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[209.132.180.67]) by mx.google.com with ESMTP id cb16si2843877plb.290.2019.02.06.12.40.58; Wed, 06 Feb 2019 12:41:13 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=cv74FdRv; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726676AbfBFUkB (ORCPT + 99 others); Wed, 6 Feb 2019 15:40:01 -0500 Received: from a9-92.smtp-out.amazonses.com ([54.240.9.92]:48860 "EHLO a9-92.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726022AbfBFUkA (ORCPT ); Wed, 6 Feb 2019 15:40:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549485599; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=KCnUJlwQKrPyUUqRPNg3t9cL/cv5MgY2z3DU/pPTaqc=; b=cv74FdRvic7TI9m6xRCUtxP6ud5qi2iADMgwmPf2CPD4JZONmsdNN8aMKlS1ZDCg EjPx8+q7zsXPmP0+GM10VSu1+xf6UzXHgRGO/SgI3g8i/TsHOsfuR/+wqLBIZ3s8iaJ BlbOoVWBBlE9J2mOS4mq4qPUHB8t0VUts7llH+W8= Date: Wed, 6 Feb 2019 20:39:59 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Matthew Wilcox cc: Doug Ledford , Jason Gunthorpe , Jan Kara , Ira Weiny , lsf-pc@lists.linux-foundation.org, linux-rdma@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, John Hubbard , Jerome Glisse , Dan Williams , Dave Chinner , Michal Hocko Subject: Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA In-Reply-To: <20190206202021.GQ21860@bombadil.infradead.org> Message-ID: <01000168c489e945-b34792be-adb9-44ce-b7a3-83d9232848c1-000000@email.amazonses.com> References: <20190205175059.GB21617@iweiny-DESK2.sc.intel.com> <20190206095000.GA12006@quack2.suse.cz> <20190206173114.GB12227@ziepe.ca> <20190206175233.GN21860@bombadil.infradead.org> <47820c4d696aee41225854071ec73373a273fd4a.camel@redhat.com> <01000168c43d594c-7979fcf8-b9c1-4bda-b29a-500efe001d66-000000@email.amazonses.com> <20190206194055.GP21860@bombadil.infradead.org> <20190206202021.GQ21860@bombadil.infradead.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.06-54.240.9.92 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 6 Feb 2019, Matthew Wilcox wrote: > It's straightforward to migrate text pages from one DIMM to another; > you remove the PTEs from the CPU's page tables, copy the data over and > pagefaults put the new PTEs in place. We don't have a way to do similar > things to an RDMA device, do we? We have MMU notifier callbacks that can tell the device to release the mappings. And an RDMA device may operate in ODP mode which is on demand paging. With that data may be migrated as usual.