vmscan: avoid multiplication overflow in shrink_zone()

Local variable `scan' can overflow on zones which are larger than

	(2G * 4k) / 100 = 80GB.

Making it 64-bit on 64-bit will fix that up.

Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index eac9577941f935a0d8f281a6e851b68995e50314..5fa3eda1f03fccb6626f08c8e7bdad53326bce84 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1471,7 +1471,7 @@ static void shrink_zone(int priority, struct zone *zone,
 
        for_each_evictable_lru(l) {
                int file = is_file_lru(l);
-               int scan;
+               unsigned long scan;
 
                scan = zone_nr_pages(zone, sc, l);
                if (priority) {