hard hangs sometime after 22nd April and mutex problems

[Geoff Wing <gcw%pobox.com@localhost>]

On i386 SMP I've been getting hard hangs - no response, pings, can't break
into ddb - since sometime after the 22nd April.

Also, I've had this panic quite a few times (may precede the 22nd).
The crash dump can't backtrace on it properly (corrupted stack at
mutex_exit) so this is a hand copy from the screen.

  mutex_exit    +0xc
  soabort       +0x60
  soclose       +0x8e
  soo_close     +0x25
  closef        +0xe0
  fd_close      +0x1ef
  fd_free       +0xa2
  exit1         +0x218
  exit1
  syscall       +0x134

Any clues anyone?

Regards,
Geoff