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Thu, 28 May 2026 23:48:20 -0700 (PDT) From: Mikhail Gavrilov To: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Alex Deucher , =?UTF-8?q?Christian=20K=C3=B6nig?= , David Airlie , Simona Vetter , Pierre-Eric Pelloux-Prayer , Sumit Semwal , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Mikhail Gavrilov Subject: [PATCH v6 1/2] drm/amdgpu: convert amdgpu_vm_lock_by_pasid() to drm_exec Date: Fri, 29 May 2026 11:47:38 +0500 Message-ID: <20260529064740.25060-2-mikhail.v.gavrilov@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260529064740.25060-1-mikhail.v.gavrilov@gmail.com> References: <20260521150841.20625-1-mikhail.v.gavrilov@gmail.com> <20260529064740.25060-1-mikhail.v.gavrilov@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit amdgpu_vm_lock_by_pasid() looks up a VM by PASID and reserves its root PD with a bare amdgpu_bo_reserve(), returning the still-reserved root to the caller. A caller that then needs to reserve further BOs (for example the devcoredump IB dump) ends up nesting reservation_ww_class_mutex acquires without a ww_acquire_ctx, which lockdep flags as recursive locking. Convert the helper to take a drm_exec context and lock the root PD with drm_exec_lock_obj(). Callers now run it inside a drm_exec_until_all_locked() loop and can lock additional BOs in the same ww ticket, so there is no nested ww_mutex acquire. The drm_exec context holds its own reference on the locked root BO, so the helper no longer hands a root reference back to the caller: the root output parameter is dropped, and the transient reference taken across the PASID lookup is released before returning. The only existing caller, amdgpu_vm_handle_fault(), is updated accordingly. Its is_compute_context path, which previously dropped the root reservation around svm_range_restore_pages() and re-took it, now finalises the drm_exec context and re-initialises a fresh one; behaviour is otherwise unchanged. No functional change intended for the page-fault path. Reviewed-by: Christian König Signed-off-by: Mikhail Gavrilov --- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 91 ++++++++++++++++---------- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 2 +- 2 files changed, 58 insertions(+), 35 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c index fccd758b6699..b9d93b664daf 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c @@ -2950,47 +2950,56 @@ int amdgpu_vm_ioctl(struct drm_device *dev, void *data, struct drm_file *filp) } /** - * amdgpu_vm_lock_by_pasid - return an amdgpu_vm and its root bo from a pasid, if possible. + * amdgpu_vm_lock_by_pasid - look up a VM by PASID and lock its root PD * @adev: amdgpu device pointer - * @root: root BO of the VM * @pasid: PASID of the VM - * The caller needs to unreserve and unref the root bo on success. + * @exec: drm_exec context to lock the root PD in + * + * Must be called from within a drm_exec_until_all_locked() loop; the caller + * runs drm_exec_retry_on_contention() afterwards. The drm_exec context holds + * a reference on the root BO until it is finalised. + * + * Return: the VM on success, or NULL if the PASID has no VM, the VM is being + * torn down, or locking the root PD failed. */ struct amdgpu_vm *amdgpu_vm_lock_by_pasid(struct amdgpu_device *adev, - struct amdgpu_bo **root, u32 pasid) + u32 pasid, struct drm_exec *exec) { unsigned long irqflags; + struct amdgpu_bo *root; struct amdgpu_vm *vm; int r; xa_lock_irqsave(&adev->vm_manager.pasids, irqflags); vm = xa_load(&adev->vm_manager.pasids, pasid); - *root = vm ? amdgpu_bo_ref(vm->root.bo) : NULL; + root = vm ? amdgpu_bo_ref(vm->root.bo) : NULL; xa_unlock_irqrestore(&adev->vm_manager.pasids, irqflags); - if (!