From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 218BCC32789 for ; Tue, 6 Nov 2018 08:28:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6FEF20866 for ; Tue, 6 Nov 2018 08:28:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6FEF20866 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730010AbeKFRwd (ORCPT ); Tue, 6 Nov 2018 12:52:33 -0500 Received: from mx2.suse.de ([195.135.220.15]:59714 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728133AbeKFRwd (ORCPT ); Tue, 6 Nov 2018 12:52:33 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5C783ACA9; Tue, 6 Nov 2018 08:28:27 +0000 (UTC) Date: Tue, 6 Nov 2018 09:28:26 +0100 From: Michal Hocko To: Baoquan He Cc: Andrew Morton , linux-mm@kvack.org, LKML , Stable tree Subject: Re: [PATCH] mm, memory_hotplug: teach has_unmovable_pages about of LRU migrateable pages Message-ID: <20181106082826.GC27423@dhcp22.suse.cz> References: <20181101091055.GA15166@MiWiFi-R3L-srv> <20181102155528.20358-1-mhocko@kernel.org> <20181105002009.GF27491@MiWiFi-R3L-srv> <20181105091407.GB4361@dhcp22.suse.cz> <20181105092851.GD4361@dhcp22.suse.cz> <20181105102520.GB22011@MiWiFi-R3L-srv> <20181105123837.GH4361@dhcp22.suse.cz> <20181105142308.GJ27491@MiWiFi-R3L-srv> <20181105171002.GO4361@dhcp22.suse.cz> <20181106002216.GK27491@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181106002216.GK27491@MiWiFi-R3L-srv> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 06-11-18 08:22:16, Baoquan He wrote: > On 11/05/18 at 06:10pm, Michal Hocko wrote: > > On Mon 05-11-18 22:23:08, Baoquan He wrote: > > > On 11/05/18 at 01:38pm, Michal Hocko wrote: > > > > On Mon 05-11-18 18:25:20, Baoquan He wrote: > > > > > Hi Michal, > > > > > > > > > > On 11/05/18 at 10:28am, Michal Hocko wrote: > > > > > > > > > > > > Or something like this. Ugly as hell, no question about that. I also > > > > > > have to think about this some more to convince myself this will not > > > > > > result in an endless loop under some situations. > > > > > > > > > > It failed. Paste the log and patch diff here, please help check if I made > > > > > any mistake on manual code change. The log is at bottom. > > > > > > > > The retry patch is obviously still racy, it just makes the race window > > > > slightly smaller and I hoped it would catch most of those races but this > > > > is obviously not the case. > > > > > > > > I was thinking about your MIGRATE_MOVABLE check some more and I still do > > > > not like it much, we just change migrate type at many places and I have > > > > hard time to actually see this is always safe wrt. to what we need here. > > > > > > > > We should be able to restore the zone type check though. The > > > > primary problem fixed by 15c30bc09085 ("mm, memory_hotplug: make > > > > has_unmovable_pages more robust") was that early allocations made it to > > > > the zone_movable range. If we add the check _after_ the PageReserved() > > > > check then we should be able to rule all bootmem allocation out. > > > > > > > > So what about the following (on top of the previous patch which makes > > > > sense on its own I believe). > > > > > > Yes, I think this looks very reasonable and should be robust. > > > > > > Have tested it, hot removing 4 hotpluggable nodes continusously > > > succeeds, and then hot adding them back, still works well. > > > > > > So please feel free to add my Tested-by or Acked-by. > > > > > > Tested-by: Baoquan He > > > or > > > Acked-by: Baoquan He > > > > Thanks for retesting! Does this apply to both patches? > > Sorry, don't get it. I just applied this on top of linus's tree and > tested. Do you mean applying it on top of previous code change? Yes. While the first patch will obviously not help for movable zone because the movable check will override any later check it seems still useful to reduce false positives on normal zones. Or do you think this is not worth it? -- Michal Hocko SUSE Labs