Juergen Gross noticed that commit f7f99100d8 ("mm: stop zeroing memory
during allocation in vmemmap") broke XEN PV domains when deferred struct
page initialization is enabled.
This is because the xen's PagePinned() flag is getting erased from
struct pages when they are initialized later in boot.
Juergen fixed this problem by disabling deferred pages on xen pv
domains. It is desirable, however, to have this feature available as it
reduces boot time. This fix re-enables the feature for pv-dmains, and
fixes the problem the following way:
The fix is to delay setting PagePinned flag until struct pages for all
allocated memory are initialized, i.e. until after free_all_bootmem().
A new x86_init.hyper op init_after_bootmem() is called to let xen know
that boot allocator is done, and hence struct pages for all the
allocated memory are now initialized. If deferred page initialization
is enabled, the rest of struct pages are going to be initialized later
in boot once page_alloc_init_late() is called.
xen_after_bootmem() walks page table's pages and marks them pinned.
Link: http://lkml.kernel.org/r/20180226160112.24724-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jia Zhang <zhang.jia@linux.alibaba.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, all reserved pages for CMA region are belong to the ZONE_MOVABLE
and it only serves for a request with GFP_HIGHMEM && GFP_MOVABLE.
Therefore, we don't need to maintain ALLOC_CMA at all.
Link: http://lkml.kernel.org/r/1512114786-5085-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/cma: manage the memory of the CMA area by using the
ZONE_MOVABLE", v2.
0. History
This patchset is the follow-up of the discussion about the "Introduce
ZONE_CMA (v7)" [1]. Please reference it if more information is needed.
1. What does this patch do?
This patch changes the management way for the memory of the CMA area in
the MM subsystem. Currently the memory of the CMA area is managed by
the zone where their pfn is belong to. However, this approach has some
problems since MM subsystem doesn't have enough logic to handle the
situation that different characteristic memories are in a single zone.
To solve this issue, this patch try to manage all the memory of the CMA
area by using the MOVABLE zone. In MM subsystem's point of view,
characteristic of the memory on the MOVABLE zone and the memory of the
CMA area are the same. So, managing the memory of the CMA area by using
the MOVABLE zone will not have any problem.
2. Motivation
There are some problems with current approach. See following. Although
these problem would not be inherent and it could be fixed without this
conception change, it requires many hooks addition in various code path
and it would be intrusive to core MM and would be really error-prone.
Therefore, I try to solve them with this new approach. Anyway,
following is the problems of the current implementation.
o CMA memory utilization
First, following is the freepage calculation logic in MM.
- For movable allocation: freepage = total freepage
- For unmovable allocation: freepage = total freepage - CMA freepage
Freepages on the CMA area is used after the normal freepages in the zone
where the memory of the CMA area is belong to are exhausted. At that
moment that the number of the normal freepages is zero, so
- For movable allocation: freepage = total freepage = CMA freepage
- For unmovable allocation: freepage = 0
If unmovable allocation comes at this moment, allocation request would
fail to pass the watermark check and reclaim is started. After reclaim,
there would exist the normal freepages so freepages on the CMA areas
would not be used.
FYI, there is another attempt [2] trying to solve this problem in lkml.
And, as far as I know, Qualcomm also has out-of-tree solution for this
problem.
Useless reclaim:
There is no logic to distinguish CMA pages in the reclaim path. Hence,
CMA page is reclaimed even if the system just needs the page that can be
usable for the kernel allocation.
Atomic allocation failure:
This is also related to the fallback allocation policy for the memory of
the CMA area. Consider the situation that the number of the normal
freepages is *zero* since the bunch of the movable allocation requests
come. Kswapd would not be woken up due to following freepage
calculation logic.
- For movable allocation: freepage = total freepage = CMA freepage
If atomic unmovable allocation request comes at this moment, it would
fails due to following logic.
- For unmovable allocation: freepage = total freepage - CMA freepage = 0
It was reported by Aneesh [3].
Useless compaction:
Usual high-order allocation request is unmovable allocation request and
it cannot be served from the memory of the CMA area. In compaction,
migration scanner try to migrate the page in the CMA area and make
high-order page there. As mentioned above, it cannot be usable for the
unmovable allocation request so it's just waste.
3. Current approach and new approach
Current approach is that the memory of the CMA area is managed by the
zone where their pfn is belong to. However, these memory should be
distinguishable since they have a strong limitation. So, they are
marked as MIGRATE_CMA in pageblock flag and handled specially. However,
as mentioned in section 2, the MM subsystem doesn't have enough logic to
deal with this special pageblock so many problems raised.
New approach is that the memory of the CMA area is managed by the
MOVABLE zone. MM already have enough logic to deal with special zone
like as HIGHMEM and MOVABLE zone. So, managing the memory of the CMA
area by the MOVABLE zone just naturally work well because constraints
for the memory of the CMA area that the memory should always be
migratable is the same with the constraint for the MOVABLE zone.
There is one side-effect for the usability of the memory of the CMA
area. The use of MOVABLE zone is only allowed for a request with
GFP_HIGHMEM && GFP_MOVABLE so now the memory of the CMA area is also
only allowed for this gfp flag. Before this patchset, a request with
GFP_MOVABLE can use them. IMO, It would not be a big issue since most
of GFP_MOVABLE request also has GFP_HIGHMEM flag. For example, file
cache page and anonymous page. However, file cache page for blockdev
file is an exception. Request for it has no GFP_HIGHMEM flag. There is
pros and cons on this exception. In my experience, blockdev file cache
pages are one of the top reason that causes cma_alloc() to fail
temporarily. So, we can get more guarantee of cma_alloc() success by
discarding this case.
Note that there is no change in admin POV since this patchset is just
for internal implementation change in MM subsystem. Just one minor
difference for admin is that the memory stat for CMA area will be
printed in the MOVABLE zone. That's all.
4. Result
Following is the experimental result related to utilization problem.
8 CPUs, 1024 MB, VIRTUAL MACHINE
make -j16
<Before>
CMA area: 0 MB 512 MB
Elapsed-time: 92.4 186.5
pswpin: 82 18647
pswpout: 160 69839
<After>
CMA : 0 MB 512 MB
Elapsed-time: 93.1 93.4
pswpin: 84 46
pswpout: 183 92
akpm: "kernel test robot" reported a 26% improvement in
vm-scalability.throughput:
http://lkml.kernel.org/r/20180330012721.GA3845@yexl-desktop
[1]: lkml.kernel.org/r/1491880640-9944-1-git-send-email-iamjoonsoo.kim@lge.com
[2]: https://lkml.org/lkml/2014/10/15/623
[3]: http://www.spinics.net/lists/linux-mm/msg100562.html
Link: http://lkml.kernel.org/r/1512114786-5085-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that
important to reserve. When ZONE_MOVABLE is used, this problem would
theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE
allocation request which is mainly used for page cache and anon page
allocation. So, fix it by setting 0 to
sysctl_lowmem_reserve_ratio[ZONE_HIGHMEM].
And, defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES - 1 size
makes code complex. For example, if there is highmem system, following
reserve ratio is activated for *NORMAL ZONE* which would be easyily
misleading people.
#ifdef CONFIG_HIGHMEM
32
#endif
This patch also fixes this situation by defining
sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES and place "#ifdef" to
right place.
Link: http://lkml.kernel.org/r/1504672525-17915-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Tony Lindgren <tony@atomide.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Adjust /proc/meminfo MemAvailable calculation by adding the amount of
indirectly reclaimable memory (rounded to the PAGE_SIZE).
Link: http://lkml.kernel.org/r/20180305133743.12746-4-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
start_isolate_page_range() is used to set the migrate type of a set of
pageblocks to MIGRATE_ISOLATE while attempting to start a migration
operation. It assumes that only one thread is calling it for the
specified range. This routine is used by CMA, memory hotplug and
gigantic huge pages. Each of these users synchronize access to the
range within their subsystem. However, two subsystems (CMA and gigantic
huge pages for example) could attempt operations on the same range. If
this happens, one thread may 'undo' the work another thread is doing.
This can result in pageblocks being incorrectly left marked as
MIGRATE_ISOLATE and therefore not available for page allocation.
What is ideally needed is a way to synchronize access to a set of
pageblocks that are undergoing isolation and migration. The only thing
we know about these pageblocks is that they are all in the same zone. A
per-node mutex is too coarse as we want to allow multiple operations on
different ranges within the same zone concurrently. Instead, we will
use the migration type of the pageblocks themselves as a form of
synchronization.
start_isolate_page_range sets the migration type on a set of page-
blocks going in order from the one associated with the smallest pfn to
the largest pfn. The zone lock is acquired to check and set the
migration type. When going through the list of pageblocks check if
MIGRATE_ISOLATE is already set. If so, this indicates another thread is
working on this pageblock. We know exactly which pageblocks we set, so
clean up by undo those and return -EBUSY.
This allows start_isolate_page_range to serve as a synchronization
mechanism and will allow for more general use of callers making use of
these interfaces. Update comments in alloc_contig_range to reflect this
new functionality.
Each CPU holds the associated zone lock to modify or examine the
migration type of a pageblock. And, it will only examine/update a
single pageblock per lock acquire/release cycle.
Link: http://lkml.kernel.org/r/20180309224731.16978-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kswapd will not wakeup if per-zone watermarks are not failing or if too
many previous attempts at background reclaim have failed.
This can be true if there is a lot of free memory available. For high-
order allocations, kswapd is responsible for waking up kcompactd for
background compaction. If the zone is not below its watermarks or
reclaim has recently failed (lots of free memory, nothing left to
reclaim), kcompactd does not get woken up.
When __GFP_DIRECT_RECLAIM is not allowed, allow kcompactd to still be
woken up even if kswapd will not reclaim. This allows high-order
allocations, such as thp, to still trigger background compaction even
when the zone has an abundance of free memory.
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803111659420.209721@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a page is freed back to the global pool, its buddy will be checked
to see if it's possible to do a merge. This requires accessing buddy's
page structure and that access could take a long time if it's cache
cold.
This patch adds a prefetch to the to-be-freed page's buddy outside of
zone->lock in hope of accessing buddy's page structure later under
zone->lock will be faster. Since we *always* do buddy merging and check
an order-0 page's buddy to try to merge it when it goes into the main
allocator, the cacheline will always come in, i.e. the prefetched data
will never be unused.
Normally, the number of prefetch will be pcp->batch(default=31 and has
an upper limit of (PAGE_SHIFT * 8)=96 on x86_64) but in the case of
pcp's pages get all drained, it will be pcp->count which has an upper
limit of pcp->high. pcp->high, although has a default value of 186
(pcp->batch=31 * 6), can be changed by user through
/proc/sys/vm/percpu_pagelist_fraction and there is no software upper
limit so could be large, like several thousand. For this reason, only
the first pcp->batch number of page's buddy structure is prefetched to
avoid excessive prefetching.
In the meantime, there are two concerns:
1. the prefetch could potentially evict existing cachelines, especially
for L1D cache since it is not huge
2. there is some additional instruction overhead, namely calculating
buddy pfn twice
For 1, it's hard to say, this microbenchmark though shows good result
but the actual benefit of this patch will be workload/CPU dependant;
For 2, since the calculation is a XOR on two local variables, it's
expected in many cases that cycles spent will be offset by reduced
memory latency later. This is especially true for NUMA machines where
multiple CPUs are contending on zone->lock and the most time consuming
part under zone->lock is the wait of 'struct page' cacheline of the
to-be-freed pages and their buddies.
Test with will-it-scale/page_fault1 full load:
kernel Broadwell(2S) Skylake(2S) Broadwell(4S) Skylake(4S)
v4.16-rc2+ 9034215 7971818 13667135 15677465
patch2/3 9536374 +5.6% 8314710 +4.3% 14070408 +3.0% 16675866 +6.4%
this patch 10180856 +6.8% 8506369 +2.3% 14756865 +4.9% 17325324 +3.9%
Note: this patch's performance improvement percent is against patch2/3.
(Changelog stolen from Dave Hansen and Mel Gorman's comments at
http://lkml.kernel.org/r/148a42d8-8306-2f2f-7f7c-86bc118f8ccd@intel.com)
[aaron.lu@intel.com: use helper function, avoid disordering pages]
Link: http://lkml.kernel.org/r/20180301062845.26038-4-aaron.lu@intel.com
Link: http://lkml.kernel.org/r/20180320113146.GB24737@intel.com
[aaron.lu@intel.com: v4]
Link: http://lkml.kernel.org/r/20180301062845.26038-4-aaron.lu@intel.com
Link: http://lkml.kernel.org/r/20180309082431.GB30868@intel.com
Link: http://lkml.kernel.org/r/20180301062845.26038-4-aaron.lu@intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Suggested-by: Ying Huang <ying.huang@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When freeing a batch of pages from Per-CPU-Pages(PCP) back to buddy, the
zone->lock is held and then pages are chosen from PCP's migratetype
list. While there is actually no need to do this 'choose part' under
lock since it's PCP pages, the only CPU that can touch them is us and
irq is also disabled.
Moving this part outside could reduce lock held time and improve
performance. Test with will-it-scale/page_fault1 full load:
kernel Broadwell(2S) Skylake(2S) Broadwell(4S) Skylake(4S)
v4.16-rc2+ 9034215 7971818 13667135 15677465
this patch 9536374 +5.6% 8314710 +4.3% 14070408 +3.0% 16675866 +6.4%
What the test does is: starts $nr_cpu processes and each will repeatedly
do the following for 5 minutes:
- mmap 128M anonymouse space
- write access to that space
- munmap.
The score is the aggregated iteration.
https://github.com/antonblanchard/will-it-scale/blob/master/tests/page_fault1.c
Link: http://lkml.kernel.org/r/20180301062845.26038-3-aaron.lu@intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.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>
Matthew Wilcox found that all callers of free_pcppages_bulk() currently
update pcp->count immediately after so it's natural to do it inside
free_pcppages_bulk().
No functionality or performance change is expected from this patch.
Link: http://lkml.kernel.org/r/20180301062845.26038-2-aaron.lu@intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.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>
mirrored_kernelcore can be in __meminitdata, so move it there.
At the same time, fixup section specifiers to be after the name of the
variable per checkpatch.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802121623280.179479@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both kernelcore= and movablecore= can be used to define the amount of
ZONE_NORMAL and ZONE_MOVABLE on a system, respectively. This requires
the system memory capacity to be known when specifying the command line,
however.
This introduces the ability to define both kernelcore= and movablecore=
as a percentage of total system memory. This is convenient for systems
software that wants to define the amount of ZONE_MOVABLE, for example,
as a proportion of a system's memory rather than a hardcoded byte value.
To define the percentage, the final character of the parameter should be
a '%'.
mhocko: "why is anyone using these options nowadays?"
rientjes:
:
: Fragmentation of non-__GFP_MOVABLE pages due to low on memory
: situations can pollute most pageblocks on the system, as much as 1GB of
: slab being fragmented over 128GB of memory, for example. When the
: amount of kernel memory is well bounded for certain systems, it is
: better to aggressively reclaim from existing MIGRATE_UNMOVABLE
: pageblocks rather than eagerly fallback to others.
:
: We have additional patches that help with this fragmentation if you're
: interested, specifically kcompactd compaction of MIGRATE_UNMOVABLE
: pageblocks triggered by fallback of non-__GFP_MOVABLE allocations and
: draining of pcp lists back to the zone free area to prevent stranding.
[rientjes@google.com: updates]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802131700160.71590@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802121622470.179479@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During memory hotplugging we traverse struct pages three times:
1. memset(0) in sparse_add_one_section()
2. loop in __add_section() to set do: set_page_node(page, nid); and
SetPageReserved(page);
3. loop in memmap_init_zone() to call __init_single_pfn()
This patch removes the first two loops, and leaves only loop 3. All
struct pages are initialized in one place, the same as it is done during
boot.
The benefits:
- We improve memory hotplug performance because we are not evicting the
cache several times and also reduce loop branching overhead.
- Remove condition from hotpath in __init_single_pfn(), that was added
in order to fix the problem that was reported by Bharata in the above
email thread, thus also improve performance during normal boot.
- Make memory hotplug more similar to the boot memory initialization
path because we zero and initialize struct pages only in one
function.
- Simplifies memory hotplug struct page initialization code, and thus
enables future improvements, such as multi-threading the
initialization of struct pages in order to improve hotplug
performance even further on larger machines.
[pasha.tatashin@oracle.com: v5]
Link: http://lkml.kernel.org/r/20180228030308.1116-7-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180215165920.8570-7-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Deferred page initialization allows the boot cpu to initialize a small
subset of the system's pages early in boot, with other cpus doing the
rest later on.
It is, however, problematic to know how many pages the kernel needs
during boot. Different modules and kernel parameters may change the
requirement, so the boot cpu either initializes too many pages or runs
out of memory.
To fix that, initialize early pages on demand. This ensures the kernel
does the minimum amount of work to initialize pages during boot and
leaves the rest to be divided in the multithreaded initialization path
(deferred_init_memmap).
The on-demand code is permanently disabled using static branching once
deferred pages are initialized. After the static branch is changed to
false, the overhead is up-to two branch-always instructions if the zone
watermark check fails or if rmqueue fails.
Sergey Senozhatsky noticed that while deferred pages currently make
sense only on NUMA machines (we start one thread per latency node),
CONFIG_NUMA is not a requirement for CONFIG_DEFERRED_STRUCT_PAGE_INIT,
so that is also must be addressed in the patch.
[akpm@linux-foundation.org: fix typo in comment, make deferred_pages static]
[pasha.tatashin@oracle.com: fix min() type mismatch warning]
Link: http://lkml.kernel.org/r/20180212164543.26592-1-pasha.tatashin@oracle.com
[pasha.tatashin@oracle.com: use zone_to_nid() in deferred_grow_zone()]
Link: http://lkml.kernel.org/r/20180214163343.21234-2-pasha.tatashin@oracle.com
[pasha.tatashin@oracle.com: might_sleep warning]
Link: http://lkml.kernel.org/r/20180306192022.28289-1-pasha.tatashin@oracle.com
[akpm@linux-foundation.org: s/spin_lock/spin_lock_irq/ in page_alloc_init_late()]
[pasha.tatashin@oracle.com: v5]
Link: http://lkml.kernel.org/r/20180309220807.24961-3-pasha.tatashin@oracle.com
[akpm@linux-foundation.org: tweak comments]
[pasha.tatashin@oracle.com: v6]
Link: http://lkml.kernel.org/r/20180313182355.17669-3-pasha.tatashin@oracle.com
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20180209192216.20509-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Miles Chen <miles.chen@mediatek.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Vlastimil Babka reported about a window issue during which when deferred
pages are initialized, and the current version of on-demand
initialization is finished, allocations may fail. While this is highly
unlikely scenario, since this kind of allocation request must be large,
and must come from interrupt handler, we still want to cover it.
We solve this by initializing deferred pages with interrupts disabled,
and holding node_size_lock spin lock while pages in the node are being
initialized. The on-demand deferred page initialization that comes
later will use the same lock, and thus synchronize with
deferred_init_memmap().
It is unlikely for threads that initialize deferred pages to be
interrupted. They run soon after smp_init(), but before modules are
initialized, and long before user space programs. This is why there is
no adverse effect of having these threads running with interrupts
disabled.
[pasha.tatashin@oracle.com: v6]
Link: http://lkml.kernel.org/r/20180313182355.17669-2-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180309220807.24961-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Miles Chen <miles.chen@mediatek.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
alloc_contig_range() initiates compaction and eventual migration for the
purpose of either CMA or HugeTLB allocations. At present, the reason
code remains the same MR_CMA for either of these cases. Let's make it
MR_CONTIG_RANGE which will appropriately reflect the reason code in both
these cases.
Link: http://lkml.kernel.org/r/20180202091518.18798-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This removes the entire architecture code for blackfin, cris, frv, m32r,
metag, mn10300, score, and tile, including the associated device drivers.
I have been working with the (former) maintainers for each one to ensure
that my interpretation was right and the code is definitely unused in
mainline kernels. Many had fond memories of working on the respective
ports to start with and getting them included in upstream, but also saw
no point in keeping the port alive without any users.
In the end, it seems that while the eight architectures are extremely
different, they all suffered the same fate: There was one company
in charge of an SoC line, a CPU microarchitecture and a software
ecosystem, which was more costly than licensing newer off-the-shelf
CPU cores from a third party (typically ARM, MIPS, or RISC-V). It seems
that all the SoC product lines are still around, but have not used the
custom CPU architectures for several years at this point. In contrast,
CPU instruction sets that remain popular and have actively maintained
kernel ports tend to all be used across multiple licensees.
The removal came out of a discussion that is now documented at
https://lwn.net/Articles/748074/. Unlike the original plans, I'm not
marking any ports as deprecated but remove them all at once after I made
sure that they are all unused. Some architectures (notably tile, mn10300,
and blackfin) are still being shipped in products with old kernels,
but those products will never be updated to newer kernel releases.
After this series, we still have a few architectures without mainline
gcc support:
- unicore32 and hexagon both have very outdated gcc releases, but the
maintainers promised to work on providing something newer. At least
in case of hexagon, this will only be llvm, not gcc.
- openrisc, risc-v and nds32 are still in the process of finishing their
support or getting it added to mainline gcc in the first place.
They all have patched gcc-7.3 ports that work to some degree, but
complete upstream support won't happen before gcc-8.1. Csky posted
their first kernel patch set last week, their situation will be similar.
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Merge tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pul removal of obsolete architecture ports from Arnd Bergmann:
"This removes the entire architecture code for blackfin, cris, frv,
m32r, metag, mn10300, score, and tile, including the associated device
drivers.
I have been working with the (former) maintainers for each one to
ensure that my interpretation was right and the code is definitely
unused in mainline kernels. Many had fond memories of working on the
respective ports to start with and getting them included in upstream,
but also saw no point in keeping the port alive without any users.
In the end, it seems that while the eight architectures are extremely
different, they all suffered the same fate: There was one company in
charge of an SoC line, a CPU microarchitecture and a software
ecosystem, which was more costly than licensing newer off-the-shelf
CPU cores from a third party (typically ARM, MIPS, or RISC-V). It
seems that all the SoC product lines are still around, but have not
used the custom CPU architectures for several years at this point. In
contrast, CPU instruction sets that remain popular and have actively
maintained kernel ports tend to all be used across multiple licensees.
[ See the new nds32 port merged in the previous commit for the next
generation of "one company in charge of an SoC line, a CPU
microarchitecture and a software ecosystem" - Linus ]
The removal came out of a discussion that is now documented at
https://lwn.net/Articles/748074/. Unlike the original plans, I'm not
marking any ports as deprecated but remove them all at once after I
made sure that they are all unused. Some architectures (notably tile,
mn10300, and blackfin) are still being shipped in products with old
kernels, but those products will never be updated to newer kernel
releases.
After this series, we still have a few architectures without mainline
gcc support:
- unicore32 and hexagon both have very outdated gcc releases, but the
maintainers promised to work on providing something newer. At least
in case of hexagon, this will only be llvm, not gcc.
- openrisc, risc-v and nds32 are still in the process of finishing
their support or getting it added to mainline gcc in the first
place. They all have patched gcc-7.3 ports that work to some
degree, but complete upstream support won't happen before gcc-8.1.
Csky posted their first kernel patch set last week, their situation
will be similar
[ Palmer Dabbelt points out that RISC-V support is in mainline gcc
since gcc-7, although gcc-7.3.0 is the recommended minimum - Linus ]"
This really says it all:
2498 files changed, 95 insertions(+), 467668 deletions(-)
* tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (74 commits)
MAINTAINERS: UNICORE32: Change email account
staging: iio: remove iio-trig-bfin-timer driver
tty: hvc: remove tile driver
tty: remove bfin_jtag_comm and hvc_bfin_jtag drivers
serial: remove tile uart driver
serial: remove m32r_sio driver
serial: remove blackfin drivers
serial: remove cris/etrax uart drivers
usb: Remove Blackfin references in USB support
usb: isp1362: remove blackfin arch glue
usb: musb: remove blackfin port
usb: host: remove tilegx platform glue
pwm: remove pwm-bfin driver
i2c: remove bfin-twi driver
spi: remove blackfin related host drivers
watchdog: remove bfin_wdt driver
can: remove bfin_can driver
mmc: remove bfin_sdh driver
input: misc: remove blackfin rotary driver
input: keyboard: remove bf54x driver
...
Dave Jones reported fs_reclaim lockdep warnings.
============================================
WARNING: possible recursive locking detected
4.15.0-rc9-backup-debug+ #1 Not tainted
--------------------------------------------
sshd/24800 is trying to acquire lock:
(fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
but task is already holding lock:
(fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(fs_reclaim);
lock(fs_reclaim);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by sshd/24800:
#0: (sk_lock-AF_INET6){+.+.}, at: [<000000001a069652>] tcp_sendmsg+0x19/0x40
#1: (fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
stack backtrace:
CPU: 3 PID: 24800 Comm: sshd Not tainted 4.15.0-rc9-backup-debug+ #1
Call Trace:
dump_stack+0xbc/0x13f
__lock_acquire+0xa09/0x2040
lock_acquire+0x12e/0x350
fs_reclaim_acquire.part.102+0x29/0x30
kmem_cache_alloc+0x3d/0x2c0
alloc_extent_state+0xa7/0x410
__clear_extent_bit+0x3ea/0x570
try_release_extent_mapping+0x21a/0x260
__btrfs_releasepage+0xb0/0x1c0
btrfs_releasepage+0x161/0x170
try_to_release_page+0x162/0x1c0
shrink_page_list+0x1d5a/0x2fb0
shrink_inactive_list+0x451/0x940
shrink_node_memcg.constprop.88+0x4c9/0x5e0
shrink_node+0x12d/0x260
try_to_free_pages+0x418/0xaf0
__alloc_pages_slowpath+0x976/0x1790
__alloc_pages_nodemask+0x52c/0x5c0
new_slab+0x374/0x3f0
___slab_alloc.constprop.81+0x47e/0x5a0
__slab_alloc.constprop.80+0x32/0x60
__kmalloc_track_caller+0x267/0x310
__kmalloc_reserve.isra.40+0x29/0x80
__alloc_skb+0xee/0x390
sk_stream_alloc_skb+0xb8/0x340
tcp_sendmsg_locked+0x8e6/0x1d30
tcp_sendmsg+0x27/0x40
inet_sendmsg+0xd0/0x310
sock_write_iter+0x17a/0x240
__vfs_write+0x2ab/0x380
vfs_write+0xfb/0x260
SyS_write+0xb6/0x140
do_syscall_64+0x1e5/0xc05
entry_SYSCALL64_slow_path+0x25/0x25
This warning is caused by commit d92a8cfcb3 ("locking/lockdep:
Rework FS_RECLAIM annotation") which replaced the use of
lockdep_{set,clear}_current_reclaim_state() in __perform_reclaim()
and lockdep_trace_alloc() in slab_pre_alloc_hook() with
fs_reclaim_acquire()/ fs_reclaim_release().
Since __kmalloc_reserve() from __alloc_skb() adds __GFP_NOMEMALLOC |
__GFP_NOWARN to gfp_mask, and all reclaim path simply propagates
__GFP_NOMEMALLOC, fs_reclaim_acquire() in slab_pre_alloc_hook() is
trying to grab the 'fake' lock again when __perform_reclaim() already
grabbed the 'fake' lock.
The
/* this guy won't enter reclaim */
if ((current->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
return false;
test which causes slab_pre_alloc_hook() to try to grab the 'fake' lock
was added by commit cf40bd16fd ("lockdep: annotate reclaim context
(__GFP_NOFS)"). But that test is outdated because PF_MEMALLOC thread
won't enter reclaim regardless of __GFP_NOMEMALLOC after commit
341ce06f69 ("page allocator: calculate the alloc_flags for allocation
only once") added the PF_MEMALLOC safeguard (
/* Avoid recursion of direct reclaim */
if (p->flags & PF_MEMALLOC)
goto nopage;
in __alloc_pages_slowpath()).
Thus, let's fix outdated test by removing __GFP_NOMEMALLOC test and
allow __need_fs_reclaim() to return false.
Link: http://lkml.kernel.org/r/201802280650.FJC73911.FOSOMLJVFFQtHO@I-love.SAKURA.ne.jp
Fixes: d92a8cfcb3 ("locking/lockdep: Rework FS_RECLAIM annotation")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Tested-by: Dave Jones <davej@codemonkey.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org> [4.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tile was the only remaining architecture to implement alloc_remap(),
and since that is being removed, there is no point in keeping this
function.
Removing all callers simplifies the mem_map handling.
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This reverts commit 864b75f9d6.
Commit 864b75f9d6 ("mm/page_alloc: fix memmap_init_zone pageblock
alignment") modified the logic in memmap_init_zone() to initialize
struct pages associated with invalid PFNs, to appease a VM_BUG_ON()
in move_freepages(), which is redundant by its own admission, and
dereferences struct page fields to obtain the zone without checking
whether the struct pages in question are valid to begin with.
Commit 864b75f9d6 only makes it worse, since the rounding it does
may cause pfn assume the same value it had in a prior iteration of
the loop, resulting in an infinite loop and a hang very early in the
boot. Also, since it doesn't perform the same rounding on start_pfn
itself but only on intermediate values following an invalid PFN, we
may still hit the same VM_BUG_ON() as before.
So instead, let's fix this at the core, and ensure that the BUG
check doesn't dereference struct page fields of invalid pages.
Fixes: 864b75f9d6 ("mm/page_alloc: fix memmap_init_zone pageblock alignment")
Tested-by: Jan Glauber <jglauber@cavium.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Cc: Daniel Vacek <neelx@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit b92df1de5d ("mm: page_alloc: skip over regions of invalid pfns
where possible") introduced a bug where move_freepages() triggers a
VM_BUG_ON() on uninitialized page structure due to pageblock alignment.
To fix this, simply align the skipped pfns in memmap_init_zone() the
same way as in move_freepages_block().
