mm: add a warning in map_page if a page is already mapped

src/mm/page_tables.c

@@ -70,6 +70,11 @@ void map_page(void *physaddr, void *virtualaddr, unsigned int flags) {
     // Here you need to check whether the PT entry is present.
     // When it is, then there is already a mapping present. What do you do now?
 
+    if(pt[ptindex] & 0x1)
+    {
+        printf("this page 0x%X is already mapped\n", virtualaddr);
+    }
+
     pt[ptindex] = ((unsigned long)physaddr) | (flags & 0xFFF); // Present
 
     // Now you need to flush the entry in the TLB