https://blog.wongcw.com/2018/09/27/%e6%9b%b4%e6%96%b0centos7%e4%b8%8a%e7%9a%84%e5%86%85%e6%a0%b8%e7%89%88%e6%9c%ac-update-the-version-of-kernel-on-centos7/