Date: Fri, 9 Oct 2009 21:50:16 +0200
From: Robert Richter <robert.richter@amd.com>
To: Ingo Molnar <mingo@elte.hu>
CC: LKML <linux-kernel@vger.kernel.org>,
       oprofile-list <oprofile-list@lists.sourceforge.net>,
       David Rientjes <rientjes@google.com>,
       Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 1/2] oprofile: fix race condition in event_buffer free
Message-ID: <20091009195016.GH638@erda.amd.com>
References: <20091009160532.GD638@erda.amd.com>
 <1255116810-26514-1-git-send-email-robert.richter@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <1255116810-26514-1-git-send-email-robert.richter@amd.com>
User-Agent: Mutt/1.5.20 (2009-06-14)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1402
Lines: 40

On 09.10.09 21:33:29, Robert Richter wrote:
> From: David Rientjes <rientjes@google.com>
> 
> Looking at the 2.6.31-rc9 code, it appears there is a race condition
> in the event_buffer cleanup code path (shutdown). This could lead to
> kernel panic as some CPUs may be operating on the event buffer AFTER
> it has been freed. The attached patch solves the problem and makes
> sure CPUs check if the buffer is not NULL before they access it as
> some may have been spinning on the mutex while the buffer was being
> freed.
> 
> The race may happen if the buffer is freed during pending reads. But
> it is not clear why there are races in add_event_entry() since all
> workqueues or handlers are canceled or flushed before the event buffer
> is freed.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Signed-off-by: Robert Richter <robert.richter@amd.com>

Ingo,

you can also pull the patches from here:

 git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile.git urgent

Thanks.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center
email: robert.richter@amd.com

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/