--- a/src/impl/vm_impl_private.cbc	Fri Jan 24 14:54:09 2020 +0900
+++ b/src/impl/vm_impl_private.cbc	Fri Jan 24 15:22:44 2020 +0900
@@ -187,7 +187,7 @@
         if (mem == 0) {
             cprintf("allocuvm out of memory\n");
             deallocuvm(pgdir, newsz, oldsz);
-            goto next(ret, ...);
+            goto next(0, ...);
         }
 
         memset(mem, 0, PTE_SZ);
@@ -198,3 +198,18 @@
     ret = newsz; 
     goto next(ret, ...);
 }
+
+__code clearpteu_check_ptevm_impl(struct vm_impl* vm_impl, pde_t* pgdir, char* uva, __code next(int ret, ...)) {
+    pte_t *pte;
+
+    pte = walkpgdir(pgdir, uva, 0);
+    if (pte == 0) {
+        // panic("clearpteu");
+        // goto panic;
+    }
+
+    // in ARM, we change the AP field (ap & 0x3) << 4)
+    *pte = (*pte & ~(0x03 << 4)) | AP_KO << 4;
+
+    goto next(ret, ...);
+}