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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?NJPGg9J+VCrVfZ6BjI06qQGLV7SDKFLUuM4sg/Be9A2MQefXDDFuSB10hEzL?= =?us-ascii?Q?HE/8ZMwRoXwYtZCFkF/tjKybyJpYcNrRsPgkmR6MUQMKKd4HaDs9mqPyEhHN?= =?us-ascii?Q?nwEie3f4la71QQVrmqYsr4oa/Y4G7BMhztKTXnfu+xqVRhuVA0Pucs9l7ptt?= =?us-ascii?Q?iVjx5z/bDNxrhAN9hLWtVxcMug9J+vZBJ9x/x6jnDe80wde3J4rNRwLZh+J3?= =?us-ascii?Q?v2UTTJ94ku+C2G5DZn7eT2E2eKygkByAv7vgQFgl4ECZiKuqcDqTtgIgfjEp?= =?us-ascii?Q?Piea/tBlF6n+W6A1DshtWcnTJqsD2QEKH3P1/TTyd5Rtfb/SDiASTsktAhRy?= =?us-ascii?Q?LUaTUX7nDHgqdpD5J2M8v7jB1QU7bwEHUvUW99elC4Ywl2BaQLyOtii/2bgG?= =?us-ascii?Q?Pm14otkfwYjL0CVLLf4SF/B6sJ6j82vPG4/d3peLDid+CN5QK0swS82YHj1+?= =?us-ascii?Q?RiPHMrXKbdcqMyp4unIjmY8v7wKqzUvR1qE3nNRSHCaMH1QzE6GTZuOCc42C?= =?us-ascii?Q?CrmEHY+TbvQDUMUGHjlmnFtfHRmsYsJTQ+U//R7OyaCazi9ZOgBZ67NsFtRs?= =?us-ascii?Q?rYMrWjaI0U4swMLj7C6D6IrJqDmmtvy+ugYckV5MyPgmkMfLMMJYXp4xtmpl?= =?us-ascii?Q?u+emVJUoAgZEqg14fEhC/2sHjHdtrk3ykqUfR8bHZLCeXksEesEKbBCGk5a/?= =?us-ascii?Q?oR1f4RejGO5TwNt7I5wvvmdf+jNrt30EuYBChjYtyWBhdRZGd/3jc3srhc2a?= =?us-ascii?Q?Vd83dkCrNDjbLqDN8DMbWuwKmLa15brkUp7o+Ap/9GbYupsSDkGQgWdN6lQ/?= =?us-ascii?Q?wTr918Hq3+0ecrLnow0uW9ZB6ycuu6B32yvG9krFzB4BV4MXdogdkhjp42Gl?= =?us-ascii?Q?FgGuOzIiuIv9CJRSYfQ383RawWsXhccNArkXcBAkAFXLbOAUhnOgB4XIy/ky?= =?us-ascii?Q?/KvUe3WQI0z2wAyk03+ENwhbpAOlYR9pZG4cL7JY5Syor9Gnexb1qYPb7eka?= =?us-ascii?Q?pyYP0mznWQg41C8IPoIO5a+I7tlCp45/A7M6UJVm3H9nWwLCSCxs5UBcGhBO?= =?us-ascii?Q?q3zW/VnckVlxX9dTeGEvTCQ6PJLk3/nvXPTemIrXQg9cdRcrXfgsFg0EEiu4?= =?us-ascii?Q?IsxktXoYgtFSik7P652777IPJCqdb3HIuDwveyKKre0caMpdH6zJnY8Zpe8Z?= =?us-ascii?Q?SnmnGqu5jpe5TTN4zzW729vPEHXTveESW269e6SsKR7yefs7aIYmEk6xWkF9?= =?us-ascii?Q?W00EacU2ZUVjqG63fJ3bWvxkQkXlFlo7bYLJDITrMqz9d21Z5fTEE8x14xKT?= =?us-ascii?Q?ZuWoJAZ2XOfivmhEY6ARmtc1?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6c9bc708-49b6-48e0-dceb-08d9932194cd X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Oct 2021 16:57:49.4865 (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: Aa5bQc0RK2gZ4zsJFOW3XDyNBclkONBzK5POKElOhL7t+5rbrl3TG97Z7QDgpM4r X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5352 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 19, 2021 at 09:57:34AM -0700, Jacob Pan wrote: > Hi Jason, > > On Fri, 15 Oct 2021 08:18:07 -0300, Jason Gunthorpe wrote: > > > On Fri, Oct 15, 2021 at 09:18:06AM +0000, Liu, Yi L wrote: > > > > > > Acquire from the xarray is > > > > rcu_lock() > > > > ioas = xa_load() > > > > if (ioas) > > > > if (down_read_trylock(&ioas->destroying_lock)) > > > > > > all good suggestions, will refine accordingly. Here destroying_lock is a > > > rw_semaphore. right? Since down_read_trylock() accepts a rwsem. > > > > Yes, you probably need a sleeping lock > > > I am not following why we want a sleeping lock inside RCU protected > section? trylock is not sleeping > For ioas, do we really care about the stale data to choose rw_lock vs RCU? > Destroying can be kfree_rcu? It needs a hard fence so things don't continue to use the IOS once it is destroyed. Jason