diff --git a/nptl/ChangeLog b/nptl/ChangeLog
index cb9ec53cd1..8dd93732b5 100644
--- a/nptl/ChangeLog
+++ b/nptl/ChangeLog
@@ -1,3 +1,9 @@
+2009-07-27  Ulrich Drepper  <drepper@redhat.com>
+
+	[BZ #10418]
+	* pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Use _rel
+	instead of of _acq variants of cmpxchg.
+
 2009-07-23  Ulrich Drepper  <drepper@redhat.com>
 
 	* sysdeps/x86_64/configure.in: New file.
diff --git a/nptl/pthread_mutex_unlock.c b/nptl/pthread_mutex_unlock.c
index 0028c5583f..fbe8274a55 100644
--- a/nptl/pthread_mutex_unlock.c
+++ b/nptl/pthread_mutex_unlock.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003, 2005-2007, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003, 2005-2008, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -213,7 +213,7 @@ __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
 
       /* Unlock.  */
       if ((mutex->__data.__lock & FUTEX_WAITERS) != 0
-	  || atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock, 0,
+	  || atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, 0,
 						   THREAD_GETMEM (THREAD_SELF,
 								  tid)))
 	{
@@ -263,7 +263,7 @@ __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
 	  oldval = mutex->__data.__lock;
 	  newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK;
 	}
-      while (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
+      while (atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock,
 						   newval, oldval));
 
       if ((oldval & ~PTHREAD_MUTEX_PRIO_CEILING_MASK) > 1)