Comment 11 for bug 1850540

There is no plan to reapply the kernel side of these fixes ahead of 18.04.4. Introducing the mdadm side of that in 18.04.4 therefore would cause a regression in functionality:

ubuntu@ip-172-30-0-208:~$ sudo mdadm --create /dev/md0 --run
--metadata=default --level=0 --raid-devices=2 /dev/xvdb /dev/xvdc
mdadm: /dev/xvdb appears to be part of a raid array:
       level=raid0 devices=2 ctime=Wed Dec 11 22:10:59 2019
mdadm: /dev/xvdc appears to be part of a raid array:
       level=raid0 devices=2 ctime=Wed Dec 11 22:10:59 2019
mdadm: ADD_NEW_DISK for /dev/xvdb failed: Invalid argument
mdadm: Possibly your kernel doesn't support RAID0 layouts.
mdadm: Either upgrade, or use --layout=dangerous

Of course, at install time, upgrading the kernel isn't an option. So let's hold this SRU until after the point release.