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 28598C4360F for ; Tue, 12 Mar 2019 15:57:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFA912147C for ; Tue, 12 Mar 2019 15:57:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552406254; bh=uFGF56FNDC++i8l3obPT4y6Bwd0/w+W7yiW6upID07w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=J+KUJeJgnd3zHd6/CVo7Yju/wERQ4JVnRyhVx2ajR9ERYszfxaq6+U/3KbIqCpLdO tumWdDdlAv65Cbn4BSqfTzPGiqAh9qwoXZJWH+7ex4EcpU50kZlyg0uNGMU1AyDsF3 5qDsOb7szM+ByY/gcqKEy7QUivd0ls2cRmAkcm34= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726612AbfCLP5c (ORCPT ); Tue, 12 Mar 2019 11:57:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:48552 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726272AbfCLP5c (ORCPT ); Tue, 12 Mar 2019 11:57:32 -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 2DB6EAC5F; Tue, 12 Mar 2019 15:57:31 +0000 (UTC) Date: Tue, 12 Mar 2019 16:57:30 +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: [RESEND PATCH] mm/hotplug: don't reset pagetype flags for offline Message-ID: <20190312155730.GZ5721@dhcp22.suse.cz> References: <20190310200102.88014-1-cai@lca.pw> <20190312153458.qvmrblg3pnokgx4d@d104.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190312153458.qvmrblg3pnokgx4d@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 Tue 12-03-19 16:35:06, Oscar Salvador wrote: [...] > One thing I noticed when looking at start_isolate_page_range and > undo_isolate_page_range functions, is that start_isolate_page_range increments > the number of isolated pageblocks, while undo_isolate_page_range does the counter > part. > Since undo_isolate_page_range is really never called during offlining, > we leave zone->nr_isolate_pageblock with a stale value. > > I __think__ this does not matter much. > We only get to check whether a zone got isolated pageblocks in > has_isolate_pageblock(), and this is called from: > > free_one_page > free_pcppages_bulk > __free_one_page It forces those into slow(er) path. So it makes a difference. > With a quick glance, the only difference in has_isolate_pageblock() returning > true or false, seems to be that those functions perform some extra checks in > case the zone reports to have isolated pageblocks. > > I wonder if we should set nr_isolate_pageblock back to its original value > before start_isolate_page_range. Yes. And that would be a fixup to my 2ce13640b3f4. -- Michal Hocko SUSE Labs