Hi,

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