If the page is mapped

from mm/vmscan.c

 		if (!page->mapping || page_count(page) > 1) {
 			spin_unlock(&pagecache_lock);
 			UnlockPage(page);
 		page_mapped:
 			if (--max_mapped < 0) {
 				spin_unlock(&pagemap_lru_lock); 

 				shrink_dcache_memory(vm_scan_ratio, gfp_mask);
 				shrink_icache_memory(vm_scan_ratio, gfp_mask);
 				shrink_dqcache_memory(vm_scan_ratio, gfp_mask);
 
 				if (!*failed_swapout)
 					*failed_swapout = !swap_out(classzone);
 				max_mapped = nr_pages * vm_mapped_ratio; 
 
 				spin_lock(&pagemap_lru_lock);
 			}
 			continue;
 			
 		}