From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Jens Axboe <jens.axboe@oracle.com>,
paulmck@linux.vnet.ibm.com, Ingo Molnar <mingo@elte.hu>,
Vegard Nossum <vegard.nossum@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Christoph Lameter <clameter@sgi.com>
Subject: Re: kmemcheck caught read from freed memory (cfq_free_io_context)
Date: Wed, 02 Apr 2008 13:14:09 +0200 [thread overview]
Message-ID: <1207134849.8514.775.camel@twins> (raw)
In-Reply-To: <84144f020804020411m7c6b0f27w16e8c6500867f3c1@mail.gmail.com>
On Wed, 2008-04-02 at 14:11 +0300, Pekka Enberg wrote:
> On Wed, 2008-04-02 at 13:07 +0200, Jens Axboe wrote:
> > > Makes sense, and to me Pauls analysis of the code looks totally correct
> > > - there's no bug there, at least related to hlist traversal and
> > > kmem_cache_free(), since we are under rcu_read_lock() and thus hold off
> > > the grace for freeing.
>
> On Wed, Apr 2, 2008 at 2:08 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > but what holds off the slab allocator re-issueing that same object and
> > someone else writing other stuff into it?
>
> Nothing. So you cannot access the object at all after you've called
> kmem_cache_free(). SLAB_RCU or no SLAB_RCU.
Well, you can, but you have to validate you get the object you were
looking for.
next prev parent reply other threads:[~2008-04-02 11:14 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-01 21:08 kmemcheck caught read from freed memory (cfq_free_io_context) Vegard Nossum
2008-04-01 21:36 ` Peter Zijlstra
2008-04-01 22:51 ` Paul E. McKenney
2008-04-02 6:15 ` Peter Zijlstra
2008-04-02 7:19 ` Jens Axboe
2008-04-02 10:24 ` Paul E. McKenney
2008-04-02 7:17 ` Jens Axboe
2008-04-02 7:20 ` Pekka J Enberg
2008-04-02 7:24 ` Jens Axboe
2008-04-02 7:28 ` Ingo Molnar
2008-04-02 7:31 ` Jens Axboe
2008-04-02 10:55 ` Paul E. McKenney
2008-04-02 10:59 ` Peter Zijlstra
2008-04-02 11:33 ` Fabio Checconi
2008-04-02 11:43 ` Jens Axboe
2008-04-02 12:36 ` Jens Axboe
2008-04-02 12:36 ` Jens Axboe
2008-04-02 12:55 ` Fabio Checconi
2008-04-02 12:58 ` Jens Axboe
2008-04-02 12:58 ` Jens Axboe
2008-04-02 13:16 ` Fabio Checconi
2008-04-02 16:14 ` Paul E. McKenney
2008-04-02 13:37 ` Paul E. McKenney
2008-04-02 13:41 ` Jens Axboe
2008-04-02 15:33 ` Paul E. McKenney
2008-04-02 16:31 ` Jens Axboe
2008-04-02 17:00 ` Paul E. McKenney
2008-04-02 13:32 ` Paul E. McKenney
2008-04-02 13:40 ` Jens Axboe
2008-04-02 16:15 ` Paul E. McKenney
2008-04-02 11:01 ` Pekka Enberg
2008-04-02 11:07 ` Jens Axboe
2008-04-02 11:08 ` Peter Zijlstra
2008-04-02 11:11 ` Pekka Enberg
2008-04-02 11:14 ` Peter Zijlstra [this message]
2008-04-02 11:18 ` Pekka Enberg
2008-04-02 17:36 ` Christoph Lameter
2008-04-02 11:14 ` Jens Axboe
2008-04-02 11:20 ` Peter Zijlstra
2008-04-02 11:25 ` Peter Zijlstra
2008-04-02 11:32 ` Jens Axboe
2008-04-02 11:37 ` Peter Zijlstra
2008-04-02 11:42 ` Jens Axboe
2008-04-02 11:47 ` Peter Zijlstra
2008-04-02 11:53 ` Jens Axboe
2008-04-02 12:13 ` Peter Zijlstra
2008-04-02 12:28 ` Jens Axboe
2008-04-02 13:26 ` Paul E. McKenney
2008-04-02 13:43 ` Andi Kleen
2008-04-02 12:26 ` Peter Zijlstra
2008-04-02 12:34 ` Jens Axboe
2008-04-02 16:08 ` Paul E. McKenney
2008-04-02 16:15 ` Vegard Nossum
2008-04-02 16:32 ` Pekka J Enberg
2008-04-02 18:23 ` Paul E. McKenney
2008-04-02 19:53 ` Pekka Enberg
2008-04-02 20:15 ` Paul E. McKenney
2008-04-03 15:18 ` Paul E. McKenney
2008-04-03 19:49 ` Pekka J Enberg
2008-04-03 21:27 ` Paul E. McKenney
2008-04-02 16:59 ` Paul E. McKenney
2008-04-02 17:31 ` Vegard Nossum
2008-04-02 10:40 ` Paul E. McKenney
2008-04-02 10:46 ` Pekka Enberg
2008-04-02 10:49 ` Peter Zijlstra
2008-04-02 10:54 ` Pekka J Enberg
2008-04-02 17:35 ` Christoph Lameter
2008-04-02 10:53 ` Peter Zijlstra
2008-04-02 11:13 ` Jens Axboe
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