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=-8.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 6CD0DC43461 for ; Thu, 10 Sep 2020 14:35:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D03A2076D for ; Thu, 10 Sep 2020 14:35:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="a5q9s+HU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731156AbgIJOfR (ORCPT ); Thu, 10 Sep 2020 10:35:17 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:27229 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731031AbgIJObo (ORCPT ); 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Thu, 10 Sep 2020 13:57:17 +0000 (UTC) Received: from [10.36.113.88] (ovpn-113-88.ams2.redhat.com [10.36.113.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7AB965C629; Thu, 10 Sep 2020 13:57:15 +0000 (UTC) Subject: Re: [PATCH] mm: don't rely on system state to detect hot-plug operations To: Michal Hocko Cc: Oscar Salvador , Laurent Dufour , akpm@linux-foundation.org, rafael@kernel.org, nathanl@linux.ibm.com, cheloha@linux.ibm.com, stable@vger.kernel.org, Greg Kroah-Hartman , linux-mm@kvack.org, LKML References: <4cdb54be-1a92-4ba4-6fee-3b415f3468a9@linux.ibm.com> <20200909105914.GF7348@dhcp22.suse.cz> <74a62b00-235e-7deb-2814-f3b240fea25e@linux.ibm.com> <20200910072331.GB28354@dhcp22.suse.cz> <31cfdf35-618f-6f56-ef16-0d999682ad02@linux.ibm.com> <20200910111246.GE28354@dhcp22.suse.cz> <20200910120343.GA6635@linux> <20200910124755.GG28354@dhcp22.suse.cz> <27e73d7d-c172-aa84-dad2-f97ed6123db4@redhat.com> <20200910135404.GJ28354@dhcp22.suse.cz> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200910135404.GJ28354@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> Also, under QEMU, just do a reboot with hotplugged memory and you're in >> the very same situation. > > OK, I didn't know that. I thought the memory would be presented as a > normal memory after reboot. Thanks for the clarification. That's one of the cases where QEMU differs to actual hardware - it's not added to e820, so ACPI always probes+detects+adds DIMMs during boot. Some people (me :)) consider that a feature and not a BUG. -- Thanks, David / dhildenb