linux-kernel - [BUGFIX][PATCH] memcg: fix oom killing a child process in an other cgroup

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Message-Id: <20100212105318.caf37133.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 12 Feb 2010 10:53:18 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, stable@...nel.org,
	minchan.kim@...il.com, rientjes@...gle.com,
	"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>
Subject: [BUGFIX][PATCH] memcg: fix oom killing a child process in an other
 cgroup

This patch itself is againt mmotm-Feb10 but can be applied to 2.6.32.8
without problem.

==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Now, oom-killer is memcg aware and it finds the worst process from
processes under memcg(s) in oom. Then, it kills victim's child at first.
It may kill a child in other cgroup and may not be any help for recovery.
And it will break the assumption users have...

This patch fixes it.

CC: stable@...nel.org
CC: Minchan Kim <minchan.kim@...il.com>
CC: Balbir Singh <balbir@...ux.vnet.ibm.com>
CC: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Acked-by: David Rientjes <rientjes@...gle.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

---
 mm/oom_kill.c |    2 ++
 1 file changed, 2 insertions(+)

Index: mmotm-2.6.33-Feb10/mm/oom_kill.c
===================================================================
--- mmotm-2.6.33-Feb10.orig/mm/oom_kill.c
+++ mmotm-2.6.33-Feb10/mm/oom_kill.c
@@ -459,6 +459,8 @@ static int oom_kill_process(struct task_
 	list_for_each_entry(c, &p->children, sibling) {
 		if (c->mm == p->mm)
 			continue;
+		if (mem && !task_in_mem_cgroup(c, mem))
+			continue;
 		if (!oom_kill_task(c))
 			return 0;
 	}

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