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

From: Christoph Hellwig
Date: Fri May 01 2020 - 08:34:33 EST


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.