#define pmd_present(pmd) (!pmd_none(pmd))
#define pmd_page_vaddr(pmd) (pmd_val(pmd) & ~PMD_MASKED_BITS)
extern struct page *pmd_page(pmd_t pmd);
+#define pmd_pfn(pmd) (page_to_pfn(pmd_page(pmd)))
static inline void pud_set(pud_t *pudp, unsigned long val)
{