[PATCH v2 2/2] mm/mmzone.h: simplify is_highmem_idx()

From: Mike Rapoport
Date: Mon Apr 26 2021 - 10:19:44 EST

From: Mike Rapoport <rppt@xxxxxxxxxxxxx>

There is a lot of historical ifdefery in is_highmem_idx() and its helper
zone_movable_is_highmem() that was required because of two different paths
for nodes and zones initialization that were selected at compile time.

Until commit 3f08a302f533 ("mm: remove CONFIG_HAVE_MEMBLOCK_NODE_MAP
option") the movable_zone variable was only available for configurations
that had CONFIG_HAVE_MEMBLOCK_NODE_MAP enabled so the test in
zone_movable_is_highmem() used that variable only for such configurations.
For other configurations the test checked if the index of ZONE_MOVABLE was
greater by 1 than the index of ZONE_HIGMEM and then movable zone was
considered a highmem zone. Needless to say, ZONE_MOVABLE - 1 equals
ZONE_HIGHMEM by definition when CONFIG_HIGHMEM=y.

Commit 3f08a302f533 ("mm: remove CONFIG_HAVE_MEMBLOCK_NODE_MAP option")
made movable_zone variable always available. Since this variable is set to
ZONE_HIGHMEM if CONFIG_HIGHMEM is enabled and highmem zone is populated, it
is enough to check whether

zone_idx == ZONE_MOVABLE && movable_zone == ZONE_HIGMEM

to test if zone index points to a highmem zone.

Remove zone_movable_is_highmem() that is not used anywhere except
is_highmem_idx() and use the test above in is_highmem_idx() instead.

Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
include/linux/mmzone.h | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0d53eba1c383..c2bfefd34b59 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -982,22 +982,11 @@ static inline void zone_set_nid(struct zone *zone, int nid) {}

extern int movable_zone;

-static inline int zone_movable_is_highmem(void)
- return movable_zone == ZONE_HIGHMEM;
- return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM;
static inline int is_highmem_idx(enum zone_type idx)
return (idx == ZONE_HIGHMEM ||
- (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
+ (idx == ZONE_MOVABLE && movable_zone == ZONE_HIGHMEM));
return 0;