Re: [PATCH net-next v5 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Fri, Jul 10, 2026 at 07:27:11AM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Unhandled Python exception in selftests when hugepages are disabled or sysctl is read-only.
> --
> 
> --- Patch [3]: [PATCH net-next v5 3/3] selftests/net: devmem.py: add check_rx_large_niov ---
> commit c6680f91b9c04fa78f7d8b9d5f92ce1bee9816c1
> Author: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> selftests/net: devmem.py: add check_rx_large_niov
> 
> This commit adds a new devmem test case for binding a dmabuf with a 16K
> rx-buf-size. It also sweeps various RX payload sizes across the niov boundary
> to exercise the sub-niov, exact-niov, and multi-niov RX paths.
> 
> > diff --git a/tools/testing/selftests/drivers/net/hw/devmem_lib.py b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
> > --- a/tools/testing/selftests/drivers/net/hw/devmem_lib.py
> > +++ b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
> 
> [ ... ]
> 
> > +def run_rx_large_niov(cfg):
> > +    """Run the devmem RX test with a large niov (rx-buf-size > PAGE_SIZE).
> > +
> > +    Sweep payload sizes that straddle the niov boundary: below, equal to,
> > +    and above rx_buf_size, to exercise sub-niov, exact-niov, and multi-niov
> > +    RX paths.
> > +    """
> > +    hp_file = "/proc/sys/vm/nr_hugepages"
> > +    with open(hp_file, 'r+', encoding='utf-8') as f:
> 
> [Severity: Medium]
> Will this crash with an unhandled exception on systems without hugepages
> enabled or when run without write permissions to /proc/sys?
> 
> If the system was compiled without CONFIG_HUGETLB_PAGE=y, opening this file
> will throw a FileNotFoundError, causing the kselftest framework to report a
> test failure rather than gracefully skipping. 
> 
> Could this be wrapped in a try/except block to catch these exceptions and
> raise KsftSkipEx instead?

Do we usually defend against kernels not using the config (in this case,
selftests/drivers/net/hw/config)? Maybe should be a skip? We do already
use this pattern in iou-zcrx.py and nk_qlease.py.

Best,
Bobby