Bug#659762: lvm2: LVM commands freeze after snapshot delete fails

[Paul LeoNerd Evans]

Package: lvm2
Version: 2.02.88-2
Severity: normal

Tried and failed to remove an LVM snapshot:


root at cel:~
# lvremove vg_cel/backups-20110930
Do you really want to remove active logical volume backups-20110930? [y/n]: ^C
  Logical volume backups-20110930 not removed

root at cel:~
# lvchange -an vg_cel/backups-20110930
  Can't change snapshot logical volume "backups-20110930"

root at cel:~
# lvremove vg_cel/backups-20110930
Do you really want to remove active logical volume backups-20110930? [y/n]: y
  Unable to deactivate open vg_cel-backups--20110930-cow (254:35)
  Failed to resume backups-20110930.
  libdevmapper exiting with 7 device(s) still suspended.


At this point now the entire LVM subsystem is totally frozen. No commands
ever complete. Any LVM-related command hangs and is not SIGKILLable.

root at cel:~
# lvs
^C    

[elsewhere]
root at cel:~
# ps -ef | grep lvs
root     31791 31510  0 15:20 pts/14   00:00:00 lvs
root     32272 32176  0 15:59 pts/17   00:00:00 grep lvs

root at cel:~
# kill -9 31791

root at cel:~
# kill -9 31791

root at cel:~
# kill -9 31791

root at cel:~
# ps -ef | grep lvs
root     31791 31510  0 15:20 pts/14   00:00:00 lvs
root     32274 32176  0 15:59 pts/17   00:00:00 grep lvs


I tried to strace it to see what it was blocked on. Even strace now hangs:


root at cel:~
# strace -p 31791
Process 31791 attached - interrupt to quit
^C
^C


strace is at least killable though:

^Z
[1]+  Stopped                 strace -p 31791

root at cel:~
# kill %1

[1]+  Stopped                 strace -p 31791

root at cel:~
# kill -9 %1

[1]+  Stopped                 strace -p 31791

root at cel:~
# 
[1]+  Killed                  strace -p 31791


In this state the only remedy I have found is a complete reboot of the system.

Other existing LVs do appear to be functioning normally, however, and the
machine generally works fine.

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.0.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages lvm2 depends on:
ii  dmsetup             2:1.02.67-2
ii  initscripts         2.88dsf-13.13
ii  libc6               2.13-24
ii  libdevmapper1.02.1  2:1.02.67-2
ii  libreadline5        5.2-11
ii  libudev0            175-3
ii  lsb-base            3.2-28

lvm2 recommends no packages.

lvm2 suggests no packages.

-- no debconf information