mm/memcg: move reclaim_stat into lruvec

With mem_cgroup_disabled() now explicit, it becomes clear that the
zone_reclaim_stat structure actually belongs in lruvec, per-zone when
memcg is disabled but per-memcg per-zone when it's enabled.

We can delete mem_cgroup_get_reclaim_stat(), and change
update_page_reclaim_stat() to update just the one set of stats, the one
which get_scan_count() will actually use.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 16 insertions, 38 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 30f938c..00c8898 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -138,7 +138,6 @@ struct mem_cgroup_per_zone {
 
 	struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];
 
-	struct zone_reclaim_stat reclaim_stat;
 	struct rb_node		tree_node;	/* RB tree node */
 	unsigned long long	usage_in_excess;/* Set to the value by which */
 						/* the soft limit is exceeded*/
@@ -1243,16 +1242,6 @@ int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone *zone)
 	return (active > inactive);
 }
 
-struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
-						      struct zone *zone)
-{
-	int nid = zone_to_nid(zone);
-	int zid = zone_idx(zone);
-	struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
-
-	return &mz->reclaim_stat;
-}
-
 struct zone_reclaim_stat *
 mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 {
@@ -1268,7 +1257,7 @@ 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);
-	return &mz->reclaim_stat;
+	return &mz->lruvec.reclaim_stat;
 }
 
 #define mem_cgroup_from_res_counter(counter, member)	\
@@ -4216,21 +4205,19 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
 	{
 		int nid, zid;
 		struct mem_cgroup_per_zone *mz;
+		struct zone_reclaim_stat *rstat;
 		unsigned long recent_rotated[2] = {0, 0};
 		unsigned long recent_scanned[2] = {0, 0};
 
 		for_each_online_node(nid)
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
 				mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+				rstat = &mz->lruvec.reclaim_stat;
 
-				recent_rotated[0] +=
-					mz->reclaim_stat.recent_rotated[0];
-				recent_rotated[1] +=
-					mz->reclaim_stat.recent_rotated[1];
-				recent_scanned[0] +=
-					mz->reclaim_stat.recent_scanned[0];
-				recent_scanned[1] +=
-					mz->reclaim_stat.recent_scanned[1];
+				recent_rotated[0] += rstat->recent_rotated[0];
+				recent_rotated[1] += rstat->recent_rotated[1];
+				recent_scanned[0] += rstat->recent_scanned[0];
+				recent_scanned[1] += rstat->recent_scanned[1];
 			}
 		cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
 		cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4fc462b..8cbfc38 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4410,10 +4410,10 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
 		zone_pcp_init(zone);
 		for_each_lru(lru)
 			INIT_LIST_HEAD(&zone->lruvec.lists[lru]);
-		zone->reclaim_stat.recent_rotated[0] = 0;
-		zone->reclaim_stat.recent_rotated[1] = 0;
-		zone->reclaim_stat.recent_scanned[0] = 0;
-		zone->reclaim_stat.recent_scanned[1] = 0;
+		zone->lruvec.reclaim_stat.recent_rotated[0] = 0;
+		zone->lruvec.reclaim_stat.recent_rotated[1] = 0;
+		zone->lruvec.reclaim_stat.recent_scanned[0] = 0;
+		zone->lruvec.reclaim_stat.recent_scanned[1] = 0;
 		zap_zone_vm_stats(zone);
 		zone->flags = 0;
 		if (!size)
diff --git a/mm/swap.c b/mm/swap.c
index 6fdd72e..0503ad7 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -312,21 +312,15 @@ void rotate_reclaimable_page(struct page *page)
 static void update_page_reclaim_stat(struct zone *zone, struct page *page,
 				     int file, int rotated)
 {
-	struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
-	struct zone_reclaim_stat *memcg_reclaim_stat;
+	struct zone_reclaim_stat *reclaim_stat;
 
-	memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
+	reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
+	if (!reclaim_stat)
+		reclaim_stat = &zone->lruvec.reclaim_stat;
 
 	reclaim_stat->recent_scanned[file]++;
 	if (rotated)
 		reclaim_stat->recent_rotated[file]++;
-
-	if (!memcg_reclaim_stat)
-		return;
-
-	memcg_reclaim_stat->recent_scanned[file]++;
-	if (rotated)
-		memcg_reclaim_stat->recent_rotated[file]++;
 }
 
 static void __activate_page(struct page *page, void *arg)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 52fac58..e234ada 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -149,10 +149,7 @@ static bool global_reclaim(struct scan_control *sc)
 
 static struct zone_reclaim_stat *get_reclaim_stat(struct mem_cgroup_zone *mz)
 {
-	if (!mem_cgroup_disabled())
-		return mem_cgroup_get_reclaim_stat(mz->mem_cgroup, mz->zone);
-
-	return &mz->zone->reclaim_stat;
+	return &mem_cgroup_zone_lruvec(mz->zone, mz->mem_cgroup)->reclaim_stat;
 }
 
 static unsigned long zone_nr_lru_pages(struct mem_cgroup_zone *mz,