memcg: remove mem_cgroup_calc_mapped_ratio()

Currently, mem_cgroup_calc_mapped_ratio() is unused at all.  it can be
removed and KAMEZAWA-san suggested it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.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>

include/linux/memcontrol.h

@@ -88,7 +88,6 @@ extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
 /*
  * For memory reclaim.
  */
-extern int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem);
 extern long mem_cgroup_reclaim_imbalance(struct mem_cgroup *mem);
 
 extern int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem);
@@ -211,11 +210,6 @@ static inline void mem_cgroup_end_migration(struct mem_cgroup *mem,
 {
 }
 
-static inline int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
-{
-	return 0;
-}
-
 static inline int mem_cgroup_reclaim_imbalance(struct mem_cgroup *mem)
 {
 	return 0;

mm/memcontrol.c

@@ -507,23 +507,6 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
 	return ret;
 }
 
-/*
- * Calculate mapped_ratio under memory controller. This will be used in
- * vmscan.c for deteremining we have to reclaim mapped pages.
- */
-int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
-{
-	long total, rss;
-
-	/*
-	 * usage is recorded in bytes. But, here, we assume the number of
-	 * physical pages can be represented by "long" on any arch.
-	 */
-	total = (long) (mem->res.usage >> PAGE_SHIFT) + 1L;
-	rss = (long)mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
-	return (int)((rss * 100L) / total);
-}
-
 /*
  * prev_priority control...this will be used in memory reclaim path.
  */