Xen users - Jul 2009 - xen-tools: does not unmount disks and mounts proc into the new VM - why?

Hi!

I am using xen-tools version: 3.9-4 to create domUs:

1. time xen-create-image --verbose --dist=lenny
--install-source=/mnt/xen-file-images/lenny-64-template-debootstrap-30Jun09-fix2.tar
--hostname dummy --ip xxx.xxx.xxx.xxx --force

2. xm create dummy.cfg

Then I get the message 

Device /dev/vg0/dummy-disk is mounted in the privileged domain,
and so cannot be mounted by a guest.

3. When I tried to umount, I got "device busy".

4. I am really surprised about the output of mount on my dom0:


dom0:~# mount
/dev/sda1 on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
procbususb on /proc/bus/usb type usbfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/mapper/vg0-linux--images on /mnt/linux-images type xfs (rw)
/dev/mapper/vg0-xen--file--images on /mnt/xen-file-images type xfs (rw)
/dev/mapper/vg0-dummy--disk on /tmp/1UNYuVP7WO type ext3 (rw)
/proc on /tmp/1UNYuVP7WO/proc type none (rw,bind)


Why is /proc mounted to /tmp/1U.... that is in fact the disk of the new
VM? That looks really dangerous. 

Did anybody see this before?

I used --force because on the first call I did a mistake and the logical
volumes already existed. Maybe --force is not a good idea?

Thanks,
  Alex







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Alexander Menk wrote:
> Hi!
>
> I am using xen-tools version: 3.9-4 to create domUs:
>
> 1. time xen-create-image --verbose --dist=lenny
>
--install-source=/mnt/xen-file-images/lenny-64-template-debootstrap-30Jun09-fix2.tar
--hostname dummy --ip xxx.xxx.xxx.xxx --force
>
> 2. xm create dummy.cfg
>
> Then I get the message 
>
> Device /dev/vg0/dummy-disk is mounted in the privileged domain,
> and so cannot be mounted by a guest.
>
> 3. When I tried to umount, I got "device busy".
>
> 4. I am really surprised about the output of mount on my dom0:
>
>
> dom0:~# mount
> /dev/sda1 on / type ext3 (rw,errors=remount-ro)
> tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
> proc on /proc type proc (rw,noexec,nosuid,nodev)
> sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
> procbususb on /proc/bus/usb type usbfs (rw)
> udev on /dev type tmpfs (rw,mode=0755)
> tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
> devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
> /dev/mapper/vg0-linux--images on /mnt/linux-images type xfs (rw)
> /dev/mapper/vg0-xen--file--images on /mnt/xen-file-images type xfs (rw)
> /dev/mapper/vg0-dummy--disk on /tmp/1UNYuVP7WO type ext3 (rw)
> /proc on /tmp/1UNYuVP7WO/proc type none (rw,bind)
>
>
> Why is /proc mounted to /tmp/1U.... that is in fact the disk of the new
> VM? That looks really dangerous. 
>
> Did anybody see this before?
>
> I used --force because on the first call I did a mistake and the logical
> volumes already existed. Maybe --force is not a good idea?
I would check to see if a process, like sshd, got started in the chroot 
that xen-tools created. Having something running there could keep the 
host from being able to unmount the volumes. I ran into this problem and 
it was something starting in the chroot. Hope that helps.

mike

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something similar happened to me a couple of times, when  
xen-create-image hung: I don''t know how debootstrap works, but I  
suppose the disk image needs to be mounted and chrooted to install the  
system. So the /proc mounted on /tmp refers to the domU, and if the  
xen-create-image script is halted, I suppose is it safe to umount it  
with:

umount /tmp/1UNYuVP7WO/proc

...you should then umount the domU disk image without problems.

Max.

Quoting Alexander Menk <alex.menk.lists2@googlemail.com>:
> Hi!
>
> I am using xen-tools version: 3.9-4 to create domUs:
>
> 1. time xen-create-image --verbose --dist=lenny
>
--install-source=/mnt/xen-file-images/lenny-64-template-debootstrap-30Jun09-fix2.tar
--hostname dummy --ip xxx.xxx.xxx.xxx
> --force
>
> 2. xm create dummy.cfg
>
> Then I get the message
>
> Device /dev/vg0/dummy-disk is mounted in the privileged domain,
> and so cannot be mounted by a guest.
>
> 3. When I tried to umount, I got "device busy".
>
> 4. I am really surprised about the output of mount on my dom0:
>
>
> dom0:~# mount
> /dev/sda1 on / type ext3 (rw,errors=remount-ro)
> tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
> proc on /proc type proc (rw,noexec,nosuid,nodev)
> sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
> procbususb on /proc/bus/usb type usbfs (rw)
> udev on /dev type tmpfs (rw,mode=0755)
> tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
> devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
> /dev/mapper/vg0-linux--images on /mnt/linux-images type xfs (rw)
> /dev/mapper/vg0-xen--file--images on /mnt/xen-file-images type xfs (rw)
> /dev/mapper/vg0-dummy--disk on /tmp/1UNYuVP7WO type ext3 (rw)
> /proc on /tmp/1UNYuVP7WO/proc type none (rw,bind)
>
>
> Why is /proc mounted to /tmp/1U.... that is in fact the disk of the new
> VM? That looks really dangerous.
>
> Did anybody see this before?
>
> I used --force because on the first call I did a mistake and the logical
> volumes already existed. Maybe --force is not a good idea?
>
> Thanks,
>   Alex
>
>
>
>
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>
>


Massimiliano De Ruosi
---------------------
C.S.I.T. (Centro Servizi Informatici e Telematici)
Universita'' degli Studi di Udine
Via delle Scienze, 208
33100, Udine (UD)  ITALY

Tel.  +39 (0)432 55 8893
Cell. +39 320 4350861
Fax:  +39 (0)432 55 8911 (segr. CSIT)
email: massimiliano.deruosi@uniud.it

----------------------------------------------------------------------
SEMEL (SErvizio di Messaging ELettronico) - CSIT -Universita'' di Udine



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