From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 596F13FE4C for ; Tue, 14 Nov 2023 13:17:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="Jp+lSLB+" Received: from NAM11-BN8-obe.outbound.protection.outlook.com (mail-bn8nam11on2041.outbound.protection.outlook.com [40.107.236.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 417A1F1; Tue, 14 Nov 2023 05:17:05 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ZGFWxz0bh0t4IWwZxB+ld9cI7DygkGbfoeTXG4ZbnaSVbVDynY2hhP9Cya3l2K9TkLWMrQGPkU6cWRAhPVyXOBAI+Zkr/KfJPCmSiaRQvWyXU16GLF5df2Vu7+ARIQJfRX5bToT9d+wUbYiPnCXtDSCxPG5dcP46Xww8ud/sRb1EKHyhOxUOEmkSZjsRG7B88NO+Lq+8Jj604m0OryuGVA4i/7/yYLGh1h2hmhNqs1jiSvv+WnbLRu8YCisAcFXMc+Ud/Yv1voI0t1O7HQAwEiLh44CltjumMO8svooa/+pywYHrpsoDISa8djXa93oUy2/6QUTO+jIT6vXbmCI7OQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=UKySM8axderqUF36ppd/y9BLQ+m9RHxr8QQ+Iu3DPjg=; b=QJ14X6b64L01Zw/AoAhXD3CMgzpiyii4350cq5tJoLT9RIxUf9xBkTfZkn5GDNx9erV8z0GwjjdVxMxhDoJ2kxoZEFaZKngUWMyqxJXXjJ0lbxFqhrDfRwwtLjzPo/sFZL03reVsUo9qdqIlNpCtCqsMM0tD85eRxHfn978raLhY2uTmwVx6lc1Ayd4I9IjRGr1y+UlFmF9au3LsW7n9bYLTuKY9sKjLlte44bVE/xlNM4kfuVr/KI/jhDkGkS+5GaQ1QQ4gtAf4BXRgkEz/uJYOq37P5E/H/wSKohaY5E/yshFjVQJzTxt4UOD+NuTt4AS9tQ82CMnHwTl5fqExSA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=UKySM8axderqUF36ppd/y9BLQ+m9RHxr8QQ+Iu3DPjg=; b=Jp+lSLB+viRnwHUEhjUwY0DEgaUrRINR8IrjgVBw/rtjYfb5iTb7uUC85pwf6b0Kuv4fJBIvBzgoQ3Q/CFzF7v/AcxBxgjgpJE/c+lYLZRfQvjePWC/GP53b0uvDurdm+zjYfJZ/7M+0qP4Km+wQplj9ZzmUw1OlrzUSCkDLLEMmTA0QiNR0Kiwhw9UmOA6PqZmbH3wI0F7f1oqA38MF6AnOQnFmsGZz1R7Pa+gu2yU098H+D3hfwoiYYJvb8giCh6gBg5iBXdb5sJ/3yicvj1A9ChlenCRRFsHyq88KKzyKnHt9Db+Rz+TnIs0XLUfNNBxLz3CHJ0WFXJruHQr2vA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) by PH7PR12MB7332.namprd12.prod.outlook.com (2603:10b6:510:20f::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6977.31; Tue, 14 Nov 2023 13:16:59 +0000 Received: from LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::60d4:c1e3:e1aa:8f93]) by LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::60d4:c1e3:e1aa:8f93%4]) with mapi id 15.20.6977.029; Tue, 14 Nov 2023 13:16:59 +0000 Date: Tue, 14 Nov 2023 09:16:59 -0400 From: Jason Gunthorpe To: Mina Almasry Cc: Yunsheng Lin , Jakub Kicinski , davem@davemloft.net, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Willem de Bruijn , Kaiyuan Zhang , Jesper Dangaard Brouer , Ilias Apalodimas , Eric Dumazet , Christian =?utf-8?B?S8O2bmln?= , Matthew Wilcox , Linux-MM Subject: Re: [PATCH RFC 3/8] memory-provider: dmabuf devmem memory provider Message-ID: References: <20231113130041.58124-1-linyunsheng@huawei.com> <20231113130041.58124-4-linyunsheng@huawei.com> <20231113180554.1d1c6b1a@kernel.org> <0c39bd57-5d67-3255-9da2-3f3194ee5a66@huawei.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: MN2PR17CA0025.namprd17.prod.outlook.com (2603:10b6:208:15e::38) To LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV2PR12MB5869:EE_|PH7PR12MB7332:EE_ X-MS-Office365-Filtering-Correlation-Id: 681df35d-21cb-4515-29c4-08dbe513fbcc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LV2PR12MB5869.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(39860400002)(346002)(366004)(376002)(396003)(136003)(230922051799003)(186009)(1800799009)(64100799003)(451199024)(6486002)(478600001)(36756003)(6506007)(6916009)(316002)(54906003)(6512007)(66946007)(66556008)(66476007)(38100700002)(41300700001)(8676002)(4326008)(8936002)(5660300002)(86362001)(2616005)(7416002)(2906002)(26005);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?LMyTwaf15arbkFLhMC8Wq0aiG83PmhT1GNLksFTQDHKle3LlhuGfoGxAUFk5?