include/linux/memcontrol.h: fix comments based on per-node memcg

These comments should be updated as memcg limit enforcement has been
moved from zones to nodes.

Link: http://lkml.kernel.org/r/20191022150618.GA15519@haolee.github.ioSigned-off-by: NHao Lee <haolee.swjtu@gmail.com>
Acked-by: NRoman Gushchin <guro@fb.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -111,7 +111,7 @@ struct memcg_shrinker_map {
 };
 
 /*
- * per-zone information in memory controller.
+ * per-node information in memory controller.
  */
 struct mem_cgroup_per_node {
 	struct lruvec		lruvec;
@@ -398,8 +398,7 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
  * @memcg: memcg of the wanted lruvec
  *
  * Returns the lru list vector holding pages for a given @node or a given
- * @memcg and @zone. This can be the node lruvec, if the memory controller
- * is disabled.
+ * @memcg. This can be the node lruvec, if the memory controller is disabled.
  */
 static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
 				struct mem_cgroup *memcg)