When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error. Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the
patch can make it more robust.
Sugguested-by: VlastimilBabka <vba...@suse.cz>
Signed-off-by: Wen Yang <wen.yan...@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.bi...@zte.com.cn>
---
mm/vmstat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..6f0f1ae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct
contig_page_info *in
{
unsigned long requested = 1UL << order;
+ if (WARN_ON_ONCE(order >= MAX_ORDER))
+ return 0;
+
if (!info->free_blocks_total)
return 0;
--
2.7.4
