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 699A3ECDFB3 for ; Mon, 16 Jul 2018 15:24:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 233AD208AD for ; Mon, 16 Jul 2018 15:24:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 233AD208AD 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 S1730093AbeGPPwJ (ORCPT ); Mon, 16 Jul 2018 11:52:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:38438 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727610AbeGPPwI (ORCPT ); Mon, 16 Jul 2018 11:52:08 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2E9F1AEC0; Mon, 16 Jul 2018 15:24:12 +0000 (UTC) Date: Mon, 16 Jul 2018 17:24:10 +0200 From: Michal Hocko To: Baoquan He Cc: Chao Fan , Dou Liyang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, yasu.isimatu@gmail.com, keescook@chromium.org, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com, vbabka@suse.cz, mgorman@techsingularity.net Subject: Re: Bug report about KASLR and ZONE_MOVABLE Message-ID: <20180716152410.GU17280@dhcp22.suse.cz> References: <20180711094244.GA2019@localhost.localdomain> <20180711104158.GE2070@MiWiFi-R3L-srv> <20180711104944.GG1969@MiWiFi-R3L-srv> <20180711124008.GF2070@MiWiFi-R3L-srv> <72721138-ba6a-32c9-3489-f2060f40a4c9@cn.fujitsu.com> <20180712060115.GD6742@localhost.localdomain> <20180712123228.GK32648@dhcp22.suse.cz> <20180712235240.GH2070@MiWiFi-R3L-srv> <20180716113845.GM17280@dhcp22.suse.cz> <20180716130202.GB1724@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180716130202.GB1724@MiWiFi-R3L-srv> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 16-07-18 21:02:02, Baoquan He wrote: > On 07/16/18 at 01:38pm, Michal Hocko wrote: > > On Fri 13-07-18 07:52:40, Baoquan He wrote: > > > Hi Michal, > > > > > > On 07/12/18 at 02:32pm, Michal Hocko wrote: > > [...] > > > > I am not able to find the beginning of the email thread right now. Could > > > > you summarize what is the actual problem please? > > > > > > The bug is found on x86 now. > > > > > > When added "kernelcore=" or "movablecore=" into kernel command line, > > > kernel memory is spread evenly among nodes. However, this is right when > > > KASLR is not enabled, then kernel will be at 16M of place in x86 arch. > > > If KASLR enabled, it could be put any place from 16M to 64T randomly. > > > > > > Consider a scenario, we have 10 nodes, and each node has 20G memory, and > > > we specify "kernelcore=50%", means each node will take 10G for > > > kernelcore, 10G for movable area. But this doesn't take kernel position > > > into consideration. E.g if kernel is put at 15G of 2nd node, namely > > > node1. Then we think on node1 there's 10G for kernelcore, 10G for > > > movable, in fact there's only 5G available for movable, just after > > > kernel. > > > > OK, I guess I see that part. But who is going to use movablecore along > > with KASLR enabled? I mean do we really have to support those two > > obscure command line parameters for KASLR? > > Not very sure whether we have to support both of those to work with > KASLR. Maybe it's time to make clear of it now. Yes, I would really like to deprecate this. It is an ugly piece of code and it's far from easily maintainable as well. > For 'kernelcore=mirror', we have solved the conflict to make it work well > with KASLR. For 'movable_node' conflict with KASLR, Chao is posting > patches to fix it. As for 'kernelcore=' and 'movablecore=', > > 1) solve the conflict between them with KASLR in > find_zone_movable_pfns_for_nodes(); > 2) disable KASLR when 'kernelcore=' | 'movablecore=' is set; > 3) disable 'kernelcore=' | 'movablecore=' when KASLR is enabled; > 4) add note in doc to notice people to not add them at the same time; I would simply warn that those kernel parameters are not supported anymore. If somebody shows up with a valid usecase we can reconsider. > 2) and 3) may need be fixed in arch/x86 code. As long as come to an > agreement, any one is fine to me. > > > > In fact I would be much more concerned about memory hotplug and > > pre-defined movable nodes. Does the current KASLR code work in that > > case? > > As said above, kernelcore=mirror works well with KASLR now. Making > 'movable_node' work with KASLR is in progress. OK, thanks for the info. -- Michal Hocko SUSE Labs