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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-08-10 00:19:50 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-10 03:45:02 (GMT)
commit15748048991e801a2d18ce5da4e0d528852bc106 (patch)
treee31dcdf36bbcfdd1c78546637d59faa963597bac /mm/vmscan.c
parent7ee92255470daa0edb93866aec6e27534cd9a177 (diff)
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 <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1c3d960d..1b4e4a5 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;

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