There are several places where parameter descriptions do no match the
actual code. Fix it.
Link: http://lkml.kernel.org/r/1516700871-22279-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
so that kernel-doc will properly recognize the parameter and function
descriptions.
Link: http://lkml.kernel.org/r/1516700871-22279-2-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make memblock_is_map/region_memory return bool due to these two
functions only using either true or false as its return value.
No functional change.
Link: http://lkml.kernel.org/r/1513266622-15860-2-git-send-email-baiyaowei@cmss.chinamobile.com
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The file was converted from print_symbol() to %pSR a while ago in commit
071361d347 ("mm: Convert print_symbol to %pSR"). kallsyms does not
seem to be needed anymore.
Link: http://lkml.kernel.org/r/20171208025616.16267-3-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.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>
These duplicate includes have been found with scripts/checkincludes.pl but
they have been removed manually to avoid removing false positives.
Link: http://lkml.kernel.org/r/1512580957-6071-1-git-send-email-pravin.shedge4linux@gmail.com
Signed-off-by: Pravin Shedge <pravin.shedge4linux@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several functions that do find_task_by_vpid() followed by
get_task_struct(). We can use a helper function instead.
Link: http://lkml.kernel.org/r/1509602027-11337-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both of these functions deal with freeing of slab objects.
However, kasan_poison_kfree() mishandles SLAB_TYPESAFE_BY_RCU
(must also not poison such objects) and does not detect double-frees.
Unify code between these functions.
This solves both of the problems and allows to add more common code
(e.g. detection of invalid frees).
Link: http://lkml.kernel.org/r/385493d863acf60408be219a021c3c8e27daa96f.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Detect frees of pointers into middle of mempool objects.
I did a one-off test, but it turned out to be very tricky, so I reverted
it. First, mempool does not call kasan_poison_kfree() unless allocation
function fails. I stubbed an allocation function to fail on second and
subsequent allocations. But then mempool stopped to call
kasan_poison_kfree() at all, because it does it only when allocation
function is mempool_kmalloc(). We could support this special failing
test allocation function in mempool, but it also can't live with kasan
tests, because these are in a module.
Link: http://lkml.kernel.org/r/bf7a7d035d7a5ed62d2dd0e3d2e8a4fcdf456aa7.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__builtin_return_address(1) is unreliable without frame pointers.
With defconfig on kmalloc_pagealloc_invalid_free test I am getting:
BUG: KASAN: double-free or invalid-free in (null)
Pass caller PC from callers explicitly.
Link: http://lkml.kernel.org/r/9b01bc2d237a4df74ff8472a3bf6b7635908de01.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kasan: detect invalid frees".
KASAN detects double-frees, but does not detect invalid-frees (when a
pointer into a middle of heap object is passed to free). We recently had
a very unpleasant case in crypto code which freed an inner object inside
of a heap allocation. This left unnoticed during free, but totally
corrupted heap and later lead to a bunch of random crashes all over kernel
code.
Detect invalid frees.
This patch (of 5):
Detect frees of pointers into middle of large heap objects.
I dropped const from kasan_kfree_large() because it starts propagating
through a bunch of functions in kasan_report.c, slab/slub nearest_obj(),
all of their local variables, fixup_red_left(), etc.
Link: http://lkml.kernel.org/r/1b45b4fe1d20fc0de1329aab674c1dd973fee723.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As a code-size optimization, LLVM builds since r279383 may bulk-manipulate
the shadow region when (un)poisoning large memory blocks. This requires
new callbacks that simply do an uninstrumented memset().
This fixes linking the Clang-built kernel when using KASAN.
[arnd@arndb.de: add declarations for internal functions]
Link: http://lkml.kernel.org/r/20180105094112.2690475-1-arnd@arndb.de
[fengguang.wu@intel.com: __asan_set_shadow_00 can be static]
Link: http://lkml.kernel.org/r/20171223125943.GA74341@lkp-ib03
[ghackmann@google.com: fix memset() parameters, and tweak commit message to describe new callbacks]
Link: http://lkml.kernel.org/r/20171204191735.132544-6-paullawrence@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
clang's AddressSanitizer implementation adds redzones on either side of
alloca()ed buffers. These redzones are 32-byte aligned and at least 32
bytes long.
__asan_alloca_poison() is passed the size and address of the allocated
buffer, *excluding* the redzones on either side. The left redzone will
always be to the immediate left of this buffer; but AddressSanitizer may
need to add padding between the end of the buffer and the right redzone.
If there are any 8-byte chunks inside this padding, we should poison
those too.
