linux-kernel - Re: kmemcheck caught read from freed memory (cfq_free_io

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Message-ID: <84144f020804020346v6c6de91fr795dec55e0543105@mail.gmail.com>
Date:	Wed, 2 Apr 2008 13:46:39 +0300
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	paulmck@...ux.vnet.ibm.com
Cc:	"Jens Axboe" <jens.axboe@...cle.com>,
	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
	"Vegard Nossum" <vegard.nossum@...il.com>,
	"Ingo Molnar" <mingo@...e.hu>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	"Christoph Lameter" <clameter@....com>
Subject: Re: kmemcheck caught read from freed memory (cfq_free_io_context)

Hi Paul,

On Wed, Apr 2, 2008 at 1:40 PM, Paul E. McKenney
<paulmck@...ux.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
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