Is THREAD_INFO_IN_TASK appropriate for -mm for 4.8?

On Mon, Jul 18, 2016 at 04:47:39PM -0700, Andy Lutomirski wrote:

Hi all-

There are four core patches needed for the THREAD_INFO_IN_TASK thing,
and they apply cleanly to -mm now.  The x86 patch to flip the feature
on does not apply cleanly anywhere because it depends on changes in
-tip *and* in -mm.  I'd like to get all of this as well as the rest of
the vmap-stacks stuff in by 4.9, but I'm wondering if it might make
sense to get the core THREAD_INFO_IN_TASK stuff into -mm for 4.8
instead.

Pros:
 - It reduces the amount of core code that -tip will have to carry until 4.9.
 - It may benefit other architectures.  Christian Borntraeger
expressed an interest in enabling the feature for s390, but it'll be
awkward for him until the core bit landed.  Similarly, arm64 seems to
be interested.

This would probably be useful for arm64.

There's still a reasonable amount to figure out (e.g. [1,2]), so from my
PoV this is a nice-to-have, but there's no pressure.

Thanks,
Mark.

[1] https://lkml.org/lkml/2016/7/11/193
[2] https://lkml.org/lkml/2016/7/11/483