drm/amdgpu: shrink critical section in amdgpu_amdkfd_gpuvm_free_memory_of_gpu

	struct kfd_bo_va_list *entry, *tmp;

	struct bo_vm_reservation_context ctx;

	struct ttm_validate_buffer *bo_list_entry;

	unsigned int mapped_to_gpu_memory;

	int ret;

	mutex_lock(&mem->lock);

	mapped_to_gpu_memory = mem->mapped_to_gpu_memory;

	mutex_unlock(&mem->lock);

	/* lock is not needed after this, since mem is unused and will

	 * be freed anyway

	 */

	if (mem->mapped_to_gpu_memory > 0) {

	if (mapped_to_gpu_memory > 0) {

		pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",

				mem->va, bo_size);

		mutex_unlock(&mem->lock);

		return -EBUSY;

	}

	mutex_unlock(&mem->lock);

	/* lock is not needed after this, since mem is unused and will

	 * be freed anyway

	 */

	/* No more MMU notifiers */

	amdgpu_mn_unregister(mem->bo);