Seen in one of the RHEL reports:
crash> log | grep -e BUG -e RIP -e Call.Trace -e move_freepages_block -e rmqueue -e freelist -A1
kernel BUG at mm/page_alloc.c:1389!
invalid opcode: 0000 [#1] SMP
--
RIP: 0010:[<ffffffff8118833e>] [<ffffffff8118833e>] move_freepages+0x15e/0x160
RSP: 0018:ffff88054d727688 EFLAGS: 00010087
--
Call Trace:
[<ffffffff811883b3>] move_freepages_block+0x73/0x80
[<ffffffff81189e63>] __rmqueue+0x263/0x460
[<ffffffff8118c781>] get_page_from_freelist+0x7e1/0x9e0
[<ffffffff8118caf6>] __alloc_pages_nodemask+0x176/0x420
--
RIP [<ffffffff8118833e>] move_freepages+0x15e/0x160
RSP <ffff88054d727688>
crash> page_init_bug -v | grep RAM
<struct resource 0xffff88067fffd2f8> 1000 - 9bfff System RAM (620.00 KiB)
<struct resource 0xffff88067fffd3a0> 100000 - 430bffff System RAM ( 1.05 GiB = 1071.75 MiB = 1097472.00 KiB)
<struct resource 0xffff88067fffd410> 4b0c8000 - 4bf9cfff System RAM ( 14.83 MiB = 15188.00 KiB)
<struct resource 0xffff88067fffd480> 4bfac000 - 646b1fff System RAM (391.02 MiB = 400408.00 KiB)
<struct resource 0xffff88067fffd560> 7b788000 - 7b7fffff System RAM (480.00 KiB)
<struct resource 0xffff88067fffd640> 100000000 - 67fffffff System RAM ( 22.00 GiB)
crash> page_init_bug | head -6
<struct resource 0xffff88067fffd560> 7b788000 - 7b7fffff System RAM (480.00 KiB)
<struct page 0xffffea0001ede200> 1fffff00000000 0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32 4096 1048575
<struct page 0xffffea0001ede200> 505736 505344 <struct page 0xffffea0001ed8000> 505855 <struct page 0xffffea0001edffc0>
<struct page 0xffffea0001ed8000> 0 0 <struct pglist_data 0xffff88047ffd9000> 0 <struct zone 0xffff88047ffd9000> DMA 1 4095
<struct page 0xffffea0001edffc0> 1fffff00000400 0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32 4096 1048575
BUG, zones differ!
Note that this range follows two not populated sections
68000000-77ffffff in this zone. 7b788000-7b7fffff is the first one
after a gap. This makes memmap_init_zone() skip all the pfns up to the
beginning of this range. But this range is not pageblock (2M) aligned.
In fact no range has to be.
crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b787000 7b788000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffea0001e00000 78000000 0 0 0 0
ffffea0001ed7fc0 7b5ff000 0 0 0 0
ffffea0001ed8000 7b600000 0 0 0 0 <<<<
ffffea0001ede1c0 7b787000 0 0 0 0
ffffea0001ede200 7b788000 0 0 1 1fffff00000000
Top part of page flags should contain nodeid and zonenr, which is not
the case for page ffffea0001ed8000 here (<<<<).
crash> log | grep -o fffea0001ed[^\ ]* | sort -u
fffea0001ed8000
fffea0001eded20
fffea0001edffc0
crash> bt -r | grep -o fffea0001ed[^\ ]* | sort -u
fffea0001ed8000
fffea0001eded00
fffea0001eded20
fffea0001edffc0
Initialization of the whole beginning of the section is skipped up to
the start of the range due to the commit b92df1de5d. Now any code
calling move_freepages_block() (like reusing the page from a freelist as
in this example) with a page from the beginning of the range will get
the page rounded down to start_page ffffea0001ed8000 and passed to
move_freepages() which crashes on assertion getting wrong zonenr.
> VM_BUG_ON(page_zone(start_page) != page_zone(end_page));
Note, page_zone() derives the zone from page flags here.
From similar machine before commit b92df1de5d28:
crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b7fe000 7b7ff000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffff73941e00000 78000000 0 0 1 1fffff00000000
fffff73941ed7fc0 7b5ff000 0 0 1 1fffff00000000
fffff73941ed8000 7b600000 0 0 1 1fffff00000000
fffff73941edff80 7b7fe000 0 0 1 1fffff00000000
fffff73941edffc0 7b7ff000 ffff8e67e04d3ae0 ad84 1 1fffff00020068 uptodate,lru,active,mappedtodisk
All the pages since the beginning of the section are initialized.
move_freepages()' not gonna blow up.
The same machine with this fix applied:
crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b7fe000 7b7ff000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffea0001e00000 78000000 0 0 0 0
ffffea0001e00000 7b5ff000 0 0 0 0
ffffea0001ed8000 7b600000 0 0 1 1fffff00000000
ffffea0001edff80 7b7fe000 0 0 1 1fffff00000000
ffffea0001edffc0 7b7ff000 ffff88017fb13720 8 2 1fffff00020068 uptodate,lru,active,mappedtodisk
At least the bare minimum of pages is initialized preventing the crash
as well.
Customers started to report this as soon as 7.4 (where b92df1de5d was
merged in RHEL) was released. I remember reports from
September/October-ish times. It's not easily reproduced and happens on
a handful of machines only. I guess that's why. But that does not make
it less serious, I think.
Though there actually is a report here:
https://bugzilla.kernel.org/show_bug.cgi?id=196443
And there are reports for Fedora from July:
https://bugzilla.redhat.com/show_bug.cgi?id=1473242
and CentOS:
https://bugs.centos.org/view.php?id=13964
and we internally track several dozens reports for RHEL bug
https://bugzilla.redhat.com/show_bug.cgi?id=1525121
Link: http://lkml.kernel.org/r/0485727b2e82da7efbce5f6ba42524b429d0391a.1520011945.git.neelx@redhat.com
Fixes: b92df1de5d ("mm: page_alloc: skip over regions of invalid pfns where possible")
Signed-off-by: Daniel Vacek <neelx@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.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>
Commit f7f99100d8 ("mm: stop zeroing memory during allocation in
vmemmap") broke Xen pv domains in some configurations, as the "Pinned"
information in struct page of early page tables could get lost.
This will lead to the kernel trying to write directly into the page
tables instead of asking the hypervisor to do so. The result is a crash
like the following:
BUG: unable to handle kernel paging request at ffff8801ead19008
IP: xen_set_pud+0x4e/0xd0
PGD 1c0a067 P4D 1c0a067 PUD 23a0067 PMD 1e9de0067 PTE 80100001ead19065
Oops: 0003 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-default+ #271
Hardware name: Dell Inc. Latitude E6440/0159N7, BIOS A07 06/26/2014
task: ffffffff81c10480 task.stack: ffffffff81c00000
RIP: e030:xen_set_pud+0x4e/0xd0
Call Trace:
__pmd_alloc+0x128/0x140
ioremap_page_range+0x3f4/0x410
__ioremap_caller+0x1c3/0x2e0
acpi_os_map_iomem+0x175/0x1b0
acpi_tb_acquire_table+0x39/0x66
acpi_tb_validate_table+0x44/0x7c
acpi_tb_verify_temp_table+0x45/0x304
acpi_reallocate_root_table+0x12d/0x141
acpi_early_init+0x4d/0x10a
start_kernel+0x3eb/0x4a1
xen_start_kernel+0x528/0x532
Code: 48 01 e8 48 0f 42 15 a2 fd be 00 48 01 d0 48 ba 00 00 00 00 00 ea ff ff 48 c1 e8 0c 48 c1 e0 06 48 01 d0 48 8b 00 f6 c4 02 75 5d <4c> 89 65 00 5b 5d 41 5c c3 65 8b 05 52 9f fe 7e 89 c0 48 0f a3
RIP: xen_set_pud+0x4e/0xd0 RSP: ffffffff81c03cd8
CR2: ffff8801ead19008
---[ end trace 38eca2e56f1b642e ]---
Avoid this problem by not deferring struct page initialization when
running as Xen pv guest.
Pavel said:
: This is unique for Xen, so this particular issue won't effect other
: configurations. I am going to investigate if there is a way to
: re-enable deferred page initialization on xen guests.
[akpm@linux-foundation.org: explicitly include xen.h]
Link: http://lkml.kernel.org/r/20180216154101.22865-1-jgross@suse.com
Fixes: f7f99100d8 ("mm: stop zeroing memory during allocation in vmemmap")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Bob Picco <bob.picco@oracle.com>
Cc: <stable@vger.kernel.org> [4.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Require struct page by default for filesystem DAX to remove a number of
surprising failure cases. This includes failures with direct I/O, gdb and
fork(2).
* Add support for the new Platform Capabilities Structure added to the NFIT in
ACPI 6.2a. This new table tells us whether the platform supports flushing
of CPU and memory controller caches on unexpected power loss events.
* Revamp vmem_altmap and dev_pagemap handling to clean up code and better
support future future PCI P2P uses.
* Deprecate the ND_IOCTL_SMART_THRESHOLD command whose payload has become
out-of-sync with recent versions of the NVDIMM_FAMILY_INTEL spec, and
instead rely on the generic ND_CMD_CALL approach used by the two other IOCTL
families, NVDIMM_FAMILY_{HPE,MSFT}.
* Enhance nfit_test so we can test some of the new things added in version 1.6
of the DSM specification. This includes testing firmware download and
simulating the Last Shutdown State (LSS) status.
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Merge tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm updates from Ross Zwisler:
- Require struct page by default for filesystem DAX to remove a number
of surprising failure cases. This includes failures with direct I/O,
gdb and fork(2).
- Add support for the new Platform Capabilities Structure added to the
NFIT in ACPI 6.2a. This new table tells us whether the platform
supports flushing of CPU and memory controller caches on unexpected
power loss events.
- Revamp vmem_altmap and dev_pagemap handling to clean up code and
better support future future PCI P2P uses.
- Deprecate the ND_IOCTL_SMART_THRESHOLD command whose payload has
become out-of-sync with recent versions of the NVDIMM_FAMILY_INTEL
spec, and instead rely on the generic ND_CMD_CALL approach used by
the two other IOCTL families, NVDIMM_FAMILY_{HPE,MSFT}.
- Enhance nfit_test so we can test some of the new things added in
version 1.6 of the DSM specification. This includes testing firmware
download and simulating the Last Shutdown State (LSS) status.
* tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (37 commits)
libnvdimm, namespace: remove redundant initialization of 'nd_mapping'
acpi, nfit: fix register dimm error handling
libnvdimm, namespace: make min namespace size 4K
tools/testing/nvdimm: force nfit_test to depend on instrumented modules
libnvdimm/nfit_test: adding support for unit testing enable LSS status
libnvdimm/nfit_test: add firmware download emulation
nfit-test: Add platform cap support from ACPI 6.2a to test
libnvdimm: expose platform persistence attribute for nd_region
acpi: nfit: add persistent memory control flag for nd_region
acpi: nfit: Add support for detect platform CPU cache flush on power loss
device-dax: Fix trailing semicolon
libnvdimm, btt: fix uninitialized err_lock
dax: require 'struct page' by default for filesystem dax
ext2: auto disable dax instead of failing mount
ext4: auto disable dax instead of failing mount
mm, dax: introduce pfn_t_special()
mm: Fix devm_memremap_pages() collision handling
mm: Fix memory size alignment in devm_memremap_pages_release()
memremap: merge find_dev_pagemap into get_dev_pagemap
memremap: change devm_memremap_pages interface to use struct dev_pagemap
...
Bharata has noticed that onlining a newly added memory doesn't increase
the total memory, pointing to commit f7f99100d8 ("mm: stop zeroing
memory during allocation in vmemmap") as a culprit. This commit has
changed the way how the memory for memmaps is initialized and moves it
from the allocation time to the initialization time. This works
properly for the early memmap init path.
It doesn't work for the memory hotplug though because we need to mark
page as reserved when the sparsemem section is created and later
initialize it completely during onlining. memmap_init_zone is called in
the early stage of onlining. With the current code it calls
__init_single_page and as such it clears up the whole stage and
therefore online_pages_range skips those pages.
Fix this by skipping mm_zero_struct_page in __init_single_page for
memory hotplug path. This is quite uggly but unifying both early init
and memory hotplug init paths is a large project. Make sure we plug the
regression at least.
Link: http://lkml.kernel.org/r/20180130101141.GW21609@dhcp22.suse.cz
Fixes: f7f99100d8 ("mm: stop zeroing memory during allocation in vmemmap")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Bob Picco <bob.picco@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>
__get_free_pages() will return a virtual address, but it is not just a
32-bit address, for example on a 64-bit system. And this comment really
confuses new readers of mm.
Link: http://lkml.kernel.org/r/1511780964-64864-1-git-send-email-chenjiankang1@huawei.com
Signed-off-by: Jiankang Chen <chenjiankang1@huawei.com>
Reported-by: Hanjun Guo <guohanjun@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In deferred_init_range() we initialize struct pages, and also free them
to buddy allocator. We do it in separate loops, because buddy page is
computed ahead, so we do not want to access a struct page that has not
been initialized yet.
There is still, however, a corner case where it is potentially possible
to access uninitialized struct page: this is when buddy page is from the
next memblock range.
This patch fixes this problem by splitting deferred_init_range() into
two functions: one to initialize struct pages, and another to free them.
In addition, this patch brings the following improvements:
- Get rid of __def_free() helper function. And simplifies loop logic by
adding a new pfn validity check function: deferred_pfn_valid().
- Reduces number of variables that we track. So, there is a higher
chance that we will avoid using stack to store/load variables inside
hot loops.
- Enables future multi-threading of these functions: do initialization
in multiple threads, wait for all threads to finish, do freeing part
in multithreading.
Tested on x86 with 1T of memory to make sure no regressions are
introduced.
[akpm@linux-foundation.org: fix spello in comment]
Link: http://lkml.kernel.org/r/20171107150446.32055-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@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>
Pass the vmem_altmap two levels down instead of needing a lookup.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
With latest kernel I get below bug while testing kdump:
BUG: unable to handle kernel paging request at ffffea00034b1040
IP: zero_resv_unavail+0xbd/0x126
PGD 37b98067 P4D 37b98067 PUD 37b97067 PMD 0
Oops: 0002 [#1] SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 4.15.0-rc1+ #316
Hardware name: LENOVO 20ARS1BJ02/20ARS1BJ02, BIOS GJET92WW (2.42 ) 03/03/2017
task: ffffffff81a0e4c0 task.stack: ffffffff81a00000
RIP: 0010:zero_resv_unavail+0xbd/0x126
RSP: 0000:ffffffff81a03d88 EFLAGS: 00010006
RAX: 0000000000000000 RBX: ffffea00034b1040 RCX: 0000000000000010
RDX: 0000000000000000 RSI: 0000000000000092 RDI: ffffea00034b1040
RBP: 00000000000d2c41 R08: 00000000000000c0 R09: 0000000000000a0d
R10: 0000000000000002 R11: 0000000000007f01 R12: ffffffff81a03d90
R13: ffffea0000000000 R14: 0000000000000063 R15: 0000000000000062
FS: 0000000000000000(0000) GS:ffffffff81c73000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffea00034b1040 CR3: 0000000037609000 CR4: 00000000000606b0
Call Trace:
? free_area_init_nodes+0x640/0x664
? zone_sizes_init+0x58/0x72
? setup_arch+0xb50/0xc6c
? start_kernel+0x64/0x43d
? secondary_startup_64+0xa5/0xb0
Code: c1 e8 0c 48 39 d8 76 27 48 89 de 48 c1 e3 06 48 c7 c7 7a 87 79 81 e8 b0 c0 3e ff 4c 01 eb b9 10 00 00 00 31 c0 48 89 df 49 ff c6 <f3> ab eb bc 6a 00 49 c7 c0 f0 93 d1 81 31 d2 83 ce ff 41 54 49
RIP: zero_resv_unavail+0xbd/0x126 RSP: ffffffff81a03d88
CR2: ffffea00034b1040
---[ end trace f5ba9e8f73c7ee26 ]---
This is introduced by commit a4a3ede213 ("mm: zero reserved and
unavailable struct pages").
The reason is some efi reserved boot ranges is not reported in E820 ram.
In my case it is a bgrt buffer:
efi: mem00: [Boot Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x00000000d2c41000-0x00000000d2c85fff] (0MB)
Use "add_efi_memmap" can workaround the problem with another fix:
http://lkml.kernel.org/r/20171130052327.GA3500@dhcp-128-65.nay.redhat.com
In zero_resv_unavail it would be better to check pfn_valid first before
zero the page struct. This fixes the problem and potential other
similar problems. Also as Pavel Tatashin suggested checks pfn_valid at
the beginning of the section.
The range is backed by real memory. The memory range is efi "Boot
Service Data", that means after ExitBootServices() these ranges can be
used as system ram. But some of them need to be reserved, for example
the bgrt image address in an acpi table, if the image memory is freed
then kexec reboot will fail because kexec inherit same acpi table to
initialize the driver.
Link: http://lkml.kernel.org/r/20171201095048.GA3084@dhcp-128-65.nay.redhat.com
Fixes: a4a3ede213 ("mm: zero reserved and unavailable struct pages")
Signed-off-by: Dave Young <dyoung@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 9cca35d42e ("mm, page_alloc: enable/disable IRQs once
when freeing a list of pages") we see excessive IRQ disabled times of up
to 25ms on an embedded ARM system (tracing overhead included).
This is due to graphics buffers being freed back to the system via
release_pages(). Graphics buffers can be huge, so it's not hard to hit
cases where the list of pages to free has 2048 entries. Disabling IRQs
while freeing all those pages is clearly not a good idea.
Introduce a batch limit, which allows IRQ servicing once every few
pages. The batch count is the same as used in other parts of the MM
subsystem when dealing with IRQ disabled regions.
Link: http://lkml.kernel.org/r/20171207170314.4419-1-l.stach@pengutronix.de
Fixes: 9cca35d42e ("mm, page_alloc: enable/disable IRQs once when freeing a list of pages")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
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>
If the call __alloc_contig_migrate_range() in alloc_contig_range returns
-EBUSY, processing continues so that test_pages_isolated() is called
where there is a tracepoint to identify the busy pages. However, it is
possible for busy pages to become available between the calls to these
two routines. In this case, the range of pages may be allocated.
Unfortunately, the original return code (ret == -EBUSY) is still set and
returned to the caller. Therefore, the caller believes the pages were
not allocated and they are leaked.
Update the comment to indicate that allocation is still possible even if
__alloc_contig_migrate_range returns -EBUSY. Also, clear return code in
this case so that it is not accidentally used or returned to caller.
Link: http://lkml.kernel.org/r/20171122185214.25285-1-mike.kravetz@oracle.com
Fixes: 8ef5849fa8 ("mm/cma: always check which page caused allocation failure")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drain_all_pages backs off when called from a kworker context since
commit 0ccce3b924 ("mm, page_alloc: drain per-cpu pages from workqueue
context") because the original IPI based pcp draining has been replaced
by a WQ based one and the check wanted to prevent from recursion and
inter workers dependencies. This has made some sense at the time
because the system WQ has been used and one worker holding the lock
could be blocked while waiting for new workers to emerge which can be a
problem under OOM conditions.
Since then commit ce612879dd ("mm: move pcp and lru-pcp draining into
single wq") has moved draining to a dedicated (mm_percpu_wq) WQ with a
rescuer so we shouldn't depend on any other WQ activity to make a
forward progress so calling drain_all_pages from a worker context is
safe as long as this doesn't happen from mm_percpu_wq itself which is
not the case because all workers are required to _not_ depend on any MM
locks.
Why is this a problem in the first place? ACPI driven memory hot-remove
(acpi_device_hotplug) is executed from the worker context. We end up
calling __offline_pages to free all the pages and that requires both
lru_add_drain_all_cpuslocked and drain_all_pages to do their job
otherwise we can have dangling pages on pcp lists and fail the offline
operation (__test_page_isolated_in_pageblock would see a page with 0 ref
count but without PageBuddy set).
Fix the issue by removing the worker check in drain_all_pages.
lru_add_drain_all_cpuslocked doesn't have this restriction so it works
as expected.
Link: http://lkml.kernel.org/r/20170828093341.26341-1-mhocko@kernel.org
Fixes: 0ccce3b924 ("mm, page_alloc: drain per-cpu pages from workqueue context")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org> [4.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pageblock skip hints were added as a heuristic for compaction, which
shares core code with CMA. Since CMA reliability would suffer from the
heuristics, compact_control flag ignore_skip_hint was added for the CMA
use case. Since 6815bf3f23 ("mm/compaction: respect ignore_skip_hint
in update_pageblock_skip") the flag also means that CMA won't *update*
the skip hints in addition to ignoring them.
Today, direct compaction can also ignore the skip hints in the last
resort attempt, but there's no reason not to set them when isolation
fails in such case. Thus, this patch splits off a new no_set_skip_hint
flag to avoid the updating, which only CMA sets. This should improve
the heuristics a bit, and allow us to simplify the persistent skip bit
handling as the next step.
Link: http://lkml.kernel.org/r/20171102121706.21504-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
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>
free_area_init_node() calls alloc_node_mem_map(), but this function does
nothing unless we have CONFIG_FLAT_NODE_MEM_MAP.
As a cleanup, we can move the "#ifdef CONFIG_FLAT_NODE_MEM_MAP" within
alloc_node_mem_map() out of the function, and define a
alloc_node_mem_map() { } when CONFIG_FLAT_NODE_MEM_MAP is not present.
This also moves the printk that lays within the "#ifdef
CONFIG_FLAT_NODE_MEM_MAP" block from free_area_init_node() to
alloc_node_mem_map(), getting rid of the "#ifdef
CONFIG_FLAT_NODE_MEM_MAP" in free_area_init_node().
[akpm@linux-foundation.org: clean up the printk while we're there]
Link: http://lkml.kernel.org/r/20171114111935.GA11758@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@techadventures.net>
Acked-by: Michal Hocko <mhocko@suse.com>
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>
alloc_warn() and dump_header() have to explicitly handle NULL nodemask
which forces both paths to use pr_cont. We can do better. printk
already handles NULL pointers properly so all we need is to teach
nodemask_pr_args to handle NULL nodemask carefully. This allows
simplification of both alloc_warn() and dump_header() and gets rid of
pr_cont altogether.
This patch has been motivated by patch from Joe Perches
http://lkml.kernel.org/r/b31236dfe3fc924054fd7842bde678e71d193638.1509991345.git.joe@perches.com
[akpm@linux-foundation.org: fix tile warning, per Arnd]
Link: http://lkml.kernel.org/r/20171109100531.3cn2hcqnuj7mjaju@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Joe Perches <joe@perches.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>
In reset_deferred_meminit() we determine number of pages that must not
be deferred. We initialize pages for at least 2G of memory, but also
pages for reserved memory in this node.
The reserved memory is determined in this function:
memblock_reserved_memory_within(), which operates over physical
addresses, and returns size in bytes. However, reset_deferred_meminit()
assumes that that this function operates with pfns, and returns page
count.
The result is that in the best case machine boots slower than expected
due to initializing more pages than needed in single thread, and in the
worst case panics because fewer than needed pages are initialized early.
Link: http://lkml.kernel.org/r/20171021011707.15191-1-pasha.tatashin@oracle.com
Fixes: 864b9a393d ("mm: consider memblock reservations for deferred memory initialization sizing")
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 63f53dea0c ("mm: warn about allocations which stall for too
long") was a great step for reducing possibility of silent hang up
problem caused by memory allocation stalls. But this commit reverts it,
for it is possible to trigger OOM lockup and/or soft lockups when many
threads concurrently called warn_alloc() (in order to warn about memory
allocation stalls) due to current implementation of printk(), and it is
difficult to obtain useful information due to limitation of synchronous
warning approach.
Current printk() implementation flushes all pending logs using the
context of a thread which called console_unlock(). printk() should be
able to flush all pending logs eventually unless somebody continues
appending to printk() buffer.
Since warn_alloc() started appending to printk() buffer while waiting
for oom_kill_process() to make forward progress when oom_kill_process()
is processing pending logs, it became possible for warn_alloc() to force
oom_kill_process() loop inside printk(). As a result, warn_alloc()
significantly increased possibility of preventing oom_kill_process()
from making forward progress.
---------- Pseudo code start ----------
Before warn_alloc() was introduced:
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
}
goto retry;
After warn_alloc() was introduced:
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
} else if (waited_for_10seconds()) {
atomic_inc(&printk_pending_logs);
}
goto retry;
---------- Pseudo code end ----------
Although waited_for_10seconds() becomes true once per 10 seconds,
unbounded number of threads can call waited_for_10seconds() at the same
time. Also, since threads doing waited_for_10seconds() keep doing
almost busy loop, the thread doing print_one_log() can use little CPU
resource. Therefore, this situation can be simplified like
---------- Pseudo code start ----------
retry:
if (mutex_trylock(&oom_lock)) {
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_lock)
} else {
atomic_inc(&printk_pending_logs);
}
goto retry;
---------- Pseudo code end ----------
when printk() is called faster than print_one_log() can process a log.
One of possible mitigation would be to introduce a new lock in order to
make sure that no other series of printk() (either oom_kill_process() or
warn_alloc()) can append to printk() buffer when one series of printk()
(either oom_kill_process() or warn_alloc()) is already in progress.
Such serialization will also help obtaining kernel messages in readable
form.
---------- Pseudo code start ----------
retry:
if (mutex_trylock(&oom_lock)) {
mutex_lock(&oom_printk_lock);
while (atomic_read(&printk_pending_logs) > 0) {
atomic_dec(&printk_pending_logs);
print_one_log();
}
// Send SIGKILL here.
mutex_unlock(&oom_printk_lock);
mutex_unlock(&oom_lock)
} else {
if (mutex_trylock(&oom_printk_lock)) {
atomic_inc(&printk_pending_logs);
mutex_unlock(&oom_printk_lock);
}
}
goto retry;
---------- Pseudo code end ----------
But this commit does not go that direction, for we don't want to
introduce a new lock dependency, and we unlikely be able to obtain
useful information even if we serialized oom_kill_process() and
warn_alloc().
Synchronous approach is prone to unexpected results (e.g. too late [1],
too frequent [2], overlooked [3]). As far as I know, warn_alloc() never
helped with providing information other than "something is going wrong".
I want to consider asynchronous approach which can obtain information
during stalls with possibly relevant threads (e.g. the owner of
oom_lock and kswapd-like threads) and serve as a trigger for actions
(e.g. turn on/off tracepoints, ask libvirt daemon to take a memory dump
of stalling KVM guest for diagnostic purpose).
This commit temporarily loses ability to report e.g. OOM lockup due to
unable to invoke the OOM killer due to !__GFP_FS allocation request.
But asynchronous approach will be able to detect such situation and emit
warning. Thus, let's remove warn_alloc().
[1] https://bugzilla.kernel.org/show_bug.cgi?id=192981
[2] http://lkml.kernel.org/r/CAM_iQpWuPVGc2ky8M-9yukECtS+zKjiDasNymX7rMcBjBFyM_A@mail.gmail.com
[3] commit db73ee0d46 ("mm, vmscan: do not loop on too_many_isolated for ever"))
Link: http://lkml.kernel.org/r/1509017339-4802-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Reported-by: yuwang.yuwang <yuwang.yuwang@alibaba-inc.com>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.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>
Since commit 97a16fc82a ("mm, page_alloc: only enforce watermarks for
order-0 allocations"), __zone_watermark_ok() check for high-order
allocations will shortcut per-migratetype free list checks for
ALLOC_HARDER allocations, and return true as long as there's free page
of any migratetype. The intention is that ALLOC_HARDER can allocate
from MIGRATE_HIGHATOMIC free lists, while normal allocations can't.
However, as a side effect, the watermark check will then also return
true when there are pages only on the MIGRATE_ISOLATE list, or (prior to
CMA conversion to ZONE_MOVABLE) on the MIGRATE_CMA list. Since the
allocation cannot actually obtain isolated pages, and might not be able
to obtain CMA pages, this can result in a false positive.
The condition should be rare and perhaps the outcome is not a fatal one.
Still, it's better if the watermark check is correct. There also
shouldn't be a performance tradeoff here.
Link: http://lkml.kernel.org/r/20171102125001.23708-1-vbabka@suse.cz
Fixes: 97a16fc82a ("mm, page_alloc: only enforce watermarks for order-0 allocations")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.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>
This is the second step which introduces a tunable interface that allow
numa stats configurable for optimizing zone_statistics(), as suggested
by Dave Hansen and Ying Huang.
=========================================================================
When page allocation performance becomes a bottleneck and you can
tolerate some possible tool breakage and decreased numa counter
precision, you can do:
echo 0 > /proc/sys/vm/numa_stat
In this case, numa counter update is ignored. We can see about
*4.8%*(185->176) drop of cpu cycles per single page allocation and
reclaim on Jesper's page_bench01 (single thread) and *8.1%*(343->315)
drop of cpu cycles per single page allocation and reclaim on Jesper's
page_bench03 (88 threads) running on a 2-Socket Broadwell-based server
(88 threads, 126G memory).
Benchmark link provided by Jesper D Brouer (increase loop times to
10000000):
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench
=========================================================================
When page allocation performance is not a bottleneck and you want all
tooling to work, you can do:
echo 1 > /proc/sys/vm/numa_stat
This is system default setting.
Many thanks to Michal Hocko, Dave Hansen, Ying Huang and Vlastimil Babka
for comments to help improve the original patch.
[keescook@chromium.org: make sure mutex is a global static]
Link: http://lkml.kernel.org/r/20171107213809.GA4314@beast
Link: http://lkml.kernel.org/r/1508290927-8518-1-git-send-email-kemi.wang@intel.com
Signed-off-by: Kemi Wang <kemi.wang@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Ying Huang <ying.huang@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
rmqueue_bulk() fills an empty pcplist with pages from the free list. It
tries to preserve increasing order by pfn to the caller, because it
leads to better performance with some I/O controllers, as explained in
commit e084b2d95e ("page-allocator: preserve PFN ordering when
__GFP_COLD is set").
To preserve the order, it's sufficient to add pages to the tail of the
list as they are retrieved. The current code instead adds to the head
of the list, but then updates the list head pointer to the last added
page, in each step. This does result in the same order, but is
needlessly confusing and potentially wasteful, with no apparent benefit.
This patch simplifies the code and adjusts comment accordingly.
Link: http://lkml.kernel.org/r/f6505442-98a9-12e4-b2cd-0fa83874c159@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
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 the page free path makes no distinction between cache hot and cold
pages, there is no real useful ordering of pages in the free list that
allocation requests can take advantage of. Juding from the users of
__GFP_COLD, it is likely that a number of them are the result of copying
other sites instead of actually measuring the impact. Remove the
__GFP_COLD parameter which simplifies a number of paths in the page
allocator.
This is potentially controversial but bear in mind that the size of the
per-cpu pagelists versus modern cache sizes means that the whole per-cpu
list can often fit in the L3 cache. Hence, there is only a potential
benefit for microbenchmarks that alloc/free pages in a tight loop. It's
even worse when THP is taken into account which has little or no chance
of getting a cache-hot page as the per-cpu list is bypassed and the
zeroing of multiple pages will thrash the cache anyway.
The truncate microbenchmarks are not shown as this patch affects the
allocation path and not the free path. A page fault microbenchmark was
tested but it showed no sigificant difference which is not surprising
given that the __GFP_COLD branches are a miniscule percentage of the
fault path.
Link: http://lkml.kernel.org/r/20171018075952.10627-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most callers users of free_hot_cold_page claim the pages being released
are cache hot. The exception is the page reclaim paths where it is
likely that enough pages will be freed in the near future that the
per-cpu lists are going to be recycled and the cache hotness information
is lost. As no one really cares about the hotness of pages being
released to the allocator, just ditch the parameter.
