Date: Thu, 12 Jun 2008 02:08:46 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>,
       Manfred Spraul <manfred@colorfullife.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: repeatable slab corruption with LTP msgctl08
Message-Id: <20080612020846.c77761cd.akpm@linux-foundation.org>
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On Thu, 12 Jun 2008 10:35:55 +0200 Andi Kleen <andi@firstfloor.org> wrote:

> Andrew Morton <akpm@linux-foundation.org> writes:
> >
> > Doing the same thing on 2.6.26-rc5-mm3, msgctl08 also runs to
> > completion, in 20.9 seconds.  So
> >
> > - it got slower
> 
> That is because it scales itself to the number of available msg queues.
> So with Nadia's patch there are more and it runs slower.
> 
> In fact it seems to start one process per message queue, so perhaps it's 
> just running out of processes or something. Ok it should not segfault.
> 
> BTW a great way to debug slab corruptions with LTP faster is to run with
> a slab thrasher stress module like http://firstfloor.org/~andi/crasher-26.diff
> 

Something like that might be needed.  I ran it again and it took 49
minutes to crash.

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