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Filename Latest commit message Latest commit date
Breno Leitao 25b5d466a9 memcg: always call cond_resched() after fn()
commit 06717a7b6c86514dbd6ab322e8083ffaa4db5712 upstream.

I am seeing soft lockup on certain machine types when a cgroup OOMs.  This
is happening because killing the process in certain machine might be very
slow, which causes the soft lockup and RCU stalls.  This happens usually
when the cgroup has MANY processes and memory.oom.group is set.

Example I am seeing in real production:

       [462012.244552] Memory cgroup out of memory: Killed process 3370438 (crosvm) ....
       ....
       [462037.318059] Memory cgroup out of memory: Killed process 4171372 (adb) ....
       [462037.348314] watchdog: BUG: soft lockup - CPU#64 stuck for 26s! [stat_manager-ag:1618982]
       ....

Quick look at why this is so slow, it seems to be related to serial flush
for certain machine types.  For all the crashes I saw, the target CPU was
at console_flush_all().

In the case above, there are thousands of processes in the cgroup, and it
is soft locking up before it reaches the 1024 limit in the code (which
would call the cond_resched()).  So, cond_resched() in 1024 blocks is not
sufficient.

Remove the counter-based conditional rescheduling logic and call
cond_resched() unconditionally after each task iteration, after fn() is
called.  This avoids the lockup independently of how slow fn() is.

Link: https://lkml.kernel.org/r/20250523-memcg_fix-v1-1-ad3eafb60477@debian.org
Fixes: ade81479c7dd ("memcg: fix soft lockup in the OOM process")
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Rik van Riel <riel@surriel.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Michael van der Westhuizen <rmikey@meta.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-04 14:32:35 +02:00
arch MIPS: pm-cps: Use per-CPU variables as per-CPU, not per-core 2025-06-04 14:32:33 +02:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-04-10 14:29:37 +02:00
certs
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:32:35 +02:00
Documentation x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 2025-06-04 14:32:32 +02:00
drivers drm/edid: fixed the bug that hdr metadata was not reset 2025-06-04 14:32:35 +02:00
fs __legitimize_mnt(): check for MNT_SYNC_UMOUNT should be under mount_lock 2025-06-04 14:32:35 +02:00
include ALSA: pcm: Fix race of buffer access at PCM OSS layer 2025-06-04 14:32:35 +02:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:39:28 +02:00
ipc
kernel rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y 2025-06-04 14:32:34 +02:00
lib dql: Fix dql->limit value when reset. 2025-06-04 14:32:30 +02:00
LICENSES
mm memcg: always call cond_resched() after fn() 2025-06-04 14:32:35 +02:00
net llc: fix data loss when reading from a socket in llc_ui_recvmsg() 2025-06-04 14:32:35 +02:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts kbuild: fix argument parsing in scripts/config 2025-06-04 14:32:31 +02:00
security smack: recognize ipv4 CIPSO w/o categories 2025-06-04 14:32:33 +02:00
sound ALSA: pcm: Fix race of buffer access at PCM OSS layer 2025-06-04 14:32:35 +02:00
tools bpftool: Fix readlink usage in get_fd_type 2025-06-04 14:32:34 +02:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.293 2025-05-02 07:39:30 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.