#18 umount: device is busy

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nobody
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2002-10-09
2002-10-09
Timothee Besset
No

Ok, I don't know how I ended up in this situation
exactly. It involved lufsd debugging, some mounted
filesystems, a crash in lufsd

Anyway, I end up with a directory that can not be
unmounted:
umount: blah: device is busy

I carefully checked that all processes which may have
been locking stuff in there are dead (including the
lufs daemon)

and:
Module Size Used by Not tainted
lufs 13152 3

I can't rmmod lufs, I can umount that dir either .. I
feel kinda stuck into rebooting now :-)

what kind of solution could we have to prevent stalls
like that, or diagnose the kernel module, etc.? maybe
we could have something in /proc ?

Discussion

  • Logged In: NO

    I had the same problem, but managed to unmount with the command:

    umount -f /mount/point

    Does it works for you?

     
  • Logged In: YES
    user_id=2063

    yeah .. that's what I'd rather avoid .. last time I did
    that, my kernel hardlocked a few seconds afterwards

    I'm compiling a new kernel and I'm gonna reboot the server
    anyway .. so much for the uptime, but I had to do that
    anyway :-)

    would be nice to have some way to diagnose next time the
    situation happens

     
  • Logged In: YES
    user_id=2063

    this is happening again
    I had written a lengthy report but a navigator screwup lost it

    basically:

    timo@akira:/home/doom-grp$ lufsumount Doom-ftp/
    could not umount /home/doom-grp/Doom-ftp: Device or resource
    busy
    timo@akira:/home/doom-grp$ fuser -m Doom-ftp/
    Doom-ftp/: 22413
    timo@akira:/home/doom-grp$ ps aux | grep 22413
    timo 22413 0.0 0.6 9076 808 ? D 16:14
    0:01 /sbin/mount.lufs none ./Doom-cachefs/ -o fs=cachefs
    root=/home/doom-grp/Doom-ftp dmask=777 fmask=777
    cache=/home/doom-grp/Doom

    but, this is a parasite mount.lufs, the only valid
    mount.lufs is the one dealing with that directory I try to
    unmount.

    /tmp/lufsdaHxbI7
    fuser /tmp/lufsdaHxbI7
    /tmp/lufsdaHxbI7: 22395 22397 22398

    so that other lufs seems to be disconnected with the kernel
    pair?

    and worse .. 22413 is kernel locked .. situation blocked!

    this is probably happening because I am cascading the
    filesystems, my cachefs looks into a reference directory
    that happens to be an ftpfs ..

     
  • Logged In: YES
    user_id=2063

    could the channels settings have any importance in this?

     
  • Logged In: YES
    user_id=2063

    still happening with 0.8.1 code (current cvs)

    for now, I only got this happening when I mount an lufs over
    samba from another machine. so I suppose samba's behaviour
    with the file system is causing this. I'll probably use this
    some more natively so I could tell for sure.

     
  • Logged In: YES
    user_id=2063

    Still there in 0.9.3
    This time it doesn't happen when I use Samba over an lufs
    mounted ftpfs. It is much more common.

    umount says "device is busy"
    fuser -m mounted-dir/. hangs, it doesn't return

    I think this is happening because on program I have
    accessing the ftpfs dies with a segfault during operation.