set_bit(PG_highmem, &page->flags);
void map_high_region(unsigned long start_pfn, unsigned long end_pfn){	unsigned long tmp;#ifdef CONFIG_DEBUG_HIGHMEM	printk("mapping high region %08lx - %08lx\n", start_pfn, end_pfn);#endif	for (tmp = start_pfn; tmp < end_pfn; tmp++) {		struct page *page = pfn_to_page(tmp);		ClearPageReserved(page);		set_bit(PG_highmem, &page->flags);		set_page_count(page, 1);		__free_page(page);		totalhigh_pages++;	}}