Mounting ZFS with error 5 failed, since r271963 callout convert

[Michael Schmiedgen]

>> In previous months I had already the same problem with ZFS if
>> nvidia driver was loaded via /boot/loader.conf. It triggered
>> the same error. So I loaded the driver on demand with kldload
>> after login and everything (X + stuff) worked fine.
>>
>> Very strange...
>>
>> Does anyone have a clue what is going on here?
>
> So not loading the nvidia driver during boot fixed it?  That seems odd indeed.
> Did you recompile the driver after updating?
>

The nvidia driver problem started long before r271963. If
I update my CURRENT, non base stuff will be deleted and
ports will be completly new installed. The nvidia problem
persisted some of these cycles before I gave up. I can
test if the problem still exists.

But now there is a similar problem with applying kern_cons.c
in r271963. I do not know whether these two are related.

Please let me know if you want to see some configuration
or logs or anything.

Thanks,
   Michael