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=-7.3 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 C4FDFC43460 for ; Fri, 9 Apr 2021 18:59:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6BC9D6115B for ; Fri, 9 Apr 2021 18:59:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234794AbhDIS7w (ORCPT ); Fri, 9 Apr 2021 14:59:52 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48455 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234759AbhDIS7u (ORCPT ); Fri, 9 Apr 2021 14:59:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617994776; 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=I6z5k9pvR2eM8TAQJhvmPMLc2M+kDJxe7m6egiFSE+Y=; b=ByYf9gtdNNj92bTPnUnt5jBeA96mLz/v0DKnPlDCNvBd9DAaQLyKosJJRsx3Xa7LRKfN7l 3nOyUcMRbq7C7jGXRcJDEqdzXhMz+3PVtvuyivRniBg/b5R9vqUXFDyEojx3YYPO3PDTJW lOBVPtg2CJX6V0vwPWzf3HxtFeHfx2I= 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-520-wr-qbaoQN4yd8r-ArWGbWg-1; Fri, 09 Apr 2021 14:59:33 -0400 X-MC-Unique: wr-qbaoQN4yd8r-ArWGbWg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E39BB1922962; Fri, 9 Apr 2021 18:59:31 +0000 (UTC) Received: from [10.36.115.11] (ovpn-115-11.ams2.redhat.com [10.36.115.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id D975660C0F; Fri, 9 Apr 2021 18:59:24 +0000 (UTC) Subject: Re: [PATCH 03/10] mm/migrate: update node demotion order during on hotplug events To: Oscar Salvador , Dave Hansen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, shy828301@gmail.com, weixugc@google.com, rientjes@google.com, ying.huang@intel.com, dan.j.williams@intel.com References: <20210401183216.443C4443@viggo.jf.intel.com> <20210401183221.977831DE@viggo.jf.intel.com> <20210409101400.GA32159@linux> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Fri, 9 Apr 2021 20:59:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210409101400.GA32159@linux> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.04.21 12:14, Oscar Salvador wrote: > On Thu, Apr 08, 2021 at 11:52:51AM +0200, Oscar Salvador wrote: >> I am not really into PMEM, and I ignore whether we need >> CONFIG_MEMORY_HOTPLUG in order to have such memory on the system. >> If so, the following can be partly ignored. > > Ok, I refreshed by memory with [1]. > From that, it seems that in order to use PMEM as RAM we need CONFIG_MEMORY_HOTPLUG. > But is that always the case? Can happen that in some scenario PMEM comes ready > to use and we do not need the hotplug trick? The only way to add more System RAM is via add_memory() and friends like add_memory_driver_managed(). These all require CONFIG_MEMORY_HOTPLUG. Memory ballooning is a different case, but there we're only adjusting the managed page counters. -- Thanks, David / dhildenb