ETOOMANYREFS related errors

[Timo Sirainen]

On 11 Mar 2016, at 03:48, Luis Ugalde <forondarena at gmail.com> wrote:
> 
> Hi,
> 
> I'm starting to see, on a pretty standard Debian Jessie installation, some
> error messages that are apparently related to the ETOOMANYREFS errno.
> 
> Firstly, the mail log shows this:
> dovecot: pop3-login: Error: fd_send(pop3, 18) failed: Too many references:
> cannot splice

Apparently because Linux thinks the same fd has been passed around recursively too many times: http://lkml.iu.edu/hypermail/linux/kernel/1101.0/01917.html

But Dovecot doesn't pass it recursively. It's only passed once from pop3-login to pop3 process.

> Is this something that Dovecot should be able to handle, or is it strictly
> Debian/libc/MySillyMistake related?
> 
> #uname -a
> Linux server 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3
> (2016-01-17) x86_64 GNU/Linux

I wonder if there's a new kernel change that started detecting the recursion wrong.