mm/memcg: replace inexistence move_lock_page_cgroup() by move_lock_mem_cgroup() in comment

Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -1898,7 +1898,7 @@ again:
 		return;
 	/*
 	 * If this memory cgroup is not under account moving, we don't
-	 * need to take move_lock_page_cgroup(). Because we already hold
+	 * need to take move_lock_mem_cgroup(). Because we already hold
 	 * rcu_read_lock(), any calls to move_account will be delayed until
 	 * rcu_read_unlock() if mem_cgroup_stolen() == true.
 	 */
@@ -1920,7 +1920,7 @@ void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
 	/*
 	 * It's guaranteed that pc->mem_cgroup never changes while
 	 * lock is held because a routine modifies pc->mem_cgroup
-	 * should take move_lock_page_cgroup().
+	 * should take move_lock_mem_cgroup().
 	 */
 	move_unlock_mem_cgroup(pc->mem_cgroup, flags);
 }