fix: do not leak when inserting the same page twice, just update

src/vm/page.c

@@ -95,6 +95,16 @@ page_insert_file (struct file *file, off_t ofs, void *upage,
                   uint32_t read_bytes, uint32_t zero_bytes, bool writable,
                   enum page_type type)
 {
+  /* If page exists, just update it. */
+  struct page_entry *existing = page_get (upage);
+  if (existing != NULL)
+    {
+      ASSERT (existing->read_bytes == read_bytes);
+      ASSERT (existing->zero_bytes == zero_bytes);
+      existing->writable = existing->writable || writable;
+      return existing;
+    }
+
   struct page_entry *page = malloc(sizeof (struct page_entry));
   if (page == NULL)
     return NULL;