Wow, how did you manage to add comments to the PR without them being
mailed out to be? Perhaps it has something to do with the presence of
multiple names and commas in the Reply-To: field. I seem to recall
gnats having some bugs there.

Anyhow:

| State-Changed-Why:  
| userland programs should not define _KERNEL or face the consequences. 

That's the crux of the question. I don't think that is correct.
It seems to me that userland programs can and should/must define _KERNEL
if they want to see kernel data structures.

Fundamentally, I guess this is a style question. Where do we seek the answer?

I'm going to dupe 10696 into this PR since it was first ;-)

I'm not sure I can agree with you and mrg.

Lex, that will downgrade your PR from critical/high to non-critical/medium.
Can you justify the severity/priority you asserted?

--jhawk