[PATCH hmm 8/8] mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling

[Christoph Hellwig]

On Mon, Mar 16, 2020 at 10:04:58AM -0300, Jason Gunthorpe wrote:
> > Ok.  I had some cleanups like this based of older trees, but if you are
> > active in this area I think I'll let you handle it.
> 
> You once said you wanted to loose the weird pfn flags scheme, so
> before putting hmm_range_fault in ODP I planned to do that.
> 
> If you have your series someplace send me a URL and I'll look on it

I have a local branch I just started hacking on, but it is rather broken
based on various discussions we had.  But for a basic one I'd suggest
something like:

 - kill HMM_PFN_SPECIAL as it serves no purpose
 - split the ->pfns array into an input flags (optional) and an output
   pfn (mandtory) one, using new flags for the input side
 - replace the output flags/values indirection with a bunch of values
   encoded in the high bits of a u64, with the rest used for the pfn