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User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050317 Firefox/1.0.6

Description of problem:
When trying to unmount a file system which is exported by NFS to a large number of heterogeneous clients, the unmounting is denied:

umount: /d1: device is busy

/var/log/messages contains the following traces at the time of the umount:

Aug 31 08:24:36 ganlxsr3 rpc.statd[921]: Received erroneous SM_UNMON
request from ganlxsr3 for 193.x.y.z
Aug 31 08:24:36 ganlxsr3 kernel: lockd: couldn't shutdown host module!

No processs seem to be using that filesystem at the moment we tried to unmount it:

# lsof | grep d1
#

Gives nothing.

The problem we also see related to that issue, is that the [lockd] daemon which is now running correctly wasn't there in the list of process

# ps auxww | grep lockd
#
Gives nothing



Version-Release number of selected component (if applicable):
kernel 2.4.21-32.0.1.ELsmp

How reproducible:
Sometimes

Steps to Reproduce:
1. Wait a sufficient amount of time (some days/weeks)
2. unexport /d1
3. try to umount /d1
4. buzy message as above
  

Actual Results:  file system remains mounted

Expected Results:  file system should have been unmounted without error

Additional info: