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Date: Wed, 25 Nov 2009 09:39:33 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
       stable <stable@kernel.org>, David Rientjes <rientjes@google.com>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [BUGFIX][PATCH -mmotm] memcg: avoid oom-killing innocent task
	in case of use_hierarchy
Message-ID: <20091125040933.GE3365@balbir.in.ibm.com>
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* nishimura@mxp.nes.nec.co.jp <nishimura@mxp.nes.nec.co.jp> [2009-11-24 14:57:59]:

> task_in_mem_cgroup(), which is called by select_bad_process() to check whether
> a task can be a candidate for being oom-killed from memcg's limit, checks
> "curr->use_hierarchy"("curr" is the mem_cgroup the task belongs to).
> 
> But this check return true(it's false positive) when:
> 
> 	<some path>/00		use_hierarchy == 0	<- hitting limit
> 	  <some path>/00/aa	use_hierarchy == 1	<- "curr"
> 
> This leads to killing an innocent task in 00/aa. This patch is a fix for this
> bug. And this patch also fixes the arg for mem_cgroup_print_oom_info(). We
> should print information of mem_cgroup which the task being killed, not current,
> belongs to.
> 
> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>


Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
 
-- 
	Balbir
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