To restart FirewallD, use this command:
service firewalld restart
However, if FirewallD refuses to restart, and you check the status using this command:
service firewalld status
You might encounter this error:
firewalld.service: Found left-over process 1234567 (rmmod) in control group while starting unit. Ignoring.
top, you might see 100% CPU use and this:
3331497 root 20 0 6800 1568 1272 R 100.0 0.1 3:05.87 /sbin/rmmod nf_conntrack
This is an unresolved bug that happens at very rare times. Check if the installation is new, and if all software has been updated. Make sure there aren’t any other kernel reboot waiting to happen.
kill the process doesn’t work.
Be careful, because the command in question is trying to remove a firewall connection tracking module and if you forcibly remove it you network stack might become unstable.
To only remedy we’ve found for this ‘bug’ is to reboot. When rebooting, you might also encounter a new problem, namely a very long reboot. Upon investigation we found that the
rmmod process is stuck and a force shutdown was required. Typically this is not recommended. This is what you’ll see on the console if the process is stuck:
[4495235.473143 systemd-shutdown: Waiting for process: rmmod
Try to wait – force shutdowns are never a good idea.