Commit d450abd8 authored May 03, 2017 by Johannes Weiner Committed by Linus Torvalds May 03, 2017

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: 599d0c95 ("mm, vmscan: move LRU lists to node")
Link: http://lkml.kernel.org/r/20170228214007.5621-3-hannes@cmpxchg.org


Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c73322d0

mm/vmscan.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -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);

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