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_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 BCEAEC3A5A4 for ; Fri, 30 Aug 2019 08:31:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8ED5F2377D for ; Fri, 30 Aug 2019 08:31:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567153899; bh=tyTk3IIgvGDJTpsIJUhA5X+AF9/OKS6VWDIx6qMarAw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=tuJQNjtrWNJzJtFsVTYA2VeyLwtmo33xCYJKxdWk86lOgS6e8QeFzcLtb6FlvCytt uqPYLpi57MrooPKXIAOGPTLyZWZeumXigRKd5jxYc9a4nd4DqAh2wEgIj3hRTNW9r0 ACd+Le18ajZRLHmqIGsZmhaLCe+blGAN0brf/2dE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727891AbfH3Ibi (ORCPT ); Fri, 30 Aug 2019 04:31:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:47956 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726495AbfH3Ibi (ORCPT ); Fri, 30 Aug 2019 04:31:38 -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 9BD1AAF47; Fri, 30 Aug 2019 08:31:36 +0000 (UTC) Date: Fri, 30 Aug 2019 10:31:35 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Oscar Salvador , Pavel Tatashin , Dan Williams , Wei Yang Subject: Re: [PATCH v2 3/6] mm/memory_hotplug: Process all zones when removing memory Message-ID: <20190830083135.GU28313@dhcp22.suse.cz> References: <20190826101012.10575-1-david@redhat.com> <20190826101012.10575-4-david@redhat.com> <20190829153936.GJ28313@dhcp22.suse.cz> <20190829162704.GL28313@dhcp22.suse.cz> <20190830060100.GP28313@dhcp22.suse.cz> <18aed12d-0611-7d35-2994-075d09269513@redhat.com> <20190830064724.GT28313@dhcp22.suse.cz> <17de8d65-592f-72be-0891-6eaaedfd26f2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17de8d65-592f-72be-0891-6eaaedfd26f2@redhat.com> 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 30-08-19 09:07:59, David Hildenbrand wrote: > On 30.08.19 08:47, Michal Hocko wrote: > > On Fri 30-08-19 08:20:32, David Hildenbrand wrote: > > [...] > >> Regarding shrink_zone_span(), I suspect it was introduced by > >> > >> d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug") > > > > zone shrinking code is much older - 815121d2b5cd5. But I do not think > > this is really needed for Fixes tag. > > > > Yes it's older, but since d0dc12e86b31 we could run into uninitialized > nids for added memory when trying to shrink the zone. Well, not really. Strictly speaking pre d0dc12e86b31 would initialize struct page to zero so it is initialized but that doesn't mean that the struct page has a meaningfull and usable content. Zone index would be 0 so the lowest zone which is not something you want to use on the hotremove path. -- Michal Hocko SUSE Labs