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From: Michal Hocko <mhocko@kernel.org>
To: <linux-mm@kvack.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	David Rientjes <rientjes@google.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Vladimir Davydov <vdavydov@parallels.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks
Date: Mon, 20 Jun 2016 14:43:46 +0200	[thread overview]
Message-ID: <1466426628-15074-9-git-send-email-mhocko@kernel.org> (raw)
In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

0-day robot has encountered the following:
[   82.694232] Out of memory: Kill process 3914 (trinity-c0) score 167 or sacrifice child
[   82.695110] Killed process 3914 (trinity-c0) total-vm:55864kB, anon-rss:1512kB, file-rss:1088kB, shmem-rss:25616kB
[   82.706724] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26488kB
[   82.715540] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26900kB
[   82.717662] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26900kB
[   82.725804] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:27296kB
[   82.739091] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:28148kB

oom_reaper is trying to reap the same task again and again. This
is possible only when the oom killer is bypassed because of
task_will_free_mem because we skip over tasks with MMF_OOM_REAPED
already set during select_bad_process. Teach task_will_free_mem to skip
over MMF_OOM_REAPED tasks as well because they will be unlikely to free
anything more.

Analyzed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/oom_kill.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 8ee92fb76968..36d5dd88d990 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -747,6 +747,16 @@ bool task_will_free_mem(struct task_struct *task)
 		return false;
 
 	mm = p->mm;
+
+	/*
+	 * This task has already been drained by the oom reaper so there are
+	 * only small chances it will free some more
+	 */
+	if (test_bit(MMF_OOM_REAPED, &mm->flags)) {
+		task_unlock(p);
+		return false;
+	}
+
 	if (atomic_read(&mm->mm_users) <= 1) {
 		task_unlock(p);
 		return true;
-- 
2.8.1

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	David Rientjes <rientjes@google.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Vladimir Davydov <vdavydov@parallels.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks
Date: Mon, 20 Jun 2016 14:43:46 +0200	[thread overview]
Message-ID: <1466426628-15074-9-git-send-email-mhocko@kernel.org> (raw)
In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

0-day robot has encountered the following:
[   82.694232] Out of memory: Kill process 3914 (trinity-c0) score 167 or sacrifice child
[   82.695110] Killed process 3914 (trinity-c0) total-vm:55864kB, anon-rss:1512kB, file-rss:1088kB, shmem-rss:25616kB
[   82.706724] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26488kB
[   82.715540] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26900kB
[   82.717662] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:26900kB
[   82.725804] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:27296kB
[   82.739091] oom_reaper: reaped process 3914 (trinity-c0), now anon-rss:0kB, file-rss:0kB, shmem-rss:28148kB

oom_reaper is trying to reap the same task again and again. This
is possible only when the oom killer is bypassed because of
task_will_free_mem because we skip over tasks with MMF_OOM_REAPED
already set during select_bad_process. Teach task_will_free_mem to skip
over MMF_OOM_REAPED tasks as well because they will be unlikely to free
anything more.

Analyzed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/oom_kill.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 8ee92fb76968..36d5dd88d990 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -747,6 +747,16 @@ bool task_will_free_mem(struct task_struct *task)
 		return false;
 
 	mm = p->mm;
+
+	/*
+	 * This task has already been drained by the oom reaper so there are
+	 * only small chances it will free some more
+	 */
+	if (test_bit(MMF_OOM_REAPED, &mm->flags)) {
+		task_unlock(p);
+		return false;
+	}
+
 	if (atomic_read(&mm->mm_users) <= 1) {
 		task_unlock(p);
 		return true;
-- 
2.8.1

--
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  parent reply	other threads:[~2016-06-20 12:44 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-20 12:43 [PATCH 0/10 -v5] Handle oom bypass more gracefully Michal Hocko
2016-06-20 12:43 ` Michal Hocko
2016-06-20 12:43 ` [PATCH 01/10] proc, oom: drop bogus task_lock and mm check Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 02/10] proc, oom: drop bogus sighand lock Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 03/10] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 04/10] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 05/10] mm, oom: skip vforked tasks from being selected Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 06/10] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 07/10] mm, oom: fortify task_will_free_mem Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` Michal Hocko [this message]
2016-06-20 12:43   ` [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-20 12:43 ` [PATCH 09/10] mm, oom_reaper: do not attempt to reap a task more than twice Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-06-20 12:43 ` [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init Michal Hocko
2016-06-20 12:43   ` Michal Hocko
2016-07-19 12:05   ` Michal Hocko
2016-07-19 12:05     ` Michal Hocko
2016-07-19 23:27     ` Andrew Morton
2016-07-19 23:27       ` Andrew Morton
2016-07-20  6:29       ` Michal Hocko
2016-07-20  6:29         ` Michal Hocko
  -- strict thread matches above, loose matches on Subject: below --
2016-06-09 11:52 [PATCH 0/10 -v4] Handle oom bypass more gracefully Michal Hocko
2016-06-09 11:52 ` [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-09 11:52   ` Michal Hocko
2016-06-17 11:35   ` Tetsuo Handa
2016-06-17 11:35     ` Tetsuo Handa
2016-06-17 12:56     ` Michal Hocko
2016-06-17 12:56       ` Michal Hocko
2016-06-03  9:16 [PATCH 0/10 -v3] Handle oom bypass more gracefully Michal Hocko
2016-06-03  9:16 ` [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-03  9:16   ` Michal Hocko

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