From 9aa41348a8d11427feec350b21dcdd4330fd20c4 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 3 Jul 2013 15:01:48 -0700 Subject: [PATCH] mm: vmscan: do not allow kswapd to scan at maximum priority Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Kswapd can reach priority 0 quite easily if it is encountering a large number of pages it cannot reclaim such as pages under writeback. When this happens, kswapd reclaims very aggressively even though there may be no real risk of allocation failure or OOM. This patch prevents kswapd reaching priority 0 and trying to reclaim the world. Direct reclaimers will still reach priority 0 in the event of an OOM situation. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Acked-by: Johannes Weiner Reviewed-by: Michal Hocko Cc: KAMEZAWA Hiroyuki Cc: Jiri Slaby Cc: Valdis Kletnieks Tested-by: Zlatko Calusic Cc: dormando Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index cd0980393bac..1505c573719d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2929,7 +2929,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, */ if (raise_priority || !sc.nr_reclaimed) sc.priority--; - } while (sc.priority >= 0 && + } while (sc.priority >= 1 && !pgdat_balanced(pgdat, order, *classzone_idx)); out: