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).

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.

Thanks,
Christian