[linux-lvm] lvremove hangs on removing snapshot

[linux-lvm] lvremove hangs on removing snapshot

[Joris van Rantwijk]

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.

Re: [linux-lvm] lvremove hangs on removing snapshot

[Alasdair G Kergon]

On Sun, Jun 04, 2006 at 09:01:07PM +0200, Joris van Rantwijk wrote:
> My system is Debian 3.1, linux 2.6.16.16, lvm2 2.01.04.

Upgrade userspace:
  2.6.16+ requires 2.02.*

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] lvremove hangs on removing snapshot

[Joris van Rantwijk]

On Mon, Jun 05, 2006 at 09:04:16PM +0100, Alasdair G Kergon wrote:
> > My system is Debian 3.1, linux 2.6.16.16, lvm2 2.01.04.
> Upgrade userspace:
>   2.6.16+ requires 2.02.*

Yep, this seems to fix the problem. Thanks for your help.

Bye,
  Joris.