kern/132337: [zfs] [panic] kernel panic in zfs_fuid_create_cred

[Thomas Backman]

Hey all,
Unfortunately, this PR appears to still be unfixed. Is anyone looking  
at this?
I tried to set up a diskless client over NFS yesterday, running ZFS  
on /, and ran in to this panic (exact same backtrace as the PR (see  
bottom the this mail)) a lot of times. In the end, I created a ZVOL  
with UFS on it, and the panics disappeared as expected - since it no  
longer has to work directly with files on a ZFS *filesystem*.
It seems to be pretty easy to trigger, as I couldn't finish the boot  
process on the diskless client more than once until I went with UFS.  
Since then I've gotten 0 panics.

FWIW, my /etc/exports (I know now R/W NFS root isn't a good idea, but  
it might be relevant):
/diskless -maproot=0 -alldirs 192.168.1.6

Regards,
Thomas

Backtrace:

panic: zfs_fuid_create_cred
cpuid = x
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
panic() at panic+0x182
zfs_fuid_create_cred() at zfs_fuid_create_cred+0x56
zfs_perm_init() at zfs_perm_init+0x84
zfs_mknode() at zfs_mknode+0x24e
zfs_freebsd_create() at zfs_freebsd_create+0x617
VOP_CREATE_APV() at VOP_CREATE_APV+0xb3
nfsrv_create() at nfsrv_create+0x909
nfssvc_program() at nfssvc_program+0x1a1
svc_run_internal() at svc_run_internal+0x62b
svc_thread_start() at svc_thread_start+0xb
fork_exit() at fork_exit+0x12a
fork_trampoline() at fork_trampoline+0xe