Comment 3 for bug 1902578

To identify the fix, would it be possible for you to do a reverse kernel bisection?

First, find the first -rc kernel works and the last -rc kernel doesn’t work from http://kernel.ubuntu.com/~kernel-ppa/mainline/

Then,
$ sudo apt build-dep linux
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
$ cd linux
$ git bisect start
$ git bisect new $(the working version you found)
$ git bisect old $(the non-working version found)
$ make localmodconfig
$ make -j`nproc` deb-pkg
Install the newly built kernel, then reboot with it.
If it doesn’t work,
$ git bisect old
Otherwise,
$ git bisect new
Repeat to "make -j`nproc` deb-pkg" until you find the commit fixes the issue.