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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 8C39FC10F13 for ; Tue, 16 Apr 2019 09:52:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 62E5121773 for ; Tue, 16 Apr 2019 09:52:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728771AbfDPJwg (ORCPT ); Tue, 16 Apr 2019 05:52:36 -0400 Received: from foss.arm.com ([217.140.101.70]:51048 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726739AbfDPJwg (ORCPT ); Tue, 16 Apr 2019 05:52:36 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DEEE380D; Tue, 16 Apr 2019 02:52:35 -0700 (PDT) Received: from [10.162.42.238] (p8cg001049571a15.blr.arm.com [10.162.42.238]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA29A3F68F; Tue, 16 Apr 2019 02:52:29 -0700 (PDT) Subject: Re: [PATCH V2 2/2] arm64/mm: Enable memory hot remove To: David Hildenbrand , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, akpm@linux-foundation.org, will.deacon@arm.com, catalin.marinas@arm.com Cc: mhocko@suse.com, mgorman@techsingularity.net, james.morse@arm.com, mark.rutland@arm.com, robin.murphy@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, osalvador@suse.de, cai@lca.pw, logang@deltatee.com, ira.weiny@intel.com References: <1555221553-18845-1-git-send-email-anshuman.khandual@arm.com> <1555221553-18845-3-git-send-email-anshuman.khandual@arm.com> <614fe7d2-cc5d-61a2-6894-026e30498269@redhat.com> From: Anshuman Khandual Message-ID: Date: Tue, 16 Apr 2019 15:22:28 +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: <614fe7d2-cc5d-61a2-6894-026e30498269@redhat.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 04/15/2019 07:25 PM, David Hildenbrand wrote: >> + >> +#ifdef CONFIG_MEMORY_HOTREMOVE >> +int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap) >> +{ >> + unsigned long start_pfn = start >> PAGE_SHIFT; >> + unsigned long nr_pages = size >> PAGE_SHIFT; >> + struct zone *zone = page_zone(pfn_to_page(start_pfn)); >> + int ret; >> + >> + ret = __remove_pages(zone, start_pfn, nr_pages, altmap); >> + if (!ret) > Please note that I posted patches that remove all error handling > from arch_remove_memory and __remove_pages(). They are already in next/master > > So this gets a lot simpler and more predictable. > > > Author: David Hildenbrand > Date: Wed Apr 10 11:02:27 2019 +1000 > > mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail > > All callers of arch_remove_memory() ignore errors. And we should really > try to remove any errors from the memory removal path. No more errors are > reported from __remove_pages(). BUG() in s390x code in case > arch_remove_memory() is triggered. We may implement that properly later. > WARN in case powerpc code failed to remove the section mapping, which is > better than ignoring the error completely right now Sure will follow suit next time around.