Latest Git kernel: avahi-daemon[2410]: ioctl(): Inappropriate ioctl for device

[Jakub Kicinski]

On Sun, 2 Feb 2020 16:02:18 +0100, Christian Zigotzky wrote:
> On 02 February 2020 at 09:19 am, Christophe Leroy wrote:
> > Hello,
> >
> > Le 02/02/2020 à 01:08, Christian Zigotzky a écrit :  
> >> Hello,
> >>
> >> We regularly compile and test Linux kernels every day during the 
> >> merge window. Since Thuesday we have very high CPU loads because of 
> >> the avahi daemon on our desktop Linux systems (Ubuntu, Debian etc).
> >>
> >> Error message: avahi-daemon[2410]: ioctl(): Inappropriate ioctl for 
> >> device  
> >
> > Do you know which ioctl, on which device ?
> > Can you take a trace of running avahi-daemon with 'strace' ?
> >
> > Can you bisect ?
> >
> > Christophe  
> Hi Christophe,
> Hi All,
> 
> I figured out that the avahi-daemon has a problem with the IPv6 address 
> of a network interface since the Git kernel from Thursday. (Log attached)
> This generates high CPU usage because the avahi-daemon tries to access 
> the IPv6 address again and again and thereby it produces a lot of log 
> messages.
> 
> We figured out that the networking updates aren't responsible for this 
> issue because we created a test kernel on Wednesday. The issue is 
> somewhere in the commits from Wednesday night to Thursday (CET).

FWIW Thursday is when the latest networking pull came in, so could well
be networking related..

> Please compile the latest Git kernel and test it with a desktop linux 
> distribution for example Ubuntu. In my point of view there are many 
> desktop machines affected. Many server systems don't use the avahi 
> daemon so they aren't affected.
> 
> It's possible to deactivate the access to the IPv6 address with the 
> following line in the file "/etc/avahi/avahi-daemon.conf":
> 
> use-ipv6=no
> 
> After a reboot the CPU usage is normal again. This is only a temporary 
> solution.
> 
> Unfortunately I don't have the time for bisecting next week. I have a 
> lot of other work to do. In my point of view it is very important that 
> you also compile the latest Git kernels. Then you will see the issue and 
> then you have a better possibility to fix the issue.