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Tsirkin" , Nicolin Chen , Shameerali Kolothum Thodi , "Liu, Yi L" , Keqian Zhu Subject: Re: [PATCH RFC 04/12] kernel/user: Allow user::locked_vm to be usable for iommufd Message-ID: <20220324114605.GX11336@nvidia.com> References: <808a871b3918dc067031085de3e8af6b49c6ef89.camel@linux.ibm.com> <20220322145741.GH11336@nvidia.com> <20220322092923.5bc79861.alex.williamson@redhat.com> <20220322161521.GJ11336@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL0PR02CA0144.namprd02.prod.outlook.com (2603:10b6:208:35::49) To MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 286fd7d7-bcff-45de-4734-08da0d8be1a3 X-MS-TrafficTypeDiagnostic: BN8PR12MB3027:EE_ X-Microsoft-Antispam-PRVS: 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:MN2PR12MB4192.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(4636009)(366004)(316002)(4326008)(66946007)(66556008)(66476007)(8676002)(33656002)(38100700002)(6506007)(2616005)(6486002)(86362001)(186003)(1076003)(26005)(6512007)(54906003)(6916009)(508600001)(83380400001)(4744005)(5660300002)(8936002)(2906002)(7416002)(36756003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?cs6PHT7qBtqfPPQOwP4buEMYCrSNNHMW26vOXlWSlIiEsQSrhHvJ0vI1Hd78?= =?us-ascii?Q?pcvAU0HvfaWPxgLEs7YJYyQtBfjUXunHCa7yVXxPLkt1RQaZzO6iDw/Lc1v1?= =?us-ascii?Q?iv/bU1NDvQJg1mpVhM17DVkVwEuLVXifi4TxtfNuUmBc77zF0vMgrIwjnoPx?= =?us-ascii?Q?biS/S8bOCttGC1wCB+WWuwaOnZwCOC+XVeTntLeITl0eunafcoVsF7NePoRz?= =?us-ascii?Q?Te6GlrtiK6jsDvMdWK5toDU9V6YeYqiqfqdHCgQFc5J8Ce7FWcE45DqLhyfd?= =?us-ascii?Q?05njo55SUro0wETPUBw4tMwEHQjVoAPTbrWaewjBoDkvNraVYz4hicpK+o5e?= =?us-ascii?Q?Hmkqniwe5983tdzMGM5Hhe+yGx7hh8fERWFunadNCVOnzf2KChe3tfWwKUg7?= =?us-ascii?Q?zJTkrAM71/ogKk1WhckozOVh0s+GspMnrnARHtjrRIFrC25PantJhMzHWN8T?= =?us-ascii?Q?oVSfDaJnpzAF0HkwAGK0pP0Uxg66m7UJmfPlXV32VtJ/N7YlVp0xBBSA4a7u?= =?us-ascii?Q?kZvJg6SkCeEBHBARQG0GhBm79Etf1wpIuZxHNvgbXaMOYIue2fbXj4HENvai?= =?us-ascii?Q?Dt0pg4oMulYzEGqpQWLGrIMA06PI287EpyCgBeF8BDL7xUYu2R68e0zXLrUn?= =?us-ascii?Q?tyN5PiLTeQz64t0wDH1uKMW2c7bemSpaN0jq757HOiJAp5khIgRbr6CDQDcm?= =?us-ascii?Q?/pTzNxGpSlOkm0XJt1eTEJXPy38sB/G6xbmVcLl0WPujyQzJ4W1OdLzBsy3j?= =?us-ascii?Q?+zxYlVBiyCMf9kxsuzL6Hi8eG5ic4XuvuIg3CXG/jyelFbgqRh/2oKRDdyrs?= =?us-ascii?Q?jFWFAyvY9qiETnherQmn3g+CW+uL9cM0RG9zmVYiQko6wbgwqLTnlvcNuhH/?= =?us-ascii?Q?/vnq4vf6CWSiKJDbNJQmVz/UpRp9dUfmsbaxShO8kx7qib8FKjP/0Bwgw4rT?= =?us-ascii?Q?53B03S59C8D81WfkvUJoAH4EGCy6qJcvfxeFwIx/2rKMy0ZZhmgULg1saeui?= =?us-ascii?Q?pQVH1l4uVlXBb/dpvDiZmFr/Yz1FA67wZhabhOgehSyWKRVw9zP7WFSNTZJP?= =?us-ascii?Q?LYtAw7u4OcybntkHCl8GSfudikNEtsHtpUSecXwbP0BdzMO5W6iwxv2DSiLO?= =?us-ascii?Q?+ayVAHLpA9HzLYBU3EOwfKgZAM3nDmNrfoyrMF15rL2lxP8n5yvzskQMQtOh?= =?us-ascii?Q?JqrZS20gKVu4I6mq+6bW7SykfxA5eYuycDfKrbZclavzKMXlBLPgPD4IRyDu?= =?us-ascii?Q?6DXC/OCBtZmJyKWC8oulRAlWcdWkdQV5t5suN7jeGoI07LXV5jg57rGctwWU?= =?us-ascii?Q?eqXUtUnwt5o8voGCzlGJ+HRriApNc6JnEog7NE0LclTwiC4qUApCtuyOB/EF?= =?us-ascii?Q?Vl89FKv7c/TiKc38NMhNz2K7EooSHQHh6cP3dSary1L0PPJCRQE1aSV/uSAW?= =?us-ascii?Q?HSV+nF+fGkOtZ2AaSL1Pv0gQ+gNmiN9+BzWaFtZVq1Go+vpMhaObMsFD48TC?= =?us-ascii?Q?irHVGJm0K0yFaJ3/wBkHf4nNey74mLlneeNraaE8N356f7osqW5h42T82IF0?= =?us-ascii?Q?GBdbUXyYHe7VgZ60oyKA6v2en486dCLgO4xR2XZLe9M2v+4ID7DY5fVZX8Yj?= =?us-ascii?Q?Lx+uIe/6D4qn3DZUvFn+fycUbWdxF2jlMAzwkkpM+fjQsXI5iURcWBT7+cfO?= =?us-ascii?Q?pLKH6/MOI+rlHY9K2qUBNp1NdUQs/CjQkuL5NCOrTdaL2Pk3OeiAUhktgpOH?= =?us-ascii?Q?rPx12HdrsQ=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 286fd7d7-bcff-45de-4734-08da0d8be1a3 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Mar 2022 11:46:06.8847 (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: X4fNg0yOuxpyztNcvdGXqigg4P8vZ919T53L8EkbfM/PPqoaes5H8kFjyPmmO2Aa X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR12MB3027 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Mar 24, 2022 at 11:50:47AM +0800, Jason Wang wrote: > It's simply because we don't want to break existing userspace. [1] I'm still waiting to hear what exactly breaks in real systems. As I explained this is not a significant change, but it could break something in a few special scenarios. Also the one place we do have ABI breaks is security, and ulimit is a security mechanism that isn't working right. So we do clearly need to understand *exactly* what real thing breaks - if anything. Jason