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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] accel/ivpu: Use dma_resv_lock() instead of a custom mutex Content-Language: en-US To: Jacek Lawrynowicz , CC: , References: <20250528154325.500684-1-jacek.lawrynowicz@linux.intel.com> <26b8a17e-500d-d89d-de9f-c17108a6831d@amd.com> From: Lizhi Hou In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: None (SATLEXMB05.amd.com: lizhi.hou@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY1PEPF0001AE1A:EE_|MW4PR12MB6707:EE_ X-MS-Office365-Filtering-Correlation-Id: e87bbed1-e464-4e17-4ba9-08dda40f6d1a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|82310400026|376014|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?YTJCMzNkQU81UGRHNGgwby9BM0ZwVEZIZU1ZS01YM29Ec3ZJb2hXeHYwbXhW?= =?utf-8?B?cWJmWm1JRmNHaWhPVXpkYlFjSENUSmRheUZpTXNtblYzVkZSRzJvc1VPbUJ3?= =?utf-8?B?L2dWdythUG42TnhuYUpLZVFFRTk1VXBabGFrRkJudDU2RjJFK1EzUjhRcmpG?= =?utf-8?B?ZGJsWmpUWVF2NUZ5VGNCTUp2c1ZGdDlVYVd4MnE5VVhsWmVpTmR2MGZadEdX?= =?utf-8?B?clM5S0VZOVhRcDZySVRReHZjd0dNd1k1ei9sRTZ0M0RFUTRGQ0U1SWJwM1VJ?= =?utf-8?B?Slc3RERCc1d6WGhYaUMvV1Fwa1ZzZU1nWmFsNmtzeThkSDhWeXJqQ1V6azhD?= =?utf-8?B?cnNiNWxuemZra1RBcWxySlI5WjR3UXN3WHVPMmpyN2tER1dPb3k1N3BNYjlQ?= =?utf-8?B?QTZRN1JoVkpKenZUVFprSGJuKzIwc0RlSVgzOURRMC9GclhzOXAveHNmcm1J?= =?utf-8?B?OEJ2U0JWekpoVER6SFVCS04yN1VxODVndDc2THN5dmZ1bThJOW5LcTBHUXY3?= =?utf-8?B?a3ByVlREZXl1UE5uSjZiMVNubUxrdjlINHlDZTFYeHRtWU4wNlJ6Tm9SZjdI?= =?utf-8?B?ekZJSHdWM3hiSU4xOHdZbVFhZDFwUGNGcnBrM0hGZGNWeDQ0RWxKS1JTYm9j?= =?utf-8?B?V3ZEYVVoaWtqS3Y0c0tUYVgrblJBMjZ6UkplTm1kWVZRUkxIWTJoWk53UTFw?= =?utf-8?B?aUtIY2lIN1hkSHRVUTRHZHhSeDZ3ejlzOXlERm5LcVJXdEY0RnVDV1psWjdR?= =?utf-8?B?QmI2YSttWE5INXMzMmczN2Z1dEk2VUMyQnlNeUQvT0JxOHZROGFYQVpzU3Yy?= =?utf-8?B?UnBuYkFKOXZUMDg1aThtdG42WTgzSERnRlZMNGczM2tyL1FKT2x5ZDFXRFBW?= =?utf-8?B?L3pWeUQ3QnMxTVlMRVY2bTcvWUdnVFVkZWR5NG95R1YvazdBT2lsWDQwQTU4?= =?utf-8?B?bzBySmpuM2lEU2FXa2ZtOGMvaU4ySlRiK002TmJKbmp5QWxvckJRK3NpemtC?= =?utf-8?B?ZE9BNFpzOHduSmJ0YnB0WjFWbHdTeGtqaDVMNm1ZaGRVUnRZZlg5bjZROHN6?= =?utf-8?B?RFZFR2xCNHFOK0R4S2RTN0VzdHBDUHdVeGpjb2hGQitLSytnVUVwK2hEL2FJ?= =?utf-8?B?RGkxMVhRc3JLQjBQODRJZ0dyYUhHRWVrRzdzMVF5U0JvMjJQOHNnNElIbmVB?= =?utf-8?B?aDBseDNXcG5xRGdoQWpHR0ZGZDJ6TGpWdzVSUWNrOWxURXo0T3hFUlBIT2RE?= =?utf-8?B?d3lQaFBzaWozMlNtWUNRR1JWUkN2TWdZSm5pSnEzeU1aT1hnVjFGYVA1UkhE?= =?utf-8?B?TDlUNUVGaFVvT0tCbTdKZXRhOXlqMEZGbmlkRU1FcElibnBkUlEvVlg1a2R5?= =?utf-8?B?UmtXZ2lqdkdQUkl5ZTNaTVpOaGw4RWRiVXk4Y3o1VWNhM0l5ZWRLSG5ScWdh?= =?utf-8?B?MyswRGU0MmdERGZZTlhqS0dreUNXM0xQc2tXdVhEWjFuMzg5aW5qNFpHQzN6?= =?utf-8?B?ODNXZGVXbE84Sm9ISXVVa1RPZVQ4WHZvVVoxS0tmcVFCMnUyVURDZ0ZOcElj?= =?utf-8?B?a1l5WklUZ1VoL01qSUFPQTBxOE9NVkJKSUhnT1ZJMk5TTmdrclg2dTlnNG1I?= =?utf-8?B?d0ZNMXR5NXNDbHlHOCthUjNMQm1HaElZMUNGeHc5NzREQ3NEYkdhOHhnMUV1?= =?utf-8?B?QmVRNm9aNExuSnBub1pKWUc0SXV6N29iSUtmVVlPT04yUmZ4RzhPM2FwcXlO?= =?utf-8?B?WGU1OFZFVWJ6czRaWnJCemdWaGtGNTFpbzl5WXVjZFVndjdHaFRvU3E3Y2VT?