History log of /openbmc/linux/mm/oom_kill.c (Results 101 – 125 of 2189)
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# 35ce8ae9 16-Jan-2022 Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull signal/exit/ptrace updates from Eric Biederman:
"This set of changes deletes some dead

Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull signal/exit/ptrace updates from Eric Biederman:
"This set of changes deletes some dead code, makes a lot of cleanups
which hopefully make the code easier to follow, and fixes bugs found
along the way.

The end-game which I have not yet reached yet is for fatal signals
that generate coredumps to be short-circuit deliverable from
complete_signal, for force_siginfo_to_task not to require changing
userspace configured signal delivery state, and for the ptrace stops
to always happen in locations where we can guarantee on all
architectures that the all of the registers are saved and available on
the stack.

Removal of profile_task_ext, profile_munmap, and profile_handoff_task
are the big successes for dead code removal this round.

A bunch of small bug fixes are included, as most of the issues
reported were small enough that they would not affect bisection so I
simply added the fixes and did not fold the fixes into the changes
they were fixing.

There was a bug that broke coredumps piped to systemd-coredump. I
dropped the change that caused that bug and replaced it entirely with
something much more restrained. Unfortunately that required some
rebasing.

Some successes after this set of changes: There are few enough calls
to do_exit to audit in a reasonable amount of time. The lifetime of
struct kthread now matches the lifetime of struct task, and the
pointer to struct kthread is no longer stored in set_child_tid. The
flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
removed. Issues where task->exit_code was examined with
signal->group_exit_code should been examined were fixed.

There are several loosely related changes included because I am
cleaning up and if I don't include them they will probably get lost.

The original postings of these changes can be found at:
https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org
https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org
https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org

I trimmed back the last set of changes to only the obviously correct
once. Simply because there was less time for review than I had hoped"

* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
ptrace/m68k: Stop open coding ptrace_report_syscall
ptrace: Remove unused regs argument from ptrace_report_syscall
ptrace: Remove second setting of PT_SEIZED in ptrace_attach
taskstats: Cleanup the use of task->exit_code
exit: Use the correct exit_code in /proc/<pid>/stat
exit: Fix the exit_code for wait_task_zombie
exit: Coredumps reach do_group_exit
exit: Remove profile_handoff_task
exit: Remove profile_task_exit & profile_munmap
signal: clean up kernel-doc comments
signal: Remove the helper signal_group_exit
signal: Rename group_exit_task group_exec_task
coredump: Stop setting signal->group_exit_task
signal: Remove SIGNAL_GROUP_COREDUMP
signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
signal: Make coredump handling explicit in complete_signal
signal: Have prepare_signal detect coredumps using signal->core_state
signal: Have the oom killer detect coredumps using signal->core_state
exit: Move force_uaccess back into do_exit
exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
...

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Revision tags: v5.15.15
# 762f99f4 15-Jan-2022 Dmitry Torokhov <dmitry.torokhov@gmail.com>

Merge branch 'next' into for-linus

Prepare input updates for 5.17 merge window.


# f56caeda 15-Jan-2022 Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:
"146 patches.

Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, vfs, and

Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:
"146 patches.

Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, vfs, and mm (slab-generic, slab, kmemleak,
dax, kasan, debug, pagecache, gup, shmem, frontswap, memremap,
memcg, selftests, pagemap, dma, vmalloc, memory-failure, hugetlb,
userfaultfd, vmscan, mempolicy, oom-kill, hugetlbfs, migration, thp,
ksm, page-poison, percpu, rmap, zswap, zram, cleanups, hmm, and
damon)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (146 commits)
mm/damon: hide kernel pointer from tracepoint event
mm/damon/vaddr: hide kernel pointer from damon_va_three_regions() failure log
mm/damon/vaddr: use pr_debug() for damon_va_three_regions() failure logging
mm/damon/dbgfs: remove an unnecessary variable
mm/damon: move the implementation of damon_insert_region to damon.h
mm/damon: add access checking for hugetlb pages
Docs/admin-guide/mm/damon/usage: update for schemes statistics
mm/damon/dbgfs: support all DAMOS stats
Docs/admin-guide/mm/damon/reclaim: document statistics parameters
mm/damon/reclaim: provide reclamation statistics
mm/damon/schemes: account how many times quota limit has exceeded
mm/damon/schemes: account scheme actions that successfully applied
mm/damon: remove a mistakenly added comment for a future feature
Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts
Docs/admin-guide/mm/damon/usage: mention tracepoint at the beginning
Docs/admin-guide/mm/damon/usage: remove redundant information
Docs/admin-guide/mm/damon/usage: update for scheme quotas and watermarks
mm/damon: convert macro functions to static inline functions
mm/damon: modify damon_rand() macro to static inline function
mm/damon: move damon_rand() definition into damon.h
...

