kern/59963: Lock Order Reversal issue with PPP

["roy%marples.name@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         59963
>Category:       kern
>Synopsis:       Lock Order Reversal issue with PPP
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 05 11:00:00 +0000 2026
>Originator:     Roy Marples
>Release:        11.99.5
>Organization:
>Environment:
NetBSD cube 11.99.5 NetBSD 11.99.5 (GENERIC) #1: Sun Feb  1 19:02:06 GMT 2026  roy@cube:/home/roy/src/obj/sys/arch/amd64/compile/GENERIC amd64
>Description:
PPPoE traffic causes a missed heartbeat panic.
>How-To-Repeat:
Setup your NetBSD-11 host OS as a PPPoE server.
Setup your NetBSD-11 guest OS as a PPPoE client.

After starting the guest either the host or guest will panic with a hearbeat error.

As the host uses a USB keyboard it's challenging to get anything meaningful out of it.
The guest can be interrogated via VNC to get the following screenshot showing the stuck process.
https://mollari.netbsd.org/~roy/intr.png
>Fix: