Verified on qemu-kvm-4.2.0-23.module+el8.2.1+6917+927fbb44.x86_64
libvirt-6.0.0-23.module+el8.2.1+6955+1e1fca42.x86_64
Steps:
➜ ~ dmsetup create --table '0 10240 zero' loop0
➜ ~ virsh destroy pc
Domain pc destroyed
➜ ~ qemu-img create /tmp/raw 100M
Formatting '/tmp/raw', fmt=raw size=104857600
➜ ~ losetup /dev/loop0 /tmp/raw
➜ ~ virsh attach-disk pc /tmp/raw sdb --config
Disk attached successfully
➜ ~ virsh start pc
Domain pc started
➜ ~ virsh destroy pc
Domain pc destroyed
VM started with loop device loop0 while dm loops exists.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2020:3172