__asan_allocas_unpoison() is just passed the top and bottom of the dynamic
stack area, so unpoisoning is simpler.
Link: http://lkml.kernel.org/r/20171204191735.132544-4-paullawrence@google.com
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
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
...
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass all
hardened usercopy checks since these sizes cannot change at runtime.)
This new check is WARN-by-default, so any mistakes can be found over the
next several releases without breaking anyone's system.
The series has roughly the following sections:
- remove %p and improve reporting with offset
- prepare infrastructure and whitelist kmalloc
- update VFS subsystem with whitelists
- update SCSI subsystem with whitelists
- update network subsystem with whitelists
- update process memory with whitelists
- update per-architecture thread_struct with whitelists
- update KVM with whitelists and fix ioctl bug
- mark all other allocations as not whitelisted
- update lkdtm for more sensible test overage
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Merge tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardened usercopy whitelisting from Kees Cook:
"Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs.
To further restrict what memory is available for copying, this creates
a way to whitelist specific areas of a given slab cache object for
copying to/from userspace, allowing much finer granularity of access
control.
Slab caches that are never exposed to userspace can declare no
whitelist for their objects, thereby keeping them unavailable to
userspace via dynamic copy operations. (Note, an implicit form of
whitelisting is the use of constant sizes in usercopy operations and
get_user()/put_user(); these bypass all hardened usercopy checks since
these sizes cannot change at runtime.)
This new check is WARN-by-default, so any mistakes can be found over
the next several releases without breaking anyone's system.
The series has roughly the following sections:
- remove %p and improve reporting with offset
- prepare infrastructure and whitelist kmalloc
- update VFS subsystem with whitelists
- update SCSI subsystem with whitelists
- update network subsystem with whitelists
- update process memory with whitelists
- update per-architecture thread_struct with whitelists
- update KVM with whitelists and fix ioctl bug
- mark all other allocations as not whitelisted
- update lkdtm for more sensible test overage"
* tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (38 commits)
lkdtm: Update usercopy tests for whitelisting
usercopy: Restrict non-usercopy caches to size 0
kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl
kvm: whitelist struct kvm_vcpu_arch
arm: Implement thread_struct whitelist for hardened usercopy
arm64: Implement thread_struct whitelist for hardened usercopy
x86: Implement thread_struct whitelist for hardened usercopy
fork: Provide usercopy whitelisting for task_struct
fork: Define usercopy region in thread_stack slab caches
fork: Define usercopy region in mm_struct slab caches
net: Restrict unwhitelisted proto caches to size 0
sctp: Copy struct sctp_sock.autoclose to userspace using put_user()
sctp: Define usercopy region in SCTP proto slab cache
caif: Define usercopy region in caif proto slab cache
ip: Define usercopy region in IP proto slab cache
net: Define usercopy region in struct proto slab cache
scsi: Define usercopy region in scsi_sense_cache slab cache
cifs: Define usercopy region in cifs_request slab cache
vxfs: Define usercopy region in vxfs_inode slab cache
ufs: Define usercopy region in ufs_inode_cache slab cache
...
This patch effectively reverts commit 9f1c2674b3 ("net: memcontrol:
defer call to mem_cgroup_sk_alloc()").
Moving mem_cgroup_sk_alloc() to the inet_csk_accept() completely breaks
memcg socket memory accounting, as packets received before memcg
pointer initialization are not accounted and are causing refcounting
underflow on socket release.
Actually the free-after-use problem was fixed by
commit c0576e3975 ("net: call cgroup_sk_alloc() earlier in
sk_clone_lock()") for the cgroup pointer.
So, let's revert it and call mem_cgroup_sk_alloc() just before
cgroup_sk_alloc(). This is safe, as we hold a reference to the socket
we're cloning, and it holds a reference to the memcg.
Also, let's drop BUG_ON(mem_cgroup_is_root()) check from
mem_cgroup_sk_alloc(). I see no reasons why bumping the root
memcg counter is a good reason to panic, and there are no realistic
ways to hit it.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix some basic kernel-doc notation in mm/swap.c:
- for function lru_cache_add_anon(), make its kernel-doc function name
match its function name and change colon to hyphen following the
function name
- for function pagevec_lookup_entries(), change the function parameter
name from nr_pages to nr_entries since that is more descriptive of
what the parameter actually is and then it matches the kernel-doc
comments also
Fix function kernel-doc to match the change in commit 67fd707f4681:
- drop the kernel-doc notation for @nr_pages from
pagevec_lookup_range() and correct the function description for that
change
Link: http://lkml.kernel.org/r/3b42ee3e-04a9-a6ca-6be4-f00752a114fe@infradead.org
Fixes: 67fd707f46 ("mm: remove nr_pages argument from pagevec_lookup_{,range}_tag()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
There are multiple comments surrounding do_fault_around that memtion
fault_around_pages() and fault_around_mask(), two routines that do not
exist. These comments should be reworded to reference
fault_around_bytes, the value which is used to determine how much
do_fault_around() will attempt to read when processing a fault.
