Re: [PATCH rdma-rc] RDMA/mlx5: Fix DevX umem page size truncation for pages >= 4G

[sashiko-bot@kernel.org]

> From: Dezhen Lu <dezhen.lu@student.uni-tuebingen.de>
> 
> devx_umem_find_best_pgsize() computes the page size in an unsigned long
> but returns it as unsigned int, and devx_umem_reg_cmd_alloc() stores it
> in an unsigned int. When the DMA mapping of the umem is contiguous and
> aligned to 4 GiB or more, and the umem length is a multiple of that
> size, ib_umem_find_best_pgoff() selects a page size >= 2^32. Since the
> value is a power of two, the truncation turns it into 0 and the
> registration fails with -EINVAL.
> 
> The umem log_page_size field is 5 bits wide on top of
> MLX5_ADAPTER_PAGE_SHIFT, so the command can encode these page sizes.
> 
> Seen on two GH200 nodes (ConnectX-7, firmware 32.38.3056 and
> 32.43.1014) with a dma-buf exported from cudaMalloc memory: registering
> [ ... ]
> GH200 nodes described above.
> 
> Fixes: 7610ab57de56 ("RDMA/mlx5: Allow larger pages in DevX umem")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dezhen Lu <dezhen.lu@student.uni-tuebingen.de>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261103142709.66179-1-dezhen.lu@student.uni-tuebingen.de?part=1