memcg: add mem_cgroup_zone_nr_pages()

Introduce mem_cgroup_zone_nr_pages().  It is called by zone_nr_pages()
helper function.

This patch doesn't have any behavior change.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -102,6 +102,9 @@ extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
 					int priority, enum lru_list lru);
 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg,
 				    struct zone *zone);
+unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
+				       struct zone *zone,
+				       enum lru_list lru);
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 extern int do_swap_account;
@@ -260,6 +263,14 @@ mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
 	return 1;
 }
 
+static inline unsigned long
+mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, struct zone *zone,
+			 enum lru_list lru)
+{
+	return 0;
+}
+
+
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
 #endif /* _LINUX_MEMCONTROL_H */

mm/memcontrol.c

@@ -186,7 +186,6 @@ pcg_default_flags[NR_CHARGE_TYPE] = {
 	0, /* FORCE */
 };
 
-
 /* for encoding cft->private value on file */
 #define _MEM			(0)
 #define _MEMSWAP		(1)
@@ -448,6 +447,17 @@ int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
 	return 0;
 }
 
+unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
+				       struct zone *zone,
+				       enum lru_list lru)
+{
+	int nid = zone->zone_pgdat->node_id;
+	int zid = zone_idx(zone);
+	struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+	return MEM_CGROUP_ZSTAT(mz, lru);
+}
+
 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 					struct list_head *dst,
 					unsigned long *scanned, int order,

mm/vmscan.c

@@ -139,6 +139,9 @@ static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
 static unsigned long zone_nr_pages(struct zone *zone, struct scan_control *sc,
 				   enum lru_list lru)
 {
+	if (!scan_global_lru(sc))
+		return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
+
 	return zone_page_state(zone, NR_LRU_BASE + lru);
 }