Fix numpy data access by making attribute private (#17890)

`data` attribute of numpy should be marked private as it actually points to the underlying memory and it will be distinct for a cupy array.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #17890

python/cudf/cudf/pandas/_wrappers/numpy.py

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright (c) 2023-2024, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2023-2025, NVIDIA CORPORATION & AFFILIATES.
 # All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
@@ -149,6 +149,7 @@ def ndarray__array_ufunc__(self, ufunc, method, *inputs, **kwargs):
         # Special wrapping to handle scalar values
         "_fsproxy_wrap": classmethod(wrap_ndarray),
         "base": _FastSlowAttribute("base", private=True),
+        "data": _FastSlowAttribute("data", private=True),
     },
 )
 

python/cudf/cudf_pandas_tests/test_cudf_pandas.py

@@ -1927,3 +1927,12 @@ def test_series_dtype_property():
     expected = np.dtype(s)
     actual = np.dtype(xs)
     assert expected == actual
+
+
+def test_numpy_data_access():
+    s = pd.Series([1, 2, 3])
+    xs = xpd.Series([1, 2, 3])
+    expected = s.values.data
+    actual = xs.values.data
+
+    assert type(expected) is type(actual)