The SMEP is used to prevent the supervisor mode from executing user space code,
it is enabled by default since Linux kernel 3.0. But it could be disabled through
kernel boot parameters.
Ensure that Supervisor Mode Execution Prevention (SMEP) is not disabled by
the nosmep boot paramenter option.
Check that the line GRUB_CMDLINE_LINUX="..."
within /etc/default/grub
doesn't contain the argument nosmep.
Run the following command to update command line for already installed kernels:
# grubby --update-kernel=ALL --remove-args="nosmep"