#define pfn_to_page(pfn) (mem_map + (pfn))
#define page_to_pfn(page) ((unsigned long)((page) - mem_map))
#define pfn_valid(pfn) ((pfn) < max_mapnr)
#define pfn_to_page(pfn) (mem_map + (pfn))
#define page_to_pfn(page) ((unsigned long)((page) - mem_map))
#define pfn_valid(pfn) ((pfn) < max_mapnr)