*root) + if (!root) return NULL; - r = amdgpu_bo_reserve(*root, true); - if (r) - goto error_unref; + r = drm_exec_lock_obj(exec, &root->tbo.base); + if (r) { + amdgpu_bo_unref(&root); + return NULL; + } /* Double check that the VM still exists */ xa_lock_irqsave(&adev->vm_manager.pasids, irqflags); vm = xa_load(&adev->vm_manager.pasids, pasid); - if (vm && vm->root.bo != *root) + if (vm && vm->root.bo != root) vm = NULL; xa_unlock_irqrestore(&adev->vm_manager.pasids, irqflags); - if (!vm) - goto error_unlock; + if (!vm) { + drm_exec_unlock_obj(exec, &root->tbo.base); + amdgpu_bo_unref(&root); + return NULL; + } - return vm; -error_unlock: - amdgpu_bo_unreserve(*root); + /* The drm_exec context holds its own reference on the root BO. */ + amdgpu_bo_unref(&root); -error_unref: - amdgpu_bo_unref(root); - return NULL; + return vm; } /** @@ -3012,33 +3021,49 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid, uint64_t ts, bool write_fault) { bool is_compute_context = false; - struct amdgpu_bo *root; + struct drm_exec exec; uint64_t value, flags; struct amdgpu_vm *vm; int r; - vm = amdgpu_vm_lock_by_pasid(adev, &root, pasid); - if (!vm) + drm_exec_init(&exec, 0, 1); + drm_exec_until_all_locked(&exec) { + vm = amdgpu_vm_lock_by_pasid(adev, pasid, &exec); + drm_exec_retry_on_contention(&exec); + if (!vm) + break; + } + if (!vm) { + drm_exec_fini(&exec); return false; + } is_compute_context = vm->is_compute_context; if (is_compute_context) { - /* Unreserve root since svm_range_restore_pages might try to reserve it. */ - /* TODO: rework svm_range_restore_pages so that this isn't necessary. */ - amdgpu_bo_unreserve(root); + /* Release the root PD lock since svm_range_restore_pages + * might try to take it. + * TODO: rework svm_range_restore_pages so that this isn't + * necessary. + */ + drm_exec_fini(&exec); if (!svm_range_restore_pages(adev, pasid, vmid, - node_id, addr >> PAGE_SHIFT, ts, write_fault)) { - amdgpu_bo_unref(&root); + node_id, addr >> PAGE_SHIFT, ts, write_fault)) return true; - } - amdgpu_bo_unref(&root); /* Re-acquire the VM lock, could be that the VM was freed in between. */ - vm = amdgpu_vm_lock_by_pasid(adev, &root, pasid); - if (!vm) + drm_exec_init(&exec, 0, 1); + drm_exec_until_all_locked(&exec) { + vm = amdgpu_vm_lock_by_pasid(adev, pasid, &exec); + drm_exec_retry_on_contention(&exec); + if (!vm) + break; + } + if (!vm) { + drm_exec_fini(&exec); return false; + } } addr /= AMDGPU_GPU_PAGE_SIZE; @@ -3062,7 +3087,7 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid, value = 0; } - r = dma_resv_reserve_fences(root->tbo.base.resv, 1); + r = dma_resv_reserve_fences(vm->root.bo->tbo.base.resv, 1); if (r) { pr_debug("failed %d to reserve fence slot\n", r); goto error_unlock; @@ -3076,12 +3101,10 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid, r = amdgpu_vm_update_pdes(adev, vm, true); error_unlock: - amdgpu_bo_unreserve(root); + drm_exec_fini(&exec); if (r < 0) dev_err(adev->dev, "Can't handle page fault (%d)\n", r); - amdgpu_bo_unref(&root); - return false; } diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h index d083d7aab75c..0c6e3e0368c7 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h @@ -593,7 +593,7 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid, bool write_fault); struct amdgpu_vm *amdgpu_vm_lock_by_pasid(struct amdgpu_device *adev, - struct amdgpu_bo **root, u32 pasid); + u32 pasid, struct drm_exec *exec); void amdgpu_vm_set_task_info(struct amdgpu_vm *vm); -- 2.54.0