mm/thp: rename pmd_to_page() as pmd_pgtable_page()

Current pmd_to_page(), which derives the page table page containing the
pmd address has a very misleading name.  The problem being, it sounds
similar to pmd_page() which derives page embedded in a given pmd entry
either for next level page or a mapped huge page.  Rename it as
pmd_pgtable_page() instead.

Link: https://lkml.kernel.org/r/20221124131641.1523772-1-anshuman.khandual@arm.comSigned-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm.h

@@ -2510,7 +2510,7 @@ static inline void pgtable_pte_page_dtor(struct page *page)
 
 #if USE_SPLIT_PMD_PTLOCKS
 
-static struct page *pmd_to_page(pmd_t *pmd)
+static struct page *pmd_pgtable_page(pmd_t *pmd)
 {
 	unsigned long mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
 	return virt_to_page((void *)((unsigned long) pmd & mask));
@@ -2518,7 +2518,7 @@ static struct page *pmd_to_page(pmd_t *pmd)
 
 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
-	return ptlock_ptr(pmd_to_page(pmd));
+	return ptlock_ptr(pmd_pgtable_page(pmd));
 }
 
 static inline bool pmd_ptlock_init(struct page *page)
@@ -2537,7 +2537,7 @@ static inline void pmd_ptlock_free(struct page *page)
 	ptlock_free(page);
 }
 
-#define pmd_huge_pte(mm, pmd) (pmd_to_page(pmd)->pmd_huge_pte)
+#define pmd_huge_pte(mm, pmd) (pmd_pgtable_page(pmd)->pmd_huge_pte)
 
 #else