isolate_migratepages_range() might isolate none pages, for example, when zone->lru_lock is contended and compaction is async. In this case, we should abort compaction, otherwise, compact_zone will run a useless loop and make zone->lru_lock is even contended. Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx> --- mm/compaction.c | 2 ++ 1 file changed, 2 insertions(+) Index: linux/mm/compaction.c =================================================================== --- linux.orig/mm/compaction.c 2012-08-22 09:51:39.295322268 +0800 +++ linux/mm/compaction.c 2012-09-06 14:46:13.923144263 +0800 @@ -402,6 +402,8 @@ isolate_migratepages_range(struct zone * trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); + if (!nr_isolated) + return 0; return low_pfn; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>