Re: [PATCH v2 01/17] mm/gup: Fixup p*_access_permitted()

[Linus Torvalds]

On Fri, Dec 15, 2017 at 4:29 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> So do you want to do a straight revert of these that went in for 4.15:

I think that's the right thing to do, but would want to verify that
there are no *other* issues than just the attempt at PKRU.

The commit message does talk about PAGE_USER, and as mentioned I do
think that's a good thing to check, I just don't think it should be
done this way,

Was there something else going behind these commits? Because if not,
let's revert and then perhaps later introduce a more targeted thing?

Also, aren't the protection keys encoded in the vma?

Because *if* we want to check protection keys, I think we should do
that at the vma layer, partly exactly because the exact implementation
of protection keys is so architecture-specific, and partly because I
don't think it makes sense to check them for every page anyway.

               Linus