From: "Konrad ."len7hir@gmail.com

When we upgrade our kernels from 2.6.32.2 to 3.2.16 something strange has happened. On high traffic dovecot/auth looks like not responding.

We found a lot of this lines at the log:

[snip]

We compile Dovecot with poll instead of epoll (--with-ioloop=poll) and this works for us.

Is any problem with epoll on 3.2.x kernels?

Yes - and it's been discussed here.

Some "bright spark" rewrote the kernel epoll code to prevent DoS attacks caused by "excessive forking".

That "bright spark" clearly doesn't use imap or webserver software.

Redhat backported this change to kernels released after February 2012 and are about to release an emergency kernel release which removes it.

A number of $LARGE companies were "not happy"

As you've posted, compiling without epoll fixes the problem, but that doesn't help anyone using distro or repo packages.