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=-7.5 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=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 CDCCDC433E6 for ; Thu, 25 Mar 2021 16:21:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A004861A2B for ; Thu, 25 Mar 2021 16:21:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229929AbhCYQUx (ORCPT ); Thu, 25 Mar 2021 12:20:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:36603 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229812AbhCYQUc (ORCPT ); Thu, 25 Mar 2021 12:20:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616689232; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UUaI0jPAJHBsBAO60IzxWqFDvl762DqvoYKPg8yydHk=; b=GuXJOw46kZdaEjeUhusiSRnRVjoQTs3AFLbCAC2esPVQCCYtCjZHgU8flDNJ6NUD19lJzW 4+ilIVLpWs8n0o9K57CSNTYQmCWcEodKrI53EiZZN1SRBO+eh3WqppcQFLIL1EvLrZdxaD ouSLeXruO2jWUedRcp8DakGPGDcjrik= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-62-Pj8XVcylP5aLUVpJlF9LtQ-1; Thu, 25 Mar 2021 12:20:28 -0400 X-MC-Unique: Pj8XVcylP5aLUVpJlF9LtQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EF61E108BD0B; Thu, 25 Mar 2021 16:20:26 +0000 (UTC) Received: from [10.36.115.72] (ovpn-115-72.ams2.redhat.com [10.36.115.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id 18E2B5D736; Thu, 25 Mar 2021 16:20:24 +0000 (UTC) To: Michal Hocko Cc: Oscar Salvador , Andrew Morton , Anshuman Khandual , Vlastimil Babka , Pavel Tatashin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <31110e58-c99a-8dee-6f6e-98f456b77759@redhat.com> <062bc5d7-a83c-1c1a-7b77-9f043643f4fa@redhat.com> <31c3e6f7-f631-7b00-2c33-518b0f24a75f@redhat.com> <40fac999-2d28-9205-23f0-516fa9342bbe@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range Message-ID: <92fe19d0-56ac-e929-a9c1-d6a4e0da39d1@redhat.com> Date: Thu, 25 Mar 2021 17:20:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25.03.21 17:07, Michal Hocko wrote: > On Thu 25-03-21 16:35:58, Michal Hocko wrote: > [...] >> So there is indeed a difference. One way around that would be to mark >> vmemmap pages (e.g. PageReserved && magic value stored somewhere in the >> struct page - resembling bootmem vmemmaps) or mark section fully backing >> vmemmaps as online (ugly). > > I am not yet ready to give up on this. Here is a quick stab at the > pfn_to_online_page approach. It is not great but it is not really > terrible either. I think we can do better and skip We both seem to have a different taste, to phrase it in a nice way :) ; but well, you seem to have set your mind (just like I seem to have set mine when trying to find a nice and somewhat-clean way to handle this when discussing it in the past). I expressed my opinion, shared my findings and expressed my concerns; the series has my RB and the discussion here is around something I consider in no way better than what we have right now. I'll let Oscar handle discussing this topic further (sorry Oscar! :) ), but I'll happily review what the outcome of that will be. -- Thanks, David / dhildenb