6.0-BETA2 reboots when issuing "zpool create"

[Joel Carnat <joel%carnat.net@localhost>]

Hello,

I'm trying ZFS on NetBSD and it reboots each time I try to create the zpool.

I have installed "NetBSD 6.0_BETA2 (GENERIC) amd64" in a VMware ESXi virtual 
machine.
I configured a 8GB virtual disk on which I installed NetBSD using UFS.
I attached two 4GB virtual disks on which I plan to install the ZFS.
I have configured 2 vCPU and 4GB of RAM.

I have the sd0 configured the "MBR-way" by the installer and did configure sd1 
& sd2 using the "GPT-way", by hand. Here's my configuration:

NetBSD installed on sd0 :
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:  16241715        63     4.2BSD   2048 16384     0  # (Cyl.      0*-   1011*)
 b:    535438  16241778       swap                     # (Cyl.   1011*-   1044*)
 c:  16777153        63     unused      0     0        # (Cyl.      0*-   1044*)
 d:  16777216         0     unused      0     0        # (Cyl.      0 -   1044*)

Nothing yet on sd1 & sd2:
5 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 d:   8388608         0     unused      0     0        # (Cyl.      0 -    522*)
 e:   8388607         1    unknown                     # (Cyl.      0*-    522*)
5 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 d:   8388608         0     unused      0     0        # (Cyl.      0 -    522*)
 e:   8388607         1    unknown                     # (Cyl.      0*-    522*)

# gpt show sd0 sd1 sd2
     start      size  index  contents
         0         1         MBR
         1        62         
        63  16777153      1  MBR part 169
    start     size  index  contents
        0        1         PMBR
        1        1         Pri GPT header
        2       32         Pri GPT table
       34  8388541      1  GPT part - 516e7cba-6ecf-11d6-8ff8-00022d09712b
  8388575       32         Sec GPT table
  8388607        1         Sec GPT header
    start     size  index  contents
        0        1         PMBR
        1        1         Pri GPT header
        2       32         Pri GPT table
       34  8388541      1  GPT part - 516e7cba-6ecf-11d6-8ff8-00022d09712b
  8388575       32         Sec GPT table
  8388607        1         Sec GPT header

I used the GUID type from FreeBSD-ZFS as I couldn't find the alias from `gpt` 
manpage.

# dkctl sd1 listwedges 
/dev/rsd1d: 1 wedge:
dk0: 35dae1b9-abef-11e1-99f6-005056915a7c, 8388541 blocks at 34, type: 
# dkctl sd2 listwedges 
/dev/rsd2d: 1 wedge:
dk1: 36cd77b7-abef-11e1-99f6-005056915a7c, 8388541 blocks at 34, type: 

To create the ZFS pool, I run:
# zpool create tank /dev/dk0 /dev/dk1

Then NetBSD reboots. In the logs, I can see:
Jun  1 15:47:51 znetbsd /netbsd: WARNING: ZFS on NetBSD is under development
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl called 
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl -> zvol_ioctl
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl called 
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl -> zvol_ioctl
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl -> calling zfs_ioc_vec zvec_func 
on 4
Jun  1 15:48:08 znetbsd /netbsd: zfsdev_ioctl 0
Jun  1 15:50:12 znetbsd syslogd[356]: restart
Jun  1 15:50:12 znetbsd /netbsd: zfsdev_ioctl called 
Jun  1 15:50:12 znetbsd /netbsd: zfsdev_ioctl -> zvol_ioctl
Jun  1 15:50:12 znetbsd /netbsd: zfsdev_ioctl -> calling zfs_ioc_vec zvec_func 
on 0
Jun  1 15:50:12 znetbsd /netbsd: vnode @ 0xfffffe81082af170, flags 
(0x30<MPSAFE,LOCKSWORK>)
Jun  1 15:50:12 znetbsd /netbsd:        tag VT_UFS(1), type VBLK(3), usecount 
1, writecount 1, holdcount 0
Jun  1 15:50:12 znetbsd /netbsd:        freelisthd 0x0, mount 
0xfffffe810753e000, data 0xfffffe81088aea00 lock 0xfffffe81082af280
Jun  1 15:50:12 znetbsd /netbsd:        tag VT_UFS, ino 757668, on dev 4, 0 
flags 0x0, nlink 1
Jun  1 15:50:12 znetbsd /netbsd:        mode 060640, owner 0, group 5, size 0
Jun  1 15:50:12 znetbsd /netbsd: panic: vrelel: bad ref count
Jun  1 15:50:12 znetbsd /netbsd: cpu1: Begin traceback...
Jun  1 15:50:12 znetbsd /netbsd: vfs_vnode_sysinit() at netbsd:vfs_vnode_sysinit
Jun  1 15:50:12 znetbsd /netbsd: vrelel() at netbsd:vrelel+0x204
Jun  1 15:50:12 znetbsd /netbsd: vdev_disk_open() at zfs:vdev_disk_open+0x173
Jun  1 15:50:12 znetbsd /netbsd: cpu1: End traceback...
Jun  1 15:50:12 znetbsd /netbsd: 
Jun  1 15:50:12 znetbsd /netbsd: dumping to dev 4,1 offset 8
Jun  1 15:50:12 znetbsd /netbsd: dump failed: insufficient space (535438 < 
8387713)
Jun  1 15:50:12 znetbsd /netbsd: 
Jun  1 15:50:12 znetbsd /netbsd: 
Jun  1 15:50:12 znetbsd /netbsd: rebooting...

Am I doing something wrong or is this a bug ?

TIA,
        Jo