From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling
PF_MEMALLOC direct reclaimers get throttled on a node when the sum of all
free pages in each zone fall below half the min watermark. During the
summation, we want to exclude zones that don't have reclaimables.
Checking the same pgdat over and over again doesn't make sense.
Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
Link: http://lkml.kernel.org/r/20170228214007.5621-3-hannes@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jia He <hejianet@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN mm/vmscan.c~mm-fix-check-for-reclaimable-pages-in-pf_memalloc-reclaim-throttling mm/vmscan.c
--- a/mm/vmscan.c~mm-fix-check-for-reclaimable-pages-in-pf_memalloc-reclaim-throttling
+++ a/mm/vmscan.c
@@ -2835,8 +2835,10 @@ static bool allow_direct_reclaim(pg_data
for (i = 0; i <= ZONE_NORMAL; i++) {
zone = &pgdat->node_zones[i];
- if (!managed_zone(zone) ||
- pgdat_reclaimable_pages(pgdat) == 0)
+ if (!managed_zone(zone))
+ continue;
+
+ if (!zone_reclaimable_pages(zone))
continue;
pfmemalloc_reserve += min_wmark_pages(zone);
_
--
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