升级内核
1.
$ rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
$ yum install -y https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
$ yum list available --disablerepo=* --enablerepo=elrepo-kernel
$ yum install -y kernel-lt-4.4.218-1.el7.elrepo --enablerepo=elrepo-kernel
$ cat /boot/grub2/grub.cfg | grep menuentry
grub2-set-default "CentOS Linux (4.4.218-1.el7.elrepo.x86_64) 7 (Core)"
$ grub2-editenv list
$ reboot