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[209.132.183.28]) by mx.google.com with ESMTPS id f4si5318054qtk.237.2019.02.06.12.54.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Feb 2019 12:54:06 -0800 (PST) Received-SPF: pass (google.com: domain of dledford@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dledford@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=dledford@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 06BED7AE99; Wed, 6 Feb 2019 20:54:06 +0000 (UTC) Received: from haswell-e.nc.xsintricity.com (ovpn-112-17.rdu2.redhat.com [10.10.112.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 993DC62481; Wed, 6 Feb 2019 20:54:03 +0000 (UTC) Message-ID: Subject: Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA From: Doug Ledford To: Matthew Wilcox Cc: Christopher Lameter , 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 Date: Wed, 06 Feb 2019 15:54:01 -0500 In-Reply-To: <20190206202021.GQ21860@bombadil.infradead.org> 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> Organization: Red Hat, Inc. Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-qMmM3LVuejBi/UYuzebx" User-Agent: Evolution 3.30.4 (3.30.4-1.fc29) Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 06 Feb 2019 20:54:06 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --=-qMmM3LVuejBi/UYuzebx Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2019-02-06 at 12:20 -0800, Matthew Wilcox wrote: > On Wed, Feb 06, 2019 at 03:16:02PM -0500, Doug Ledford wrote: > > On Wed, 2019-02-06 at 11:40 -0800, Matthew Wilcox wrote: > > > On Wed, Feb 06, 2019 at 07:16:21PM +0000, Christopher Lameter wrote: > > > > though? If we only allow this use case then we may not have to worr= y about > > > > long term GUP because DAX mapped files will stay in the physical lo= cation > > > > regardless. > > >=20 > > > ... except for truncate. And now that I think about it, there was a > > > desire to support hot-unplug which also needed revoke. > >=20 > > We already support hot unplug of RDMA devices. But it is extreme. How > > does hot unplug deal with a program running from the device (something > > that would have returned ETXTBSY)? >=20 > Not hot-unplugging the RDMA device but hot-unplugging an NV-DIMM. Is an NV-DIMM the only thing we use DAX on? --=20 Doug Ledford GPG KeyID: B826A3330E572FDD Key fingerprint =3D AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD --=-qMmM3LVuejBi/UYuzebx Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEErmsb2hIrI7QmWxJ0uCajMw5XL90FAlxbSWkACgkQuCajMw5X L91cWw/+KzistDQ9VmIIUgMW9sZm4sOOkRYqqgNNyQuR0DEr0E46tfR2Bb7tXSvu ZL0Ut9r4TsNA0P0d+2bjykL99zyiYUuDJLJOKbBt/JxcX7tNe8BFsw23hJgItUxQ Thd6/1PQ0Da/zgRx05Pfwd+DWnDcNPAxTgMRFoAHxMj1EWpGOwlLaX9RFz18am4A l1W6PDbX7qJNQDIr03F+T7H/tMv9dR5ENIoI2OyzyoANQcqbFQZty/+S5NAER9BI 4ljdIJ3vcTtxLworx6S42nH/cF9KnwOWNiO58uLWKzc3tf12IAQ6aQ+zkOZTgfca /y+gD0MKI6rAbw1sbrl+xIiDJeBwz+jaBAqRWbQbv5vEZdl4oHk1L2JgHRnuFFWr XO30wc72FUHJXkyjbhNFGsI2Xa/smeCZn/WCIGUY5iXYmcTUkS2TrIJg9Dpo/dd/ rFNP7CmFJ+Yga8Bp7LIhDuQTAb28AFBT/QUWb/vPHg8gBregYfUE8KVPjFDjD2YH DvBTf2VcderUcFMM5Ibjc/00rutEZbNvP917bLdY3geo1e/HqR9GEY8QteslRpOm tKTMdMJwSB/pnXza+J5NtcRiVpDY3qdyHOzrZJNd/6cihC8L8vUl8P31IgyfKNE+ zcCOLhdMK5C+GzThv2s0upxtJa8CkmZvEzt7WkvyMet6bnrbGbY= =Rb/V -----END PGP SIGNATURE----- --=-qMmM3LVuejBi/UYuzebx--