Re: port-arm/57102: vcmbox0 thread using 100% CPU

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Sat, 10 Dec 2022 16:05:00 +0000 (UTC)
> From: cryintothebluesky%gmail.com@localhost
> 
> The issue occurred on Raspberry Pi 4, used as NFS server. Initiated
> a large copy from Linux NFS client to NetBSD NFS server. Some time
> later, vcmbox0 thread was consuming 100% CPU and the following
> message was logged before I rebooted the system

If you catch this again, it would be helpful if you could start
crash(8), run

crash> ps

to find the thread occupying the CPU, which will look something like
this:

10618>10618 7   1         0   ffffa06b1676e940                 sh

Note the `>' on the line marking it as a running thread, and the
thread name is not `idle/N'.  Most likely the thread name will be
vcmbox0 or something.  Copy & paste the horrible number like
ffffa06b1676e940 into bt/a:

crash> bt/a ffffa06b1676e940

Sharing the stack trace should help track down what it's up to.

The full output of ps and ps/w might also be helpful, so it wouldn't
hurt to include those too.