From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752163AbcGUJQn (ORCPT ); Thu, 21 Jul 2016 05:16:43 -0400 Received: from outbound-smtp07.blacknight.com ([46.22.139.12]:55613 "EHLO outbound-smtp07.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752156AbcGUJQh (ORCPT ); Thu, 21 Jul 2016 05:16:37 -0400 Date: Thu, 21 Jul 2016 10:16:33 +0100 From: Mel Gorman To: Joonsoo Kim Cc: Andrew Morton , Johannes Weiner , Minchan Kim , Michal Hocko , Vlastimil Babka , Linux-MM , LKML Subject: Re: [PATCH 0/5] Candidate fixes for premature OOM kills with node-lru v1 Message-ID: <20160721091633.GI10438@techsingularity.net> References: <1469028111-1622-1-git-send-email-mgorman@techsingularity.net> <20160721073156.GC27554@js1304-P5Q-DELUXE> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20160721073156.GC27554@js1304-P5Q-DELUXE> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 21, 2016 at 04:31:56PM +0900, Joonsoo Kim wrote: > On Wed, Jul 20, 2016 at 04:21:46PM +0100, Mel Gorman wrote: > > Both Joonsoo Kim and Minchan Kim have reported premature OOM kills on > > a 32-bit platform. The common element is a zone-constrained high-order > > allocation failing. Two factors appear to be at fault -- pgdat being > > considered unreclaimable prematurely and insufficient rotation of the > > active list. > > > > Unfortunately to date I have been unable to reproduce this with a variety > > of stress workloads on a 2G 32-bit KVM instance. It's not clear why as > > the steps are similar to what was described. It means I've been unable to > > determine if this series addresses the problem or not. I'm hoping they can > > test and report back before these are merged to mmotm. What I have checked > > is that a basic parallel DD workload completed successfully on the same > > machine I used for the node-lru performance tests. I'll leave the other > > tests running just in case anything interesting falls out. > > Hello, Mel. > > I tested this series and it doesn't solve my problem. But, with this > series and one change below, my problem is solved. > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index f5ab357..d451c29 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1819,7 +1819,7 @@ static void move_active_pages_to_lru(struct lruvec *lruvec, > > nr_pages = hpage_nr_pages(page); > update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); > - list_move(&page->lru, &lruvec->lists[lru]); > + list_move_tail(&page->lru, &lruvec->lists[lru]); > pgmoved += nr_pages; > > if (put_page_testzero(page)) { > > It is brain-dead work-around so it is better you to find a better solution. > This wrecks LRU ordering. > I guess that, in my test, file reference happens very quickly. So, if there are > many skip candidates, reclaimable pages on lower zone cannot be reclaimed easily > due to re-reference. If I apply above work-around, the test is finally passed. > I think by scaling skipped pages as partial scan that it may address the issue. > One more note that, in my test, 1/5 patch have a negative impact. Sometime, > system lock-up happens and elapsed time is also worse than the test without it. > > Anyway, it'd be good to post my test script and program. > > setup: 64 bit 2000 MB (500 MB DMA32 and 1500 MB MOVABLE) > Thanks. I partially replicated this with a 32-bit machine and minor modifications. It triggered an OOM within 5 minutes. I'll test the revised series shortly and when/if it's successful I'll post a V2 of the series. -- Mel Gorman SUSE Labs