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: 599d0c9 ("mm, vmscan: move LRU lists to node") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Johannes Weiner <[email protected]> Acked-by: Hillf Danton <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: Jia He <[email protected]> Cc: Mel Gorman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
gibsson · May 3, 2017 · d450abd · d450abd
1 parent c73322d
commit d450abd
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/mm/vmscan.c b/mm/vmscan.c
@@ -2835,8 +2835,10 @@ static bool allow_direct_reclaim(pg_data_t *pgdat)
 
 	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);