Up until '3e7d344 mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim', compaction skipped calculating the fragmentation index of a zone when compaction was explicitely requested through the procfs knob. However, when compaction_suitable was introduced, it did not come with an extra check for order == -1, set on explicit compaction requests, and passed this order on to the fragmentation index calculation, where it overshifts the number of requested pages, leading to a division by zero. This patch makes sure that order == -1 is recognized as the flag it is rather than passing it along as valid order parameter. Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> --- mm/compaction.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 6d592a0..114c145 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -453,6 +453,9 @@ unsigned long compaction_suitable(struct zone *zone, int order) if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) return COMPACT_SKIPPED; + if (order == -1) + return COMPACT_CONTINUE; + /* * fragmentation index determines if allocation failures are due to * low memory or external fragmentation -- 1.7.3.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>