You flip SELinux to permissive mode when things break, assuming you will catch the denial in your audit logs. But if you have heavy log rotation or a chatty system, the exact event you are hunting often gets flushed or buried under thousands of false positives. I have spent too many hours grep-ing through logs just to realize the audit daemon dropped the message because the buffer was full.

Why relying on the default log buffer is a mistake

The kernel audit backlog limit defaults to 64. On a busy production server, that fills up in milliseconds. When it hits the limit, the kernel starts dropping events. If your application crashes during that window, you get a clean audit log and a giant headache. You need to bump this early if you want reliable trace data.

auditctl -b 8192

• Bump the backlog buffer before you reproduce the failure
• Use ausearch -m AVC -ts recent to keep your focus narrow
• Check /var/log/audit/audit.log, not just dmesg, for the real culprit

Once you increase the buffer, keep an eye on auditctl -s. If you still see dropped events, your system noise is the problem, not the security policy. Clear out those excessive log rules before you spend another afternoon guessing why a service cannot bind to a port or read a socket.

Don’t just set it and forget it. If your app is truly broken, the fix is in the policy, not the permissive flag. Once you see the denial, write your module, load it, and get back to enforcing mode as fast as you can. Your future self will appreciate not having a gaping hole in your server’s security posture.