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vmscan: avoid subtraction of unsigned types

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'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>
This commit is contained in:
KOSAKI Motohiro 2010-08-09 17:19:50 -07:00 committed by Linus Torvalds
parent 7ee9225547
commit 1574804899
1 changed files with 8 additions and 7 deletions
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15
mm/vmscan.c
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@ -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;