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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 23F0BC49ED7 for ; Mon, 23 Sep 2019 05:46:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 052AA20882 for ; Mon, 23 Sep 2019 05:46:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392252AbfIWFq0 (ORCPT ); Mon, 23 Sep 2019 01:46:26 -0400 Received: from foss.arm.com ([217.140.110.172]:37348 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387559AbfIWFqZ (ORCPT ); Mon, 23 Sep 2019 01:46:25 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C5D0E142F; Sun, 22 Sep 2019 22:46:24 -0700 (PDT) Received: from [10.162.40.137] (p8cg001049571a15.blr.arm.com [10.162.40.137]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 069EC3F59C; Sun, 22 Sep 2019 22:46:21 -0700 (PDT) Subject: Re: [PATCH] mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove_memory() To: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Cc: Oscar Salvador , Michal Hocko , David Hildenbrand , Pavel Tatashin , Dan Williams References: <1568612857-10395-1-git-send-email-anshuman.khandual@arm.com> From: Anshuman Khandual Message-ID: Date: Mon, 23 Sep 2019 11:16:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1568612857-10395-1-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/16/2019 11:17 AM, Anshuman Khandual wrote: > In add_memory_resource() the memory range to be hot added first gets into > the memblock via memblock_add() before arch_add_memory() is called on it. > Reverse sequence should be followed during memory hot removal which already > is being followed in add_memory_resource() error path. This now ensures > required re-order between memblock_[free|remove]() and arch_remove_memory() > during memory hot-remove. > > Cc: Andrew Morton > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: David Hildenbrand > Cc: Pavel Tatashin > Cc: Dan Williams > Signed-off-by: Anshuman Khandual > --- > Original patch https://lkml.org/lkml/2019/9/3/327 > > Memory hot remove now works on arm64 without this because a recent commit > 60bb462fc7ad ("drivers/base/node.c: simplify unregister_memory_block_under_nodes()"). > > David mentioned that re-ordering should still make sense for consistency > purpose (removing stuff in the reverse order they were added). This patch > is now detached from arm64 hot-remove series. > > https://lkml.org/lkml/2019/9/3/326 > > mm/memory_hotplug.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index c73f09913165..355c466e0621 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1770,13 +1770,13 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size) > > /* remove memmap entry */ > firmware_map_remove(start, start + size, "System RAM"); > - memblock_free(start, size); > - memblock_remove(start, size); > > /* remove memory block devices before removing memory */ > remove_memory_block_devices(start, size); > > arch_remove_memory(nid, start, size, NULL); > + memblock_free(start, size); > + memblock_remove(start, size); > __release_memory_resource(start, size); > > try_offline_node(nid); > Hello Andrew, Any feedbacks on this, does it look okay ? - Anshuman