These comments should have been updated when fault_around_pages() and
fault_around_mask() were removed in commit aecd6f4426 ("mm: close race
between do_fault_around() and fault_around_bytes_set()").
Fixes: aecd6f4426 ("mm: close race between do_fault_around() and fault_around_bytes_set()")
Link: http://lkml.kernel.org/r/302D0B14-C7E9-44C6-8BED-033F9ACBD030@oracle.com
Signed-off-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Larry Bassel <larry.bassel@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Workloads consisting of a large number of processes running the same
program with a very large shared data segment may experience performance
problems when numa balancing attempts to migrate the shared cow pages.
This manifests itself with many processes or tasks in
TASK_UNINTERRUPTIBLE state waiting for the shared pages to be migrated.
The program listed below simulates the conditions with these results
when run with 288 processes on a 144 core/8 socket machine.
Average throughput Average throughput Average throughput
with numa_balancing=0 with numa_balancing=1 with numa_balancing=1
without the patch with the patch
--------------------- --------------------- ---------------------
2118782 2021534 2107979
Complex production environments show less variability and fewer poorly
performing outliers accompanied with a smaller number of processes
waiting on NUMA page migration with this patch applied. In some cases,
%iowait drops from 16%-26% to 0.
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
*/
#include <sys/time.h>
#include <stdio.h>
#include <wait.h>
#include <sys/mman.h>
int a[1000000] = {13};
int main(int argc, const char **argv)
{
int n = 0;
int i;
pid_t pid;
int stat;
int *count_array;
int cpu_count = 288;
long total = 0;
struct timeval t1, t2 = {(argc > 1 ? atoi(argv[1]) : 10), 0};
if (argc > 2)
cpu_count = atoi(argv[2]);
count_array = mmap(NULL, cpu_count * sizeof(int),
(PROT_READ|PROT_WRITE),
(MAP_SHARED|MAP_ANONYMOUS), 0, 0);
if (count_array == MAP_FAILED) {
perror("mmap:");
return 0;
}
for (i = 0; i < cpu_count; ++i) {
pid = fork();
if (pid <= 0)
break;
if ((i & 0xf) == 0)
usleep(2);
}
if (pid != 0) {
if (i == 0) {
perror("fork:");
return 0;
}
for (;;) {
pid = wait(&stat);
if (pid < 0)
break;
}
for (i = 0; i < cpu_count; ++i)
total += count_array[i];
printf("Total %ld\n", total);
munmap(count_array, cpu_count * sizeof(int));
return 0;
}
gettimeofday(&t1, 0);
timeradd(&t1, &t2, &t1);
while (timercmp(&t2, &t1, <)) {
int b = 0;
int j;
for (j = 0; j < 1000000; j++)
b += a[j];
gettimeofday(&t2, 0);
n++;
}
count_array[i] = n;
return 0;
}
This patch changes change_pte_range() to skip shared copy-on-write pages
when called from change_prot_numa().
NOTE: change_prot_numa() is nominally called from task_numa_work() and
queue_pages_test_walk(). task_numa_work() is the auto NUMA balancing
path, and queue_pages_test_walk() is part of explicit NUMA policy
management. However, queue_pages_test_walk() only calls
change_prot_numa() when MPOL_MF_LAZY is specified and currently that is
not allowed, so change_prot_numa() is only called from auto NUMA
balancing.
In the case of explicit NUMA policy management, shared pages are not
migrated unless MPOL_MF_MOVE_ALL is specified, and MPOL_MF_MOVE_ALL
depends on CAP_SYS_NICE. Currently, there is no way to pass information
about MPOL_MF_MOVE_ALL to change_pte_range. This will have to be fixed
if MPOL_MF_LAZY is enabled and MPOL_MF_MOVE_ALL is to be honored in lazy
migration mode.
task_numa_work() skips the read-only VMAs of programs and shared
libraries.
Link: http://lkml.kernel.org/r/1516751617-7369-1-git-send-email-henry.willard@oracle.com
Signed-off-by: Henry Willard <henry.willard@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Dan Carpenter has noticed that mbind migration callback (new_page) can
get a NULL vma pointer and choke on it inside alloc_huge_page_vma which
relies on the VMA to get the hstate. We used to BUG_ON this case but
the BUG_+ON has been removed recently by "hugetlb, mempolicy: fix the
mbind hugetlb migration".
The proper way to handle this is to get the hstate from the migrated
page and rely on huge_node (resp. get_vma_policy) do the right thing
with null VMA. We are currently falling back to the default mempolicy
in that case which is in line what THP path is doing here.
Link: http://lkml.kernel.org/r/20180110104712.GR1732@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_mbind migration code relies on alloc_huge_page_noerr for hugetlb
pages. alloc_huge_page_noerr uses alloc_huge_page which is a highlevel
allocation function which has to take care of reserves, overcommit or
hugetlb cgroup accounting. None of that is really required for the page
migration because the new page is only temporal and either will replace
the original page or it will be dropped. This is essentially as for
other migration call paths and there shouldn't be any reason to handle
mbind in a special way.
The current implementation is even suboptimal because the migration
might fail just because the hugetlb cgroup limit is reached, or the
overcommit is saturated.
Fix this by making mbind like other hugetlb migration paths. Add a new
migration helper alloc_huge_page_vma as a wrapper around
alloc_huge_page_nodemask with additional mempolicy handling.
alloc_huge_page_noerr has no more users and it can go.
Link: http://lkml.kernel.org/r/20180103093213.26329-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hugetlb allocator has several layer of allocation functions depending
and the purpose of the allocation. There are two allocators depending
on whether the page can be allocated from the page allocator or we need
a contiguous allocator. This is currently opencoded in
alloc_fresh_huge_page which is the only path that might allocate giga
pages which require the later allocator. Create alloc_fresh_huge_page
which hides this implementation detail and use it in all callers which
hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page).
This shouldn't introduce any funtional change because both migration and
surplus allocators exlude giga pages explicitly.
While we are at it let's do some renaming. The current scheme is not
consistent and overly painfull to read and understand. Get rid of
prefix underscores from most functions. There is no real reason to make
names longer.
* alloc_fresh_huge_page is the new layer to abstract underlying
allocator
* __hugetlb_alloc_buddy_huge_page becomes shorter and neater
alloc_buddy_huge_page.
* Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put
the new page directly to the pool
* alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code
as it uses alloc_fresh_huge_page now
* others lose their excessive prefix underscores to make names shorter
[dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()]
Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda
Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
alloc_surplus_huge_page increases the pool size and the number of
surplus pages opportunistically to prevent from races with the pool size
change. See commit d1c3fb1f8f ("hugetlb: introduce
nr_overcommit_hugepages sysctl") for more details.
The resulting code is unnecessarily hairy, cause code duplication and
doesn't allow to share the allocation paths. Moreover pool size changes
tend to be very seldom so optimizing for them is not really reasonable.
Simplify the code and allow to allocate a fresh surplus page as long as
we are under the overcommit limit and then recheck the condition after
the allocation and drop the new page if the situation has changed. This
should provide a reasonable guarantee that an abrupt allocation requests
will not go way off the limit.
If we consider races with the pool shrinking and enlarging then we
should be reasonably safe as well. In the first case we are off by one
in the worst case and the second case should work OK because the page is
not yet visible. We can waste CPU cycles for the allocation but that
should be acceptable for a relatively rare condition.
Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hugepage migration relies on __alloc_buddy_huge_page to get a new page.
This has 2 main disadvantages.
1) it doesn't allow to migrate any huge page if the pool is used
completely which is not an exceptional case as the pool is static and
unused memory is just wasted.
2) it leads to a weird semantic when migration between two numa nodes
might increase the pool size of the destination NUMA node while the
page is in use. The issue is caused by per NUMA node surplus pages
tracking (see free_huge_page).
Address both issues by changing the way how we allocate and account
pages allocated for migration. Those should temporal by definition. So
we mark them that way (we will abuse page flags in the 3rd page) and
update free_huge_page to free such pages to the page allocator. Page
migration path then just transfers the temporal status from the new page
to the old one which will be freed on the last reference. The global
surplus count will never change during this path but we still have to be
careful when migrating a per-node suprlus page. This is now handled in
move_hugetlb_state which is called from the migration path and it copies
the hugetlb specific page state and fixes up the accounting when needed
Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better
reflect its purpose. The new allocation routine for the migration path
is __alloc_migrate_huge_page.
The user visible effect of this patch is that migrated pages are really
temporal and they travel between NUMA nodes as per the migration
request:
Before migration
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0
After
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0
with the previous implementation, both nodes would have nr_hugepages:1
until the page is freed.
Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Gigantic hugetlb pages were ingrown to the hugetlb code as an alien
specie with a lot of special casing. The allocation path is not an
exception. Unnecessarily so to be honest. It is true that the
underlying allocator is different but that is an implementation detail.
This patch unifies the hugetlb allocation path that a prepares fresh
pool pages. alloc_fresh_gigantic_page basically copies
alloc_fresh_huge_page logic so we can move everything there. This will
simplify set_max_huge_pages which doesn't have to care about what kind
of huge page we allocate.
Link: http://lkml.kernel.org/r/20180103093213.26329-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm, hugetlb: allocation API and migration improvements"
Motivation:
this is a follow up for [3] for the allocation API and [4] for the
hugetlb migration. It wasn't really easy to split those into two
separate patch series as they share some code.
My primary motivation to touch this code is to make the gigantic pages
migration working. The giga pages allocation code is just too fragile
and hacked into the hugetlb code now. This series tries to move giga
pages closer to the first class citizen. We are not there yet but
having 5 patches is quite a lot already and it will already make the
code much easier to follow. I will come with other changes on top after
this sees some review.
The first two patches should be trivial to review. The third patch
changes the way how we migrate huge pages. Newly allocated pages are a
subject of the overcommit check and they participate surplus accounting
which is quite unfortunate as the changelog explains. This patch
doesn't change anything wrt. giga pages.
Patch #4 removes the surplus accounting hack from
__alloc_surplus_huge_page. I hope I didn't miss anything there and a
deeper review is really due there.
Patch #5 finally unifies allocation paths and giga pages shouldn't be
any special anymore. There is also some renaming going on as well.
This patch (of 6):
hugetlb allocator has two entry points to the page allocator
- alloc_fresh_huge_page_node
- __hugetlb_alloc_buddy_huge_page
The two differ very subtly in two aspects. The first one doesn't care
about HTLB_BUDDY_* stats and it doesn't initialize the huge page.
prep_new_huge_page is not used because it not only initializes hugetlb
specific stuff but because it also put_page and releases the page to the
hugetlb pool which is not what is required in some contexts. This makes
things more complicated than necessary.
Simplify things by a) removing the page allocator entry point duplicity
and only keep __hugetlb_alloc_buddy_huge_page and b) make
prep_new_huge_page more reusable by removing the put_page which moves
the page to the allocator pool. All current callers are updated to call
put_page explicitly. Later patches will add new callers which won't
need it.
This patch shouldn't introduce any functional change.
Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem_cgroup_resize_[memsw]_limit() tries to free only 32
(SWAP_CLUSTER_MAX) pages on each iteration. This makes it practically
impossible to decrease limit of memory cgroup. Tasks could easily
allocate back 32 pages, so we can't reduce memory usage, and once
retry_count reaches zero we return -EBUSY.
Easy to reproduce the problem by running the following commands:
mkdir /sys/fs/cgroup/memory/test
echo $$ >> /sys/fs/cgroup/memory/test/tasks
cat big_file > /dev/null &
sleep 1 && echo $((100*1024*1024)) > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
-bash: echo: write error: Device or resource busy
Instead of relying on retry_count, keep retrying the reclaim until the
desired limit is reached or fail if the reclaim doesn't make any
progress or a signal is pending.
Link: http://lkml.kernel.org/r/20180119132544.19569-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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>
Fix the following sparse warning:
mm/memcontrol.c:1097:14: warning: symbol 'memcg1_stats' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/20180118193327.14200-1-chrisadr@gentoo.org
Signed-off-by: Christopher Díaz Riveros <chrisadr@gentoo.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The variable 'entry' is used before being initialized in
hmm_vma_walk_pmd().
No bad effect (beside performance hit) so !non_swap_entry(0) evaluate to
true which trigger a fault as if CPU was trying to access migrated
memory and migrate memory back from device memory to regular memory.
This function (hmm_vma_walk_pmd()) is called when a device driver tries
to populate its own page table. For migrated memory it should not
happen as the device driver should already have populated its page table
correctly during the migration.
Only case I can think of is multi-GPU where a second GPU triggers
migration back to regular memory. Again this would just result in a
performance hit, nothing bad would happen.
Link: http://lkml.kernel.org/r/20180122185759.26286-1-jglisse@redhat.com
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The comment is confusing. On the one hand, it refers to 32-bit
alignment (struct page alignment on 32-bit platforms), but this would
only guarantee that the 2 lowest bits must be zero. On the other hand,
it claims that at least 3 bits are available, and 3 bits are actually
used.
