[linux-lvm] lvremove hangs on removing snapshot

[Joris van Rantwijk <jvrantwijk@xs4all.nl>]

Hello,

When trying to remove a dm-snapshot device, I see lvremove freezing.
A reboot is then needed to get the system in a usable state again.

I know that previous freezes/segfaults on removing a snapshot
have been traced to a problem with kcopyd, but I am running
linux 2.6.16.16 which should contain the fix for these problems.
So it seems that my problem is different.

The freeze happens consistently, and even if the snapshot and/or
real device have not been accessed. For example, I type:

# lvcreate --size 1G --snapshot --name homesnap vg0/home
# lvremove vg0/home
Are you sure ... ? Y
 [ lvremove now frozen ]

If a filesystem was mounted on the original vg0/home, any attempt
to access the filesystem will freeze as well. Other than that, the
system remains responsive.

After a reboot, I see that vg0/home and vg0/homesnap are both still
present but set to inactive. I can then lvremove vg0/homesnap and
lvchange vg0/home to reactivate it.

If I strace lvremove on its one-way trip, I see that it sends
a few DM_SUSPEND ioctls, then freezes on a DM_TABLE_LOAD ioctl.

Am I doing something wrong with the snapshot, or is this still a bug?
I seem to remember that I had it working correctly some time ago, but
now it fails all the time.
My system is Debian 3.1, linux 2.6.16.16, lvm2 2.01.04.

Thanks,
  Joris.