Comment 34 for bug 1320402

Roger, many thanks for finding that. At first it looked like it wouldn't work for me, but it turns out that both kernel >= 4.4.2 AND the script fixes in comment #13 are necessary.

I have also tested and found that both fixes in #13 are still required:

- /etc/init.d/mdadm: The mdmon pid is put into sendsigs.d at stop, but that's not enough -
   it has to happen already at start. MatthewHawn commented on that already in #13.

- /etc/init.d/umountroot: The "mdadm --wait-clean --scan" kludge there is also still
   required. I note there's a script /etc/init.d/mdadm-waitidle that looks like it's
   supposed to do this, but it doesn't actually work. Probably some kind of sequencing
   problem, but I haven't dug into that.

So, the recipe to work around this bug in wily and xenial ought to be:

1. Download and apply MatthewHawns patch in #13
    (https://launchpadlibrarian.net/191488884/mdadm.patch).

2. Go to e.g. http://kernel.ubuntu.com/~kernel-ppa/mainline/ and pick a kernel >= 4.4.2
    (I've tested with 4.4.2 and the latest 4.4 atm, 4.4.17). Download the .debs for the
    architecture you need and install them using dpkg -i. See
    https://wiki.ubuntu.com/Kernel/MainlineBuilds for more detailed instructions.