On Mon, 2017-11-13 at 10:26 +1100, Benjamin Herrenschmidt wrote:

On Sat, 2017-11-11 at 10:03 -0500, Mathieu Desnoyers wrote:

quoted

x86 has a missing core serializing instruction in migration scenarios.

Given that x86-32 can return to user-space with sysexit, and x86-64
through sysretq and sysretl, which are not core serializing, the
following user-space self-modifiying code (JIT) scenario can occur:

Is this about load/store consistency ? In this case, don't you also
have problems with get/put_user and not just going to userspace ?

Ah forget it, I saw Linus earlier messages.

Cheers,
Ben.