Comment 3 for bug 1467906

Indeed! After a little more investigating, I commented out two lines in my fstab. I've been manually mounting the encrypted swap partition since then.

ericp@pucky:~$ sudo blkid
[sudo] password for ericp:
/dev/mapper/sda5_crypt: UUID="uDe29v-IL2u-mHU0-GBjD-H9ji-DCNc-P29L5g" TYPE="LVM2_member"
/dev/sda1: UUID="b4203a7f-9fc4-42c6-bd9d-f5796fff0f80" TYPE="ext2" PARTUUID="5cc8b93f-01"
/dev/sda5: UUID="447ea4a7-b12a-4b3b-b7ec-bef21e754103" TYPE="crypto_LUKS" PARTUUID="5cc8b93f-05"
/dev/mapper/ubuntu--vg-root: UUID="3864ee8c-65e6-4608-89ef-4cb0fec13d6c" TYPE="ext4"
/dev/mapper/ubuntu--vg-swap_1: UUID="709c35fb-a74b-4c98-b341-246e0e65621d" TYPE="swap"
/dev/mapper/cryptswap1: UUID="7564b3fa-a22b-42ee-948a-be7104a5dbb1" TYPE="swap"

ericp@pucky:~$ ls -lR /dev/disk/by-uuid
/dev/disk/by-uuid:
total 0
lrwxrwxrwx 1 root root 10 Jun 30 08:09 3864ee8c-65e6-4608-89ef-4cb0fec13d6c -> ../../dm-1
lrwxrwxrwx 1 root root 10 Jun 30 08:09 447ea4a7-b12a-4b3b-b7ec-bef21e754103 -> ../../sda5
lrwxrwxrwx 1 root root 10 Jun 30 08:09 709c35fb-a74b-4c98-b341-246e0e65621d -> ../../dm-2
lrwxrwxrwx 1 root root 10 Jun 30 08:09 7564b3fa-a22b-42ee-948a-be7104a5dbb1 -> ../../dm-3
lrwxrwxrwx 1 root root 10 Jun 30 08:09 b4203a7f-9fc4-42c6-bd9d-f5796fff0f80 -> ../../sda1

fstab - I'm including the lines I commented out:
/dev/mapper/ubuntu--vg-root / ext4 errors=remount-ro 0 1
UUID=b4203a7f-9fc4-42c6-bd9d-f5796fff0f80 /boot ext2 defaults 0 2
# ericp this is not the encrypted swap? /dev/mapper/ubuntu--vg-swap_1 none swap sw 0 0
# ericp this doesn't exist /dev/mapper/cryptswap1 none swap sw 0 0

ericp@pucky:~$ cat /etc/crypttab
sda5_crypt UUID=447ea4a7-b12a-4b3b-b7ec-bef21e754103 none luks,discard
cryptswap1 UUID=709c35fb-a74b-4c98-b341-246e0e65621d /dev/urandom swap,offset=1024,cipher=aes-xts-plain64

There it is. Interestingly enough, I've been using /dev/mapper to manually mount dm-3 as my crypt swap, and it's been working fine.

ericp@pucky:~$ ll /dev/mapper
total 0
drwxr-xr-x 2 root root 140 Jun 30 08:09 ./
drwxr-xr-x 22 root root 4680 Jun 30 08:30 ../
crw------- 1 root root 10, 236 Jun 30 08:09 control
lrwxrwxrwx 1 root root 7 Jun 30 08:09 cryptswap1 -> ../dm-3
lrwxrwxrwx 1 root root 7 Jun 30 08:09 sda5_crypt -> ../dm-0
lrwxrwxrwx 1 root root 7 Jun 30 08:09 ubuntu--vg-root -> ../dm-1
lrwxrwxrwx 1 root root 7 Jun 30 08:09 ubuntu--vg-swap_1 -> ../dm-2