handled correctly when calling the native system call entry
point, so remove the special cases.
Link: https://lkml.kernel.org/r/20210727144859.4150043-6-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The compat implementations for mbind, get_mempolicy, set_mempolicy and
migrate_pages are just there to handle the subtly different layout of
bitmaps on 32-bit hosts.
The compat implementation however lacks some of the checks that are
present in the native one, in particular for checking that the extra bits
are all zero when user space has a larger mask size than the kernel.
Worse, those extra bits do not get cleared when copying in or out of the
kernel, which can lead to incorrect data as well.
Unify the implementation to handle the compat bitmap layout directly in
the get_nodes() and copy_nodes_to_user() helpers. Splitting out the
get_bitmap() helper from get_nodes() also helps readability of the native
case.
On x86, two additional problems are addressed by this: compat tasks can
pass a bitmap at the end of a mapping, causing a fault when reading across
the page boundary for a 64-bit word. x32 tasks might also run into
problems with get_mempolicy corrupting data when an odd number of 32-bit
words gets passed.
On parisc the migrate_pages() system call apparently had the wrong calling
convention, as big-endian architectures expect the words inside of a
bitmap to be swapped. This is not a problem though since parisc has no
NUMA support.
[arnd@arndb.de: fix mempolicy crash]
Link: https://lkml.kernel.org/r/20210730143417.3700653-1-arnd@kernel.org
Link: https://lore.kernel.org/lkml/YQPLG20V3dmOfq3a@osiris/
Link: https://lkml.kernel.org/r/20210727144859.4150043-5-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The compat move_pages() implementation uses compat_alloc_user_space() for
converting the pointer array. Moving the compat handling into the
function itself is a bit simpler and lets us avoid the
compat_alloc_user_space() call.
Link: https://lkml.kernel.org/r/20210727144859.4150043-4-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change to use bool type for 'page_was_mapped' variable making it more
readable.
Link: https://lkml.kernel.org/r/ce1279df18d2c163998c403e0b5ec6d3f6f90f7a.1629447552.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
since commit a98a2f0c8c ("mm/rmap: split migration into its own
function"), the migration ptes establishment has been split into a
separate try_to_migrate() function, thus update the related comments.
Link: https://lkml.kernel.org/r/5b824bad6183259c916ae6cf42f81d14c6118b06.1629447552.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use thp_nr_pages() instead of compound_nr() to get the number of pages for
THP page, meanwhile introducing a local variable 'nr_pages' to avoid
getting the number of pages repeatedly.
Link: https://lkml.kernel.org/r/a8e331ac04392ee230c79186330fb05e86a2aa77.1629447552.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Disable preemption on -RT for the vmstat code. On vanila the code runs in
IRQ-off regions while on -RT it may not when stats are updated under a
local_lock. "preempt_disable" ensures that the same resources is not
updated in parallel due to preemption.
This patch differs from the preempt-rt version where __count_vm_event and
__count_vm_events are also protected. The counters are explicitly
"allowed to be to be racy" so there is no need to protect them from
preemption. Only the accurate page stats that are updated by a
read-modify-write need protection. This patch also differs in that a
preempt_[en|dis]able_rt helper is not used. As vmstat is the only user of
the helper, it was suggested that it be open-coded in vmstat.c instead of
risking the helper being used in unnecessary contexts.
Link: https://lkml.kernel.org/r/20210805160019.1137-2-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge more updates from Andrew Morton:
"147 patches, based on 7d2a07b769.
Subsystems affected by this patch series: mm (memory-hotplug, rmap,
ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
selftests, ipc, and scripts"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
scripts: check_extable: fix typo in user error message
mm/workingset: correct kernel-doc notations
ipc: replace costly bailout check in sysvipc_find_ipc()
selftests/memfd: remove unused variable
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
configs: remove the obsolete CONFIG_INPUT_POLLDEV
prctl: allow to setup brk for et_dyn executables
pid: cleanup the stale comment mentioning pidmap_init().
kernel/fork.c: unexport get_{mm,task}_exe_file
coredump: fix memleak in dump_vma_snapshot()
fs/coredump.c: log if a core dump is aborted due to changed file permissions
nilfs2: use refcount_dec_and_lock() to fix potential UAF
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
trap: cleanup trap_init()
init: move usermodehelper_enable() to populate_rootfs()
...
This series was initially inspired by Mel's pcplist local_lock rewrite, and
also interest to better understand SLUB's locking and the new primitives and RT
variants and implications. It makes SLUB compatible with PREEMPT_RT and
generally more preemption-friendly, apparently without significant regressions,
as the fast paths are not affected.
The main changes to SLUB by this series:
* irq disabling is now only done for minimum amount of time needed to protect
the strict kmem_cache_cpu fields, and as part of spin lock, local lock and
bit lock operations to make them irq-safe
* SLUB is fully PREEMPT_RT compatible
Series is based on 5.14-rc6 and also available as a git branch:
https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git/log/?h=slub-local-lock-v5r0
The series should now be sufficiently tested in both RT and !RT configs, mainly
thanks to Mike.
The RFC/v1 version also got basic performance screening by Mel that didn't show
major regressions. Mike's testing with hackbench of v2 on !RT reported
negligible differences [6]:
virgin(ish) tip
5.13.0.g60ab3ed-tip
7,320.67 msec task-clock # 7.792 CPUs utilized ( +- 0.31% )
221,215 context-switches # 0.030 M/sec ( +- 3.97% )
16,234 cpu-migrations # 0.002 M/sec ( +- 4.07% )
13,233 page-faults # 0.002 M/sec ( +- 0.91% )
27,592,205,252 cycles # 3.769 GHz ( +- 0.32% )
8,309,495,040 instructions # 0.30 insn per cycle ( +- 0.37% )
1,555,210,607 branches # 212.441 M/sec ( +- 0.42% )
5,484,209 branch-misses # 0.35% of all branches ( +- 2.13% )
0.93949 +- 0.00423 seconds time elapsed ( +- 0.45% )
0.94608 +- 0.00384 seconds time elapsed ( +- 0.41% ) (repeat)
0.94422 +- 0.00410 seconds time elapsed ( +- 0.43% )
5.13.0.g60ab3ed-tip +slub-local-lock-v2r3
7,343.57 msec task-clock # 7.776 CPUs utilized ( +- 0.44% )
223,044 context-switches # 0.030 M/sec ( +- 3.02% )
16,057 cpu-migrations # 0.002 M/sec ( +- 4.03% )
13,164 page-faults # 0.002 M/sec ( +- 0.97% )
27,684,906,017 cycles # 3.770 GHz ( +- 0.45% )
8,323,273,871 instructions # 0.30 insn per cycle ( +- 0.28% )
1,556,106,680 branches # 211.901 M/sec ( +- 0.31% )
5,463,468 branch-misses # 0.35% of all branches ( +- 1.33% )
0.94440 +- 0.00352 seconds time elapsed ( +- 0.37% )
0.94830 +- 0.00228 seconds time elapsed ( +- 0.24% ) (repeat)
0.93813 +- 0.00440 seconds time elapsed ( +- 0.47% ) (repeat)
RT configs showed some throughput regressions, but that's expected tradeoff for
the preemption improvements through the RT mutex. It didn't prevent the v2 to
be incorporated to the 5.13 RT tree [7], leading to testing exposure and
bugfixes.
Before the series, SLUB is lockless in both allocation and free fast paths, but
elsewhere, it's disabling irqs for considerable periods of time - especially in
allocation slowpath and the bulk allocation, where IRQs are re-enabled only
when a new page from the page allocator is needed, and the context allows
blocking. The irq disabled sections can then include deactivate_slab() which
walks a full freelist and frees the slab back to page allocator or
unfreeze_partials() going through a list of percpu partial slabs. The RT tree
currently has some patches mitigating these, but we can do much better in
mainline too.
Patches 1-6 are straightforward improvements or cleanups that could exist
outside of this series too, but are prerequsities.
Patches 7-9 are also preparatory code changes without functional changes, but
not so useful without the rest of the series.
Patch 10 simplifies the fast paths on systems with preemption, based on
(hopefully correct) observation that the current loops to verify tid are
unnecessary.
Patches 11-20 focus on reducing irq disabled scope in the allocation slowpath.
Patch 11 moves disabling of irqs into ___slab_alloc() from its callers, which
are the allocation slowpath, and bulk allocation. Instead these callers only
disable preemption to stabilize the cpu. The following patches then gradually
reduce the scope of disabled irqs in ___slab_alloc() and the functions called
from there. As of patch 14, the re-enabling of irqs based on gfp flags before
calling the page allocator is removed from allocate_slab(). As of patch 17,
it's possible to reach the page allocator (in case of existing slabs depleted)
without disabling and re-enabling irqs a single time.
Pathces 21-26 reduce the scope of disabled irqs in functions related to
unfreezing percpu partial slab.
Patch 27 is preparatory. Patch 28 is adopted from the RT tree and converts the
flushing of percpu slabs on all cpus from using IPI to workqueue, so that the
processing isn't happening with irqs disabled in the IPI handler. The flushing
is not performance critical so it should be acceptable.
Patch 29 also comes from RT tree and makes object_map_lock RT compatible.
Patch 30 make slab_lock irq-safe on RT where we cannot rely on having
irq disabled from the list_lock spin lock usage.
Patch 31 changes kmem_cache_cpu->partial handling in put_cpu_partial() from
cmpxchg loop to a short irq disabled section, which is used by all other code
modifying the field. This addresses a theoretical race scenario pointed out by
Jann, and makes the critical section safe wrt with RT local_lock semantics
after the conversion in patch 35.
Patch 32 changes preempt disable to migrate disable, so that the nested
list_lock spinlock is safe to take on RT. Because migrate_disable() is a
function call even on !RT, a small set of private wrappers is introduced
to keep using the cheaper preempt_disable() on !PREEMPT_RT configurations.
As of this patch, SLUB should be already compatible with RT's lock semantics.
