From: "JP Kobryn (Meta)" <jp.kobryn@linux.dev>
To: Hui Zhu <hui.zhu@linux.dev>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Hui Zhu <zhuhui@kylinos.cn>
Subject: Re: [PATCH bpf-next v4 3/3] selftests/bpf: Check bpf_mem_cgroup_page_state return value
Date: Mon, 2 Mar 2026 10:27:09 -0800 [thread overview]
Message-ID: <ea103a43-7192-4c00-b837-c85ebba6f9b1@linux.dev> (raw)
In-Reply-To: <c6b0c44062f614ddeaae26b17e3a4f1876a9f9ed.1772270591.git.zhuhui@kylinos.cn>
On 2/28/26 1:25 AM, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@kylinos.cn>
>
> When back-porting test_progs to different kernel versions, I encountered
> an issue where the test_cgroup_iter_memcg test would falsely pass even
> when bpf_mem_cgroup_page_state() failed.
>
> This patch adds explicit checks to ensure bpf_mem_cgroup_page_state()
> doesn't return -1 before validating the actual statistics values.
>
> Signed-off-by: Hui Zhu <zhuhui@kylinos.cn>
> ---
> .../selftests/bpf/prog_tests/cgroup_iter_memcg.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c b/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c
> index 88fc3e83d2b7..9eadfbd3fdb9 100644
> --- a/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c
> +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c
> @@ -53,6 +53,8 @@ static void test_anon(struct bpf_link *link, struct memcg_query *memcg_query)
> if (!ASSERT_OK(read_stats(link), "read stats"))
> goto cleanup;
>
> + ASSERT_NEQ(memcg_query->nr_anon_mapped, (unsigned long)-1,
> + "bpf_mem_cgroup_page_state NR_ANON_MAPPED");
> ASSERT_GT(memcg_query->nr_anon_mapped, 0, "final anon mapped val");
>
> cleanup:
> @@ -88,6 +90,10 @@ static void test_file(struct bpf_link *link, struct memcg_query *memcg_query)
> if (!ASSERT_OK(read_stats(link), "read stats"))
> goto cleanup_map;
>
> + ASSERT_NEQ(memcg_query->nr_file_pages, (unsigned long)-1,
> + "bpf_mem_cgroup_page_state NR_FILE_PAGES");
> + ASSERT_NEQ(memcg_query->nr_file_mapped, (unsigned long)-1,
> + "bpf_mem_cgroup_page_state NR_FILE_MAPPED");
> ASSERT_GT(memcg_query->nr_file_pages, 0, "final file value");
> ASSERT_GT(memcg_query->nr_file_mapped, 0, "final file mapped value");
>
> @@ -119,6 +125,8 @@ static void test_shmem(struct bpf_link *link, struct memcg_query *memcg_query)
> if (!ASSERT_OK(read_stats(link), "read stats"))
> goto cleanup;
>
> + ASSERT_NEQ(memcg_query->nr_shmem, (unsigned long)-1,
> + "bpf_mem_cgroup_page_state NR_SHMEM");
> ASSERT_GT(memcg_query->nr_shmem, 0, "final shmem value");
>
> cleanup:
> @@ -144,6 +152,8 @@ static void test_pgfault(struct bpf_link *link, struct memcg_query *memcg_query)
> if (!ASSERT_OK(read_stats(link), "read stats"))
> goto cleanup;
>
> + ASSERT_NEQ(memcg_query->pgfault, (unsigned long)-1,
> + "bpf_mem_cgroup_vm_events PGFAULT");
> ASSERT_GT(memcg_query->pgfault, 0, "final pgfault val");
>
> cleanup:
Emil mentioned in the v3 thread that we don't need these checks [0]. I
agree. Now that you're using the bpf co-re enum helpers, the stat
indexes won't become an issue in a cross-kernel secenario. This patch
can be dropped.
[0]
https://lore.kernel.org/bpf/DGQXZVBSVEUP.35P5G9QOL9EAT@etsalapatis.com/T/#m7cb6edf90ed4daaeda38b746363317405f198f20
prev parent reply other threads:[~2026-03-02 18:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-28 9:25 [PATCH bpf-next v4 0/3] Fix test_cgroup_iter_memcg issues found during back-porting Hui Zhu
2026-02-28 9:25 ` [PATCH bpf-next v4 1/3] selftests/bpf: Remove kmem subtest from cgroup_iter_memcg Hui Zhu
2026-03-02 18:08 ` JP Kobryn (Meta)
2026-02-28 9:25 ` [PATCH bpf-next v4 2/3] bpf: Use bpf_core_enum_value for stats in cgroup_iter_memcg Hui Zhu
2026-03-02 18:10 ` JP Kobryn (Meta)
2026-02-28 9:25 ` [PATCH bpf-next v4 3/3] selftests/bpf: Check bpf_mem_cgroup_page_state return value Hui Zhu
2026-03-02 18:27 ` JP Kobryn (Meta) [this message]
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