[ resending without broken headers ]
this is a backport of commit 7aa54be297655 ("locking/qspinlock, x86:
Provide liveness guarantee") for the v4.9 stable tree.
For the v4.4 tree the ARCH_USE_QUEUED_SPINLOCKS option got disabled on
x86.
For v4.9 it has been decided to do a minimal backport of the final fix
(including all its dependencies).
With this backport I can't reproduce the issue in the latest v4.9-RT
tree. I was able to boot (and use) an arm64 box with these patches so it
is not broken in an abvious way.
Sebastian