Finally, patch 33 changes irq disabled sections that protect kmem_cache_cpu
fields in the slow paths, with a local lock. However on PREEMPT_RT it means the
lockless fast paths can now preempt slow paths which don't expect that, so the
local lock has to be taken also in the fast paths and they are no longer
lockless. RT folks seem to not mind this tradeoff. The patch also updates the
locking documentation in the file's comment.
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Merge tag 'mm-slub-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux
Pull SLUB updates from Vlastimil Babka:
"SLUB: reduce irq disabled scope and make it RT compatible
This series was initially inspired by Mel's pcplist local_lock
rewrite, and also interest to better understand SLUB's locking and the
new primitives and RT variants and implications. It makes SLUB
compatible with PREEMPT_RT and generally more preemption-friendly,
apparently without significant regressions, as the fast paths are not
affected.
The main changes to SLUB by this series:
- irq disabling is now only done for minimum amount of time needed to
protect the strict kmem_cache_cpu fields, and as part of spin lock,
local lock and bit lock operations to make them irq-safe
- SLUB is fully PREEMPT_RT compatible
The series should now be sufficiently tested in both RT and !RT
configs, mainly thanks to Mike.
The RFC/v1 version also got basic performance screening by Mel that
didn't show major regressions. Mike's testing with hackbench of v2 on
!RT reported negligible differences [6]:
virgin(ish) tip
5.13.0.g60ab3ed-tip
7,320.67 msec task-clock # 7.792 CPUs utilized ( +- 0.31% )
221,215 context-switches # 0.030 M/sec ( +- 3.97% )
16,234 cpu-migrations # 0.002 M/sec ( +- 4.07% )
13,233 page-faults # 0.002 M/sec ( +- 0.91% )
27,592,205,252 cycles # 3.769 GHz ( +- 0.32% )
8,309,495,040 instructions # 0.30 insn per cycle ( +- 0.37% )
1,555,210,607 branches # 212.441 M/sec ( +- 0.42% )
5,484,209 branch-misses # 0.35% of all branches ( +- 2.13% )
0.93949 +- 0.00423 seconds time elapsed ( +- 0.45% )
0.94608 +- 0.00384 seconds time elapsed ( +- 0.41% ) (repeat)
0.94422 +- 0.00410 seconds time elapsed ( +- 0.43% )
5.13.0.g60ab3ed-tip +slub-local-lock-v2r3
7,343.57 msec task-clock # 7.776 CPUs utilized ( +- 0.44% )
223,044 context-switches # 0.030 M/sec ( +- 3.02% )
16,057 cpu-migrations # 0.002 M/sec ( +- 4.03% )
13,164 page-faults # 0.002 M/sec ( +- 0.97% )
27,684,906,017 cycles # 3.770 GHz ( +- 0.45% )
8,323,273,871 instructions # 0.30 insn per cycle ( +- 0.28% )
1,556,106,680 branches # 211.901 M/sec ( +- 0.31% )
5,463,468 branch-misses # 0.35% of all branches ( +- 1.33% )
0.94440 +- 0.00352 seconds time elapsed ( +- 0.37% )
0.94830 +- 0.00228 seconds time elapsed ( +- 0.24% ) (repeat)
0.93813 +- 0.00440 seconds time elapsed ( +- 0.47% ) (repeat)
RT configs showed some throughput regressions, but that's expected
tradeoff for the preemption improvements through the RT mutex. It
didn't prevent the v2 to be incorporated to the 5.13 RT tree [7],
leading to testing exposure and bugfixes.
Before the series, SLUB is lockless in both allocation and free fast
paths, but elsewhere, it's disabling irqs for considerable periods of
time - especially in allocation slowpath and the bulk allocation,
where IRQs are re-enabled only when a new page from the page allocator
is needed, and the context allows blocking. The irq disabled sections
can then include deactivate_slab() which walks a full freelist and
frees the slab back to page allocator or unfreeze_partials() going
through a list of percpu partial slabs. The RT tree currently has some
patches mitigating these, but we can do much better in mainline too.
Patches 1-6 are straightforward improvements or cleanups that could
exist outside of this series too, but are prerequsities.
Patches 7-9 are also preparatory code changes without functional
changes, but not so useful without the rest of the series.
Patch 10 simplifies the fast paths on systems with preemption, based
on (hopefully correct) observation that the current loops to verify
tid are unnecessary.
Patches 11-20 focus on reducing irq disabled scope in the allocation
slowpath:
- patch 11 moves disabling of irqs into ___slab_alloc() from its
callers, which are the allocation slowpath, and bulk allocation.
Instead these callers only disable preemption to stabilize the cpu.
- The following patches then gradually reduce the scope of disabled
irqs in ___slab_alloc() and the functions called from there. As of
patch 14, the re-enabling of irqs based on gfp flags before calling
the page allocator is removed from allocate_slab(). As of patch 17,
it's possible to reach the page allocator (in case of existing
slabs depleted) without disabling and re-enabling irqs a single
time.
Pathces 21-26 reduce the scope of disabled irqs in functions related
to unfreezing percpu partial slab.
Patch 27 is preparatory. Patch 28 is adopted from the RT tree and
converts the flushing of percpu slabs on all cpus from using IPI to
workqueue, so that the processing isn't happening with irqs disabled
in the IPI handler. The flushing is not performance critical so it
should be acceptable.
Patch 29 also comes from RT tree and makes object_map_lock RT
compatible.
Patch 30 make slab_lock irq-safe on RT where we cannot rely on having
irq disabled from the list_lock spin lock usage.
Patch 31 changes kmem_cache_cpu->partial handling in put_cpu_partial()
from cmpxchg loop to a short irq disabled section, which is used by
all other code modifying the field. This addresses a theoretical race
scenario pointed out by Jann, and makes the critical section safe wrt
with RT local_lock semantics after the conversion in patch 35.
Patch 32 changes preempt disable to migrate disable, so that the
nested list_lock spinlock is safe to take on RT. Because
migrate_disable() is a function call even on !RT, a small set of
private wrappers is introduced to keep using the cheaper
preempt_disable() on !PREEMPT_RT configurations. As of this patch,
SLUB should be already compatible with RT's lock semantics.
Finally, patch 33 changes irq disabled sections that protect
kmem_cache_cpu fields in the slow paths, with a local lock. However on
PREEMPT_RT it means the lockless fast paths can now preempt slow paths
which don't expect that, so the local lock has to be taken also in the
fast paths and they are no longer lockless. RT folks seem to not mind
this tradeoff. The patch also updates the locking documentation in the
file's comment"
Mike Galbraith and Mel Gorman verified that their earlier testing
observations still hold for the final series:
Link: https://lore.kernel.org/lkml/89ba4f783114520c167cc915ba949ad2c04d6790.camel@gmx.de/
Link: https://lore.kernel.org/lkml/20210907082010.GB3959@techsingularity.net/
* tag 'mm-slub-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux: (33 commits)
mm, slub: convert kmem_cpu_slab protection to local_lock
mm, slub: use migrate_disable() on PREEMPT_RT
mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg
mm, slub: make slab_lock() disable irqs with PREEMPT_RT
mm: slub: make object_map_lock a raw_spinlock_t
mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context
mm, slab: split out the cpu offline variant of flush_slab()
mm, slub: don't disable irqs in slub_cpu_dead()
mm, slub: only disable irq with spin_lock in __unfreeze_partials()
mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing
mm, slub: detach whole partial list at once in unfreeze_partials()
mm, slub: discard slabs in unfreeze_partials() without irqs disabled
mm, slub: move irq control into unfreeze_partials()
mm, slub: call deactivate_slab() without disabling irqs
mm, slub: make locking in deactivate_slab() irq-safe
mm, slub: move reset of c->page and freelist out of deactivate_slab()
mm, slub: stop disabling irqs around get_partial()
mm, slub: check new pages with restored irqs
mm, slub: validate slab from partial list or page allocator before making it cpu slab
mm, slub: restore irqs around calling new_slab()
...
Use the documented kernel-doc format to prevent kernel-doc warnings.
mm/workingset.c:256: warning: No description found for return value of 'workingset_eviction'
mm/workingset.c:285: warning: Function parameter or member 'folio' not described in 'workingset_refault'
mm/workingset.c:285: warning: Excess function parameter 'page' description in 'workingset_refault'
Link: https://lkml.kernel.org/r/20210808203153.10678-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is not needed by any modules, so remove the export.
Link: https://lkml.kernel.org/r/20210722185814.504541-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit adds kunit based unit tests for the core and the virtual
address spaces monitoring primitives of DAMON.
Link: https://lkml.kernel.org/r/20210716081449.22187-12-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Fernand Sieber <sieberf@amazon.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In some use cases, users would want to run multiple monitoring context.
For example, if a user wants a high precision monitoring and dedicating
multiple CPUs for the job is ok, because DAMON creates one monitoring
thread per one context, the user can split the monitoring target regions
into multiple small regions and create one context for each region. Or,
someone might want to simultaneously monitor different address spaces,
e.g., both virtual address space and physical address space.
The DAMON's API allows such usage, but 'damon-dbgfs' does not. Therefore,
only kernel space DAMON users can do multiple contexts monitoring.
This commit allows the user space DAMON users to use multiple contexts
monitoring by introducing two new 'damon-dbgfs' debugfs files,
'mk_context' and 'rm_context'. Users can create a new monitoring context
by writing the desired name of the new context to 'mk_context'. Then, a
new directory with the name and having the files for setting of the
context ('attrs', 'target_ids' and 'record') will be created under the
debugfs directory. Writing the name of the context to remove to
'rm_context' will remove the related context and directory.
Link: https://lkml.kernel.org/r/20210716081449.22187-10-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For CPU usage accounting, knowing pid of the monitoring thread could be
helpful. For example, users could use cpuaccount cgroups with the pid.
This commit therefore exports the pid of currently running monitoring
thread to the user space via 'kdamond_pid' file in the debugfs directory.
Link: https://lkml.kernel.org/r/20210716081449.22187-9-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
DAMON is designed to be used by kernel space code such as the memory
management subsystems, and therefore it provides only kernel space API.
