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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH V1] iommu/sva: Fix crash in iommu_sva_unbind_device() Content-Language: en-US To: Yi Liu , , , CC: , , , References: <20260224183056.2628698-1-lizhi.hou@amd.com> <1c486a5a-7115-44fc-9705-18b292cb9d00@intel.com> <14caa56f-999a-ae00-2840-e97080b4f7af@amd.com> <967d515c-f098-48ff-97cb-2de34f17aa29@intel.com> From: Lizhi Hou In-Reply-To: <967d515c-f098-48ff-97cb-2de34f17aa29@intel.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: None (SATLEXMB03.amd.com: lizhi.hou@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF000099DB:EE_|DS7PR12MB8204:EE_ X-MS-Office365-Filtering-Correlation-Id: 537931c7-5566-4503-7866-08de795351a1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(376014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 729TSP3q6LM8PmDy7vqNC6luvFbw1nKZEuD6MRLLWTDs027ECV2VrUjvehLgBXDcCS2DH3aBp54Y5sq+hHaaLDWrjGk6sAwlQs4/rglEa2TMJcrEgP5+7mVKx7mEdcnl9WiBUTyPCsPXpSVLkrf7i9K5HcEHKHAEQO2DlbBk4xYGpeMxHlqpxg+UVYPDh5EFcnhEVs8fHUAKYvvPBIQ0P/en9kKoGiWhNdAaF0iW+S3ySmVdgOn6V9bvBpM26uMHGwpIPVPryWN0QJd81T1YYc+D24ltvpS6sR4aSpLc8eRUXSb/PVfbnp+dF2rsfm0pDUdSIVAgvlrHqKdPdUwqIweHofEANLfcuiWRZkljvQlXcbye2Ezjh3BLo3v6hnnXkYQEjwX0CfNhiWrpQEpr0oRkLpQ0pLII0Nf/JHucRnLHs5yYBW+Kf5JQoA4+LeLs X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Mar 2026 18:33:09.1256 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 537931c7-5566-4503-7866-08de795351a1 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF000099DB.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8204 On 2/28/26 04:14, Yi Liu wrote: > > On 2/26/26 06:09, Lizhi Hou wrote: >> >>>> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c >>>> index 07d64908a05f..523b8c65c86f 100644 >>>> --- a/drivers/iommu/iommu-sva.c >>>> +++ b/drivers/iommu/iommu-sva.c >>>> @@ -179,6 +179,7 @@ void iommu_sva_unbind_device(struct iommu_sva >>>> *handle) >>>>               return; >>>>       } >>>> >>>> +     mmgrab(domain->mm); >>>>       iommu_detach_device_pasid(domain, dev, iommu_mm->pasid); >>>>       if (--domain->users == 0) { >>>>               list_del(&domain->next); >>>> @@ -190,6 +191,7 @@ void iommu_sva_unbind_device(struct iommu_sva >>>> *handle) >>>>               if (list_empty(&iommu_sva_mms)) >>>>                       iommu_sva_present = false; >>>>       } >>>> +     mmdrop(domain->mm); >>>> >>>>       mutex_unlock(&iommu_sva_lock); >>>>       kfree(handle); >>> >>> will moving the below hunk in front of iommu_domain_free() simpler? >>> Only when (--domain->users == 0), shall the code check if sva_domains >>> is empty. right? >> >> I am not sure if this can be moved in front of iommu_domain_free(). Will >> iommu_domain_free() be possible to impact sva_domains? > > sva_domains is used to track domains associated with the same mm in the > generic layer. iommu_domain_free() calls vendor iommu driver's free() op > with domain type specific operations. I don't think it should impact the > sva_domains. > >> iommu_domain_free() calls domain->ops->free(). Could this call back free >> sva_domain? > > I think so. Check intel_mm_free_notifier() as an example. So if this is true, after calling iommu_domain_free(), the following check list_empty(&iommu_mm->sva_domains) could become to true because of domain free. If we move the check in front (before iommu_domain_free()), the check could be false. That seems leading incorrect iommu_sva_present Lizhi > > Regards, > Yi Liu >