From: Wen Yang <wen.yang99@xxxxxxxxxx> Subject: mm/vmstat: fix divide error at __fragmentation_index 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. Should prevent reoccurrences of https://bugzilla.kernel.org/show_bug.cgi?id=196555 Link: http://lkml.kernel.org/r/1501751520-2598-1-git-send-email-wen.yang99@xxxxxxxxxx Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx> Reviewed-by: Jiang Biao <jiang.biao2@xxxxxxxxxx> Suggested-by: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmstat.c | 3 +++ 1 file changed, 3 insertions(+) diff -puN mm/vmstat.c~mm-vmstat-fix-divide-error-at-__fragmentation_index mm/vmstat.c --- a/mm/vmstat.c~mm-vmstat-fix-divide-error-at-__fragmentation_index +++ a/mm/vmstat.c @@ -870,6 +870,9 @@ static int __fragmentation_index(unsigne { unsigned long requested = 1UL << order; + if (WARN_ON_ONCE(order >= MAX_ORDER)) + return 0; + if (!info->free_blocks_total) return 0; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