That said, letting the user space control DAMON could provide some
benefits to them. For example, it will allow user space to analyze their
specific workloads and make their own special optimizations.
For such cases, this commit implements a simple DAMON application kernel
module, namely 'damon-dbgfs', which merely wraps the DAMON api and exports
those to the user space via the debugfs.
'damon-dbgfs' exports three files, ``attrs``, ``target_ids``, and
``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
----------
Users can read and write the ``sampling interval``, ``aggregation
interval``, ``regions update interval``, and min/max number of monitoring
target regions by reading from and writing to the ``attrs`` file. For
example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10,
1000 and check it again::
# cd <debugfs>/damon
# echo 5000 100000 1000000 10 1000 > attrs
# cat attrs
5000 100000 1000000 10 1000
Target IDs
----------
Some types of address spaces supports multiple monitoring target. For
example, the virtual memory address spaces monitoring can have multiple
processes as the monitoring targets. Users can set the targets by writing
relevant id values of the targets to, and get the ids of the current
targets by reading from the ``target_ids`` file. In case of the virtual
address spaces monitoring, the values should be pids of the monitoring
target processes. For example, below commands set processes having pids
42 and 4242 as the monitoring targets and check it again::
# cd <debugfs>/damon
# echo 42 4242 > target_ids
# cat target_ids
42 4242
Note that setting the target ids doesn't start the monitoring.
Turning On/Off
--------------
Setting the files as described above doesn't incur effect unless you
explicitly start the monitoring. You can start, stop, and check the
current status of the monitoring by writing to and reading from the
``monitor_on`` file. Writing ``on`` to the file starts the monitoring of
the targets with the attributes. Writing ``off`` to the file stops those.
DAMON also stops if every targets are invalidated (in case of the virtual
memory monitoring, target processes are invalidated when terminated).
Below example commands turn on, off, and check the status of DAMON::
# cd <debugfs>/damon
# echo on > monitor_on
# echo off > monitor_on
# cat monitor_on
off
Please note that you cannot write to the above-mentioned debugfs files
while the monitoring is turned on. If you write to the files while DAMON
is running, an error code such as ``-EBUSY`` will be returned.
[akpm@linux-foundation.org: remove unneeded "alloc failed" printks]
[akpm@linux-foundation.org: replace macro with static inline]
Link: https://lkml.kernel.org/r/20210716081449.22187-8-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit adds a tracepoint for DAMON. It traces the monitoring results
of each region for each aggregation interval. Using this, DAMON can
easily integrated with tracepoints supporting tools such as perf.
Link: https://lkml.kernel.org/r/20210716081449.22187-7-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit introduces a reference implementation of the address space
specific low level primitives for the virtual address space, so that users
of DAMON can easily monitor the data accesses on virtual address spaces of
specific processes by simply configuring the implementation to be used by
DAMON.
The low level primitives for the fundamental access monitoring are defined
in two parts:
1. Identification of the monitoring target address range for the address
space.
2. Access check of specific address range in the target space.
The reference implementation for the virtual address space does the works
as below.
PTE Accessed-bit Based Access Check
-----------------------------------
The implementation uses PTE Accessed-bit for basic access checks. That
is, it clears the bit for the next sampling target page and checks whether
it is set again after one sampling period. This could disturb the reclaim
logic. DAMON uses ``PG_idle`` and ``PG_young`` page flags to solve the
conflict, as Idle page tracking does.
VMA-based Target Address Range Construction
-------------------------------------------
Only small parts in the super-huge virtual address space of the processes
are mapped to physical memory and accessed. Thus, tracking the unmapped
address regions is just wasteful. However, because DAMON can deal with
some level of noise using the adaptive regions adjustment mechanism,
tracking every mapping is not strictly required but could even incur a
high overhead in some cases. That said, too huge unmapped areas inside
the monitoring target should be removed to not take the time for the
adaptive mechanism.
For the reason, this implementation converts the complex mappings to three
distinct regions that cover every mapped area of the address space. Also,
the two gaps between the three regions are the two biggest unmapped areas
in the given address space. The two biggest unmapped areas would be the
gap between the heap and the uppermost mmap()-ed region, and the gap
between the lowermost mmap()-ed region and the stack in most of the cases.
Because these gaps are exceptionally huge in usual address spaces,
excluding these will be sufficient to make a reasonable trade-off. Below
shows this in detail::
<heap>
<BIG UNMAPPED REGION 1>
<uppermost mmap()-ed region>
(small mmap()-ed regions and munmap()-ed regions)
<lowermost mmap()-ed region>
<BIG UNMAPPED REGION 2>
<stack>
[akpm@linux-foundation.org: mm/damon/vaddr.c needs highmem.h for kunmap_atomic()]
[sjpark@amazon.de: remove unnecessary PAGE_EXTENSION setup]
Link: https://lkml.kernel.org/r/20210806095153.6444-2-sj38.park@gmail.com
[sjpark@amazon.de: safely walk page table]
Link: https://lkml.kernel.org/r/20210831161800.29419-1-sj38.park@gmail.com
Link: https://lkml.kernel.org/r/20210716081449.22187-6-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page
Tracking and the reclaim logic concurrently work while not interfering
with each other. That is, when they need to clear the Accessed bit, they
set PG_young to represent the previous state of the bit, respectively.
And when they need to read the bit, if the bit is cleared, they further
read the PG_young to know whether the other has cleared the bit meanwhile
or not.
For yet another user of the PTE Accessed bit, we could add another page
flag, or extend the mechanism to use the flags. For the DAMON usecase,
however, we don't need to do that just yet. IDLE_PAGE_TRACKING and DAMON
are mutually exclusive, so there's only ever going to be one user of the
current set of flags.
In this commit, we split out the CONFIG options to allow for the use of
PG_young and PG_idle outside of idle page tracking.
In the next commit, DAMON's reference implementation of the virtual memory
address space monitoring primitives will use it.
[sjpark@amazon.de: set PAGE_EXTENSION for non-64BIT]
Link: https://lkml.kernel.org/r/20210806095153.6444-1-sj38.park@gmail.com
[akpm@linux-foundation.org: tweak Kconfig text]
[sjpark@amazon.de: hide PAGE_IDLE_FLAG from users]
Link: https://lkml.kernel.org/r/20210813081238.34705-1-sj38.park@gmail.com
Link: https://lkml.kernel.org/r/20210716081449.22187-5-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Even somehow the initial monitoring target regions are well constructed to
fulfill the assumption (pages in same region have similar access
frequencies), the data access pattern can be dynamically changed. This
will result in low monitoring quality. To keep the assumption as much as
possible, DAMON adaptively merges and splits each region based on their
access frequency.
For each ``aggregation interval``, it compares the access frequencies of
adjacent regions and merges those if the frequency difference is small.
Then, after it reports and clears the aggregated access frequency of each
region, it splits each region into two or three regions if the total
number of regions will not exceed the user-specified maximum number of
regions after the split.
In this way, DAMON provides its best-effort quality and minimal overhead
while keeping the upper-bound overhead that users set.
Link: https://lkml.kernel.org/r/20210716081449.22187-4-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To avoid the unbounded increase of the overhead, DAMON groups adjacent
pages that are assumed to have the same access frequencies into a
region. As long as the assumption (pages in a region have the same
access frequencies) is kept, only one page in the region is required to
be checked. Thus, for each ``sampling interval``,
1. the 'prepare_access_checks' primitive picks one page in each region,
2. waits for one ``sampling interval``,
3. checks whether the page is accessed meanwhile, and
4. increases the access count of the region if so.
Therefore, the monitoring overhead is controllable by adjusting the
number of regions. DAMON allows both the underlying primitives and user
callbacks to adjust regions for the trade-off. In other words, this
commit makes DAMON to use not only time-based sampling but also
space-based sampling.
This scheme, however, cannot preserve the quality of the output if the
assumption is not guaranteed. Next commit will address this problem.
Link: https://lkml.kernel.org/r/20210716081449.22187-3-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Introduce Data Access MONitor (DAMON)", v34.
Introduction
============
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON called 'region based sampling' and 'adaptive
regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this
patchset for the detail) make it
- accurate (The monitored information is useful for DRAM level memory
management. It might not appropriate for Cache-level accuracy,
though.),
- light-weight (The monitoring overhead is low enough to be applied
online while making no impact on the performance of the target
workloads.), and
- scalable (the upper-bound of the instrumentation overhead is
controllable regardless of the size of target workloads.).
Using this framework, therefore, several memory management mechanisms such
as reclamation and THP can be optimized to aware real data access
patterns. Experimental access pattern aware memory management
optimization works that incurring high instrumentation overhead will be
able to have another try.
Though DAMON is for kernel subsystems, it can be easily exposed to the
user space by writing a DAMON-wrapper kernel subsystem. Then, user space
users who have some special workloads will be able to write personalized
tools or applications for deeper understanding and specialized
optimizations of their systems.
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
[1] https://github.com/amazonlinux/linux/tree/amazon-5.4.y/master/mm/damon
[2] https://github.com/amazonlinux/linux/tree/amazon-5.10.y/master/mm/damon
The userspace tool[1] is available, released under GPLv2, and actively
being maintained. I am also planning to implement another basic user
interface in perf[2]. Also, the basic test suite for DAMON is available
under GPLv2[3].
[1] https://github.com/awslabs/damo
[2] https://lore.kernel.org/linux-mm/20210107120729.22328-1-sjpark@amazon.com/
[3] https://github.com/awslabs/damon-tests
Long-term Plan
--------------
DAMON is a part of a project called Data Access-aware Operating System
(DAOS). As the name implies, I want to improve the performance and
efficiency of systems using fine-grained data access patterns. The
optimizations are for both kernel and user spaces. I will therefore
modify or create kernel subsystems, export some of those to user space and
implement user space library / tools. Below shows the layers and
components for the project.
---------------------------------------------------------------------------
Primitives: PTE Accessed bit, PG_idle, rmap, (Intel CMT), ...
Framework: DAMON
Features: DAMOS, virtual addr, physical addr, ...
