From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 4/9] oom: oom_kill_process() need to check p is unkillable
Cc: kosaki.motohiro@jp.fujitsu.com, LKML <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Minchan Kim <minchan.kim@gmail.com>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <alpine.DEB.2.00.1006211301110.8367@chino.kir.corp.google.com>
References: <20100617135224.FBAA.A69D9226@jp.fujitsu.com> <alpine.DEB.2.00.1006211301110.8367@chino.kir.corp.google.com>
Message-Id: <20100624211415.802E.A69D9226@jp.fujitsu.com>
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Date: Wed, 30 Jun 2010 18:26:19 +0900 (JST)
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> On Mon, 21 Jun 2010, KOSAKI Motohiro wrote:
> 
> > > > When oom_kill_allocating_task is enabled, an argument task of
> > > > oom_kill_process is not selected by select_bad_process(), It's
> > > > just out_of_memory() caller task. It mean the task can be
> > > > unkillable. check it first.
> > > > 
> > > 
> > > This should be unnecessary if oom_kill_process() appropriately returns 
> > > non-zero when it cannot kill a task.  What problem are you addressing with 
> > > this fix?
> > 
> > oom_kill_process() only check its children are unkillable, not its own.
> 
> No, oom_kill_process() returns the value of oom_kill_task(victim) which is 
> non-zero for !victim->mm in mmotm-2010-06-11-16-40 (and 2.6.34 although 
> victim == p in that case).

oom_kill_task() only check OOM_DISABLE. and Minchan elaborated more detailed
concern. please see his mail.


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