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Date: Wed, 2 Apr 2008 13:46:39 +0300
From: "Pekka Enberg" <penberg@cs.helsinki.fi>
To: paulmck@linux.vnet.ibm.com
Subject: Re: kmemcheck caught read from freed memory (cfq_free_io_context)
Cc: "Jens Axboe" <jens.axboe@oracle.com>,
       "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
       "Vegard Nossum" <vegard.nossum@gmail.com>,
       "Ingo Molnar" <mingo@elte.hu>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       "Christoph Lameter" <clameter@sgi.com>
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Hi Paul,

On Wed, Apr 2, 2008 at 1:40 PM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
>  I am still confused.
>
>  o       The kmem_cache has SLAB_DESTROY_BY_RCU.
>
>  o       This means that a given slab should not be returned to the
>         system until a grace period elapses.

Yeah, that's what I thought too, that this is a SLUB bug but Peter
convinced me otherwise. SLUB keeps the _page_ around so the pointer
will be _valid_, although it might not be _your_ pointer so the caller
needs to do some validation step. Or at least that's how I understood
what Peter was saying.

                      Pekka