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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 A0E77C46470 for ; Wed, 8 Aug 2018 08:08:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 503B3216FB for ; Wed, 8 Aug 2018 08:08:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 503B3216FB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727314AbeHHK1S (ORCPT ); Wed, 8 Aug 2018 06:27:18 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:37318 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727028AbeHHK1S (ORCPT ); Wed, 8 Aug 2018 06:27:18 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5C6F8402315B; Wed, 8 Aug 2018 08:08:44 +0000 (UTC) Received: from [10.36.117.71] (ovpn-117-71.ams2.redhat.com [10.36.117.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2CAF21C70A; Wed, 8 Aug 2018 08:08:42 +0000 (UTC) Subject: Re: [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages To: Oscar Salvador Cc: Jerome Glisse , akpm@linux-foundation.org, mhocko@suse.com, dan.j.williams@intel.com, yasu.isimatu@gmail.com, logang@deltatee.com, dave.jiang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador References: <20180807133757.18352-1-osalvador@techadventures.net> <20180807133757.18352-3-osalvador@techadventures.net> <20180807135221.GA3301@redhat.com> <20180807204834.GA6844@techadventures.net> <20180807221345.GD3301@redhat.com> <20180808073835.GA9568@techadventures.net> <44f74b58-aae0-a44c-3b98-7b1aac186f8e@redhat.com> <20180808075614.GB9568@techadventures.net> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180808075614.GB9568@techadventures.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Wed, 08 Aug 2018 08:08:44 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Wed, 08 Aug 2018 08:08:44 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'david@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.08.2018 09:56, Oscar Salvador wrote: > On Wed, Aug 08, 2018 at 09:45:37AM +0200, David Hildenbrand wrote: >> On 08.08.2018 09:38, Oscar Salvador wrote: >>> On Tue, Aug 07, 2018 at 06:13:45PM -0400, Jerome Glisse wrote: >>>>> And since we know for sure that memhotplug-code cannot call it with ZONE_DEVICE, >>>>> I think this can be done easily. >>>> >>>> This might change down road but for now this is correct. They are >>>> talks to enumerate device memory through standard platform mechanisms >>>> and thus the kernel might see new types of resources down the road and >>>> maybe we will want to hotplug them directly from regular hotplug path >>>> as ZONE_DEVICE (lot of hypothetical at this point ;)). >>> >>> Well, I think that if that happens this whole thing will become >>> much easier, since we will not have several paths for doing the same thing. >>> >>> Another thing that I realized is that while we want to move all operation-pages >>> from remove_memory() path to offline_pages(), this can get tricky. >>> >>> Unless I am missing something, the devices from HMM and devm are not being registered >>> against "memory_subsys" struct, and so, they never get to call memory_subsys_offline() >>> and so offline_pages(). >>> >>> Which means that we would have to call __remove_zone() from those paths. >>> But this alone will not work. >> >> I mean, they move it to the zone ("replacing online/offlining code"), so >> they should take of removing it again. > > Yeah, I guess so. > > I mean, of course we can make this work by placing __remove_zone in devm_memremap_pages_release > and hmm_devmem_release functions and make sure to call offline_mem_sections first. > But sounds a bit "hacky".. > > Thanks > Then it is maybe time to cleary distinguish both types of memory, as they are fundamentally different when it comes to online/offline behavior. Ordinary ram: add_memory ... online_pages ... offline_pages remove_memory Device memory add_device_memory ... remove_device_memory So adding/removing from the zone and stuff can be handled there. -- Thanks, David / dhildenb