memcg: charged pages always have valid per-memcg zone info

page_cgroup_zoneinfo() will never return NULL for a charged page, remove
the check for it in mem_cgroup_get_reclaim_stat_from_page().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 660dfc2..b35a28d 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1043,9 +1043,6 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
        /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
        smp_rmb();
        mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
-       if (!mz)
-               return NULL;
-
        return &mz->reclaim_stat;
 }