Applications: DAMON-debugfs, (DARC), ...
^^^^^^^^^^^^^^^^^^^^^^^ KERNEL SPACE ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Raw Interface: debugfs, (sysfs), (damonfs), tracepoints, (sys_damon), ...
vvvvvvvvvvvvvvvvvvvvvvv USER SPACE vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Library: (libdamon), ...
Tools: DAMO, (perf), ...
---------------------------------------------------------------------------
The components in parentheses or marked as '...' are not implemented yet
but in the future plan. IOW, those are the TODO tasks of DAOS project.
For more detail, please refer to the plans:
https://lore.kernel.org/linux-mm/20201202082731.24828-1-sjpark@amazon.com/
Evaluations
===========
We evaluated DAMON's overhead, monitoring quality and usefulness using 24
realistic workloads on my QEMU/KVM based virtual machine running a kernel
that v24 DAMON patchset is applied.
DAMON is lightweight. It increases system memory usage by 0.39% and slows
target workloads down by 1.16%.
DAMON is accurate and useful for memory management optimizations. An
experimental DAMON-based operation scheme for THP, namely 'ethp', removes
76.15% of THP memory overheads while preserving 51.25% of THP speedup.
Another experimental DAMON-based 'proactive reclamation' implementation,
'prcl', reduces 93.38% of residential sets and 23.63% of system memory
footprint while incurring only 1.22% runtime overhead in the best case
(parsec3/freqmine).
NOTE that the experimental THP optimization and proactive reclamation are
not for production but only for proof of concepts.
Please refer to the official document[1] or "Documentation/admin-guide/mm:
Add a document for DAMON" patch in this patchset for detailed evaluation
setup and results.
[1] https://damonitor.github.io/doc/html/latest-damon/admin-guide/mm/damon/eval.html
Real-world User Story
=====================
In summary, DAMON has used on production systems and proved its usefulness.
DAMON as a profiler
-------------------
We analyzed characteristics of a large scale production systems of our
customers using DAMON. The systems utilize 70GB DRAM and 36 CPUs. From
this, we were able to find interesting things below.
There were obviously different access pattern under idle workload and
active workload. Under the idle workload, it accessed large memory
regions with low frequency, while the active workload accessed small
memory regions with high freuqnecy.
DAMON found a 7GB memory region that showing obviously high access
frequency under the active workload. We believe this is the
performance-effective working set and need to be protected.
There was a 4KB memory region that showing highest access frequency under
not only active but also idle workloads. We think this must be a hottest
code section like thing that should never be paged out.
For this analysis, DAMON used only 0.3-1% of single CPU time. Because we
used recording-based analysis, it consumed about 3-12 MB of disk space per
20 minutes. This is only small amount of disk space, but we can further
reduce the disk usage by using non-recording-based DAMON features. I'd
like to argue that only DAMON can do such detailed analysis (finding 4KB
highest region in 70GB memory) with the light overhead.
DAMON as a system optimization tool
-----------------------------------
We also found below potential performance problems on the systems and made
DAMON-based solutions.
The system doesn't want to make the workload suffer from the page
reclamation and thus it utilizes enough DRAM but no swap device. However,
we found the system is actively reclaiming file-backed pages, because the
system has intensive file IO. The file IO turned out to be not
performance critical for the workload, but the customer wanted to ensure
performance critical file-backed pages like code section to not mistakenly
be evicted.
Using direct IO should or `mlock()` would be a straightforward solution,
but modifying the user space code is not easy for the customer.
Alternatively, we could use DAMON-based operation scheme[1]. By using it,
we can ask DAMON to track access frequency of each region and make
'process_madvise(MADV_WILLNEED)[2]' call for regions having specific size
and access frequency for a time interval.
We also found the system is having high number of TLB misses. We tried
'always' THP enabled policy and it greatly reduced TLB misses, but the
page reclamation also been more frequent due to the THP internal
fragmentation caused memory bloat. We could try another DAMON-based
operation scheme that applies 'MADV_HUGEPAGE' to memory regions having
>=2MB size and high access frequency, while applying 'MADV_NOHUGEPAGE' to
regions having <2MB size and low access frequency.
We do not own the systems so we only reported the analysis results and
possible optimization solutions to the customers. The customers satisfied
about the analysis results and promised to try the optimization guides.
[1] https://lore.kernel.org/linux-mm/20201006123931.5847-1-sjpark@amazon.com/
[2] https://lore.kernel.org/linux-api/20200622192900.22757-4-minchan@kernel.org/
Comparison with Idle Page Tracking
==================================
Idle Page Tracking allows users to set and read idleness of pages using a
bitmap file which represents each page with each bit of the file. One
recommended usage of it is working set size detection. Users can do that
by
1. find PFN of each page for workloads in interest,
2. set all the pages as idle by doing writes to the bitmap file,
3. wait until the workload accesses its working set, and
4. read the idleness of the pages again and count pages became not idle.
NOTE: While Idle Page Tracking is for user space users, DAMON is primarily
designed for kernel subsystems though it can easily exposed to the user
space. Hence, this section only assumes such user space use of DAMON.
For what use cases Idle Page Tracking would be better?
------------------------------------------------------
1. Flexible usecases other than hotness monitoring.
Because Idle Page Tracking allows users to control the primitive (Page
idleness) by themselves, Idle Page Tracking users can do anything they
want. Meanwhile, DAMON is primarily designed to monitor the hotness of
each memory region. For this, DAMON asks users to provide sampling
interval and aggregation interval. For the reason, there could be some
use case that using Idle Page Tracking is simpler.
2. Physical memory monitoring.
Idle Page Tracking receives PFN range as input, so natively supports
physical memory monitoring.
DAMON is designed to be extensible for multiple address spaces and use
cases by implementing and using primitives for the given use case.
Therefore, by theory, DAMON has no limitation in the type of target
address space as long as primitives for the given address space exists.
However, the default primitives introduced by this patchset supports only
virtual address spaces.
Therefore, for physical memory monitoring, you should implement your own
primitives and use it, or simply use Idle Page Tracking.
Nonetheless, RFC patchsets[1] for the physical memory address space
primitives is already available. It also supports user memory same to
Idle Page Tracking.
[1] https://lore.kernel.org/linux-mm/20200831104730.28970-1-sjpark@amazon.com/
For what use cases DAMON is better?
-----------------------------------
1. Hotness Monitoring.
Idle Page Tracking let users know only if a page frame is accessed or not.
For hotness check, the user should write more code and use more memory.
DAMON do that by itself.
2. Low Monitoring Overhead
DAMON receives user's monitoring request with one step and then provide
the results. So, roughly speaking, DAMON require only O(1) user/kernel
context switches.
In case of Idle Page Tracking, however, because the interface receives
contiguous page frames, the number of user/kernel context switches
increases as the monitoring target becomes complex and huge. As a result,
the context switch overhead could be not negligible.
Moreover, DAMON is born to handle with the monitoring overhead. Because
the core mechanism is pure logical, Idle Page Tracking users might be able
to implement the mechanism on their own, but it would be time consuming
and the user/kernel context switching will still more frequent than that
of DAMON. Also, the kernel subsystems cannot use the logic in this case.
3. Page granularity working set size detection.
Until v22 of this patchset, this was categorized as the thing Idle Page
Tracking could do better, because DAMON basically maintains additional
metadata for each of the monitoring target regions. So, in the page
granularity working set size detection use case, DAMON would incur (number
of monitoring target pages * size of metadata) memory overhead. Size of
the single metadata item is about 54 bytes, so assuming 4KB pages, about
1.3% of monitoring target pages will be additionally used.
All essential metadata for Idle Page Tracking are embedded in 'struct
page' and page table entries. Therefore, in this use case, only one
counter variable for working set size accounting is required if Idle Page
Tracking is used.
There are more details to consider, but roughly speaking, this is true in
most cases.
However, the situation changed from v23. Now DAMON supports arbitrary
types of monitoring targets, which don't use the metadata. Using that,
DAMON can do the working set size detection with no additional space
overhead but less user-kernel context switch. A first draft for the
implementation of monitoring primitives for this usage is available in a
DAMON development tree[1]. An RFC patchset for it based on this patchset
will also be available soon.
Since v24, the arbitrary type support is dropped from this patchset
because this patchset doesn't introduce real use of the type. You can
still get it from the DAMON development tree[2], though.
[1] https://github.com/sjp38/linux/tree/damon/pgidle_hack
[2] https://github.com/sjp38/linux/tree/damon/master
4. More future usecases
While Idle Page Tracking has tight coupling with base primitives (PG_Idle
and page table Accessed bits), DAMON is designed to be extensible for many
use cases and address spaces. If you need some special address type or
want to use special h/w access check primitives, you can write your own
primitives for that and configure DAMON to use those. Therefore, if your
use case could be changed a lot in future, using DAMON could be better.
Can I use both Idle Page Tracking and DAMON?
--------------------------------------------
Yes, though using them concurrently for overlapping memory regions could
result in interference to each other. Nevertheless, such use case would
be rare or makes no sense at all. Even in the case, the noise would bot
be really significant. So, you can choose whatever you want depending on
the characteristics of your use cases.
More Information
================
We prepared a showcase web site[1] that you can get more information.
There are
- the official documentations[2],
- the heatmap format dynamic access pattern of various realistic workloads for
heap area[3], mmap()-ed area[4], and stack[5] area,
- the dynamic working set size distribution[6] and chronological working set
size changes[7], and
- the latest performance test results[8].
[1] https://damonitor.github.io/_index
[2] https://damonitor.github.io/doc/html/latest-damon
[3] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.0.png.html
[4] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
[5] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.2.png.html
[6] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
[7] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html
[8] https://damonitor.github.io/test/result/perf/latest/html/index.html
Baseline and Complete Git Trees
===============================
The patches are based on the latest -mm tree, specifically
v5.14-rc1-mmots-2021-07-15-18-47 of https://github.com/hnaz/linux-mm. You can
also clone the complete git tree:
$ git clone git://github.com/sjp38/linux -b damon/patches/v34
The web is also available:
https://github.com/sjp38/linux/releases/tag/damon/patches/v34
Development Trees
-----------------
There are a couple of trees for entire DAMON patchset series and features
for future release.
