mm: fix overflow in find_zone_movable_pfns_for_nodes()

If the user set "movablecore=xx" to a large number, corepages will
overflow.  Fix the problem.

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Tang Chen <tangchen@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c60605df9b48e03b79555b23b8b3f0e48d769a3e..4aed338fc5350544680dbbaf2e5c637b8327ca10 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5666,6 +5666,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
                 */
                required_movablecore =
                        roundup(required_movablecore, MAX_ORDER_NR_PAGES);
+               required_movablecore = min(totalpages, required_movablecore);
                corepages = totalpages - required_movablecore;
 
                required_kernelcore = max(required_kernelcore, corepages);