mm/sparse-vmemmap: rename HVO order macros

The macros VMEMMAP_TAIL_MIN_ORDER and NR_VMEMMAP_TAILS describe the order
range where HVO can be applied, but their names tie that range to the
tail-page cache implementation.

Rename them with a VMEMMAP_OPTIMIZATION prefix and use the new names in
the HVO paths.  This makes the code describe the optimization requirements
rather than the tail-page cache implementation detail.

No functional change intended.

Link: https://lore.kernel.org/20260910063256.64386-3-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>

4 files changed, 14 insertions, 13 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0a2428714108..5fb9b37819d5 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -107,13 +107,14 @@
 	 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 struct pages covered by the retained vmemmap pages with HVO enabled. */
+#define VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES	(PAGE_SIZE / sizeof(struct page))
+#define VMEMMAP_OPTIMIZATION_MIN_ORDER		(ilog2(VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) + 1)
+
+#define __VMEMMAP_OPTIMIZATION_NR_ORDERS	\
+	(MAX_FOLIO_ORDER - VMEMMAP_OPTIMIZATION_MIN_ORDER + 1)
+#define VMEMMAP_OPTIMIZATION_NR_ORDERS		\
+	(__VMEMMAP_OPTIMIZATION_NR_ORDERS > 0 ? __VMEMMAP_OPTIMIZATION_NR_ORDERS : 0)
 
 enum migratetype {
 	MIGRATE_UNMOVABLE,
@@ -1158,7 +1159,7 @@ 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[VMEMMAP_OPTIMIZATION_NR_ORDERS];
 #endif
 } ____cacheline_internodealigned_in_smp;
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e645d2d25bb6..b2aa988979e9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3357,7 +3357,7 @@ 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 < VMEMMAP_OPTIMIZATION_NR_ORDERS; i++) {
 			struct page *tail, *p;
 			unsigned int order;
 
@@ -3365,7 +3365,7 @@ void __init hugetlb_bootmem_struct_page_init(void)
 			if (!tail)
 				continue;
 
-			order = i + VMEMMAP_TAIL_MIN_ORDER;
+			order = i + VMEMMAP_OPTIMIZATION_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 917db0984143..ae8fdaa42118 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -494,7 +494,7 @@ 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 - VMEMMAP_OPTIMIZATION_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 5a2469fb1838..aa6a4a2fae98 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -329,12 +329,12 @@ 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 < VMEMMAP_OPTIMIZATION_MIN_ORDER))
 		return NULL;
 	if (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))
 		return NULL;
 
-	idx = order - VMEMMAP_TAIL_MIN_ORDER;
+	idx = order - VMEMMAP_OPTIMIZATION_MIN_ORDER;
 	tail = zone->vmemmap_tails[idx];
 	if (tail)
 		return tail;