The APIs are renamed to indicate that it's no longer about hot/cold
pages. It should also be less confusing as there are subtle differences
between them. __free_pages drops a reference and frees a page when the
refcount reaches zero. free_hot_cold_page handled pages whose refcount
was already zero which is non-obvious from the name. free_unref_page
should be more obvious.
No performance impact is expected as the overhead is marginal. The
parameter is removed simply because it is a bit stupid to have a useless
parameter copied everywhere.
[mgorman@techsingularity.net: add pages to head, not tail]
Link: http://lkml.kernel.org/r/20171019154321.qtpzaeftoyyw4iey@techsingularity.net
Link: http://lkml.kernel.org/r/20171018075952.10627-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
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 "Follow-up for speed up page cache truncation", v2.
This series is a follow-on for Jan Kara's series "Speed up page cache
truncation" series. We both ended up looking at the same problem but
saw different problems based on the same data. This series builds upon
his work.
A variety of workloads were compared on four separate machines but each
machine showed gains albeit at different levels. Minimally, some of the
differences are due to NUMA where truncating data from a remote node is
slower than a local node. The workloads checked were
o sparse truncate microbenchmark, tiny
o sparse truncate microbenchmark, large
o reaim-io disk workfile
o dbench4 (modified by mmtests to produce more stable results)
o filebench varmail configuration for small memory size
o bonnie, directory operations, working set size 2*RAM
reaim-io, dbench and filebench all showed minor gains. Truncation does
not dominate those workloads but were tested to ensure no other
regressions. They will not be reported further.
The sparse truncate microbench was written by Jan. It creates a number
of files and then times how long it takes to truncate each one. The
"tiny" configuraiton creates a number of files that easily fits in
memory and times how long it takes to truncate files with page cache.
The large configuration uses enough files to have data that is twice the
size of memory and so timings there include truncating page cache and
working set shadow entries in the radix tree.
Patches 1-4 are the most relevant parts of this series. Patches 5-8 are
optional as they are deleting code that is essentially useless but has a
negligible performance impact.
The changelogs have more information on performance but just for bonnie
delete options, the main comparison is
bonnie
4.14.0-rc5 4.14.0-rc5 4.14.0-rc5
jan-v2 vanilla mel-v2
Hmean SeqCreate ops 76.20 ( 0.00%) 75.80 ( -0.53%) 76.80 ( 0.79%)
Hmean SeqCreate read 85.00 ( 0.00%) 85.00 ( 0.00%) 85.00 ( 0.00%)
Hmean SeqCreate del 13752.31 ( 0.00%) 12090.23 ( -12.09%) 15304.84 ( 11.29%)
Hmean RandCreate ops 76.00 ( 0.00%) 75.60 ( -0.53%) 77.00 ( 1.32%)
Hmean RandCreate read 96.80 ( 0.00%) 96.80 ( 0.00%) 97.00 ( 0.21%)
Hmean RandCreate del 13233.75 ( 0.00%) 11525.35 ( -12.91%) 14446.61 ( 9.16%)
Jan's series is the baseline and the vanilla kernel is 12% slower where
as this series on top gains another 11%. This is from a different
machine than the data in the changelogs but the detailed data was not
collected as there was no substantial change in v2.
This patch (of 8):
Freeing a list of pages current enables/disables IRQs for each page
freed. This patch splits freeing a list of pages into two operations --
preparing the pages for freeing and the actual freeing. This is a
tradeoff - we're taking two passes of the list to free in exchange for
avoiding multiple enable/disable of IRQs.
sparsetruncate (tiny)
4.14.0-rc4 4.14.0-rc4
janbatch-v1r1 oneirq-v1r1
Min Time 149.00 ( 0.00%) 141.00 ( 5.37%)
1st-qrtle Time 150.00 ( 0.00%) 142.00 ( 5.33%)
2nd-qrtle Time 151.00 ( 0.00%) 142.00 ( 5.96%)
3rd-qrtle Time 151.00 ( 0.00%) 143.00 ( 5.30%)
Max-90% Time 153.00 ( 0.00%) 144.00 ( 5.88%)
Max-95% Time 155.00 ( 0.00%) 147.00 ( 5.16%)
Max-99% Time 201.00 ( 0.00%) 195.00 ( 2.99%)
Max Time 236.00 ( 0.00%) 230.00 ( 2.54%)
Amean Time 152.65 ( 0.00%) 144.37 ( 5.43%)
Stddev Time 9.78 ( 0.00%) 10.44 ( -6.72%)
Coeff Time 6.41 ( 0.00%) 7.23 ( -12.84%)
Best99%Amean Time 152.07 ( 0.00%) 143.72 ( 5.50%)
Best95%Amean Time 150.75 ( 0.00%) 142.37 ( 5.56%)
Best90%Amean Time 150.59 ( 0.00%) 142.19 ( 5.58%)
Best75%Amean Time 150.36 ( 0.00%) 141.92 ( 5.61%)
Best50%Amean Time 150.04 ( 0.00%) 141.69 ( 5.56%)
Best25%Amean Time 149.85 ( 0.00%) 141.38 ( 5.65%)
With a tiny number of files, each file truncated has resident page cache
and it shows that time to truncate is roughtly 5-6% with some minor
jitter.
4.14.0-rc4 4.14.0-rc4
janbatch-v1r1 oneirq-v1r1
Hmean SeqCreate ops 65.27 ( 0.00%) 81.86 ( 25.43%)
Hmean SeqCreate read 39.48 ( 0.00%) 47.44 ( 20.16%)
Hmean SeqCreate del 24963.95 ( 0.00%) 26319.99 ( 5.43%)
Hmean RandCreate ops 65.47 ( 0.00%) 82.01 ( 25.26%)
Hmean RandCreate read 42.04 ( 0.00%) 51.75 ( 23.09%)
Hmean RandCreate del 23377.66 ( 0.00%) 23764.79 ( 1.66%)
As expected, there is a small gain for the delete operation.
[mgorman@techsingularity.net: use page_private and set_page_private helpers]
Link: http://lkml.kernel.org/r/20171018101547.mjycw7zreb66jzpa@techsingularity.net
Link: http://lkml.kernel.org/r/20171018075952.10627-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Kara <jack@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__rmqueue(), __rmqueue_fallback(), __rmqueue_smallest() and
__rmqueue_cma_fallback() are all in page allocator's hot path and better
be finished as soon as possible. One way to make them faster is by making
them inline. But as Andrew Morton and Andi Kleen pointed out:
https://lkml.org/lkml/2017/10/10/1252https://lkml.org/lkml/2017/10/10/1279
To make sure they are inlined, we should use __always_inline for them.
With the will-it-scale/page_fault1/process benchmark, when using nr_cpu
processes to stress buddy, the results for will-it-scale.processes with
and without the patch are:
On a 2-sockets Intel-Skylake machine:
compiler base head
gcc-4.4.7 6496131 6911823 +6.4%
gcc-4.9.4 7225110 7731072 +7.0%
gcc-5.4.1 7054224 7688146 +9.0%
gcc-6.2.0 7059794 7651675 +8.4%
On a 4-sockets Intel-Skylake machine:
compiler base head
gcc-4.4.7 13162890 13508193 +2.6%
gcc-4.9.4 14997463 15484353 +3.2%
gcc-5.4.1 14708711 15449805 +5.0%
gcc-6.2.0 14574099 15349204 +5.3%
The above 4 compilers are used because I've done the tests through
Intel's Linux Kernel Performance(LKP) infrastructure and they are the
available compilers there.
The benefit being less on 4 sockets machine is due to the lock
contention there(perf-profile/native_queued_spin_lock_slowpath=81%) is
less severe than on the 2 sockets machine(85%).
What the benchmark does is: it forks nr_cpu processes and then each
process does the following:
1 mmap() 128M anonymous space;
2 writes to each page there to trigger actual page allocation;
3 munmap() it.
in a loop.
https://github.com/antonblanchard/will-it-scale/blob/master/tests/page_fault1.c
Binary size wise, I have locally built them with different compilers:
[aaron@aaronlu obj]$ size */*/mm/page_alloc.o
text data bss dec hex filename
37409 9904 8524 55837 da1d gcc-4.9.4/base/mm/page_alloc.o
38273 9904 8524 56701 dd7d gcc-4.9.4/head/mm/page_alloc.o
37465 9840 8428 55733 d9b5 gcc-5.5.0/base/mm/page_alloc.o
38169 9840 8428 56437 dc75 gcc-5.5.0/head/mm/page_alloc.o
37573 9840 8428 55841 da21 gcc-6.4.0/base/mm/page_alloc.o
38261 9840 8428 56529 dcd1 gcc-6.4.0/head/mm/page_alloc.o
36863 9840 8428 55131 d75b gcc-7.2.0/base/mm/page_alloc.o
37711 9840 8428 55979 daab gcc-7.2.0/head/mm/page_alloc.o
Text size increased about 800 bytes for mm/page_alloc.o.
[aaron@aaronlu obj]$ size */*/vmlinux
text data bss dec hex filename
10342757 5903208 17723392 33969357 20654cd gcc-4.9.4/base/vmlinux
10342757 5903208 17723392 33969357 20654cd gcc-4.9.4/head/vmlinux
10332448 5836608 17715200 33884256 2050860 gcc-5.5.0/base/vmlinux
10332448 5836608 17715200 33884256 2050860 gcc-5.5.0/head/vmlinux
10094546 5836696 17715200 33646442 201676a gcc-6.4.0/base/vmlinux
10094546 5836696 17715200 33646442 201676a gcc-6.4.0/head/vmlinux
10018775 5828732 17715200 33562707 2002053 gcc-7.2.0/base/vmlinux
10018775 5828732 17715200 33562707 2002053 gcc-7.2.0/head/vmlinux
Text size for vmlinux has no change though, probably due to function
alignment.
Link: http://lkml.kernel.org/r/20171013063111.GA26032@intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmemmap_alloc_block() will no longer zero the block, so zero memory at
its call sites for everything except struct pages. Struct page memory
is zero'd by struct page initialization.
Replace allocators in sparse-vmemmap to use the non-zeroing version.
So, we will get the performance improvement by zeroing the memory in
parallel when struct pages are zeroed.
Add struct page zeroing as a part of initialization of other fields in
__init_single_page().
This single thread performance collected on: Intel(R) Xeon(R) CPU E7-8895
v3 @ 2.60GHz with 1T of memory (268400646 pages in 8 nodes):
BASE FIX
sparse_init 11.244671836s 0.007199623s
zone_sizes_init 4.879775891s 8.355182299s
--------------------------
Total 16.124447727s 8.362381922s
sparse_init is where memory for struct pages is zeroed, and the zeroing
part is moved later in this patch into __init_single_page(), which is
called from zone_sizes_init().
[akpm@linux-foundation.org: make vmemmap_alloc_block_zero() private to sparse-vmemmap.c]
Link: http://lkml.kernel.org/r/20171013173214.27300-10-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Tested-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some memory is reserved but unavailable: not present in memblock.memory
(because not backed by physical pages), but present in memblock.reserved.
Such memory has backing struct pages, but they are not initialized by
going through __init_single_page().
In some cases these struct pages are accessed even if they do not
contain any data. One example is page_to_pfn() might access page->flags
if this is where section information is stored (CONFIG_SPARSEMEM,
SECTION_IN_PAGE_FLAGS).
One example of such memory: trim_low_memory_range() unconditionally
reserves from pfn 0, but e820__memblock_setup() might provide the
exiting memory from pfn 1 (i.e. KVM).
Since struct pages are zeroed in __init_single_page(), and not during
allocation time, we must zero such struct pages explicitly.
The patch involves adding a new memblock iterator:
for_each_resv_unavail_range(i, p_start, p_end)
Which iterates through reserved && !memory lists, and we zero struct pages
explicitly by calling mm_zero_struct_page().
===
Here is more detailed example of problem that this patch is addressing:
Run tested on qemu with the following arguments:
-enable-kvm -cpu kvm64 -m 512 -smp 2
This patch reports that there are 98 unavailable pages.
They are: pfn 0 and pfns in range [159, 255].
Note, trim_low_memory_range() reserves only pfns in range [0, 15], it does
not reserve [159, 255] ones.
e820__memblock_setup() reports linux that the following physical ranges are
available:
[1 , 158]
[256, 130783]
Notice, that exactly unavailable pfns are missing!
Now, lets check what we have in zone 0: [1, 131039]
pfn 0, is not part of the zone, but pfns [1, 158], are.
However, the bigger problem we have if we do not initialize these struct
pages is with memory hotplug. Because, that path operates at 2M
boundaries (section_nr). And checks if 2M range of pages is hot
removable. It starts with first pfn from zone, rounds it down to 2M
boundary (sturct pages are allocated at 2M boundaries when vmemmap is
created), and checks if that section is hot removable. In this case
start with pfn 1 and convert it down to pfn 0. Later pfn is converted
to struct page, and some fields are checked. Now, if we do not zero
struct pages, we get unpredictable results.
In fact when CONFIG_VM_DEBUG is enabled, and we explicitly set all
vmemmap memory to ones, the following panic is observed with kernel test
without this patch applied:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: is_pageblock_removable_nolock+0x35/0x90
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT
...
task: ffff88001f4e2900 task.stack: ffffc90000314000
RIP: 0010:is_pageblock_removable_nolock+0x35/0x90
Call Trace:
? is_mem_section_removable+0x5a/0xd0
show_mem_removable+0x6b/0xa0
dev_attr_show+0x1b/0x50
sysfs_kf_seq_show+0xa1/0x100
kernfs_seq_show+0x22/0x30
seq_read+0x1ac/0x3a0
kernfs_fop_read+0x36/0x190
? security_file_permission+0x90/0xb0
__vfs_read+0x16/0x30
vfs_read+0x81/0x130
SyS_read+0x44/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xbd
Link: http://lkml.kernel.org/r/20171013173214.27300-7-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Tested-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* A new variant of memblock_virt_alloc_* allocations:
memblock_virt_alloc_try_nid_raw()
- Does not zero the allocated memory
- Does not panic if request cannot be satisfied
* optimize early system hash allocations
Clients can call alloc_large_system_hash() with flag: HASH_ZERO to
specify that memory that was allocated for system hash needs to be
zeroed, otherwise the memory does not need to be zeroed, and client will
initialize it.
If memory does not need to be zero'd, call the new
memblock_virt_alloc_raw() interface, and thus improve the boot
performance.
* debug for raw alloctor
When CONFIG_DEBUG_VM is enabled, this patch sets all the memory that is
returned by memblock_virt_alloc_try_nid_raw() to ones to ensure that no
places excpect zeroed memory.
Link: http://lkml.kernel.org/r/20171013173214.27300-6-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Tested-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "complete deferred page initialization", v12.
SMP machines can benefit from the DEFERRED_STRUCT_PAGE_INIT config
option, which defers initializing struct pages until all cpus have been
started so it can be done in parallel.
However, this feature is sub-optimal, because the deferred page
initialization code expects that the struct pages have already been
zeroed, and the zeroing is done early in boot with a single thread only.
Also, we access that memory and set flags before struct pages are
initialized. All of this is fixed in this patchset.
In this work we do the following:
- Never read access struct page until it was initialized
- Never set any fields in struct pages before they are initialized
- Zero struct page at the beginning of struct page initialization
==========================================================================
Performance improvements on x86 machine with 8 nodes:
Intel(R) Xeon(R) CPU E7-8895 v3 @ 2.60GHz and 1T of memory:
TIME SPEED UP
base no deferred: 95.796233s
fix no deferred: 79.978956s 19.77%
base deferred: 77.254713s
fix deferred: 55.050509s 40.34%
==========================================================================
SPARC M6 3600 MHz with 15T of memory
TIME SPEED UP
base no deferred: 358.335727s
fix no deferred: 302.320936s 18.52%
base deferred: 237.534603s
fix deferred: 182.103003s 30.44%
==========================================================================
Raw dmesg output with timestamps:
x86 base no deferred: https://hastebin.com/ofunepurit.scala
x86 base deferred: https://hastebin.com/ifazegeyas.scala
x86 fix no deferred: https://hastebin.com/pegocohevo.scala
x86 fix deferred: https://hastebin.com/ofupevikuk.scala
sparc base no deferred: https://hastebin.com/ibobeteken.go
sparc base deferred: https://hastebin.com/fariqimiyu.go
sparc fix no deferred: https://hastebin.com/muhegoheyi.go
sparc fix deferred: https://hastebin.com/xadinobutu.go
This patch (of 11):
deferred_init_memmap() is called when struct pages are initialized later
in boot by slave CPUs. This patch simplifies and optimizes this
function, and also fixes a couple issues (described below).
The main change is that now we are iterating through free memblock areas
instead of all configured memory. Thus, we do not have to check if the
struct page has already been initialized.
=====
In deferred_init_memmap() where all deferred struct pages are
initialized we have a check like this:
if (page->flags) {
VM_BUG_ON(page_zone(page) != zone);
goto free_range;
}
This way we are checking if the current deferred page has already been
initialized. It works, because memory for struct pages has been zeroed,
and the only way flags are not zero if it went through
__init_single_page() before. But, once we change the current behavior
and won't zero the memory in memblock allocator, we cannot trust
anything inside "struct page"es until they are initialized. This patch
fixes this.
The deferred_init_memmap() is re-written to loop through only free
memory ranges provided by memblock.
Note, this first issue is relevant only when the following change is
merged:
=====
This patch fixes another existing issue on systems that have holes in
zones i.e CONFIG_HOLES_IN_ZONE is defined.
In for_each_mem_pfn_range() we have code like this:
if (!pfn_valid_within(pfn)
goto free_range;
Note: 'page' is not set to NULL and is not incremented but 'pfn'
advances. Thus means if deferred struct pages are enabled on systems
with these kind of holes, linux would get memory corruptions. I have
fixed this issue by defining a new macro that performs all the necessary
operations when we free the current set of pages.
[pasha.tatashin@oracle.com: buddy page accessed before initialized]
Link: http://lkml.kernel.org/r/20171102170221.7401-2-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20171013173214.27300-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Tested-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
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 "kmemcheck: kill kmemcheck", v2.
As discussed at LSF/MM, kill kmemcheck.
KASan is a replacement that is able to work without the limitation of
kmemcheck (single CPU, slow). KASan is already upstream.
We are also not aware of any users of kmemcheck (or users who don't
consider KASan as a suitable replacement).
The only objection was that since KASAN wasn't supported by all GCC
versions provided by distros at that time we should hold off for 2
years, and try again.
Now that 2 years have passed, and all distros provide gcc that supports
KASAN, kill kmemcheck again for the very same reasons.
This patch (of 4):
Remove kmemcheck annotations, and calls to kmemcheck from the kernel.
[alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs]
Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com
Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Hansen <devtimhansen@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reserved pages should be completely ignored by the core mm because they
have a special meaning for their owners. has_unmovable_pages doesn't
check those so we rely on other tests (reference count, or PageLRU) to
fail on such pages. Althought this happens to work it is safer to
simply check for those explicitly and do not rely on the owner of the
page to abuse those fields for special purposes.
Please note that this is more of a further fortification of the code
rahter than a fix of an existing issue.
Link: http://lkml.kernel.org/r/20171013120756.jeopthigbmm3c7bl@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Joonsoo has noticed that "mm: drop migrate type checks from
has_unmovable_pages" would break CMA allocator because it relies on
has_unmovable_pages returning false even for CMA pageblocks which in
fact don't have to be movable:
alloc_contig_range
start_isolate_page_range
set_migratetype_isolate
has_unmovable_pages
This is a result of the code sharing between CMA and memory hotplug
while each one has a different idea of what has_unmovable_pages should
return. This is unfortunate but fixing it properly would require a lot
of code duplication.
Fix the issue by introducing the requested migrate type argument and
special case MIGRATE_CMA case where CMA page blocks are handled
properly. This will work for memory hotplug because it requires
MIGRATE_MOVABLE.
Link: http://lkml.kernel.org/r/20171019122118.y6cndierwl2vnguj@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Ran Wang <ran.wang_1@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michael has noticed that the memory offline tries to migrate kernel code
pages when doing
echo 0 > /sys/devices/system/memory/memory0/online
The current implementation will fail the operation after several failed
page migration attempts but we shouldn't even attempt to migrate that
memory and fail right away because this memory is clearly not
migrateable. This will become a real problem when we drop the retry
loop counter resp. timeout.
The real problem is in has_unmovable_pages in fact. We should fail if
there are any non migrateable pages in the area. In orther to guarantee
that remove the migrate type checks because MIGRATE_MOVABLE is not
guaranteed to contain only migrateable pages. It is merely a heuristic.
Similarly MIGRATE_CMA does guarantee that the page allocator doesn't
allocate any non-migrateable pages from the block but CMA allocations
themselves are unlikely to migrateable. Therefore remove both checks.
[akpm@linux-foundation.org: remove unused local `mt']
Link: http://lkml.kernel.org/r/20171013120013.698-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ran Wang <ran.wang_1@nxp.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memmap_init_zone gets a pfn range to initialize and it can be really
large resulting in a soft lockup on non-preemptible kernels
NMI watchdog: BUG: soft lockup - CPU#31 stuck for 23s! [kworker/u642:5:1720]
[...]
task: ffff88ecd7e902c0 ti: ffff88eca4e50000 task.ti: ffff88eca4e50000
RIP: move_pfn_range_to_zone+0x185/0x1d0
[...]
Call Trace:
devm_memremap_pages+0x2c7/0x430
pmem_attach_disk+0x2fd/0x3f0 [nd_pmem]
nvdimm_bus_probe+0x64/0x110 [libnvdimm]
driver_probe_device+0x1f7/0x420
bus_for_each_drv+0x52/0x80
__device_attach+0xb0/0x130
bus_probe_device+0x87/0xa0
device_add+0x3fc/0x5f0
nd_async_device_register+0xe/0x40 [libnvdimm]
async_run_entry_fn+0x43/0x150
process_one_work+0x14e/0x410
worker_thread+0x116/0x490
kthread+0xc7/0xe0
ret_from_fork+0x3f/0x70
Fix this by adding a scheduling point once per page block.
Link: http://lkml.kernel.org/r/20170918121410.24466-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Johannes Thumshirn <jthumshirn@suse.de>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Dan Williams <dan.j.williams@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function is called from __meminit context and calls other __meminit
functions but isn't it self mark as such today:
WARNING: vmlinux.o(.text.unlikely+0x4516): Section mismatch in reference from the function init_reserved_page() to the function .meminit.text:early_pfn_to_nid()
The function init_reserved_page() references the function __meminit early_pfn_to_nid().
This is often because init_reserved_page lacks a __meminit annotation or the annotation of early_pfn_to_nid is wrong.
On most compilers, we don't notice this because the function gets
inlined all the time. Adding __meminit here fixes the harmless warning
for the old versions and is generally the correct annotation.
Link: http://lkml.kernel.org/r/20170915193149.901180-1-arnd@arndb.de
Fixes: 7e18adb4f8 ("mm: meminit: initialise remaining struct pages in parallel with kswapd")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We are by error initializing alloc_flags before gfp_allowed_mask is
applied. This could cause problems after pm_restrict_gfp_mask() is called
during suspend operation. Apply gfp_allowed_mask before initializing
alloc_flags so that the first allocation attempt uses correct flags.
Link: http://lkml.kernel.org/r/201709020016.ADJ21342.OFLJHOOSMFVtFQ@I-love.SAKURA.ne.jp
Fixes: 83d4ca8148 ("mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Separate NUMA statistics from zone statistics", v2.
Each page allocation updates a set of per-zone statistics with a call to
zone_statistics(). As discussed in 2017 MM summit, these are a
substantial source of overhead in the page allocator and are very rarely
consumed. This significant overhead in cache bouncing caused by zone
counters (NUMA associated counters) update in parallel in multi-threaded
page allocation (pointed out by Dave Hansen).
A link to the MM summit slides:
http://people.netfilter.org/hawk/presentations/MM-summit2017/MM-summit2017-JesperBrouer.pdf
To mitigate this overhead, this patchset separates NUMA statistics from
zone statistics framework, and update NUMA counter threshold to a fixed
size of MAX_U16 - 2, as a small threshold greatly increases the update
frequency of the global counter from local per cpu counter (suggested by
Ying Huang). The rationality is that these statistics counters don't
need to be read often, unlike other VM counters, so it's not a problem
to use a large threshold and make readers more expensive.
With this patchset, we see 31.3% drop of CPU cycles(537-->369, see
below) for per single page allocation and reclaim on Jesper's
page_bench03 benchmark. Meanwhile, this patchset keeps the same style
of virtual memory statistics with little end-user-visible effects (only
move the numa stats to show behind zone page stats, see the first patch
for details).
I did an experiment of single page allocation and reclaim concurrently
using Jesper's page_bench03 benchmark on a 2-Socket Broadwell-based
server (88 processors with 126G memory) with different size of threshold
of pcp counter.
Benchmark provided by Jesper D Brouer(increase loop times to 10000000):
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench
Threshold CPU cycles Throughput(88 threads)
32 799 241760478
64 640 301628829
125 537 358906028 <==> system by default
256 468 412397590
512 428 450550704
4096 399 482520943
20000 394 489009617
30000 395 488017817
65533 369(-31.3%) 521661345(+45.3%) <==> with this patchset
N/A 342(-36.3%) 562900157(+56.8%) <==> disable zone_statistics
This patch (of 3):
In this patch, NUMA statistics is separated from zone statistics
framework, all the call sites of NUMA stats are changed to use
numa-stats-specific functions, it does not have any functionality change
except that the number of NUMA stats is shown behind zone page stats
when users *read* the zone info.
E.g. cat /proc/zoneinfo
***Base*** ***With this patch***
nr_free_pages 3976 nr_free_pages 3976
nr_zone_inactive_anon 0 nr_zone_inactive_anon 0
nr_zone_active_anon 0 nr_zone_active_anon 0
nr_zone_inactive_file 0 nr_zone_inactive_file 0
nr_zone_active_file 0 nr_zone_active_file 0
nr_zone_unevictable 0 nr_zone_unevictable 0
nr_zone_write_pending 0 nr_zone_write_pending 0
nr_mlock 0 nr_mlock 0
nr_page_table_pages 0 nr_page_table_pages 0
nr_kernel_stack 0 nr_kernel_stack 0
nr_bounce 0 nr_bounce 0
nr_zspages 0 nr_zspages 0
numa_hit 0 *nr_free_cma 0*
numa_miss 0 numa_hit 0
numa_foreign 0 numa_miss 0
numa_interleave 0 numa_foreign 0
numa_local 0 numa_interleave 0
numa_other 0 numa_local 0
*nr_free_cma 0* numa_other 0
... ...
vm stats threshold: 10 vm stats threshold: 10
... ...
The next patch updates the numa stats counter size and threshold.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1503568801-21305-2-git-send-email-kemi.wang@intel.com
Signed-off-by: Kemi Wang <kemi.wang@intel.com>
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For ages we have been relying on TIF_MEMDIE thread flag to mark OOM
victims and then, among other things, to give these threads full access
to memory reserves. There are few shortcomings of this implementation,
though.
First of all and the most serious one is that the full access to memory
reserves is quite dangerous because we leave no safety room for the
system to operate and potentially do last emergency steps to move on.
Secondly this flag is per task_struct while the OOM killer operates on
mm_struct granularity so all processes sharing the given mm are killed.
Giving the full access to all these task_structs could lead to a quick
memory reserves depletion. We have tried to reduce this risk by giving
TIF_MEMDIE only to the main thread and the currently allocating task but
that doesn't really solve this problem while it surely opens up a room
for corner cases - e.g. GFP_NO{FS,IO} requests might loop inside the
allocator without access to memory reserves because a particular thread
was not the group leader.
Now that we have the oom reaper and that all oom victims are reapable
after 1b51e65eab ("oom, oom_reaper: allow to reap mm shared by the
kthreads") we can be more conservative and grant only partial access to
memory reserves because there are reasonable chances of the parallel
memory freeing. We still want some access to reserves because we do not
want other consumers to eat up the victim's freed memory. oom victims
will still contend with __GFP_HIGH users but those shouldn't be so
aggressive to starve oom victims completely.
Introduce ALLOC_OOM flag and give all tsk_is_oom_victim tasks access to
the half of the reserves. This makes the access to reserves independent
on which task has passed through mark_oom_victim. Also drop any usage
of TIF_MEMDIE from the page allocator proper and replace it by
tsk_is_oom_victim as well which will make page_alloc.c completely
TIF_MEMDIE free finally.
CONFIG_MMU=n doesn't have oom reaper so let's stick to the original
ALLOC_NO_WATERMARKS approach.
There is a demand to make the oom killer memcg aware which will imply
many tasks killed at once. This change will allow such a usecase
without worrying about complete memory reserves depletion.
Link: http://lkml.kernel.org/r/20170810075019.28998-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.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>
global_page_state is error prone as a recent bug report pointed out [1].
It only returns proper values for zone based counters as the enum it
gets suggests. We already have global_node_page_state so let's rename
global_page_state to global_zone_page_state to be more explicit here.
All existing users seems to be correct:
$ git grep "global_page_state(NR_" | sed 's@.*(\(NR_[A-Z_]*\)).*@\1@' | sort | uniq -c
2 NR_BOUNCE
2 NR_FREE_CMA_PAGES
11 NR_FREE_PAGES
1 NR_KERNEL_STACK_KB
1 NR_MLOCK
2 NR_PAGETABLE
This patch shouldn't introduce any functional change.
[1] http://lkml.kernel.org/r/201707260628.v6Q6SmaS030814@www262.sakura.ne.jp
Link: http://lkml.kernel.org/r/20170801134256.5400-2-hannes@cmpxchg.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zonelists_mutex was introduced by commit 4eaf3f6439 ("mem-hotplug: fix
potential race while building zonelist for new populated zone") to
protect zonelist building from races. This is no longer needed though
because both memory online and offline are fully serialized. New users
have grown since then.
Notably setup_per_zone_wmarks wants to prevent from races between memory
hotplug, khugepaged setup and manual min_free_kbytes update via sysctl
(see cfd3da1e49 ("mm: Serialize access to min_free_kbytes"). Let's
add a private lock for that purpose. This will not prevent from seeing
halfway through memory hotplug operation but that shouldn't be a big
deal becuse memory hotplug will update watermarks explicitly so we will
eventually get a full picture. The lock just makes sure we won't race
when updating watermarks leading to weird results.
Also __build_all_zonelists manipulates global data so add a private lock
for it as well. This doesn't seem to be necessary today but it is more
robust to have a lock there.
While we are at it make sure we document that memory online/offline
depends on a full serialization either via mem_hotplug_begin() or
device_lock.
Link: http://lkml.kernel.org/r/20170721143915.14161-9-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Haicheng Li <haicheng.li@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_all_zonelists has been (ab)using stop_machine to make sure that
zonelists do not change while somebody is looking at them. This is is
just a gross hack because a) it complicates the context from which we
can call build_all_zonelists (see 3f906ba236 ("mm/memory-hotplug:
switch locking to a percpu rwsem")) and b) is is not really necessary
especially after "mm, page_alloc: simplify zonelist initialization" and
c) it doesn't really provide the protection it claims (see below).
