From 1a4dc5bc7cb5659a8004d105afeb0571126f8f56 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Wed, 6 Aug 2014 16:06:08 -0700 Subject: [PATCH] mem-hotplug: improve zone_movable_is_highmem logic In original code, zone_movable_is_highmem() assumes ZONE_MOVABLE not highmem if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not set. In online_pages, it extracts pages from the previous zone before ZONE_MOVABLE. Which is logically inconsistent: If HAVE_MEMBLOCK_NODE_MAP is turned off but HIGHMEM is on, zone_movable_is_highmem() makes movable zone not highmem, but online_pages() extracts pages from ZONE_HIGHMEM. This inconsistency doesn't cause real problem currently, because all architectures support online_pages also have HAVE_MEMBLOCK_NODE_MAP. However, fixing it makes code clear, and also helps futher coding. Signed-off-by: Wang Nan Cc: Zhang Zhen Cc: Mel Gorman Cc: Jiang Liu Cc: Li Zefan Cc: Yinghai Lu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6cbd1b6c3d20..559e659288fc 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -872,6 +872,8 @@ static inline int zone_movable_is_highmem(void) { #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) return movable_zone == ZONE_HIGHMEM; +#elif defined(CONFIG_HIGHMEM) + return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM; #else return 0; #endif