From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934195AbdDGO57 (ORCPT ); Fri, 7 Apr 2017 10:57:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47128 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933874AbdDGO5w (ORCPT ); Fri, 7 Apr 2017 10:57:52 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 50A732EF176 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jglisse@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 50A732EF176 Date: Fri, 7 Apr 2017 10:57:43 -0400 From: Jerome Glisse To: Michal Hocko Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, John Hubbard , Dan Williams , Naoya Horiguchi , David Nellans , Russell King , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , Rich Felker , Chris Metcalf , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: Re: [HMM 01/16] mm/memory/hotplug: add memory type parameter to arch_add/remove_memory Message-ID: <20170407145740.GA15335@redhat.com> References: <20170405204026.3940-1-jglisse@redhat.com> <20170405204026.3940-2-jglisse@redhat.com> <20170407121349.GB16392@dhcp22.suse.cz> <20170407143246.GA15098@redhat.com> <20170407144504.GG16413@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170407144504.GG16413@dhcp22.suse.cz> User-Agent: Mutt/1.8.0 (2017-02-23) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 07 Apr 2017 14:57:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 07, 2017 at 04:45:04PM +0200, Michal Hocko wrote: > On Fri 07-04-17 10:32:49, Jerome Glisse wrote: > > On Fri, Apr 07, 2017 at 02:13:49PM +0200, Michal Hocko wrote: > > > On Wed 05-04-17 16:40:11, Jérôme Glisse wrote: > > > > When hotpluging memory we want more information on the type of memory. > > > > This is to extend ZONE_DEVICE to support new type of memory other than > > > > the persistent memory. Existing user of ZONE_DEVICE (persistent memory) > > > > will be left un-modified. > > > > > > My current hotplug rework [1] is touching this path as well. It is not > > > really clear from the chage why you are changing this and what are the > > > further expectations of MEMORY_DEVICE_PERSISTENT. Infact I have replaced > > > for_device with want__memblock [2]. I plan to repost shortly but I would > > > like to understand your modifications more to reduce potential conflicts > > > in the code. Why do you need to distinguish different types of memory > > > anyway. > > > > > > [1] http://lkml.kernel.org/r/20170330115454.32154-1-mhocko@kernel.org > > > [2] the current patchset is in git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git > > > branch attempts/rewrite-mem_hotplug-WIP > > > > This is needed for UNADDRESSABLE memory type introduced in patch 3 and > > the arch specific bits are in patch 4. Basicly for UNADDRESSABLE memory > > i do not want the arch code to create a linear mapping for the range > > being hotpluged. Adding memory_type in this patch allow to distinguish > > between different type of ZONE_DEVICE. > > Why don't you use __add_pages directly then? That's a possibility, i wanted to keep the arch code in the loop in case some arch wanted to do something specific. But it is unlikely to ever be use outside x86 and i don't think we will want to do anything more than skipping linear mapping. Note that however for CDM when doing it with ZONE_DEVICE (i am gonna post an RFC for that) maybe the powerpc folks will want to know the memory type ie what kind of ZONE_DEVICE this is. I don't think they need it but i am not sure if there is anything specific needed for their next gen power 9 in respect of device memory. Andrew if Michal think it is better to not use arch_add_memory directly for my case than i can respin HMM patchset. Let me know. (Patch 1 and 4 would be drop, patch 3 and 14 would need updates from top of my head). Cheers, Jérôme