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# f530243a 14-Jan-2022 Jann Horn <jannh@google.com>

mm, oom: OOM sysrq should always kill a process

The OOM kill sysrq (alt+sysrq+F) should allow the user to kill the
process with the highest OOM badness with a single execution.

However, at the mome

mm, oom: OOM sysrq should always kill a process

The OOM kill sysrq (alt+sysrq+F) should allow the user to kill the
process with the highest OOM badness with a single execution.

However, at the moment, the OOM kill can bail out if an OOM notifier
(e.g. the i915 one) says that it reclaimed a tiny amount of memory from
somewhere. That's probably not what the user wants, so skip the bailout
if the OOM was triggered via sysrq.

Link: https://lkml.kernel.org/r/20220106102605.635656-1-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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# ba535c1c 14-Jan-2022 Suren Baghdasaryan <surenb@google.com>

mm/oom_kill: allow process_mrelease to run under mmap_lock protection

With exit_mmap holding mmap_write_lock during free_pgtables call,
process_mrelease does not need to elevate mm->mm_users in orde

mm/oom_kill: allow process_mrelease to run under mmap_lock protection

With exit_mmap holding mmap_write_lock during free_pgtables call,
process_mrelease does not need to elevate mm->mm_users in order to
prevent exit_mmap from destrying pagetables while __oom_reap_task_mm is
walking the VMA tree. The change prevents process_mrelease from calling
the last mmput, which can lead to waiting for IO completion in exit_aio.

Link: https://lkml.kernel.org/r/20211209191325.3069345-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner <christian@brauner.io>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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# b6bf9abb 14-Jan-2022 Dan Schatzberg <schatzberg.dan@gmail.com>

mm/memcg: add oom_group_kill memory event

Our container agent wants to know when a container exits if it was OOM
killed or not to report to the user. We use memory.oom.group = 1 to
ensure that OOM

mm/memcg: add oom_group_kill memory event

Our container agent wants to know when a container exits if it was OOM
killed or not to report to the user. We use memory.oom.group = 1 to
ensure that OOM kills within the container's cgroup kill everything.
Existing memory.events are insufficient for knowing if this triggered:

1) Our current approach reads memory.events oom_kill and reports the
container was killed if the value is non-zero. This is erroneous in
some cases where containers create their children cgroups with
memory.oom.group=1 as such OOM kills will get counted against the
container cgroup's oom_kill counter despite not actually OOM killing
the entire container.

2) Reading memory.events.local will fail to identify OOM kills in leaf
cgroups (that don't set memory.oom.group) within the container
cgroup.

This patch adds a new oom_group_kill event when memory.oom.group
triggers to allow userspace to cleanly identify when an entire cgroup is
oom killed.

[schatzberg.dan@gmail.com: changes from Johannes and Chris]
Link: https://lkml.kernel.org/r/20211213162511.2492267-1-schatzberg.dan@gmail.com

Link: https://lkml.kernel.org/r/20211203162426.3375036-1-schatzberg.dan@gmail.com
Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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# 8a2094d6 10-Jan-2022 Jiri Kosina <jkosina@suse.cz>

Merge branch 'for-5.17/core' into for-linus

- support for USI style pens (Tero Kristo, Mika Westerberg)
- quirk for devices that need inverted X/Y axes (Alistair Francis)
- small core code cleanups

Merge branch 'for-5.17/core' into for-linus

- support for USI style pens (Tero Kristo, Mika Westerberg)
- quirk for devices that need inverted X/Y axes (Alistair Francis)
- small core code cleanups and deduplication (Benjamin Tissoires)

show more ...


Revision tags: v5.16, v5.15.10, v5.15.9, v5.15.8, v5.15.7, v5.15.6, v5.15.5, v5.15.4
# 98b24b16 19-Nov-2021 Eric W. Biederman <ebiederm@xmission.com>

signal: Have the oom killer detect coredumps using signal->core_state

In preparation for removing the flag SIGNAL_GROUP_COREDUMP, change
__task_will_free_mem to test signal->core_state instead of th

signal: Have the oom killer detect coredumps using signal->core_state

In preparation for removing the flag SIGNAL_GROUP_COREDUMP, change
__task_will_free_mem to test signal->core_state instead of the flag
SIGNAL_GROUP_COREDUMP.

