linux-kernel - Re: OOM kernel behaviour

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Date:	Wed, 2 Dec 2009 15:55:38 +0000
From:	Mel Gorman <mel@....ul.ie>
To:	Christoph Lameter <cl@...ux-foundation.org>
Cc:	David John <davidjon@...ontk.org>, linux-kernel@...r.kernel.org,
	Jonathan Miles <jon@...us.co.uk>,
	Pekka Enberg <penberg@...helsinki.fi>
Subject: Re: OOM kernel behaviour

On Tue, Dec 01, 2009 at 11:26:37AM -0600, Christoph Lameter wrote:
> On Tue, 1 Dec 2009, David John wrote:
> 
> > Here are three logs from three days. Log3.txt is today's log and the OOM
> > killer murdered Thunderbird as I was attempting to write this message.
> > The kernel config is also attached.
> 
> Hmmm... This is all caused by the HIGHMEM zone freecount going beyond min
> which then triggers reclaim which for some reason fails (should not there
> is sufficient material there to reclaim). There is enough memory in the
> NORMAL zone. Wonder if something broke in 2.6.31 in reclaim? Mel?
> 

I'm not aware of breakage of that level, nor do I believe the page
allocator problems are related to this bug.

However, I just took a look at the logs from the three days and I see
things like

Nov 25 23:58:53 avalanche kernel: Free swap  = 0kB
Nov 25 23:58:53 avalanche kernel: Total swap = 2048248kB


Something on that system is leaking badly. Do something like

ps aux --sort vsz

and see what process has gone mental and is consuming all of swap. It's
possible that the OOM killer is triggering too easily but it's possible
that a delayed triggering of the OOM killer would have been just that -
a delay. Eventually all memory and all swap would be used.

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