Comment "Why it's doing so" rather than "What it does" as proposed by Andrew Morton. Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> Reviewed-by: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- mm/vmscan.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- linux-next.orig/mm/vmscan.c 2012-12-10 10:42:58.674928674 +0800 +++ linux-next/mm/vmscan.c 2012-12-10 10:43:06.474928860 +0800 @@ -1177,7 +1177,11 @@ int isolate_lru_page(struct page *page) } /* - * Are there way too many processes in the direct reclaim path already? + * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and + * then get resheduled. When there are massive number of tasks doing page + * allocation, such sleeping direct reclaimers may keep piling up on each CPU, + * the LRU list will go small and be scanned faster than necessary, leading to + * unnecessary swapping, thrashing and OOM. */ static int too_many_isolated(struct zone *zone, int file, struct scan_control *sc) -- 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>