A start job is running for docker application container engine.
After I switch to tty interface, it prompt the error that:
INFO: task systems-journal:348 blocked for more than 120 seconds. Tainted: P OE 4.15.0-43-generic #46-Ubuntu.
echo o> /proc/says/kernel/hung_task_timeout_secs disables this message.
It seems to be Nvidia-docker failed to install.