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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@kernel.org, akpm@linux-foundation.org
Cc: linux-mm@kvack.org,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov@virtuozzo.com>
Subject: [PATCH] memcg: fix mem_cgroup_out_of_memory() return value.
Date: Fri, 20 May 2016 23:08:47 +0900
Message-ID: <1463753327-5170-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> (raw)

mem_cgroup_out_of_memory() is returning "true" if it finds a TIF_MEMDIE
task after an eligible task was found, "false" if it found a TIF_MEMDIE
task before an eligible task is found.

This difference confuses memory_max_write() which checks the return value
of mem_cgroup_out_of_memory(). Since memory_max_write() wants to continue
looping, mem_cgroup_out_of_memory() should return "true" in this case.

This patch sets a dummy pointer in order to return "true".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
---
 mm/memcontrol.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b3f16ab..ab574d8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1302,6 +1302,8 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 				mem_cgroup_iter_break(memcg, iter);
 				if (chosen)
 					put_task_struct(chosen);
+				/* Set a dummy value to return "true". */
+				chosen = (void *) 1;
 				goto unlock;
 			case OOM_SCAN_OK:
 				break;
-- 
1.8.3.1

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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-20 14:08 Tetsuo Handa [this message]
2016-05-20 15:09 ` Michal Hocko
2016-05-23 10:28 ` Vladimir Davydov

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