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author | Haifeng Xu <haifeng.xu@shopee.com> | 2023-04-19 06:07:39 +0300 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-06-10 02:25:16 +0300 |
commit | 18b1d18bc2bd8f54e8df6bc8096185361a6d1b15 (patch) | |
tree | 2cdaabb2f0eba3a96129dd66e4ee21fc424bcb91 | |
parent | 857f21397f7113e4f764aa65fb0160eb7f404808 (diff) | |
download | linux-18b1d18bc2bd8f54e8df6bc8096185361a6d1b15.tar.xz |
memcg, oom: remove explicit wakeup in mem_cgroup_oom_synchronize()
Before commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the
charge path"), all memcg oom killers were delayed to page fault path. And
the explicit wakeup is used in this case:
thread A:
...
if (locked) { // complete oom-kill, hold the lock
mem_cgroup_oom_unlock(memcg);
...
}
...
thread B:
...
if (locked && !memcg->oom_kill_disable) {
...
} else {
schedule(); // can't acquire the lock
...
}
...
The reason is that thread A kicks off the OOM-killer, which leads to
wakeups from the uncharges of the exiting task. But thread B is not
guaranteed to see them if it enters the OOM path after the OOM kills but
before thread A releases the lock.
Now only oom_kill_disable case is handled from the #PF path. In that case
it is userspace to trigger the wake up not the #PF path itself. All
potential paths to free some charges are responsible to call
memcg_oom_recover() , so the explicit wakeup is not needed in the
mem_cgroup_oom_synchronize() path which doesn't release any memory itself.
Link: https://lkml.kernel.org/r/20230419030739.115845-2-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r-- | mm/memcontrol.c | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e8aead97454b..d31fb1e2cb33 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2028,15 +2028,8 @@ bool mem_cgroup_oom_synchronize(bool handle) mem_cgroup_unmark_under_oom(memcg); finish_wait(&memcg_oom_waitq, &owait.wait); - if (locked) { + if (locked) mem_cgroup_oom_unlock(memcg); - /* - * There is no guarantee that an OOM-lock contender - * sees the wakeups triggered by the OOM kill - * uncharges. Wake any sleepers explicitly. - */ - memcg_oom_recover(memcg); - } cleanup: current->memcg_in_oom = NULL; css_put(&memcg->css); |