- For latest release: https://github.com/sjp38/linux/tree/damon/master
- For next release: https://github.com/sjp38/linux/tree/damon/next
Long-term Support Trees
-----------------------
For people who want to test DAMON but using LTS kernels, there are another
couple of trees based on two latest LTS kernels respectively and
containing the 'damon/master' backports.
- For v5.4.y: https://github.com/sjp38/linux/tree/damon/for-v5.4.y
- For v5.10.y: https://github.com/sjp38/linux/tree/damon/for-v5.10.y
Amazon Linux Kernel Trees
-------------------------
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
[1] https://github.com/amazonlinux/linux/tree/amazon-5.4.y/master/mm/damon
[2] https://github.com/amazonlinux/linux/tree/amazon-5.10.y/master/mm/damon
Git Tree for Diff of Patches
============================
For easy review of diff between different versions of each patch, I
prepared a git tree containing all versions of the DAMON patchset series:
https://github.com/sjp38/damon-patches
You can clone it and use 'diff' for easy review of changes between
different versions of the patchset. For example:
$ git clone https://github.com/sjp38/damon-patches && cd damon-patches
$ diff -u damon/v33 damon/v34
Sequence Of Patches
===================
First three patches implement the core logics of DAMON. The 1st patch
introduces basic sampling based hotness monitoring for arbitrary types of
targets. Following two patches implement the core mechanisms for control
of overhead and accuracy, namely regions based sampling (patch 2) and
adaptive regions adjustment (patch 3).
Now the essential parts of DAMON is complete, but it cannot work unless
someone provides monitoring primitives for a specific use case. The
following two patches make it just work for virtual address spaces
monitoring. The 4th patch makes 'PG_idle' can be used by DAMON and the
5th patch implements the virtual memory address space specific monitoring
primitives using page table Accessed bits and the 'PG_idle' page flag.
Now DAMON just works for virtual address space monitoring via the kernel
space api. To let the user space users can use DAMON, following four
patches add interfaces for them. The 6th patch adds a tracepoint for
monitoring results. The 7th patch implements a DAMON application kernel
module, namely damon-dbgfs, that simply wraps DAMON and exposes DAMON
interface to the user space via the debugfs interface. The 8th patch
further exports pid of monitoring thread (kdamond) to user space for
easier cpu usage accounting, and the 9th patch makes the debugfs interface
to support multiple contexts.
Three patches for maintainability follows. The 10th patch adds
documentations for both the user space and the kernel space. The 11th
patch provides unit tests (based on the kunit) while the 12th patch adds
user space tests (based on the kselftest).
Finally, the last patch (13th) updates the MAINTAINERS file.
This patch (of 13):
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON make it
- accurate (the monitoring output is useful enough for DRAM level
performance-centric memory management; It might be inappropriate for
CPU cache levels, though),
- light-weight (the monitoring overhead is normally low enough to be
applied online), and
- scalable (the upper-bound of the overhead is in constant range
regardless of the size of target workloads).
Using this framework, hence, we can easily write efficient kernel space
data access monitoring applications. For example, the kernel's memory
management mechanisms can make advanced decisions using this.
Experimental data access aware optimization works that incurring high
access monitoring overhead could again be implemented on top of this.
Due to its simple and flexible interface, providing user space interface
would be also easy. Then, user space users who have some special
workloads can write personalized applications for better understanding and
optimizations of their workloads and systems.
===
Nevertheless, this commit is defining and implementing only basic access
check part without the overhead-accuracy handling core logic. The basic
access check is as below.
The output of DAMON says what memory regions are how frequently accessed
for a given duration. The resolution of the access frequency is
controlled by setting ``sampling interval`` and ``aggregation interval``.
In detail, DAMON checks access to each page per ``sampling interval`` and
aggregates the results. In other words, counts the number of the accesses
to each region. After each ``aggregation interval`` passes, DAMON calls
callback functions that previously registered by users so that users can
read the aggregated results and then clears the results. This can be
described in below simple pseudo-code::
init()
while monitoring_on:
for page in monitoring_target:
if accessed(page):
nr_accesses[page] += 1
if time() % aggregation_interval == 0:
for callback in user_registered_callbacks:
callback(monitoring_target, nr_accesses)
for page in monitoring_target:
nr_accesses[page] = 0
if time() % update_interval == 0:
update()
sleep(sampling interval)
The target regions constructed at the beginning of the monitoring and
updated after each ``regions_update_interval``, because the target regions
could be dynamically changed (e.g., mmap() or memory hotplug). The
monitoring overhead of this mechanism will arbitrarily increase as the
size of the target workload grows.
The basic monitoring primitives for actual access check and dynamic target
regions construction aren't in the core part of DAMON. Instead, it allows
users to implement their own primitives that are optimized for their use
case and configure DAMON to use those. In other words, users cannot use
current version of DAMON without some additional works.
Following commits will implement the core mechanisms for the
overhead-accuracy control and default primitives implementations.
Link: https://lkml.kernel.org/r/20210716081449.22187-1-sj38.park@gmail.com
Link: https://lkml.kernel.org/r/20210716081449.22187-2-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Marco Elver <elver@google.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fail kfence_test fast if KFENCE was disabled at boot, instead of each test
case trying several seconds to allocate from KFENCE and failing. KUnit
will fail all test cases if kunit_suite::init returns an error.
Even if KFENCE was disabled, we still want the test to fail, so that CI
systems that parse KUnit output will alert on KFENCE being disabled
(accidentally or otherwise).
Link: https://lkml.kernel.org/r/20210825105533.1247922-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Record cpu and timestamp on allocations and frees, and show them in
reports. Upon an error, this can help correlate earlier messages in the
kernel log via allocation and free timestamps.
Link: https://lkml.kernel.org/r/20210714175312.2947941-1-elver@google.com
Suggested-by: Joern Engel <joern@purestorage.com>
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Acked-by: Joern Engel <joern@purestorage.com>
Cc: Yuanyuan Zhong <yzhong@purestorage.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a secret memory region is active, memfd_secret disables hibernation.
One of the goals is to keep the secret data from being written to
persistent-storage.
It accomplishes this by maintaining a reference count to
`secretmem_users`. Once this reference is held your system can not be
hibernated due to the check in `hibernation_available()`. However,
because `secretmem_users` is of type `atomic_t`, reference counter
overflows are possible.
As you can see there's an `atomic_inc` for each `memfd` that is opened in
the `memfd_secret` syscall. If a local attacker succeeds to open 2^32
memfd's, the counter will wrap around to 0. This implies that you may
hibernate again, even though there are still regions of this secret
memory, thereby bypassing the security check.
In an attempt to fix this I have used `refcount_t` instead of `atomic_t`
which prevents reference counter overflows.
Link: https://lkml.kernel.org/r/20210820043339.2151352-1-jordy@pwning.systems
Signed-off-by: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: Jordy Zomer <jordy@jordyzomer.github.io>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace the obsolete and ambiguos macro in_irq() with new macro
in_hardirq().
Link: https://lkml.kernel.org/r/20210813145245.86070-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com> [kmemleak]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
early_ioremap_reset() reserved a weak function so that architectures can
provide a specific cleanup. Now no architectures use it, remove this
redundant function.
Link: https://lkml.kernel.org/r/20210901082917.399953-1-o451686892@gmail.com
Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no need to execute from iomem (and most platforms it is
impossible anyway), so add the pgprot_nx() call similar to vmap.
Link: https://lkml.kernel.org/r/20210824091259.1324527-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "small ioremap cleanups".
The first patch moves a little code around the vmalloc/ioremap boundary
following a bigger move by Nick earlier. The second enforces
non-executable mapping on ioremap just like we do for vmap. No driver
currently uses executable mappings anyway, as they should.
This patch (of 2):
This keeps it together with the implementation, and to remove the
vmap_range wrapper.
Link: https://lkml.kernel.org/r/20210824091259.1324527-1-hch@lst.de
Link: https://lkml.kernel.org/r/20210824091259.1324527-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a READ_ONCE() in the macro of compound_head(), which will prevent
compiler from optimizing the code when there are more than once calling of
it in a function. Remove the redundant calling of compound_head() from
page_to_index() and page_add_file_rmap() for better code generation.
Link: https://lkml.kernel.org/r/20210811101431.83940-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Cleanup and fixups for memory hotplug".
This series contains cleanup to use helper function to simplify the code.
Also we fix some potential bugs. More details can be found in the
respective changelogs.
This patch (of 3):
Use helper zone_is_zone_device() to simplify the code and remove some
explicit CONFIG_ZONE_DEVICE codes.
Link: https://lkml.kernel.org/r/20210821094246.10149-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210821094246.10149-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the "auto-movable" online policy does not allow for hotplugged
KERNEL (ZONE_NORMAL) memory to increase the amount of MOVABLE memory we
can have, primarily, because there is no coordiantion across memory
devices and we don't want to create zone-imbalances accidentially when
unplugging memory.
However, within a single memory device it's different. Let's allow for
KERNEL memory within a dynamic memory group to allow for more MOVABLE
within the same memory group. The only thing we have to take care of is
that the managing driver avoids zone imbalances by unplugging MOVABLE
memory first, otherwise there can be corner cases where unplug of memory
could result in (accidential) zone imbalances.
virtio-mem is the only user of dynamic memory groups and recently added
support for prioritizing unplug of ZONE_MOVABLE over ZONE_NORMAL, so we
don't need a new toggle to enable it for dynamic memory groups.
We limit this handling to dynamic memory groups, because:
* We want to keep the runtime overhead for collecting stats when
onlining a single memory block small. We tend to have only a handful of
dynamic memory groups, but we can have quite some static memory groups
(e.g., 256 DIMMs).
* It doesn't make too much sense for static memory groups, as we try
onlining all applicable memory blocks either completely to ZONE_MOVABLE
or not. In ordinary operation, we won't have a mixture of zones within
a static memory group.
