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Shutemov" , Pavel Begunkov , Mika Penttila , Dave Chinner , Theodore Ts'o , Peter Xu Subject: Re: [PATCH v6 3/3] mm/gup: disallow FOLL_LONGTERM GUP-fast writing to file-backed mappings Message-ID: References: <7d56b424-ba79-4b21-b02c-c89705533852@lucifer.local> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BLAPR03CA0110.namprd03.prod.outlook.com (2603:10b6:208:32a::25) To LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV2PR12MB5869:EE_|PH0PR12MB7012:EE_ X-MS-Office365-Filtering-Correlation-Id: c1dccf04-bcc1-40b0-1f24-08db4b144266 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:(13230028)(4636009)(396003)(39860400002)(366004)(136003)(346002)(376002)(451199021)(5660300002)(2906002)(186003)(54906003)(7416002)(7406005)(8676002)(8936002)(66476007)(26005)(6512007)(6506007)(4744005)(478600001)(86362001)(6486002)(2616005)(38100700002)(36756003)(66556008)(6916009)(66946007)(316002)(41300700001)(4326008);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?mrj5DnBw1hwoUFfjXdvV/oeVoUY44Q8dLwJls//LAu+puWagrJj7mxRipwbn?= =?us-ascii?Q?nogXX2xVIoHmADPl7QnHMjXwtzHfx7FU2oFeWMGrZ5ZVwSdiDQQ5A9zFNdPC?= =?us-ascii?Q?jp0iq0aFK4eHEe6+vTUhN3bN4ktygw5/gaZGkkBsuu6WIemZs8GjSz6w8Q5i?= =?us-ascii?Q?tn7YAqGCWLSvtFYWI/qA4hoqlPeL4lWduPwQAWaVqfrFif0/UNrKLzNevm1Y?= =?us-ascii?Q?lH346iu+uRsRAhhByyNb3bTSRaxbyY0REi7OvOnIdcq/BYC46IiXeKxHyop6?= =?us-ascii?Q?Y+3KFBIu8CQ27tcYYopE/8IfLBx7eQVLlNHCB166MC2YaLR+jX82ckdl5vhp?= =?us-ascii?Q?ITDFqWF/nuTeMpLEgycR070AEHXSy8hO9Yi7XpNG7IUf1iijCbU0xbnDlc2Q?= =?us-ascii?Q?RHlLWT4oEyE8CNRVnv7jRypOEP+nhbD9mUh7HDzABOeQv/+4WN8sPBEAHzB1?= =?us-ascii?Q?+I3DYtExoVb6l+rH9NPnpMIKmou+CrfGc8VJB+sO2CaEohHits6ZCSSi9WDG?= =?us-ascii?Q?o0W4Iqi/8AjahuYZROHUvEQXMg2sO//Gi95o2EuMZZDzOWfncSTaySKJ07OR?= =?us-ascii?Q?Mg+KKDmA3FwiO3+3VABYTuCTMB/HYG567iA871TxndLsHmwceJ0bftIhFiUl?= =?us-ascii?Q?xTGEYXXqZFeh6bF4cxQU38YR/JnBXwTMDguW6r+afu3s5PIWMYYhdK+zGbaQ?= =?us-ascii?Q?XSKs0DvXFS3E5uthQ3z1T5o/ZQ5wwk/ZHwgcX8HZq7MDfGDg3jBJ6JYzBS7a?= =?us-ascii?Q?pp3N3yAF3RrIzrvcWVER/Eei6xNcu7JtWL9wtH8UYKGw8fTHWtXQyxTcDmbe?= =?us-ascii?Q?Kq5J3QaX5DqF1V+HvJYyo2fpr6l0yZMJzNtOi9F07qjYwGkv9knrtC+4fXsb?= =?us-ascii?Q?goz1CejdDOW3RLD6uy0NqlIszRk0O55kq+fZ5zEaz6G6TGZXxdTJlLV1x9lj?= =?us-ascii?Q?egl4fC60469aktzaST2RBwCCHT54mxPezEo3EKa1meBhsE5Ym2pVTolCUg8s?= =?us-ascii?Q?GdaBHN8MvN9w5aBOMQtT7zm2pOnAlkQ7/etHnJ5She2D7feH2n1dEgWbrfIG?= =?us-ascii?Q?3c34h4PxWpHxB/uJHWC1wd4HNBawXp4jK87wBo4dRlyCJ8Q3m2+KH41lchl+?= =?us-ascii?Q?osV+dgSHjpN/mrDbYtNVHjKmBdg7ie7l9eMC0xQd6htCn6bdIPgys3CmhlTP?= =?us-ascii?Q?mRs77N+oy+kgbeMooS5G6VTJv5atBM5QnQRNKoa30+3hkUMuMf84Y0xRcY1a?= =?us-ascii?Q?bWbY/UDqvtTDLjxhMPhNGa7fl8A1GSWrngx21w5Bk2/ZA5U4rC0xknVDcGrN?= =?us-ascii?Q?hea4AMazfzxWKmMMpKVkl0aEXBIoEXK1Z5cdvOmQXhhPZ7NRpxxSajPvaCCm?= =?us-ascii?Q?xAJziv4lCV1A49krBMbzvbf+h9G/Il5RT3T/QPY5XLBd5bmm2b1qCfgsgUgm?= =?us-ascii?Q?PUL/7Es+o3+LSjZYylOAO/LenLhoZRCS45YVrhiL+b5nA1s7NA45mqMgBlrk?= =?us-ascii?Q?kLUF1s3+imF4XuSyhmKSeXEVXNd1v70zk95y1hwUGVCFgAMk5z8EfhErrPZm?= =?us-ascii?Q?YA2KTzbafV9bgAAHe1eDv7YONBtI4nlUQ0cUMSzM?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: c1dccf04-bcc1-40b0-1f24-08db4b144266 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 May 2023 13:50:59.0557 (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: ueCrK4TS9J1krYwHAd++AdGaeE0+lgdNsuKSqeP7B2xHrt2Cfex2pM339KHYujmO X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7012 Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Tue, May 02, 2023 at 03:47:43PM +0200, David Hildenbrand wrote: > > Eventually we want to implement a mechanism where we can dynamically pin in response to RPCIT. > > Okay, so IIRC we'll fail starting the domain early, that's good. And if we > pin all guest memory (instead of small pieces dynamically), there is little > existing use for file-backed RAM in such zPCI configurations (because memory > cannot be reclaimed either way if it's all pinned), so likely there are no > real existing users. Right, this is VFIO, the physical HW can't tolerate not having pinned memory, so something somewhere is always pinning it. Which, again, makes it weird/wrong that this KVM code is pinning it again :\ Jason