linux-kernel - Re: system death under oom

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Date:	Sat, 6 Apr 2013 06:03:37 -0400
From:	Ilia Mirkin <imirkin@...m.mit.edu>
To:	Christoph Lameter <cl@...ux.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	nouveau@...ts.freedesktop.org, linux-mm@...ck.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: system death under oom - 3.7.9

On Sat, Apr 6, 2013 at 5:01 AM, Ilia Mirkin <imirkin@...m.mit.edu> wrote:
> On Mon, Apr 1, 2013 at 4:14 PM, Christoph Lameter <cl@...ux.com> wrote:
>> On Wed, 27 Mar 2013, Ilia Mirkin wrote:
>>
>>> The GPF happens at +160, which is in the argument setup for the
>>> cmpxchg in slab_alloc_node. I think it's the call to
>>> get_freepointer(). There was a similar bug report a while back,
>>> https://lkml.org/lkml/2011/5/23/199, and the recommendation was to run
>>> with slub debugging. Is that still the case, or is there a simpler
>>> explanation? I can't reproduce this at will, not sure how many times
>>> this has happened but definitely not many.
>>
>> slub debugging will help to track down the cause of the memory corruption.
>
> OK, with slub_debug=FZP, I get (after a while):
>
> http://pastebin.com/cbHiKhdq
>
> Which definitely makes it look like something in the nouveau
> context/whatever alloc failure path causes some stomping to happen. (I
> don't suppose it's reasonable to warn when the stomping happens
> through some sort of page protection... would explode the size since
> each n-byte object would be at least 4K, but might be worth it for
> debugging...)

OK, after staring for a while at this code, I found an issue, and
looks like it's already fixed by
cfd376b6bfccf33782a0748a9c70f7f752f8b869 (drm/nouveau/vm: fix memory
corruption when pgt allocation fails), which didn't make it into
3.7.9, but is in 3.7.10. Time to upgrade, I guess. Thanks for the
various suggestions.
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