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. Previous patches introduce PageHighMemZone() macro and separates both cases strictly. So, now, PageHighMem() is used just for checking if there is a direct mapping for this page or not. In the following patchset, ZONE_MOVABLE which could be considered as the highmem type zone in some configuration could have both types of pages, direct mapped pages and unmapped pages. So, current implementation of PageHighMem() that checks the zone rather than checks the page in order to check if a direct mapping exists will be invalid. This patch prepares that case by implementing PageHighMem() with the max_low_pfn. Acked-by: Roman Gushchin <guro@xxxxxx> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> --- include/linux/page-flags.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index fca0cce..7ac5fc8 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -375,6 +375,8 @@ PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND) #ifdef CONFIG_HIGHMEM +extern unsigned long max_low_pfn; + /* * Must use a macro here due to header dependency issues. page_zone() is not * available at this point. @@ -383,7 +385,7 @@ PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) * in order to predict previous gfp_flags or to count something for system * memory management. */ -#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) +#define PageHighMem(__p) (page_to_pfn(__p) >= max_low_pfn) #define PageHighMemZone(__p) is_highmem_idx(page_zonenum(__p)) #else PAGEFLAG_FALSE(HighMem) -- 2.7.4
