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

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Message-ID: <20110930080445.GC32134@tiehlicka.suse.cz>
Date:	Fri, 30 Sep 2011 10:04:45 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Tejun Heo <htejun@...il.com>
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

On Fri 30-09-11 00:46:41, Tejun Heo wrote:
> Hello,
> 
> On Fri, Sep 30, 2011 at 09:41:25AM +0200, Michal Hocko wrote:
> > > 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().  
> > 
> > Will the rework help with the initial problem of unkillable OOM selected
> > frozen tasks or it will just help with other races that might be present
> > with the patch? In other words will this work deprecate the 2 patches
> > sent earlier in this thread?
> 
> I think it shouldn't be difficult to allow OOM-killing frozen tasks.
> That should be good enough, right?

Yes, if you could just force_sig(SIGKILL, p) frozen task then it would
be ideal because we wouldn't have to call thaw_process from OOM path.

> 
> > > How urgent is this?  Can we wait for the next merge window?
> > 
> > Yes, I think we can wait some more.
> 
> I'm still processing rather large backlog.  I'll ping you back once I
> sort out the pending freezer changes.

You were on the CC quite early but it was quite late when I noticed that
I have accidentally used your kernel.org address. Just for reference the
original discussion started here: https://lkml.org/lkml/2011/8/23/45 and
this thread started here:
http://www.spinics.net/lists/linux-mm/msg24693.html

> 
> Thanks.
> 
> -- 
> tejun
> 
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-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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