[RFC][PATCH 5/6] memcg: remove unnecessary memory barrier.

[KAMEZAWA Hiroyuki]

Now, Used bit and a pointer to memory cgroup are set at once.
memory barrier for Used bit -> pc->mem_cgroup is not necessary.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
 mm/memcontrol.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 622fd2e..767bef3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1258,8 +1258,6 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 	pc = lookup_page_cgroup(page);
 	if (!PageCgroupUsed(pc))
 		return NULL;
-	/* Ensure pc's mem_cgroup is visible after reading PCG_USED. */
-	smp_rmb();
 	mz = page_cgroup_zoneinfo(pc_to_mem_cgroup(pc), page);
 	return &mz->reclaim_stat;
 }
-- 
1.7.4.1


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