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Mon, 30 Jun 2025 12:34:04 -0700 Date: Mon, 30 Jun 2025 12:34:03 -0700 From: Nicolin Chen To: Xu Yilun CC: , , , , , , , , , , , , , Subject: Re: [PATCH v3 2/5] iommufd: Destroy vdevice on idevice destroy Message-ID: References: <20250627033809.1730752-1-yilun.xu@linux.intel.com> <20250627033809.1730752-3-yilun.xu@linux.intel.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250627033809.1730752-3-yilun.xu@linux.intel.com> X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN1PEPF00036F42:EE_|BY1PR12MB8446:EE_ X-MS-Office365-Filtering-Correlation-Id: 7e2a20af-25af-453b-4c8f-08ddb80d1a7e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|36860700013|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?FLkPjQ9d0iR6qNwYiNLyBmhB988DVZxIUKUJ9XWDmtXdGHiCyU5NcegQu4fN?= =?us-ascii?Q?Af4WlbWCE7mzMvxEPIPl3b5PaG3aFnQcfUnXG0ZYZnWFCbt6PUWjozRIig6I?= =?us-ascii?Q?ImZktojA0lZB+iyF1CfU1G317tWuI1neSp21spnQpAzW6Vx2N9V46HO/TWxg?= =?us-ascii?Q?eUzJRbZpZKThGEd+tXFkzlLzieQol9xY5NBccw+FBIfdfkopgcFj+OOyVslF?= =?us-ascii?Q?xyOH1hviNcjxXE0I8g5SWmGar2aN2+P7UuZjZYTGa0xwtU533pkrjz+33kXq?= =?us-ascii?Q?nxMj/NcTO8vaxQoyyZcEMagiV3zVuiomPAU4S65iQxCuo4DsYu+pBe6O7ni6?= =?us-ascii?Q?BTADA4h3ANwcuQhmklvgZZ+x+gBJ+DSZI+VuS4SXvNuExoZoOfOh6V+OTR6V?= =?us-ascii?Q?qGrxkoD9d3EwFhwrUWz3V+pjxeQvMtrpugH6gR4XQbRhX3EnKgVunsh9C9fN?= =?us-ascii?Q?LEtKDLbaBaJ87rMafm5dKWwx+v33RKb67n4tETD8RMxUUwZjVzRczSWjy/yU?= =?us-ascii?Q?V4t3Ebvhl9v7h86WknwPtpzuvfCV9TBvZwXwxZtVRbvQnlqF1ZavP5mIRegD?= =?us-ascii?Q?emCKnOlhpnV77ToW3YCHI0/+CDfRSbQ3gxAEx2jIBlTfpjv3UESZZpjnypnp?= =?us-ascii?Q?zX6Pott3LVHq0a9SLNNUz3r81ZyoFLi1xjRIVDUOq9jPCH9G7eyCEQtxT1I8?= =?us-ascii?Q?jeXO/8aV3W8RRtHp9a2ouIe4LTmQrCEbU+xVQTSbRaPXzxzCyKYiqqcpPayZ?= =?us-ascii?Q?+K//LcjTY7JLxJ3m8SzxFD/8u4Y1J53XnEwd3YtfAxS+cBA7Sd+dxa+nKpVX?= =?us-ascii?Q?54BRd/qGoFCJ7DIm56Yih4IPX5WLcdCne0q0QNHBou6sEdJxkkqJP3rH3WWK?= =?us-ascii?Q?KGeEj8gqEfrMcZreAzAOG/5wjykWJZiD2zkbT9L1qT7PyAHXj5Cw9caYbqQY?= =?us-ascii?Q?Ua/0SIlGIQsSVSfAnVcScWIXVUAyARFXKV8IFMkRI32pAMPM/eOC/RJGhNvw?= =?us-ascii?Q?IaiV6gbSgVhIWAOs0r8KqAFb+A2adFfb/mU4Ho9lMIDjciXsMrGZdyT2YDfJ?= =?us-ascii?Q?9kCvurK6EPLzgBgRYb6WakqVkCOC08/pAO0rtjoraIfSfeIsqGB4YThggbBw?= =?us-ascii?Q?x6lNOAe58iffvtUGa80Gy8C63CXRm9a7rGWwQW9mcPxqHXv4lH6Wzg/j0l7L?= =?us-ascii?Q?KQt12g2s+p1cUk6XdlP9Q+xLCriZ6CMJhDdCTyYuFCWoU4Cwbn2gCWpMmliQ?= =?us-ascii?Q?BdBLk9ls7TRnV0RyVar4vdK4JLyiyzum3tZAScUgMwAz84ELuaRU8UfYhaHG?= =?us-ascii?Q?8RKBM2VSsN2OrLQx1bl/qJUgX4gW9KC1yyCCvnprmHK0pYmED1rt8LYgwJVu?= =?us-ascii?Q?/6jpfB/xJ/PIKu6QgTuf79or2LxEP3iRP5UsQmDHvHxHM3ymSh3Jdxbg1Qbi?= =?us-ascii?Q?Sc+khfYqy3n4oRmTH3auWdNe7geQwdzAUCkNI0d7jewMbuD90RpriBJRVl2V?= =?us-ascii?Q?RaEasr2srt2pvQIQYwaxnvph4AmOTbv9oqQapGYrSJfbAwIoyWzeeYXYUQ?= =?us-ascii?Q?=3D=3D?= X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(1800799024)(36860700013)(7416014)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jun 2025 19:34:17.3737 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7e2a20af-25af-453b-4c8f-08ddb80d1a7e X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF00036F42.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY1PR12MB8446 On Fri, Jun 27, 2025 at 11:38:06AM +0800, Xu Yilun wrote: > +static void iommufd_device_remove_vdev(struct iommufd_device *idev) > +{ > + struct iommufd_vdevice *vdev; > + > + mutex_lock(&idev->igroup->lock); > + /* vdev has been completely destroyed by userspace */ > + if (!idev->vdev) > + goto out_unlock; > + > + vdev = iommufd_get_vdevice(idev->ictx, idev->vdev->obj.id); > + if (IS_ERR(vdev)) { > + /* > + * vdev is removed from xarray by userspace, but is not > + * destroyed/freed. Since iommufd_vdevice_abort() is reentrant, > + * safe to destroy vdev here. > + */ > + iommufd_vdevice_abort(&idev->vdev->obj); > + goto out_unlock; This is the case #3, i.e. a racing vdev destory, in the commit log? I think it is worth clarifying that there is a concurrent destroy: /* * An ongoing vdev destroy ioctl has removed the vdev from the * object xarray but has not finished iommufd_vdevice_destroy() * yet, as it is holding the same mutex. Destroy the vdev here, * i.e. the iommufd_vdevice_destroy() will be a NOP once it is * unlocked. */ > @@ -147,10 +183,12 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd) > if (rc) > goto out_abort; > iommufd_object_finalize(ucmd->ictx, &vdev->obj); > - goto out_put_idev; > + goto out_unlock_igroup; > > out_abort: > iommufd_object_abort_and_destroy(ucmd->ictx, &vdev->obj); > +out_unlock_igroup: > + mutex_unlock(&idev->igroup->lock); Looks like we will have to partially revert the _ucmd allocator, in this function: https://lore.kernel.org/all/107b24a3b791091bb09c92ffb0081c56c413b26d.1749882255.git.nicolinc@nvidia.com/ Please try fixing the conflicts on top of Jason's for-next tree. Thanks Nicolin