Commit 1c5e0be3 authored Dec 28, 2018 by Michal Hocko Committed by Greg Kroah-Hartman Jan 13, 2019

memcg, oom: notify on oom killer invocation from the charge path

commit 7056d3a37d2c6aaaab10c13e8e69adc67ec1fc65 upstream.

Burt Holzman has noticed that memcg v1 doesn't notify about OOM events via
eventfd anymore.  The reason is that 29ef680a ("memcg, oom: move
out_of_memory back to the charge path") has moved the oom handling back to
the charge path.  While doing so the notification was left behind in
mem_cgroup_oom_synchronize.

Fix the issue by replicating the oom hierarchy locking and the
notification.

Link: http://lkml.kernel.org/r/20181224091107.18354-1-mhocko@kernel.org


Fixes: 29ef680a ("memcg, oom: move out_of_memory back to the charge path")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Burt Holzman <burt@fnal.gov>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com
Cc: <stable@vger.kernel.org>	[4.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 8da70752

mm/memcontrol.c

+18 −2

Original line number	Diff line number	Diff line
		@@ -1666,6 +1666,9 @@ enum oom_status {

		static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
		{
		enum oom_status ret;
		bool locked;

		if (order > PAGE_ALLOC_COSTLY_ORDER)
		return OOM_SKIPPED;

		@@ -1698,10 +1701,23 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int
		return OOM_ASYNC;
		}

		mem_cgroup_mark_under_oom(memcg);

		locked = mem_cgroup_oom_trylock(memcg);

		if (locked)
		mem_cgroup_oom_notify(memcg);

		mem_cgroup_unmark_under_oom(memcg);
		if (mem_cgroup_out_of_memory(memcg, mask, order))
		return OOM_SUCCESS;
		ret = OOM_SUCCESS;
		else
		ret = OOM_FAILED;

		return OOM_FAILED;
		if (locked)
		mem_cgroup_oom_unlock(memcg);

		return ret;
		}

		/**