Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752527AbcCKTIR (ORCPT ); Fri, 11 Mar 2016 14:08:17 -0500 Received: from mail-pa0-f45.google.com ([209.85.220.45]:36027 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750929AbcCKTIO (ORCPT ); Fri, 11 Mar 2016 14:08:14 -0500 Date: Fri, 11 Mar 2016 11:08:05 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Michal Hocko cc: Hugh Dickins , 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 In-Reply-To: <20160311130647.GO27701@dhcp22.suse.cz> Message-ID: 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> <20160311130647.GO27701@dhcp22.suse.cz> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2958 Lines: 64 On Fri, 11 Mar 2016, Michal Hocko wrote: > 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. Three have been stably running load for between 6 and 7 hours now, no problems, looking very good: Tested-by: Hugh Dickins I'll be interested to see how my huge tmpfs loads fare with the rework, but I'm not quite ready to try that today; and any issue there (I've no reason to suppose that there will be) can be a separate investigation for me to make at some future date. It was this order=2 regression that was holding me back, and I've now no objection to your patches (though nobody should imagine that I've actually studied them). Thank you, Michal. Hugh