Both fields are protected by siglock and both live in signal_struct so
there are no real tradeoffs here, just a change to which field is
being tested.

Link: https://lkml.kernel.org/r/20211213225350.27481-3-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

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# f81483aa 05-Jan-2022 Takashi Iwai <tiwai@suse.de>

Merge branch 'for-next' into for-linus

Pull 5.17 materials.

Signed-off-by: Takashi Iwai <tiwai@suse.de>


# 17580470 17-Dec-2021 Thomas Zimmermann <tzimmermann@suse.de>

Merge drm/drm-next into drm-misc-next-fixes

Backmerging to bring drm-misc-next-fixes up to the latest state for
the current release cycle.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>


# 86329873 09-Dec-2021 Daniel Lezcano <daniel.lezcano@linaro.org>

Merge branch 'reset/of-get-optional-exclusive' of git://git.pengutronix.de/pza/linux into timers/drivers/next

"Add optional variant of of_reset_control_get_exclusive(). If the
requested reset is not

Merge branch 'reset/of-get-optional-exclusive' of git://git.pengutronix.de/pza/linux into timers/drivers/next

"Add optional variant of of_reset_control_get_exclusive(). If the
requested reset is not specified in the device tree, this function
returns NULL instead of an error."

This dependency is needed for the Generic Timer Module (a.k.a OSTM)
support for RZ/G2L.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

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# 5d8dfaa7 09-Dec-2021 Dmitry Torokhov <dmitry.torokhov@gmail.com>

Merge tag 'v5.15' into next

Sync up with the mainline to get the latest APIs and DT bindings.


# 448cc2fb 22-Nov-2021 Jani Nikula <jani.nikula@intel.com>

Merge drm/drm-next into drm-intel-next

Sync up with drm-next to get v5.16-rc2.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>


# 8626afb1 22-Nov-2021 Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Merge drm/drm-next into drm-intel-gt-next

Thomas needs the dma_resv_for_each_fence API for i915/ttm async migration
work.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>


Revision tags: v5.15.3
# a713ca23 18-Nov-2021 Thomas Zimmermann <tzimmermann@suse.de>

Merge drm/drm-next into drm-misc-next

Backmerging from drm/drm-next for v5.16-rc1.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>


# 467dd91e 16-Nov-2021 Maxime Ripard <maxime@cerno.tech>

Merge drm/drm-fixes into drm-misc-fixes

We need -rc1 to address a breakage in drm/scheduler affecting panfrost.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>


Revision tags: v5.15.2
# 447212bb 11-Nov-2021 Dave Airlie <airlied@redhat.com>

BackMerge tag 'v5.15' into drm-next

I got a drm-fixes which had some 5.15 stuff in it, so to avoid
the mess just backmerge here.

Linux 5.15

Signed-off-by: Dave Airlie <airlied@redhat.com>


# 6752de1a 10-Nov-2021 Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'pidfd.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull pidfd updates from Christian Brauner:
"Various places in the kernel have picked up pidfds.

The two mos

Merge tag 'pidfd.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull pidfd updates from Christian Brauner:
"Various places in the kernel have picked up pidfds.

The two most recent additions have probably been the ability to use
pidfds in bpf maps and the usage of pidfds in mm-based syscalls such
as process_mrelease() and process_madvise().

The same pattern to turn a pidfd into a struct task exists in two
places. One of those places used PIDTYPE_TGID while the other one used
PIDTYPE_PID even though it is clearly documented in all pidfd-helpers
that pidfds __currently__ only refer to thread-group leaders (subject
to change in the future if need be).

This isn't a bug per se but has the potential to be one if we allow
pidfds to refer to individual threads. If that happens we want to
audit all codepaths that make use of them to ensure they can deal with
pidfds refering to individual threads.

This adds a simple helper to turn a pidfd into a struct task making it
easy to grep for such places. Plus, it gets rid of code-duplication"

* tag 'pidfd.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
mm: use pidfd_get_task()
pid: add pidfd_get_task() helper

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# 512b7931 06-Nov-2021 Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:
"257 patches.

