On Mon, Jul 09, 2012 at 11:42:12AM +0900, Kamezawa Hiroyuki wrote:
> (2012/07/05 9:44), Johannes Weiner wrote:
> > @@ -3278,10 +3283,11 @@ void mem_cgroup_end_migration(struct mem_cgroup
> > *memcg,
> > unused = oldpage;
> > }
> > anon = PageAnon(used);
> > - __mem_cgroup_uncharge_common(unused,
> > - anon ? MEM_CGROUP_CHARGE_TYPE_ANON
> > - : MEM_CGROUP_CHARGE_TYPE_CACHE,
> > - true);
> > + if (!PageSwapCache(page))
> > + __mem_cgroup_uncharge_common(unused,
> > + anon ? MEM_CGROUP_CHARGE_TYPE_ANON
> > + : MEM_CGROUP_CHARGE_TYPE_CACHE,
> > + true);
>
> !PageSwapCache(unused) ?
Argh, right.
> But I think unused page's PG_swapcache is always dropped. So, the check is
> not necessary.
Oh, this is intentional: the check was in __mem_cgroup_uncharge_common
before, which means it applied to this entry point as well. This is
supposed to be a mechanical change that does not change any logic.
The check is then removed in the next patch.
---
Subject: mm: memcg: push down PageSwapCache check into uncharge entry functions
fix
Signed-off-by: Johannes Weiner <han...@cmpxchg.org>
---
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a3bf414..f4ff18a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3283,7 +3283,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg,
unused = oldpage;
}
anon = PageAnon(used);
- if (!PageSwapCache(page))
+ if (!PageSwapCache(unused))
__mem_cgroup_uncharge_common(unused,
anon ? MEM_CGROUP_CHARGE_TYPE_ANON
: MEM_CGROUP_CHARGE_TYPE_CACHE,
--
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