mm: memcontrol: replace zone summing with lruvec_page_state()

Instead of adding up the zone counters, use lruvec_page_state() to get the
node state directly.  This is a bit cheaper and more stream-lined.

Link: http://lkml.kernel.org/r/20190228163020.24100-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index b238403..65f381b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -505,19 +505,6 @@
 					   int nid, unsigned int lru_mask);
 
 static inline
-unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
-{
-	struct mem_cgroup_per_node *mz;
-	unsigned long nr_pages = 0;
-	int zid;
-
-	mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
-	for (zid = 0; zid < MAX_NR_ZONES; zid++)
-		nr_pages += mz->lru_zone_size[zid][lru];
-	return nr_pages;
-}
-
-static inline
 unsigned long mem_cgroup_get_zone_lru_size(struct lruvec *lruvec,
 		enum lru_list lru, int zone_idx)
 {
@@ -960,11 +947,6 @@
 	return true;
 }
 
-static inline unsigned long
-mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
-{
-	return 0;
-}
 static inline
 unsigned long mem_cgroup_get_zone_lru_size(struct lruvec *lruvec,
 		enum lru_list lru, int zone_idx)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 81a0d39..f303814 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -737,7 +737,7 @@
 	for_each_lru(lru) {
 		if (!(BIT(lru) & lru_mask))
 			continue;
-		nr += mem_cgroup_get_lru_size(lruvec, lru);
+		nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru);
 	}
 	return nr;
 }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 39912c6..e869f9e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -346,7 +346,7 @@
 	int zid;
 
 	if (!mem_cgroup_disabled())
-		lru_size = mem_cgroup_get_lru_size(lruvec, lru);
+		lru_size = lruvec_page_state(lruvec, NR_LRU_BASE + lru);
 	else
 		lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);