From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 5792E6B000A for ; Thu, 4 Oct 2018 02:28:18 -0400 (EDT) Received: by mail-pf1-f199.google.com with SMTP id i76-v6so5303406pfk.14 for ; Wed, 03 Oct 2018 23:28:18 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u37-v6si3355453pgl.585.2018.10.03.23.28.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Oct 2018 23:28:17 -0700 (PDT) Date: Thu, 4 Oct 2018 08:28:11 +0200 From: Michal Hocko Subject: Re: [PATCH RFC] mm/memory_hotplug: Introduce memory block types Message-ID: <20181004062811.GC22173@dhcp22.suse.cz> References: <20180928150357.12942-1-david@redhat.com> <20181001084038.GD18290@dhcp22.suse.cz> <20181002134734.GT18290@dhcp22.suse.cz> <98fb8d65-b641-2225-f842-8804c6f79a06@redhat.com> <20181003135407.GI4714@dhcp22.suse.cz> <9fef1f7d-2d7c-03f1-00e3-5fa657eda019@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9fef1f7d-2d7c-03f1-00e3-5fa657eda019@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: David Hildenbrand Cc: linux-mm@kvack.org, xen-devel@lists.xenproject.org, devel@linuxdriverproject.org, linux-acpi@vger.kernel.org, linux-sh@vger.kernel.org, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, Tony Luck , Fenghua Yu , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , Rich Felker , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "Rafael J. Wysocki" , Len Brown , Greg Kroah-Hartman , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Boris Ostrovsky , Juergen Gross , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , Mike Rapoport , Dan Williams , Stephen Rothwell , "Kirill A. Shutemov" , Nicholas Piggin , Jonathan =?iso-8859-1?Q?Neusch=E4fer?= , Joe Perches , Michael Neuling , Mauricio Faria de Oliveira , Balbir Singh , Rashmica Gupta , Pavel Tatashin , Rob Herring , Philippe Ombredanne , Kate Stewart , "mike.travis@hpe.com" , Joonsoo Kim , Oscar Salvador , Mathieu Malaterre On Wed 03-10-18 19:00:29, David Hildenbrand wrote: [...] > Let me rephrase: You state that user space has to make the decision and > that user should be able to set/reconfigure rules. That is perfectly fine. > > But then we should give user space access to sufficient information to > make a decision. This might be the type of memory as we learned (what > some part of this patch proposes), but maybe later more, e.g. to which > physical device memory belongs (e.g. to hotplug it all movable or all > normal) ... I am pretty sure that user knows he/she wants to use ballooning in HyperV or Xen, or that the memory hotplug should be used as a "RAS" feature to allow add and remove DIMMs for reliability. Why shouldn't we have a package to deploy an appropriate set of udev rules for each of those usecases? I am pretty sure you need some other plumbing to enable them anyway (e.g. RAS would require to have movable_node kernel parameters, ballooning a kernel module etc.). Really, one udev script to rule them all will simply never work. -- Michal Hocko SUSE Labs