kern/55665: reliably trigerable KASSERT with gdb -p

[martin%NetBSD.org@localhost]

>Number:         55665
>Category:       kern
>Synopsis:       reliably trigerable KASSERT with gdb -p
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 17 06:10:00 +0000 2020
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.72
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD unpluged.duskware.de 9.99.72 NetBSD 9.99.72 (UNPLUGED) #340: Wed Sep 16 13:35:07 CEST 2020 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/evbarm/compile/UNPLUGED evbarm
Architecture: earmv5
Machine: evbarm
>Description:

I tried to debug makemandb and gdb "run" would not work for me, so I tried
to attach to the makemandb process with -p and immediately hit the (in-)famous
assertion:

[ 165.1514604] panic: kernel diagnostic assertion "pgrp->pg_jobc > 0" failed: f$
[ 165.1514604] cpu0: Begin traceback...
[ 165.1514604] 0xd4cafc94: netbsd:db_panic+0x14
[ 165.1514604] 0xd4cafcac: netbsd:vpanic+0x11c
[ 165.1514604] 0xd4cafcc4: netbsd:kern_assert+0x3c
[ 165.1514604] 0xd4cafd0c: netbsd:fixjobc+0x1ac
[ 165.1514604] 0xd4cafdac: netbsd:exit1+0x1c4  
[ 165.1514604] 0xd4cafdd4: netbsd:sigexit+0x1c0
[ 165.1514604] 0xd4cafe84: netbsd:postsig+0x22c
[ 165.1514604] 0xd4cafec4: netbsd:lwp_userret+0x1d4
[ 165.1514604] 0xd4cafeec: netbsd:userret+0x228
[ 165.1514604] 0xd4caffac: netbsd:syscall+0x1e4


Robert, I know you are diagnosing this issue - can we comment out the KASSERT
while you are tracking it down?

>How-To-Repeat:

This may depend on my shell setup, but for me it is as simple as:

  makemandb -Q &; gdb -p $( pgrep makemandb )

>Fix:
n/a