Re: [PATCH bpf-next v14 8/8] selftests/bpf: Add tests to verify map create failure log

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Hardcoded value of 0xFF (255) for invalid NUMA node and invalid token FD may cause spurious test failures on certain systems.
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commit b99a7cb4d2c7cfcc2878066c51d6ca1706eaa83a
Author: Leon Hwang <leon.hwang@linux.dev>

selftests/bpf: Add tests to verify map create failure log

Add tests to verify that the kernel reports the expected error messages
and correct log_true_size when map creation fails.

> diff --git a/tools/testing/selftests/bpf/prog_tests/map_init.c b/tools/testing/selftests/bpf/prog_tests/map_init.c
> index 14a31109dd0e0..5c61c8e373065 100644
> --- a/tools/testing/selftests/bpf/prog_tests/map_init.c
> +++ b/tools/testing/selftests/bpf/prog_tests/map_init.c
[ ... ]
> +static void test_invalid_numa_node(void)
> +{
> +	const char *msg = "Invalid numa_node.\n";
> +	LIBBPF_OPTS(bpf_map_create_opts, opts,
> +		    .map_flags = BPF_F_NUMA_NODE,
> +		    .numa_node = 0xFF,

Would this test be flaky on a massive system? Using 0xFF (255) for the
NUMA node could accidentally match an online node on systems with large NUMA
topologies (e.g., up to 1024 nodes).

Would it be safer to use ~0U or -1 to represent a guaranteed invalid node?

> +	);
> +
> +	test_map_create_array(&opts, msg);
> +}
[ ... ]
> +static void test_invalid_token_fd(void)
> +{
> +	const char *msg = "Invalid map_token_fd.\n";
> +	LIBBPF_OPTS(bpf_map_create_opts, opts,
> +		    .map_flags = BPF_F_TOKEN_FD,
> +		    .token_fd = 0xFF,

Could the use of 0xFF (255) as a file descriptor lead to spurious test failures?

While an open FD 255 is unlikely to be a BPF token, using -1 or ~0U is the
standard way to provide an invalid FD, which completely eliminates the risk of
accidentally hitting an open file descriptor.

> +	);
> +
> +	test_map_create_array(&opts, msg);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260512153157.28382-1-leon.hwang@linux.dev?part=8