Centos7 upgrade kernel

$ rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
$ rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
$ yum --enablerepo=elrepo-kernel install kernel-ml

$ vim /etc/default/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved #Change the saved here to 0
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet net.ifnames=0"
GRUB_DISABLE_RECOVERY="true"

$ grub2-mkconfig -o /boot/grub2/grub.cfg