mm: memcontrol: clean up memcg zoneinfo lookup

Memcg zoneinfo lookup sites have either the page, the zone, or the node
id and zone index, but sites that only have the zone have to look up the
node id and zone index themselves, whereas sites that already have those
two integers use a function for a simple pointer chase.

Provide mem_cgroup_zone_zoneinfo() that takes a zone pointer and let
sites that already have node id and zone index - all for each node, for
each zone iterators - use &memcg->nodeinfo[nid]->zoneinfo[zid].

Rename page_cgroup_zoneinfo() to mem_cgroup_page_zoneinfo() to match.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -676,9 +676,11 @@ static void disarm_static_keys(struct mem_cgroup *memcg)
 static void drain_all_stock_async(struct mem_cgroup *memcg);
 
 static struct mem_cgroup_per_zone *
-mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
+mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
 {
-	VM_BUG_ON((unsigned)nid >= nr_node_ids);
+	int nid = zone_to_nid(zone);
+	int zid = zone_idx(zone);
+
 	return &memcg->nodeinfo[nid]->zoneinfo[zid];
 }
 
@@ -688,12 +690,12 @@ struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
 }
 
 static struct mem_cgroup_per_zone *
-page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
+mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
 {
 	int nid = page_to_nid(page);
 	int zid = page_zonenum(page);
 
-	return mem_cgroup_zoneinfo(memcg, nid, zid);
+	return &memcg->nodeinfo[nid]->zoneinfo[zid];
 }
 
 static struct mem_cgroup_tree_per_zone *
@@ -772,16 +774,14 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
 	unsigned long long excess;
 	struct mem_cgroup_per_zone *mz;
 	struct mem_cgroup_tree_per_zone *mctz;
-	int nid = page_to_nid(page);
-	int zid = page_zonenum(page);
-	mctz = soft_limit_tree_from_page(page);
 
+	mctz = soft_limit_tree_from_page(page);
 	/*
 	 * Necessary to update all ancestors when hierarchy is used.
 	 * because their event counter is not touched.
 	 */
 	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
-		mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+		mz = mem_cgroup_page_zoneinfo(memcg, page);
 		excess = res_counter_soft_limit_excess(&memcg->res);
 		/*
 		 * We have to update the tree if mz is on RB-tree or
@@ -804,14 +804,14 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
 
 static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
 {
-	int node, zone;
-	struct mem_cgroup_per_zone *mz;
 	struct mem_cgroup_tree_per_zone *mctz;
+	struct mem_cgroup_per_zone *mz;
+	int nid, zid;
 
-	for_each_node(node) {
-		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
-			mz = mem_cgroup_zoneinfo(memcg, node, zone);
-			mctz = soft_limit_tree_node_zone(node, zone);
+	for_each_node(nid) {
+		for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+			mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+			mctz = soft_limit_tree_node_zone(nid, zid);
 			mem_cgroup_remove_exceeded(memcg, mz, mctz);
 		}
 	}
@@ -946,8 +946,7 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
 	__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
 }
 
-unsigned long
-mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
+unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
 {
 	struct mem_cgroup_per_zone *mz;
 
@@ -955,46 +954,38 @@ mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
 	return mz->lru_size[lru];
 }
 
-static unsigned long
-mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
-			unsigned int lru_mask)
-{
-	struct mem_cgroup_per_zone *mz;
-	enum lru_list lru;
-	unsigned long ret = 0;
-
-	mz = mem_cgroup_zoneinfo(memcg, nid, zid);
-
-	for_each_lru(lru) {
-		if (BIT(lru) & lru_mask)
-			ret += mz->lru_size[lru];
-	}
-	return ret;
-}
-
-static unsigned long
-mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
-			int nid, unsigned int lru_mask)
+static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+						  int nid,
+						  unsigned int lru_mask)
 {
-	u64 total = 0;
+	unsigned long nr = 0;
 	int zid;
 
-	for (zid = 0; zid < MAX_NR_ZONES; zid++)
-		total += mem_cgroup_zone_nr_lru_pages(memcg,
-						nid, zid, lru_mask);
+	VM_BUG_ON((unsigned)nid >= nr_node_ids);
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+		struct mem_cgroup_per_zone *mz;
+		enum lru_list lru;
 
-	return total;
+		for_each_lru(lru) {
+			if (!(BIT(lru) & lru_mask))
+				continue;
+			mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
+			nr += mz->lru_size[lru];
+		}
+	}
+	return nr;
 }
 
 static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
 			unsigned int lru_mask)
 {
+	unsigned long nr = 0;
 	int nid;
-	u64 total = 0;
 
 	for_each_node_state(nid, N_MEMORY)
-		total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
-	return total;
+		nr += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
+	return nr;
 }
 
 static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
@@ -1242,11 +1233,9 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 		int uninitialized_var(seq);
 
 		if (reclaim) {
-			int nid = zone_to_nid(reclaim->zone);
-			int zid = zone_idx(reclaim->zone);
 			struct mem_cgroup_per_zone *mz;
 
-			mz = mem_cgroup_zoneinfo(root, nid, zid);
+			mz = mem_cgroup_zone_zoneinfo(root, reclaim->zone);
 			iter = &mz->reclaim_iter[reclaim->priority];
 			if (prev && reclaim->generation != iter->generation) {
 				iter->last_visited = NULL;
@@ -1353,7 +1342,7 @@ struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
 		goto out;
 	}
 
-	mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
+	mz = mem_cgroup_zone_zoneinfo(memcg, zone);
 	lruvec = &mz->lruvec;
 out:
 	/*
@@ -1412,7 +1401,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone)
 	if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup)
 		pc->mem_cgroup = memcg = root_mem_cgroup;
 
-	mz = page_cgroup_zoneinfo(memcg, page);
+	mz = mem_cgroup_page_zoneinfo(memcg, page);
 	lruvec = &mz->lruvec;
 out:
 	/*
@@ -5305,7 +5294,7 @@ static int memcg_stat_show(struct seq_file *m, void *v)
 
 		for_each_online_node(nid)
 			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-				mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+				mz = &memcg->nodeinfo[nid]->zoneinfo[zid];
 				rstat = &mz->lruvec.reclaim_stat;
 
 				recent_rotated[0] += rstat->recent_rotated[0];