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    Subject[PATCH v2 1/2] vmscan: don't subtraction of unsined
    Date
    'slab_reclaimable' and 'nr_pages' are unsigned. so, subtraction is
    unsafe.

    Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Acked-by: Christoph Lameter <cl@linux-foundation.org>
    ---
    mm/vmscan.c | 14 +++++++-------
    1 files changed, 7 insertions(+), 7 deletions(-)

    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index 9c7e57c..8715da1 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -2588,7 +2588,7 @@ 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 n, m;

    disable_swap_token();
    cond_resched();
    @@ -2615,8 +2615,8 @@ 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) {
    + n = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
    + if (n > 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
    @@ -2628,16 +2628,16 @@ 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 > n))
    ;

    /*
    * 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);
    + m = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
    + if (m < n)
    + sc.nr_reclaimed += n - m;
    }

    p->reclaim_state = NULL;
    --
    1.6.5.2




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