Re: [patch for-3.7 v3] mm, mempolicy: hold task->mempolicy refcountwhile reading numa_maps.

From: David Rientjes
Date: Fri Oct 19 2012 - 05:28:36 EST

On Fri, 19 Oct 2012, Kamezawa Hiroyuki wrote:

> From c5849c9034abeec3f26bf30dadccd393b0c5c25e Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> 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@xxxxxxxxxxxxxx>

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

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>

Thanks for following through on this!
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