2020년 5월 1일 (금) 오후 9:30, Christoph Hellwig <hch@xxxxxxxxxxxxx>님이 작성: > > On Wed, Apr 29, 2020 at 12:26:40PM +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 #3 for this patch. > > > > Acked-by: Roman Gushchin <guro@xxxxxx> > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > --- > > mm/memory_hotplug.c | 2 +- > > mm/page_alloc.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > index 555137b..891c214 100644 > > --- a/mm/memory_hotplug.c > > +++ b/mm/memory_hotplug.c > > @@ -593,7 +593,7 @@ void generic_online_page(struct page *page, unsigned int order) > > __free_pages_core(page, order); > > totalram_pages_add(1UL << order); > > #ifdef CONFIG_HIGHMEM > > - if (PageHighMem(page)) > > + if (PageHighMemZone(page)) > > totalhigh_pages_add(1UL << order); > > #endif > > } > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index fc5919e..7fe5115 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -7444,7 +7444,7 @@ void adjust_managed_page_count(struct page *page, long count) > > atomic_long_add(count, &page_zone(page)->managed_pages); > > totalram_pages_add(count); > > #ifdef CONFIG_HIGHMEM > > - if (PageHighMem(page)) > > + if (PageHighMemZone(page)) > > totalhigh_pages_add(count); > > #endif > > This function already uses the page_zone structure above, I think > life would be easier of you compare against that, as that makes > the code more obvious. If I can kill all the PageHighMemZone() macro, I will use page_zone() above. However, if it's not possible, I will leave it as it is. It would be simpler than your suggestion. Thanks.
