kern/39199: ppp-related crash during shutdown

[apb%cequrux.com@localhost]

>Number:         39199
>Category:       kern
>Synopsis:       ppp-related crash during shutdown
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jul 23 18:55:00 +0000 2008
>Originator:     Alan Barrett
>Release:        NetBSD 4.99.69
>Organization:
Not much
>Environment:
System: NetBSD 4.99.69
Architecture: i386
Machine: i386
>Description:
    The system crashed during shutdown.

    At the time, pppd was running over a serial port on a PCMCIA modem
    card.
        
>How-To-Repeat:
    Insert PCMCIA modem card.

    Run pppd over the com port on the modem card.

    shutdown -p now (or perhaps it was shutdown -r now; I don't remember)
    [...]
    Done running shutdown hooks.
    tap0 detached [unrelated to this problem, I assume]
    uvm_fault(0xc088b040, 0xdeadb000, 1) -> 0xe
    fatal page fault in supervisor mode
    trap type 6 code 0 eip c01e9465 cs 8 eflags 10282 cr2 deadbeff ilevel 6
    kernel: supervisor trap page fault, code = 0
    Stopped in pid 1535.1 (pppd) at netbsd:pfi_ihead_RB_REMOVE+0x25: movl
    0
    x10(%edx),%eax
    db{1}> bt
    pfi_ihead_RB_REMOVE ...
    pfi_kif_unref ...
    pfi_detach_ifgroup ....
    if_delgroup ...
    pfi_destroy_groups ...
    pfil_ifnet_wrapper ...
    pfil_run_hooks ...
    if_detach ...
    ppp_clone_destroy ...
    pppclose ...
    ttioctl ...
    [...]

>Fix:
    Unknown