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

[Joonsoo Kim]

2020ë 5ì 1ì (ê) ìí 7:55, Christoph Hellwig <hch@xxxxxxxxxxxxx>ëì ìì:
>
> On Fri, May 01, 2020 at 07:52:35PM +0900, Joonsoo Kim wrote:
> > > - New code will pop up which gets it wrong and nobody will notice for
> > >   a long time.
> >
> > Hmm... I think that it's not that hard to decide correct macro. If we rename
> > PageHighMem() with PageDirectMapped(), they, PageDirectMapped() and
> > PageHighMemZone(), are self-explanation macro. There would be no
> > confusion to use.
>
> What confuses me is why we even need PageHighMemZone - mostly code
> should not care about particular zones.  Maybe just open coding
> PageHighMemZone makes more sense - it is a little more cumersome, but
> at least it makes it explicit what we check for.  I already sent you
> an incremental diff for one obvious place, but maybe we need to look
> through the remaining ones if we can kill them or open code them in an
> obvious way.

I think that PageHighMemZone() is long and complicated enough to have
a macro.

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.

Thanks.