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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Oleg Nesterov Subject: Re: [PATCH v2] mm/gup: disallow GUP writing to file-backed mappings by default Message-ID: References: <4f16b1fc-6bc5-4e41-8e94-151c336fcf69@lucifer.local> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4f16b1fc-6bc5-4e41-8e94-151c336fcf69@lucifer.local> X-ClientProxiedBy: BL1PR13CA0276.namprd13.prod.outlook.com (2603:10b6:208:2bc::11) To LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV2PR12MB5869:EE_|SJ2PR12MB8830:EE_ X-MS-Office365-Filtering-Correlation-Id: 1190a044-5fcd-4e73-e8ea-08db451a08c3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?0+iLPiU+p6HZmm6VsdXfrv7LMdu0xh2QmepaTZo/h/pqjzKBQJiW1UaweWSe?= =?us-ascii?Q?zTMu38JFoBPwNR9FsYu9mZmLI6b6JK/d/Cp09QP1wXjTycOzrG7QUR+FNK5Q?= =?us-ascii?Q?llY6cnHbuMTCDBrMoM1tjSBw3MKc4CUpus2ao06p4wJiY6Z+GpX7E4B0IPSJ?= =?us-ascii?Q?haM1xyp2DeBIkShg3t90lcm3w0+YKNnzqd4vTcFqDQmI5dYeaYpGnzNiGim/?= =?us-ascii?Q?9WxZWOwCQ1lLDbFF26jPUZdxMqjYTBty4wkSW/tvMrXVhJzp5v6rV1dF5qRq?= =?us-ascii?Q?6Ra8czDqF5uV6IOCzxehgkyH+xfihTllAD0K9iqEY1XBl4+Z7qcROiDfFma9?= =?us-ascii?Q?9kHqQv5Jvr6gwoOCVNsXw794F8eeCrZ71d5wc/l92gtBNAUgD5WMeH6VaDAT?= =?us-ascii?Q?yC3eGVG1LKwf6c/jQKkHNldqCIMdDUxF7Pi6k7k6LS+n217JwYr5PuunGdGN?= =?us-ascii?Q?FCAyJfPef+ypbZuzehHrzPjsvXFPUw60Kea5pZkCU21M1Tpd80FFg6YAy7hf?= =?us-ascii?Q?VG/vzHOzaPpsUuMZOxDg30Zb97Zes9bHWZNP+/rc3crxKZiZDYKksdbhmXCL?= =?us-ascii?Q?gzwjAJZl/hXd7QZkAXx4l2aQ59o9t2Ht5WsRb3yrCNzQvhFLVjoibkhEcncl?= =?us-ascii?Q?96EkLLDf5NukmL2QX8cqJmv5LaNwSjRy5jjY5dFeLUbvojJolqjRPQRUcPo5?= =?us-ascii?Q?gmKHGqwIfy/OEVgGb75SEUTf0erJmrMiSu30lfAd3k15/NYX5S7Twu/5vtNi?= =?us-ascii?Q?oKb/8Ox0kkmh7K9/6dW9Yq/7MHECugkYqL969M41YgoIVSU2Mbqv4k4hprrR?= =?us-ascii?Q?4QB2hrN12FYNhArTMEP25tqLqQM8Kamu73xEj9wbA435upwLe38NDX77sXzO?= =?us-ascii?Q?yj95a5+psv3KdcFGNZtsuHxyCJmxLU5i9vrO+ueY1F8dtdYGQWcgrv8+dGhH?= =?us-ascii?Q?df0JSYkFtQtdpC3KZ0rrw3cgXaf8HvY5fCh4gj2n8vFxYLdk0MhHLmP0s3P4?= =?us-ascii?Q?K6ifmFXEy44XV7u1mk6bde5WkDO+Yue96yBRs1fW3M62qDgiq1fJ7kt5M+5y?= =?us-ascii?Q?qYqQy/BuFaDRoxT8kEzUZnianqGaMPxpST8cjRJfU5KOcxdJH5iHDofQ+RJq?= =?us-ascii?Q?1bbPInzdTU4JO6U4v6iocLCxEPVXtCUI79nSAM8rJ/+v2MH7cpDlbeHNAp2s?= =?us-ascii?Q?5IYodo+N/Fi5rqgH52snhatgkaxgX0uZ1bOezxCmN547w81TF92ZgBCkvQ0w?= =?us-ascii?Q?oOoof9XHJmky4/Oek27CTwx0e4LCBTwNSmLW/I5mfNENrFblNUvPIXQaqrsl?= =?us-ascii?Q?LIi73OTFTf+nrjNMKYc5VkfaYjt0N6pydRXKa9/pWODisWn/vjNohF1XJ0Gc?= =?us-ascii?Q?NVFkNnm+amATy8hFC68ZmpUmWUfdibWfnODNOP5/wOjmQdNh4HKdNI6oWNFA?= =?us-ascii?Q?67E6K6eFQNKlTut3IZTfWbIpF0Dz1AVEyoW44ZNu6WGlEhjSXshosF0+ujKk?= =?us-ascii?Q?mEbSLhWFog8HKu5bHQyZSxLA4vuVg5kEWonbr3hojQzLi3S0kJFzHjQ968lx?= =?us-ascii?Q?F5Q/P+/3VoI4uBrHbZ4tMkDRBmxDp06UzN6w+lME?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1190a044-5fcd-4e73-e8ea-08db451a08c3 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Apr 2023 23:17:12.4128 (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: LpKkJWeouBGfXQ/N5o2HCtSp4cSf5p9d5p74uKWM7C5HS93HweFgDJYeLDkT2Nt6 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8830 Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Tue, Apr 25, 2023 at 12:03:34AM +0100, Lorenzo Stoakes wrote: > Except you dirty a page that is mapped elsewhere that thought everything > was cleaned and... not sure the PTLs really help you much? If we have a writable PTE then while the PTE's PTL is held it is impossible for a FS to make the page clean as any cleaning action has to also take the PTL to make the PTE non-present or non-writable. > If we want to be more adventerous the opt-in variant could default to on > for FOLL_LONGTERM too, but that discussion can be had over on that patch > series. I think you should at least do this too to explain why io_uring code is moving into common code.. Jason