= =?utf-8?B?RHhDbGVISTNsa2VtN3RjWUFocjRZMmZJVU5pVktiZC83UldhVFJDb2t6V283?= =?utf-8?B?RHZwSktZSmgzTUxTTmdTb3JvWmVpbjZRcC8zVFJ5M0NTYTBKWlFZNks3dHpu?= =?utf-8?B?TENLVklDUkdoRytEN3MxR1BTMWluMXhFNzhhTHpSbkFNaERqS2U5SEpSMkpt?= =?utf-8?B?L2pTVUt4Y3B4WHFIU3IwMHBwZ0VkVTlLTGdyM2tCYTJ4YVBiYmNTUDhzK1dB?= =?utf-8?Q?DFsZlr?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB03.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(36860700013)(82310400026)(376014)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jun 2025 09:00:31.7121 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e87bbed1-e464-4e17-4ba9-08dda40f6d1a 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=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BY1PEPF0001AE1A.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6707 On 6/2/25 05:58, Jacek Lawrynowicz wrote: > Hi, > > On 5/28/2025 7:50 PM, Lizhi Hou wrote: >> On 5/28/25 08:43, Jacek Lawrynowicz wrote: >>> This fixes a potential race conditions in: >>>   - ivpu_bo_unbind_locked() where we modified the shmem->sgt without >>>     holding the dma_resv_lock(). >>>   - ivpu_bo_print_info() where we read the shmem->pages without >>>     holding the dma_resv_lock(). >>> >>> Using dma_resv_lock() also protects against future syncronisation >>> issues that may arise when accessing drm_gem_shmem_object or >>> drm_gem_object members. >>> >>> Fixes: 42328003ecb6 ("accel/ivpu: Refactor BO creation functions") >>> Cc: # v6.9+ >>> Signed-off-by: Jacek Lawrynowicz >>> --- >>>   drivers/accel/ivpu/ivpu_gem.c | 63 +++++++++++++++++++---------------- >>>   drivers/accel/ivpu/ivpu_gem.h |  1 - >>>   2 files changed, 34 insertions(+), 30 deletions(-) >>> >>> diff --git a/drivers/accel/ivpu/ivpu_gem.c b/drivers/accel/ivpu/ivpu_gem.c >>> index c193a80241f5f..5908268ca45e9 100644 >>> --- a/drivers/accel/ivpu/ivpu_gem.c >>> +++ b/drivers/accel/ivpu/ivpu_gem.c >>> @@ -33,6 +33,16 @@ static inline void ivpu_dbg_bo(struct ivpu_device *vdev, struct ivpu_bo *bo, con >>>            (bool)bo->base.base.import_attach); >>>   } >>>   +static inline int ivpu_bo_lock(struct ivpu_bo *bo) >>> +{ >>> +    return dma_resv_lock(bo->base.base.resv, NULL); >>> +} >>> + >>> +static inline void ivpu_bo_unlock(struct ivpu_bo *bo) >>> +{ >>> +    dma_resv_unlock(bo->base.base.resv); >>> +} >>> + >>>   /* >>>    * ivpu_bo_pin() - pin the backing physical pages and map them to VPU. >>>    * >>> @@ -43,22 +53,22 @@ static inline void ivpu_dbg_bo(struct ivpu_device *vdev, struct ivpu_bo *bo, con >>>   int __must_check ivpu_bo_pin(struct ivpu_bo *bo) >>>   { >>>       struct ivpu_device *vdev = ivpu_bo_to_vdev(bo); >>> +    struct sg_table *sgt; >>>       int ret = 0; >>>   -    mutex_lock(&bo->lock); >>> - >>>       ivpu_dbg_bo(vdev, bo, "pin"); >>> -    drm_WARN_ON(&vdev->drm, !bo->ctx); >>>   -    if (!bo->mmu_mapped) { >>> -        struct sg_table *sgt = drm_gem_shmem_get_pages_sgt(&bo->base); >>> +    sgt = drm_gem_shmem_get_pages_sgt(&bo->base); >>> +    