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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 E3C42C71156 for ; Wed, 2 Dec 2020 06:44:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AA0722203 for ; Wed, 2 Dec 2020 06:44:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728652AbgLBGo6 (ORCPT ); Wed, 2 Dec 2020 01:44:58 -0500 Received: from foss.arm.com ([217.140.110.172]:59208 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728212AbgLBGo6 (ORCPT ); Wed, 2 Dec 2020 01:44:58 -0500 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 7D93530E; Tue, 1 Dec 2020 22:44:12 -0800 (PST) Received: from [10.163.83.48] (unknown [10.163.83.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F3E8B3F718; Tue, 1 Dec 2020 22:44:07 -0800 (PST) Subject: Re: [RFC V2 0/3] mm/hotplug: Pre-validate the address range with platform To: linux-mm@kvack.org, akpm@linux-foundation.org, david@redhat.com Cc: linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland References: <1606706992-26656-1-git-send-email-anshuman.khandual@arm.com> From: Anshuman Khandual Message-ID: <7ffb5199-1b39-3f35-32cd-b59f71cc00c5@arm.com> Date: Wed, 2 Dec 2020 12:14:04 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1606706992-26656-1-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/30/20 8:59 AM, Anshuman Khandual wrote: > This series adds a mechanism allowing platforms to weigh in and prevalidate > incoming address range before proceeding further with the memory hotplug. > This helps prevent potential platform errors for the given address range, > down the hotplug call chain, which inevitably fails the hotplug itself. > > This mechanism was suggested by David Hildenbrand during another discussion > with respect to a memory hotplug fix on arm64 platform. > > https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/ > > This mechanism focuses on the addressibility aspect and not [sub] section > alignment aspect. Hence check_hotplug_memory_range() and check_pfn_span() > have been left unchanged. Wondering if all these can still be unified in > an expanded memhp_range_allowed() check, that can be called from multiple > memory hot add and remove paths. > > This series applies on v5.10-rc6 and has been slightly tested on arm64. > But looking for some early feedback here. > > Changes in RFC V2: > > Incorporated all review feedbacks from David. > > - Added additional range check in __segment_load() on s390 which was lost > - Changed is_private init in pagemap_range() > - Moved the framework into mm/memory_hotplug.c > - Made arch_get_addressable_range() a __weak function > - Renamed arch_get_addressable_range() as arch_get_mappable_range() > - Callback arch_get_mappable_range() only handles range requiring linear mapping > - Merged multiple memhp_range_allowed() checks in register_memory_resource() > - Replaced WARN() with pr_warn() in memhp_range_allowed() > - Replaced error return code ERANGE with E2BIG There is one build failure with MEMORY_HOTPLUG=y and MEMORY_HOTREMOVE=n. There are warnings on arm64 and s390 platforms when built with W=1 due to lack of prototypes required with -Wmissing-prototypes. I have fixed all these problems for the next iteration when there is broad agreement on the overall approach.