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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 5A3DDC28CF8 for ; Tue, 20 Nov 2018 15:34:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 295A620831 for ; Tue, 20 Nov 2018 15:34:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 295A620831 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com 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 S1727297AbeKUCEU (ORCPT ); Tue, 20 Nov 2018 21:04:20 -0500 Received: from smtp.nue.novell.com ([195.135.221.5]:35797 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725851AbeKUCEU (ORCPT ); Tue, 20 Nov 2018 21:04:20 -0500 Received: from emea4-mta.ukb.novell.com ([10.120.13.87]) by smtp.nue.novell.com with ESMTP (TLS encrypted); Tue, 20 Nov 2018 16:34:36 +0100 Received: from [149.44.172.157] (nwb-a10-snat.microfocus.com [10.120.13.201]) by emea4-mta.ukb.novell.com with ESMTP (TLS encrypted); Tue, 20 Nov 2018 15:13:52 +0000 Message-ID: <1542726815.6817.8.camel@suse.com> Subject: Re: [RFC PATCH 2/3] mm, memory_hotplug: deobfuscate migration part of offlining From: osalvador To: Michal Hocko , linux-mm@kvack.org Cc: Andrew Morton , Pavel Tatashin , David Hildenbrand , LKML , Michal Hocko Date: Tue, 20 Nov 2018 16:13:35 +0100 In-Reply-To: <20181120134323.13007-3-mhocko@kernel.org> References: <20181120134323.13007-1-mhocko@kernel.org> <20181120134323.13007-3-mhocko@kernel.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Signed-off-by: Michal Hocko [...] > + do { > + for (pfn = start_pfn; pfn;) > + { > + /* start memory hot removal */ Should we change thAT comment? I mean, this is not really the hot- removal stage. Maybe "start memory migration" suits better? or memory offlining? > + ret = -EINTR; > + if (signal_pending(current)) { > + reason = "signal backoff"; > + goto failed_removal_isolated; > + } > > - cond_resched(); > - lru_add_drain_all(); > - drain_all_pages(zone); > + cond_resched(); > + lru_add_drain_all(); > + drain_all_pages(zone); > > - pfn = scan_movable_pages(start_pfn, end_pfn); > - if (pfn) { /* We have movable pages */ > - ret = do_migrate_range(pfn, end_pfn); > - goto repeat; > - } > + pfn = scan_movable_pages(pfn, end_pfn); > + if (pfn) { > + /* TODO fatal migration failures > should bail out */ > + do_migrate_range(pfn, end_pfn); > + } > + } > + > + /* > + * dissolve free hugepages in the memory block > before doing offlining > + * actually in order to make hugetlbfs's object > counting consistent. > + */ > + ret = dissolve_free_huge_pages(start_pfn, end_pfn); > + if (ret) { > + reason = "failure to dissolve huge pages"; > + goto failed_removal_isolated; > + } > + /* check again */ > + offlined_pages = check_pages_isolated(start_pfn, > end_pfn); > + } while (offlined_pages < 0); > > - /* > - * dissolve free hugepages in the memory block before doing > offlining > - * actually in order to make hugetlbfs's object counting > consistent. > - */ > - ret = dissolve_free_huge_pages(start_pfn, end_pfn); > - if (ret) { > - reason = "failure to dissolve huge pages"; > - goto failed_removal_isolated; > - } > - /* check again */ > - offlined_pages = check_pages_isolated(start_pfn, end_pfn); > - if (offlined_pages < 0) > - goto repeat; This indeed looks much nicer and it is easier to follow. With the changes commented by David: Reviewed-by: Oscar Salvador