[RFC PATCH 23/39] mm: hugetlb: Expose HugeTLB functions for promoting/demoting pages

[Ackerley Tng]

These functions will be used by guest_memfd to split/reconstruct
HugeTLB pages.

Co-developed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Co-developed-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
Signed-off-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
---
 include/linux/hugetlb.h | 15 +++++++++++++++
 mm/hugetlb.c            |  8 ++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 7ba4ed9e0001..ac9d4ada52bd 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -298,6 +298,21 @@ static inline void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
+bool prep_compound_gigantic_folio(struct folio *folio, unsigned int order);
+void destroy_compound_gigantic_folio(struct folio *folio, unsigned int order);
+#else
+bool prep_compound_gigantic_folio(struct folio *folio, unsigned int order)
+{
+	return false;
+}
+
+static inline void destroy_compound_gigantic_folio(struct folio *folio,
+						   unsigned int order)
+{
+}
+#endif
+
 #else /* !CONFIG_HUGETLB_PAGE */
 
 static inline void hugetlb_dup_vma_private(struct vm_area_struct *vma)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 372d8294fb2f..8f2b7b411b60 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1533,8 +1533,7 @@ static void destroy_compound_hugetlb_folio_for_demote(struct folio *folio,
 }
 
 #ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static void destroy_compound_gigantic_folio(struct folio *folio,
-					unsigned int order)
+void destroy_compound_gigantic_folio(struct folio *folio, unsigned int order)
 {
 	__destroy_compound_gigantic_folio(folio, order, false);
 }
@@ -1609,8 +1608,6 @@ static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
 }
 static inline void free_gigantic_folio(struct folio *folio,
 						unsigned int order) { }
-static inline void destroy_compound_gigantic_folio(struct folio *folio,
-						unsigned int order) { }
 #endif
 
 /*
@@ -2120,8 +2117,7 @@ static bool __prep_compound_gigantic_folio(struct folio *folio,
 	return false;
 }
 
-static bool prep_compound_gigantic_folio(struct folio *folio,
-							unsigned int order)
+bool prep_compound_gigantic_folio(struct folio *folio, unsigned int order)
 {
 	return __prep_compound_gigantic_folio(folio, order, false);
 }
-- 
2.46.0.598.g6f2099f65c-goog