linux-kernel - Re: [patch] oom: thaw threads if oom killed thread is frozen before deferring

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Message-ID: <20110930015148.GD10425@mtj.dyndns.org>
Date:	Thu, 29 Sep 2011 18:51:48 -0700
From:	Tejun Heo <htejun@...il.com>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	Oleg Nesterov <oleg@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch] oom: thaw threads if oom killed thread is frozen before
 deferring

Hello,

On Thu, Sep 29, 2011 at 08:00:21PM +0200, Michal Hocko wrote:
> > I meant, oom_kill can do this before thaw thaw_process(), afaics
> > this should fix the particular race you described (but not others).
> 
> This is what the follow up fix from David is doing. Check frozen in
> select_bad_process if the task is TIF_MEMDIE and thaw the process.
> 
> And it seems that the David's follow up fix is sufficient so let's leave
> refrigerator alone.
> Or am I still missing something?

With pending freezer changes, allowing TIF_MEMDIE tasks to exit
freezer by modifying freezing() shouldn't be difficult, which should
be race-free and much simpler than diddling with thaw_task().  How
urgent is this?  Can we wait for the next merge window?

Thanks.

-- 
tejun
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