# define pfn_to_page(pfn) (mem_map + (pfn))
#elif defined(CONFIG_DISCONTIGMEM)
extern struct page *vmem_map;
+extern unsigned long min_low_pfn;
extern unsigned long max_low_pfn;
-# define pfn_valid(pfn) (((pfn) < max_low_pfn) && ia64_pfn_valid(pfn))
+# define pfn_valid(pfn) (((pfn) >= min_low_pfn) && ((pfn) < max_low_pfn) && ia64_pfn_valid(pfn))
# define page_to_pfn(page) ((unsigned long) (page - vmem_map))
# define pfn_to_page(pfn) (vmem_map + (pfn))
#endif