When adding memory to a dynamic memory group, we'll first online memory to
ZONE_MOVABLE as long as early KERNEL memory allows for it. Then, we'll
online the next unit(s) to ZONE_NORMAL, until we can online the next
unit(s) to ZONE_MOVABLE.
For a simple virtio-mem device with a MOVABLE:KERNEL ratio of 3:1, it will
result in a layout like:
[M][M][M][M][M][M][M][M][N][M][M][M][N][M][M][M]...
^ movable memory due to early kernel memory
^ allows for more movable memory ...
^-----^ ... here
^ allows for more movable memory ...
^-----^ ... here
While the created layout is sub-optimal when it comes to contiguous zones,
it gives us the maximum flexibility when dynamically growing/shrinking a
device; we can grow small VMs really big in small steps, and still shrink
reliably to e.g., 1/4 of the maximum VM size in this example, removing
full memory blocks along with meta data more reliably.
Mark dynamic memory groups in the xarray such that we can efficiently
iterate over them when collecting stats. In usual setups, we have one
virtio-mem device per NUMA node, and usually only a small number of NUMA
nodes.
Note: for now, there seems to be no compelling reason to make this
behavior configurable.
Link: https://lkml.kernel.org/r/20210806124715.17090-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use memory groups to improve our "auto-movable" onlining policy:
1. For static memory groups (e.g., a DIMM), online a memory block MOVABLE
only if all other memory blocks in the group are either MOVABLE or could
be onlined MOVABLE. A DIMM will either be MOVABLE or not, not a mixture.
2. For dynamic memory groups (e.g., a virtio-mem device), online a
memory block MOVABLE only if all other memory blocks inside the
current unit are either MOVABLE or could be onlined MOVABLE. For a
virtio-mem device with a device block size with 512 MiB, all 128 MiB
memory blocks wihin a 512 MiB unit will either be MOVABLE or not, not
a mixture.
We have to pass the memory group to zone_for_pfn_range() to take the
memory group into account.
Note: for now, there seems to be no compelling reason to make this
behavior configurable.
Link: https://lkml.kernel.org/r/20210806124715.17090-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Let's track all present pages in each memory group. Especially, track
memory present in ZONE_MOVABLE and memory present in one of the kernel
zones (which really only is ZONE_NORMAL right now as memory groups only
apply to hotplugged memory) separately within a memory group, to prepare
for making smart auto-online decision for individual memory blocks within
a memory group based on group statistics.
Link: https://lkml.kernel.org/r/20210806124715.17090-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In our "auto-movable" memory onlining policy, we want to make decisions
across memory blocks of a single memory device. Examples of memory
devices include ACPI memory devices (in the simplest case a single DIMM)
and virtio-mem. For now, we don't have a connection between a single
memory block device and the real memory device. Each memory device
consists of 1..X memory block devices.
Let's logically group memory blocks belonging to the same memory device in
"memory groups". Memory groups can span multiple physical ranges and a
memory group itself does not contain any information regarding physical
ranges, only properties (e.g., "max_pages") necessary for improved memory
onlining.
Introduce two memory group types:
1) Static memory group: E.g., a single ACPI memory device, consisting
of 1..X memory resources. A memory group consists of 1..Y memory
blocks. The whole group is added/removed in one go. If any part
cannot get offlined, the whole group cannot be removed.
2) Dynamic memory group: E.g., a single virtio-mem device. Memory is
dynamically added/removed in a fixed granularity, called a "unit",
consisting of 1..X memory blocks. A unit is added/removed in one go.
If any part of a unit cannot get offlined, the whole unit cannot be
removed.
In case of 1) we usually want either all memory managed by ZONE_MOVABLE or
none. In case of 2) we usually want to have as many units as possible
managed by ZONE_MOVABLE. We want a single unit to be of the same type.
For now, memory groups are an internal concept that is not exposed to user
space; we might want to change that in the future, though.
add_memory() users can specify a mgid instead of a nid when passing the
MHP_NID_IS_MGID flag.
Link: https://lkml.kernel.org/r/20210806124715.17090-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When onlining without specifying a zone (using "online" instead of
"online_kernel" or "online_movable"), we currently select a zone such that
existing zones are kept contiguous. This online policy made sense in the
past, where contiguous zones where required.
We'd like to implement smarter policies, however:
* User space has little insight. As one example, it has no idea which
memory blocks logically belong together (e.g., to a DIMM or to a
virtio-mem device).
* Drivers that add memory in separate memory blocks, especially
virtio-mem, want memory to get onlined right from the kernel when
adding.
So we really want to have onlining to differing zones managed in the
kernel, configured by user space.
We see more and more cases where we might eventually hotplug a lot of
memory in the future (e.g., eventually grow a 2 GiB VM to 64 GiB),
however:
* Resizing happens dynamically, in smaller steps in both directions
(e.g., 2 GiB -> 8 GiB -> 4 GiB -> 16 GiB ...)
* We still want as much flexibility as possible, especially,
hotunplugging as much memory as possible later.
We can really only use "online_movable" if we know that the amount of
memory we are going to hotplug upfront, and we know that it won't result
in a zone imbalance. So in our example, a 2 GiB VM that could grow to 64
GiB could currently not use "online_movable", and instead, "online_kernel"
would have to be used, resulting in worse (no) memory hotunplug
reliability.
Let's add a new "auto-movable" online policy that considers the current
zone ratios (global, per-node) to determine, whether we a memory block can
be onlined to ZONE_MOVABLE:
MOVABLE : KERNEL
However, internally we'll only consider the following ratio for now:
MOVABLE : KERNEL_EARLY
For now, we don't allow for hotplugged KERNEL memory to allow for more
MOVABLE memory, because there is no coordination across memory devices.
In follow-up patches, we will allow for more KERNEL memory within a memory
device to allow for more MOVABLE memory within the same memory device --
which only makes sense for special memory device types.
We base our calculation on "present pages", see the code comments for
details. Hotplugged memory will get online to ZONE_MOVABLE if the
configured ratio allows for it. Depending on the setup, this can result
in fragmented zones, which can make compaction slower and dynamic
allocation of gigantic pages when not using CMA less reliable (... which
is already pretty unreliable).
The old policy will be the default and called "contig-zones". In
follow-up patches, our new policy will use additional information, such as
memory groups, to make even smarter decisions across memory blocks.
Configuration:
* memory_hotplug.online_policy is used to switch between both polices
and defaults to "contig-zones".
* memory_hotplug.auto_movable_ratio defines the maximum ratio is in
percent and defaults to "301" -- allowing e.g., most 8 GiB machines to
grow to 32 GiB and have all hotplugged memory in ZONE_MOVABLE. The
additional percent accounts for a handful of lost present pages (e.g.,
firmware allocations). User space is expected to adjust this ratio when
enabling the new "auto-movable" policy, though.
* memory_hotplug.auto_movable_numa_aware considers numa node stats in
addition to global stats, and defaults to "true".
Note: just like the old policy, the new policy won't take things like
unmovable huge pages or memory ballooning that doesn't support balloon
compaction into account. User space has to configure onlining
accordingly.
Link: https://lkml.kernel.org/r/20210806124715.17090-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/memory_hotplug: "auto-movable" online policy and memory groups", v3.
I. Goal
The goal of this series is improving in-kernel auto-online support. It
tackles the fundamental problems that:
1) We can create zone imbalances when onlining all memory blindly to
ZONE_MOVABLE, in the worst case crashing the system. We have to know
upfront how much memory we are going to hotplug such that we can
safely enable auto-onlining of all hotplugged memory to ZONE_MOVABLE
via "online_movable". This is far from practical and only applicable in
limited setups -- like inside VMs under the RHV/oVirt hypervisor which
will never hotplug more than 3 times the boot memory (and the
limitation is only in place due to the Linux limitation).
2) We see more setups that implement dynamic VM resizing, hot(un)plugging
memory to resize VM memory. In these setups, we might hotplug a lot of
memory, but it might happen in various small steps in both directions
(e.g., 2 GiB -> 8 GiB -> 4 GiB -> 16 GiB ...). virtio-mem is the
primary driver of this upstream right now, performing such dynamic
resizing NUMA-aware via multiple virtio-mem devices.
Onlining all hotplugged memory to ZONE_NORMAL means we basically have
no hotunplug guarantees. Onlining all to ZONE_MOVABLE means we can
easily run into zone imbalances when growing a VM. We want a mixture,
and we want as much memory as reasonable/configured in ZONE_MOVABLE.
Details regarding zone imbalances can be found at [1].
3) Memory devices consist of 1..X memory block devices, however, the
kernel doesn't really track the relationship. Consequently, also user
space has no idea. We want to make per-device decisions.
As one example, for memory hotunplug it doesn't make sense to use a
mixture of zones within a single DIMM: we want all MOVABLE if
possible, otherwise all !MOVABLE, because any !MOVABLE part will easily
block the whole DIMM from getting hotunplugged.
As another example, virtio-mem operates on individual units that span
1..X memory blocks. Similar to a DIMM, we want a unit to either be all
MOVABLE or !MOVABLE. A "unit" can be thought of like a DIMM, however,
all units of a virtio-mem device logically belong together and are
managed (added/removed) by a single driver. We want as much memory of
a virtio-mem device to be MOVABLE as possible.
4) We want memory onlining to be done right from the kernel while adding
memory, not triggered by user space via udev rules; for example, this
is reqired for fast memory hotplug for drivers that add individual
memory blocks, like virito-mem. We want a way to configure a policy in
the kernel and avoid implementing advanced policies in user space.
The auto-onlining support we have in the kernel is not sufficient. All we
have is a) online everything MOVABLE (online_movable) b) online everything
!MOVABLE (online_kernel) c) keep zones contiguous (online). This series
allows configuring c) to mean instead "online movable if possible
according to the coniguration, driven by a maximum MOVABLE:KERNEL ratio"
-- a new onlining policy.
