clear np->mem after freeing

0992df4b · rsc · 21a88dd0 · 0992df4b
--- a/proc.c
+++ b/proc.c
@@ -107,6 +107,7 @@ copyproc(struct proc* p)
  np->kstack = kalloc(KSTACKSIZE);
  if(np->kstack == 0){
    kfree(np->mem, np->sz);
+    np->mem = 0;
    np->state = UNUSED;
    return 0;
  }