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Date: Sat, 1 May 2010 20:56:18 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
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To: Mel Gorman <mel@csn.ul.ie>
cc: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>,
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       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Andrea Arcangeli <aarcange@redhat.com>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 2/2] mm,migration: Avoid race between shift_arg_pages()
 and rmap_walk() during migration by not migrating temporary stacks
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On Thu, 29 Apr 2010, Mel Gorman wrote:

> There is a race between shift_arg_pages and migration that triggers this bug.
> A temporary stack is setup during exec and later moved. If migration moves
> a page in the temporary stack and the VMA is then removed before migration
> completes, the migration PTE may not be found leading to a BUG when the
> stack is faulted.

A simpler solution would be to not allow migration of the temporary stack?