II. Approach
This series does 3 things:
1) Introduces the "auto-movable" online policy that initially operates on
individual memory blocks only. It uses a maximum MOVABLE:KERNEL ratio
to make a decision whether a memory block will be onlined to
ZONE_MOVABLE or not. However, in the basic form, hotplugged KERNEL
memory does not allow for more MOVABLE memory (details in the
patches). CMA memory is treated like MOVABLE memory.
2) Introduces static (e.g., DIMM) and dynamic (e.g., virtio-mem) memory
groups and uses group information to make decisions in the
"auto-movable" online policy across memory blocks of a single memory
device (modeled as memory group). More details can be found in patch
#3 or in the DIMM example below.
3) Maximizes ZONE_MOVABLE memory within dynamic memory groups, by
allowing ZONE_NORMAL memory within a dynamic memory group to allow for
more ZONE_MOVABLE memory within the same memory group. The target use
case is dynamic VM resizing using virtio-mem. See the virtio-mem
example below.
I remember that the basic idea of using a ratio to implement a policy in
the kernel was once mentioned by Vitaly Kuznetsov, but I might be wrong (I
lost the pointer to that discussion).
For me, the main use case is using it along with virtio-mem (and DIMMs /
ppc64 dlpar where necessary) for dynamic resizing of VMs, increasing the
amount of memory we can hotunplug reliably again if we might eventually
hotplug a lot of memory to a VM.
III. Target Usage
The target usage will be:
1) Linux boots with "mhp_default_online_type=offline"
2) User space (e.g., systemd unit) configures memory onlining (according
to a config file and system properties), for example:
* Setting memory_hotplug.online_policy=auto-movable
* Setting memory_hotplug.auto_movable_ratio=301
* Setting memory_hotplug.auto_movable_numa_aware=true
3) User space enabled auto onlining via "echo online >
/sys/devices/system/memory/auto_online_blocks"
4) User space triggers manual onlining of all already-offline memory
blocks (go over offline memory blocks and set them to "online")
IV. Example
For DIMMs, hotplugging 4 GiB DIMMs to a 4 GiB VM with a configured ratio of
301% results in the following layout:
Memory block 0-15: DMA32 (early)
Memory block 32-47: Normal (early)
Memory block 48-79: Movable (DIMM 0)
Memory block 80-111: Movable (DIMM 1)
Memory block 112-143: Movable (DIMM 2)
Memory block 144-275: Normal (DIMM 3)
Memory block 176-207: Normal (DIMM 4)
... all Normal
(-> hotplugged Normal memory does not allow for more Movable memory)
For virtio-mem, using a simple, single virtio-mem device with a 4 GiB VM
will result in the following layout:
Memory block 0-15: DMA32 (early)
Memory block 32-47: Normal (early)
Memory block 48-143: Movable (virtio-mem, first 12 GiB)
Memory block 144: Normal (virtio-mem, next 128 MiB)
Memory block 145-147: Movable (virtio-mem, next 384 MiB)
Memory block 148: Normal (virtio-mem, next 128 MiB)
Memory block 149-151: Movable (virtio-mem, next 384 MiB)
... Normal/Movable mixture as above
(-> hotplugged Normal memory allows for more Movable memory within
the same device)
Which gives us maximum flexibility when dynamically growing/shrinking a
VM in smaller steps.
V. Doc Update
I'll update the memory-hotplug.rst documentation, once the overhaul [1] is
usptream. Until then, details can be found in patch #2.
VI. Future Work
1) Use memory groups for ppc64 dlpar
2) Being able to specify a portion of (early) kernel memory that will be
excluded from the ratio. Like "128 MiB globally/per node" are excluded.
This might be helpful when starting VMs with extremely small memory
footprint (e.g., 128 MiB) and hotplugging memory later -- not wanting
the first hotplugged units getting onlined to ZONE_MOVABLE. One
alternative would be a trigger to not consider ZONE_DMA memory
in the ratio. We'll have to see if this is really rrequired.
3) Indicate to user space that MOVABLE might be a bad idea -- especially
relevant when memory ballooning without support for balloon compaction
is active.
This patch (of 9):
For implementing a new memory onlining policy, which determines when to
online memory blocks to ZONE_MOVABLE semi-automatically, we need the
number of present early (boot) pages -- present pages excluding hotplugged
pages. Let's track these pages per zone.
Pass a page instead of the zone to adjust_present_page_count(), similar as
adjust_managed_page_count() and derive the zone from the page.
It's worth noting that a memory block to be offlined/onlined is either
completely "early" or "not early". add_memory() and friends can only add
complete memory blocks and we only online/offline complete (individual)
memory blocks.
Link: https://lkml.kernel.org/r/20210806124715.17090-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210806124715.17090-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is only a single user remaining. We can simply lookup the nid only
used for node offlining purposes when walking our memory blocks. We don't
expect to remove multi-nid ranges; and if we'd ever do, we most probably
don't care about removing multi-nid ranges that actually result in empty
nodes.
If ever required, we can detect the "multi-nid" scenario and simply try
offlining all online nodes.
Link: https://lkml.kernel.org/r/20210712124052.26491-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jia He <justin.he@arm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pankaj.gupta@ionos.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Sergei Trofimovich <slyfox@gentoo.org>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/memory_hotplug: preparatory patches for new online policy and memory"
These are all cleanups and one fix previously sent as part of [1]:
[PATCH v1 00/12] mm/memory_hotplug: "auto-movable" online policy and memory
groups.
These patches make sense even without the other series, therefore I pulled
them out to make the other series easier to digest.
[1] https://lkml.kernel.org/r/20210607195430.48228-1-david@redhat.com
This patch (of 4):
Checkpatch complained on a follow-up patch that we are using "unsigned"
here, which defaults to "unsigned int" and checkpatch is correct.
As we will search for a fitting zone using the wrong pfn, we might end
up onlining memory to one of the special kernel zones, such as ZONE_DMA,
which can end badly as the onlined memory does not satisfy properties of
these zones.
Use "unsigned long" instead, just as we do in other places when handling
PFNs. This can bite us once we have physical addresses in the range of
multiple TB.
Link: https://lkml.kernel.org/r/20210712124052.26491-2-david@redhat.com
Fixes: e5e6893026 ("mm, memory_hotplug: display allowed zones in the preferred ordering")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: virtualization@lists.linux-foundation.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jia He <justin.he@arm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Sergei Trofimovich <slyfox@gentoo.org>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When test_pages_in_a_zone() used pfn_valid_within() is has some logic
surrounding pfn_valid_within() checks.
Since pfn_valid_within() is gone, this logic can be removed.
Link: https://lkml.kernel.org/r/20210713080035.7464-3-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE".
After recent updates to freeing unused parts of the memory map, no
architecture can have holes in the memory map within a pageblock. This
makes pfn_valid_within() check and CONFIG_HOLES_IN_ZONE configuration
option redundant.
The first patch removes them both in a mechanical way and the second patch
simplifies memory_hotplug::test_pages_in_a_zone() that had
pfn_valid_within() surrounded by more logic than simple if.
This patch (of 2):
After recent changes in freeing of the unused parts of the memory map and
rework of pfn_valid() in arm and arm64 there are no architectures that can
have holes in the memory map within a pageblock and so nothing can enable
CONFIG_HOLES_IN_ZONE which guards non trivial implementation of
pfn_valid_within().
With that, pfn_valid_within() is always hardwired to 1 and can be
completely removed.
Remove calls to pfn_valid_within() and CONFIG_HOLES_IN_ZONE.
Link: https://lkml.kernel.org/r/20210713080035.7464-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20210713080035.7464-2-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 9857a17f20.
That commit was completely broken, and I should have caught on to it
earlier. But happily, the kernel test robot noticed the breakage fairly
quickly.
The breakage is because "try_get_page()" is about avoiding the page
reference count overflow case, but is otherwise the exact same as a
plain "get_page()".
In contrast, "try_get_compound_head()" is an entirely different beast,
and uses __page_cache_add_speculative() because it's not just about the
page reference count, but also about possibly racing with the underlying
page going away.
So all the commentary about how
"try_get_page() has fallen a little behind in terms of maintenance,
try_get_compound_head() handles speculative page references more
thoroughly"
was just completely wrong: yes, try_get_compound_head() handles
speculative page references, but the point is that try_get_page() does
not, and must not.
So there's no lack of maintainance - there are fundamentally different
semantics.
A speculative page reference would be entirely wrong in "get_page()",
and it's entirely wrong in "try_get_page()". It's not about
speculation, it's purely about "uhhuh, you can't get this page because
you've tried to increment the reference count too much already".
The reason the kernel test robot noticed this bug was that it hit the
VM_BUG_ON() in __page_cache_add_speculative(), which is all about
verifying that the context of any speculative page access is correct.
But since that isn't what try_get_page() is all about, the VM_BUG_ON()
tests things that are not correct to test for try_get_page().
Reported-by: kernel test robot <oliver.sang@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull MAP_DENYWRITE removal from David Hildenbrand:
"Remove all in-tree usage of MAP_DENYWRITE from the kernel and remove
VM_DENYWRITE.
There are some (minor) user-visible changes:
- We no longer deny write access to shared libaries loaded via legacy
uselib(); this behavior matches modern user space e.g. dlopen().
- We no longer deny write access to the elf interpreter after exec
completed, treating it just like shared libraries (which it often
is).
- We always deny write access to the file linked via /proc/pid/exe:
sys_prctl(PR_SET_MM_MAP/EXE_FILE) will fail if write access to the
file cannot be denied, and write access to the file will remain
denied until the link is effectivel gone (exec, termination,
sys_prctl(PR_SET_MM_MAP/EXE_FILE)) -- just as if exec'ing the file.
Cross-compiled for a bunch of architectures (alpha, microblaze, i386,
s390x, ...) and verified via ltp that especially the relevant tests
(i.e., creat07 and execve04) continue working as expected"
* tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux:
fs: update documentation of get_write_access() and friends
mm: ignore MAP_DENYWRITE in ksys_mmap_pgoff()
mm: remove VM_DENYWRITE
binfmt: remove in-tree usage of MAP_DENYWRITE
kernel/fork: always deny write access to current MM exe_file
kernel/fork: factor out replacing the current MM exe_file
binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib()
Embed local_lock into struct kmem_cpu_slab and use the irq-safe versions of
local_lock instead of plain local_irq_save/restore. On !PREEMPT_RT that's
equivalent, with better lockdep visibility. On PREEMPT_RT that means better
preemption.
