Description of problem:
I attempted to pvmove a clustered linear volume while running gulm, and saw this
panic on three of the four nodes in the cluster while running a 'vgscan'.

Here's the output from the test:

Adding /dev/sdc1 to the volume group on taft-01
Moving data from /dev/sdh1 to /dev/sdc1 on taft-01
    Wiping cache of LVM-capable devices
    Finding volume group "pv_shuffle"
    Executing: /sbin/modprobe dm-cmirror
    Archiving volume group "pv_shuffle" metadata (seqno 4).
    Creating logical volume pvmove0
    Moving 1280 extents of logical volume pv_shuffle/linear
    Updating volume group metadata
    Creating volume group backup "/etc/lvm/backup/pv_shuffle" (seqno 5).
  Error locking on node taft-03: device-mapper: reload ioctl failed: Invalid
argument
  Error locking on node taft-02: device-mapper: reload ioctl failed: Invalid
argument
  Error locking on node taft-04: device-mapper: reload ioctl failed: Invalid
argument
  Error locking on node taft-01: device-mapper: reload ioctl failed: Invalid
argument
  ABORTING: Temporary mirror activation failed.  Run pvmove --abort.


May 27 10:52:38 taft-02 qarshd[16076]: Running cmdline: vgscan
dm-cmirror: Couldn't register clustered_log service.  Reason: -107
dm-cmirror: Unable to connect to cluster infrastructure.
device-mapper: dm-mirror: Error creating mirror dirty log
device-mapper: error adding target to table
Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP:
<ffffffffa02eb78b>{:dm_cmirror:cluster_ctr+411}
PML4 2065c4067 PGD 2069b0067 PMD 0
Oops: 0000 [1] SMP
CPU 2
Modules linked in: dm_cmirror(U) gnbd(U) lock_nolock(U) gfs(U) cman(U)
lock_gulm(U) locd
Pid: 15670, comm: clvmd Not tainted 2.6.9-70.ELsmp
RIP: 0010:[<ffffffffa02eb78b>] <ffffffffa02eb78b>{:dm_cmirror:cluster_ctr+411}
RSP: 0018:00000102065adc28  EFLAGS: 00010286
RAX: fffffffffffffe18 RBX: fffffffffffffe18 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000010213eb6d61 RDI: 00000100dfdc3960
RBP: 0000010213eb6c00 R08: 0000000000000000 R09: 0000000000000000
R10: ffffff0000035000 R11: 0000000000000500 R12: ffffffffa02f3ec0
R13: 0000000000000002 R14: 0000010217967d60 R15: ffffff0000031080
FS:  0000000040a00960(005b) GS:ffffffff8050c580(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 00000000dffae000 CR4: 00000000000006e0
Process clvmd (pid: 15670, threadinfo 00000102065ac000, task 000001020c2dd7f0)
Stack: 0000010000013810 0000000000032000 0000000000000246 0000000000000246
       ffffffffa02f3fa0 ffffff000002a160 0000010217967d60 0000010037e4c610
       0000000000000002 ffffffffa0088271
Call Trace:<ffffffffa0088271>{:dm_mirror:dm_create_dirty_log+212}
       <ffffffffa008a7dc>{:dm_mirror:mirror_ctr+108}
<ffffffffa003f4fa>{:dm_mod:dm_spli
       <ffffffffa003f716>{:dm_mod:dm_table_add_target+328}
       <ffffffffa0041cac>{:dm_mod:table_load+523}
<ffffffffa0041aa1>{:dm_mod:table_load
       <ffffffffa00426a2>{:dm_mod:ctl_ioctl+602} <ffffffff80184796>{sys_newstat+32}
       <ffffffff8018db1d>{sys_ioctl+853} <ffffffff801102b6>{system_call+126}


Code: 48 8b 83 e8 01 00 00 0f 18 08 48 81 fa a0 3e 2f a0 74 68 48
RIP <ffffffffa02eb78b>{:dm_cmirror:cluster_ctr+411} RSP <00000102065adc28>
CR2: 0000000000000000
 <0>Kernel panic - not syncing: Oops



Version-Release number of selected component (if applicable):
2.6.9-70.ELsmp
cmirror-1.0.1-1 Build Date: Tue 30 Jan 2007 05:28:02 PM CST
cmirror-kernel-2.6.9-41.3 Build Date: Mon 19 May 2008 02:00:31 PM CDT