From 15748048991e801a2d18ce5da4e0d528852bc106 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Mon, 9 Aug 2010 17:19:50 -0700 Subject: [PATCH] vmscan: avoid subtraction of unsigned types 'slab_reclaimable' and 'nr_pages' are unsigned. Subtraction is unsafe because negative results would be misinterpreted. Signed-off-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Cc: Mel Gorman Cc: Rik van Riel Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 1c3d960de9d..1b4e4a597ca 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2600,7 +2600,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) .swappiness = vm_swappiness, .order = order, }; - unsigned long slab_reclaimable; + unsigned long nr_slab_pages0, nr_slab_pages1; cond_resched(); /* @@ -2625,8 +2625,8 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) } while (priority >= 0 && sc.nr_reclaimed < nr_pages); } - slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); - if (slab_reclaimable > zone->min_slab_pages) { + nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); + if (nr_slab_pages0 > zone->min_slab_pages) { /* * shrink_slab() does not currently allow us to determine how * many pages were freed in this zone. So we take the current @@ -2638,16 +2638,17 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) * take a long time. */ while (shrink_slab(sc.nr_scanned, gfp_mask, order) && - zone_page_state(zone, NR_SLAB_RECLAIMABLE) > - slab_reclaimable - nr_pages) + (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages > + nr_slab_pages0)) ; /* * Update nr_reclaimed by the number of slab pages we * reclaimed from this zone. */ - sc.nr_reclaimed += slab_reclaimable - - zone_page_state(zone, NR_SLAB_RECLAIMABLE); + nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); + if (nr_slab_pages1 < nr_slab_pages0) + sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; } p->reclaim_state = NULL; -- 2.20.1