This is not broken, because there is a stronger alignment guarantee,
just less obvious. Let's fix the comment to make it clear how many bits
are available and why.
Although memmap arrays are allocated in various places, the resulting
pointer is encoded eventually, so I am adding a BUG_ON() here to enforce
at runtime that all expected bits are indeed available.
I have also added a BUILD_BUG_ON to check that PFN_SECTION_SHIFT is
sufficient, because this part of the calculation can be easily checked
at build time.
[ptesarik@suse.com: v2]
Link: http://lkml.kernel.org/r/20180125100516.589ea6af@ezekiel.suse.cz
Link: http://lkml.kernel.org/r/20180119080908.3a662e6f@ezekiel.suse.cz
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemi Wang <kemi.wang@intel.com>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"mode" argument is not used by try_to_compact_pages() and sub functions
anymore, it has been replaced by "prio". Fix the comment to explain the
use of "prio" argument.
Link: http://lkml.kernel.org/r/1515801336-20611-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@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>
static struct page_ext_operations *page_ext_ops[] always contains debug_guardpage_ops,
static struct page_ext_operations *page_ext_ops[] = {
&debug_guardpage_ops,
#ifdef CONFIG_PAGE_OWNER
&page_owner_ops,
#endif
...
}
but for it to work, CONFIG_DEBUG_PAGEALLOC must be enabled first. If
someone has CONFIG_PAGE_EXTENSION, but has none of its users, eg:
(CONFIG_PAGE_OWNER, CONFIG_DEBUG_PAGEALLOC, CONFIG_IDLE_PAGE_TRACKING),
we can shrink page_ext_init() to a simple retq.
$ size vmlinux (before patch)
text data bss dec hex filename
14356698 5681582 1687748 21726028 14b834c vmlinux
$ size vmlinux (after patch)
text data bss dec hex filename
14356008 5681538 1687748 21725294 14b806e vmlinux
On the other hand, it might does not even make sense, since if someone
enables CONFIG_PAGE_EXTENSION, I would expect him to enable also at
least one of its users.
Link: http://lkml.kernel.org/r/20180105130235.GA21241@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@techadventures.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem_cgroup_resize_limit() and mem_cgroup_resize_memsw_limit() have
identical logics. Refactor code so we don't need to keep two pieces of
code that does same thing.
Link: http://lkml.kernel.org/r/20180108224238.14583-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.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>
We waste sizeof(swp_entry_t) for zswap header when using zsmalloc as
zpool driver because zsmalloc doesn't support eviction.
Add zpool_evictable() to detect if zpool is potentially evictable, and
use it in zswap to avoid waste memory for zswap header.
[yuzhao@google.com: The zpool->" prefix is a result of copy & paste]
Link: http://lkml.kernel.org/r/20180110225626.110330-1-yuzhao@google.com
Link: http://lkml.kernel.org/r/20180110224741.83751-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Dan Streetman <ddstreet@ieee.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During our recent testing with fadvise(FADV_DONTNEED), we find that if
given offset/length is not page-aligned, the last page will not be
discarded. The tool we use is vmtouch (https://hoytech.com/vmtouch/),
we map a 10KB-sized file into memory and then try to run this tool to
evict the whole file mapping, but the last single page always remains
staying in the memory:
$./vmtouch -e test_10K
Files: 1
Directories: 0
Evicted Pages: 3 (12K)
Elapsed: 2.1e-05 seconds
$./vmtouch test_10K
Files: 1
Directories: 0
Resident Pages: 1/3 4K/12K 33.3%
Elapsed: 5.5e-05 seconds
However when we test with an older kernel, say 3.10, this problem is
gone. So we wonder if this is a regression:
$./vmtouch -e test_10K
Files: 1
Directories: 0
Evicted Pages: 3 (12K)
Elapsed: 8.2e-05 seconds
$./vmtouch test_10K
Files: 1
Directories: 0
Resident Pages: 0/3 0/12K 0% <-- partial page also discarded
Elapsed: 5e-05 seconds
After digging a little bit into this problem, we find it seems not a
regression. Not discarding partial page is likely to be on purpose
according to commit 441c228f81 ("mm: fadvise: document the
fadvise(FADV_DONTNEED) behaviour for partial pages") written by Mel
Gorman. He explained why partial pages should be preserved instead of
being discarded when using fadvise(FADV_DONTNEED).
