Cannot delete lvm thin volume

[Nikolay Borisov <kernel@kyup.com>]

Hello I have the following thin volume, which I'd like to delete:

lvdisplay -v /dev/coregroup/c13537_2k
    Using logical volume(s) on command line.
  --- Logical volume ---
  LV Path                /dev/coregroup/c13537_2k
  LV Name                c13537_2k
  VG Name                coregroup
  LV UUID                LBPr0i-uac8-i3Co-5B3M-A6Bv-q8iv-kSRLRr
  LV Write Access        read/write
  LV Creation host, time xxxxx.net, 2015-10-14 02:02:45 -0500
  LV Pool name           corepool
  LV Status              available
  # open                 1
  LV Size                1.80 TiB
  Mapped size            42.11%
  Current LE             471808
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:6

dmsetup info coregroup-c13537_2k
Name:              coregroup-c13537_2k
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        1
Event number:      1
Major, minor:      252, 6
Number of targets: 1
UUID: LVM-M8PwSxzGcsZQTtdgzfixsr08ZAlNpAbALBPr0iuac8i3Co5B3MA6Bvq8ivkSRLRr

dmsetup status
coregroup-c13537_2k: 0 3865051136 thin 1627684864 3865042943

The version of the software is:
lvremove --version
  LVM version:     2.02.118(2)-RHEL6 (2015-09-08)
  Library version: 1.02.95-RHEL6 (2015-09-08)
  Driver version:  4.26.0

And the kernel is 3.12.47.

When I run 'lvremove -f /dev/coregroup/c13537_2k' I get the following
error: Logical volume coregroup/c13537_2k contains a filesystem in use.
I also get the same error when I try to deactivate the volume.

fuser doesn't report anything and the volume is not mounted anywhere. I
have also acquired an ftrace trace from executing lvremove but there are
multiple invocation of the dm_ioctl function and I'm not sure which one
is the relevant. So if you tell me what information in particular you
need I'd post it here.

Regards,
Nikolay