From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 65A4E6B00AB for ; Thu, 1 Jan 2009 09:52:19 -0500 (EST) Date: Thu, 1 Jan 2009 23:52:02 +0900 (JST) From: KOSAKI Motohiro Subject: [PATCH] mm: stop kswapd's infinite loop at high order allocation take2 In-Reply-To: <20081231215934.1296.KOSAKI.MOTOHIRO@jp.fujitsu.com> References: <20081231115332.GB20534@csn.ul.ie> <20081231215934.1296.KOSAKI.MOTOHIRO@jp.fujitsu.com> Message-Id: <20090101021240.A057.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm , Andrew Morton , Nick Piggin , wassim dagash List-ID: > > /* > > * Fragmentation may mean that the system cannot be > > * rebalanced for high-order allocations in all zones. > > * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, > > * it means the zones have been fully scanned and are still > > * not balanced. For high-order allocations, there is > > * little point trying all over again as kswapd may > > * infinite loop. > > * > > * Instead, recheck all watermarks at order-0 as they > > * are the most important. If watermarks are ok, kswapd will go > > * back to sleep. High-order users can still direct reclaim > > * if they wish. > > */ > > > > ? > > Excellent. I strongly like this and I hope merge it to my patch. > I'll resend new patch. Done. == From: KOSAKI Motohiro Subject: [PATCH] mm: kswapd stop infinite loop at high order allocation Wassim Dagash reported following kswapd infinite loop problem. kswapd runs in some infinite loop trying to swap until order 10 of zone highmem is OK.... kswapd will continue to try to balance order 10 of zone highmem forever (or until someone release a very large chunk of highmem). For non order-0 allocations, the system may never be balanced due to fragmentation but kswapd should not infinitely loop as a result. Instead, recheck all watermarks at order-0 as they are the most important. If watermarks are ok, kswapd will go back to sleep. Reported-by: wassim dagash Signed-off-by: KOSAKI Motohiro Reviewed-by: Nick Piggin Signed-off-by: Mel Gorman , --- mm/vmscan.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) Index: b/mm/vmscan.c =================================================================== --- a/mm/vmscan.c 2008-12-25 08:26:37.000000000 +0900 +++ b/mm/vmscan.c 2009-01-01 01:56:02.000000000 +0900 @@ -1872,6 +1872,23 @@ out: try_to_freeze(); + /* + * Fragmentation may mean that the system cannot be + * rebalanced for high-order allocations in all zones. + * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, + * it means the zones have been fully scanned and are still + * not balanced. For high-order allocations, there is + * little point trying all over again as kswapd may + * infinite loop. + * + * Instead, recheck all watermarks at order-0 as they + * are the most important. If watermarks are ok, kswapd will go + * back to sleep. High-order users can still direct reclaim + * if they wish. + */ + if (nr_reclaimed < SWAP_CLUSTER_MAX) + order = sc.order = 0; + goto loop_again; } -- 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