Re: [PATCH] mm/Kconfig: additional help text for HMM_MIRROR option

[Christoph Hellwig]

On Mon, Jul 22, 2019 at 08:58:04AM -0300, Jason Gunthorpe wrote:
> No one has given me a satisfactory answer about the restriction
> either.
> 
> The only thing this kconfig controls that could possibly be arch
> specific is the page walking code in hmm_range_snapshot and
> related. 
> 
> Maybe there is/was some arch entanglement there?

The page walking code is supposed to be platform independent.
I did push a branch to the buildbot a few days ago to catch issues,
and the only one found so far is an abuse of pte_index() that can be
trivially fixed.  The other thing I noticed is that the use of some
of the p??_none/protnone/present checks seems inconsistent, but I did
not have time to audit that yet.