Index: Lib/test/test_slice.py
===================================================================
--- Lib/test/test_slice.py	(revision 46671)
+++ Lib/test/test_slice.py	(working copy)
@@ -92,8 +92,29 @@
 
         self.assertRaises(OverflowError, slice(None).indices, 1L<<100)
 
-def test_main():
+    def test_cycles_leak(self):
+        # This test shows results only in a debug build when
+        # run as a script or with the -R option to regrtest.py.
+        class C(object):
+            pass
+
+        for i in range(10):
+            c = C()
+            s = slice(c)
+            c.slice = s
+
+def test_main(verbose=None):
     test_support.run_unittest(SliceTest)
 
+    # verify reference counting
+    if verbose and hasattr(sys, "gettotalrefcount"):
+        import gc
+        counts = [None] * 5
+        for i in xrange(len(counts)):
+            test_support.run_unittest(SliceTest)
+            gc.collect()
+            counts[i] = sys.gettotalrefcount()
+        print counts
+
 if __name__ == "__main__":
-    test_main()
+    test_main(verbose=True)
Index: Objects/sliceobject.c
===================================================================
--- Objects/sliceobject.c	(revision 46671)
+++ Objects/sliceobject.c	(working copy)
@@ -60,7 +60,7 @@
 PyObject *
 PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
 {
-	PySliceObject *obj = PyObject_New(PySliceObject, &PySlice_Type);
+	PySliceObject *obj = PyObject_GC_New(PySliceObject, &PySlice_Type);
 
 	if (obj == NULL)
 		return NULL;
@@ -76,6 +76,7 @@
 	obj->start = start;
 	obj->stop = stop;
 
+	_PyObject_GC_TRACK(obj);
 	return (PyObject *) obj;
 }
 
@@ -217,10 +218,11 @@
 static void
 slice_dealloc(PySliceObject *r)
 {
-	Py_DECREF(r->step);
-	Py_DECREF(r->start);
-	Py_DECREF(r->stop);
-	PyObject_Del(r);
+	_PyObject_GC_UNTRACK(r);
+	Py_CLEAR(r->step);
+	Py_CLEAR(r->start);
+	Py_CLEAR(r->stop);
+	PyObject_GC_Del(r);
 }
 
 static PyObject *
@@ -240,6 +242,15 @@
 	return s;
 }
 
+static int
+slice_traverse(PySliceObject *r, visitproc visit, void *arg)
+{
+	Py_VISIT(r->step);
+	Py_VISIT(r->start);
+	Py_VISIT(r->stop);
+	return 0;
+}
+
 static PyMemberDef slice_members[] = {
 	{"start", T_OBJECT, offsetof(PySliceObject, start), READONLY},
 	{"stop", T_OBJECT, offsetof(PySliceObject, stop), READONLY},
@@ -329,9 +340,9 @@
 	PyObject_GenericGetAttr,		/* tp_getattro */
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
-	Py_TPFLAGS_DEFAULT,			/* tp_flags */
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
 	slice_doc,				/* tp_doc */
-	0,					/* tp_traverse */
+	(traverseproc)slice_traverse,		/* tp_traverse */
 	0,					/* tp_clear */
 	0,					/* tp_richcompare */
 	0,					/* tp_weaklistoffset */