diff --git a/exec.c b/exec.c
index e968d2f..6be6af1 100644
--- a/exec.c
+++ b/exec.c
@@ -20,7 +20,6 @@ exec(char *path, char **argv)
 
   begin_op();
 
-  cprintf("exec %s\n", path);
   if((ip = namei(path)) == 0){
     end_op();
     return -1;
@@ -100,7 +99,6 @@ exec(char *path, char **argv)
   proc->tf->esp = sp;
   switchuvm(proc);
   freevm(oldpgdir);
-  cprintf("exec succeeded\n");
   return 0;
 
  bad:
diff --git a/runoff.list b/runoff.list
index 73d39f7..3db7072 100644
--- a/runoff.list
+++ b/runoff.list
@@ -35,12 +35,14 @@ sysproc.c
 
 # file system
 buf.h
+sleeplock.h
 fcntl.h
 stat.h
 fs.h
 file.h
 ide.c
 bio.c
+sleeplock.c
 log.c
 fs.c
 file.c
diff --git a/spinlock.c b/spinlock.c
index 2f0e873..942d93d 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -61,7 +61,7 @@ release(struct spinlock *lk)
 
   // Release the lock, equivalent to lk->locked = 0.
   // This code can't use a C assignment, since it might
-  // not be atomic.
+  // not be atomic. A real OS would use C atomics here.
   asm volatile("movl $0, %0" : "+m" (lk->locked) : );
 
   popcli();