From: David Rientjes <rientjes@google.com>
To: David Mackey <tdmackey@twitter.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andi Kleen <ak@linux.intel.com>,
penberg@kernel.org, cl@linux.com
Subject: Re: [PATCH v4] slab/mempolicy: always use local policy from interrupt context
Date: Thu, 31 May 2012 13:41:29 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1205311340170.2764@chino.kir.corp.google.com> (raw)
In-Reply-To: <1338429749-5780-1-git-send-email-tdmackey@twitter.com>
On Wed, 30 May 2012, David Mackey wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> slab_node() could access current->mempolicy from interrupt context.
> However there's a race condition during exit where the mempolicy
> is first freed and then the pointer zeroed.
>
> Using this from interrupts seems bogus anyways. The interrupt
> will interrupt a random process and therefore get a random
> mempolicy. Many times, this will be idle's, which noone can change.
>
> Just disable this here and always use local for slab
> from interrupts. I also cleaned up the callers of slab_node a bit
> which always passed the same argument.
>
> I believe the original mempolicy code did that in fact,
> so it's likely a regression.
>
> v2: send version with correct logic
> v3: simplify. fix typo.
> Reported-by: Arun Sharma <asharma@fb.com>
> Cc: penberg@kernel.org
> Cc: cl@linux.com
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> [tdmackey@twitter.com: Rework patch logic and avoid dereference of current
> task if in interrupt context.]
> Signed-off-by: David Mackey <tdmackey@twitter.com>
Acked-by: David Rientjes <rientjes@google.com>
Thanks for following up on this.
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prev parent reply other threads:[~2012-05-31 20:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1336431315-29736-1-git-send-email-andi@firstfloor.org>
2012-05-31 2:02 ` David Mackey
2012-05-31 4:22 ` Andi Kleen
2012-05-31 4:59 ` KOSAKI Motohiro
2012-05-31 7:50 ` Pekka Enberg
2012-05-31 20:41 ` David Rientjes [this message]
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