[linux-lvm] "Unknown feature in status" message when running lvs/lvdisplay against cached LVs

[Gang He]

Hi Guys,

I uses lvm2-2.02.180, I got an error message when running lvs/lvdisplay against cached LVs.
e.g. 
linux-v5ay:~ # lvs
  Unknown feature in status: 8 1324/8192 128 341/654272 129 151 225 1644 0 341 0 3 metadata2 writethrough no_discard_passdown 2 migration_threshold 2048 smq 0 rw -
  LV   VG     Attr       LSize  Pool       Origin       Data%  Meta%  Move Log Cpy%Sync Convert
  home system -wi-ao---- 17.99g
  root system Cwi-aoC--- 20.00g [lvc_root] [root_corig] 0.05   16.16           0.00
  swap system -wi-ao----  2.00g

The bug can be reproduced stably with the below steps.
Have a (virtual) machine with 2 disk drives
Install os with LVM as root volume
Then, add the second disk after os is installed.
# pvcreate /dev/sdb
# vgextend system /dev/sdb
# lvcreate --type cache-pool -l 100%FREE -n lvc_root system /dev/sdb
# lvconvert --type cache --cachepool system/lvc_root system/root
then run `lvs` or `lvdisplay` command to trigger the issue


Thanks
Gang