How to solve nvme name floated after boot with 4.15.0 kernel

 Symptom:

Nvme devie name changed in every reboot. (Ubuntu 18.04, kernel 4.15.0-29)

Solution:

Ubuntu Bug#1792660

A. upgrade Ubuntu kernel to 4.17 or later. 

B. 

1. keep Ubuntu kernel at 4.15, but upgrade kernel to 4.15.0-34.

2. modify kernel parameter "nvme_core.nultipath=0' in /etc/default/grub

ex. GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nvme_core.nultipath=0"