Re: kern/45305: umount says device busy without any process having current directory in the mount or file open

[Matthias Kretschmer <kretschm%cs.uni-bonn.de@localhost>]

The following reply was made to PR kern/45305; it has been noted by GNATS.

From: Matthias Kretschmer <kretschm%cs.uni-bonn.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/45305: umount says device busy without any process having 
current directory in the mount or file open
Date: Tue, 6 Sep 2011 07:21:46 +0200

 Hello,
 
 it got it again ...
 
 On Mon, Aug 29, 2011 at 10:25:02AM +0000, matthew green wrote:
 >  what does "fstat" say in this case?  it should report any thing that
 >  is showing an open filesystem.  also, for the killed everything case,
 >  what processes are running?
 
 # fstat
 USER     CMD          PID   FD MOUNT       INUM MODE         SZ|DV R/W
 root     fstat      18085   wd /          31885 drwxr-xr-x     512 r 
 root     fstat      18085    0 /          53128 crw-------   ttyE0 rw
 root     fstat      18085    1 /          31999 -rw-r--r--       0 w 
 root     fstat      18085    2 /          53128 crw-------   ttyE0 rw
 root     fstat      18085    3 /          53828 crw-r-----     mem r 
 root     fstat      18085    4 /          53827 crw-r-----    kmem r 
 root     fstat      18085    5 /          53826 crw-r-----    drum r 
 root     fstat      18085    6 /            377 -rw-------   40960 r 
 root     sh          4953   wd /          31885 drwxr-xr-x     512 r 
 root     sh          4953    0 /          53128 crw-------   ttyE0 rw
 root     sh          4953    1 /          53128 crw-------   ttyE0 rw
 root     sh          4953    2 /          53128 crw-------   ttyE0 rw
 root     sh          4953  127 /          53833 crw-rw-rw-     tty rw
 root     login      23308   wd /          31885 drwxr-xr-x     512 r 
 root     login      23308    0 /          53128 crw-------   ttyE0 rw
 root     login      23308    1 /          53128 crw-------   ttyE0 rw
 root     login      23308    2 /          53128 crw-------   ttyE0 rw
 root     init           1   wd /              2 drwxr-xr-x     512 r 
 root     system         0   wd /              2 drwxr-xr-x     512 r 
 
 # ps ax
   PID TTY   STAT     TIME COMMAND
     0 ?     DKl  10:46.21 [system]
     1 ?     Is    0:00.71 init 
  4953 ttyE0 S     0:02.82 -sh 
 23308 ttyE0 Is    0:00.54 login 
 25680 ttyE0 O+    0:00.01 ps -ax 
 
 # umount /netboot
 umount: /netboot: Device busy
 
 
 So as you can see, there is no process running which has any access
 to /netboot, even though it cannot be unmounted.
 The corresponding /netboot entry from fstab:
 <host>:/home/macppc/root  /netboot  nfs  rw,noauto
 
 
 --
 Matthias Kretschmer