From: Michal Hocko <mhocko@kernel.org> To: <linux-mm@kvack.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, David Rientjes <rientjes@google.com>, Andrew Morton <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com> Subject: [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Date: Mon, 22 Oct 2018 09:13:23 +0200 [thread overview] Message-ID: <20181022071323.9550-3-mhocko@kernel.org> (raw) In-Reply-To: <20181022071323.9550-1-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 e79cb59552d9..a9dfed29967b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1380,10 +1380,22 @@ 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; } -- 2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: linux-mm@kvack.org Cc: Johannes Weiner <hannes@cmpxchg.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, David Rientjes <rientjes@google.com>, Andrew Morton <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com> Subject: [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Date: Mon, 22 Oct 2018 09:13:23 +0200 [thread overview] Message-ID: <20181022071323.9550-3-mhocko@kernel.org> (raw) In-Reply-To: <20181022071323.9550-1-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 e79cb59552d9..a9dfed29967b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1380,10 +1380,22 @@ 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; } -- 2.19.1
next prev parent reply other threads:[~2018-10-22 7:13 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-10-22 7:13 [RFC PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko 2018-10-22 7:13 ` Michal Hocko 2018-10-22 7:13 ` [RFC PATCH 1/2] mm, oom: marks all killed tasks as oom victims Michal Hocko 2018-10-22 7:13 ` Michal Hocko 2018-10-22 7:58 ` Tetsuo Handa 2018-10-22 8:48 ` Michal Hocko 2018-10-22 9:42 ` Tetsuo Handa 2018-10-22 10:43 ` Michal Hocko 2018-10-22 10:56 ` Tetsuo Handa 2018-10-22 11:12 ` Michal Hocko 2018-10-22 11:16 ` [RFC PATCH v2 " Michal Hocko 2018-10-22 11:16 ` Michal Hocko 2018-10-22 7:13 ` Michal Hocko [this message] 2018-10-22 7:13 ` [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Michal Hocko 2018-10-22 11:45 ` Tetsuo Handa 2018-10-22 12:03 ` Michal Hocko 2018-10-22 13:20 ` Tetsuo Handa 2018-10-22 13:43 ` Michal Hocko 2018-10-22 15:12 ` Tetsuo Handa 2018-10-23 1:01 ` Tetsuo Handa 2018-10-23 11:42 ` Michal Hocko 2018-10-23 12:10 ` Michal Hocko 2018-10-23 12:33 ` Tetsuo Handa 2018-10-23 12:48 ` Michal Hocko 2018-10-26 14:25 ` Johannes Weiner 2018-10-26 19:25 ` Michal Hocko 2018-10-26 19:33 ` Michal Hocko 2018-10-27 1:10 ` Tetsuo Handa 2018-11-06 9:44 ` Tetsuo Handa 2018-11-06 9:44 ` Tetsuo Handa 2018-11-06 12:42 ` Michal Hocko 2018-11-07 9:45 ` Tetsuo Handa 2018-11-07 10:08 ` Michal Hocko 2018-12-07 12:43 ` Tetsuo Handa 2018-12-12 10:23 ` Tetsuo Handa 2018-12-12 10:23 ` Tetsuo Handa
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