Re: Panic / wedge from bridging tap and vlan

[John Klos <john%klos.com@localhost>]

> Can you get a stack trace out of this?
>
> gunzip -c </var/crash/netbsd.1.core.gz >/var/crash/netbsd.1.core
> echo bt | crash -M /var/crash/netbsd.1.core
>
> or maybe just see if dmesg shares the previous boot's output which
> might contain the panic and stack trace.

dmesg output didn't have anything, but crash gave:

Crash version 10.1_STABLE, image version nsfers
.
WARNING: versions differ, you may not be able to examine this image.
crash: _kvm_kvatop(0)
Kernel compiled without options LOCKDEBUG.
System panicked: lock error: Mutex: mutex_vector_enter,548: locking 
against myself: lock 0xffffd152aab57080 cpu 0 lwp 0xffffd152a9aeb480
Backtrace from time of crash is available.
sljit_modcmd() at 0
crash: _kvm_kvatop(ffffa508562b3ad8)
crash: kvm_read(0xffffa508562b3ad8, 8): invalid translation (invalid level 2 PDE)


> Obviously yes, this is a garden-variety unintended lock recursion
> probably in tap(4) whose locking is hokey, but we need the stack trace
> to track it down.
>
> Do you have steps to reproduce?

Because this is used for NAT for Internet, I can't test whenever I'd like. 
I'm still looking for a window.


> Can you take all of that information -- the panic message, the stack
> trace, the steps to reproduce -- and file a PR with it so it doesn't
> get lost and we can track pullups and close it when done?

Certainly. As soon as I can test again, I will.

Thanks!
John