defunct process occupying file set

From: LBRO <lbro_at_dscc.dk>
Date: Wed, 22 Apr 1998 15:40:45 +0100

     Hi, managers.
     
     The following is a tough one and I dont really know what to do with
     it.
     
     I have had several complaints about filesystems that cannot be
     unmounted although lsof says that no processes use files from that
     filesystem. It always shows up that there is something suspicious
     about a defunct process.
     
     cathy.dscc.dk # umount /usr/mcc
     /usr/mcc: Device busy
     
     
     cathy.dscc.dk # ps -ef
     ...
     ...
     root 12984 12985 0.0 09:30:38 ttyp6 0:00.11 -ksh (ksh)
     root 12989 12984 0.0 - ttyp6 0:00.00 <defunct>
     
     
     cathy.dscc.dk # kill -9 12984
     
     cathy.dscc.dk # umount /usr/mcc
     cathy.dscc.dk #
     
     
     lsof tells me that the process 12984 does not use anything from the
     /usr/mcc file system. Of course it does not tell me anything about the
     defunct.
     
     lsof shows the following error message:
     
     cathy.dscc.dk # lsof
     lsof: WARNING: can't stat() advfs file system /usr/mcc
           Output information may be incomplete.
     lsof: WARNING: can't form any device cache path
     ....
     
     
     I get the feeling that the defunct process although all resources
     should be deallocated still holds the file system. If that is true, I
     would say thet it is an error in the kernel. I have seen the problem
     on 3.2g as well as on 4.0d prior to dupatch #00001
     
     I have not been able to provoke this behaviour in a controlled
     environment yet but I will try and let you know.
     
     
     Any opinions ?
     
     
     Yours, Lars Bro (lbro$dscc.dk)
Received on Wed Apr 22 1998 - 15:48:26 NZST

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