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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 32E65C43381 for ; Wed, 13 Mar 2019 08:01:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F388A2173C for ; Wed, 13 Mar 2019 08:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552464070; bh=2TDmEoCcgHMKSbjT/SIgwVVG4CmX4DKwmv6SgL5W9vs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KJkuvJ0/wmOuMuhonJz1qlI90JJJgtIax7AMOpAc58KVChAjRZDEe1hddHvOoFLT6 h3E3sSI9pEudA7T9n0gWZ0mfgRaSwhjDgcKUKO1eehiNHiypjUECYVQ91BfUk9Noln nr9CNbwd4kFEBA5HFxptl0pVNoH5PyP6SbNZdxVQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727070AbfCMIBH (ORCPT ); Wed, 13 Mar 2019 04:01:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:56254 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726539AbfCMIBH (ORCPT ); Wed, 13 Mar 2019 04:01:07 -0400 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 EE063AE84; Wed, 13 Mar 2019 08:01:05 +0000 (UTC) Date: Wed, 13 Mar 2019 09:01:05 +0100 From: Michal Hocko To: Oscar Salvador Cc: Qian Cai , akpm@linux-foundation.org, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/hotplug: fix offline undo_isolate_page_range() Message-ID: <20190313080105.GG5721@dhcp22.suse.cz> References: <20190313014216.36782-1-cai@lca.pw> <20190313075212.wc3pbwixx3ppwxua@d104.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190313075212.wc3pbwixx3ppwxua@d104.suse.de> 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 Wed 13-03-19 08:52:16, Oscar Salvador wrote: > On Tue, Mar 12, 2019 at 09:42:16PM -0400, Qian Cai wrote: > > + > > + /* > > + * Onlining will reset pagetype flags and makes migrate type > > + * MOVABLE, so just need to decrease the number of isolated > > + * pageblocks zone counter here. > > + */ > > + for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { > > + int i; > > + > > + for (i = 0; i < pageblock_nr_pages; i++) > > + if (pfn_valid_within(pfn + i)) { > > + zone->nr_isolate_pageblock--; > > + break; > > + } > > + } > > + > > I do not really like this. > > I first thought about saving the value before entering start_isolate_page_range, > but that could race with alloc_contig_range for instance. Yup. We need to take the zone lock. > So, why not make start_isolate_page_range to return the actual number of isolated > pageblocks? That makes more sense indeed. -- Michal Hocko SUSE Labs