Hi Mike,

This commit is making my intel box not boot in mm-unstable :>) I bisected it to
this commit.

For what it's worth, we've found the same under Xen too.

There's one concrete bug in the series, failing to cope with the absence
of superpages (fix in
https://lore.kernel.org/xen-devel/6bb03333-74ca-4c2c-85a8-72549b85a5b4@suse.com/ (local)
but not formally posted yet AFAICT).

The rest of the thread then found a crash looking to be the same as
reported here, but you've made better progress narrowing it down than we
have.

~Andrew