mount: could not find any free loop device

[Andras Simon]

On 6/27/07, Luciano Rocha <strange at nsk.no-ip.org> wrote:
> On Wed, Jun 27, 2007 at 12:28:28AM +0200, Andras Simon wrote:
> >  I'm trying to
> >
> >  mount -o loop,offset=32256 /usr/local/kvm-images/WinXP.raw /mnt/
> >
> >  as I've done successfully several times before, but now I get
> >
> >  mount: could not find any free loop device
> >
> >  What can possibly use loop devices? There are eight processes called
> >  loop0 through loop7, all started by kthread. But I've no idea what
> >  they do and if it's them who are using the loop devices.
>
> They're the one serving the loop devices in use. So you exausted the
> free loop devices. Free one (umount any in use) and try again.

The problem is that there shouldn't be any loop devices in use and
there's nothing to unmount. The following transcript demonstrates the
problem:

[root at localhost ~]# losetup -a
[root at localhost ~]# mount -o loop,offset=32256
/usr/local/kvm-images/WinXP.raw /mnt/
[root at localhost ~]# umount /mnt/
[root at localhost ~]# losetup -a
/dev/loop0: [080c]:14073859 (/usr/local/kvm-images/WinXP.raw), offset 32256


> You can see what is being used by a loop device with losetup:
> # losetup /dev/loop0
> /dev/loop0: [fd06]:234921356 (/linux/isos/backtrack.iso)

Yes, I used losetup to find the culprit (and get rid of it), see my
previous mail.
man -k can sometimes be very handy :-)

Thanks,
Andras