if (IS_ERR(sgt)) { >>> +        ret = PTR_ERR(sgt); >>> +        ivpu_err(vdev, "Failed to map BO in IOMMU: %d\n", ret); >>> +        return ret; >>> +    } >>>   -        if (IS_ERR(sgt)) { >>> -            ret = PTR_ERR(sgt); >>> -            ivpu_err(vdev, "Failed to map BO in IOMMU: %d\n", ret); >>> -            goto unlock; >>> -        } >>> +    ivpu_bo_lock(bo); >>>   +    if (!bo->mmu_mapped) { >>> +        drm_WARN_ON(&vdev->drm, !bo->ctx); >>>           ret = ivpu_mmu_context_map_sgt(vdev, bo->ctx, bo->vpu_addr, sgt, >>>                              ivpu_bo_is_snooped(bo)); >>>           if (ret) { >>> @@ -69,7 +79,7 @@ int __must_check ivpu_bo_pin(struct ivpu_bo *bo) >>>       } >>>     unlock: >>> -    mutex_unlock(&bo->lock); >>> +    ivpu_bo_unlock(bo); >>>         return ret; >>>   } >>> @@ -84,7 +94,7 @@ ivpu_bo_alloc_vpu_addr(struct ivpu_bo *bo, struct ivpu_mmu_context *ctx, >>>       if (!drm_dev_enter(&vdev->drm, &idx)) >>>           return -ENODEV; >>>   -    mutex_lock(&bo->lock); >>> +    ivpu_bo_lock(bo); >>>         ret = ivpu_mmu_context_insert_node(ctx, range, ivpu_bo_size(bo), &bo->mm_node); >>>       if (!ret) { >>> @@ -94,7 +104,7 @@ ivpu_bo_alloc_vpu_addr(struct ivpu_bo *bo, struct ivpu_mmu_context *ctx, >>>           ivpu_err(vdev, "Failed to add BO to context %u: %d\n", ctx->id, ret); >>>       } >>>   -    mutex_unlock(&bo->lock); >>> +    ivpu_bo_unlock(bo); >>>         drm_dev_exit(idx); >>>   @@ -105,7 +115,7 @@ static void ivpu_bo_unbind_locked(struct ivpu_bo *bo) >>>   { >>>       struct ivpu_device *vdev = ivpu_bo_to_vdev(bo); >>>   -    lockdep_assert(lockdep_is_held(&bo->lock) || !kref_read(&bo->base.base.refcount)); >>> +    lockdep_assert(dma_resv_held(bo->base.base.resv) || !kref_read(&bo->base.base.refcount)); >>>         if (bo->mmu_mapped) { >>>           drm_WARN_ON(&vdev->drm, !bo->ctx); >>> @@ -123,14 +133,12 @@ static void ivpu_bo_unbind_locked(struct ivpu_bo *bo) >>>       if (bo->base.base.import_attach) >>>           return; >>>   -    dma_resv_lock(bo->base.base.resv, NULL); >>>       if (bo->base.sgt) { >>>           dma_unmap_sgtable(vdev->drm.dev, bo->base.sgt, DMA_BIDIRECTIONAL, 0); >>>           sg_free_table(bo->base.sgt); >>>           kfree(bo->base.sgt); >>>           bo->base.sgt = NULL; >> Maybe not directly modify sgt but use drm_gem_shmem_purge()? > drm_gem_shmem_purge() also removes user mapping and backing pages. > In ivpu_bo_unbind_locked() we only want to unmap the buffer from the device as it being turned off. > We don't want to crash user process in this case and this will probably be the result of drm_gem_shmem_purge() na mmpapped buffer. > >> Will it potentially memleak without calling drm_gem_shmem_put_pages()? (if the bo is mmap, vmap etc) > There is no memory leak. We are calling drm_gem_shmem_get_pages_sgt() only once per object and drm_gem_shmem_free() frees all backing memory. Reviewed-by: Lizhi Hou > > Regards, > Jacek