kern/58430: Panic in vdead_check()

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         58430
>Category:       kern
>Synopsis:       Panic in vdead_check()
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 15 16:50:00 +0000 2024
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date 2024-07-01 17:47:24 Z
>Organization:
>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

One of my NetBSD systems paniced and dumped a kernel core.
The backtrace shown by gdb is:

#0  0xc012ce85 in maybe_dump (howto=260) at /usr/src/sys/arch/i386/i386/machdep.c:725
#1  cpu_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /usr/src/sys/arch/i386/i386/machdep.c:746
#2  0xc0c62338 in kern_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /usr/src/sys/kern/kern_reboot.c:91
#3  0xc0ca74a9 in vpanic (fmt=fmt@entry=0xc11b1054 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ", ap=0xe080ce98 "\273\017\033\301uo(\301O++\301+\b") at /usr/src/sys/kern/subr_prf.c:288
#4  0xc0e6e21c in kern_assert (fmt=<optimized out>, fmt@entry=0xc11b1054 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ") at /usr/src/sys/lib/libkern/kern_assert.c:51
#5  0xc0d1da69 in vdead_check (vp=vp@entry=0xc4b70000, flags=flags@entry=1) at /usr/src/sys/kern/vfs_vnode.c:2091
#6  0xc0d0716e in vfs_vnode_iterator_next1 (vni=0xcdb53000, f=f@entry=0xc0b9dd82 <ffs_sync_selector>, cl=cl@entry=0xe080cf2c, do_wait=false) at /usr/src/sys/kern/vfs_mount.c:508
#7  0xc0d080f9 in vfs_vnode_iterator_next (vni=<optimized out>, f=f@entry=0xc0b9dd82 <ffs_sync_selector>, cl=cl@entry=0xe080cf2c) at /usr/src/sys/kern/vfs_mount.c:530
#8  0xc0ba1c09 in ffs_sync (mp=0xc4b28000, waitfor=3, cred=0xc3d23040) at /usr/src/sys/ufs/ffs/ffs_vfsops.c:1996
#9  0xc0d0ce4a in VFS_SYNC (mp=0xc4b28000, a=3, b=0xc3d23040) at /usr/src/sys/kern/vfs_subr.c:1587
#10 0xc0d0cf50 in sched_sync (arg=0xc441b240) at ./machine/cpu.h:77
#11 0xc0102011 in lwp_trampoline ()

I can run additional gdb commands on request.

>How-To-Repeat:

>Fix: