mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()

The value of nr_reclaimed is the number of pages reclaimed in the current
round of the loop, whereas nr_to_reclaim should be compared with the
number of pages reclaimed in all rounds.

In each round of the loop, reclaimed pages are cut off from the reclaim
goal, and the loop stops once the goal achieved.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: 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>

1 files changed, 6 insertions, 1 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 61a66881235d..8dfa59866af2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2112,7 +2112,12 @@ restart:
                  * with multiple processes reclaiming pages, the total
                  * freeing target can get unreasonably large.
                  */
-                if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
+                if (nr_reclaimed >= nr_to_reclaim)
+                        nr_to_reclaim = 0;
+                else
+                        nr_to_reclaim -= nr_reclaimed;
+
+                if (!nr_to_reclaim && priority < DEF_PRIORITY)
                         break;
         }
         blk_finish_plug(&plug);