However, the cost on PREEMPT_RT is the loss of lockless fast paths which only
work with cpu freelist. Those are designed to detect and recover from being
preempted by other conflicting operations (both fast or slow path), but the
slow path operations assume they cannot be preempted by a fast path operation,
which is guaranteed naturally with disabled irqs. With local locks on
PREEMPT_RT, the fast paths now also need to take the local lock to avoid races.
In the allocation fastpath slab_alloc_node() we can just defer to the slowpath
__slab_alloc() which also works with cpu freelist, but under the local lock.
In the free fastpath do_slab_free() we have to add a new local lock protected
version of freeing to the cpu freelist, as the existing slowpath only works
with the page freelist.
Also update the comment about locking scheme in SLUB to reflect changes done
by this series.
[ Mike Galbraith <efault@gmx.de>: use local_lock() without irq in PREEMPT_RT
scope; debugging of RT crashes resulting in put_cpu_partial() locking changes ]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
We currently use preempt_disable() (directly or via get_cpu_ptr()) to stabilize
the pointer to kmem_cache_cpu. On PREEMPT_RT this would be incompatible with
the list_lock spinlock. We can use migrate_disable() instead, but that
increases overhead on !PREEMPT_RT as it's an unconditional function call.
In order to get the best available mechanism on both PREEMPT_RT and
!PREEMPT_RT, introduce private slub_get_cpu_ptr() and slub_put_cpu_ptr()
wrappers and use them.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Jann Horn reported [1] the following theoretically possible race:
task A: put_cpu_partial() calls preempt_disable()
task A: oldpage = this_cpu_read(s->cpu_slab->partial)
interrupt: kfree() reaches unfreeze_partials() and discards the page
task B (on another CPU): reallocates page as page cache
task A: reads page->pages and page->pobjects, which are actually
halves of the pointer page->lru.prev
task B (on another CPU): frees page
interrupt: allocates page as SLUB page and places it on the percpu partial list
task A: this_cpu_cmpxchg() succeeds
which would cause page->pages and page->pobjects to end up containing
halves of pointers that would then influence when put_cpu_partial()
happens and show up in root-only sysfs files. Maybe that's acceptable,
I don't know. But there should probably at least be a comment for now
to point out that we're reading union fields of a page that might be
in a completely different state.
Additionally, the this_cpu_cmpxchg() approach in put_cpu_partial() is only safe
against s->cpu_slab->partial manipulation in ___slab_alloc() if the latter
disables irqs, otherwise a __slab_free() in an irq handler could call
put_cpu_partial() in the middle of ___slab_alloc() manipulating ->partial
and corrupt it. This becomes an issue on RT after a local_lock is introduced
in later patch. The fix means taking the local_lock also in put_cpu_partial()
on RT.
After debugging this issue, Mike Galbraith suggested [2] that to avoid
different locking schemes on RT and !RT, we can just protect put_cpu_partial()
with disabled irqs (to be converted to local_lock_irqsave() later) everywhere.
This should be acceptable as it's not a fast path, and moving the actual
partial unfreezing outside of the irq disabled section makes it short, and with
the retry loop gone the code can be also simplified. In addition, the race
reported by Jann should no longer be possible.
[1] https://lore.kernel.org/lkml/CAG48ez1mvUuXwg0YPH5ANzhQLpbphqk-ZS+jbRz+H66fvm4FcA@mail.gmail.com/
[2] https://lore.kernel.org/linux-rt-users/e3470ab357b48bccfbd1f5133b982178a7d2befb.camel@gmx.de/
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
We need to disable irqs around slab_lock() (a bit spinlock) to make it
irq-safe. Most calls to slab_lock() are nested under spin_lock_irqsave() which
doesn't disable irqs on PREEMPT_RT, so add explicit disabling with PREEMPT_RT.
The exception is cmpxchg_double_slab() which already disables irqs, so use a
__slab_[un]lock() variant without irq disable there.
slab_[un]lock() thus needs a flags pointer parameter, which is unused on !RT.
free_debug_processing() now has two flags variables, which looks odd, but only
one is actually used - the one used in spin_lock_irqsave() on !RT and the one
used in slab_lock() on RT.
As a result, __cmpxchg_double_slab() and cmpxchg_double_slab() become
effectively identical on RT, as both will disable irqs, which is necessary on
RT as most callers of this function also rely on irqsaving lock operations.
Thus, assert that irqs are already disabled in __cmpxchg_double_slab() only on
!RT and also change the VM_BUG_ON assertion to the more standard lockdep_assert
one.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The variable object_map is protected by object_map_lock. The lock is always
acquired in debug code and within already atomic context
Make object_map_lock a raw_spinlock_t.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
flush_all() flushes a specific SLAB cache on each CPU (where the cache
is present). The deactivate_slab()/__free_slab() invocation happens
within IPI handler and is problematic for PREEMPT_RT.
The flush operation is not a frequent operation or a hot path. The
per-CPU flush operation can be moved to within a workqueue.
Because a workqueue handler, unlike IPI handler, does not disable irqs,
flush_slab() now has to disable them for working with the kmem_cache_cpu
fields. deactivate_slab() is safe to call with irqs enabled.
[vbabka@suse.cz: adapt to new SLUB changes]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
flush_slab() is called either as part IPI handler on given live cpu, or as a
cleanup on behalf of another cpu that went offline. The first case needs to
protect updating the kmem_cache_cpu fields with disabled irqs. Currently the
whole call happens with irqs disabled by the IPI handler, but the following
patch will change from IPI to workqueue, and flush_slab() will have to disable
irqs (to be replaced with a local lock later) in the critical part.
To prepare for this change, replace the call to flush_slab() for the dead cpu
handling with an opencoded variant that will not disable irqs nor take a local
lock.
Suggested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
slub_cpu_dead() cleans up for an offlined cpu from another cpu and calls only
functions that are now irq safe, so we don't need to disable irqs anymore.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
__unfreeze_partials() no longer needs to have irqs disabled, except for making
the spin_lock operations irq-safe, so convert the spin_locks operations and
remove the separate irq handling.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Unfreezing partial list can be split to two phases - detaching the list from
struct kmem_cache_cpu, and processing the list. The whole operation does not
need to be protected by disabled irqs. Restructure the code to separate the
detaching (with disabled irqs) and unfreezing (with irq disabling to be reduced
in the next patch).
Also, unfreeze_partials() can be called from another cpu on behalf of a cpu
that is being offlined, where disabling irqs on the local cpu has no sense, so
restructure the code as follows:
- __unfreeze_partials() is the bulk of unfreeze_partials() that processes the
detached percpu partial list
- unfreeze_partials() detaches list from current cpu with irqs disabled and
calls __unfreeze_partials()
- unfreeze_partials_cpu() is to be called for the offlined cpu so it needs no
irq disabling, and is called from __flush_cpu_slab()
- flush_cpu_slab() is for the local cpu thus it needs to call
unfreeze_partials(). So it can't simply call
__flush_cpu_slab(smp_processor_id()) anymore and we have to open-code the
proper calls.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Instead of iterating through the live percpu partial list, detach it from the
kmem_cache_cpu at once. This is simpler and will allow further optimization.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
unfreeze_partials() can be optimized so that it doesn't need irqs disabled for
the whole time. As the first step, move irq control into the function and
remove it from the put_cpu_partial() caller.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.
When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to
reenable them before deactivate_slab() we need to open-code flush_slab() in
___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields.
But that means a IRQ handler meanwhile might have assigned a new page to
kmem_cache_cpu.page so we have to retry the whole check.
The remaining callers of flush_slab() are the IPI handler which has disabled
irqs anyway, and slub_cpu_dead() which will be dealt with in the following
patch.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
dectivate_slab() now no longer touches the kmem_cache_cpu structure, so it will
be possible to call it with irqs enabled. Just convert the spin_lock calls to
their irq saving/restoring variants to make it irq-safe.
Note we now have to use cmpxchg_double_slab() for irq-safe slab_lock(), because
in some situations we don't take the list_lock, which would disable irqs.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
deactivate_slab() removes the cpu slab by merging the cpu freelist with slab's
freelist and putting the slab on the proper node's list. It also sets the
respective kmem_cache_cpu pointers to NULL.
By extracting the kmem_cache_cpu operations from the function, we can make it
not dependent on disabled irqs.
Also if we return a single free pointer from ___slab_alloc, we no longer have
to assign kmem_cache_cpu.page before deactivation or care if somebody preempted
us and assigned a different page to our kmem_cache_cpu in the process.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The function get_partial() does not need to have irqs disabled as a whole. It's
sufficient to convert spin_lock operations to their irq saving/restoring
versions.
As a result, it's now possible to reach the page allocator from the slab
allocator without disabling and re-enabling interrupts on the way.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Building on top of the previous patch, re-enable irqs before checking new
pages. alloc_debug_processing() is now called with enabled irqs so we need to
remove VM_BUG_ON(!irqs_disabled()); in check_slab() - there doesn't seem to be
a need for it anyway.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
When we obtain a new slab page from node partial list or page allocator, we
assign it to kmem_cache_cpu, perform some checks, and if they fail, we undo
the assignment.
In order to allow doing the checks without irq disabled, restructure the code
so that the checks are done first, and kmem_cache_cpu.page assignment only
after they pass.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
allocate_slab() currently re-enables irqs before calling to the page allocator.
It depends on gfpflags_allow_blocking() to determine if it's safe to do so.
Now we can instead simply restore irq before calling it through new_slab().
The other caller early_kmem_cache_node_alloc() is unaffected by this.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Continue reducing the irq disabled scope. Check for per-cpu partial slabs with
first with irqs enabled and then recheck with irqs disabled before grabbing
the slab page. Mostly preparatory for the following patches.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
SeongJae Park
