Date: Wed, 23 May 2007 10:10:20 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
To: Srihari Vijayaraghavan <sriharivijayaraghavan@yahoo.com.au>
cc: Hugh Dickins <hugh@veritas.com>, Ingo Molnar <mingo@elte.hu>,
       Oliver Xymoron <oxymoron@waste.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Jens Axboe <jens.axboe@oracle.com>, linux-kernel@vger.kernel.org
Subject: Re: [PROBLEM] 2.6.22-rc2 panics on x86-64 with slub
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On Wed, 23 May 2007, Srihari Vijayaraghavan wrote:

> > and then try to boot without slub_debug.
> 
> I guess you mean with CONFIG_SLUB_CONFIG=y? If so, I built another kernel with
> CONFIG_SLUB_DEBUG=y (plus all of the above) & tested it. It panics by default,
> but with slub_nomerge it works just fine (tested under moderate load).
> 
> (the panic message produced by CONFIG_SLUB_DEBUG=y was the exact same call
> trace as my very first email in this email thread with slightly different
> address on a couple of functions, but rest remains the same)

Ahh... At least we are getting to the original problem.
 
> I'm personally very happy that slub works stably without slub debug options,
> because that's what I'd run in a production env. Thanks to your patch, slub is
> quite stable without the slub debug for me :-)). But it'd to nice to have a
> working slub debug for test env., as you'd undoubtedly be aware of, of course
> :-). Just my humble opinion.
> 
> > If that fails then boot with slub_nomerge

So lockdep has issues with slab merging? If locks are tracking within 
slabs then I imagine that lockdep gets confused if we put them together.

> Yup, I had to use slub_nomerge; without that CONFIG_SLUB_DEBUG=y kernel
> panics. (I haven't tested the UP case though. I did try nosmp & maxcpus=1, but
> they had no effect on the panic. Do you want me to test UP case for
> CONFIG_SLUB_DEBUG=y without slub_nomerge?)

Yes.

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