Panic in Xen DomU when dumping a WAPBL enabled FFSv2

[Matthias Petermann <matthias%petermann-it.de@localhost>]

Hello,

while trying to run a

    dump -0auf /tmp/root.0.dump

from inside a Xen DomU (running NetBSD 8.0_BETA) I get the following
panic console output:

    devel# dump -0auf /tmp/root.0.dump /
      DUMP: Found /dev/rxbd0a on / in /etc/fstab
      DUMP: Date of this level 0 dump: Fri Nov 24 06:20:45 2017
      DUMP: Date of last level 0 dump: the epoch
      DUMP: Dumping /dev/rxbd0a (/) to /tmp/root.0.dump
      DUMP: Label: none
      DUMP: mapping (Pass I) [regular files]
    panic: kernel diagnostic assertion "!ISSET(bp->b_oflags, BO_DONE)" 
failed: file "../../../../kern/vfs_bio.c", line 1572
    cpu0: Begin traceback...
    vpanic() at netbsd:vpanic+0x140
    nd6_hint() at netbsd:nd6_hint
    biodone() at netbsd:biodone+0xb4
    dk_done1() at netbsd:dk_done1+0x56
    xbd_handler() at netbsd:xbd_handler+0x280
    intr_biglock_wrapper() at netbsd:intr_biglock_wrapper+0x1d
    evtchn_do_event() at netbsd:evtchn_do_event+0x27d
    do_hypervisor_callback() at netbsd:do_hypervisor_callback+0x17a
    hypervisor_callback() at netbsd:hypervisor_callback+0x9e
    idle_loop() at netbsd:idle_loop+0x18c
    cpu0: End traceback...

Also, I have also seen variations of the panic looking like this:

    fatal page fault in supervisor mode
    trap type 6 code 0 rip 0xffffffff805d0714 cs 0xe030 rflags 0x10206 
cr2 0xffffa00009d4aff8 ilevel 0x8 rsp 0xffffa000b301ec18
    curlwp 0xffffa0000745f840 pid 0.2 lowest kstack 0xffffa000b301b2c0
    panic: trap
    cpu0: Begin traceback...
    vpanic() at netbsd:vpanic+0x140
    snprintf() at netbsd:snprintf
    trap() at netbsd:trap+0xbf0
    --- trap (number 6) ---
    memcpy() at netbsd:memcpy+0x14
    intr_biglock_wrapper() at netbsd:intr_biglock_wrapper+0x1d
    evtchn_do_event() at netbsd:evtchn_do_event+0x27d
    do_hypervisor_callback() at netbsd:do_hypervisor_callback+0x17a
    hypervisor_callback() at netbsd:hypervisor_callback+0x9e
    idle_loop() at netbsd:idle_loop+0x18c
    cpu0: End traceback...

The issue is reproducable any time I try.

The filesystem in question is clean and has WAPBL enabled. It is located
inside a LVM LV.

The Xen Dom0 is a NetBSD 8.0_BETA, too. The Xen Version is 4.8.

My question here is: is there some obvious thing that I am doing
wrong?

Best regards,
Matthias

--
Matthias Petermann <matthias%petermann-it.de@localhost> | www.petermann-it.de
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