2020년 4월 22일 (수) 오후 4:44, Christoph Hellwig <hch@xxxxxxxxxxxxx>님이 작성: > > On Mon, Apr 20, 2020 at 04:59:35PM +0900, js1304@xxxxxxxxx wrote: > > 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 #2 for this patch. > > > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > --- > > include/linux/migrate.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > > index 3e546cb..9a57766 100644 > > --- a/include/linux/migrate.h > > +++ b/include/linux/migrate.h > > @@ -47,7 +47,7 @@ static inline struct page *new_page_nodemask(struct page *page, > > order = HPAGE_PMD_ORDER; > > } > > > > - if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE)) > > + if (PageHighMemZone(page) || zone_idx(page_zone(page)) == ZONE_MOVABLE) > > gfp_mask |= __GFP_HIGHMEM; > > I think this would be much cleaner if you open coded PageHighMemZone > here. > > E.g. > > int zone = page_zone(page); > > if (is_highmem_idx(zone) || zone_idx(zone) == ZONE_MOVABLE) Okay. I will use open code here to make two condition checks similar form. Thanks.
