Re: Udpated sys_membarrier() speedup patch, FYI

[Peter Zijlstra]

On Mon, Jul 31, 2017 at 09:03:09AM +0300, Avi Kivity wrote:
> I remembered that current->mm does not change when switching to a kernel
> task, but my Kernlish is very rusty, or maybe it has changed.

kernel threads do indeed preserve the mm of the old userspace task, but
we track that in ->active_mm. Their ->mm will be NULL.