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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 1E439C43441 for ; Fri, 16 Nov 2018 11:05:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B906E208E3 for ; Fri, 16 Nov 2018 11:05:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B906E208E3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de 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 S2389548AbeKPVRN (ORCPT ); Fri, 16 Nov 2018 16:17:13 -0500 Received: from mx2.suse.de ([195.135.220.15]:57570 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727630AbeKPVRN (ORCPT ); Fri, 16 Nov 2018 16:17:13 -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 83ABBAF14; Fri, 16 Nov 2018 11:05:20 +0000 (UTC) Message-ID: <1542366304.3020.15.camel@suse.de> Subject: Re: [PATCH] mm: use managed_zone() for more exact check in zone iteration From: osalvador To: Michal Hocko , Andrew Morton Cc: Wei Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Fri, 16 Nov 2018 12:05:04 +0100 In-Reply-To: <20181116095720.GE14706@dhcp22.suse.cz> References: <20181114235040.36180-1-richard.weiyang@gmail.com> <20181115133735.bb0313ec9293c415d08be550@linux-foundation.org> <20181116095720.GE14706@dhcp22.suse.cz> 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 On Fri, 2018-11-16 at 10:57 +0100, Michal Hocko wrote: > On Thu 15-11-18 13:37:35, Andrew Morton wrote: > [...] > > Worse, the situations in which managed_zone() != populated_zone() > > are > > rare(?), so it will take a long time for problems to be discovered, > > I > > expect. > > We would basically have to deplete the whole zone by the bootmem > allocator or pull out all pages from the page allocator. 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). Since present pages holds reserved_pages + managed_pages, decreasing both should be fine unless I am mistaken. Oscar Salvador