Date: Fri, 6 Nov 2009 09:24:47 +0000
From: Mel Gorman <mel@csn.ul.ie>
To: Tobias Diedrich <ranma+kernel@tdiedrich.de>, Frans Pop <elendil@planet.nl>,
       Jiri Kosina <jkosina@suse.cz>,
       Sven Geggus <lists@fuchsschwanzdomain.de>,
       Karol Lewandowski <karol.k.lewandowski@gmail.com>,
       Tobias Oetiker <tobi@oetiker.ch>, "Rafael J. Wysocki" <rjw@sisk.pl>,
       David Miller <davem@davemloft.net>,
       Reinette Chatre <reinette.chatre@intel.com>,
       Kalle Valo <kalle.valo@iki.fi>, David Rientjes <rientjes@google.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Mohamed Abbas <mohamed.abbas@intel.com>,
       Jens Axboe <jens.axboe@oracle.com>,
       "John W. Linville" <linville@tuxdriver.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>,
       Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>,
       Greg Kroah-Hartman <gregkh@suse.de>,
       Stephan von Krawczynski <skraw@ithnet.com>,
       Kernel Testers List <kernel-testers@vger.kernel.org>,
       netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
       "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 0/5] Candidate fix for increased number of GFP_ATOMIC
	failures V2
Message-ID: <20091106092447.GC25926@csn.ul.ie>
References: <1256221356-26049-1-git-send-email-mel@csn.ul.ie> <20091106060323.GA5528@yumi.tdiedrich.de>
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On Fri, Nov 06, 2009 at 07:03:23AM +0100, Tobias Diedrich wrote:
> Mel Gorman wrote:
> > [No BZ ID] Kernel crash on 2.6.31.x (kcryptd: page allocation failure..)
> > 	This apparently is easily reproducible, particular in comparison to
> > 	the other reports. The point of greatest interest is that this is
> > 	order-0 GFP_ATOMIC failures. Sven, I'm hoping that you in particular
> > 	will be able to follow the tests below as you are the most likely
> > 	person to have an easily reproducible situation.
> 
> I've also seen order-0 failures on 2.6.31.5:
> Note that this is with a one process hogging and mlocking memory and
> min_free_kbytes reduced to 100 to reproduce the problem more easily.
> 

Is that a vanilla, with patches 1-3 applied or both?

> I tried bisecting the issue, but in the end without memory pressure
> I can't reproduce it reliably and with the above mentioned pressure
> I get allocation failures even on 2.6.30.o
> 

To be honest, it's not entirely unexpected with min_free_kbytes set that
low. The system should cope with a certain amount of pressure but with
pressure and a low min_free_kbytes, the system will simply be reacting
too late to free memory in the non-atomic paths.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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