Updates of the zonelists happen very seldom, basically only when a zone
becomes populated during memory online or when it loses all the memory
during offline. A racing iteration over zonelists could either miss a
zone or try to work on one zone twice. Both of these are something we
can live with occasionally because there will always be at least one
zone visible so we are not likely to fail allocation too easily for
example.
Please note that the original stop_machine approach doesn't really
provide a better exclusion because the iteration might be interrupted
half way (unless the whole iteration is preempt disabled which is not
the case in most cases) so the some zones could still be seen twice or a
zone missed.
I have run the pathological online/offline of the single memblock in the
movable zone while stressing the same small node with some memory
pressure.
Node 1, zone DMA
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 943, 943, 943)
Node 1, zone DMA32
pages free 227310
min 8294
low 10367
high 12440
spanned 262112
present 262112
managed 241436
protection: (0, 0, 0, 0)
Node 1, zone Normal
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 0, 0, 1024)
Node 1, zone Movable
pages free 32722
min 85
low 117
high 149
spanned 32768
present 32768
managed 32768
protection: (0, 0, 0, 0)
root@test1:/sys/devices/system/node/node1# while true
do
echo offline > memory34/state
echo online_movable > memory34/state
done
root@test1:/mnt/data/test/linux-3.7-rc5# numactl --preferred=1 make -j4
and it survived without any unexpected behavior. While this is not
really a great testing coverage it should exercise the allocation path
quite a lot.
Link: http://lkml.kernel.org/r/20170721143915.14161-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_zonelists gradually builds zonelists from the nearest to the most
distant node. As we do not know how many populated zones we will have
in each node we rely on the _zoneref to terminate initialized part of
the zonelist by a NULL zone. While this is functionally correct it is
quite suboptimal because we cannot allow updaters to race with zonelists
users because they could see an empty zonelist and fail the allocation
or hit the OOM killer in the worst case.
We can do much better, though. We can store the node ordering into an
already existing node_order array and then give this array to
build_zonelists_in_node_order and do the whole initialization at once.
zonelists consumers still might see halfway initialized state but that
should be much more tolerateable because the list will not be empty and
they would either see some zone twice or skip over some zone(s) in the
worst case which shouldn't lead to immediate failures.
While at it let's simplify build_zonelists_node which is rather
confusing now. It gets an index into the zoneref array and returns the
updated index for the next iteration. Let's rename the function to
build_zonerefs_node to better reflect its purpose and give it zoneref
array to update. The function doesn't the index anymore. It just
returns the number of added zones so that the caller can advance the
zonered array start for the next update.
This patch alone doesn't introduce any functional change yet, though, it
is merely a preparatory work for later changes.
Link: http://lkml.kernel.org/r/20170721143915.14161-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_all_zonelists gets a zone parameter to initialize zone's pagesets.
There is only a single user which gives a non-NULL zone parameter and
that one doesn't really need the rest of the build_all_zonelists (see
commit 6dcd73d701 ("memory-hotplug: allocate zone's pcp before
onlining pages")).
Therefore remove setup_zone_pageset from build_all_zonelists and call it
from its only user directly. This will also remove a pointless zonlists
rebuilding which is always good.
Link: http://lkml.kernel.org/r/20170721143915.14161-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__build_all_zonelists reinitializes each online cpu local node for
CONFIG_HAVE_MEMORYLESS_NODES. This makes sense because previously
memory less nodes could gain some memory during memory hotplug and so
the local node should be changed for CPUs close to such a node. It
makes less sense to do that unconditionally for a newly creaded NUMA
node which is still offline and without any memory.
Let's also simplify the cpu loop and use for_each_online_cpu instead of
an explicit cpu_online check for all possible cpus.
Link: http://lkml.kernel.org/r/20170721143915.14161-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
boot_pageset is a boot time hack which gets superseded by normal
pagesets later in the boot process. It makes zero sense to reinitialize
it again and again during memory hotplug.
Link: http://lkml.kernel.org/r/20170721143915.14161-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "cleanup zonelists initialization", v1.
This is aimed at cleaning up the zonelists initialization code we have
but the primary motivation was bug report [2] which got resolved but the
usage of stop_machine is just too ugly to live. Most patches are
straightforward but 3 of them need a special consideration.
Patch 1 removes zone ordered zonelists completely. I am CCing linux-api
because this is a user visible change. As I argue in the patch
description I do not think we have a strong usecase for it these days.
I have kept sysctl in place and warn into the log if somebody tries to
configure zone lists ordering. If somebody has a real usecase for it we
can revert this patch but I do not expect anybody will actually notice
runtime differences. This patch is not strictly needed for the rest but
it made patch 6 easier to implement.
Patch 7 removes stop_machine from build_all_zonelists without adding any
special synchronization between iterators and updater which I _believe_
is acceptable as explained in the changelog. I hope I am not missing
anything.
Patch 8 then removes zonelists_mutex which is kind of ugly as well and
not really needed AFAICS but a care should be taken when double checking
my thinking.
This patch (of 9):
Supporting zone ordered zonelists costs us just a lot of code while the
usefulness is arguable if existent at all. Mel has already made node
ordering default on 64b systems. 32b systems are still using
ZONELIST_ORDER_ZONE because it is considered better to fallback to a
different NUMA node rather than consume precious lowmem zones.
This argument is, however, weaken by the fact that the memory reclaim
has been reworked to be node rather than zone oriented. This means that
lowmem requests have to skip over all highmem pages on LRUs already and
so zone ordering doesn't save the reclaim time much. So the only
advantage of the zone ordering is under a light memory pressure when
highmem requests do not ever hit into lowmem zones and the lowmem
pressure doesn't need to reclaim.
Considering that 32b NUMA systems are rather suboptimal already and it
is generally advisable to use 64b kernel on such a HW I believe we
should rather care about the code maintainability and just get rid of
ZONELIST_ORDER_ZONE altogether. Keep systcl in place and warn if
somebody tries to set zone ordering either from kernel command line or
the sysctl.
[mhocko@suse.com: reading vm.numa_zonelist_order will never terminate]
Link: http://lkml.kernel.org/r/20170721143915.14161-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9adb62a5df ("mm/hotplug: correctly setup fallback zonelists
when creating new pgdat") tries to build the correct zonelist for a
newly added node, while it is not necessary to rebuild it for already
exist nodes.
In build_zonelists(), it will iterate on nodes with memory. For a newly
added node, it will have memory until node_states_set_node() is called
in online_pages().
This patch avoids rebuilding the zonelists for already existing nodes.
build_zonelists_node() uses managed_zone(zone) checks, so it should not
include empty zones anyway. So effectively we avoid some pointless work
under stop_machine().
[akpm@linux-foundation.org: tweak comment text]
[akpm@linux-foundation.org: coding-style tweak, per Vlastimil]
Link: http://lkml.kernel.org/r/20170626035822.50155-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We are doing a last second memory allocation attempt before calling
out_of_memory(). But since slab shrinker functions might indirectly
wait for other thread's __GFP_DIRECT_RECLAIM && !__GFP_NORETRY memory
allocations via sleeping locks, calling slab shrinker functions from
node_reclaim() from get_page_from_freelist() with oom_lock held has
possibility of deadlock. Therefore, make sure that last second memory
allocation attempt does not call slab shrinker functions.
Link: http://lkml.kernel.org/r/1503577106-9196-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a problem that when counting the pages for creating the
hibernation snapshot will take significant amount of time, especially on
system with large memory. Since the counting job is performed with irq
disabled, this might lead to NMI lockup. The following warning were
found on a system with 1.5TB DRAM:
Freezing user space processes ... (elapsed 0.002 seconds) done.
OOM killer disabled.
PM: Preallocating image memory...
NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
CPU: 27 PID: 3128 Comm: systemd-sleep Not tainted 4.13.0-0.rc2.git0.1.fc27.x86_64 #1
task: ffff9f01971ac000 task.stack: ffffb1a3f325c000
RIP: 0010:memory_bm_find_bit+0xf4/0x100
Call Trace:
swsusp_set_page_free+0x2b/0x30
mark_free_pages+0x147/0x1c0
count_data_pages+0x41/0xa0
hibernate_preallocate_memory+0x80/0x450
hibernation_snapshot+0x58/0x410
hibernate+0x17c/0x310
state_store+0xdf/0xf0
kobj_attr_store+0xf/0x20
sysfs_kf_write+0x37/0x40
kernfs_fop_write+0x11c/0x1a0
__vfs_write+0x37/0x170
vfs_write+0xb1/0x1a0
SyS_write+0x55/0xc0
entry_SYSCALL_64_fastpath+0x1a/0xa5
...
done (allocated 6590003 pages)
PM: Allocated 26360012 kbytes in 19.89 seconds (1325.28 MB/s)
It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup was
triggered. In case the timeout of the NMI watch dog has been set to 1
second, a safe interval should be 6590003/20 = 320k pages in theory.
However there might also be some platforms running at a lower frequency,
so feed the watchdog every 100k pages.
[yu.c.chen@intel.com: simplification]
Link: http://lkml.kernel.org/r/1503460079-29721-1-git-send-email-yu.c.chen@intel.com
[yu.c.chen@intel.com: use interval of 128k instead of 100k to avoid modulus]
Link: http://lkml.kernel.org/r/1503328098-5120-1-git-send-email-yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Reported-by: Jan Filipcewicz <jan.filipcewicz@intel.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Len Brown <lenb@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is existing use after free bug when deferred struct pages are
enabled:
The memblock_add() allocates memory for the memory array if more than
128 entries are needed. See comment in e820__memblock_setup():
* The bootstrap memblock region count maximum is 128 entries
* (INIT_MEMBLOCK_REGIONS), but EFI might pass us more E820 entries
* than that - so allow memblock resizing.
This memblock memory is freed here:
free_low_memory_core_early()
We access the freed memblock.memory later in boot when deferred pages
are initialized in this path:
deferred_init_memmap()
for_each_mem_pfn_range()
__next_mem_pfn_range()
type = &memblock.memory;
One possible explanation for why this use-after-free hasn't been hit
before is that the limit of INIT_MEMBLOCK_REGIONS has never been
exceeded at least on systems where deferred struct pages were enabled.
Tested by reducing INIT_MEMBLOCK_REGIONS down to 4 from the current 128,
and verifying in qemu that this code is getting excuted and that the
freed pages are sane.
Link: http://lkml.kernel.org/r/1502485554-318703-2-git-send-email-pasha.tatashin@oracle.com
Fixes: 7e18adb4f8 ("mm: meminit: initialise remaining struct pages in parallel with kswapd")
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Conflicts:
include/linux/mm_types.h
mm/huge_memory.c
I removed the smp_mb__before_spinlock() like the following commit does:
8b1b436dd1 ("mm, locking: Rework {set,clear,mm}_tlb_flush_pending()")
and fixed up the affected commits.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The RDMA subsystem can generate several thousand of these messages per
second eventually leading to a kernel crash. Ratelimit these messages
to prevent this crash.
Doug said:
"I've been carrying a version of this for several kernel versions. I
don't remember when they started, but we have one (and only one) class
of machines: Dell PE R730xd, that generate these errors. When it
happens, without a rate limit, we get rcu timeouts and kernel oopses.
With the rate limit, we just get a lot of annoying kernel messages but
the machine continues on, recovers, and eventually the memory
operations all succeed"
And:
"> Well... why are all these EBUSY's occurring? It sounds inefficient
> (at least) but if it is expected, normal and unavoidable then
> perhaps we should just remove that message altogether?
I don't have an answer to that question. To be honest, I haven't
looked real hard. We never had this at all, then it started out of the
blue, but only on our Dell 730xd machines (and it hits all of them),
but no other classes or brands of machines. And we have our 730xd
machines loaded up with different brands and models of cards (for
instance one dedicated to mlx4 hardware, one for qib, one for mlx5, an
ocrdma/cxgb4 combo, etc), so the fact that it hit all of the machines
meant it wasn't tied to any particular brand/model of RDMA hardware.
To me, it always smelled of a hardware oddity specific to maybe the
CPUs or mainboard chipsets in these machines, so given that I'm not an
mm expert anyway, I never chased it down.
A few other relevant details: it showed up somewhere around 4.8/4.9 or
thereabouts. It never happened before, but the prinkt has been there
since the 3.18 days, so possibly the test to trigger this message was
changed, or something else in the allocator changed such that the
situation started happening on these machines?
And, like I said, it is specific to our 730xd machines (but they are
all identical, so that could mean it's something like their specific
ram configuration is causing the allocator to hit this on these
machine but not on other machines in the cluster, I don't want to say
it's necessarily the model of chipset or CPU, there are other bits of
identicalness between these machines)"
Link: http://lkml.kernel.org/r/499c0f6cc10d6eb829a67f2a4d75b4228a9b356e.1501695897.git.jtoppins@redhat.com
Signed-off-by: Jonathan Toppins <jtoppins@redhat.com>
Reviewed-by: Doug Ledford <dledford@redhat.com>
Tested-by: Doug Ledford <dledford@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As Tetsuo points out:
"Commit 385386cff4 ("mm: vmstat: move slab statistics from zone to
node counters") broke "Slab:" field of /proc/meminfo . It shows nearly
0kB"
In addition to /proc/meminfo, this problem also affects the slab
counters OOM/allocation failure info dumps, can cause early -ENOMEM from
overcommit protection, and miscalculate image size requirements during
suspend-to-disk.
This is because the patch in question switched the slab counters from
the zone level to the node level, but forgot to update the global
accessor functions to read the aggregate node data instead of the
aggregate zone data.
Use global_node_page_state() to access the global slab counters.
Fixes: 385386cff4 ("mm: vmstat: move slab statistics from zone to node counters")
Link: http://lkml.kernel.org/r/20170801134256.5400-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Stefan Agner <stefan@agner.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A while ago someone, and I cannot find the email just now, asked if we
could not implement the RECLAIM_FS inversion stuff with a 'fake' lock
like we use for other things like workqueues etc. I think this should
be possible which allows reducing the 'irq' states and will reduce the
amount of __bfs() lookups we do.
Removing the 1 IRQ state results in 4 less __bfs() walks per
dependency, improving lockdep performance. And by moving this
annotation out of the lockdep code it becomes easier for the mm people
to extend.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: iamjoonsoo.kim@lge.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Andre Wild reported the following warning:
WARNING: CPU: 2 PID: 1205 at kernel/cpu.c:240 lockdep_assert_cpus_held+0x4c/0x60
Modules linked in:
CPU: 2 PID: 1205 Comm: bash Not tainted 4.13.0-rc2-00022-gfd2b2c57ec20 #10
Hardware name: IBM 2964 N96 702 (z/VM 6.4.0)
task: 00000000701d8100 task.stack: 0000000073594000
Krnl PSW : 0704f00180000000 0000000000145e24 (lockdep_assert_cpus_held+0x4c/0x60)
...
Call Trace:
lockdep_assert_cpus_held+0x42/0x60)
stop_machine_cpuslocked+0x62/0xf0
build_all_zonelists+0x92/0x150
numa_zonelist_order_handler+0x102/0x150
proc_sys_call_handler.isra.12+0xda/0x118
proc_sys_write+0x34/0x48
__vfs_write+0x3c/0x178
vfs_write+0xbc/0x1a0
SyS_write+0x66/0xc0
system_call+0xc4/0x2b0
locks held by bash/1205:
#0: (sb_writers#4){.+.+.+}, at: vfs_write+0xa6/0x1a0
#1: (zl_order_mutex){+.+...}, at: numa_zonelist_order_handler+0x44/0x150
#2: (zonelists_mutex){+.+...}, at: numa_zonelist_order_handler+0xf4/0x150
Last Breaking-Event-Address:
lockdep_assert_cpus_held+0x48/0x60
This can be easily triggered with e.g.
echo n > /proc/sys/vm/numa_zonelist_order
In commit 3f906ba236 ("mm/memory-hotplug: switch locking to a percpu
rwsem") memory hotplug locking was changed to fix a potential deadlock.
This also switched the stop_machine() invocation within
build_all_zonelists() to stop_machine_cpuslocked() which now expects
that online cpus are locked when being called.
This assumption is not true if build_all_zonelists() is being called
from numa_zonelist_order_handler().
In order to fix this simply add a mem_hotplug_begin()/mem_hotplug_done()
pair to numa_zonelist_order_handler().
Link: http://lkml.kernel.org/r/20170726111738.38768-1-heiko.carstens@de.ibm.com
Fixes: 3f906ba236 ("mm/memory-hotplug: switch locking to a percpu rwsem")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reported-by: Andre Wild <wild@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__GFP_REPEAT was designed to allow retry-but-eventually-fail semantic to
the page allocator. This has been true but only for allocations
requests larger than PAGE_ALLOC_COSTLY_ORDER. It has been always
ignored for smaller sizes. This is a bit unfortunate because there is
no way to express the same semantic for those requests and they are
considered too important to fail so they might end up looping in the
page allocator for ever, similarly to GFP_NOFAIL requests.
Now that the whole tree has been cleaned up and accidental or misled
usage of __GFP_REPEAT flag has been removed for !costly requests we can
give the original flag a better name and more importantly a more useful
semantic. Let's rename it to __GFP_RETRY_MAYFAIL which tells the user
that the allocator would try really hard but there is no promise of a
success. This will work independent of the order and overrides the
default allocator behavior. Page allocator users have several levels of
guarantee vs. cost options (take GFP_KERNEL as an example)
- GFP_KERNEL & ~__GFP_RECLAIM - optimistic allocation without _any_
attempt to free memory at all. The most light weight mode which even
doesn't kick the background reclaim. Should be used carefully because
it might deplete the memory and the next user might hit the more
aggressive reclaim
- GFP_KERNEL & ~__GFP_DIRECT_RECLAIM (or GFP_NOWAIT)- optimistic
allocation without any attempt to free memory from the current
context but can wake kswapd to reclaim memory if the zone is below
the low watermark. Can be used from either atomic contexts or when
the request is a performance optimization and there is another
fallback for a slow path.
- (GFP_KERNEL|__GFP_HIGH) & ~__GFP_DIRECT_RECLAIM (aka GFP_ATOMIC) -
non sleeping allocation with an expensive fallback so it can access
some portion of memory reserves. Usually used from interrupt/bh
context with an expensive slow path fallback.
- GFP_KERNEL - both background and direct reclaim are allowed and the
_default_ page allocator behavior is used. That means that !costly
allocation requests are basically nofail but there is no guarantee of
that behavior so failures have to be checked properly by callers
(e.g. OOM killer victim is allowed to fail currently).
- GFP_KERNEL | __GFP_NORETRY - overrides the default allocator behavior
and all allocation requests fail early rather than cause disruptive
reclaim (one round of reclaim in this implementation). The OOM killer
is not invoked.
- GFP_KERNEL | __GFP_RETRY_MAYFAIL - overrides the default allocator
behavior and all allocation requests try really hard. The request
will fail if the reclaim cannot make any progress. The OOM killer
won't be triggered.
- GFP_KERNEL | __GFP_NOFAIL - overrides the default allocator behavior
and all allocation requests will loop endlessly until they succeed.
This might be really dangerous especially for larger orders.
Existing users of __GFP_REPEAT are changed to __GFP_RETRY_MAYFAIL
because they already had their semantic. No new users are added.
__alloc_pages_slowpath is changed to bail out for __GFP_RETRY_MAYFAIL if
there is no progress and we have already passed the OOM point.
This means that all the reclaim opportunities have been exhausted except
the most disruptive one (the OOM killer) and a user defined fallback
behavior is more sensible than keep retrying in the page allocator.
[akpm@linux-foundation.org: fix arch/sparc/kernel/mdesc.c]
[mhocko@suse.com: semantic fix]
Link: http://lkml.kernel.org/r/20170626123847.GM11534@dhcp22.suse.cz
[mhocko@kernel.org: address other thing spotted by Vlastimil]
Link: http://lkml.kernel.org/r/20170626124233.GN11534@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170623085345.11304-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Andrey reported a potential deadlock with the memory hotplug lock and
the cpu hotplug lock.
The reason is that memory hotplug takes the memory hotplug lock and then
calls stop_machine() which calls get_online_cpus(). That's the reverse
lock order to get_online_cpus(); get_online_mems(); in mm/slub_common.c
The problem has been there forever. The reason why this was never
reported is that the cpu hotplug locking had this homebrewn recursive
reader writer semaphore construct which due to the recursion evaded the
full lock dep coverage. The memory hotplug code copied that construct
verbatim and therefor has similar issues.
Three steps to fix this:
1) Convert the memory hotplug locking to a per cpu rwsem so the
potential issues get reported proper by lockdep.
2) Lock the online cpus in mem_hotplug_begin() before taking the memory
hotplug rwsem and use stop_machine_cpuslocked() in the page_alloc
code to avoid recursive locking.
3) The cpu hotpluck locking in #2 causes a recursive locking of the cpu
hotplug lock via __offline_pages() -> lru_add_drain_all(). Solve this
by invoking lru_add_drain_all_cpuslocked() instead.
Link: http://lkml.kernel.org/r/20170704093421.506836322@linutronix.de
Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since current_order starts as MAX_ORDER-1 and is then only decremented,
the second half of the loop condition seems superfluous. However, if
order is 0, we may decrement current_order past 0, making it UINT_MAX.
This is obviously too subtle ([1], [2]).
Since we need to add some comment anyway, change the two variables to
signed, making the counting-down for loop look more familiar, and
apparently also making gcc generate slightly smaller code.
[1] https://lkml.org/lkml/2016/6/20/493
[2] https://lkml.org/lkml/2017/6/19/345
[akpm@linux-foundation.org: fix up reject fixupping]
Link: http://lkml.kernel.org/r/20170621185529.2265-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reported-by: Hao Lee <haolee.swjtu@gmail.com>
Acked-by: Wei Yang <weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
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>
Since commit 3bc48f96cf ("mm, page_alloc: split smallest stolen page
in fallback") we pick the smallest (but sufficient) page of all that
have been stolen from a pageblock of different migratetype. However,
there are cases when we decide not to steal the whole pageblock.
Practically in the current implementation it means that we are trying to
fallback for a MIGRATE_MOVABLE allocation of order X, go through the
freelists from MAX_ORDER-1 down to X, and find free page of order Y. If
Y is less than pageblock_order / 2, we decide not to steal all pages
from the pageblock. When Y > X, it means we are potentially splitting a
larger page than we need, as there might be other pages of order Z,
where X <= Z < Y. Since Y is already too small to steal whole
pageblock, picking smallest available Z will result in the same decision
and we avoid splitting a higher-order page in a MIGRATE_UNMOVABLE or
MIGRATE_RECLAIMABLE pageblock.
This patch therefore changes the fallback algorithm so that in the
situation described above, we switch the fallback search strategy to go
from order X upwards to find the smallest suitable fallback. In theory
there shouldn't be a downside of this change wrt fragmentation.
This has been tested with mmtests' stress-highalloc performing
GFP_KERNEL order-4 allocations, here is the relevant extfrag tracepoint
statistics:
4.12.0-rc2 4.12.0-rc2
1-kernel4 2-kernel4
Page alloc extfrag event 25640976 69680977
Extfrag fragmenting 25621086 69661364
Extfrag fragmenting for unmovable 74409 73204
Extfrag fragmenting unmovable placed with movable 69003 67684
Extfrag fragmenting unmovable placed with reclaim. 5406 5520
Extfrag fragmenting for reclaimable 6398 8467
Extfrag fragmenting reclaimable placed with movable 869 884
Extfrag fragmenting reclaimable placed with unmov. 5529 7583
Extfrag fragmenting for movable 25540279 69579693
Since we force movable allocations to steal the smallest available page
(which we then practially always split), we steal less per fallback, so
the number of fallbacks increases and steals potentially happen from
different pageblocks. This is however not an issue for movable pages
that can be compacted.
Importantly, the "unmovable placed with movable" statistics is lower,
which is the result of less fragmentation in the unmovable pageblocks.
The effect on reclaimable allocation is a bit unclear.
Link: http://lkml.kernel.org/r/20170529093947.22618-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 20b2f52b73 ("numa: add CONFIG_MOVABLE_NODE for
movable-dedicated node") has introduced CONFIG_MOVABLE_NODE without a
good explanation on why it is actually useful.
It makes a lot of sense to make movable node semantic opt in but we
already have that because the feature has to be explicitly enabled on
the kernel command line. A config option on top only makes the
configuration space larger without a good reason. It also adds an
additional ifdefery that pollutes the code.
Just drop the config option and make it de-facto always enabled. This
shouldn't introduce any change to the semantic.
Link: http://lkml.kernel.org/r/20170529114141.536-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kani Toshimitsu <toshi.kani@hpe.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: per-lruvec slab stats"
Josef is working on a new approach to balancing slab caches and the page
cache. For this to work, he needs slab cache statistics on the lruvec
level. These patches implement that by adding infrastructure that
allows updating and reading generic VM stat items per lruvec, then
switches some existing VM accounting sites, including the slab
accounting ones, to this new cgroup-aware API.
I'll follow up with more patches on this, because there is actually
substantial simplification that can be done to the memory controller
when we replace private memcg accounting with making the existing VM
accounting sites cgroup-aware. But this is enough for Josef to base his
slab reclaim work on, so here goes.
This patch (of 5):
To re-implement slab cache vs. page cache balancing, we'll need the
slab counters at the lruvec level, which, ever since lru reclaim was
moved from the zone to the node, is the intersection of the node, not
the zone, and the memcg.
We could retain the per-zone counters for when the page allocator dumps
its memory information on failures, and have counters on both levels -
which on all but NUMA node 0 is usually redundant. But let's keep it
simple for now and just move them. If anybody complains we can restore
the per-zone counters.
[hannes@cmpxchg.org: fix oops]
Link: http://lkml.kernel.org/r/20170605183511.GA8915@cmpxchg.org
Link: http://lkml.kernel.org/r/20170530181724.27197-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The main allocator function __alloc_pages_nodemask() takes a zonelist
pointer as one of its parameters. All of its callers directly or
indirectly obtain the zonelist via node_zonelist() using a preferred
node id and gfp_mask. We can make the code a bit simpler by doing the
zonelist lookup in __alloc_pages_nodemask(), passing it a preferred node
id instead (gfp_mask is already another parameter).
There are some code size benefits thanks to removal of inlined
node_zonelist():
bloat-o-meter add/remove: 2/2 grow/shrink: 4/36 up/down: 399/-1351 (-952)
This will also make things simpler if we proceed with converting cpusets
to zonelists.
Link: http://lkml.kernel.org/r/20170517081140.30654-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.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>
I would like to stress that this patchset aims to fix issues and cleanup
the code *within the existing documented semantics*, i.e. patch 1
ignores mempolicy restrictions if the set of allowed nodes has no
intersection with set of nodes allowed by cpuset. I believe discussing
potential changes of the semantics can be better done once we have a
baseline with no known bugs of the current semantics.
I've recently summarized the cpuset/mempolicy issues in a LSF/MM
proposal [1] and the discussion itself [2]. I've been trying to rewrite
the handling as proposed, with the idea that changing semantics to make
all mempolicies static wrt cpuset updates (and discarding the relative
and default modes) can be tried on top, as there's a high risk of being
rejected/reverted because somebody might still care about the removed
modes.
However I haven't yet figured out how to properly:
1) make mempolicies swappable instead of rebinding in place. I thought
mbind() already works that way and uses refcounting to avoid
use-after-free of the old policy by a parallel allocation, but turns
out true refcounting is only done for shared (shmem) mempolicies, and
the actual protection for mbind() comes from mmap_sem. Extending the
refcounting means more overhead in allocator hot path. Also swapping
whole mempolicies means that we have to allocate the new ones, which
can fail, and reverting of the partially done work also means
allocating (note that mbind() doesn't care and will just leave part
of the range updated and part not updated when returning -ENOMEM...).
2) make cpuset's task->mems_allowed also swappable (after converting it
from nodemask to zonelist, which is the easy part) for mostly the
same reasons.
The good news is that while trying to do the above, I've at least
figured out how to hopefully close the remaining premature OOM's, and do
a buch of cleanups on top, removing quite some of the code that was also
supposed to prevent the cpuset update races, but doesn't work anymore
nowadays. This should fix the most pressing concerns with this topic
and give us a better baseline before either proceeding with the original
proposal, or pushing a change of semantics that removes the problem 1)
above. I'd be then fine with trying to change the semantic first and
rewrite later.
Patchset has been tested with the LTP cpuset01 stress test.
[1] https://lkml.kernel.org/r/4c44a589-5fd8-08d0-892c-e893bb525b71@suse.cz
[2] https://lwn.net/Articles/717797/
[3] https://marc.info/?l=linux-mm&m=149191957922828&w=2
This patch (of 6):
Commit e47483bca2 ("mm, page_alloc: fix premature OOM when racing with
cpuset mems update") has fixed known recent regressions found by LTP's
cpuset01 testcase. I have however found that by modifying the testcase
to use per-vma mempolicies via bind(2) instead of per-task mempolicies
via set_mempolicy(2), the premature OOM still happens and the issue is
much older.
The root of the problem is that the cpuset's mems_allowed and
mempolicy's nodemask can temporarily have no intersection, thus
get_page_from_freelist() cannot find any usable zone. The current
semantic for empty intersection is to ignore mempolicy's nodemask and
honour cpuset restrictions. This is checked in node_zonelist(), but the
racy update can happen after we already passed the check. Such races
should be protected by the seqlock task->mems_allowed_seq, but it
doesn't work here, because 1) mpol_rebind_mm() does not happen under
seqlock for write, and doing so would lead to deadlock, as it takes
mmap_sem for write, while the allocation can have mmap_sem for read when
it's taking the seqlock for read. And 2) the seqlock cookie of callers
of node_zonelist() (alloc_pages_vma() and alloc_pages_current()) is
different than the one of __alloc_pages_slowpath(), so there's still a
potential race window.
This patch fixes the issue by having __alloc_pages_slowpath() check for
empty intersection of cpuset and ac->nodemask before OOM or allocation
failure. If it's indeed empty, the nodemask is ignored and allocation
retried, which mimics node_zonelist(). This works fine, because almost
all callers of __alloc_pages_nodemask are obtaining the nodemask via
node_zonelist(). The only exception is new_node_page() from hotplug,
where the potential violation of nodemask isn't an issue, as there's
already a fallback allocation attempt without any nodemask. If there's
a future caller that needs to have its specific nodemask honoured over
task's cpuset restrictions, we'll have to e.g. add a gfp flag for that.
