Re: [PATCH 02/10] drm/ttm: separate PageHighMem() and PageHighMemZone() use case

[Joonsoo Kim]

2020ë 4ì 20ì (ì) ìí 5:42, Christian KÃnig <christian.koenig@xxxxxxx>ëì ìì:
>
> Am 20.04.20 um 09:59 schrieb js1304@xxxxxxxxx:
> > From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> >
> > Until now, PageHighMem() is used for two different cases. One is to check
> > if there is a direct mapping for this page or not. The other is to check
> > the zone of this page, that is, weather it is the highmem type zone or not.
> >
> > Now, we have separate functions, PageHighMem() and PageHighMemZone() for
> > each cases. Use appropriate one.
> >
> > Note that there are some rules to determine the proper macro.
> >
> > 1. If PageHighMem() is called for checking if the direct mapping exists
> > or not, use PageHighMem().
> > 2. If PageHighMem() is used to predict the previous gfp_flags for
> > this page, use PageHighMemZone(). The zone of the page is related to
> > the gfp_flags.
> > 3. If purpose of calling PageHighMem() is to count highmem page and
> > to interact with the system by using this count, use PageHighMemZone().
> > This counter is usually used to calculate the available memory for an
> > kernel allocation and pages on the highmem zone cannot be available
> > for an kernel allocation.
> > 4. Otherwise, use PageHighMemZone(). It's safe since it's implementation
> > is just copy of the previous PageHighMem() implementation and won't
> > be changed.
> >
> > I apply the rule #4 for this patch.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> Reviewed-by: Christian KÃnig <christian.koenig@xxxxxxx> for the TTM
> changes, but I can't judge if the general approach makes sense or not.

Thanks for review!
General approach needs to get an agreement from more developers.

Thanks.