Odd 'hang' trying to ls a directory ...

[Marc G. Fournier]

Running -STABLE from May 15th, if I do an 'ls /usr', it works ... if I do
an 'ls /vm', it hangs .. the machine doesn't hang, as far as I can tell,
all the web sites are accessible, and there are no errors in
/var/log/messages .. I have soft-updates disabled on that file system, and
iostat is showing the drive array to be quite idle:

      tty             da0            pass0            pass1             cpu
 tin tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
   0   35  0.00   0  0.00   0.00   0  0.00   0.00   0  0.00  13  0 14  1 73
   0    8  9.62  30  0.28   0.00   0  0.00   0.00   0  0.00   4  0  3  0 93
   0    8 15.00   2  0.03   0.00   0  0.00   0.00   0  0.00   7  0  1  0 92
   0    8 15.00   4  0.06   0.00   0  0.00   0.00   0  0.00   3  0  1  0 96
   0    8 15.77  30  0.46   0.00   0  0.00   0.00   0  0.00   0  0  2  0 97

I can run 'df', but I can't run 'df -t ufs', as that too just hangs ...

According to ps axl, I have the following in WCHAN states:

neptune# ps axl | awk '{print $9}' | sort | uniq -c
   6 -
   1 WCHAN
 207 accept
 103 inode
   2 kqread
 412 lockf
  68 nanslp
   8 pause
   1 piperd
  13 poll
   3 psleep
  58 sbwait
   1 sched
 626 select
   1 syncer
   3 ttyin
   1 vlruwt
   8 wait

Thoughts?  Does anything above look like its 'hanging' or 'locking' the file
system?  A few minutes later, there are a few variations:

neptune# ps axl | awk '{print $9}' | sort | uniq -c
   6 -
   1 WCHAN
 207 accept
 129 inode
 426 lockf
  67 nanslp
   8 pause
   1 piperd
  13 poll
   3 psleep
  61 sbwait
   1 sched
 622 select
   1 syncer
   3 ttyin
   1 vlruwt
   9 wait