memcg: fix zone congestion
ZONE_CONGESTED should be a state of global memory reclaim. If not, a busy
memcg sets this and give unnecessary throttoling in wait_iff_congested()
against memory recalim in other contexts. This makes system performance
bad.
I'll think about "memcg is congested!" flag is required or not, later.
But this fix is required first.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Ying Han <yinghan@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f6b435c..8bfd450 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -937,7 +937,7 @@
* back off and wait for congestion to clear because further reclaim
* will encounter the same problem
*/
- if (nr_dirty == nr_congested && nr_dirty != 0)
+ if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc))
zone_set_flag(zone, ZONE_CONGESTED);
free_page_list(&free_pages);