dd: vm_fault: pager read error

[grarpamp]

> Eugene Grosbein <eugen at grosbein.net> wrote:
>> Was there a ticket and revision number to look into that?
>> Because this issue is still present in 11.1 and r324300.

> It was meant to be
> https://svnweb.freebsd.org/base?view=revision&sortby=date&revision=320566

Found the thread... seems the same "Device not configured" problem,
just triggered differently by different users...
https://lists.freebsd.org/pipermail/freebsd-stable/2017-June/thread.html

I think 320566 may have quashed the two pager messages bits
(I don't seem to get them anymore), but the "Device not configured"
issue people observed is still there.

> If you are sure running kernel after 320566

Both 11.1R (r321309) and r324300 (same as snapshot) are after that.

> you should fill a PR.

Assuming there's not already one.
Then one for this issue when cleaned up.
And probably another for the geom.debugflags footshooting semantics.

Also I need to capture that mount -uw panic but have to look up again
the sysctl to prevent instant reboot / leave it onscreen or to debugger.