[PATCH 03/17] mm/sparse-vmemmap: introduce folio-oriented vmemmap optimization macros

[Muchun Song]

Introduce macros for those folio-oriented properties and use them to
replace the tail-based names in the HVO paths. This makes the code read
in terms of folio semantics instead of an implementation detail and
better matches other folio-based users such as DAX.

No functional change intended.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 include/linux/mmzone.h | 18 ++++++++++--------
 mm/hugetlb.c           |  4 ++--
 mm/hugetlb_vmemmap.c   |  2 +-
 mm/sparse-vmemmap.c    |  4 ++--
 4 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index bacd89572c5c..ea884245f499 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -107,13 +107,15 @@
 	 is_power_of_2(sizeof(struct page)) ? \
 	 MAX_FOLIO_NR_PAGES * sizeof(struct page) : 0)
 
-/*
- * vmemmap optimization (like HVO) is only possible for page orders that fill
- * two or more pages with struct pages.
- */
-#define VMEMMAP_TAIL_MIN_ORDER (ilog2(2 * PAGE_SIZE / sizeof(struct page)))
-#define __NR_VMEMMAP_TAILS (MAX_FOLIO_ORDER - VMEMMAP_TAIL_MIN_ORDER + 1)
-#define NR_VMEMMAP_TAILS (__NR_VMEMMAP_TAILS > 0 ? __NR_VMEMMAP_TAILS : 0)
+/* The number of vmemmap pages required by a vmemmap-optimized folio. */
+#define OPTIMIZED_FOLIO_VMEMMAP_PAGES		1
+#define OPTIMIZED_FOLIO_VMEMMAP_SIZE		(OPTIMIZED_FOLIO_VMEMMAP_PAGES * PAGE_SIZE)
+#define OPTIMIZED_FOLIO_VMEMMAP_NR_STRUCT_PAGES	(OPTIMIZED_FOLIO_VMEMMAP_SIZE / sizeof(struct page))
+#define OPTIMIZABLE_FOLIO_MIN_ORDER		(ilog2(OPTIMIZED_FOLIO_VMEMMAP_NR_STRUCT_PAGES) + 1)
+
+#define __NR_OPTIMIZABLE_FOLIO_ORDERS		(MAX_FOLIO_ORDER - OPTIMIZABLE_FOLIO_MIN_ORDER + 1)
+#define NR_OPTIMIZABLE_FOLIO_ORDERS		\
+	(__NR_OPTIMIZABLE_FOLIO_ORDERS > 0 ? __NR_OPTIMIZABLE_FOLIO_ORDERS : 0)
 
 enum migratetype {
 	MIGRATE_UNMOVABLE,
@@ -1147,7 +1149,7 @@ struct zone {
 	atomic_long_t		vm_stat[NR_VM_ZONE_STAT_ITEMS];
 	atomic_long_t		vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
-	struct page *vmemmap_tails[NR_VMEMMAP_TAILS];
+	struct page *vmemmap_tails[NR_OPTIMIZABLE_FOLIO_ORDERS];
 #endif
 } ____cacheline_internodealigned_in_smp;
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e1bb81631d5e..1ef6edaa3993 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3301,7 +3301,7 @@ void __init hugetlb_bootmem_struct_page_init(void)
 	struct zone *zone;
 
 	for_each_zone(zone) {
-		for (int i = 0; i < NR_VMEMMAP_TAILS; i++) {
+		for (int i = 0; i < NR_OPTIMIZABLE_FOLIO_ORDERS; i++) {
 			struct page *tail, *p;
 			unsigned int order;
 
@@ -3309,7 +3309,7 @@ void __init hugetlb_bootmem_struct_page_init(void)
 			if (!tail)
 				continue;
 
-			order = i + VMEMMAP_TAIL_MIN_ORDER;
+			order = i + OPTIMIZABLE_FOLIO_MIN_ORDER;
 			p = page_to_virt(tail);
 			/*
 			 * prep_and_add_bootmem_folios() can access pageblock
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index eefd6b5f9706..196312a6fafb 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -495,7 +495,7 @@ static bool vmemmap_should_optimize_folio(const struct hstate *h, struct folio *
 
 static struct page *vmemmap_get_tail(unsigned int order, struct zone *zone)
 {
-	const unsigned int idx = order - VMEMMAP_TAIL_MIN_ORDER;
+	const unsigned int idx = order - OPTIMIZABLE_FOLIO_MIN_ORDER;
 	struct page *tail, *p;
 	int node = zone_to_nid(zone);
 
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 785d2b042fe3..1d72283e179b 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -327,12 +327,12 @@ static __meminit struct page *vmemmap_get_tail(unsigned int order, struct zone *
 	unsigned int idx;
 	int node = zone_to_nid(zone);
 
-	if (WARN_ON_ONCE(order < VMEMMAP_TAIL_MIN_ORDER))
+	if (WARN_ON_ONCE(order < OPTIMIZABLE_FOLIO_MIN_ORDER))
 		return NULL;
 	if (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))
 		return NULL;
 
-	idx = order - VMEMMAP_TAIL_MIN_ORDER;
+	idx = order - OPTIMIZABLE_FOLIO_MIN_ORDER;
 	tail = zone->vmemmap_tails[idx];
 	if (tail)
 		return tail;
-- 
2.54.0