The default audit backlog size is 320. Backlog limit exceeded’ messages in /var/log/messages.

Please follow the below steps now:

1) Reboot the server if you find them in hung state
2) Login to the server and take a backup of /etc/audit/rules.d/audit.rules
3) Increase the value using the command: auditctl –b 1280  ( max value is 8192)
4) Edit file /etc/audit/rules.d/audit.rules & replace the value 320 with 1280
5) Restart the audit service using command: service auditd restart