However, the interesting part is that the actual code did NOT work as
the same as it was described, the partial page was still discarded
anyway, due to a calculation mistake of `end_index' passed to
invalidate_mapping_pages(). This mistake has not been fixed until
recently, that's why we fail to reproduce our problem in old kernels.
The fix is done in commit 18aba41cbf ("mm/fadvise.c: do not discard
partial pages with POSIX_FADV_DONTNEED") by Oleg Drokin.
Back to the original testing, our problem becomes that there is a
special case that, if the page-unaligned `endbyte' is also the end of
file, it is not necessary at all to preserve the last partial page, as
we all know no one else will use the rest of it. It should be safe
enough if we just discard the whole page. So we add an EOF check in
this patch.
We also find a poosbile real world issue in mainline kernel. Assume
such scenario: A userspace backup application want to backup a huge
amount of small files (<4k) at once, the developer might (I guess) want
to use fadvise(FADV_DONTNEED) to save memory. However, FADV_DONTNEED
won't really happen since the only page mapped is a partial page, and
kernel will preserve it. Our patch also fixes this problem, since we
know the endbyte is EOF, so we discard it.
Here is a simple reproducer to reproduce and verify each scenario we
described above:
test_fadvise.c
==============================
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char **argv)
{
int i, fd, ret, len;
struct stat buf;
void *addr;
unsigned char *vec;
char *strbuf;
ssize_t pagesize = getpagesize();
ssize_t filesize;
fd = open(argv[1], O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
if (fd < 0)
return -1;
filesize = strtoul(argv[2], NULL, 10);
strbuf = malloc(filesize);
memset(strbuf, 42, filesize);
write(fd, strbuf, filesize);
free(strbuf);
fsync(fd);
len = (filesize + pagesize - 1) / pagesize;
printf("length of pages: %d\n", len);
addr = mmap(NULL, filesize, PROT_READ, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED)
return -1;
ret = posix_fadvise(fd, 0, filesize, POSIX_FADV_DONTNEED);
if (ret < 0)
return -1;
vec = malloc(len);
ret = mincore(addr, filesize, (void *)vec);
if (ret < 0)
return -1;
for (i = 0; i < len; i++)
printf("pages[%d]: %x\n", i, vec[i] & 0x1);
free(vec);
close(fd);
return 0;
}
==============================
Test 1: running on kernel with commit 18aba41cbf reverted:
[root@caspar ~]# uname -r
4.15.0-rc6.revert+
[root@caspar ~]# ./test_fadvise file1 1024
length of pages: 1
pages[0]: 0 # <-- partial page discarded
[root@caspar ~]# ./test_fadvise file2 8192
length of pages: 2
pages[0]: 0
pages[1]: 0
[root@caspar ~]# ./test_fadvise file3 10240
length of pages: 3
pages[0]: 0
pages[1]: 0
pages[2]: 0 # <-- partial page discarded
Test 2: running on mainline kernel:
[root@caspar ~]# uname -r
4.15.0-rc6+
[root@caspar ~]# ./test_fadvise test1 1024
length of pages: 1
pages[0]: 1 # <-- partial and the only page not discarded
[root@caspar ~]# ./test_fadvise test2 8192
length of pages: 2
pages[0]: 0
pages[1]: 0
[root@caspar ~]# ./test_fadvise test3 10240
length of pages: 3
pages[0]: 0
pages[1]: 0
pages[2]: 1 # <-- partial page not discarded
Test 3: running on kernel with this patch:
[root@caspar ~]# uname -r
4.15.0-rc6.patched+
[root@caspar ~]# ./test_fadvise test1 1024
length of pages: 1
pages[0]: 0 # <-- partial page and EOF, discarded
[root@caspar ~]# ./test_fadvise test2 8192
length of pages: 2
pages[0]: 0
pages[1]: 0
[root@caspar ~]# ./test_fadvise test3 10240
length of pages: 3
pages[0]: 0
pages[1]: 0
pages[2]: 0 # <-- partial page and EOF, discarded
[akpm@linux-foundation.org: tweak code comment]
Link: http://lkml.kernel.org/r/5222da9ee20e1695eaabb69f631f200d6e6b8876.1515132470.git.jinli.zjl@alibaba-inc.com
Signed-off-by: shidao.ytt <shidao.ytt@alibaba-inc.com>
Signed-off-by: Caspar Zhang <jinli.zjl@alibaba-inc.com>
Reviewed-by: Oliver Yang <zhiche.yy@alibaba-inc.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>
Minchan Kim asked the following question -- what locks protects
address_space destroying when race happens between inode trauncation and
__isolate_lru_page? Jan Kara clarified by describing the race as follows
CPU1 CPU2
truncate(inode) __isolate_lru_page()
...
truncate_inode_page(mapping, page);
delete_from_page_cache(page)
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(page, NULL)
page_cache_tree_delete(..)
