Kernel panic in 5.99.11

[Martti Kuparinen <martti.kuparinen%iki.fi@localhost>]

I upgraded my domU to 5.99.11 and I get this during boot:

NetBSD 5.99.11 (XEN3PAE_DOMU) #0: Fri May 15 09:13:10 EEST 2009
...
boot device: xbd0
root on xbd0a dumps on xbd0b
mountroot: trying smbfs...
mountroot: trying ntfs...
mountroot: trying nfs...
mountroot: trying msdos...
mountroot: trying lfs...
mountroot: trying ext2fs...
mountroot: trying ffs...
root file system type: ffs
init: copying out path `/sbin/init' 11
Fri May 15 09:59:55 EEST 2009
Starting root file system check:
** /dev/rxbd0a
** File system is clean; not checking
swapctl: adding /dev/xbd0b as swap device at priority 0
Starting file system checks:
/dev/rxbd0a: file system is mounted read-write on /; not checking
Automatic file system check failed; help!
ERROR: ABORTING BOOT (sending SIGTERM to parent)!
1 2009-05-15T09:59:55.739581+03:00 - init - - - `/bin/sh' on `/etc/rc' 
terminated abnormally, going to single user mode
Enter pathname of shell or RETURN for /bin/sh:


Next I rebooted to single-user mode and ran

# fsck -y -f /
** /dev/rxbd0a
** File system is already clean
** Last Mounted on /
** Root file system
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
204478 files, 2234652 used, 2848251 free (15611 frags, 354080 blocks, 0.3% 
fragmentation)
# exit
Fri May 15 10:03:54 EEST 2009
Starting root file system check:
** /dev/rxbd0a
** File system is clean; not checking
swapctl: adding /dev/xbd0b as swap device at priority 0
Starting file system checks:
/dev/rxbd0a: file system is mounted read-write on /; not checking
Automatic file system check failed; help!
Setting tty flags.
Setting sysctl variables:
ddb.onpanic: 1 -> 0
Starting network.
Hostname: n38.nomadiclab.com
IPv6 mode: autoconfigured host
Configuring network interfaces: xennet0.
Adding interface aliases:.
add net default: gateway 193.234.219.1
Sending router solicitation...
Building databases: dev, utmp, utmpx done
Starting syslogd.
Setting date via ntp.
Checking for core dump...
savecore - - - no core dump
Starting rpcbind.
Mounting all filesystems...
Clearing temporary files.
Creating a.out runtime link editor directory cache.
Checking quotas: done.
Starting mountd.
Starting nfsd.
uvm_fault(0xc049c200, 0xca157000, 2) -> 0xe
fatal page fault in supervisor mode
trap type 6 code 3 eip c0333bce cs 9 eflags 10282 cr2 ca1570b0 ilevel 0
panic: trap
Begin traceback...
End traceback...

dumping to dev 142,1 offset 534591
dump device bad

Next I downgraded the kernel back to 5.99.9 and

# fsck -y -f /
** /dev/rxbd0a
** Last Mounted on /
** Root file system
** Phase 1 - Check Blocks and Sizes
INCORRECT BLOCK COUNT I=227912 (4 should be 0)
CORRECT? yes

** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
LINK COUNT FILE I=227239  OWNER=0 MODE=100644
SIZE=94208 MTIME=May 15 10:03 2009  COUNT 2 SHOULD BE 1
ADJUST? yes

LINK COUNT FILE I=227322  OWNER=0 MODE=100444
SIZE=33 MTIME=May 15 10:04 2009  COUNT 2 SHOULD BE 1
ADJUST? yes

UNREF FILE I=227912  OWNER=0 MODE=100644
SIZE=0 MTIME=May 15 10:03 2009
CLEAR? yes

** Phase 5 - Check Cyl groups
FREE BLK COUNT(S) WRONG IN SUPERBLK
SALVAGE? yes

SUMMARY INFORMATION BAD
SALVAGE? yes

BLK(S) MISSING IN BIT MAPS
SALVAGE? yes

204481 files, 2234649 used, 2848254 free (15606 frags, 354081 blocks, 0.3% 
fragmentation)

MARK FILE SYSTEM CLEAN? yes


***** FILE SYSTEM MARKED CLEAN *****

***** FILE SYSTEM WAS MODIFIED *****
# exit


and it works again. Any ideas?

Martti