Subsystems affected by this patch series: scripts, ocfs2, vfs, and
mm (slab-generic, slab, slub,

Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:
"257 patches.

Subsystems affected by this patch series: scripts, ocfs2, vfs, and
mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
cleanups, kfence, and damon)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits)
mm/damon: remove return value from before_terminate callback
mm/damon: fix a few spelling mistakes in comments and a pr_debug message
mm/damon: simplify stop mechanism
Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
Docs/admin-guide/mm/damon/start: simplify the content
Docs/admin-guide/mm/damon/start: fix a wrong link
Docs/admin-guide/mm/damon/start: fix wrong example commands
mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
mm/damon: remove unnecessary variable initialization
Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
selftests/damon: support watermarks
mm/damon/dbgfs: support watermarks
mm/damon/schemes: activate schemes based on a watermarks mechanism
tools/selftests/damon: update for regions prioritization of schemes
mm/damon/dbgfs: support prioritization weights
mm/damon/vaddr,paddr: support pageout prioritization
mm/damon/schemes: prioritize regions within the quotas
mm/damon/selftests: support schemes quotas
mm/damon/dbgfs: support quotas of schemes
...

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Revision tags: v5.15.1
# 3723929e 05-Nov-2021 Sultan Alsawaf <sultan@kerneltoast.com>

mm: mark the OOM reaper thread as freezable

The OOM reaper alters user address space which might theoretically alter
the snapshot if reaping is allowed to happen after the freezer quiescent
state.

mm: mark the OOM reaper thread as freezable

The OOM reaper alters user address space which might theoretically alter
the snapshot if reaping is allowed to happen after the freezer quiescent
state. To this end, the reaper kthread uses wait_event_freezable()
while waiting for any work so that it cannot run while the system
freezes.

However, the current implementation doesn't respect the freezer because
all kernel threads are created with the PF_NOFREEZE flag, so they are
automatically excluded from freezing operations. This means that the
OOM reaper can race with system snapshotting if it has work to do while
the system is being frozen.

Fix this by adding a set_freezable() call which will clear the
PF_NOFREEZE flag and thus make the OOM reaper visible to the freezer.

Please note that the OOM reaper altering the snapshot this way is mostly
a theoretical concern and has not been observed in practice.

Link: https://lkml.kernel.org/r/20210921165758.6154-1-sultan@kerneltoast.com
Link: https://lkml.kernel.org/r/20210918233920.9174-1-sultan@kerneltoast.com
Fixes: aac453635549 ("mm, oom: introduce oom reaper")
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...


# 60e2793d 05-Nov-2021 Michal Hocko <mhocko@suse.com>

mm, oom: do not trigger out_of_memory from the #PF

Any allocation failure during the #PF path will return with VM_FAULT_OOM
which in turn results in pagefault_out_of_memory. This can happen for 2
d

mm, oom: do not trigger out_of_memory from the #PF

Any allocation failure during the #PF path will return with VM_FAULT_OOM
which in turn results in pagefault_out_of_memory. This can happen for 2
different reasons. a) Memcg is out of memory and we rely on
mem_cgroup_oom_synchronize to perform the memcg OOM handling or b)
normal allocation fails.

The latter is quite problematic because allocation paths already trigger
out_of_memory and the page allocator tries really hard to not fail
allocations. Anyway, if the OOM killer has been already invoked there
is no reason to invoke it again from the #PF path. Especially when the
OOM condition might be gone by that time and we have no way to find out
other than allocate.

Moreover if the allocation failed and the OOM killer hasn't been invoked
then we are unlikely to do the right thing from the #PF context because
we have already lost the allocation context and restictions and
therefore might oom kill a task from a different NUMA domain.

This all suggests that there is no legitimate reason to trigger
out_of_memory from pagefault_out_of_memory so drop it. Just to be sure
that no #PF path returns with VM_FAULT_OOM without allocation print a
warning that this is happening before we restart the #PF.

[VvS: #PF allocation can hit into limit of cgroup v1 kmem controller.
This is a local problem related to memcg, however, it causes unnecessary
global OOM kills that are repeated over and over again and escalate into a
real disaster. This has been broken since kmem accounting has been
introduced for cgroup v1 (3.8). There was no kmem specific reclaim for
the separate limit so the only way to handle kmem hard limit was to return
with ENOMEM. In upstream the problem will be fixed by removing the
outdated kmem limit, however stable and LTS kernels cannot do it and are
still affected. This patch fixes the problem and should be backported
into stable/LTS.]