Link: http://lkml.kernel.org/r/20170517081140.30654-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The functions are not used in some configurations. Adding the attribute
fixes the following warnings when building with clang:
mm/page_alloc.c:409:19: error: function 'bad_range' is not needed and
will not be emitted [-Werror,-Wunneeded-internal-declaration]
mm/page_alloc.c:1106:30: error: unused function 'meminit_pfn_in_nid'
[-Werror,-Wunused-function]
Link: http://lkml.kernel.org/r/20170518182030.165633-1-mka@chromium.org
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow hash tables to scale with memory but at slower pace, when
HASH_ADAPT is provided every time memory quadruples the sizes of hash
tables will only double instead of quadrupling as well. This algorithm
starts working only when memory size reaches a certain point, currently
set to 64G.
This is example of dentry hash table size, before and after four various
memory configurations:
MEMORY SCALE HASH_SIZE
old new old new
8G 13 13 8M 8M
16G 13 13 16M 16M
32G 13 13 32M 32M
64G 13 13 64M 64M
128G 13 14 128M 64M
256G 13 14 256M 128M
512G 13 15 512M 128M
1024G 13 15 1024M 256M
2048G 13 16 2048M 256M
4096G 13 16 4096M 512M
8192G 13 17 8192M 512M
16384G 13 17 16384M 1024M
32768G 13 18 32768M 1024M
65536G 13 18 65536M 2048M
The effect of this change on runtime is undetectable as filesystem
growth is not proportional to machine memory size as is currently
assumed. The change effects only large memory machine. Additional
tuning might be needed, but that can be done by the clients of the
kmem_cache_create interface, not the generic cache allocator itself.
The adaptive hashing is disabled on 32 bit systems to avoid confusion of
whether base should be different for smaller systems, and to avoid
overflows.
[mhocko@suse.com: drop HASH_ADAPT]
Link: http://lkml.kernel.org/r/20170509094607.GG6481@dhcp22.suse.cz
[pasha.tatashin@oracle.com: UL -> ULL fix]
Link: http://lkml.kernel.org/r/1495300013-653283-2-git-send-email-pasha.tatashin@oracle.com
[pasha.tatashin@oracle.com: disable adaptive hash on 32 bit systems]
Link: http://lkml.kernel.org/r/1495469329-755807-2-git-send-email-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/1488432825-92126-5-git-send-email-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Babu Moger <babu.moger@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new flag HASH_ZERO which when provided grantees that the hash
table that is returned by alloc_large_system_hash() is zeroed. In most
cases that is what is needed by the caller. Use page level allocator's
__GFP_ZERO flags to zero the memory. It is using memset() which is
efficient method to zero memory and is optimized for most platforms.
Link: http://lkml.kernel.org/r/1488432825-92126-3-git-send-email-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__pageblock_pfn_to_page has two users currently, set_zone_contiguous
which checks whether the given zone contains holes and
pageblock_pfn_to_page which then carefully returns a first valid page
from the given pfn range for the given zone. This doesn't handle zones
which are not fully populated though. Memory pageblocks can be offlined
or might not have been onlined yet. In such a case the zone should be
considered to have holes otherwise pfn walkers can touch and play with
offline pages.
Current callers of pageblock_pfn_to_page in compaction seem to work
properly right now because they only isolate PageBuddy
(isolate_freepages_block) or PageLRU resp. __PageMovable
(isolate_migratepages_block) which will be always false for these pages.
It would be safer to skip these pages altogether, though.
In order to do this patch adds a new memory section state
(SECTION_IS_ONLINE) which is set in memory_present (during boot time) or
in online_pages_range during the memory hotplug. Similarly
offline_mem_sections clears the bit and it is called when the memory
range is offlined.
pfn_to_online_page helper is then added which check the mem section and
only returns a page if it is onlined already.
Use the new helper in __pageblock_pfn_to_page and skip the whole page
block in such a case.
[mhocko@suse.com: check valid section number in pfn_to_online_page (Vlastimil),
mark sections online after all struct pages are initialized in
online_pages_range (Vlastimil)]
Link: http://lkml.kernel.org/r/20170518164210.GD18333@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170515085827.16474-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: make movable onlining suck less", v4.
Movable onlining is a real hack with many downsides - mainly
reintroduction of lowmem/highmem issues we used to have on 32b systems -
but it is the only way to make the memory hotremove more reliable which
is something that people are asking for.
The current semantic of memory movable onlinening is really cumbersome,
however. The main reason for this is that the udev driven approach is
basically unusable because udev races with the memory probing while only
the last memory block or the one adjacent to the existing zone_movable
are allowed to be onlined movable. In short the criterion for the
successful online_movable changes under udev's feet. A reliable udev
approach would require a 2 phase approach where the first successful
movable online would have to check all the previous blocks and online
them in descending order. This is hard to be considered sane.
This patchset aims at making the onlining semantic more usable. First
of all it allows to online memory movable as long as it doesn't clash
with the existing ZONE_NORMAL. That means that ZONE_NORMAL and
ZONE_MOVABLE cannot overlap. Currently I preserve the original ordering
semantic so the zone always precedes the movable zone but I have plans
to remove this restriction in future because it is not really necessary.
First 3 patches are cleanups which should be ready to be merged right
away (unless I have missed something subtle of course).
Patch 4 deals with ZONE_DEVICE dependencies down the __add_pages path.
Patch 5 deals with implicit assumptions of register_one_node on pgdat
initialization.
Patches 6-10 deal with offline holes in the zone for pfn walkers. I
hope I got all of them right but people familiar with compaction should
double check this.
Patch 11 is the core of the change. In order to make it easier to
review I have tried it to be as minimalistic as possible and the large
code removal is moved to patch 14.
Patch 12 is a trivial follow up cleanup. Patch 13 fixes sparse warnings
and finally patch 14 removes the unused code.
I have tested the patches in kvm:
# qemu-system-x86_64 -enable-kvm -monitor pty -m 2G,slots=4,maxmem=4G -numa node,mem=1G -numa node,mem=1G ...
and then probed the additional memory by
(qemu) object_add memory-backend-ram,id=mem1,size=1G
(qemu) device_add pc-dimm,id=dimm1,memdev=mem1
Then I have used this simple script to probe the memory block by hand
# cat probe_memblock.sh
#!/bin/sh
BLOCK_NR=$1
# echo $((0x100000000+$BLOCK_NR*(128<<20))) > /sys/devices/system/memory/probe
# for i in $(seq 10); do sh probe_memblock.sh $i; done
# grep . /sys/devices/system/memory/memory3?/valid_zones 2>/dev/null
/sys/devices/system/memory/memory33/valid_zones:Normal Movable
/sys/devices/system/memory/memory34/valid_zones:Normal Movable
/sys/devices/system/memory/memory35/valid_zones:Normal Movable
/sys/devices/system/memory/memory36/valid_zones:Normal Movable
/sys/devices/system/memory/memory37/valid_zones:Normal Movable
/sys/devices/system/memory/memory38/valid_zones:Normal Movable
/sys/devices/system/memory/memory39/valid_zones:Normal Movable
The main difference to the original implementation is that all new
memblocks can be both online_kernel and online_movable initially because
there is no clash obviously. For the comparison the original
implementation would have
/sys/devices/system/memory/memory33/valid_zones:Normal
/sys/devices/system/memory/memory34/valid_zones:Normal
/sys/devices/system/memory/memory35/valid_zones:Normal
/sys/devices/system/memory/memory36/valid_zones:Normal
/sys/devices/system/memory/memory37/valid_zones:Normal
/sys/devices/system/memory/memory38/valid_zones:Normal
/sys/devices/system/memory/memory39/valid_zones:Normal Movable
Now
# echo online_movable > /sys/devices/system/memory/memory34/state
# grep . /sys/devices/system/memory/memory3?/valid_zones 2>/dev/null
/sys/devices/system/memory/memory33/valid_zones:Normal Movable
/sys/devices/system/memory/memory34/valid_zones:Movable
/sys/devices/system/memory/memory35/valid_zones:Movable
/sys/devices/system/memory/memory36/valid_zones:Movable
/sys/devices/system/memory/memory37/valid_zones:Movable
/sys/devices/system/memory/memory38/valid_zones:Movable
/sys/devices/system/memory/memory39/valid_zones:Movable
Block 33 can still be online both kernel and movable while all
the remaining can be only movable.
/proc/zonelist says
Node 0, zone Normal
pages free 0
min 0
low 0
high 0
spanned 0
present 0
--
Node 0, zone Movable
pages free 32753
min 85
low 117
high 149
spanned 32768
present 32768
A new memblock at a lower address will result in a new memblock (32)
which will still allow both Normal and Movable.
# sh probe_memblock.sh 0
# grep . /sys/devices/system/memory/memory3[2-5]/valid_zones 2>/dev/null
/sys/devices/system/memory/memory32/valid_zones:Normal Movable
/sys/devices/system/memory/memory33/valid_zones:Normal Movable
/sys/devices/system/memory/memory34/valid_zones:Movable
/sys/devices/system/memory/memory35/valid_zones:Movable
and online_kernel will convert it to the zone normal properly
while 33 can be still onlined both ways.
# echo online_kernel > /sys/devices/system/memory/memory32/state
# grep . /sys/devices/system/memory/memory3[2-5]/valid_zones 2>/dev/null
/sys/devices/system/memory/memory32/valid_zones:Normal
/sys/devices/system/memory/memory33/valid_zones:Normal Movable
/sys/devices/system/memory/memory34/valid_zones:Movable
/sys/devices/system/memory/memory35/valid_zones:Movable
/proc/zoneinfo will now tell
Node 0, zone Normal
pages free 65441
min 165
low 230
high 295
spanned 65536
present 65536
--
Node 0, zone Movable
pages free 32740
min 82
low 114
high 146
spanned 32768
present 32768
so both zones have one memblock spanned and present.
Onlining 39 should associate this block to the movable zone
# echo online > /sys/devices/system/memory/memory39/state
/proc/zoneinfo will now tell
Node 0, zone Normal
pages free 32765
min 80
low 112
high 144
spanned 32768
present 32768
--
Node 0, zone Movable
pages free 65501
min 160
low 225
high 290
spanned 196608
present 65536
so we will have a movable zone which spans 6 memblocks, 2 present and 4
representing a hole.
Offlining both movable blocks will lead to the zone with no present
pages which is the expected behavior I believe.
# echo offline > /sys/devices/system/memory/memory39/state
# echo offline > /sys/devices/system/memory/memory34/state
# grep -A6 "Movable\|Normal" /proc/zoneinfo
Node 0, zone Normal
pages free 32735
min 90
low 122
high 154
spanned 32768
present 32768
--
Node 0, zone Movable
pages free 0
min 0
low 0
high 0
spanned 196608
present 0
As a bonus we will get a nice cleanup in the memory hotplug codebase.
This patch (of 16):
init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.
This patch shouldn't have any visible effect
Link: http://lkml.kernel.org/r/20170515085827.16474-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have seen an early OOM killer invocation on ppc64 systems with
crashkernel=4096M:
kthreadd invoked oom-killer: gfp_mask=0x16040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK), nodemask=7, order=0, oom_score_adj=0
kthreadd cpuset=/ mems_allowed=7
CPU: 0 PID: 2 Comm: kthreadd Not tainted 4.4.68-1.gd7fe927-default #1
Call Trace:
dump_stack+0xb0/0xf0 (unreliable)
dump_header+0xb0/0x258
out_of_memory+0x5f0/0x640
__alloc_pages_nodemask+0xa8c/0xc80
kmem_getpages+0x84/0x1a0
fallback_alloc+0x2a4/0x320
kmem_cache_alloc_node+0xc0/0x2e0
copy_process.isra.25+0x260/0x1b30
_do_fork+0x94/0x470
kernel_thread+0x48/0x60
kthreadd+0x264/0x330
ret_from_kernel_thread+0x5c/0xa4
Mem-Info:
active_anon:0 inactive_anon:0 isolated_anon:0
active_file:0 inactive_file:0 isolated_file:0
unevictable:0 dirty:0 writeback:0 unstable:0
slab_reclaimable:5 slab_unreclaimable:73
mapped:0 shmem:0 pagetables:0 bounce:0
free:0 free_pcp:0 free_cma:0
Node 7 DMA free:0kB min:0kB low:0kB high:0kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:52428800kB managed:110016kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:320kB slab_unreclaimable:4672kB kernel_stack:1152kB pagetables:0kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
lowmem_reserve[]: 0 0 0 0
Node 7 DMA: 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB 0*8192kB 0*16384kB = 0kB
0 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap = 0kB
Total swap = 0kB
819200 pages RAM
0 pages HighMem/MovableOnly
817481 pages reserved
0 pages cma reserved
0 pages hwpoisoned
the reason is that the managed memory is too low (only 110MB) while the
rest of the the 50GB is still waiting for the deferred intialization to
be done. update_defer_init estimates the initial memoty to initialize
to 2GB at least but it doesn't consider any memory allocated in that
range. In this particular case we've had
Reserving 4096MB of memory at 128MB for crashkernel (System RAM: 51200MB)
so the low 2GB is mostly depleted.
Fix this by considering memblock allocations in the initial static
initialization estimation. Move the max_initialise to
reset_deferred_meminit and implement a simple memblock_reserved_memory
helper which iterates all reserved blocks and sums the size of all that
start below the given address. The cumulative size is than added on top
of the initial estimation. This is still not ideal because
reset_deferred_meminit doesn't consider holes and so reservation might
be above the initial estimation whihch we ignore but let's make the
logic simpler until we really need to handle more complicated cases.
Fixes: 3a80a7fa79 ("mm: meminit: initialise a subset of struct pages if CONFIG_DEFERRED_STRUCT_PAGE_INIT is set")
Link: http://lkml.kernel.org/r/20170531104010.GI27783@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> [4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Roman Gushchin has reported that the OOM killer can trivially selects
next OOM victim when a thread doing memory allocation from page fault
path was selected as first OOM victim.
allocate invoked oom-killer: gfp_mask=0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null), order=0, oom_score_adj=0
allocate cpuset=/ mems_allowed=0
CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
oom_kill_process+0x219/0x3e0
out_of_memory+0x11d/0x480
__alloc_pages_slowpath+0xc84/0xd40
__alloc_pages_nodemask+0x245/0x260
alloc_pages_vma+0xa2/0x270
__handle_mm_fault+0xca9/0x10c0
handle_mm_fault+0xf3/0x210
__do_page_fault+0x240/0x4e0
trace_do_page_fault+0x37/0xe0
do_async_page_fault+0x19/0x70
async_page_fault+0x28/0x30
...
Out of memory: Kill process 492 (allocate) score 899 or sacrifice child
Killed process 492 (allocate) total-vm:2052368kB, anon-rss:1894576kB, file-rss:4kB, shmem-rss:0kB
allocate: page allocation failure: order:0, mode:0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null)
allocate cpuset=/ mems_allowed=0
CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
__alloc_pages_slowpath+0xd32/0xd40
__alloc_pages_nodemask+0x245/0x260
alloc_pages_vma+0xa2/0x270
__handle_mm_fault+0xca9/0x10c0
handle_mm_fault+0xf3/0x210
__do_page_fault+0x240/0x4e0
trace_do_page_fault+0x37/0xe0
do_async_page_fault+0x19/0x70
async_page_fault+0x28/0x30
...
oom_reaper: reaped process 492 (allocate), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
...
allocate invoked oom-killer: gfp_mask=0x0(), nodemask=(null), order=0, oom_score_adj=0
allocate cpuset=/ mems_allowed=0
CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
oom_kill_process+0x219/0x3e0
out_of_memory+0x11d/0x480
pagefault_out_of_memory+0x68/0x80
mm_fault_error+0x8f/0x190
? handle_mm_fault+0xf3/0x210
__do_page_fault+0x4b2/0x4e0
trace_do_page_fault+0x37/0xe0
do_async_page_fault+0x19/0x70
async_page_fault+0x28/0x30
...
Out of memory: Kill process 233 (firewalld) score 10 or sacrifice child
Killed process 233 (firewalld) total-vm:246076kB, anon-rss:20956kB, file-rss:0kB, shmem-rss:0kB
There is a race window that the OOM reaper completes reclaiming the
first victim's memory while nothing but mutex_trylock() prevents the
first victim from calling out_of_memory() from pagefault_out_of_memory()
after memory allocation for page fault path failed due to being selected
as an OOM victim.
This is a side effect of commit 9a67f6488e ("mm: consolidate
GFP_NOFAIL checks in the allocator slowpath") because that commit
silently changed the behavior from
/* Avoid allocations with no watermarks from looping endlessly */
to
/*
* Give up allocations without trying memory reserves if selected
* as an OOM victim
*/
in __alloc_pages_slowpath() by moving the location to check TIF_MEMDIE
flag. I have noticed this change but I didn't post a patch because I
thought it is an acceptable change other than noise by warn_alloc()
because !__GFP_NOFAIL allocations are allowed to fail. But we
overlooked that failing memory allocation from page fault path makes
difference due to the race window explained above.
While it might be possible to add a check to pagefault_out_of_memory()
that prevents the first victim from calling out_of_memory() or remove
out_of_memory() from pagefault_out_of_memory(), changing
pagefault_out_of_memory() does not suppress noise by warn_alloc() when
allocating thread was selected as an OOM victim. There is little point
with printing similar backtraces and memory information from both
out_of_memory() and warn_alloc().
Instead, if we guarantee that current thread can try allocations with no
watermarks once when current thread looping inside
__alloc_pages_slowpath() was selected as an OOM victim, we can follow "who
can use memory reserves" rules and suppress noise by warn_alloc() and
prevent memory allocations from page fault path from calling
pagefault_out_of_memory().
If we take the comment literally, this patch would do
- if (test_thread_flag(TIF_MEMDIE))
- goto nopage;
+ if (alloc_flags == ALLOC_NO_WATERMARKS || (gfp_mask & __GFP_NOMEMALLOC))
+ goto nopage;
because gfp_pfmemalloc_allowed() returns false if __GFP_NOMEMALLOC is
given. But if I recall correctly (I couldn't find the message), the
condition is meant to apply to only OOM victims despite the comment.
Therefore, this patch preserves TIF_MEMDIE check.
Fixes: 9a67f6488e ("mm: consolidate GFP_NOFAIL checks in the allocator slowpath")
Link: http://lkml.kernel.org/r/201705192112.IAF69238.OQOHSJLFOFFMtV@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Roman Gushchin <guro@fb.com>
Tested-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org> [4.11]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The previous patch ("mm: prevent potential recursive reclaim due to
clearing PF_MEMALLOC") has shown that simply setting and clearing
PF_MEMALLOC in current->flags can result in wrongly clearing a
pre-existing PF_MEMALLOC flag and potentially lead to recursive reclaim.
Let's introduce helpers that support proper nesting by saving the
previous stat of the flag, similar to the existing memalloc_noio_* and
memalloc_nofs_* helpers. Convert existing setting/clearing of
PF_MEMALLOC within mm to the new helpers.
There are no known issues with the converted code, but the change makes
it more robust.
Link: http://lkml.kernel.org/r/20170405074700.29871-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Chris Leech <cleech@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Lee Duncan <lduncan@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "more robust PF_MEMALLOC handling"
This series aims to unify the setting and clearing of PF_MEMALLOC, which
prevents recursive reclaim. There are some places that clear the flag
unconditionally from current->flags, which may result in clearing a
pre-existing flag. This already resulted in a bug report that Patch 1
fixes (without the new helpers, to make backporting easier). Patch 2
introduces the new helpers, modelled after existing memalloc_noio_* and
memalloc_nofs_* helpers, and converts mm core to use them. Patches 3
and 4 convert non-mm code.
This patch (of 4):
__alloc_pages_direct_compact() sets PF_MEMALLOC to prevent deadlock
during page migration by lock_page() (see the comment in
__unmap_and_move()). Then it unconditionally clears the flag, which can
clear a pre-existing PF_MEMALLOC flag and result in recursive reclaim.
This was not a problem until commit a8161d1ed6 ("mm, page_alloc:
restructure direct compaction handling in slowpath"), because direct
compation was called only after direct reclaim, which was skipped when
PF_MEMALLOC flag was set.
Even now it's only a theoretical issue, as the new callsite of
__alloc_pages_direct_compact() is reached only for costly orders and
when gfp_pfmemalloc_allowed() is true, which means either
__GFP_NOMEMALLOC is in gfp_flags or in_interrupt() is true. There is no
such known context, but let's play it safe and make
__alloc_pages_direct_compact() robust for cases where PF_MEMALLOC is
already set.
Fixes: a8161d1ed6 ("mm, page_alloc: restructure direct compaction handling in slowpath")
Link: http://lkml.kernel.org/r/20170405074700.29871-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Chris Leech <cleech@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Lee Duncan <lduncan@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The migrate scanner in async compaction is currently limited to
MIGRATE_MOVABLE pageblocks. This is a heuristic intended to reduce
latency, based on the assumption that non-MOVABLE pageblocks are
unlikely to contain movable pages.
However, with the exception of THP's, most high-order allocations are
not movable. Should the async compaction succeed, this increases the
chance that the non-MOVABLE allocations will fallback to a MOVABLE
pageblock, making the long-term fragmentation worse.
This patch attempts to help the situation by changing async direct
compaction so that the migrate scanner only scans the pageblocks of the
requested migratetype. If it's a non-MOVABLE type and there are such
pageblocks that do contain movable pages, chances are that the
allocation can succeed within one of such pageblocks, removing the need
for a fallback. If that fails, the subsequent sync attempt will ignore
this restriction.
In testing based on 4.9 kernel with stress-highalloc from mmtests
configured for order-4 GFP_KERNEL allocations, this patch has reduced
the number of unmovable allocations falling back to movable pageblocks
by 30%. The number of movable allocations falling back is reduced by
12%.
Link: http://lkml.kernel.org/r/20170307131545.28577-8-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When stealing pages from pageblock of a different migratetype, we count
how many free pages were stolen, and change the pageblock's migratetype
if more than half of the pageblock was free. This might be too
conservative, as there might be other pages that are not free, but were
allocated with the same migratetype as our allocation requested.
While we cannot determine the migratetype of allocated pages precisely
(at least without the page_owner functionality enabled), we can count
pages that compaction would try to isolate for migration - those are
either on LRU or __PageMovable(). The rest can be assumed to be
MIGRATE_RECLAIMABLE or MIGRATE_UNMOVABLE, which we cannot easily
distinguish. This counting can be done as part of free page stealing
with little additional overhead.
The page stealing code is changed so that it considers free pages plus
pages of the "good" migratetype for the decision whether to change
pageblock's migratetype.
The result should be more accurate migratetype of pageblocks wrt the
actual pages in the pageblocks, when stealing from semi-occupied
pageblocks. This should help the efficiency of page grouping by
mobility.
In testing based on 4.9 kernel with stress-highalloc from mmtests
configured for order-4 GFP_KERNEL allocations, this patch has reduced
the number of unmovable allocations falling back to movable pageblocks
by 47%. The number of movable allocations falling back to other
pageblocks are increased by 55%, but these events don't cause permanent
fragmentation, so the tradeoff should be positive. Later patches also
offset the movable fallback increase to some extent.
[akpm@linux-foundation.org: merge fix]
Link: http://lkml.kernel.org/r/20170307131545.28577-5-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __rmqueue_fallback() function is called when there's no free page of
requested migratetype, and we need to steal from a different one.
There are various heuristics to make this event infrequent and reduce
permanent fragmentation. The main one is to try stealing from a
pageblock that has the most free pages, and possibly steal them all at
once and convert the whole pageblock. Precise searching for such
pageblock would be expensive, so instead the heuristics walks the free
lists from MAX_ORDER down to requested order and assumes that the block
with highest-order free page is likely to also have the most free pages
in total.
Chances are that together with the highest-order page, we steal also
pages of lower orders from the same block. But then we still split the
highest order page. This is wasteful and can contribute to
fragmentation instead of avoiding it.
This patch thus changes __rmqueue_fallback() to just steal the page(s)
and put them on the freelist of the requested migratetype, and only
report whether it was successful. Then we pick (and eventually split)
the smallest page with __rmqueue_smallest(). This all happens under
zone lock, so nobody can steal it from us in the process. This should
reduce fragmentation due to fallbacks. At worst we are only stealing a
single highest-order page and waste some cycles by moving it between
lists and then removing it, but fallback is not exactly hot path so that
should not be a concern. As a side benefit the patch removes some
duplicate code by reusing __rmqueue_smallest().
[vbabka@suse.cz: fix endless loop in the modified __rmqueue()]
Link: http://lkml.kernel.org/r/59d71b35-d556-4fc9-ee2e-1574259282fd@suse.cz
Link: http://lkml.kernel.org/r/20170307131545.28577-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
o Pretty much a full rewrite of the processing of function plugins.
i.e. echo do_IRQ:stacktrace > set_ftrace_filter
o The rewrite was needed to add plugins to be unique to tracing instances.
i.e. mkdir instance/foo; cd instances/foo; echo do_IRQ:stacktrace > set_ftrace_filter
The old way was written very hacky. This removes a lot of those hacks.
o New "function-fork" tracing option. When set, pids in the set_ftrace_pid
will have their children added when the processes with their pids
listed in the set_ftrace_pid file forks.
o Exposure of "maxactive" for kretprobe in kprobe_events
o Allow for builtin init functions to be traced by the function tracer
(via the kernel command line). Module init function tracing will come
in the next release.
o Added more selftests, and have selftests also test in an instance.
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Merge tag 'trace-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"New features for this release:
- Pretty much a full rewrite of the processing of function plugins.
i.e. echo do_IRQ:stacktrace > set_ftrace_filter
- The rewrite was needed to add plugins to be unique to tracing
instances. i.e. mkdir instance/foo; cd instances/foo; echo
do_IRQ:stacktrace > set_ftrace_filter The old way was written very
hacky. This removes a lot of those hacks.
- New "function-fork" tracing option. When set, pids in the
set_ftrace_pid will have their children added when the processes
with their pids listed in the set_ftrace_pid file forks.
- Exposure of "maxactive" for kretprobe in kprobe_events
- Allow for builtin init functions to be traced by the function
tracer (via the kernel command line). Module init function tracing
will come in the next release.
- Added more selftests, and have selftests also test in an instance"
* tag 'trace-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (60 commits)
ring-buffer: Return reader page back into existing ring buffer
selftests: ftrace: Allow some event trigger tests to run in an instance
selftests: ftrace: Have some basic tests run in a tracing instance too
selftests: ftrace: Have event tests also run in an tracing instance
selftests: ftrace: Make func_event_triggers and func_traceonoff_triggers tests do instances
selftests: ftrace: Allow some tests to be run in a tracing instance
tracing/ftrace: Allow for instances to trigger their own stacktrace probes
tracing/ftrace: Allow for the traceonoff probe be unique to instances
tracing/ftrace: Enable snapshot function trigger to work with instances
tracing/ftrace: Allow instances to have their own function probes
tracing/ftrace: Add a better way to pass data via the probe functions
ftrace: Dynamically create the probe ftrace_ops for the trace_array
tracing: Pass the trace_array into ftrace_probe_ops functions
tracing: Have the trace_array hold the list of registered func probes
ftrace: If the hash for a probe fails to update then free what was initialized
ftrace: Have the function probes call their own function
ftrace: Have each function probe use its own ftrace_ops
ftrace: Have unregister_ftrace_function_probe_func() return a value
ftrace: Add helper function ftrace_hash_move_and_update_ops()
ftrace: Remove data field from ftrace_func_probe structure
...
Commit c0a32fc5a2 ("mm: more intensive memory corruption debugging")
changed to check debug_guardpage_minorder() > 0 when reporting
allocation failures. The reasoning was
When we use guard page to debug memory corruption, it shrinks
available pages to 1/2, 1/4, 1/8 and so on, depending on parameter
value. In such case memory allocation failures can be common and
printing errors can flood dmesg. If somebody debug corruption,
allocation failures are not the things he/she is interested about.
but this is misguided.
Allocation requests with __GFP_NOWARN flag by definition do not cause
flooding of allocation failure messages. Allocation requests with
__GFP_NORETRY flag likely also have __GFP_NOWARN flag. Costly
allocation requests likely also have __GFP_NOWARN flag.
Allocation requests without __GFP_DIRECT_RECLAIM flag likely also have
__GFP_NOWARN flag or __GFP_HIGH flag. Non-costly allocation requests
with __GFP_DIRECT_RECLAIM flag basically retry forever due to the "too
small to fail" memory-allocation rule.
Therefore, as a whole, shrinking available pages by
debug_guardpage_minorder= kernel boot parameter might cause flooding of
OOM killer messages but unlikely causes flooding of allocation failure
messages. Let's remove debug_guardpage_minorder() > 0 check which would
likely be pointless.
Link: http://lkml.kernel.org/r/1491910035-4231-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On SPARSEMEM systems page poisoning is enabled after buddy is up,
because of the dependency on page extension init. This causes the pages
released by free_all_bootmem not to be poisoned. This either delays or
misses the identification of some issues because the pages have to
undergo another cycle of alloc-free-alloc for any corruption to be
detected.
Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON
flag. Since all the free pages will now be poisoned, the flag need not
be verified before checking the poison during an alloc.
[vinmenon@codeaurora.org: fix Kconfig]
Link: http://lkml.kernel.org/r/1490878002-14423-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__GFP_NOWARN, which is usually added to avoid warnings from callsites
that expect to fail and have fallbacks, currently also suppresses
allocation stall warnings. These trigger when an allocation is stuck
inside the allocator for 10 seconds or longer.
But there is no class of allocations that can get legitimately stuck in
the allocator for this long. This always indicates a problem.
Always emit stall warnings. Restrict __GFP_NOWARN to alloc failures.
Link: http://lkml.kernel.org/r/20170125181150.GA16398@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
GFP_NOFS context is used for the following 5 reasons currently:
- to prevent from deadlocks when the lock held by the allocation
context would be needed during the memory reclaim
- to prevent from stack overflows during the reclaim because the
allocation is performed from a deep context already
- to prevent lockups when the allocation context depends on other
reclaimers to make a forward progress indirectly
- just in case because this would be safe from the fs POV
- silence lockdep false positives
Unfortunately overuse of this allocation context brings some problems to
the MM. Memory reclaim is much weaker (especially during heavy FS
metadata workloads), OOM killer cannot be invoked because the MM layer
doesn't have enough information about how much memory is freeable by the
FS layer.
In many cases it is far from clear why the weaker context is even used
and so it might be used unnecessarily. We would like to get rid of
those as much as possible. One way to do that is to use the flag in
scopes rather than isolated cases. Such a scope is declared when really
necessary, tracked per task and all the allocation requests from within
the context will simply inherit the GFP_NOFS semantic.
Not only this is easier to understand and maintain because there are
much less problematic contexts than specific allocation requests, this
also helps code paths where FS layer interacts with other layers (e.g.
crypto, security modules, MM etc...) and there is no easy way to convey
the allocation context between the layers.
Introduce memalloc_nofs_{save,restore} API to control the scope of
GFP_NOFS allocation context. This is basically copying
memalloc_noio_{save,restore} API we have for other restricted allocation
context GFP_NOIO. The PF_MEMALLOC_NOFS flag already exists and it is
just an alias for PF_FSTRANS which has been xfs specific until recently.
