[wplug] kill QUESTION -> mount question

[Robert E. Coutch]

This brings me to a variation of my last question.

The unmountable mount.

I've had memory cards, CDROM's and ZIP disks do this at different times.

I use lsof and it shows no files open on the device.
I run umount (as root) as it says device in use can not umount.

I run umount -f and the system states device not mounted in mtab.

I run mount and it shows the device still mounted.

I usually wind up rebooting when this happens (which is not very often).

Is it possible to force a umount on a device even while it's in use.
I understand the risks but sometimes "you gotta do what you gotta do".

NOW BACK TO THE FIRST TOPIC........

Is there a way to get rid of a sleeping or zombie process other than by a 
reboot?


Thanks,

Bob


On Thursday 24 June 2004 08:58 am, Poyner, Brandon wrote:
> No process can ignore a kill -9 (SIGKILL), but if the process is in an
> uninterruptible sleep the kill signal will not be delivered until the
> process wakes up.  A process performing disk i/o, which normally is a
> very short term event, is uninterruptible to avoid data errors.  If the
> i/o doesn't complete or give up (like when using a nfs 'soft' mount) the
> process will never receive the SIGKILL because it's in the queue behind
> the i/o request.  You might be able to 'umount -f' the partition, I'm
> not sure if Linux permits that on non-nfs mount points but the *BSDs do.
> If the partition goes away the kernel should inform the process that the
> i/o cannot be completed, it will then wake up and die.
>
> Brandon Poyner
> Network Engineer II
> CCAC - College Office
> 412-237-3086
>
>
> -----Original Message-----
> From: Robert E. Coutch [mailto:robert.coutch at verizon.net]
> Sent: Thursday, June 24, 2004 12:12 AM
> To: wplug at wplug.org
> Subject: Re: [wplug] kill QUESTION
>
>
> Is there a way to kill an "unkillable" process?
>
> Let's say I have to kill a hanging process no matter what the risk.
>
> Every once in a while a process freezes (sleeps, wait, or whatever you
> want to
> call it) and only a reboot gets things back in order.
> Sometimes a hard reboot is necessary because the hanging process affects
>
> shutdown.
>
> I had this happen in the past and wondered if there was some other way
> besides
> a reboot to kill a process.
>
> -Bob
>
> On Wednesday 23 June 2004 02:34 pm, Poyner, Brandon wrote:
> > That sounds like the process is in an uninterruptible sleep, which is
> > usually caused by a process waiting on i/o.  You can't use kill to end
> > such a process.  If you run a ps and grep on the process, look at the
> > stat field.  If the stat is showing a D then it is in an
>
> uninterruptible
>
> > sleep (check the ps man page for other STATs).
> >
> > USER       PID %CPU %MEM   VSZ  RSS TTY      STAT START   TIME COMMAND
> > bpoyner  16928  0.0  0.1  4564 1432 pts/0    S    14:02   0:00 -bash
> >
> > If that's the issue the drive is most likely going bad or is
>
> improperly
>
> > connected.  I'd download the diagnostic tool from the drive
>
> manufacturer
>
> > to be sure.
> >
> > Brandon Poyner
> > Network Engineer II
> > CCAC - College Office
> > 412-237-3086
> >
> >
> > -----Original Message-----
> > From: Logan [mailto:lws118 at psu.edu]
> > Sent: Wednesday, June 23, 2004 1:22 PM
> > To: wplug at wplug.org
> > Subject: [wplug] kill
> >
> >
> > What can I do if "# kill -9 $pid" doesn't work?
> > I've been having immense difficulties with a new (to this computer)
>
> hard
>
> > disk.
> > The disk is supposed to be just for backups, and is mounted with a
> > script, the
> > backups run, and then it's unmounted.
> >
> > It sometimes works ok, but at other times I try stuff like "ls
> > /root/backups"
> > (where it's mounted) and ls freezes. I can't kill the process, and
> > therefore
> > can't unmount the drive. It's not just ls either, cp didn't work - and
> > it just
> > hangs there. Even tab completion freezes up "cat ~/backups/<tab>"
> > freezes it.
> >
> > When I tell the computer to reboot, it doesn't do that either. I get a
> > new
> > process called "[shutdown] <defunct>" after the "shutdown -r 0 w"
> > process.
> >
> >
> > The partition on /dev/hdb1, formated as reiserfs (my root directory
>
> and
>
> > RAID 0
> > are both reiserfs too, no problems with them)
> > I don't suspect there's anything wrong with the physical drive. It was
> > in my
> > parent's computer until they upgraded and had always worked fine.
> >
> >
> >
> > The Internet treats censorship as a malfunction and routes around it.
> > 	John Perry Barlow.
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> > wplug at wplug.org
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> >
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