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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 0D190C432C1 for ; Wed, 25 Sep 2019 03:50:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CA4672075D for ; Wed, 25 Sep 2019 03:50:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA4672075D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 451F36B0269; Tue, 24 Sep 2019 23:50:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4029B6B026B; Tue, 24 Sep 2019 23:50:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 318F76B026C; Tue, 24 Sep 2019 23:50:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0020.hostedemail.com [216.40.44.20]) by kanga.kvack.org (Postfix) with ESMTP id 1003B6B0269 for ; Tue, 24 Sep 2019 23:50:33 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 9BFED824CA3D for ; Wed, 25 Sep 2019 03:50:32 +0000 (UTC) X-FDA: 75972065904.15.blade53_3e9d46066694d X-HE-Tag: blade53_3e9d46066694d X-Filterd-Recvd-Size: 3991 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Sep 2019 03:50:30 +0000 (UTC) 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 3743C1570; Tue, 24 Sep 2019 20:50:29 -0700 (PDT) Received: from [10.162.41.120] (p8cg001049571a15.blr.arm.com [10.162.41.120]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 06B0F3F694; Tue, 24 Sep 2019 20:50:26 -0700 (PDT) Subject: Re: [PATCH] mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove_memory() To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador , Michal Hocko , David Hildenbrand , Pavel Tatashin , Dan Williams References: <1568612857-10395-1-git-send-email-anshuman.khandual@arm.com> <20190924201335.0af280458bf68d7f57acb637@linux-foundation.org> From: Anshuman Khandual Message-ID: <9262a7bf-72d9-e23a-a8a3-4f026ee2e4a2@arm.com> Date: Wed, 25 Sep 2019 09:20:44 +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: <20190924201335.0af280458bf68d7f57acb637@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 09/25/2019 08:43 AM, Andrew Morton wrote: > On Mon, 23 Sep 2019 11:16:38 +0530 Anshuman Khandual wrote: > >> >> >> 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 >> >> ... >> >> Hello Andrew, >> >> Any feedbacks on this, does it look okay ? >> > > Well. I'd parked this for 5.4-rc1 processing because it looked like a > cleanup. This does not fix a serious problem. It just removes an inconsistency while freeing resources during memory hot remove which for now does not pose a real problem. > > But waaaay down below the ^---$ line I see "Memory hot remove now works > on arm64". Am I correct in believing that 60bb462fc7ad broke arm64 mem > hot remove? And that this patch fixes a serious regression? If so, No. [Proposed] arm64 memory hot remove series does not anymore depend on this particular patch because 60bb462fc7ad has already solved the problem. > that should have been right there in the patch title and changelog! V2 (https://patchwork.kernel.org/patch/11159939/) for this patch makes it very clear in it's commit message. - Anshuman