= =?us-ascii?Q?ftexRSwWX+Gy5DI90LS6YiBB1zHeDSRC5R2R1wTwsiO/0qDQs0mQwQYr2shx?= =?us-ascii?Q?KCq16FCQZLq0FZ2AGzzr1MZTE1DFNukhubq0VrVxQ/OS/c/5Hu/AWJYvMOCG?= =?us-ascii?Q?OmGXQp7f+PhleQJyx/Sy8Q2rVtmsubxBX8/HrlS4GOb3FrAdsS/2DZSOSLy4?= =?us-ascii?Q?csIJ9qNKTSLwQBQUwIlcQ8Su+CKLP0JNkLb+RyDfiQglzx9s27EuHhCkbNXb?= =?us-ascii?Q?RI1FjWozhmRHF4uHN8E+P/OiJ0TqPUrX6qlbCRrWb3OfHbWf3G8WZa21Zp50?= =?us-ascii?Q?ZW0Jqbt8KvEaQqjdvmp70nbR/w2791rh/IPiy6u+N/kVbVobdper70hdSEC9?= =?us-ascii?Q?EdLhh0GmdOjOB8+knbi1Sqgiynme2R1h09eYibX3A/5duKrM/LwBPjpEUgeC?= =?us-ascii?Q?K02Otwa2rngMicqGBSt5wa27MiC+Xs37ZnMKCilQ34gNdIpR7JfIhjHH7LrI?= =?us-ascii?Q?GgYPBdQjSLIua1frzhB4oIeXnDJ6tCHsgOmzr5CHFIe45fNZoTW0IOwunMbI?= =?us-ascii?Q?kkkZFgo2pwB6wLzQTtxMDhopjLJqDVcC4g0XTn//M0yutXpNqH7n4X7suZUx?= =?us-ascii?Q?rTDwN6QfyeCSpTJMuQIOlqncrYYGnpV20nM6TvXHKsbBoWusoSVk5MYSEwQZ?= =?us-ascii?Q?KGojnEEI1de1/JIZ2I8VLkw/3RcYwbeeSNztOOtSU+B4mmucRmRmgJC9escF?= =?us-ascii?Q?/qF/U3HQRM8xMFu8E1J94ReZHCOSObP0ENks4iDzoeKAUXk2TLg4Ku+8BBrI?= =?us-ascii?Q?lWRoqSpl3aOOmcZvYsnhgYsoJVxQfq5A/uMfKEaVhF///ox01wfsMdPnEWr4?= =?us-ascii?Q?7J2EAcZMNTgCzPtz/9pJ62/hJQvDqo3vVJc+xgvrv2GnSgCa6SOolwOiXwiI?= =?us-ascii?Q?zlm+tEpWdA3dj1WJJ8waa7nhUC62RbOEwb4Y+WIuhBhQ42CAxIcpldmeQwE4?= =?us-ascii?Q?0GM8ca050SSdquBFdsFuOrIaH9OtJN3iM/6gQl2TcpU/vMICqr2sStavBH+z?= =?us-ascii?Q?DWlVRJ0exLX3rHtcvCX3mqUTvUbD9Z5Wu8dCkO1rlqlwUJOk2eNy2RRiRfM4?= =?us-ascii?Q?SHnXd1/7WSm/JPXdWTiXNeX2nkUOFAlhquiJBZf9nq5qBgzEv392fifm4ROf?= =?us-ascii?Q?y9bKco8MjxXK7HQDc1SPmzPT+eGVFuMc1IAsTYkpINHlvaI9cpKXbrO4TVIG?= =?us-ascii?Q?nxM9N9dj9WGnEimPdK4/5ENYc8SdyxCXF6WyRNBc/PS3oFWqymv+cek7Jv1X?= =?us-ascii?Q?Wfw6Qm0hQeYeRMCNW4eBhLNs+Gn7YuDSZ7mOkMbeA7V7wVhXDcjYA5sMzPjA?= =?us-ascii?Q?BQJi9fvg2OqhUBKQyBvWLzNgZ1zIWEJnX78eORGD2808t/sYdPJu08LyPfDg?= =?us-ascii?Q?72iYBzAPsY83B78S4tbcrrpNpfEpumFwWXIU1q+XITSVtmvQPL8Yp15GhZZm?= =?us-ascii?Q?TiduvGIHVGRx+SDzRdAXj9rX94MDbdwDDg6KdbcAyfGz71GeMEFMrwxW04Wk?= =?us-ascii?Q?wqq7G2BZETn3GE3SduM=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 681df35d-21cb-4515-29c4-08dbe513fbcc X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Nov 2023 13:16:59.5803 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: /qN8X/KasZ+/UrECFUunJt3TNALDiC+2J5oQm6t2kA7qRt+wAKc1FFrA/qB6ZMs8 X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7332 On Tue, Nov 14, 2023 at 04:21:26AM -0800, Mina Almasry wrote: > Actually because you put the 'strtuct page for devmem' in > skb->bv_frag, the net stack will grab the 'struct page' for devmem > using skb_frag_page() then call things like page_address(), kmap, > get_page, put_page, etc, etc, etc. Yikes, please no. If net has its own struct page look alike it has to stay entirely inside net. A non-mm owned struct page should not be passed into mm calls. It is just way too hacky to be seriously considered :( > > I would expect net stack, page pool, driver still see the 'struct page', > > only memory provider see the specific struct for itself, for the above, > > devmem memory provider sees the 'struct page_pool_iov'. > > > > The reason I still expect driver to see the 'struct page' is that driver > > will still need to support normal memory besides devmem. I wouldn't say this approach is unreasonable, but it does have to be done carefully to isolate the mm. Keeping the struct page in the API is going to make this very hard. Jason