There are no more PF_FSTRANS users anymore so let's just drop it.
PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS
implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO. memalloc_noio_flags
is renamed to current_gfp_context because it now cares about both
PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts. Xfs code paths preserve
their semantic. kmem_flags_convert() doesn't need to evaluate the flag
anymore.
This patch shouldn't introduce any functional changes.
Let's hope that filesystems will drop direct GFP_NOFS (resp. ~__GFP_FS)
usage as much as possible and only use a properly documented
memalloc_nofs_{save,restore} checkpoints where they are appropriate.
[akpm@linux-foundation.org: fix comment typo, reflow comment]
Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.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>
Introduce two helpers, is_migrate_highatomic() and is_migrate_highatomic_page().
Simplify the code, no functional changes.
[akpm@linux-foundation.org: use static inlines rather than macros, per mhocko]
Link: http://lkml.kernel.org/r/58B94F15.6060606@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@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>
The backoff mechanism is not needed. If we have MAX_RECLAIM_RETRIES
loops without progress, we'll OOM anyway; backing off might cut one or
two iterations off that in the rare OOM case. If we have intermittent
success reclaiming a few pages, the backoff function gets reset also,
and so is of little help in these scenarios.
We might want a backoff function for when there IS progress, but not
enough to be satisfactory. But this isn't that. Remove it.
Link: http://lkml.kernel.org/r/20170228214007.5621-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.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>
NR_PAGES_SCANNED counts number of pages scanned since the last page free
event in the allocator. This was used primarily to measure the
reclaimability of zones and nodes, and determine when reclaim should
give up on them. In that role, it has been replaced in the preceding
patches by a different mechanism.
Being implemented as an efficient vmstat counter, it was automatically
exported to userspace as well. It's however unlikely that anyone
outside the kernel is using this counter in any meaningful way.
Remove the counter and the unused pgdat_reclaimable().
Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.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>
Patch series "mm: kswapd spinning on unreclaimable nodes - fixes and
cleanups".
Jia reported a scenario in which the kswapd of a node indefinitely spins
at 100% CPU usage. We have seen similar cases at Facebook.
The kernel's current method of judging its ability to reclaim a node (or
whether to back off and sleep) is based on the amount of scanned pages
in proportion to the amount of reclaimable pages. In Jia's and our
scenarios, there are no reclaimable pages in the node, however, and the
condition for backing off is never met. Kswapd busyloops in an attempt
to restore the watermarks while having nothing to work with.
This series reworks the definition of an unreclaimable node based not on
scanning but on whether kswapd is able to actually reclaim pages in
MAX_RECLAIM_RETRIES (16) consecutive runs. This is the same criteria
the page allocator uses for giving up on direct reclaim and invoking the
OOM killer. If it cannot free any pages, kswapd will go to sleep and
leave further attempts to direct reclaim invocations, which will either
make progress and re-enable kswapd, or invoke the OOM killer.
Patch #1 fixes the immediate problem Jia reported, the remainder are
smaller fixlets, cleanups, and overall phasing out of the old method.
Patch #6 is the odd one out. It's a nice cleanup to get_scan_count(),
and directly related to #5, but in itself not relevant to the series.
If the whole series is too ambitious for 4.11, I would consider the
first three patches fixes, the rest cleanups.
This patch (of 9):
Jia He reports a problem with kswapd spinning at 100% CPU when
requesting more hugepages than memory available in the system:
$ echo 4000 >/proc/sys/vm/nr_hugepages
top - 13:42:59 up 3:37, 1 user, load average: 1.09, 1.03, 1.01
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 12.5 sy, 0.0 ni, 85.5 id, 2.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 31371520 total, 30915136 used, 456384 free, 320 buffers
KiB Swap: 6284224 total, 115712 used, 6168512 free. 48192 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
76 root 20 0 0 0 0 R 100.0 0.000 217:17.29 kswapd3
At that time, there are no reclaimable pages left in the node, but as
kswapd fails to restore the high watermarks it refuses to go to sleep.
Kswapd needs to back away from nodes that fail to balance. Up until
commit 1d82de618d ("mm, vmscan: make kswapd reclaim in terms of
nodes") kswapd had such a mechanism. It considered zones whose
theoretically reclaimable pages it had reclaimed six times over as
unreclaimable and backed away from them. This guard was erroneously
removed as the patch changed the definition of a balanced node.
However, simply restoring this code wouldn't help in the case reported
here: there *are* no reclaimable pages that could be scanned until the
threshold is met. Kswapd would stay awake anyway.
Introduce a new and much simpler way of backing off. If kswapd runs
through MAX_RECLAIM_RETRIES (16) cycles without reclaiming a single
page, make it back off from the node. This is the same number of shots
direct reclaim takes before declaring OOM. Kswapd will go to sleep on
that node until a direct reclaimer manages to reclaim some pages, thus
proving the node reclaimable again.
[hannes@cmpxchg.org: check kswapd failure against the cumulative nr_reclaimed count]
Link: http://lkml.kernel.org/r/20170306162410.GB2090@cmpxchg.org
[shakeelb@google.com: fix condition for throttle_direct_reclaim]
Link: http://lkml.kernel.org/r/20170314183228.20152-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20170228214007.5621-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Jia He <hejianet@gmail.com>
Tested-by: Jia He <hejianet@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
guide for user-space API documents, rather sparsely populated at the
moment, but it's a start. Markus improved the infrastructure for
converting diagrams. Mauro has converted much of the USB documentation
over to RST. Plus the usual set of fixes, improvements, and tweaks.
There's a bit more than the usual amount of reaching out of Documentation/
to fix comments elsewhere in the tree; I have acks for those where I could
get them.
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Merge tag 'docs-4.12' of git://git.lwn.net/linux
Pull documentation update from Jonathan Corbet:
"A reasonably busy cycle for documentation this time around. There is a
new guide for user-space API documents, rather sparsely populated at
the moment, but it's a start. Markus improved the infrastructure for
converting diagrams. Mauro has converted much of the USB documentation
over to RST. Plus the usual set of fixes, improvements, and tweaks.
There's a bit more than the usual amount of reaching out of
Documentation/ to fix comments elsewhere in the tree; I have acks for
those where I could get them"
* tag 'docs-4.12' of git://git.lwn.net/linux: (74 commits)
docs: Fix a couple typos
docs: Fix a spelling error in vfio-mediated-device.txt
docs: Fix a spelling error in ioctl-number.txt
MAINTAINERS: update file entry for HSI subsystem
Documentation: allow installing man pages to a user defined directory
Doc/PM: Sync with intel_powerclamp code behavior
zr364xx.rst: usb/devices is now at /sys/kernel/debug/
usb.rst: move documentation from proc_usb_info.txt to USB ReST book
convert philips.txt to ReST and add to media docs
docs-rst: usb: update old usbfs-related documentation
arm: Documentation: update a path name
docs: process/4.Coding.rst: Fix a couple of document refs
docs-rst: fix usb cross-references
usb: gadget.h: be consistent at kernel doc macros
usb: composite.h: fix two warnings when building docs
usb: get rid of some ReST doc build errors
usb.rst: get rid of some Sphinx errors
usb/URB.txt: convert to ReST and update it
usb/persist.txt: convert to ReST and add to driver-api book
usb/hotplug.txt: convert to ReST and add to driver-api book
...
This reverts commit 374ad05ab6.
While the patch worked great for userspace allocations, the fact that
softirq loses the per-cpu allocator caused problems. It needs to be
redone taking into account that a separate list is needed for hard/soft
IRQs or alternatively find a cheap way of detecting reentry due to an
interrupt. Both are possible but sufficiently tricky that it shouldn't
be rushed.
Jesper had one method for allowing softirqs but reported that the cost
was high enough that it performed similarly to a plain revert. His
figures for netperf TCP_STREAM were as follows
Baseline v4.10.0 : 60316 Mbit/s
Current 4.11.0-rc6: 47491 Mbit/s
Jesper's patch : 60662 Mbit/s
This patch : 60106 Mbit/s
As this is a regression, I wish to revert to noirq allocator for now and
go back to the drawing board.
Link: http://lkml.kernel.org/r/20170415145350.ixy7vtrzdzve57mh@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Tariq Toukan <ttoukan.linux@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently have 2 specific WQ_RECLAIM workqueues in the mm code.
vmstat_wq for updating pcp stats and lru_add_drain_wq dedicated to drain
per cpu lru caches. This seems more than necessary because both can run
on a single WQ. Both do not block on locks requiring a memory
allocation nor perform any allocations themselves. We will save one
rescuer thread this way.
On the other hand drain_all_pages() queues work on the system wq which
doesn't have rescuer and so this depend on memory allocation (when all
workers are stuck allocating and new ones cannot be created).
Initially we thought this would be more of a theoretical problem but
Hugh Dickins has reported:
: 4.11-rc has been giving me hangs after hours of swapping load. At
: first they looked like memory leaks ("fork: Cannot allocate memory");
: but for no good reason I happened to do "cat /proc/sys/vm/stat_refresh"
: before looking at /proc/meminfo one time, and the stat_refresh stuck
: in D state, waiting for completion of flush_work like many kworkers.
: kthreadd waiting for completion of flush_work in drain_all_pages().
This worker should be using WQ_RECLAIM as well in order to guarantee a
forward progress. We can reuse the same one as for lru draining and
vmstat.
Link: http://lkml.kernel.org/r/20170307131751.24936-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Yang Li <pku.leo@gmail.com>
Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Relying on free_reserved_area() to call ftrace to free init memory proved to
not be sufficient. The issue is that on x86, when debug_pagealloc is
enabled, the init memory is not freed, but simply set as not present. Since
ftrace was uninformed of this, starting function tracing still tries to
update pages that are not present according to the page tables, causing
ftrace to bug, as well as killing the kernel itself.
Instead of relying on free_reserved_area(), have init/main.c call ftrace
directly just before it frees the init memory. Then it needs to use
__init_begin and __init_end to know where the init memory location is.
Looking at all archs (and testing what I can), it appears that this should
work for each of them.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Adding a hook into free_reserve_area() that informs ftrace that boot up init
text is being free, lets ftrace safely remove those init functions from its
records, which keeps ftrace from trying to modify text that no longer
exists.
Note, this still does not allow for tracing .init text of modules, as
modules require different work for freeing its init code.
Link: http://lkml.kernel.org/r/1488502497.7212.24.camel@linux.intel.com
Cc: linux-mm@kvack.org
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Requested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Commit 13ad59df67 ("mm, page_alloc: avoid page_to_pfn() when merging
buddies") moved the check for memory holes out of page_is_buddy() and
had the callers do the check.
But this wasn't done correctly in one place which caused ia64 to crash
very early in boot.
Update to fix that and make ia64 boot again.
[ v2: Vlastimil pointed out we don't need to call page_to_pfn()
since we already have the result of that in "buddy_pfn" ]
Fixes: 13ad59df67 ("avoid page_to_pfn() when merging buddies")
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Update the .c files that depend on these APIs.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix typos and add the following to the scripts/spelling.txt:
algined||aligned
While we are here, fix the "appplication" in the touched line in
drivers/block/loop.c. Also, fix the "may not naturally ..." to
"may not be naturally ..." in the touched line in mm/page_alloc.
Link: http://lkml.kernel.org/r/1481573103-11329-9-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch_zone_lowest/highest_possible_pfn[] is set to 0 and [ZONE_MOVABLE]
is skipped in the loop. No need to reset them to 0 again.
This patch just removes the redundant code.
Link: http://lkml.kernel.org/r/20170209141731.60208-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When @node_reclaim_node isn't 0, the page allocator tries to reclaim
pages if the amount of free memory in the zones are below the low
watermark. On Power platform, none of NUMA nodes are scanned for page
reclaim because no nodes match the condition in zone_allows_reclaim().
On Power platform, RECLAIM_DISTANCE is set to 10 which is the distance
of Node-A to Node-A. So the preferred node even won't be scanned for
page reclaim.
__alloc_pages_nodemask()
get_page_from_freelist()
zone_allows_reclaim()
Anton proposed the test code as below:
# cat alloc.c
:
int main(int argc, char *argv[])
{
void *p;
unsigned long size;
unsigned long start, end;
start = time(NULL);
size = strtoul(argv[1], NULL, 0);
printf("To allocate %ldGB memory\n", size);
size <<= 30;
p = malloc(size);
assert(p);
memset(p, 0, size);
end = time(NULL);
printf("Used time: %ld seconds\n", end - start);
sleep(3600);
return 0;
}
The system I use for testing has two NUMA nodes. Both have 128GB
memory. In below scnario, the page caches on node#0 should be reclaimed
when it encounters pressure to accommodate request of allocation.
# echo 2 > /proc/sys/vm/zone_reclaim_mode; \
sync; \
echo 3 > /proc/sys/vm/drop_caches; \
# taskset -c 0 cat file.32G > /dev/null; \
grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33619712 kB
# taskset -c 0 ./alloc 128
# grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33619840 kB
# grep MemFree /sys/devices/system/node/node0/meminfo
Node 0 MemFree: 186816 kB
With the patch applied, the pagecache on node-0 is reclaimed when its
free memory is running out. It's the expected behaviour.
# echo 2 > /proc/sys/vm/zone_reclaim_mode; \
sync; \
echo 3 > /proc/sys/vm/drop_caches
# taskset -c 0 cat file.32G > /dev/null; \
grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33605568 kB
# taskset -c 0 ./alloc 128
# grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 1379520 kB
# grep MemFree /sys/devices/system/node/node0/meminfo
Node 0 MemFree: 317120 kB
Fixes: 5f7a75acdb ("mm: page_alloc: do not cache reclaim distances")
Link: http://lkml.kernel.org/r/1486532455-29613-1-git-send-email-gwshan@linux.vnet.ibm.com
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org> [3.16+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently alloc_contig_range assumes that the compaction should be done
with the default GFP_KERNEL flags. This is probably right for all
current uses of this interface, but may change as CMA is used in more
use-cases (including being the default DMA memory allocator on some
platforms).
Change the function prototype, to allow for passing through the GFP mask
set by upper layers.
Also respect global restrictions by applying memalloc_noio_flags to the
passed in flags.
Link: http://lkml.kernel.org/r/20170127172328.18574-1-l.stach@pengutronix.de
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexander Graf <agraf@suse.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>
We had considered all of the non-lru pages as unmovable before commit
bda807d444 ("mm: migrate: support non-lru movable page migration").
But now some of non-lru pages like zsmalloc, virtio-balloon pages also
become movable. So we can offline such blocks by using non-lru page
migration.
This patch straightforwardly adds non-lru migration code, which means
adding non-lru related code to the functions which scan over pfn and
collect pages to be migrated and isolate them before migration.
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As suggested by Vlastimil Babka and Tejun Heo, this patch uses a static
work_struct to co-ordinate the draining of per-cpu pages on the
workqueue. Only one task can drain at a time but this is better than
the previous scheme that allowed multiple tasks to send IPIs at a time.
One consideration is whether parallel requests should synchronise
against each other. This patch does not synchronise for a global drain
as the common case for such callers is expected to be multiple parallel
direct reclaimers competing for pages when the watermark is close to
min. Draining the per-cpu list is unlikely to make much progress and
serialising the drain is of dubious merit. Drains are synchonrised for
callers such as memory hotplug and CMA that care about the drain being
complete when the function returns.
Link: http://lkml.kernel.org/r/20170125083038.rzb5f43nptmk7aed@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Suggested-by: Tejun Heo <tj@kernel.org>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 682a3385e7 ("mm, page_alloc: inline the fast path of the
zonelist iterator") we replace a NULL nodemask with
cpuset_current_mems_allowed in the fast path, so that
get_page_from_freelist() filters nodes allowed by the cpuset via
for_next_zone_zonelist_nodemask().
In that case it's pointless to additionaly check __cpuset_zone_allowed()
in each iteration, which we can avoid by not adding ALLOC_CPUSET to
alloc_flags in that scenario.
This saves some cycles in the allocator fast path on systems with one or
more non-root cpuset configured. In the slow path, ALLOC_CPUSET is
reset according to __alloc_pages_slowpath(). Without configured
cpusets, this code is disabled by a static key.
Link: http://lkml.kernel.org/r/20170124150511.5710-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.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>
The allocation fast path contains two similar checks for zoneref->zone
being NULL, where zoneref points either to the first zone in the
zonelist, or to the preferred zone. These can be NULL either due to
empty zonelist, or no zone being compatible with given nodemask or
task's cpuset.
These checks are unnecessary, because the zonelist walks in
first_zones_zonelist() and get_page_from_freelist() handle a NULL
starting zoneref->zone or preferred_zoneref->zone safely. It's safe to
fallback to __alloc_pages_slowpath() where we also have the check early
enough.
Link: http://lkml.kernel.org/r/20170124150511.5710-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.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>
Many workloads that allocate pages are not handling an interrupt at a
time. As allocation requests may be from IRQ context, it's necessary to
disable/enable IRQs for every page allocation. This cost is the bulk of
the free path but also a significant percentage of the allocation path.
This patch alters the locking and checks such that only irq-safe
allocation requests use the per-cpu allocator. All others acquire the
irq-safe zone->lock and allocate from the buddy allocator. It relies on
disabling preemption to safely access the per-cpu structures. It could
be slightly modified to avoid soft IRQs using it but it's not clear it's
worthwhile.
This modification may slow allocations from IRQ context slightly but the
main gain from the per-cpu allocator is that it scales better for
allocations from multiple contexts. There is an implicit assumption
that intensive allocations from IRQ contexts on multiple CPUs from a
single NUMA node are rare and that the fast majority of scaling issues
are encountered in !IRQ contexts such as page faulting. It's worth
noting that this patch is not required for a bulk page allocator but it
significantly reduces the overhead.
The following is results from a page allocator micro-benchmark. Only
order-0 is interesting as higher orders do not use the per-cpu allocator
4.10.0-rc2 4.10.0-rc2
vanilla irqsafe-v1r5
Amean alloc-odr0-1 287.15 ( 0.00%) 219.00 ( 23.73%)
Amean alloc-odr0-2 221.23 ( 0.00%) 183.23 ( 17.18%)
Amean alloc-odr0-4 187.00 ( 0.00%) 151.38 ( 19.05%)
Amean alloc-odr0-8 167.54 ( 0.00%) 132.77 ( 20.75%)
Amean alloc-odr0-16 156.00 ( 0.00%) 123.00 ( 21.15%)
Amean alloc-odr0-32 149.00 ( 0.00%) 118.31 ( 20.60%)
Amean alloc-odr0-64 138.77 ( 0.00%) 116.00 ( 16.41%)
Amean alloc-odr0-128 145.00 ( 0.00%) 118.00 ( 18.62%)
Amean alloc-odr0-256 136.15 ( 0.00%) 125.00 ( 8.19%)
Amean alloc-odr0-512 147.92 ( 0.00%) 121.77 ( 17.68%)
Amean alloc-odr0-1024 147.23 ( 0.00%) 126.15 ( 14.32%)
Amean alloc-odr0-2048 155.15 ( 0.00%) 129.92 ( 16.26%)
Amean alloc-odr0-4096 164.00 ( 0.00%) 136.77 ( 16.60%)
Amean alloc-odr0-8192 166.92 ( 0.00%) 138.08 ( 17.28%)
Amean alloc-odr0-16384 159.00 ( 0.00%) 138.00 ( 13.21%)
Amean free-odr0-1 165.00 ( 0.00%) 89.00 ( 46.06%)
Amean free-odr0-2 113.00 ( 0.00%) 63.00 ( 44.25%)
Amean free-odr0-4 99.00 ( 0.00%) 54.00 ( 45.45%)
Amean free-odr0-8 88.00 ( 0.00%) 47.38 ( 46.15%)
Amean free-odr0-16 83.00 ( 0.00%) 46.00 ( 44.58%)
Amean free-odr0-32 80.00 ( 0.00%) 44.38 ( 44.52%)
Amean free-odr0-64 72.62 ( 0.00%) 43.00 ( 40.78%)
Amean free-odr0-128 78.00 ( 0.00%) 42.00 ( 46.15%)
Amean free-odr0-256 80.46 ( 0.00%) 57.00 ( 29.16%)
Amean free-odr0-512 96.38 ( 0.00%) 64.69 ( 32.88%)
Amean free-odr0-1024 107.31 ( 0.00%) 72.54 ( 32.40%)
Amean free-odr0-2048 108.92 ( 0.00%) 78.08 ( 28.32%)
Amean free-odr0-4096 113.38 ( 0.00%) 82.23 ( 27.48%)
Amean free-odr0-8192 112.08 ( 0.00%) 82.85 ( 26.08%)
Amean free-odr0-16384 110.38 ( 0.00%) 81.92 ( 25.78%)
Amean total-odr0-1 452.15 ( 0.00%) 308.00 ( 31.88%)
Amean total-odr0-2 334.23 ( 0.00%) 246.23 ( 26.33%)
Amean total-odr0-4 286.00 ( 0.00%) 205.38 ( 28.19%)
Amean total-odr0-8 255.54 ( 0.00%) 180.15 ( 29.50%)
Amean total-odr0-16 239.00 ( 0.00%) 169.00 ( 29.29%)
Amean total-odr0-32 229.00 ( 0.00%) 162.69 ( 28.96%)
Amean total-odr0-64 211.38 ( 0.00%) 159.00 ( 24.78%)
Amean total-odr0-128 223.00 ( 0.00%) 160.00 ( 28.25%)
Amean total-odr0-256 216.62 ( 0.00%) 182.00 ( 15.98%)
Amean total-odr0-512 244.31 ( 0.00%) 186.46 ( 23.68%)
Amean total-odr0-1024 254.54 ( 0.00%) 198.69 ( 21.94%)
Amean total-odr0-2048 264.08 ( 0.00%) 208.00 ( 21.24%)
Amean total-odr0-4096 277.38 ( 0.00%) 219.00 ( 21.05%)
Amean total-odr0-8192 279.00 ( 0.00%) 220.92 ( 20.82%)
Amean total-odr0-16384 269.38 ( 0.00%) 219.92 ( 18.36%)
This is the alloc, free and total overhead of allocating order-0 pages
in batches of 1 page up to 16384 pages. Avoiding disabling/enabling
overhead massively reduces overhead. Alloc overhead is roughly reduced
by 14-20% in most cases. The free path is reduced by 26-46% and the
total reduction is significant.
Many users require zeroing of pages from the page allocator which is the
vast cost of allocation. Hence, the impact on a basic page faulting
benchmark is not that significant
4.10.0-rc2 4.10.0-rc2
vanilla irqsafe-v1r5
Hmean page_test 656632.98 ( 0.00%) 675536.13 ( 2.88%)
Hmean brk_test 3845502.67 ( 0.00%) 3867186.94 ( 0.56%)
Stddev page_test 10543.29 ( 0.00%) 4104.07 ( 61.07%)
Stddev brk_test 33472.36 ( 0.00%) 15538.39 ( 53.58%)
CoeffVar page_test 1.61 ( 0.00%) 0.61 ( 62.15%)
CoeffVar brk_test 0.87 ( 0.00%) 0.40 ( 53.84%)
Max page_test 666513.33 ( 0.00%) 678640.00 ( 1.82%)
Max brk_test 3882800.00 ( 0.00%) 3887008.66 ( 0.11%)
This is from aim9 and the most notable outcome is that fault variability
is reduced by the patch. The headline improvement is small as the
overall fault cost, zeroing, page table insertion etc dominate relative
to disabling/enabling IRQs in the per-cpu allocator.
Similarly, little benefit was seen on networking benchmarks both
localhost and between physical server/clients where other costs
dominate. It's possible that this will only be noticable on very high
speed networks.
Jesper Dangaard Brouer independently tested this with a separate
microbenchmark from
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench
Micro-benchmarked with [1] page_bench02:
modprobe page_bench02 page_order=0 run_flags=$((2#010)) loops=$((10**8)); \
rmmod page_bench02 ; dmesg --notime | tail -n 4
Compared to baseline: 213 cycles(tsc) 53.417 ns
- against this : 184 cycles(tsc) 46.056 ns
- Saving : -29 cycles
- Very close to expected 27 cycles saving [see below [2]]
Micro benchmarking via time_bench_sample[3], we get the cost of these
operations:
time_bench: Type:for_loop Per elem: 0 cycles(tsc) 0.232 ns (step:0)
time_bench: Type:spin_lock_unlock Per elem: 33 cycles(tsc) 8.334 ns (step:0)
time_bench: Type:spin_lock_unlock_irqsave Per elem: 62 cycles(tsc) 15.607 ns (step:0)
time_bench: Type:irqsave_before_lock Per elem: 57 cycles(tsc) 14.344 ns (step:0)
time_bench: Type:spin_lock_unlock_irq Per elem: 34 cycles(tsc) 8.560 ns (step:0)
time_bench: Type:simple_irq_disable_before_lock Per elem: 37 cycles(tsc) 9.289 ns (step:0)
time_bench: Type:local_BH_disable_enable Per elem: 19 cycles(tsc) 4.920 ns (step:0)
time_bench: Type:local_IRQ_disable_enable Per elem: 7 cycles(tsc) 1.864 ns (step:0)
time_bench: Type:local_irq_save_restore Per elem: 38 cycles(tsc) 9.665 ns (step:0)
[Mel's patch removes a ^^^^^^^^^^^^^^^^] ^^^^^^^^^ expected saving - preempt cost
time_bench: Type:preempt_disable_enable Per elem: 11 cycles(tsc) 2.794 ns (step:0)
[adds a preempt ^^^^^^^^^^^^^^^^^^^^^^] ^^^^^^^^^ adds this cost
time_bench: Type:funcion_call_cost Per elem: 6 cycles(tsc) 1.689 ns (step:0)
time_bench: Type:func_ptr_call_cost Per elem: 11 cycles(tsc) 2.767 ns (step:0)
time_bench: Type:page_alloc_put Per elem: 211 cycles(tsc) 52.803 ns (step:0)
Thus, expected improvement is: 38-11 = 27 cycles.
[mgorman@techsingularity.net: s/preempt_enable_no_resched/preempt_enable/]
Link: http://lkml.kernel.org/r/20170208143128.25ahymqlyspjcixu@techsingularity.net
Link: http://lkml.kernel.org/r/20170123153906.3122-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Dmitry has reported the following lockdep splat
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3753
__mutex_lock_common kernel/locking/mutex.c:521 [inline]
mutex_lock_nested+0x24e/0xff0 kernel/locking/mutex.c:621
pcpu_alloc+0xbda/0x1280 mm/percpu.c:896
__alloc_percpu+0x24/0x30 mm/percpu.c:1075
smpcfd_prepare_cpu+0x73/0xd0 kernel/smp.c:44
cpuhp_invoke_callback+0x254/0x1480 kernel/cpu.c:136
cpuhp_up_callbacks+0x81/0x2a0 kernel/cpu.c:493
_cpu_up+0x1e3/0x2a0 kernel/cpu.c:1057
do_cpu_up+0x73/0xa0 kernel/cpu.c:1087
cpu_up+0x18/0x20 kernel/cpu.c:1095
smp_init+0xe9/0xee kernel/smp.c:564
kernel_init_freeable+0x439/0x690 init/main.c:1010
kernel_init+0x13/0x180 init/main.c:941
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
cpu_hotplug_begin
cpu_hotplug.lock
pcpu_alloc
pcpu_alloc_mutex
get_online_cpus+0x62/0x90 kernel/cpu.c:248
drain_all_pages+0xf8/0x710 mm/page_alloc.c:2385
__alloc_pages_direct_reclaim mm/page_alloc.c:3440 [inline]
__alloc_pages_slowpath+0x8fd/0x2370 mm/page_alloc.c:3778
__alloc_pages_nodemask+0x8f5/0xc60 mm/page_alloc.c:3980
__alloc_pages include/linux/gfp.h:426 [inline]
__alloc_pages_node include/linux/gfp.h:439 [inline]
alloc_pages_node include/linux/gfp.h:453 [inline]
pcpu_alloc_pages mm/percpu-vm.c:93 [inline]
pcpu_populate_chunk+0x1e1/0x900 mm/percpu-vm.c:282
pcpu_alloc+0xe01/0x1280 mm/percpu.c:998
__alloc_percpu_gfp+0x27/0x30 mm/percpu.c:1062
bpf_array_alloc_percpu kernel/bpf/arraymap.c:34 [inline]
array_map_alloc+0x532/0x710 kernel/bpf/arraymap.c:99
find_and_alloc_map kernel/bpf/syscall.c:34 [inline]
map_create kernel/bpf/syscall.c:188 [inline]
SYSC_bpf kernel/bpf/syscall.c:870 [inline]
SyS_bpf+0xd64/0x2500 kernel/bpf/syscall.c:827
entry_SYSCALL_64_fastpath+0x1f/0xc2
pcpu_alloc
pcpu_alloc_mutex
drain_all_pages
get_online_cpus
cpu_hotplug.lock
cpu_hotplug_begin+0x206/0x2e0 kernel/cpu.c:304
_cpu_up+0xca/0x2a0 kernel/cpu.c:1011
do_cpu_up+0x73/0xa0 kernel/cpu.c:1087
cpu_up+0x18/0x20 kernel/cpu.c:1095
smp_init+0xe9/0xee kernel/smp.c:564
kernel_init_freeable+0x439/0x690 init/main.c:1010
kernel_init+0x13/0x180 init/main.c:941
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
cpu_hotplug_begin
cpu_hotplug.lock
Pulling cpu hotplug locks inside the page allocator is just too
dangerous. Let's remove the dependency by dropping get_online_cpus()
from drain_all_pages. This is not so simple though because now we do
not have a protection against cpu hotplug which means 2 things:
- the work item might be executed on a different cpu in worker from
unbound pool so it doesn't run on pinned on the cpu
- we have to make sure that we do not race with page_alloc_cpu_dead
calling drain_pages_zone
Disabling preemption in drain_local_pages_wq will solve the first
problem drain_local_pages will determine its local CPU from the WQ
context which will be stable after that point, page_alloc_cpu_dead is
pinned to the CPU already. The later condition is achieved by disabling
IRQs in drain_pages_zone.
Fixes: mm, page_alloc: drain per-cpu pages from workqueue context
Link: http://lkml.kernel.org/r/20170207201950.20482-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The per-cpu page allocator can be drained immediately via
drain_all_pages() which sends IPIs to every CPU. In the next patch, the
per-cpu allocator will only be used for interrupt-safe allocations which
prevents draining it from IPI context. This patch uses workqueues to
drain the per-cpu lists instead.
This is slower but no slowdown during intensive reclaim was measured and
the paths that use drain_all_pages() are not that sensitive to
performance. This is particularly true as the path would only be
triggered when reclaim is failing. It also makes a some sense to avoid
storming a machine with IPIs when it's under memory pressure. Arguably,
it should be further adjusted so that only one caller at a time is
draining pages but it's beyond the scope of the current patch.
