Fix Bug: Initialise the mmap table for the newly created thread rather than the current thread

src/threads/thread.c

@@ -278,7 +278,7 @@ thread_create (const char *name, int priority,
 #endif
 
 #ifdef VM
-  mmap_init ();
+  mmap_init (t);
 #endif
 
   /* Prepare thread for first run by initializing its stack.

src/vm/mmap.c

@@ -6,11 +6,11 @@ static bool mmap_less (const struct hash_elem *a_, const struct hash_elem *b_,
                 void *aux);
 static void mmap_cleanup(struct hash_elem *e, void *aux);
 
-/* Initializes the mmap table for the current thread. Sets the counter to 0. */
+/* Initializes the mmap table for the given thread, setting the mmap counter to
+   0 and initializing the hash table. */
 bool
-mmap_init (void)
+mmap_init (struct thread *t)
 {
-  struct thread *t = thread_current ();
   t->mmap_counter = 0;
   return hash_init (&t->mmap_files, mmap_hash, mmap_less, NULL);
 }

src/vm/mmap.h

@@ -17,7 +17,7 @@ struct mmap_entry {
   struct hash_elem elem; /* An elem for the hash table. */
 };
 
-bool mmap_init (void);
+bool mmap_init (struct thread *t);
 struct mmap_entry *mmap_insert (struct file *file, void *upage);
 void mmap_destroy (void);