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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 73608C169C4 for ; Tue, 29 Jan 2019 20:58:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 34ACD20989 for ; Tue, 29 Jan 2019 20:58:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=Mellanox.com header.i=@Mellanox.com header.b="wPIJ6s3R" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729560AbfA2U6l (ORCPT ); Tue, 29 Jan 2019 15:58:41 -0500 Received: from mail-eopbgr10074.outbound.protection.outlook.com ([40.107.1.74]:2690 "EHLO EUR02-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726982AbfA2U6l (ORCPT ); Tue, 29 Jan 2019 15:58:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Mellanox.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=crFkFDL6HoTHuo/PPx9XXMrngUcivpMe02RcQCcP4Dw=; b=wPIJ6s3RufR9eRbueTSWeYwDR/GduiVw4YBfIt4Hyv9t8mxhipnmT5x+xctLElvR2StMFXmoL+54HR39tshJXNDeRAUC7vxl1XAhC3X1Cy+PX0q3j55ctAuvbG2JWYZaSrveE1JqsT7JaAkCLQX6COW0eFAJfxAcPDrDLKf+Uoc= Received: from DBBPR05MB6426.eurprd05.prod.outlook.com (20.179.42.80) by DBBPR05MB6316.eurprd05.prod.outlook.com (20.179.40.210) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1558.17; Tue, 29 Jan 2019 20:58:35 +0000 Received: from DBBPR05MB6426.eurprd05.prod.outlook.com ([fe80::24c2:321d:8b27:ae59]) by DBBPR05MB6426.eurprd05.prod.outlook.com ([fe80::24c2:321d:8b27:ae59%5]) with mapi id 15.20.1580.017; Tue, 29 Jan 2019 20:58:35 +0000 From: Jason Gunthorpe To: Logan Gunthorpe CC: Jerome Glisse , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Greg Kroah-Hartman , "Rafael J . Wysocki" , Bjorn Helgaas , Christian Koenig , Felix Kuehling , "linux-pci@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Joerg Roedel , "iommu@lists.linux-foundation.org" Subject: Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma Thread-Topic: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma Thread-Index: AQHUt/rA/dLikqWEmEaIytHIBNLPlqXGkyOAgAAJwICAAAX+AIAAEreAgAAFNYA= Date: Tue, 29 Jan 2019 20:58:35 +0000 Message-ID: <20190129205827.GM10108@mellanox.com> References: <20190129174728.6430-1-jglisse@redhat.com> <20190129174728.6430-4-jglisse@redhat.com> <20190129191120.GE3176@redhat.com> <20190129193250.GK10108@mellanox.com> <99c228c6-ef96-7594-cb43-78931966c75d@deltatee.com> In-Reply-To: <99c228c6-ef96-7594-cb43-78931966c75d@deltatee.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: MWHPR1201CA0011.namprd12.prod.outlook.com (2603:10b6:301:4a::21) To DBBPR05MB6426.eurprd05.prod.outlook.com (2603:10a6:10:c9::16) authentication-results: spf=none (sender IP is ) smtp.mailfrom=jgg@mellanox.com; x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [174.3.196.123] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DBBPR05MB6316;6:oqhIb0u9iptFxG72au529ZElgzV0PiVBxK/BUGjyuI0YWtygReVbXKYKW3hiA8m+IVK+0SFb6W1wgtkImociII9p7vPFvA/csJ+MIO+2AcIrat/Cv1ro7aVGBCZ9JLI/f2mAsxy+NXO0JoBMr14Zbruj/olZwdNnJisjxghVN70HHDVxkwGKi5K7Vewc/hjoUS7KVVRI/0KAgjBCid7JnnxZaGUeXEcH62BwGKSrxEun8dlMa71S7s49+67/AStBqrpovQ8q1R6AeAnll99kItv1NGVxXJ+Nz10xQ8l3tHSBQwYVq/pTPajSfBLUiWQmEXU1vWJb80z5zw8KX3TXFFOPn6aNK4tNSdmFayPKpvYmAQRh4wQXDU00yB7k9nC+kMgesjZlHPR4LAiWtHaM+C0FtLCA+I6ZYeXLF8am1C4Y9lcFxXKKhYArAldb6us/QY15wHfH0hm6D1vVNj+MAg==;5:+qE1CX8Kk+8ReQpRlS9HfuhUYonq7jwd+vRqR6f1izm8h/9WN78KeScFAqKM1e3ldeMIFVXcYweGEZXO3LFWwik5+lVIWQAtsWuwHdX++MD2anPBrMxpjK2HuVgK+OW/oqiMLALtb7/FiJvoOaOAQQukUaGoAAABeLpf88VA+DvwMxqivpdilw8+6+9rC9zYAhySs0YQLxCKhGSlF3ggGQ==;7:6S4/VJX86as4RyCmbY495fgr1tkTVPeh/uwmayYoKNFOtL63/sHtAdqur7XksCQmMIbNs6NWvAOYDeAqpi7WKKkshr2M97phnp69DfWJ4YM/yulf948+GzilfzgXrsl6ogQlZgfdMCNV6lvef56Ovg== x-ms-office365-filtering-correlation-id: f87fd651-db10-4ec2-3559-08d6862c8860 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600110)(711020)(4605077)(4618075)(2017052603328)(7153060)(7193020);SRVR:DBBPR05MB6316; x-ms-traffictypediagnostic: DBBPR05MB6316: x-microsoft-antispam-prvs: x-forefront-prvs: 093290AD39 x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(396003)(136003)(39860400002)(346002)(366004)(376002)(189003)(199004)(446003)(11346002)(54906003)(26005)(217873002)(6512007)(2616005)(476003)(66066001)(229853002)(186003)(4744005)(486006)(14454004)(8936002)(386003)(6506007)(36756003)(102836004)(93886005)(6116002)(256004)(3846002)(316002)(8676002)(81166006)(81156014)(478600001)(6916009)(71190400001)(71200400001)(7736002)(305945005)(4326008)(86362001)(76176011)(2906002)(97736004)(99286004)(52116002)(6436002)(6486002)(53936002)(6246003)(1076003)(33656002)(105586002)(25786009)(106356001)(7416002)(68736007);DIR:OUT;SFP:1101;SCL:1;SRVR:DBBPR05MB6316;H:DBBPR05MB6426.eurprd05.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: IP3i1PaWZXDdSoMl6tt0T0n/TmKuOYDAq7AG5E/7PwNXD7FQSSlN6BI+tdiFth23Ut+YfpcTJq4lnjUNN8O0OAqokO0wqL6QVMbrHCbj4VLUmY56jFi0UXrjgtzx3h88yzuwKOc6AOkb5qfmKADJvTaQWvyV8eSM9ujt8GRh2qBN+viGHs8Gk/5xXBX2VZCHJxNN8c3bg9BFr6Gzx5wwhgObARcALYbmAu6BXnYEODItf7aaTmxJi0Kz0+ejh9OueWOBcZIP3guQVJXV14K2mjtKk7IgJzUUI1eXdKN7rU1p0HwZAwz3rUMhaRlvRkKgz1AnBPGMjPFzHbheB6Hcv0i72sMMW9nJftY7jzvndr9mPBPgOjMXNgHGGXZ/tnUmLLY0BrzgESVZ6MBhzo/qAcprtqzp0+qN33lFGGe5RwI= Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: f87fd651-db10-4ec2-3559-08d6862c8860 X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Jan 2019 20:58:34.4173 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: DBBPR05MB6316 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 29, 2019 at 01:39:49PM -0700, Logan Gunthorpe wrote: > implement the mapping. And I don't think we should have 'special' vma's > for this (though we may need something to ensure we don't get mapping > requests mixed with different types of pages...). I think Jerome explained the point here is to have a 'special vma' rather than a 'special struct page' as, really, we don't need a struct page at all to make this work. If I recall your earlier attempts at adding struct page for BAR memory, it ran aground on issues related to O_DIRECT/sgls, etc, etc. This does seem to avoid that pitfall entirely as we can never accidently get into the SGL system with this kind of memory or VMA? Jason