fix bmm enforce equal batch (#27694)

python/paddle/fluid/tests/unittests/test_bmm_op.py

@@ -79,8 +79,10 @@ class TestBmmAPIError(unittest.TestCase):
         y_data = np.arange(16, dtype='float32').reshape((2, 4, 2))
         y_data_wrong1 = np.arange(16, dtype='float32').reshape((2, 2, 4))
         y_data_wrong2 = np.arange(16, dtype='float32').reshape((2, 2, 2, 2))
+        y_data_wrong3 = np.arange(24, dtype='float32').reshape((3, 4, 2))
         self.assertRaises(ValueError, paddle.bmm, x_data, y_data_wrong1)
         self.assertRaises(ValueError, paddle.bmm, x_data, y_data_wrong2)
+        self.assertRaises(ValueError, paddle.bmm, x_data, y_data_wrong3)
 
 
 if __name__ == "__main__":

python/paddle/tensor/linalg.py

@@ -848,6 +848,10 @@ def bmm(x, y, name=None):
         raise ValueError(
             "x's width must be equal with y's height. But received x's shape: {}, y's shape: {}".
             format(x_shape, y_shape))
+    if x_shape[0] != y_shape[0]:
+        raise ValueError(
+            "x's batch (shape[0]) must be equal with y's batch (shape[0]). But received x's shape: {}, y's shape: {}".
+            format(x_shape, y_shape))
     helper = LayerHelper('bmm', **locals())
     if in_dygraph_mode():
         return core.ops.bmm(x, y)