Link: http://lkml.kernel.org/r/20170123153906.3122-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
alloc_pages_nodemask does a number of preperation steps that determine
what zones can be used for the allocation depending on a variety of
factors. This is fine but a hypothetical caller that wanted multiple
order-0 pages has to do the preparation steps multiple times. This
patch structures __alloc_pages_nodemask such that it's relatively easy
to build a bulk order-0 page allocator. There is no functional change.
Link: http://lkml.kernel.org/r/20170123153906.3122-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Use per-cpu allocator for !irq requests and prepare for a
bulk allocator", v5.
This series is motivated by a conversation led by Jesper Dangaard Brouer
at the last LSF/MM proposing a generic page pool for DMA-coherent pages.
Part of his motivation was due to the overhead of allocating multiple
order-0 that led some drivers to use high-order allocations and
splitting them. This is very slow in some cases.
The first two patches in this series restructure the page allocator such
that it is relatively easy to introduce an order-0 bulk page allocator.
A patch exists to do that and has been handed over to Jesper until an
in-kernel users is created. The third patch prevents the per-cpu
allocator being drained from IPI context as that can potentially corrupt
the list after patch four is merged. The final patch alters the per-cpu
alloctor to make it exclusive to !irq requests. This cuts
allocation/free overhead by roughly 30%.
Performance tests from both Jesper and me are included in the patch.
This patch (of 4):
buffered_rmqueue removes a page from a given zone and uses the per-cpu
list for order-0. This is fine but a hypothetical caller that wanted
multiple order-0 pages has to disable/reenable interrupts multiple
times. This patch structures buffere_rmqueue such that it's relatively
easy to build a bulk order-0 page allocator. There is no functional
change.
[mgorman@techsingularity.net: failed per-cpu refill may blow up]
Link: http://lkml.kernel.org/r/20170124112723.mshmgwq2ihxku2um@techsingularity.net
Link: http://lkml.kernel.org/r/20170123153906.3122-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets
the allocation nodemask to cpuset_current_mems_allowed when there is no
effective mempolicy. cpuset_current_mems_allowed is only effective when
cpusets are enabled, which is also printed by warn_alloc(), so setting
the nodemask to cpuset_current_mems_allowed is redundant and prevents
debugging issues where ac->nodemask is not set properly in the page
allocator.
This provides better debugging output since
cpuset_print_current_mems_allowed() is already provided.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701181347320.142399@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that __GFP_NOFAIL doesn't override decisions to skip the oom killer
we are left with requests which require to loop inside the allocator
without invoking the oom killer (e.g. GFP_NOFS|__GFP_NOFAIL used by fs
code) and so they might, in very unlikely situations, loop for ever -
e.g. other parallel request could starve them.
This patch tries to limit the likelihood of such a lockup by giving
these __GFP_NOFAIL requests a chance to move on by consuming a small
part of memory reserves. We are using ALLOC_HARDER which should be
enough to prevent from the starvation by regular allocation requests,
yet it shouldn't consume enough from the reserves to disrupt high
priority requests (ALLOC_HIGH).
While we are at it, let's introduce a helper __alloc_pages_cpuset_fallback
which enforces the cpusets but allows to fallback to ignore them if the
first attempt fails. __GFP_NOFAIL requests can be considered important
enough to allow cpuset runaway in order for the system to move on. It
is highly unlikely that any of these will be GFP_USER anyway.
Link: http://lkml.kernel.org/r/20161220134904.21023-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__alloc_pages_may_oom makes sure to skip the OOM killer depending on the
allocation request. This includes lowmem requests, costly high order
requests and others. For a long time __GFP_NOFAIL acted as an override
for all those rules. This is not documented and it can be quite
surprising as well. E.g. GFP_NOFS requests are not invoking the OOM
killer but GFP_NOFS|__GFP_NOFAIL does so if we try to convert some of
the existing open coded loops around allocator to nofail request (and we
have done that in the past) then such a change would have a non trivial
side effect which is far from obvious. Note that the primary motivation
for skipping the OOM killer is to prevent from pre-mature invocation.
The exception has been added by commit 82553a937f ("oom: invoke oom
killer for __GFP_NOFAIL"). The changelog points out that the oom killer
has to be invoked otherwise the request would be looping for ever. But
this argument is rather weak because the OOM killer doesn't really
guarantee a forward progress for those exceptional cases:
- it will hardly help to form costly order which in turn can result in
the system panic because of no oom killable task in the end - I believe
we certainly do not want to put the system down just because there is a
nasty driver asking for order-9 page with GFP_NOFAIL not realizing all
the consequences. It is much better this request would loop for ever
than the massive system disruption
- lowmem is also highly unlikely to be freed during OOM killer
- GFP_NOFS request could trigger while there is still a lot of memory
pinned by filesystems.
This patch simply removes the __GFP_NOFAIL special case in order to have a
more clear semantic without surprising side effects.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Nils Holland <nholland@tisys.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tetsuo Handa has pointed out that commit 0a0337e0d1 ("mm, oom: rework
oom detection") has subtly changed semantic for costly high order
requests with __GFP_NOFAIL and withtout __GFP_REPEAT and those can fail
right now. My code inspection didn't reveal any such users in the tree
but it is true that this might lead to unexpected allocation failures
and subsequent OOPs.
__alloc_pages_slowpath wrt. GFP_NOFAIL is hard to follow currently.
There are few special cases but we are lacking a catch all place to be
sure we will not miss any case where the non failing allocation might
fail. This patch reorganizes the code a bit and puts all those special
cases under nopage label which is the generic go-to-fail path. Non
failing allocations are retried or those that cannot retry like
non-sleeping allocation go to the failure point directly. This should
make the code flow much easier to follow and make it less error prone
for future changes.
While we are there we have to move the stall check up to catch
potentially looping non-failing allocations.
[akpm@linux-foundation.org: fix alloc_flags may-be-used-uninitalized]
Link: http://lkml.kernel.org/r/20161220134904.21023-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
show_mem() allows to filter out node specific data which is irrelevant
to the allocation request via SHOW_MEM_FILTER_NODES. The filtering is
done in skip_free_areas_node which skips all nodes which are not in the
mems_allowed of the current process. This works most of the time as
expected because the nodemask shouldn't be outside of the allocating
task but there are some exceptions. E.g. memory hotplug might want to
request allocations from outside of the allowed nodes (see
new_node_page).
Get rid of this hardcoded behavior and push the allocation mask down the
show_mem path and use it instead of cpuset_current_mems_allowed. NULL
nodemask is interpreted as cpuset_current_mems_allowed.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170117091543.25850-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
warn_alloc is currently used for to report an allocation failure or an
allocation stall. We print some details of the allocation request like
the gfp mask and the request order. We do not print the allocation
nodemask which is important when debugging the reason for the allocation
failure as well. We alreaddy print the nodemask in the OOM report.
Add nodemask to warn_alloc and print it in warn_alloc as well.
Link: http://lkml.kernel.org/r/20170117091543.25850-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "show_mem updates", v2.
This is a mixture of one bug fix (patch 1), an enhancement (patch 2) and
cleanups (the rest of the series). First two patches should be really
straightforward. Patch 3 removes some arch specific show_mem
implementations because I think they are quite outdated and do not
really serve any useful purpose anymore. I think we should really
strive to have a consistent show_mem output regardless of the
architecture. If some architecture is really special and wants to dump
something additional we should do that via an arch specific hook.
The last patch adds nodemask parameter so that we do not rely on the
hardcoded mems_allowed of the current task when doing the node
filtering. I consider this more a cleanup than a fix because basically
all users use a nodemask which is a subset of mems_allowed. There is
only one call path in the memory hotplug which doesn't comply with this
but that is hardly something to worry about.
This patch (of 4):
Commit 599d0c954f ("mm, vmscan: move LRU lists to node") has added per
numa node statistics to show_mem but it forgot to add
skip_free_areas_node to filter out nodes which are outside of the
allocating task numa policy. Add this check to not pollute the output
with the pointless information.
Link: http://lkml.kernel.org/r/20170117091543.25850-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: David Rientjes <rientjes@google.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>
When using a sparse memory model memmap_init_zone() when invoked with
the MEMMAP_EARLY context will skip over pages which aren't valid - ie.
which aren't in a populated region of the sparse memory map. However if
the memory map is extremely sparse then it can spend a long time
linearly checking each PFN in a large non-populated region of the memory
map & skipping it in turn.
When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient
information to quickly discover the next valid PFN given an invalid one
by searching through the list of memory regions & skipping forwards to
the first PFN covered by the memory region to the right of the
non-populated region. Implement this in order to speed up
memmap_init_zone() for systems with extremely sparse memory maps.
James said "I have tested this patch on a virtual model of a Samurai CPU
with a sparse memory map. The kernel boot time drops from 109 to
62 seconds. "
Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@imgtec.com
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Tested-by: James Hartley <james.hartley@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Higher order requests oom debugging is currently quite hard. We do have
some compaction points which can tell us how the compaction is operating
but there is no trace point to tell us about compaction retry logic.
This patch adds a one which will have the following format
bash-3126 [001] .... 1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0
we can see that the order 9 request is not retried even though we are in
the highest compaction priority mode becase the last compaction attempt
was withdrawn. This means that compaction_zonelist_suitable must have
returned false and there is no suitable zone to compact for this request
and so no need to retry further.
another example would be
<...>-3137 [001] .... 81.501689: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=failed retries=0 max_retries=16 should_retry=0
in this case the order-9 compaction failed to find any suitable block.
We do not retry anymore because this is a costly request and those do
not go below COMPACT_PRIO_SYNC_LIGHT priority.
Link: http://lkml.kernel.org/r/20161220130135.15719-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.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>
should_reclaim_retry is the central decision point for declaring the
OOM. It might be really useful to expose data used for this decision
making when debugging an unexpected oom situations.
Say we have an OOM report:
[ 52.264001] mem_eater invoked oom-killer: gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=0, order=0, oom_score_adj=0
[ 52.267549] CPU: 3 PID: 3148 Comm: mem_eater Tainted: G W 4.8.0-oomtrace3-00006-gb21338b386d2 #1024
Now we can check the tracepoint data to see how we have ended up in this
situation:
mem_eater-3148 [003] .... 52.432801: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11134 min_wmark=11084 no_progress_loops=1 wmark_check=1
mem_eater-3148 [003] .... 52.433269: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11103 min_wmark=11084 no_progress_loops=1 wmark_check=1
mem_eater-3148 [003] .... 52.433712: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11100 min_wmark=11084 no_progress_loops=2 wmark_check=1
mem_eater-3148 [003] .... 52.434067: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11097 min_wmark=11084 no_progress_loops=3 wmark_check=1
mem_eater-3148 [003] .... 52.434414: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11094 min_wmark=11084 no_progress_loops=4 wmark_check=1
mem_eater-3148 [003] .... 52.434761: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11091 min_wmark=11084 no_progress_loops=5 wmark_check=1
mem_eater-3148 [003] .... 52.435108: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11087 min_wmark=11084 no_progress_loops=6 wmark_check=1
mem_eater-3148 [003] .... 52.435478: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11084 min_wmark=11084 no_progress_loops=7 wmark_check=0
mem_eater-3148 [003] .... 52.435478: reclaim_retry_zone: node=0 zone=DMA order=0 reclaimable=0 available=1126 min_wmark=179 no_progress_loops=7 wmark_check=0
The above shows that we can quickly deduce that the reclaim stopped
making any progress (see no_progress_loops increased in each round) and
while there were still some 51 reclaimable pages they couldn't be
dropped for some reason (vmscan trace points would tell us more about
that part). available will represent reclaimable + free_pages scaled
down per no_progress_loops factor. This is essentially an optimistic
estimate of how much memory we would have when reclaiming everything.
This can be compared to min_wmark to get a rought idea but the
wmark_check tells the result of the watermark check which is more
precise (includes lowmem reserves, considers the order etc.). As we can
see no zone is eligible in the end and that is why we have triggered the
oom in this situation.
Please note that higher order requests might fail on the wmark_check
even when there is much more memory available than min_wmark - e.g.
when the memory is fragmented. A follow up tracepoint will help to
debug those situations.
Link: http://lkml.kernel.org/r/20161220130135.15719-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.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>
On architectures that allow memory holes, page_is_buddy() has to perform
page_to_pfn() to check for the memory hole. After the previous patch,
we have the pfn already available in __free_one_page(), which is the
only caller of page_is_buddy(), so move the check there and avoid
page_to_pfn().
Link: http://lkml.kernel.org/r/20161216120009.20064-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
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>
In __free_one_page() we do the buddy merging arithmetics on "page/buddy
index", which is just the lower MAX_ORDER bits of pfn. The operations
we do that affect the higher bits are bitwise AND and subtraction (in
that order), where the final result will be the same with the higher
bits left unmasked, as long as these bits are equal for both buddies -
which must be true by the definition of a buddy.
We can therefore use pfn's directly instead of "index" and skip the
zeroing of >MAX_ORDER bits. This can help a bit by itself, although
compiler might be smart enough already. It also helps the next patch to
avoid page_to_pfn() for memory hole checks.
Link: http://lkml.kernel.org/r/20161216120009.20064-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
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>
Tetsuo has been stressing OOM killer path with many parallel allocation
requests when he has noticed that it is not all that hard to swamp
kernel logs with warn_alloc messages caused by allocation stalls. Even
though the allocation stall message is triggered only once in 10s there
might be many different tasks hitting it roughly around the same time.
A big part of the output is show_mem() which can generate a lot of
output even on a small machines. There is no reason to show the state
of memory counter for each allocation stall, especially when multiple of
them are reported in a short time period. Chances are that not much has
changed since the last report. This patch simply rate limits show_mem
called from warn_alloc to only dump something once per second. This
should be enough to give us a clue why an allocation might be stalling
while burst of warnings will not swamp log with too much data.
While we are at it, extract all the show_mem related handling (filters)
into a separate function warn_alloc_show_mem. This will make the code
cleaner and as a bonus point we can distinguish which part of warn_alloc
got throttled due to rate limiting as ___ratelimit dumps the caller.
[akpm@linux-foundation.org: reduce scope of the ratelimit_states]
Link: http://lkml.kernel.org/r/20161215101510.9030-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode
triggers OOM killer in few seconds, despite lots of free memory. The
test attempts to repeatedly fault in memory in one process in a cpuset,
while changing allowed nodes of the cpuset between 0 and 1 in another
process.
The problem comes from insufficient protection against cpuset changes,
which can cause get_page_from_freelist() to consider all zones as
non-eligible due to nodemask and/or current->mems_allowed. This was
masked in the past by sufficient retries, but since commit 682a3385e7
("mm, page_alloc: inline the fast path of the zonelist iterator") we fix
the preferred_zoneref once, and don't iterate over the whole zonelist in
further attempts, thus the only eligible zones might be placed in the
zonelist before our starting point and we always miss them.
A previous patch fixed this problem for current->mems_allowed. However,
cpuset changes also update the task's mempolicy nodemask. The fix has
two parts. We have to repeat the preferred_zoneref search when we
detect cpuset update by way of seqcount, and we have to check the
seqcount before considering OOM.
[akpm@linux-foundation.org: fix typo in comment]
Link: http://lkml.kernel.org/r/20170120103843.24587-5-vbabka@suse.cz
Fixes: c33d6c06f6 ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.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>
This is a preparation for the following patch to make review simpler.
While the primary motivation is a bug fix, this also simplifies the fast
path, although the moved code is only enabled when cpusets are in use.
Link: http://lkml.kernel.org/r/20170120103843.24587-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.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>
Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode
triggers OOM killer in few seconds, despite lots of free memory. The
test attempts to repeatedly fault in memory in one process in a cpuset,
while changing allowed nodes of the cpuset between 0 and 1 in another
process.
One possible cause is that in the fast path we find the preferred
zoneref according to current mems_allowed, so that it points to the
middle of the zonelist, skipping e.g. zones of node 1 completely. If
the mems_allowed is updated to contain only node 1, we never reach it in
the zonelist, and trigger OOM before checking the cpuset_mems_cookie.
This patch fixes the particular case by redoing the preferred zoneref
search if we switch back to the original nodemask. The condition is
also slightly changed so that when the last non-root cpuset is removed,
we don't miss it.
Note that this is not a full fix, and more patches will follow.
Link: http://lkml.kernel.org/r/20170120103843.24587-3-vbabka@suse.cz
Fixes: 682a3385e7 ("mm, page_alloc: inline the fast path of the zonelist iterator")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.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 "fix premature OOM regression in 4.7+ due to cpuset races".
This is v2 of my attempt to fix the recent report based on LTP cpuset
stress test [1]. The intention is to go to stable 4.9 LTSS with this,
as triggering repeated OOMs is not nice. That's why the patches try to
be not too intrusive.
Unfortunately why investigating I found that modifying the testcase to
use per-VMA policies instead of per-task policies will bring the OOM's
back, but that seems to be much older and harder to fix problem. I have
posted a RFC [2] but I believe that fixing the recent regressions has a
higher priority.
Longer-term we might try to think how to fix the cpuset mess in a better
and less error prone way. I was for example very surprised to learn,
that cpuset updates change not only task->mems_allowed, but also
nodemask of mempolicies. Until now I expected the parameter to
alloc_pages_nodemask() to be stable. I wonder why do we then treat
cpusets specially in get_page_from_freelist() and distinguish HARDWALL
etc, when there's unconditional intersection between mempolicy and
cpuset. I would expect the nodemask adjustment for saving overhead in
g_p_f(), but that clearly doesn't happen in the current form. So we
have both crazy complexity and overhead, AFAICS.
[1] https://lkml.kernel.org/r/CAFpQJXUq-JuEP=QPidy4p_=FN0rkH5Z-kfB4qBvsf6jMS87Edg@mail.gmail.com
[2] https://lkml.kernel.org/r/7c459f26-13a6-a817-e508-b65b903a8378@suse.cz
This patch (of 4):
Since commit c33d6c06f6 ("mm, page_alloc: avoid looking up the first
zone in a zonelist twice") we have a wrong check for NULL preferred_zone,
which can theoretically happen due to concurrent cpuset modification. We
check the zoneref pointer which is never NULL and we should check the zone
pointer. Also document this in first_zones_zonelist() comment per Michal
Hocko.
Fixes: c33d6c06f6 ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Link: http://lkml.kernel.org/r/20170120103843.24587-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.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>
Commit 73e64c51af ("mm, compaction: allow compaction for GFP_NOFS
requests") changed compation to skip FS pages if not explicitly allowed
to touch them, but missed to update the CMA compact_control.
This leads to a very high isolation failure rate, crippling performance
of CMA even on a lightly loaded system. Re-allow CMA to compact FS
pages by setting the correct GFP flags, restoring CMA behavior and
performance to the kernel 4.9 level.
Fixes: 73e64c51af (mm, compaction: allow compaction for GFP_NOFS requests)
Link: http://lkml.kernel.org/r/20170113115155.24335-1-l.stach@pengutronix.de
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.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 patch does two things.
First it goes through and renames the __page_frag prefixed functions to
__page_frag_cache so that we can be clear that we are draining or
refilling the cache, not the frags themselves.
Second we drop the order parameter from __page_frag_cache_drain since we
don't actually need to pass it since all fragments are either order 0 or
must be a compound page.
Link: http://lkml.kernel.org/r/20170104023954.13451.5678.stgit@localhost.localdomain
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Page fragment updates", v4.
This patch series takes care of a few cleanups for the page fragments
API.
First we do some renames so that things are much more consistent. First
we move the page_frag_ portion of the name to the front of the functions
names. Secondly we split out the cache specific functions from the
other page fragment functions by adding the word "cache" to the name.
Finally I added a bit of documentation that will hopefully help to
explain some of this. I plan to revisit this later as we get things
more ironed out in the near future with the changes planned for the DMA
setup to support eXpress Data Path.
This patch (of 3):
This patch renames the page frag functions to be more consistent with
other APIs. Specifically we place the name page_frag first in the name
and then have either an alloc or free call name that we append as the
suffix. This makes it a bit clearer in terms of naming.
In addition we drop the leading double underscores since we are
technically no longer a backing interface and instead the front end that
is called from the networking APIs.
Link: http://lkml.kernel.org/r/20170104023854.13451.67390.stgit@localhost.localdomain
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The VM_BUG_ON() check in move_freepages() checks whether the node id of
a page matches the node id of its zone. However, it does this before
having checked whether the struct page pointer refers to a valid struct
page to begin with. This is guaranteed in most cases, but may not be
the case if CONFIG_HOLES_IN_ZONE=y.
So reorder the VM_BUG_ON() with the pfn_valid_within() check.
Link: http://lkml.kernel.org/r/1481706707-6211-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Robert Richter <rrichter@cavium.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The flag was introduced by commit 78afd5612d ("mm: add
__GFP_OTHER_NODE flag") to allow proper accounting of remote node
allocations done by kernel daemons on behalf of a process - e.g.
khugepaged.
After "mm: fix remote numa hits statistics" we do not need and actually
use the flag so we can safely remove it because all allocations which
are satisfied from their "home" node are accounted properly.
[mhocko@suse.com: fix build]
Link: http://lkml.kernel.org/r/20170106122225.GK5556@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170102153057.9451-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jia He has noticed that commit b9f00e147f ("mm, page_alloc: reduce
branches in zone_statistics") has an unintentional side effect that
remote node allocation requests are accounted as NUMA_MISS rathat than
NUMA_HIT and NUMA_OTHER if such a request doesn't use __GFP_OTHER_NODE.
There are many of these potentially because the flag is used very rarely
while we have many users of __alloc_pages_node.
Fix this by simply ignoring __GFP_OTHER_NODE (it can be removed in a
follow up patch) and treat all allocations that were satisfied from the
preferred zone's node as NUMA_HITS because this is the same node we
requested the allocation from in most cases. If this is not the local
node then we just account it as NUMA_OTHER rather than NUMA_LOCAL.
One downsize would be that an allocation request for a node which is
outside of the mempolicy nodemask would be reported as a hit which is a
bit weird but that was the case before b9f00e147f already.
Fixes: b9f00e147f ("mm, page_alloc: reduce branches in zone_statistics")
Link: http://lkml.kernel.org/r/20170102153057.9451-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Jia He <hejianet@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz> # with cbmc[1] superpowers
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a function that allows us to batch free a page that has multiple
references outstanding. Specifically this function can be used to drop
a page being used in the page frag alloc cache. With this drivers can
make use of functionality similar to the page frag alloc cache without
having to do any workarounds for the fact that there is no function that
frees multiple references.
Link: http://lkml.kernel.org/r/20161110113606.76501.70752.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
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>
Merge updates from Andrew Morton:
- various misc bits
- most of MM (quite a lot of MM material is awaiting the merge of
linux-next dependencies)
- kasan
- printk updates
- procfs updates
- MAINTAINERS
- /lib updates
- checkpatch updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (123 commits)
init: reduce rootwait polling interval time to 5ms
binfmt_elf: use vmalloc() for allocation of vma_filesz
checkpatch: don't emit unified-diff error for rename-only patches
checkpatch: don't check c99 types like uint8_t under tools
checkpatch: avoid multiple line dereferences
checkpatch: don't check .pl files, improve absolute path commit log test
scripts/checkpatch.pl: fix spelling
checkpatch: don't try to get maintained status when --no-tree is given
lib/ida: document locking requirements a bit better
lib/rbtree.c: fix typo in comment of ____rb_erase_color
lib/Kconfig.debug: make CONFIG_STRICT_DEVMEM depend on CONFIG_DEVMEM
MAINTAINERS: add drm and drm/i915 irc channels
MAINTAINERS: add "C:" for URI for chat where developers hang out
MAINTAINERS: add drm and drm/i915 bug filing info
MAINTAINERS: add "B:" for URI where to file bugs
get_maintainer: look for arbitrary letter prefixes in sections
printk: add Kconfig option to set default console loglevel
printk/sound: handle more message headers
printk/btrfs: handle more message headers
printk/kdb: handle more message headers
...
Pull smp hotplug updates from Thomas Gleixner:
"This is the final round of converting the notifier mess to the state
machine. The removal of the notifiers and the related infrastructure
will happen around rc1, as there are conversions outstanding in other
trees.
The whole exercise removed about 2000 lines of code in total and in
course of the conversion several dozen bugs got fixed. The new
mechanism allows to test almost every hotplug step standalone, so
usage sites can exercise all transitions extensively.
There is more room for improvement, like integrating all the
pointlessly different architecture mechanisms of synchronizing,
setting cpus online etc into the core code"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
tracing/rb: Init the CPU mask on allocation
soc/fsl/qbman: Convert to hotplug state machine
soc/fsl/qbman: Convert to hotplug state machine
zram: Convert to hotplug state machine
KVM/PPC/Book3S HV: Convert to hotplug state machine
arm64/cpuinfo: Convert to hotplug state machine
arm64/cpuinfo: Make hotplug notifier symmetric
mm/compaction: Convert to hotplug state machine
iommu/vt-d: Convert to hotplug state machine
mm/zswap: Convert pool to hotplug state machine
mm/zswap: Convert dst-mem to hotplug state machine
mm/zsmalloc: Convert to hotplug state machine
mm/vmstat: Convert to hotplug state machine
mm/vmstat: Avoid on each online CPU loops
mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead()
tracing/rb: Convert to hotplug state machine
oprofile/nmi timer: Convert to hotplug state machine
net/iucv: Use explicit clean up labels in iucv_init()
x86/pci/amd-bus: Convert to hotplug state machine
x86/oprofile/nmi: Convert to hotplug state machine
...
Vlastimil Babka pointed out that commit 479f854a20 ("mm, page_alloc:
defer debugging checks of pages allocated from the PCP") will allow the
per-cpu list counter to be out of sync with the per-cpu list contents if
a struct page is corrupted.
The consequence is an infinite loop if the per-cpu lists get fully
drained by free_pcppages_bulk because all the lists are empty but the
count is positive. The infinite loop occurs here
do {
batch_free++;
if (++migratetype == MIGRATE_PCPTYPES)
migratetype = 0;
list = &pcp->lists[migratetype];
} while (list_empty(list));
What the user sees is a bad page warning followed by a soft lockup with
interrupts disabled in free_pcppages_bulk().
This patch keeps the accounting in sync.
Fixes: 479f854a20 ("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
Link: http://lkml.kernel.org/r/20161202112951.23346-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org> [4.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, unreserve_highatomic_pageblock bails out if it found
highatomic pageblock regardless of really moving free pages from the one
so that it could mitigate unreserve logic's goal which saves OOM of a
process.
This patch makes unreserve functions bail out only if it moves some
pages out of !highatomic free list to avoid such false positive.
Another potential problem is that by race between page freeing and
reserve highatomic function, pages could be in highatomic free list even
though the pageblock is !high atomic migratetype. In that case,
unreserve_highatomic_pageblock can be void if count of highatomic
reserve is less than pageblock_nr_pages. We could solve it simply via
draining all of reserved pages before the OOM. It would have a
safeguard role to exhuast reserved pages before converging to OOM.
Link: http://lkml.kernel.org/r/1476259429-18279-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sangseok Lee <sangseok.lee@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is race between page freeing and unreserved highatomic.
CPU 0 CPU 1
free_hot_cold_page
mt = get_pfnblock_migratetype
set_pcppage_migratetype(page, mt)
unreserve_highatomic_pageblock
spin_lock_irqsave(&zone->lock)
move_freepages_block
set_pageblock_migratetype(page)
spin_unlock_irqrestore(&zone->lock)
free_pcppages_bulk
__free_one_page(mt) <- mt is stale
By above race, a page on CPU 0 could go non-highorderatomic free list
since the pageblock's type is changed. By that, unreserve logic of
highorderatomic can decrease reserved count on a same pageblock severak
times and then it will make mismatch between nr_reserved_highatomic and
the number of reserved pageblock.
So, this patch verifies whether the pageblock is highatomic or not and
decrease the count only if the pageblock is highatomic.
Link: http://lkml.kernel.org/r/1476259429-18279-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sangseok Lee <sangseok.lee@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "use up highorder free pages before OOM", v3.
I got OOM report from production team with v4.4 kernel. It had enough
free memory but failed to allocate GFP_KERNEL order-0 page and finally
encountered OOM kill. It occured during QA process which launches
several apps, switching and so on. It happned rarely. IOW, In normal
situation, it was not a problem but if we are unluck so that several
apps uses peak memory at the same time, it can happen. If we manage to
pass the phase, the system can go working well.
I could reproduce it with my test(memory spike easily. Look at below.
