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 B993BC43441 for ; Fri, 16 Nov 2018 17:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87E7A20811 for ; Fri, 16 Nov 2018 17:07:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87E7A20811 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 S2390172AbeKQDVJ (ORCPT ); Fri, 16 Nov 2018 22:21:09 -0500 Received: from mx2.suse.de ([195.135.220.15]:45084 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728628AbeKQDVJ (ORCPT ); Fri, 16 Nov 2018 22:21:09 -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 1AFF5B063; Fri, 16 Nov 2018 17:07:56 +0000 (UTC) Date: Fri, 16 Nov 2018 18:07:55 +0100 From: Michal Hocko To: Wei Yang Cc: osalvador , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: use managed_zone() for more exact check in zone iteration Message-ID: <20181116170755.GN14706@dhcp22.suse.cz> References: <20181114235040.36180-1-richard.weiyang@gmail.com> <20181115133735.bb0313ec9293c415d08be550@linux-foundation.org> <20181116095720.GE14706@dhcp22.suse.cz> <1542366304.3020.15.camel@suse.de> <20181116112603.GI14706@dhcp22.suse.cz> <20181116155828.strdglxqgqe4jqkr@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116155828.strdglxqgqe4jqkr@master> 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 Fri 16-11-18 15:58:28, Wei Yang wrote: > On Fri, Nov 16, 2018 at 12:26:03PM +0100, Michal Hocko wrote: > >On Fri 16-11-18 12:05:04, osalvador wrote: > >> On Fri, 2018-11-16 at 10:57 +0100, Michal Hocko wrote: > >[...] > >> > E.g. memory hotplug decreases both managed and present counters. I > >> > am actually not sure that is 100% correct (put on my TODO list to > >> > check). There is no consistency in that regards. > >> > >> We can only offline non-reserved pages (so, managed pages). > > > >Yes > > > >> Since present pages holds reserved_pages + managed_pages, decreasing > >> both should be fine unless I am mistaken. > > > >Well, present_pages is defined as "physical pages existing within the zone" > >and those pages are still existing but they are offline. But as I've > >said I have to think about it some more > > I may not catch up with your discussions, while I'd like to share what I > learnt. > > online_pages() > online_pages_range() > zone->present_pages += onlined_pages; > > __offline_pages() > adjust_managed_page_count() > zone->present_pages -= offlined_pages; > > The two counters: present_pages & managed_pages would be adjusted during > online/offline. > > While I am not sure when *reserved_pages* would be adjusted. Will we add > this hot-added memory into memblock.reserved? and allocate memory by > memblock_alloc() after system bootup? This is not really related to this patch. I have only mentioned the memory hotplug as an example. I would rather focus on the change itself so let's not get too off topic here. -- Michal Hocko SUSE Labs