drm/ttm: return -EBUSY if waiting for busy BO fails

Returning -EAGAIN prevents ttm_bo_mem_space from trying alternate
placements and can lead to live-locks in amdgpu_cs, retrying
indefinitely and never succeeding.

Fixes: d367bd2a ("drm/ttm: fix busy memory to fail other user v10")
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -827,7 +827,7 @@ static int ttm_mem_evict_wait_busy(struct ttm_buffer_object *busy_bo,
 	if (!r)
 		reservation_object_unlock(busy_bo->resv);
 
-	return r == -EDEADLK ? -EAGAIN : r;
+	return r == -EDEADLK ? -EBUSY : r;
 }
 
 static int ttm_mem_evict_first(struct ttm_bo_device *bdev,