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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
	Mel Gorman <mgorman@suse.de>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Oleg Nesterov <oleg@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	Andrea Argangeli <andrea@kernel.org>,
	Rik van Riel <riel@redhat.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 6/5] oom, oom_reaper: disable oom_reaper for
Date: Wed, 17 Feb 2016 10:48:55 +0100	[thread overview]
Message-ID: <20160217094855.GC29196@dhcp22.suse.cz> (raw)
In-Reply-To: <1454505240-23446-6-git-send-email-mhocko@kernel.org>

Hi Andrew,
although this can be folded into patch 5
(mm-oom_reaper-implement-oom-victims-queuing.patch) I think it would be
better to have it separate and revert after we sort out the proper
oom_kill_allocating_task behavior or handle exclusion at oom_reaper
level.

Thanks!
---
>From 7d8c953994f97fb38a8d71b53c06ecf8418616e9 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Wed, 17 Feb 2016 10:40:41 +0100
Subject: [PATCH] oom, oom_reaper: disable oom_reaper for
 oom_kill_allocating_task

Tetsuo has reported that oom_kill_allocating_task=1 will cause
oom_reaper_list corruption because oom_kill_process doesn't follow
standard OOM exclusion (aka ignores TIF_MEMDIE) and allows to enqueue
the same task multiple times - e.g. by sacrificing the same child
multiple times. Let's workaround this issue for now until we decide
how to handle oom_kill_allocating_task properly (should it sacrifice
children at all?) or come up with some other protection.

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/oom_kill.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7e9953a64489..078e07ec0906 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -678,7 +678,14 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
 	unsigned int victim_points = 0;
 	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
 					      DEFAULT_RATELIMIT_BURST);
-	bool can_oom_reap = true;
+	bool can_oom_reap;
+
+	/*
+	 * XXX: oom_kill_allocating_task doesn't follow normal OOM exclusion
+	 * and so the same task might enter oom_kill_process which oom_reaper
+	 * cannot handle currently.
+	 */
+	can_oom_reap = !sysctl_oom_kill_allocating_task;
 
 	/*
 	 * If the task is already exiting, don't alarm the sysadmin or kill
-- 
2.7.0

-- 
Michal Hocko
SUSE Labs

  parent reply	other threads:[~2016-02-17  9:49 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 13:13 [PATCH 0/5] oom reaper v5 Michal Hocko
2016-02-03 13:13 ` [PATCH 1/5] mm, oom: introduce oom reaper Michal Hocko
2016-02-03 23:48   ` David Rientjes
2016-02-04  6:41     ` Michal Hocko
2016-02-06 13:22   ` Tetsuo Handa
2016-02-15 20:50     ` Michal Hocko
2016-02-03 13:13 ` [PATCH 2/5] oom reaper: handle mlocked pages Michal Hocko
2016-02-03 23:57   ` David Rientjes
2016-02-23  1:36   ` David Rientjes
2016-02-23 13:21     ` Michal Hocko
2016-02-29  3:19       ` Hugh Dickins
2016-02-29 13:41         ` Michal Hocko
2016-03-08 13:40           ` Michal Hocko
2016-03-08 20:07             ` Hugh Dickins
2016-03-09  8:26               ` Michal Hocko
2016-02-03 13:13 ` [PATCH 3/5] oom: clear TIF_MEMDIE after oom_reaper managed to unmap the address space Michal Hocko
2016-02-04 14:22   ` Tetsuo Handa
2016-02-04 14:43     ` Michal Hocko
2016-02-04 15:08       ` Tetsuo Handa
2016-02-04 16:31         ` Michal Hocko
2016-02-05 11:14           ` Tetsuo Handa
2016-02-06  8:30             ` Michal Hocko
2016-02-06 11:23               ` Tetsuo Handa
2016-02-15 20:47                 ` Michal Hocko
2016-02-06  6:45       ` Michal Hocko
2016-02-06 14:33         ` Tetsuo Handa
2016-02-15 20:40           ` [PATCH 3.1/5] oom: make oom_reaper freezable Michal Hocko
2016-02-03 13:13 ` [PATCH 4/5] mm, oom_reaper: report success/failure Michal Hocko
2016-02-03 23:10   ` David Rientjes
2016-02-04  6:46     ` Michal Hocko
2016-02-04 22:31       ` David Rientjes
2016-02-05  9:26         ` Michal Hocko
2016-02-06  6:34           ` Michal Hocko
2016-02-03 13:14 ` [PATCH 5/5] mm, oom_reaper: implement OOM victims queuing Michal Hocko
2016-02-04 10:49   ` Tetsuo Handa
2016-02-04 14:53     ` Michal Hocko
2016-02-06  5:54       ` Tetsuo Handa
2016-02-06  8:37         ` Michal Hocko
2016-02-06 15:33           ` Tetsuo Handa
2016-02-15 20:15             ` Michal Hocko
2016-02-16 11:11               ` Tetsuo Handa
2016-02-16 15:53                 ` Michal Hocko
2016-02-17  9:48   ` Michal Hocko [this message]
2016-02-17 10:41     ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for Tetsuo Handa
2016-02-17 11:33       ` Michal Hocko
2016-02-19 18:34     ` Michal Hocko
2016-02-20  2:32       ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task Tetsuo Handa
2016-02-22  9:41         ` Michal Hocko

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