panic: existing znode 0xffffff012629a178 for dbuf 0xffffff003bf99540

[Kris Kennaway]

I got this from stress2 on a zfs pool from an up-to-date 8.0 system:

buf.15140:      existing znode 0xffffff012629a178 for dbuf 
0xffffff003bf99540

panic() at panic+0x17b
zfs_znode_dmu_init() at zfs_znode_dmu_init+0xb5
zfs_znode_alloc() at zfs_znode_alloc+0xa0
zfs_mknode() at zfs_mknode+0x205
zfs_freebsd_create() at zfs_freebsd_create+0x617
VOP_CREATE_APV() at VOP_CREATE_APV+0xb3
[...]

Unfortunately the console is broken so I can't get more of the 
backtrace.  Any ideas?

Kris