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Date: Fri, 19 Oct 2012 02:28:42 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
Subject: Re: [patch for-3.7 v3] mm, mempolicy: hold task->mempolicy refcount
 while reading numa_maps.
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To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Dave Jones <davej@redhat.com>, KOSAKI Motohiro <kosaki.motohiro@gmail.com>, bhutchings@solarflare.com, Konstantin Khlebnikov <khlebnikov@openvz.org>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On Fri, 19 Oct 2012, Kamezawa Hiroyuki wrote:

> From c5849c9034abeec3f26bf30dadccd393b0c5c25e Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Date: Fri, 19 Oct 2012 17:00:55 +0900
> Subject: [PATCH] hold task->mempolicy while numa_maps scans.
> 
>  /proc/<pid>/numa_maps scans vma and show mempolicy under
>  mmap_sem. It sometimes accesses task->mempolicy which can
>  be freed without mmap_sem and numa_maps can show some
>  garbage while scanning.
> 
> This patch tries to take reference count of task->mempolicy at reading
> numa_maps before calling get_vma_policy(). By this, task->mempolicy
> will not be freed until numa_maps reaches its end.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Looks good, but the patch is whitespace damaged so it doesn't apply.  When 
that's fixed:

Acked-by: David Rientjes <rientjes@google.com>

Thanks for following through on this!

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