Antoine review comments

python/pyarrow/io.pxi

@@ -1477,7 +1477,8 @@ cdef class Buffer(_Weakrefable):
                 f"pyarrow.MemoryManager, got {type(destination)})"
             )
 
-        c_buffer = GetResultValue(CBuffer.Copy(self.buffer, c_memory_manager))
+        with nogil:
+            c_buffer = GetResultValue(CBuffer.Copy(self.buffer, c_memory_manager))
         return pyarrow_wrap_buffer(c_buffer)
 
     @property

python/pyarrow/tests/test_cuda.py

@@ -127,6 +127,7 @@ def test_copy_from_buffer():
     for dest in [mm2, mm2.device]:
         buf2 = cudabuf.copy(dest)
         assert buf2.device_type == pa.DeviceAllocationType.CUDA
+        assert buf2.copy(pa.default_cpu_memory_manager()).equals(buf)
         cudabuf2 = cuda.CudaBuffer.from_buffer(buf2)
         assert cudabuf2.size == cudabuf.size
         assert not cudabuf2.is_cpu

python/pyarrow/tests/test_io.py

@@ -715,8 +715,8 @@ def test_non_cpu_buffer(pickle_module):
     for dest in [mm, mm.device]:
         buf2 = cuda_buf.copy(dest)
         cuda_buf2 = cuda.CudaBuffer.from_buffer(buf2)
-        cuda_buf2.size == cuda_buf.size
-        cuda_buf2.copy_to_host()[:] == b'testing'
+        assert cuda_buf2.size == cuda_buf.size
+        assert cuda_buf2.copy_to_host()[:] == b'testing'
         assert cuda_buf2.device == mm.device
 
     # Buffers on different devices