Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755176AbcJZLJf (ORCPT ); Wed, 26 Oct 2016 07:09:35 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59638 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754867AbcJZLJa (ORCPT ); Wed, 26 Oct 2016 07:09:30 -0400 From: "Aneesh Kumar K.V" To: Jerome Glisse Cc: Anshuman Khandual , linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, js1304@gmail.com, vbabka@suse.cz, mgorman@suse.de, minchan@kernel.org, akpm@linux-foundation.org, bsingharora@gmail.com Subject: Re: [RFC 0/8] Define coherent device memory node In-Reply-To: <20161025151637.GA6072@gmail.com> References: <1477283517-2504-1-git-send-email-khandual@linux.vnet.ibm.com> <20161024170902.GA5521@gmail.com> <87a8dtawas.fsf@linux.vnet.ibm.com> <20161025151637.GA6072@gmail.com> Date: Wed, 26 Oct 2016 16:39:19 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16102611-0016-0000-0000-00000501EEF0 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00005981; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000188; SDB=6.00772968; UDB=6.00371087; IPR=6.00549796; BA=6.00004834; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013107; XFM=3.00000011; UTC=2016-10-26 11:09:27 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16102611-0017-0000-0000-000034191985 Message-Id: <87y41bcqow.fsf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-10-26_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1610260196 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1331 Lines: 32 Jerome Glisse writes: > On Tue, Oct 25, 2016 at 09:56:35AM +0530, Aneesh Kumar K.V wrote: >> Jerome Glisse writes: >> >> > On Mon, Oct 24, 2016 at 10:01:49AM +0530, Anshuman Khandual wrote: >> > >> I looked at the hmm-v13 w.r.t migration and I guess some form of device >> callback/acceleration during migration is something we should definitely >> have. I still haven't figured out how non addressable and coherent device >> memory can fit together there. I was waiting for the page cache >> migration support to be pushed to the repository before I start looking >> at this closely. >> > > The page cache migration does not touch the migrate code path. My issue with > page cache is writeback. The only difference with existing migrate code is > refcount check for ZONE_DEVICE page. Everything else is the same. What about the radix tree ? does file system migrate_page callback handle replacing normal page with ZONE_DEVICE page/exceptional entries ? > > For writeback i need to use a bounce page so basicly i am trying to hook myself > along the ISA bounce infrastructure for bio and i think it is the easiest path > to solve this in my case. > > In your case where block device can also access the device memory you don't > even need to use bounce page for writeback. > -aneesh