Re: [BUGFIX][PATCH] memcg: fix memory migration of shmem swapcache

From: KAMEZAWA Hiroyuki
Date: Wed Jan 05 2011 - 21:01:35 EST

On Thu, 6 Jan 2011 10:09:23 +0900
Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:

> ===
> From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> In current implimentation, mem_cgroup_end_migration() decides whether the page
> migration has succeeded or not by checking "oldpage->mapping".
> But if we are tring to migrate a shmem swapcache, the page->mapping of it is
> NULL from the begining, so the check would be invalid.
> As a result, mem_cgroup_end_migration() assumes the migration has succeeded
> even if it's not, so "newpage" would be freed while it's not uncharged.
> This patch fixes it by passing mem_cgroup_end_migration() the result of the
> page migration.
> Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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