[Bug-fix] fix bug of Tensor.item() when CUDAPinnedPlace (#52322)

paddle/fluid/pybind/eager_method.cc

@@ -980,7 +980,14 @@ static PyObject* tensor__getitem_from_offset(TensorObject* self,
                                              PyObject* args,
                                              PyObject* kwargs) {
   EAGER_TRY
-  auto ptr = static_cast<phi::DenseTensor*>(self->tensor.impl().get());
+  phi::DenseTensor* ptr = nullptr;
+  if (self->tensor.is_selected_rows()) {
+    auto* selected_rows =
+        static_cast<phi::SelectedRows*>(self->tensor.impl().get());
+    ptr = static_cast<phi::DenseTensor*>(selected_rows->mutable_value());
+  } else {
+    ptr = static_cast<phi::DenseTensor*>(self->tensor.impl().get());
+  }
   PADDLE_ENFORCE_NOT_NULL(ptr,
                           platform::errors::InvalidArgument(
                               "%s is not a DenseTensor.", self->tensor.name()));

paddle/fluid/pybind/tensor_py.h

@@ -276,7 +276,8 @@ T TensorGetElement(const phi::DenseTensor &self, size_t offset) {
                         "The offset exceeds the size of tensor."));
 
   T b = static_cast<T>(0);
-  if (platform::is_cpu_place(self.place())) {
+  if (platform::is_cpu_place(self.place()) ||
+      platform::is_cuda_pinned_place(self.place())) {
     b = self.data<T>()[offset];
   } else if (platform::is_xpu_place(self.place())) {
 #ifdef PADDLE_WITH_XPU

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

@@ -168,7 +168,7 @@ class TestVarBase(unittest.TestCase):
                 self.assertEqual(x_array.dtype, x.numpy().dtype)
                 np.testing.assert_array_equal(x_array, x.numpy())
 
-                x = paddle.to_tensor(1.0)
+                x = paddle.to_tensor(1.0, place=place)
                 self.assertEqual(x.item(), 1.0)
                 self.assertTrue(isinstance(x.item(), float))