... mapping = page_mapping(page);
page->mapping = NULL;
...
spin_unlock_irqrestore(&mapping->tree_lock, flags);
page_cache_free_page(mapping, page)
put_page(page)
if (put_page_testzero(page)) -> false
- inode now has no pages and can be freed including embedded address_space
if (mapping && !mapping->a_ops->migratepage)
- we've dereferenced mapping which is potentially already free.
The race is theoretically possible but unlikely. Before the
delete_from_page_cache, truncate_cleanup_page is called so the page is
likely to be !PageDirty or PageWriteback which gets skipped by the only
caller that checks the mappping in __isolate_lru_page. Even if the race
occurs, a substantial amount of work has to happen during a tiny window
with no preemption but it could potentially be done using a virtual
machine to artifically slow one CPU or halt it during the critical
window.
This patch should eliminate the race with truncation by try-locking the
page before derefencing mapping and aborting if the lock was not
acquired. There was a suggestion from Huang Ying to use RCU as a
side-effect to prevent mapping being freed. However, I do not like the
solution as it's an unconventional means of preserving a mapping and
it's not a context where rcu_read_lock is obviously protecting rcu data.
Link: http://lkml.kernel.org/r/20180104102512.2qos3h5vqzeisrek@techsingularity.net
Fixes: c824493528 ("mm: compaction: make isolate_lru_page() filter-aware again")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Adapt add_seals()/get_seals() to work with hugetbfs-backed memory.
Teach memfd_create() to allow sealing operations on MFD_HUGETLB.
Link: http://lkml.kernel.org/r/20171107122800.25517-6-marcandre.lureau@redhat.com
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Those functions are called for memfd files, backed by shmem or hugetlb
(the next patches will handle hugetlb).
Link: http://lkml.kernel.org/r/20171107122800.25517-3-marcandre.lureau@redhat.com
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "memfd: add sealing to hugetlb-backed memory", v3.
Recently, Mike Kravetz added hugetlbfs support to memfd. However, he
didn't add sealing support. One of the reasons to use memfd is to have
shared memory sealing when doing IPC or sharing memory with another
process with some extra safety. qemu uses shared memory & hugetables
with vhost-user (used by dpdk), so it is reasonable to use memfd now
instead for convenience and security reasons.
This patch (of 9):
The functions are called through shmem_fcntl() only. And no danger in
removing the EXPORTs as the routines only work with shmem file structs.
Link: http://lkml.kernel.org/r/20171107122800.25517-2-marcandre.lureau@redhat.com
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Structure zs_pool has special flag to indicate success of shrinker
initialization. unregister_shrinker() has improved and can detect by
itself whether actual deinitialization should be performed or not, so
extra flag becomes redundant.
[akpm@linux-foundation.org: update comment (Aliaksei), remove unneeded cast]
Link: http://lkml.kernel.org/r/1513680552-9798-1-git-send-email-akaraliou.dev@gmail.com
Signed-off-by: Aliaksei Karaliou <akaraliou.dev@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: 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>
This uses the new annotation to determine if an mm has mmu notifiers
with blockable invalidate range callbacks to avoid oom reaping.
Otherwise, the callbacks are used around unmap_page_range().
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1712141330120.74052@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Dimitri Sivanich <sivanich@hpe.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 4d4bbd8526 ("mm, oom_reaper: skip mm structs with mmu
notifiers") prevented the oom reaper from unmapping private anonymous
memory with the oom reaper when the oom victim mm had mmu notifiers
registered.
The rationale is that doing mmu_notifier_invalidate_range_{start,end}()
around the unmap_page_range(), which is needed, can block and the oom
killer will stall forever waiting for the victim to exit, which may not
be possible without reaping.
That concern is real, but only true for mmu notifiers that have
blockable invalidate_range_{start,end}() callbacks. This patch adds a
"flags" field to mmu notifier ops that can set a bit to indicate that
these callbacks do not block.
The implementation is steered toward an expensive slowpath, such as
after the oom reaper has grabbed mm->mmap_sem of a still alive oom
victim.
[rientjes@google.com: mmu_notifier_invalidate_range_end() can also call the invalidate_range() must not block, fix comment]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1801091339570.240101@chino.kir.corp.google.com
[akpm@linux-foundation.org: make mm_has_blockable_invalidate_notifiers() return bool, use rwsem_is_locked()]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1712141329500.74052@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds