linux-kernel - Re: [PATCH 1/2] oom: do not live lock on frozen tasks

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Message-ID: <87sjnjk36l.fsf@rustcorp.com.au>
Date:	Mon, 26 Sep 2011 19:58:50 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Michal Hocko <mhocko@...e.cz>, David Rientjes <rientjes@...gle.com>
Cc:	Oleg Nesterov <oleg@...hat.com>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/2] oom: do not live lock on frozen tasks

On Mon, 26 Sep 2011 10:28:37 +0200, Michal Hocko <mhocko@...e.cz> wrote:
> On Fri 26-08-11 11:13:40, David Rientjes wrote:
> > I'd love to be able to do a thaw on a PF_FROZEN task in the oom killer 
> > followed by a SIGKILL if that task is selected for oom kill without an 
> > heuristic change.  Not sure if that's possible, so we'll wait for Rafael 
> > to chime in.
> 
> We have discussed that with Rafael and it should be safe to do that. See
> the patch bellow.
> The only place I am not entirely sure about is run_guest
> (drivers/lguest/core.c). It seems that the code is able to cope with
> signals but it also calls lguest_arch_run_guest after try_to_freeze.

Yes; if you want to kill things in the refrigerator(), then will a

		if (cpu->lg->dead || task_is_dead(current))
                        break;

Work?  That break means we return to the read() syscall pretty much
immediately.

Thanks for the CC,
Rusty.
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