max_allowed_packet reset

I am having some trouble with my global max_allowed_packet being reset. The variable is set in the my.cnf file but some process with the server, galera or xtrabackup periodically resets the value. I have not been able to determine from the logs where this is coming from. Anyone have a clue?

show me output of:
$ ps -ef | grep -v grep | grep mysql
$ cat /etc/my.cnf

Did you tried to diagnose it with general query log ? However, If this issue is rare then your general log will be huge and it incur disk IO.