From: Michal Hocko <mhocko@kernel.org>
To: <linux-mm@kvack.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: [PATCH 2/2] memcg: do not report racy no-eligible OOM tasks
Date: Mon, 7 Jan 2019 15:38:02 +0100 [thread overview]
Message-ID: <20190107143802.16847-3-mhocko@kernel.org> (raw)
In-Reply-To: <20190107143802.16847-1-mhocko@kernel.org>
From: Michal Hocko <mhocko@suse.com>
Tetsuo has reported [1] that a single process group memcg might easily
swamp the log with no-eligible oom victim reports due to race between
the memcg charge and oom_reaper
Thread 1 Thread2 oom_reaper
try_charge try_charge
mem_cgroup_out_of_memory
mutex_lock(oom_lock)
mem_cgroup_out_of_memory
mutex_lock(oom_lock)
out_of_memory
select_bad_process
oom_kill_process(current)
wake_oom_reaper
oom_reap_task
MMF_OOM_SKIP->victim
mutex_unlock(oom_lock)
out_of_memory
select_bad_process # no task
If Thread1 didn't race it would bail out from try_charge and force the
charge. We can achieve the same by checking tsk_is_oom_victim inside
the oom_lock and therefore close the race.
[1] http://lkml.kernel.org/r/bb2074c0-34fe-8c2c-1c7d-db71338f1e7f@i-love.sakura.ne.jp
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
mm/memcontrol.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index af7f18b32389..90eb2e2093e7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1387,10 +1387,22 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
.gfp_mask = gfp_mask,
.order = order,
};
- bool ret;
+ bool ret = true;
mutex_lock(&oom_lock);
+
+ /*
+ * multi-threaded tasks might race with oom_reaper and gain
+ * MMF_OOM_SKIP before reaching out_of_memory which can lead
+ * to out_of_memory failure if the task is the last one in
+ * memcg which would be a false possitive failure reported
+ */
+ if (tsk_is_oom_victim(current))
+ goto unlock;
+
ret = out_of_memory(&oc);
+
+unlock:
mutex_unlock(&oom_lock);
return ret;
}
--
2.20.1
next prev parent reply other threads:[~2019-01-07 14:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-07 14:38 [PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko
2019-01-07 14:38 ` [PATCH 1/2] mm, oom: marks all killed tasks as oom victims Michal Hocko
2019-01-07 20:58 ` Tetsuo Handa
2019-01-08 8:11 ` Michal Hocko
2019-01-07 14:38 ` Michal Hocko [this message]
2019-01-07 20:59 ` [PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Tetsuo Handa
2019-01-08 8:14 ` Michal Hocko
2019-01-08 10:39 ` Tetsuo Handa
2019-01-08 11:46 ` Michal Hocko
2019-01-08 8:35 ` kbuild test robot
2019-01-08 9:39 ` Michal Hocko
2019-01-11 0:23 ` [kbuild-all] " Rong Chen
2019-01-08 14:21 ` [PATCH 3/2] memcg: Facilitate termination of memcg OOM victims Tetsuo Handa
2019-01-08 14:38 ` Michal Hocko
2019-01-09 11:03 ` [PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko
2019-01-09 11:34 ` Tetsuo Handa
2019-01-09 12:02 ` Michal Hocko
2019-01-10 23:59 ` Tetsuo Handa
2019-01-11 10:25 ` Tetsuo Handa
2019-01-11 11:33 ` Michal Hocko
2019-01-11 12:40 ` Tetsuo Handa
2019-01-11 13:34 ` Michal Hocko
2019-01-11 14:31 ` Tetsuo Handa
2019-01-11 15:07 ` Michal Hocko
2019-01-11 15:37 ` Tetsuo Handa
2019-01-11 16:45 ` Michal Hocko
2019-01-12 10:52 ` Tetsuo Handa
2019-01-13 17:36 ` Michal Hocko
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