Re: tests: CUDA DMA-BUF resources leave exported descriptors open

[Leon Romanovsky <leon@kernel.org>]

On Wed, Nov 04, 2026 at 08:48:09PM +0100, Dezhen Lu wrote:
> Hello,
> 
> At rdma-core master a70151dfec390eb5f7fc5b266f51d601da2a7778,
> the CUDA DMA-BUF test resources obtain an FD from
> cuMemGetHandleForAddressRange but do not close it after registration.
> This affects DmabufCudaRes, MRExDmabufCudaRes,
> MRExDmabufDmaHCudaRes, and Mlx5DmabufCudaRes. It occurs on successful
> registration and on failures or skips after the FD is obtained. The
> integer FD passed to the pyverbs MR constructor is caller-owned.
> 
> The following uses a real process FD and a mocked constructor to
> exercise the first resource method without requiring a CUDA GPU or RDMA
> device. Run it from a checkout with an in-place pyverbs build:
> 
> ```sh
> PYTHONPATH=build/python:tests python3 - <<'PY'
> import errno
> import os
> import sys
> from types import SimpleNamespace
> from unittest.mock import patch
> 
> sys.path.append(sys.path.pop(0))  # Prefer the built pyverbs over the source directory.
> import tests.test_cuda_dmabuf as test
> 
> fd = os.open('/dev/null', os.O_RDONLY)
> res = SimpleNamespace(pd=object(), msg_size=64, mr_access=1,
>                       dmabuf_cuda_init=lambda: fd)
> try:
>     with patch.object(test, 'DmaBufMR', return_value=object()):
>         test.DmabufCudaRes.create_mr(res)
>     try:
>         os.fstat(fd)
>     except OSError as exc:
>         if exc.errno != errno.EBADF:
>             raise
>         print('descriptor closed')
>     else:
>         print('descriptor still open')
> finally:
>     try:
>         os.close(fd)
>     except OSError as exc:
>         if exc.errno != errno.EBADF:
>             raise
> PY
> ```
> 
> Observed: descriptor still open. Expected: descriptor closed after
> registration returns, including on error. A proposed fix closes it in a
> finally block around registration and, for the DMAHandle path, around
> handle creation as well. On Linux the RDMA DMA-BUF registration path
> acquires its own buffer reference.

Please open PR against rdma-core with your fix for both test reports.

Thanks