From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 202C26B0005 for ; Wed, 4 May 2016 14:20:52 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id j8so48166328lfd.0 for ; Wed, 04 May 2016 11:20:52 -0700 (PDT) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id q133si6584412wmd.109.2016.05.04.11.20.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 May 2016 11:20:51 -0700 (PDT) Received: by mail-wm0-f68.google.com with SMTP id n129so12267356wmn.1 for ; Wed, 04 May 2016 11:20:50 -0700 (PDT) Date: Wed, 4 May 2016 20:20:49 +0200 From: Michal Hocko Subject: Re: [PATCH 12/14] mm, oom: protect !costly allocations some more Message-ID: <20160504182049.GC21490@dhcp22.suse.cz> References: <1461181647-8039-1-git-send-email-mhocko@kernel.org> <1461181647-8039-13-git-send-email-mhocko@kernel.org> <20160504060123.GB10899@js1304-P5Q-DELUXE> <20160504085307.GD29978@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Joonsoo Kim , Andrew Morton , Linus Torvalds , Johannes Weiner , Mel Gorman , David Rientjes , Tetsuo Handa , Hillf Danton , Vlastimil Babka , Linux Memory Management List , LKML On Wed 04-05-16 23:39:14, Joonsoo Kim wrote: > 2016-05-04 17:53 GMT+09:00 Michal Hocko : > > On Wed 04-05-16 15:01:24, Joonsoo Kim wrote: > >> On Wed, Apr 20, 2016 at 03:47:25PM -0400, Michal Hocko wrote: > > [...] > > > > Please try to trim your responses it makes it much easier to follow the > > discussion > > Okay. > > >> > +static inline bool > >> > +should_compact_retry(unsigned int order, enum compact_result compact_result, > >> > + enum migrate_mode *migrate_mode, > >> > + int compaction_retries) > >> > +{ > >> > + if (!order) > >> > + return false; > >> > + > >> > + /* > >> > + * compaction considers all the zone as desperately out of memory > >> > + * so it doesn't really make much sense to retry except when the > >> > + * failure could be caused by weak migration mode. > >> > + */ > >> > + if (compaction_failed(compact_result)) { > >> > >> IIUC, this compaction_failed() means that at least one zone is > >> compacted and failed. This is not same with your assumption in the > >> comment. If compaction is done and failed on ZONE_DMA, it would be > >> premature decision. > > > > Not really, because if other zones are making some progress then their > > result will override COMPACT_COMPLETE > > Think about the situation that DMA zone fails to compact and > the other zones are deferred or skipped. In this case, COMPACT_COMPLETE > will be returned as a final result and should_compact_retry() return false. > I don't think that it means all the zones are desperately out of memory. But that would mean that the ZONE_DMA would be eligible for compaction, no? And considering the watermark check this zone should COMPACT_SKIP for most allocation request. Or am I missing something? -- Michal Hocko SUSE Labs -- 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