1、install mainline

sudo add-apt-repository ppa:cappelikan/ppa
sudo apt update
sudo apt upgrade
sudo apt install mainline

2、query linux version list

sudo HTTP_PROXY=http://127.0.0.1:7890 HTTPS_PROXY=http://127.0.0.1:7890 mainline list

3、install new version

sudo HTTP_PROXY=http://127.0.0.1:7890 HTTPS_PROXY=http://127.0.0.1:7890 mainline install 6.18.6

4、check install or not

cat /proc/version 
Linux version 6.18.6-061806-generic (kernel@balboa) (x86_64-linux-gnu-gcc-15 (Ubuntu 15.2.0-4ubuntu4) 15.2.0, GNU ld (GNU Binutils for Ubuntu) 2.45) #202601171700 SMP PREEMPT_DYNAMIC Sat Jan 17 19:29:30 UTC 2026