memcg: remove unused retry signal from reclaim

If the memcg reclaim code detects the target memcg below its limit it
exits and returns a guaranteed non-zero value so that the charge is
retried.

Nowadays, the charge side checks the memcg limit itself and does not rely
on this non-zero return value trick.

This patch removes it.  The reclaim code will now always return the true
number of pages it reclaimed on its own.

Signed-off-by: Johannes Weiner <[email protected]>
Acked-by: Rik van Riel<[email protected]>
Acked-by: Ying Han<[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Reviewed-by: Michal Hocko <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Daisuke Nishimura <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/memcontrol.c

@@ -1596,7 +1596,7 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
 			if (!res_counter_soft_limit_excess(&root_mem->res))
 				return total;
 		} else if (mem_cgroup_margin(root_mem))
-			return 1 + total;
+			return total;
 	}
 	return total;
 }