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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 8BC07ECDFB3 for ; Tue, 17 Jul 2018 14:24:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D8032064D for ; Tue, 17 Jul 2018 14:24:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4D8032064D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 S1731957AbeGQO5r (ORCPT ); Tue, 17 Jul 2018 10:57:47 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58260 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731679AbeGQO5r (ORCPT ); Tue, 17 Jul 2018 10:57:47 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3E4E1401EF05; Tue, 17 Jul 2018 14:24:52 +0000 (UTC) Received: from localhost (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8A6092026D68; Tue, 17 Jul 2018 14:24:49 +0000 (UTC) Date: Tue, 17 Jul 2018 22:24:43 +0800 From: Baoquan He To: Michal Hocko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, corbet@lwn.net, linux-doc@vger.kernel.org Subject: Re: [PATCH] mm/page_alloc: Deprecate kernelcore=nn and movable_core= Message-ID: <20180717142443.GG1724@MiWiFi-R3L-srv> References: <20180717131837.18411-1-bhe@redhat.com> <20180717133109.GI7193@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180717133109.GI7193@dhcp22.suse.cz> User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Tue, 17 Jul 2018 14:24:52 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Tue, 17 Jul 2018 14:24:52 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'bhe@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Michal, On 07/17/18 at 03:31pm, Michal Hocko wrote: > On Tue 17-07-18 21:18:37, Baoquan He wrote: > > We can still use 'kernelcore=mirror' or 'movable_node' for the usage > > of hotplug and movable zone. If somebody shows up with a valid usecase > > we can reconsider. > > Well this doesn't really explain why to deprecate this functionality. > It is a rather ugly hack that has been originally introduced for large > order allocations. But we do have compaction these days. Even though the > compaction cannot solve all the fragmentation issues the zone movable is > not a great answer as it introduces other issues (basically highmem kind > of issues we used to have on 32b systems). > The current code doesn't work with KASLR and the code is too subtle to > work properly in other cases as well. E.g. movablecore range might cover > already used memory (e.g. bootmem allocations) and therefore it doesn't > comply with the basic assumption that the memory is movable and that > confuses memory hotplug (e.g. 15c30bc09085 ("mm, memory_hotplug: make > has_unmovable_pages more robust"). > > There are probably other issues I am not aware of but primarily the code > adds a maintenance burden which would be better to get rid of. > > I would also go further and remove all the code the feature is using at > one go. If somebody really needs this functionality we would need to > revert the whole thing anyway. Thanks for these details. I can arrange your above saying and rewrite patch log. Are you suggesting removing the code "kernelcore=nn" and "movablecore=" are using? If yes, I can repost with these changes. Just saw some deprecated codes are still there for future cleaning up. So posted this v1 patch. Thanks Baoquan > > --- > > Documentation/admin-guide/kernel-parameters.txt | 2 ++ > > mm/page_alloc.c | 3 +++ > > 2 files changed, 5 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index efc7aa7a0670..1e22c49866a2 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -1855,6 +1855,7 @@ > > keepinitrd [HW,ARM] > > > > kernelcore= [KNL,X86,IA-64,PPC] > > + [Usage of kernelcore=nn[KMGTPE] | nn% is deprecated] > > Format: nn[KMGTPE] | nn% | "mirror" > > This parameter specifies the amount of memory usable by > > the kernel for non-movable allocations. The requested > > @@ -2395,6 +2396,7 @@ > > reporting absolute coordinates, such as tablets > > > > movablecore= [KNL,X86,IA-64,PPC] > > + [Deprecated] > > Format: nn[KMGTPE] | nn% > > This parameter is the complement to kernelcore=, it > > specifies the amount of memory used for migratable > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 1521100f1e63..86cf05f48b5f 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -6899,6 +6899,8 @@ static int __init cmdline_parse_kernelcore(char *p) > > return 0; > > } > > > > + pr_warn("Only kernelcore=mirror supported, " > > + "usage of kernelcore=nn[KMGTPE]|nn%% is deprecated.\n"); > > return cmdline_parse_core(p, &required_kernelcore, > > &required_kernelcore_percent); > > } > > @@ -6909,6 +6911,7 @@ static int __init cmdline_parse_kernelcore(char *p) > > */ > > static int __init cmdline_parse_movablecore(char *p) > > { > > + pr_warn("Option movablecore= is deprecated.\n"); > > return cmdline_parse_core(p, &required_movablecore, > > &required_movablecore_percent); > > } > > -- > > 2.13.6 > > -- > Michal Hocko > SUSE Labs