crash and panic using pfsync on 13.1-RELEASE (Bug 268246)

Hi folks -- I opened this on Freebsd 13.1.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268246

I'm stumped, as I have about half a dozen other systems just like this one,
which do not exhibit this condition.

Don't know if it matters, but this is the backup firewall in a carp
configuration.


kgdb /usr/lib/debug/boot/kernel/kernel.debug /var/crash/vmcore.0

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x18
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff80cadb90
stack pointer           = 0x28:0xfffffe0204794bc0
frame pointer           = 0x28:0xfffffe0204794c20
code segment            = base r
<https://svnweb.freebsd.org/changeset/base/>x0, limit 0xfffff, type
0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 12 (swi1: pfsync)
trap number             = 12
panic: page fault
cpuid = 0
time = 1670433489
KDB: stack backtrace:
#0 0xffffffff80c694a5 at kdb_backtrace+0x65
#1 0xffffffff80c1bb5f at vpanic+0x17f
#2 0xffffffff80c1b9d3 at panic+0x43
#3 0xffffffff810afdf5 at trap_fatal+0x385
#4 0xffffffff810afe4f at trap_pfault+0x4f
#5 0xffffffff810875b8 at calltrap+0x8
#6 0xffffffff80dca82f at ip_fragment+0x24f
#7 0xffffffff80dca1e3 at ip_output+0x1163
#8 0xffffffff8225a851 at pfsyncintr+0x151
#9 0xffffffff80bdbcfa at ithread_loop+0x25a
#10 0xffffffff80bd8a9e at fork_exit+0x7e
#11 0xffffffff8108862e at fork_trampoline+0xe
Uptime: 43m36s
Dumping 7356 out of 130983 MB:..1%..11%..21%..31%..41%..51%..61%..71%..81%..91%