[Dovecot] pop3-login: Fatal: io_loop_handle_add: epoll_ctl(1, 5):

[Brandon Davidson]

I seem to have run into the same issue on two of our 12 Dovecot servers
this morning:

Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: child 7529 (login)
returned error 89 (Fatal failure) 
Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: child 7532 (login)
returned error 89 (Fatal failure) 
Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: Temporary failure in
creating login processes, slowing down for now 
Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: Temporary failure in
creating login processes, slowing down for now 
Oct 15 03:41:51 oh-popmap5p dovecot: imap-login: Fatal:
io_loop_handle_add: epoll_ctl(1, 5): Operation not permitted 
Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: Created login processes
successfully, unstalling 
Oct 15 03:41:51 oh-popmap5p dovecot: pop3-login: Fatal:
io_loop_handle_add: epoll_ctl(1, 5): Operation not permitted 
Oct 15 03:41:51 oh-popmap5p dovecot: dovecot: Created login processes
successfully, unstalling 
Oct 15 03:41:52 oh-popmap5p dovecot: dovecot: child 7576 (login)
returned error 89 (Fatal failure) 
Oct 15 03:41:52 oh-popmap5p dovecot: dovecot: Temporary failure in
creating login processes, slowing down for now

All 12 of our servers are running Dovecot 1.2.6, and all of them were
upgraded from 1.2.4 and restarted at Oct 13 04:00 by a cron job that
updates packages from our internal Yum repo. Only two of the servers
encountered this issue.

We run two separate master processes on each host - one for IMAP, one
for POP3. The IMAP service runs with a significantly increased
login_max_processes_count, and continued to serve user requests. The
POP3 service hit the max login process limit and stopped accepting new
connections, which triggered our alerting system.

For what it's worth, I was able to kill -HUP the master processes on
both machines and things seemed to return to normal. I also took the
precaution of killing off the pop3 login processes to get new
connections accepted.

Timo, is there any more information I could gather about this issue?
We've got a fairly large pool of machines, and odds are it will crop up
again if we wait long enough.

Thanks,

-Brad