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Date: Wed, 15 Jul 2009 23:36:59 -0400 From: Rik van Riel <riel@...hat.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>, Wu Fengguang <fengguang.wu@...el.com> Subject: [PATCH -mm] throttle direct reclaim when too many pages are isolated already (v2) 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 <riel@...hat.com> --- v2: fix the bugs pointed out by Andrew Morton This patch goes on top of Kosaki's "Account the number of isolated pages" patch series. mm/vmscan.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) Index: mmotm/mm/vmscan.c =================================================================== --- mmotm.orig/mm/vmscan.c 2009-07-15 22:32:35.000000000 -0400 +++ mmotm/mm/vmscan.c 2009-07-15 23:26:37.000000000 -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 +1070,14 @@ 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))) { + /* We are about to die and free our memory. Return now. */ + if (fatal_signal_pending(current)) + return SWAP_CLUSTER_MAX; + + congestion_wait(WRITE, HZ/10); + } + /* * If we need a large contiguous chunk of memory, or have * trouble getting a small set of contiguous pages, we -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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