drm/amdgpu: add OOM fallback on PRT teardown (v2)

Don't assume kmalloc will always succeed.

v2: agd: rebase

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 2510d25..1f1de21 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1194,14 +1194,22 @@ static void amdgpu_vm_update_prt_state(struct amdgpu_device *adev)
 }
 
 /**
+ * amdgpu_vm_prt_put - drop a PRT user
+ */
+static void amdgpu_vm_prt_put(struct amdgpu_device *adev)
+{
+       if (atomic_dec_return(&adev->vm_manager.num_prt_mappings) == 0)
+               amdgpu_vm_update_prt_state(adev);
+}
+
+/**
  * amdgpu_vm_prt - callback for updating the PRT status
  */
 static void amdgpu_vm_prt_cb(struct dma_fence *fence, struct dma_fence_cb *_cb)
 {
        struct amdgpu_prt_cb *cb = container_of(_cb, struct amdgpu_prt_cb, cb);
 
-       if (atomic_dec_return(&cb->adev->vm_manager.num_prt_mappings) == 0)
-               amdgpu_vm_update_prt_state(cb->adev);
+       amdgpu_vm_prt_put(cb->adev);
        kfree(cb);
 }
 
@@ -1224,10 +1232,18 @@ static void amdgpu_vm_free_mapping(struct amdgpu_device *adev,
                struct amdgpu_prt_cb *cb = kmalloc(sizeof(struct amdgpu_prt_cb),
                                                   GFP_KERNEL);
 
-               cb->adev = adev;
-               if (!fence || dma_fence_add_callback(fence, &cb->cb,
-                                                    amdgpu_vm_prt_cb))
-                       amdgpu_vm_prt_cb(fence, &cb->cb);
+               if (!cb) {
+                       /* Last resort when we are OOM */
+                       if (fence)
+                               dma_fence_wait(fence, false);
+
+                       amdgpu_vm_prt_put(cb->adev);
+               } else {
+                       cb->adev = adev;
+                       if (!fence || dma_fence_add_callback(fence, &cb->cb,
+                                                            amdgpu_vm_prt_cb))
+                               amdgpu_vm_prt_cb(fence, &cb->cb);
+               }
        }
        kfree(mapping);
 }