Where is my /dev/dm-2 2 GB swap partition?

On a brand new Ubuntu 22.04.2 installation, swapon --show shows I have a 2 GB swap partition:

$ swapon --show
NAME      TYPE      SIZE USED PRIO
/dev/dm-2 partition 1.9G   0B   -2

Neither df -h, nor the gparted GUI, however, shows this partition anywhere. Where is it?

Update:

Note that I have a LUKS-encrypted install.

It may be in there. lsblk shows something in my nme0n1 disk:

nvme0n1               259:6    0   1.8T  0 disk  
├─nvme0n1p1           259:7    0   512M  0 part  /boot/efi
├─nvme0n1p2           259:8    0   1.7G  0 part  /boot
└─nvme0n1p3           259:9    0   1.8T  0 part  
  └─nvme0n1p3_crypt   253:0    0   1.8T  0 crypt 
    ├─vgubuntu-root   253:1    0   1.8T  0 lvm   /var/snap/firefox/common/host-hunspell
    │                                            /
    └─vgubuntu-swap_1 253:2    0   1.9G  0 lvm   [SWAP]

Here's what I see in gparted:

Gnome Disks doesn't show it either. Here's a snippet from Disks:

Update: double-clicking in gparted doesn't graphically show the two logical volumes, unfortunately, but it does list them under the "Logical Volumes" section at least! Here I see "root" and "swap_1" logical volumes after double-clicking the LUKS-encrypted partition in gparted:

Double-clicking in Gnome Disks has no effect.

It appears that your swap partition is a LVM partition under nvme0n1p3 which is an encrypted partition that also contains your root file system.

Swap partitions don't have a usable file system like ext4 so tools like df won't show your swap partition.

I don't know why it's not showing in gparted. Is your view showing the divisions underneath nvme0n1p3?

I figured out some more info. which adds additional insight.

Where is my /dev/dm-2 2 GB swap partition?

It's in my LUKS-encrypted partition. Although gparted and Gnome Disks both cannot show the LVM (Logical Volume Manager) volumes within LUKS partitions, blivet-gui, a 3rd partition manager program, can.

Use blivet-gui, instead of gparted or Gnome Disks, to see what is inside of LUKS-encrypted LVM volumes/partitions

Here's what it shows me:

As you can see, my nvme0n1 disk has 3 partitions, with the latter being a 1.82 TiB lvm volume it calls vgubuntu:

If I double-click on it, blivet-gui shows it contains two subvolumes, which it calls type lvmlv. One of my logical volumes is my vgubuntu-root 1.82 TiB root filesystem, and the other is my vgubuntu-swap_1 1.91 GiB swap partition, which is apparently swapon --show is showing as my /dev/dm-2 partition here:

$ swapon --show
NAME      TYPE      SIZE USED PRIO
/dev/dm-2 partition 1.9G   0B   -2

So, although my answer isn't complete either, it at least adds a little more insight. Use the blivet-gui partition editor to see what is inside LUKS-encrypted LVM volumes.

To install blivet-gui

From my answer here: Unix & Linux: How to edit/resize an LVM partition graphically (with a GUI)?:

See blivet-gui's own installation instructions: https://software.opensuse.org/download.html?project=home:vtrefny&package=blivet-gui

Namely, for Ubuntu 22.04 and 20.04:

# For Ubuntu 22.04
echo 'deb http://download.opensuse.org/repositories/home:/vtrefny/xUbuntu_22.04/ /' | sudo tee /etc/apt/sources.list.d/home:vtrefny.list
curl -fsSL https://download.opensuse.org/repositories/home:vtrefny/xUbuntu_22.04/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/home_vtrefny.gpg > /dev/null
sudo apt update
sudo apt install blivet-gui

# For Ubuntu 20.04
echo 'deb http://download.opensuse.org/repositories/home:/vtrefny/xUbuntu_20.04/ /' | sudo tee /etc/apt/sources.list.d/home:vtrefny.list
curl -fsSL https://download.opensuse.org/repositories/home:vtrefny/xUbuntu_20.04/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/home_vtrefny.gpg > /dev/null
sudo apt update
sudo apt install blivet-gui

# etc.