drm/amdgpu: Allow TTM to evict svm bo from same process

To support SVM range VRAM overcommitment, TTM should be able to evict
svm bo of same process to system memory, to get space to alloc new svm
bo.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c

@@ -159,11 +159,14 @@ static void amdkfd_fence_release(struct dma_fence *f)
 }
 
 /**
- * amdkfd_fence_check_mm - Check if @mm is same as that of the fence @f
- *  if same return TRUE else return FALSE.
+ * amdkfd_fence_check_mm - Check whether to prevent eviction of @f by @mm
  *
  * @f: [IN] fence
  * @mm: [IN] mm that needs to be verified
+ *
+ * Check if @mm is same as that of the fence @f, if same return TRUE else
+ * return FALSE.
+ * For svm bo, which support vram overcommitment, always return FALSE.
  */
 bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm)
 {
@@ -171,7 +174,7 @@ bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm)
 
 	if (!fence)
 		return false;
-	else if (fence->mm == mm)
+	else if (fence->mm == mm  && !fence->svm_bo)
 		return true;
 
 	return false;