默认内核版本为3.10.0，现升级到4.18.9版本

查看当前内核版本

[root@localhost ~]# uname -r
3.10.0-514.el7.x86_64

自行查找需要的内核版本（比较全的lt和ml版本）：http://193.49.22.109/elrepo/kernel/el7/x86_64/RPMS/

或者下载网上找来的4.18.9版本内核文件(3个rpm包): 蓝奏网盘下载 kernel-4.18.9 密码:2u4l

[root@localhost ~]# tar xf kernel-ml-4.18.9.tar.gz
[root@localhost ~]# cd kernel-ml-4.18.9
[root@k8s-master kernel-ml-4.18.9]# yum localinstall kernel-ml*
Loaded plugins: fastestmirror
Examining kernel-ml-4.18.9-1.el7.elrepo.x86_64.rpm: kernel-ml-4.18.9-1.el7.elrepo.x86_64
Marking kernel-ml-4.18.9-1.el7.elrepo.x86_64.rpm to be installed
Examining kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64.rpm: kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64
Marking kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64.rpm to be installed
Examining linux-firmware-20180911-69.git85c5d90.el7.noarch.rpm: linux-firmware-20180911-69.git85c5d90.el7.noarch
linux-firmware-20180911-69.git85c5d90.el7.noarch.rpm: does not update installed package.
Resolving Dependencies
--> Running transaction check
---> Package kernel-ml.x86_64 0:4.18.9-1.el7.elrepo will be installed
---> Package kernel-ml-devel.x86_64 0:4.18.9-1.el7.elrepo will be installed
--> Finished Dependency Resolution

Dependencies Resolved

==========================================================================================================================================================================================================
 Package                                    Arch                              Version                                        Repository                                                              Size
==========================================================================================================================================================================================================
Installing:
 kernel-ml                                  x86_64                            4.18.9-1.el7.elrepo                            /kernel-ml-4.18.9-1.el7.elrepo.x86_64                                  203 M
 kernel-ml-devel                            x86_64                            4.18.9-1.el7.elrepo                            /kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64                             45 M

Transaction Summary
==========================================================================================================================================================================================================
Install  2 Packages

Total size: 248 M
Installed size: 248 M
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64                                                                                                                                             1/2 
  Installing : kernel-ml-4.18.9-1.el7.elrepo.x86_64                                                                                                                                                                                                                         2/2 
  Verifying  : kernel-ml-4.18.9-1.el7.elrepo.x86_64                                                                                                                                                                                                                         1/2 
  Verifying  : kernel-ml-devel-4.18.9-1.el7.elrepo.x86_64                                                                                                                                                                                                                   2/2 

Installed:
  kernel-ml.x86_64 0:4.18.9-1.el7.elrepo                                                                                              kernel-ml-devel.x86_64 0:4.18.9-1.el7.elrepo                                                                                             

Complete!

设置默认启动新内核 并重新生成grub2

# 查看当前内核
[root@k8s-master kernel-ml-4.18.9]# cat /boot/grub2/grub.cfg |grep ^menuentry
menuentry 'CentOS Linux (4.18.9-1.el7.elrepo.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1127.el7.x86_64-advanced-abb47b92-d268-4d8c-a9df-43bf44522cab' {
menuentry 'CentOS Linux (3.10.0-1127.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1127.el7.x86_64-advanced-abb47b92-d268-4d8c-a9df-43bf44522cab' {
menuentry 'CentOS Linux (0-rescue-63f20fbd07a048dc88574233e1ad966b) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-0-rescue-63f20fbd07a048dc88574233e1ad966b-advanced-abb47b92-d268-4d8c-a9df-43bf44522cab' {

# 设置启动内核
[root@localhost kernel-ml-4.18.9]# grub2-set-default 0
或者
[root@localhost kernel-ml-4.18.9]# grub2-set-default 'CentOS Linux (4.18.9-1.el7.elrepo.x86_64) 7 (Core)'

[root@localhost kernel-ml-4.18.9]# grub2-mkconfig -o /boot/grub2/grub.cfg

#重启系统
[root@localhost kernel-ml-4.18.9]# reboot

确认使用的内核版本

[root@localhost ~]# uname -r
4.18.9-1.el7.elrepo.x86_64