From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 3996C6B009C for ; Wed, 15 Jul 2009 22:39:03 -0400 (EDT) Date: Wed, 15 Jul 2009 22:38:53 -0400 From: Rik van Riel Subject: [PATCH -mm] throttle direct reclaim when too many pages are isolated already Message-ID: <20090715223854.7548740a@bree.surriel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , Wu Fengguang List-ID: When way too many processes go into direct reclaim, it is possible for all of the pages to be taken off the LRU. One result of this is that the next process in the page reclaim code thinks there are no reclaimable pages left and triggers an out of memory kill. One solution to this problem is to never let so many processes into the page reclaim path that the entire LRU is emptied. Limiting the system to only having half of each inactive list isolated for reclaim should be safe. Signed-off-by: Rik van Riel --- This patch goes on top of Kosaki's "Account the number of isolated pages" patch series. mm/vmscan.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) Index: mmotm/mm/vmscan.c =================================================================== --- mmotm.orig/mm/vmscan.c 2009-07-08 21:37:01.000000000 -0400 +++ mmotm/mm/vmscan.c 2009-07-08 21:39:02.000000000 -0400 @@ -1035,6 +1035,27 @@ int isolate_lru_page(struct page *page) } /* + * Are there way too many processes in the direct reclaim path already? + */ +static int too_many_isolated(struct zone *zone, int file) +{ + unsigned long inactive, isolated; + + if (current_is_kswapd()) + return 0; + + if (file) { + inactive = zone_page_state(zone, NR_INACTIVE_FILE); + isolated = zone_page_state(zone, NR_ISOLATED_FILE); + } else { + inactive = zone_page_state(zone, NR_INACTIVE_ANON); + isolated = zone_page_state(zone, NR_ISOLATED_ANON); + } + + return isolated > inactive; +} + +/* * shrink_inactive_list() is a helper for shrink_zone(). It returns the number * of reclaimed pages */ @@ -1049,6 +1070,10 @@ static unsigned long shrink_inactive_lis struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); int lumpy_reclaim = 0; + while (unlikely(too_many_isolated(zone, file))) { + schedule_timeout_interruptible(HZ/10); + } + /* * If we need a large contiguous chunk of memory, or have * trouble getting a small set of contiguous pages, we -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org