On Mon, 15 Jan 2018, Mathieu Desnoyers wrote:

There are two places where core serialization is needed by membarrier:

1) When returning from the membarrier IPI,
2) After scheduler updates curr to a thread with a different mm, before
   going back to user-space, since the curr->mm is used by membarrier to
   check whether it needs to send an IPI to that CPU.

This wants to be split into x86 and core changes. Ideally you make the core
changes before the previous patch and add the empty inline into
linux/processor.h....

Thanks,

	tglx