Comment 5 for bug 1954635

The major number would suggest that it's a logical volume, but it doesn't seem to correspond to a logical volume, so I'm not sure what it is:
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
loop0 7:0 0 377.4M 1 loop /media/filesystem
loop1 7:1 0 221.8M 1 loop
loop2 7:2 0 82.1M 1 loop /usr/lib/modules
loop3 7:3 0 61.9M 1 loop /snap/core20/1270
loop4 7:4 0 42.2M 1 loop /snap/snapd/14066
loop5 7:5 0 67.2M 1 loop /snap/lxd/21835
loop6 7:6 0 24.3M 1 loop /snap/subiquity/2974
sda 8:0 1 119.5G 0 disk
├─sda1 8:1 1 119.5G 0 part
│ └─ventoy 253:8 0 1.2G 1 dm /cdrom
└─sda2 8:2 1 32M 0 part
sr0 11:0 1 1024M 0 rom
nvme0n1 259:0 0 953.9G 0 disk
├─nvme0n1p1 259:4 0 260M 0 part
├─nvme0n1p2 259:6 0 16M 0 part
├─nvme0n1p3 259:7 0 952.6G 0 part
└─nvme0n1p4 259:8 0 995M 0 part
nvme1n1 259:1 0 953.9G 0 disk
├─nvme1n1p1 259:2 0 512M 0 part
├─nvme1n1p2 259:3 0 1G 0 part
└─nvme1n1p3 259:5 0 952.4G 0 part
  ├─kangaroovg-rootlv 253:0 0 5G 0 lvm
  ├─kangaroovg-usrlv 253:1 0 20G 0 lvm
  ├─kangaroovg-varlv 253:2 0 5G 0 lvm
  ├─kangaroovg-varliblv 253:3 0 7G 0 lvm
  ├─kangaroovg-homelv 253:4 0 100G 0 lvm
  ├─kangaroovg-srvlv 253:5 0 5G 0 lvm
  ├─kangaroovg-usrlocallv 253:6 0 5G 0 lvm
  └─kangaroovg-swaplv 253:7 0 8G 0 lvm
# ls -l /dev/dm*
brw-rw---- 1 root disk 253, 0 Dec 16 03:20 /dev/dm-0
brw-rw---- 1 root disk 253, 1 Dec 16 03:20 /dev/dm-1
brw-rw---- 1 root disk 253, 2 Dec 16 03:20 /dev/dm-2
brw-rw---- 1 root disk 253, 3 Dec 16 03:20 /dev/dm-3
brw-rw---- 1 root disk 253, 4 Dec 16 03:20 /dev/dm-4
brw-rw---- 1 root disk 253, 5 Dec 16 03:20 /dev/dm-5
brw-rw---- 1 root disk 253, 6 Dec 16 03:20 /dev/dm-6
brw-rw---- 1 root disk 253, 7 Dec 16 03:20 /dev/dm-7
brw-rw---- 1 root disk 253, 8 Dec 16 03:20 /dev/dm-8

/dev/dma_heap:
total 0
crw------- 1 root root 249, 0 Dec 16 03:20 system
# lvscan
  ACTIVE '/dev/kangaroovg/rootlv' [5.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/usrlv' [20.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/varlv' [5.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/varliblv' [7.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/homelv' [100.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/srvlv' [5.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/usrlocallv' [5.00 GiB] inherit
  ACTIVE '/dev/kangaroovg/swaplv' [8.00 GiB] inherit
# vgscan
  Found volume group "kangaroovg" using metadata type lvm2
# ls -l /dev/kangaroovg
total 0
lrwxrwxrwx 1 root root 7 Dec 16 08:58 homelv -> ../dm-4
lrwxrwxrwx 1 root root 7 Dec 16 08:58 rootlv -> ../dm-0
lrwxrwxrwx 1 root root 7 Dec 16 08:58 srvlv -> ../dm-5
lrwxrwxrwx 1 root root 7 Dec 16 08:58 swaplv -> ../dm-7
lrwxrwxrwx 1 root root 7 Dec 16 08:58 usrlocallv -> ../dm-6
lrwxrwxrwx 1 root root 7 Dec 16 08:58 usrlv -> ../dm-1
lrwxrwxrwx 1 root root 7 Dec 16 08:58 varliblv -> ../dm-3
lrwxrwxrwx 1 root root 7 Dec 16 08:58 varlv -> ../dm-2
#