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 E7353C433DB for ; Thu, 25 Mar 2021 14:09:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7FA3A61A23 for ; Thu, 25 Mar 2021 14:09:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7FA3A61A23 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF7EE6B0073; Thu, 25 Mar 2021 10:09:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EA7956B0074; Thu, 25 Mar 2021 10:09:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D48256B0075; Thu, 25 Mar 2021 10:09:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0030.hostedemail.com [216.40.44.30]) by kanga.kvack.org (Postfix) with ESMTP id AE0636B0073 for ; Thu, 25 Mar 2021 10:09:58 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 5CF8729DE3 for ; Thu, 25 Mar 2021 14:09:58 +0000 (UTC) X-FDA: 77958580476.11.A5EBEC3 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf22.hostedemail.com (Postfix) with ESMTP id 13F8AC0007D4 for ; Thu, 25 Mar 2021 14:09:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616681384; 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=ByfSI5VQlkUqIXhFO5RAp8f/3O7Cm7NtKxYn964lR8s=; b=Qkn6STlhqshY7KpU0ir8SMoAEo74UAiNR7uHJP6zGHUs7qQjA28XMWg7WVCJpP+BlH/7FK pBtCcw7TPd3bUFsbVHSpQPqelpRvV7J2hUTKbPDKza5pk86ZADmLoBRs4v8qnPhcSP//Lp 1YMygj/bOQpzopzlQcKKI3HqrYG9rxc= 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-533-XJftUXH_Nf2r6LqaUjWvUw-1; Thu, 25 Mar 2021 10:09:40 -0400 X-MC-Unique: XJftUXH_Nf2r6LqaUjWvUw-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 A367B190D341; Thu, 25 Mar 2021 14:09:38 +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 A799C5D736; Thu, 25 Mar 2021 14:09:36 +0000 (UTC) Subject: Re: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range To: Michal Hocko Cc: Oscar Salvador , Andrew Morton , Anshuman Khandual , Vlastimil Babka , Pavel Tatashin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3bc4168c-fd31-0c9a-44ac-88e25d524eef@redhat.com> <9591a0b8-c000-2f61-67a6-4402678fe50b@redhat.com> <31110e58-c99a-8dee-6f6e-98f456b77759@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <062bc5d7-a83c-1c1a-7b77-9f043643f4fa@redhat.com> Date: Thu, 25 Mar 2021 15:09:35 +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: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Stat-Signature: wkshmbe1jt4ipnuhre8feszp3h8s38p5 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 13F8AC0007D4 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf22; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616681389-41725 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 25.03.21 15:08, Michal Hocko wrote: > On Thu 25-03-21 13:40:45, David Hildenbrand wrote: >> On 25.03.21 13:35, Michal Hocko wrote: >>> On Thu 25-03-21 12:08:43, David Hildenbrand wrote: >>>> On 25.03.21 11:55, Oscar Salvador wrote: > [...] >>>>> - When moving the initialization/accounting to hot-add/hot-remove, >>>>> the section containing the vmemmap pages will remain offline. >>>>> It might get onlined once the pages get online in online_pages(), >>>>> or not if vmemmap pages span a whole section. >>>>> I remember (but maybe David rmemeber better) that that was a problem >>>>> wrt. pfn_to_online_page() and hybernation/kdump. >>>>> So, if that is really a problem, we would have to care of ot setting >>>>> the section to the right state. >>>> >>>> Good memory. Indeed, hibernation/kdump won't save the state of the vmemmap, >>>> because the memory is marked as offline and, thus, logically without any >>>> valuable content. >>> >>> Could you point me to the respective hibernation code please? I always >>> get lost in that area. Anyway, we do have the same problem even if the >>> whole accounting is handled during {on,off}lining, no? >> >> kernel/power/snapshot.c:saveable_page(). > > Thanks! So this is as I've suspected. The very same problem is present > if the memory block is marked offline. So we need a solution here > anyway. One way to go would be to consider these vmemmap pages always > online. pfn_to_online_page would have to special case them but we would > need to identify them first. I used to have PageVmemmap or something > like that in my early attempt to do this. > > That being said this is not an argument for one or the other aproach. > Both need fixing. Can you elaborate? What is the issue there? What needs fixing? -- Thanks, David / dhildenb