if_tun failed to register

Hi :)

I just migrated a 4.8 server to -CURRENT and I have one question.
At boot time I get the following message:

------------------------------------------------
module_register: module if_tun already exists!
Module if_tun failed to register: 17
can't re-use a leaf (if_tun_debug)!
------------------------------------------------

Then I can see a "if_tun.ko" in my loaded modules.
What is this module ? I guess this has to do with the fact that I connect to
the
internet using ppp, but this module did not appear under 4.8.
Is there a kernel option I missed ?
I already have "device tun" in my kernel config file.

Thanks in advance.

-- 
Antoine Jacoutot 
ajacoutot_at_lphp.org 
http://www.lphp.org 
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