Is THREAD_INFO_IN_TASK appropriate for -mm for 4.8?

* Andy Lutomirski [off-list ref] wrote:

Cons: It's a bit odd to merge code that can't be enabled as-is.  OTOH
x86 could plausibly enable it for 4.8 if Ingo is okay with applying
"x86/dumpstack: Pin the target stack in save_stack_trace_tsk()" and
"x86: Move thread_info into task_struct" during the merge window after
the -mm patchbomb lands.

There's quite a few risky stuff piled up already so I'd prefer if we delayed these 
core bits and the enablement to v4.9.

We can carry these core bits in -tip as well, can create a tip:sched/thread_info 
tree for it and such. I'd prefer that because this way we have natural proximity 
between patch application, testing and eventual fixes.

Then we can expose -next to all these changes as a single, bisectable group of 
commits and, should anything overly catastrophic happen, remove it and regroup our 
forces.

This would really be the best approach I think, since I'd like to default-enable 
all this on x86 from the very beginning.

Thanks,

	Ingo