How to Prevent YUM from Updating the Kernel

http://www.howtogeek.com/50898/how-to-prevent-yum-from-updating-the-kernel/

Kernel update is the unique linux operation that needs rebooting the machine

To prevent accidentally updating kernel:

# yum –exclude=kernel* update

Or in /etc/yum.conf and /etc/dnf/dnf.conf

exclude=kernel*