Re: [PATCH 01/12] mm,migration: Take a reference to the anon_vmabefore migrating

From: Rik van Riel
Date: Fri Feb 19 2010 - 11:44:24 EST


On 02/18/2010 01:02 PM, Mel Gorman wrote:
rmap_walk_anon() does not use page_lock_anon_vma() for looking up and
locking an anon_vma and it does not appear to have sufficient locking to
ensure the anon_vma does not disappear from under it.

This patch copies an approach used by KSM to take a reference on the
anon_vma while pages are being migrated. This should prevent rmap_walk()
running into nasty surprises later because anon_vma has been freed.

Signed-off-by: Mel Gorman<mel@xxxxxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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