Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752905AbcCKNG5 (ORCPT ); Fri, 11 Mar 2016 08:06:57 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34989 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215AbcCKNGu (ORCPT ); Fri, 11 Mar 2016 08:06:50 -0500 Date: Fri, 11 Mar 2016 14:06:47 +0100 From: Michal Hocko To: Hugh Dickins Cc: Andrew Morton , Sergey Senozhatsky , Vlastimil Babka , Linus Torvalds , Johannes Weiner , Mel Gorman , David Rientjes , Tetsuo Handa , Hillf Danton , KAMEZAWA Hiroyuki , Joonsoo Kim , linux-mm@kvack.org, LKML Subject: Re: [PATCH 3/3] mm, oom: protect !costly allocations some more Message-ID: <20160311130647.GO27701@dhcp22.suse.cz> References: <20160307160838.GB5028@dhcp22.suse.cz> <1457444565-10524-1-git-send-email-mhocko@kernel.org> <1457444565-10524-4-git-send-email-mhocko@kernel.org> <20160309111109.GG27018@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3026 Lines: 72 On Fri 11-03-16 04:17:30, Hugh Dickins wrote: > On Wed, 9 Mar 2016, Michal Hocko wrote: > > Joonsoo has pointed out that this attempt is still not sufficient > > becasuse we might have invoked only a single compaction round which > > is might be not enough. I fully agree with that. Here is my take on > > that. It is again based on the number of retries loop. > > > > I was also playing with an idea of doing something similar to the > > reclaim retry logic: > > if (order) { > > if (compaction_made_progress(compact_result) > > no_compact_progress = 0; > > else if (compaction_failed(compact_result) > > no_compact_progress++; > > } > > but it is compaction_failed() part which is not really > > straightforward to define. Is it COMPACT_NO_SUITABLE_PAGE > > resp. COMPACT_NOT_SUITABLE_ZONE sufficient? compact_finished and > > compaction_suitable however hide this from compaction users so it > > seems like we can never see it. > > > > Maybe we can update the feedback mechanism from the compaction but > > retries count seems reasonably easy to understand and pragmatic. If > > we cannot form a order page after we tried for N times then it really > > doesn't make much sense to continue and we are oom for this order. I am > > holding my breath to hear from Hugh on this, though. > > Never a wise strategy. But I just got around to it tonight. > > I do believe you've nailed it with this patch! Thank you! That's a great news! Thanks for testing. > I've applied 1/3, 2/3 and this (ah, it became the missing 3/3 later on) > on top of 4.5.0-rc5-mm1 (I think there have been a couple of mmotms since, > but I've not got to them yet): so far it is looking good on all machines. > > After a quick go with the simple make -j20 in tmpfs, which survived > a cycle on the laptop, I've switched back to my original tougher load, > and that's going well so far: no sign of any OOMs. But I've interrupted > on the laptop to report back to you now, then I'll leave it running > overnight. OK, let's wait for the rest of the tests but I find it really optimistic considering how easily you could trigger the issue previously. Anyway I hope for your Tested-by after you are reasonably confident your loads are behaving well. [...] > > diff --git a/include/linux/compaction.h b/include/linux/compaction.h > > index b167801187e7..7d028ccf440a 100644 > > --- a/include/linux/compaction.h > > +++ b/include/linux/compaction.h > > @@ -61,6 +61,12 @@ extern void compaction_defer_reset(struct zone *zone, int order, > > bool alloc_success); > > extern bool compaction_restarting(struct zone *zone, int order); > > > > +static inline bool compaction_made_progress(enum compact_result result) > > +{ > > + return (compact_result > COMPACT_SKIPPED && > > + compact_result < COMPACT_NO_SUITABLE_PAGE) > > That line didn't build at all: > > return result > COMPACT_SKIPPED && result < COMPACT_NO_SUITABLE_PAGE; those last minute changes... Sorry about that. Fixed. Thanks! -- Michal Hocko SUSE Labs