Link: https://lkml.kernel.org/r/f5fd8dd8-0ad4-c524-5f65-920b01972a42@virtuozzo.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...


# 0b28179a 05-Nov-2021 Vasily Averin <vvs@virtuozzo.com>

mm, oom: pagefault_out_of_memory: don't force global OOM for dying tasks

Patch series "memcg: prohibit unconditional exceeding the limit of dying tasks", v3.

Memory cgroup charging allows killed or

mm, oom: pagefault_out_of_memory: don't force global OOM for dying tasks

Patch series "memcg: prohibit unconditional exceeding the limit of dying tasks", v3.

Memory cgroup charging allows killed or exiting tasks to exceed the hard
limit. It can be misused and allowed to trigger global OOM from inside
a memcg-limited container. On the other hand if memcg fails allocation,
called from inside #PF handler it triggers global OOM from inside
pagefault_out_of_memory().

To prevent these problems this patchset:
(a) removes execution of out_of_memory() from
pagefault_out_of_memory(), becasue nobody can explain why it is
necessary.
(b) allow memcg to fail allocation of dying/killed tasks.

This patch (of 3):

Any allocation failure during the #PF path will return with VM_FAULT_OOM
which in turn results in pagefault_out_of_memory which in turn executes
out_out_memory() and can kill a random task.

An allocation might fail when the current task is the oom victim and
there are no memory reserves left. The OOM killer is already handled at
the page allocator level for the global OOM and at the charging level
for the memcg one. Both have much more information about the scope of
allocation/charge request. This means that either the OOM killer has
been invoked properly and didn't lead to the allocation success or it
has been skipped because it couldn't have been invoked. In both cases
triggering it from here is pointless and even harmful.

It makes much more sense to let the killed task die rather than to wake
up an eternally hungry oom-killer and send him to choose a fatter victim
for breakfast.

Link: https://lkml.kernel.org/r/0828a149-786e-7c06-b70a-52d086818ea3@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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# 7f9f8792 06-Nov-2021 Arnaldo Carvalho de Melo <acme@redhat.com>

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up some tools/perf/ patches that went via tip/perf/core, such
as:

tools/perf: Add mem_hops field in perf_mem_data_src structu

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up some tools/perf/ patches that went via tip/perf/core, such
as:

tools/perf: Add mem_hops field in perf_mem_data_src structure

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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# 820e9906 05-Nov-2021 Jiri Kosina <jkosina@suse.cz>

Merge branch 'for-5.16/asus' into for-linus


# a602285a 03-Nov-2021 Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull per signal_struct coredumps from Eric Biederman:
"Current coredump

Merge branch 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull per signal_struct coredumps from Eric Biederman:
"Current coredumps are mixed up with the exit code, the signal handling
code, and the ptrace code making coredumps much more complicated than
necessary and difficult to follow.

This series of changes starts with ptrace_stop and cleans it up,
making it easier to follow what is happening in ptrace_stop. Then
cleans up the exec interactions with coredumps. Then cleans up the
coredump interactions with exit. Finally the coredump interactions
with the signal handling code is cleaned up.

The first and last changes are bug fixes for minor bugs.

I believe the fact that vfork followed by execve can kill the process
the called vfork if exec fails is sufficient justification to change
the userspace visible behavior.

In previous discussions some of these changes were organized
differently and individually appeared to make the code base worse. As
currently written I believe they all stand on their own as cleanups
and bug fixes.

Which means that even if the worst should happen and the last change
needs to be reverted for some unimaginable reason, the code base will
still be improved.

If the worst does not happen there are a more cleanups that can be
made. Signals that generate coredumps can easily become eligible for
short circuit delivery in complete_signal. The entire rendezvous for
generating a coredump can move into get_signal. The function
force_sig_info_to_task be written in a way that does not modify the
signal handling state of the target task (because coredumps are
eligible for short circuit delivery). Many of these future cleanups
can be done another way but nothing so cleanly as if coredumps become
per signal_struct"

* 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
coredump: Limit coredumps to a single thread group
coredump: Don't perform any cleanups before dumping core
exit: Factor coredump_exit_mm out of exit_mm
exec: Check for a pending fatal signal instead of core_state
ptrace: Remove the unnecessary arguments from arch_ptrace_stop
signal: Remove the bogus sigkill_pending in ptrace_stop

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