Re: [PATCH v2 00/10] change the implementation of the PageHighMem()

[Christoph Hellwig]

On Fri, May 01, 2020 at 09:15:30PM +0900, Joonsoo Kim wrote:
> I think that PageHighMemZone() is long and complicated enough to have
> a macro.

It is.  But then again it also shouldn't really be used by anything
but MM internals.

> 
> PageHighMemZone(page) = is_highmem_idx(zone_idx(page_zone(page))
> 
> Instead of open-code, how about changing the style of macro like as
> page_from_highmem()? What PageHighMemZone() represent is derivated
> attribute from the page so PageXXX() style may not be appropriate.

Maybe page_is_highmem_zone() with a big kerneldoc comment explaining
the use case?  Bonus points of killing enough users that it can be
in mm/internal.h.