The reason is free pages(19M) of DMA32 zone are reserved for
HIGHORDERATOMIC and doesn't unreserved before the OOM.
balloon invoked oom-killer: gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), order=0, oom_score_adj=0
balloon cpuset=/ mems_allowed=0
CPU: 1 PID: 8473 Comm: balloon Tainted: G W OE 4.8.0-rc7-00219-g3f74c9559583-dirty #3161
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0x63/0x90
dump_header+0x5c/0x1ce
oom_kill_process+0x22e/0x400
out_of_memory+0x1ac/0x210
__alloc_pages_nodemask+0x101e/0x1040
handle_mm_fault+0xa0a/0xbf0
__do_page_fault+0x1dd/0x4d0
trace_do_page_fault+0x43/0x130
do_async_page_fault+0x1a/0xa0
async_page_fault+0x28/0x30
Mem-Info:
active_anon:383949 inactive_anon:106724 isolated_anon:0
active_file:15 inactive_file:44 isolated_file:0
unevictable:0 dirty:0 writeback:24 unstable:0
slab_reclaimable:2483 slab_unreclaimable:3326
mapped:0 shmem:0 pagetables:1906 bounce:0
free:6898 free_pcp:291 free_cma:0
Node 0 active_anon:1535796kB inactive_anon:426896kB active_file:60kB inactive_file:176kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:0kB writeback:96kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:1418 all_unreclaimable? no
DMA free:8188kB min:44kB low:56kB high:68kB active_anon:7648kB inactive_anon:0kB active_file:0kB inactive_file:4kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:20kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 1952 1952 1952
DMA32 free:19404kB min:5628kB low:7624kB high:9620kB active_anon:1528148kB inactive_anon:426896kB active_file:60kB inactive_file:420kB unevictable:0kB writepending:96kB present:2080640kB managed:2030092kB mlocked:0kB slab_reclaimable:9932kB slab_unreclaimable:13284kB kernel_stack:2496kB pagetables:7624kB bounce:0kB free_pcp:900kB local_pcp:112kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 2*4096kB (H) = 8192kB
DMA32: 7*4kB (H) 8*8kB (H) 30*16kB (H) 31*32kB (H) 14*64kB (H) 9*128kB (H) 2*256kB (H) 2*512kB (H) 4*1024kB (H) 5*2048kB (H) 0*4096kB = 19484kB
51131 total pagecache pages
50795 pages in swap cache
Swap cache stats: add 3532405601, delete 3532354806, find 124289150/1822712228
Free swap = 8kB
Total swap = 255996kB
524158 pages RAM
0 pages HighMem/MovableOnly
12658 pages reserved
0 pages cma reserved
0 pages hwpoisoned
Another example exceeded the limit by the race is
in:imklog: page allocation failure: order:0, mode:0x2280020(GFP_ATOMIC|__GFP_NOTRACK)
CPU: 0 PID: 476 Comm: in:imklog Tainted: G E 4.8.0-rc7-00217-g266ef83c51e5-dirty #3135
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0x63/0x90
warn_alloc_failed+0xdb/0x130
__alloc_pages_nodemask+0x4d6/0xdb0
new_slab+0x339/0x490
___slab_alloc.constprop.74+0x367/0x480
__slab_alloc.constprop.73+0x20/0x40
__kmalloc+0x1a4/0x1e0
alloc_indirect.isra.14+0x1d/0x50
virtqueue_add_sgs+0x1c4/0x470
__virtblk_add_req+0xae/0x1f0
virtio_queue_rq+0x12d/0x290
__blk_mq_run_hw_queue+0x239/0x370
blk_mq_run_hw_queue+0x8f/0xb0
blk_mq_insert_requests+0x18c/0x1a0
blk_mq_flush_plug_list+0x125/0x140
blk_flush_plug_list+0xc7/0x220
blk_finish_plug+0x2c/0x40
__do_page_cache_readahead+0x196/0x230
filemap_fault+0x448/0x4f0
ext4_filemap_fault+0x36/0x50
__do_fault+0x75/0x140
handle_mm_fault+0x84d/0xbe0
__do_page_fault+0x1dd/0x4d0
trace_do_page_fault+0x43/0x130
do_async_page_fault+0x1a/0xa0
async_page_fault+0x28/0x30
Mem-Info:
active_anon:363826 inactive_anon:121283 isolated_anon:32
active_file:65 inactive_file:152 isolated_file:0
unevictable:0 dirty:0 writeback:46 unstable:0
slab_reclaimable:2778 slab_unreclaimable:3070
mapped:112 shmem:0 pagetables:1822 bounce:0
free:9469 free_pcp:231 free_cma:0
Node 0 active_anon:1455304kB inactive_anon:485132kB active_file:260kB inactive_file:608kB unevictable:0kB isolated(anon):128kB isolated(file):0kB mapped:448kB dirty:0kB writeback:184kB shmem:0kB writeback_tmp:0kB unstable:0kB pages_scanned:13641 all_unreclaimable? no
DMA free:7748kB min:44kB low:56kB high:68kB active_anon:7944kB inactive_anon:104kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:108kB kernel_stack:0kB pagetables:4kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 1952 1952 1952
DMA32 free:30128kB min:5628kB low:7624kB high:9620kB active_anon:1447360kB inactive_anon:485028kB active_file:260kB inactive_file:608kB unevictable:0kB writepending:184kB present:2080640kB managed:2030132kB mlocked:0kB slab_reclaimable:11112kB slab_unreclaimable:12172kB kernel_stack:2400kB pagetables:7284kB bounce:0kB free_pcp:924kB local_pcp:72kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
DMA: 7*4kB (UE) 3*8kB (UH) 1*16kB (M) 0*32kB 2*64kB (U) 1*128kB (M) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (U) 1*4096kB (H) = 7748kB
DMA32: 10*4kB (H) 3*8kB (H) 47*16kB (H) 38*32kB (H) 5*64kB (H) 1*128kB (H) 2*256kB (H) 3*512kB (H) 3*1024kB (H) 3*2048kB (H) 4*4096kB (H) = 30128kB
2775 total pagecache pages
2536 pages in swap cache
Swap cache stats: add 206786828, delete 206784292, find 7323106/106686077
Free swap = 108744kB
Total swap = 255996kB
524158 pages RAM
0 pages HighMem/MovableOnly
12648 pages reserved
0 pages cma reserved
0 pages hwpoisoned
During the investigation, I found some problems with highatomic so this
patch aims to solve the problems and the final goal is to unreserve
every highatomic free pages before the OOM kill.
This patch (of 4):
In page freeing path, migratetype is racy so that a highorderatomic page
could free into non-highorderatomic free list. If that page is
allocated, VM can change the pageblock from higorderatomic to something.
In that case, highatomic pageblock accounting is broken so it doesn't
work(e.g., VM cannot reserve highorderatomic pageblocks any more
although it doesn't reach 1% limit).
So, this patch prohibits the changing from highatomic to other type.
It's no problem because MIGRATE_HIGHATOMIC is not listed in fallback
array so stealing will only happen due to unexpected races which is
really rare. Also, such prohibiting keeps highatomic pageblock more
longer so it would be better for highorderatomic page allocation.
Link: http://lkml.kernel.org/r/1476259429-18279-2-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sangseok Lee <sangseok.lee@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The stack frame size could grow too large when the plugin used long long
on 32-bit architectures when the given function had too many basic blocks.
The gcc warning was:
drivers/pci/hotplug/ibmphp_ebda.c: In function 'ibmphp_access_ebda':
drivers/pci/hotplug/ibmphp_ebda.c:409:1: warning: the frame size of 1108 bytes is larger than 1024 bytes [-Wframe-larger-than=]
This switches latent_entropy from u64 to unsigned long.
Thanks to PaX Team and Emese Revfy for the patch.
Signed-off-by: Kees Cook <keescook@chromium.org>
The per-zone waitqueues exist because of a scalability issue with the
page waitqueues on some NUMA machines, but it turns out that they hurt
normal loads, and now with the vmalloced stacks they also end up
breaking gfs2 that uses a bit_wait on a stack object:
wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE)
where 'gh' can be a reference to the local variable 'mount_gh' on the
stack of fill_super().
The reason the per-zone hash table breaks for this case is that there is
no "zone" for virtual allocations, and trying to look up the physical
page to get at it will fail (with a BUG_ON()).
It turns out that I actually complained to the mm people about the
per-zone hash table for another reason just a month ago: the zone lookup
also hurts the regular use of "unlock_page()" a lot, because the zone
lookup ends up forcing several unnecessary cache misses and generates
horrible code.
As part of that earlier discussion, we had a much better solution for
the NUMA scalability issue - by just making the page lock have a
separate contention bit, the waitqueue doesn't even have to be looked at
for the normal case.
Peter Zijlstra already has a patch for that, but let's see if anybody
even notices. In the meantime, let's fix the actual gfs2 breakage by
simplifying the bitlock waitqueues and removing the per-zone issue.
Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Tested-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus suggested we try to remove some of the low-hanging fruit related
to kernel address exposure in dmesg. The only leaks I see on my local
system are:
Freeing SMP alternatives memory: 32K (ffffffff9e309000 - ffffffff9e311000)
Freeing initrd memory: 10588K (ffffa0b736b42000 - ffffa0b737599000)
Freeing unused kernel memory: 3592K (ffffffff9df87000 - ffffffff9e309000)
Freeing unused kernel memory: 1352K (ffffa0b7288ae000 - ffffa0b728a00000)
Freeing unused kernel memory: 632K (ffffa0b728d62000 - ffffa0b728e00000)
Linus says:
"I suspect we should just remove [the addresses in the 'Freeing'
messages]. I'm sure they are useful in theory, but I suspect they
were more useful back when the whole "free init memory" was
originally done.
These days, if we have a use-after-free, I suspect the init-mem
situation is the easiest situation by far. Compared to all the dynamic
allocations which are much more likely to show it anyway. So having
debug output for that case is likely not all that productive."
With this patch the freeing messages now look like this:
Freeing SMP alternatives memory: 32K
Freeing initrd memory: 10588K
Freeing unused kernel memory: 3592K
Freeing unused kernel memory: 1352K
Freeing unused kernel memory: 632K
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/6836ff90c45b71d38e5d4405aec56fa9e5d1d4b2.1477405374.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.
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Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugins update from Kees Cook:
"This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot
time as possible, hoping to capitalize on any possible variation in
CPU operation (due to runtime data differences, hardware differences,
SMP ordering, thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example
for how to manipulate kernel code using the gcc plugin internals"
* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
latent_entropy: Mark functions with __latent_entropy
gcc-plugins: Add latent_entropy plugin
The __latent_entropy gcc attribute can be used only on functions and
variables. If it is on a function then the plugin will instrument it for
gathering control-flow entropy. If the attribute is on a variable then
the plugin will initialize it with random contents. The variable must
be an integer, an integer array type or a structure with integer fields.
These specific functions have been selected because they are init
functions (to help gather boot-time entropy), are called at unpredictable
times, or they have variable loops, each of which provide some level of
latent entropy.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.
The need for very-early boot entropy tends to be very architecture or
system design specific, so this plugin is more suited for those sorts
of special cases. The existing kernel RNG already attempts to extract
entropy from reliable runtime variation, but this plugin takes the idea to
a logical extreme by permuting a global variable based on any variation
in code execution (e.g. a different value (and permutation function)
is used to permute the global based on loop count, case statement,
if/then/else branching, etc).
To do this, the plugin starts by inserting a local variable in every
marked function. The plugin then adds logic so that the value of this
variable is modified by randomly chosen operations (add, xor and rol) and
random values (gcc generates separate static values for each location at
compile time and also injects the stack pointer at runtime). The resulting
value depends on the control flow path (e.g., loops and branches taken).
Before the function returns, the plugin mixes this local variable into
the latent_entropy global variable. The value of this global variable
is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
though it does not credit any bytes of entropy to the pool; the contents
of the global are just used to mix the pool.
Additionally, the plugin can pre-initialize arrays with build-time
random contents, so that two different kernel builds running on identical
hardware will not have the same starting values.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message and code comments]
Signed-off-by: Kees Cook <keescook@chromium.org>
Currently we do warn only about allocation failures but small
allocations are basically nofail and they might loop in the page
allocator for a long time. Especially when the reclaim cannot make any
progress - e.g. GFP_NOFS cannot invoke the oom killer and rely on a
different context to make a forward progress in case there is a lot
memory used by filesystems.
Give us at least a clue when something like this happens and warn about
allocations which take more than 10s. Print the basic allocation
context information along with the cumulative time spent in the
allocation as well as the allocation stack. Repeat the warning after
every 10 seconds so that we know that the problem is permanent rather
than ephemeral.
Link: http://lkml.kernel.org/r/20160929084407.7004-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
warn_alloc_failed is currently used from the page and vmalloc
allocators. This is a good reuse of the code except that vmalloc would
appreciate a slightly different warning message. This is already
handled by the fmt parameter except that
"%s: page allocation failure: order:%u, mode:%#x(%pGg)"
is printed anyway. This might be quite misleading because it might be a
vmalloc failure which leads to the warning while the page allocator is
not the culprit here. Fix this by always using the fmt string and only
print the context that makes sense for the particular context (e.g.
order makes only very little sense for the vmalloc context).
Rename the function to not miss any user and also because a later patch
will reuse it also for !failure cases.
Link: http://lkml.kernel.org/r/20160929084407.7004-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The should_reclaim_retry() makes decisions based on no_progress_loops,
so it makes sense to also update the counter there. It will be also
consistent with should_compact_retry() and compaction_retries. No
functional change.
[hillf.zj@alibaba-inc.com: fix missing pointer dereferences]
Link: http://lkml.kernel.org/r/20160926162025.21555-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The new ultimate compaction priority disables some heuristics, which may
result in excessive cost. This is fine for non-costly orders where we
want to try hard before resulting for OOM, but might be disruptive for
costly orders which do not trigger OOM and should generally have some
fallback. Thus, we disable the full priority for costly orders.
Suggested-by: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20160906135258.18335-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During reclaim/compaction loop, compaction priority can be increased by
the should_compact_retry() function, but the current code is not
optimal. Priority is only increased when compaction_failed() is true,
which means that compaction has scanned the whole zone. This may not
happen even after multiple attempts with a lower priority due to
parallel activity, so we might needlessly struggle on the lower
priorities and possibly run out of compaction retry attempts in the
process.
After this patch we are guaranteed at least one attempt at the highest
compaction priority even if we exhaust all retries at the lower
priorities.
Link: http://lkml.kernel.org/r/20160906135258.18335-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "reintroduce compaction feedback for OOM decisions".
After several people reported OOM's for order-2 allocations in 4.7 due
to Michal Hocko's OOM rework, he reverted the part that considered
compaction feedback [1] in the decisions to retry reclaim/compaction.
This was to provide a fix quickly for 4.8 rc and 4.7 stable series,
while mmotm had an almost complete solution that instead improved
compaction reliability.
This series completes the mmotm solution and reintroduces the compaction
feedback into OOM decisions. The first two patches restore the state of
mmotm before the temporary solution was merged, the last patch should be
the missing piece for reliability. The third patch restricts the
hardened compaction to non-costly orders, since costly orders don't
result in OOMs in the first place.
[1] http://marc.info/?i=20160822093249.GA14916%40dhcp22.suse.cz%3E
This patch (of 4):
Commit 6b4e3181d7 ("mm, oom: prevent premature OOM killer invocation
for high order request") was intended as a quick fix of OOM regressions
for 4.8 and stable 4.7.x kernels. For a better long-term solution, we
still want to consider compaction feedback, which should be possible
after some more improvements in the following patches.
This reverts commit 6b4e3181d7.
Link: http://lkml.kernel.org/r/20160906135258.18335-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently arch specific code can reserve memory blocks but
alloc_large_system_hash() may not take it into consideration when sizing
the hashes. This can lead to bigger hash than required and lead to no
available memory for other purposes. This is specifically true for
systems with CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled.
One approach to solve this problem would be to walk through the memblock
regions and calculate the available memory and base the size of hash
system on the available memory.
The other approach would be to depend on the architecture to provide the
number of pages that are reserved. This change provides hooks to allow
the architecture to provide the required info.
Link: http://lkml.kernel.org/r/1472476010-4709-2-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the existing enums instead of hardcoded index when looking at the
zonelist. This makes it more readable. No functionality change by this
patch.
Link: http://lkml.kernel.org/r/1472227078-24852-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Until now, if some page_ext users want to use it's own field on
page_ext, it should be defined in struct page_ext by hard-coding. It
has a problem that wastes memory in following situation.
struct page_ext {
#ifdef CONFIG_A
int a;
#endif
#ifdef CONFIG_B
int b;
#endif
};
Assume that kernel is built with both CONFIG_A and CONFIG_B. Even if we
enable feature A and doesn't enable feature B at runtime, each entry of
struct page_ext takes two int rather than one int. It's undesirable
result so this patch tries to fix it.
To solve above problem, this patch implements to support extra space
allocation at runtime. When need() callback returns true, it's extra
memory requirement is summed to entry size of page_ext. Also, offset
for each user's extra memory space is returned. With this offset, user
can use this extra space and there is no need to define needed field on
page_ext by hard-coding.
This patch only implements an infrastructure. Following patch will use
it for page_owner which is only user having it's own fields on page_ext.
Link: http://lkml.kernel.org/r/1471315879-32294-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
What debug_pagealloc does is just mapping/unmapping page table.
Basically, it doesn't need additional memory space to memorize
something. But, with guard page feature, it requires additional memory
to distinguish if the page is for guard or not. Guard page is only used
when debug_guardpage_minorder is non-zero so this patch removes
additional memory allocation (page_ext) if debug_guardpage_minorder is
zero.
It saves memory if we just use debug_pagealloc and not guard page.
Link: http://lkml.kernel.org/r/1471315879-32294-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Reduce memory waste by page extension user".
This patchset tries to reduce memory waste by page extension user.
First case is architecture supported debug_pagealloc. It doesn't
requires additional memory if guard page isn't used. 8 bytes per page
will be saved in this case.
Second case is related to page owner feature. Until now, if page_ext
users want to use it's own fields on page_ext, fields should be defined
in struct page_ext by hard-coding. It has a following problem.
struct page_ext {
#ifdef CONFIG_A
int a;
#endif
#ifdef CONFIG_B
int b;
#endif
};
Assume that kernel is built with both CONFIG_A and CONFIG_B. Even if we
enable feature A and doesn't enable feature B at runtime, each entry of
struct page_ext takes two int rather than one int. It's undesirable
waste so this patch tries to reduce it. By this patchset, we can save
20 bytes per page dedicated for page owner feature in some
configurations.
This patch (of 6):
We can make code clean by moving decision condition for set_page_guard()
into set_page_guard() itself. It will help code readability. There is
no functional change.
Link: http://lkml.kernel.org/r/1471315879-32294-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On x86_64 MAX_ORDER_NR_PAGES is usually 4M, and a pageblock is usually
2M, so we only set one pageblock's migratetype in deferred_free_range()
if pfn is aligned to MAX_ORDER_NR_PAGES. That means it causes
uninitialized migratetype blocks, you can see from "cat
/proc/pagetypeinfo", almost half blocks are Unmovable.
Also we missed freeing the last block in deferred_init_memmap(), it
causes memory leak.
Fixes: ac5d2539b2 ("mm: meminit: reduce number of times pageblocks are set during struct page init")
Link: http://lkml.kernel.org/r/57A3260F.4050709@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __compaction_suitable() function checks the low watermark plus a
compact_gap() gap to decide if there's enough free memory to perform
compaction. Then __isolate_free_page uses low watermark check to decide
if particular free page can be isolated. In the latter case, using low
watermark is needlessly pessimistic, as the free page isolations are
only temporary. For __compaction_suitable() the higher watermark makes
sense for high-order allocations where more freepages increase the
chance of success, and we can typically fail with some order-0 fallback
when the system is struggling to reach that watermark. But for
low-order allocation, forming the page should not be that hard. So
using low watermark here might just prevent compaction from even trying,
and eventually lead to OOM killer even if we are above min watermarks.
So after this patch, we use min watermark for non-costly orders in
__compaction_suitable(), and for all orders in __isolate_free_page().
[vbabka@suse.cz: clarify __isolate_free_page() comment]
Link: http://lkml.kernel.org/r/7ae4baec-4eca-e70b-2a69-94bea4fb19fa@suse.cz
Link: http://lkml.kernel.org/r/20160810091226.6709-11-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Lorenzo Stoakes <lstoakes@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __compaction_suitable() function checks the low watermark plus a
compact_gap() gap to decide if there's enough free memory to perform
compaction. This check uses direct compactor's alloc_flags, but that's
wrong, since these flags are not applicable for freepage isolation.
For example, alloc_flags may indicate access to memory reserves, making
compaction proceed, and then fail watermark check during the isolation.
A similar problem exists for ALLOC_CMA, which may be part of
alloc_flags, but not during freepage isolation. In this case however it
makes sense to use ALLOC_CMA both in __compaction_suitable() and
__isolate_free_page(), since there's actually nothing preventing the
freepage scanner to isolate from CMA pageblocks, with the assumption
that a page that could be migrated once by compaction can be migrated
also later by CMA allocation. Thus we should count pages in CMA
pageblocks when considering compaction suitability and when isolating
freepages.
To sum up, this patch should remove some false positives from
__compaction_suitable(), and allow compaction to proceed when free pages
required for compaction reside in the CMA pageblocks.
Link: http://lkml.kernel.org/r/20160810091226.6709-10-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Firmware Assisted Dump (FA_DUMP) on ppc64 reserves substantial amounts
of memory when booting a secondary kernel. Srikar Dronamraju reported
that multiple nodes may have no memory managed by the buddy allocator
but still return true for populated_zone().
Commit 1d82de618d ("mm, vmscan: make kswapd reclaim in terms of
nodes") was reported to cause kswapd to spin at 100% CPU usage when
fadump was enabled. The old code happened to deal with the situation of
a populated node with zero free pages by co-incidence but the current
code tries to reclaim populated zones without realising that is
impossible.
We cannot just convert populated_zone() as many existing users really
need to check for present_pages. This patch introduces a managed_zone()
helper and uses it in the few cases where it is critical that the check
is made for managed pages -- zonelist construction and page reclaim.
Link: http://lkml.kernel.org/r/20160831195104.GB8119@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There have been several reports about pre-mature OOM killer invocation
in 4.7 kernel when order-2 allocation request (for the kernel stack)
invoked OOM killer even during basic workloads (light IO or even kernel
compile on some filesystems). In all reported cases the memory is
fragmented and there are no order-2+ pages available. There is usually
a large amount of slab memory (usually dentries/inodes) and further
debugging has shown that there are way too many unmovable blocks which
are skipped during the compaction. Multiple reporters have confirmed
that the current linux-next which includes [1] and [2] helped and OOMs
are not reproducible anymore.
A simpler fix for the late rc and stable is to simply ignore the
compaction feedback and retry as long as there is a reclaim progress and
we are not getting OOM for order-0 pages. We already do that for
CONFING_COMPACTION=n so let's reuse the same code when compaction is
enabled as well.
[1] http://lkml.kernel.org/r/20160810091226.6709-1-vbabka@suse.cz
[2] http://lkml.kernel.org/r/f7a9ea9d-bb88-bfd6-e340-3a933559305a@suse.cz
Fixes: 0a0337e0d1 ("mm, oom: rework oom detection")
Link: http://lkml.kernel.org/r/20160823074339.GB23577@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Tested-by: Olaf Hering <olaf@aepfle.de>
Tested-by: Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>
Cc: Ralf-Peter Rohbeck <Ralf-Peter.Rohbeck@quantum.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org> [4.7.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
meminfo_proc_show() and si_mem_available() are using the wrong helpers
for calculating the size of the LRUs. The user-visible impact is that
there appears to be an abnormally high number of unevictable pages.
Link: http://lkml.kernel.org/r/20160805105805.GR2799@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some of node threshold depends on number of managed pages in the node.
When memory is going on/offline, it can be changed and we need to adjust
them.
Add recalculation to appropriate places and clean-up related functions
for better maintenance.
Link: http://lkml.kernel.org/r/1470724248-26780-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before resetting min_unmapped_pages, we need to initialize
min_unmapped_pages rather than min_slab_pages.
Fixes: a5f5f91da6 (mm: convert zone_reclaim to node_reclaim)
Link: http://lkml.kernel.org/r/1470724248-26780-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To distinguish non-slab pages charged to kmemcg we mark them PageKmemcg,
which sets page->_mapcount to -512. Currently, we set/clear PageKmemcg
in __alloc_pages_nodemask()/free_pages_prepare() for any page allocated
with __GFP_ACCOUNT, including those that aren't actually charged to any
cgroup, i.e. allocated from the root cgroup context. To avoid overhead
in case cgroups are not used, we only do that if memcg_kmem_enabled() is
true. The latter is set iff there are kmem-enabled memory cgroups
(online or offline). The root cgroup is not considered kmem-enabled.
As a result, if a page is allocated with __GFP_ACCOUNT for the root
cgroup when there are kmem-enabled memory cgroups and is freed after all
kmem-enabled memory cgroups were removed, e.g.
# no memory cgroups has been created yet, create one
mkdir /sys/fs/cgroup/memory/test
# run something allocating pages with __GFP_ACCOUNT, e.g.
# a program using pipe
dmesg | tail
# remove the memory cgroup
rmdir /sys/fs/cgroup/memory/test
we'll get bad page state bug complaining about page->_mapcount != -1:
BUG: Bad page state in process swapper/0 pfn:1fd945c
page:ffffea007f651700 count:0 mapcount:-511 mapping: (null) index:0x0
flags: 0x1000000000000000()
To avoid that, let's mark with PageKmemcg only those pages that are
actually charged to and hence pin a non-root memory cgroup.
Fixes: 4949148ad4 ("mm: charge/uncharge kmemcg from generic page allocator paths")
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Paul Mackerras and Reza Arbab reported that machines with memoryless
nodes fail when vmstats are refreshed. Paul reported an oops as follows
Unable to handle kernel paging request for data at address 0xff7a10000
Faulting instruction address: 0xc000000000270cd0
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.7.0-kvm+ #118
task: c000000ff0680010 task.stack: c000000ff0704000
NIP: c000000000270cd0 LR: c000000000270ce8 CTR: 0000000000000000
REGS: c000000ff0707900 TRAP: 0300 Not tainted (4.7.0-kvm+)
MSR: 9000000102009033 <SF,HV,VEC,EE,ME,IR,DR,RI,LE,TM[E]> CR: 846b6824 XER: 20000000
CFAR: c000000000008768 DAR: 0000000ff7a10000 DSISR: 42000000 SOFTE: 1
NIP refresh_zone_stat_thresholds+0x80/0x240
LR refresh_zone_stat_thresholds+0x98/0x240
Call Trace:
refresh_zone_stat_thresholds+0xb8/0x240 (unreliable)
Both supplied potential fixes but one potentially misses checks and
another had redundant initialisations. This version initialises
per_cpu_nodestats on a per-pgdat basis instead of on a per-zone basis.
Link: http://lkml.kernel.org/r/20160804092404.GI2799@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Paul Mackerras <paulus@ozlabs.org>
Reported-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There was only one use of __initdata_refok and __exit_refok
__init_refok was used 46 times against 82 for __ref.
Those definitions are obsolete since commit 312b1485fb ("Introduce new
section reference annotations tags: __ref, __refdata, __refconst")
This patch removes the following compatibility definitions and replaces
them treewide.
/* compatibility defines */
#define __init_refok __ref
#define __initdata_refok __refdata
#define __exit_refok __ref
I can also provide separate patches if necessary.
(One patch per tree and check in 1 month or 2 to remove old definitions)
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1466796271-3043-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Async compaction detects contention either due to failing trylock on
zone->lock or lru_lock, or by need_resched(). Since 1f9efdef4f ("mm,
compaction: khugepaged should not give up due to need_resched()") the
code got quite complicated to distinguish these two up to the
__alloc_pages_slowpath() level, so different decisions could be taken
for khugepaged allocations.
After the recent changes, khugepaged allocations don't check for
contended compaction anymore, so we again don't need to distinguish lock
and sched contention, and simplify the current convoluted code a lot.
However, I believe it's also possible to simplify even more and
completely remove the check for contended compaction after the initial
async compaction for costly orders, which was originally aimed at THP
page fault allocations. There are several reasons why this can be done
now:
- with the new defaults, THP page faults no longer do reclaim/compaction at
all, unless the system admin has overridden the default, or application has
indicated via madvise that it can benefit from THP's. In both cases, it
means that the potential extra latency is expected and worth the benefits.
- even if reclaim/compaction proceeds after this patch where it previously
wouldn't, the second compaction attempt is still async and will detect the
contention and back off, if the contention persists
- there are still heuristics like deferred compaction and pageblock skip bits
in place that prevent excessive THP page fault latencies
Link: http://lkml.kernel.org/r/20160721073614.24395-9-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the context of direct compaction, for some types of allocations we
would like the compaction to either succeed or definitely fail while
trying as hard as possible. Current async/sync_light migration mode is
insufficient, as there are heuristics such as caching scanner positions,
marking pageblocks as unsuitable or deferring compaction for a zone. At
least the final compaction attempt should be able to override these
heuristics.
To communicate how hard compaction should try, we replace migration mode
with a new enum compact_priority and change the relevant function
signatures. In compact_zone_order() where struct compact_control is
constructed, the priority is mapped to suitable control flags. This
patch itself has no functional change, as the current priority levels
are mapped back to the same migration modes as before. Expanding them
will be done next.
Note that !CONFIG_COMPACTION variant of try_to_compact_pages() is
removed, as the only caller exists under CONFIG_COMPACTION.
Link: http://lkml.kernel.org/r/20160721073614.24395-8-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After the previous patch, we can distinguish costly allocations that
should be really lightweight, such as THP page faults, with
__GFP_NORETRY. This means we don't need to recognize khugepaged
allocations via PF_KTHREAD anymore. We can also change THP page faults
in areas where madvise(MADV_HUGEPAGE) was used to try as hard as
khugepaged, as the process has indicated that it benefits from THP's and
is willing to pay some initial latency costs.
We can also make the flags handling less cryptic by distinguishing
GFP_TRANSHUGE_LIGHT (no reclaim at all, default mode in page fault) from
GFP_TRANSHUGE (only direct reclaim, khugepaged default). Adding
__GFP_NORETRY or __GFP_KSWAPD_RECLAIM is done where needed.
The patch effectively changes the current GFP_TRANSHUGE users as
follows:
* get_huge_zero_page() - the zero page lifetime should be relatively
long and it's shared by multiple users, so it's worth spending some
effort on it. We use GFP_TRANSHUGE, and __GFP_NORETRY is not added.
This also restores direct reclaim to this allocation, which was
unintentionally removed by commit e4a49efe4e7e ("mm: thp: set THP defrag
by default to madvise and add a stall-free defrag option")
* alloc_hugepage_khugepaged_gfpmask() - this is khugepaged, so latency
is not an issue. So if khugepaged "defrag" is enabled (the default), do
reclaim via GFP_TRANSHUGE without __GFP_NORETRY. We can remove the
PF_KTHREAD check from page alloc.
As a side-effect, khugepaged will now no longer check if the initial
compaction was deferred or contended. This is OK, as khugepaged sleep
times between collapsion attempts are long enough to prevent noticeable
disruption, so we should allow it to spend some effort.
* migrate_misplaced_transhuge_page() - already was masking out
__GFP_RECLAIM, so just convert to GFP_TRANSHUGE_LIGHT which is
equivalent.
* alloc_hugepage_direct_gfpmask() - vma's with VM_HUGEPAGE (via madvise)
are now allocating without __GFP_NORETRY. Other vma's keep using
__GFP_NORETRY if direct reclaim/compaction is at all allowed (by default
it's allowed only for madvised vma's). The rest is conversion to
GFP_TRANSHUGE(_LIGHT).
[mhocko@suse.com: suggested GFP_TRANSHUGE_LIGHT]
Link: http://lkml.kernel.org/r/20160721073614.24395-7-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since THP allocations during page faults can be costly, extra decisions
are employed for them to avoid excessive reclaim and compaction, if the
initial compaction doesn't look promising. The detection has never been
perfect as there is no gfp flag specific to THP allocations. At this
moment it checks the whole combination of flags that makes up
GFP_TRANSHUGE, and hopes that no other users of such combination exist,
or would mind being treated the same way. Extra care is also taken to
separate allocations from khugepaged, where latency doesn't matter that
much.
It is however possible to distinguish these allocations in a simpler and
more reliable way. The key observation is that after the initial
compaction followed by the first iteration of "standard"
reclaim/compaction, both __GFP_NORETRY allocations and costly
allocations without __GFP_REPEAT are declared as failures:
/* Do not loop if specifically requested */
if (gfp_mask & __GFP_NORETRY)
goto nopage;
/*
* Do not retry costly high order allocations unless they are
* __GFP_REPEAT
*/
if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_REPEAT))
goto nopage;
This means we can further distinguish allocations that are costly order
*and* additionally include the __GFP_NORETRY flag. As it happens,
GFP_TRANSHUGE allocations do already fall into this category. This will
also allow other costly allocations with similar high-order benefit vs
latency considerations to use this semantic. Furthermore, we can
distinguish THP allocations that should try a bit harder (such as from
khugepageed) by removing __GFP_NORETRY, as will be done in the next
patch.
Link: http://lkml.kernel.org/r/20160721073614.24395-6-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pavel Tatashin