--- x/drivers/iommu/iommufd/selftest.c
+++ y/drivers/iommu/iommufd/selftest.c
@@ -393,7 +393,8 @@ err_put:
 
 static void mock_dev_destroy(struct mock_dev *mdev)
 {
-	iommu_group_remove_device(&mdev->dev);
+	if (mdev->dev.iommu->iommu_dev != &mock_iommu_device)
+		iommu_group_remove_device(&mdev->dev);
 	device_del(&mdev->dev);
 	kfree(mdev->dev.iommu);
 	mdev->dev.iommu = NULL;