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Message-ID: <db8b80a445a61b437c35c71ec2edb573002656fc.1769157382.git.zhuhui@kylinos.cn>
Date: Fri, 23 Jan 2026 17:01:54 +0800
From: Hui Zhu <hui.zhu@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Shakeel Butt <shakeel.butt@...ux.dev>,
Muchun Song <muchun.song@...ux.dev>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Eduard Zingerman <eddyz87@...il.com>,
Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>,
Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>,
Shuah Khan <shuah@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Miguel Ojeda <ojeda@...nel.org>,
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Kees Cook <kees@...nel.org>,
Tejun Heo <tj@...nel.org>,
Jeff Xu <jeffxu@...omium.org>,
mkoutny@...e.com,
Jan Hendrik Farr <kernel@...rr.cc>,
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Masahiro Yamada <masahiroy@...nel.org>,
davem@...emloft.net,
Jakub Kicinski <kuba@...nel.org>,
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JP Kobryn <inwardvessel@...il.com>,
Willem de Bruijn <willemb@...gle.com>,
Jason Xing <kerneljasonxing@...il.com>,
Paul Chaignon <paul.chaignon@...il.com>,
Anton Protopopov <a.s.protopopov@...il.com>,
Amery Hung <ameryhung@...il.com>,
Chen Ridong <chenridong@...weicloud.com>,
Lance Yang <lance.yang@...ux.dev>,
Jiayuan Chen <jiayuan.chen@...ux.dev>,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
cgroups@...r.kernel.org,
bpf@...r.kernel.org,
netdev@...r.kernel.org,
linux-kselftest@...r.kernel.org
Cc: Hui Zhu <zhuhui@...inos.cn>,
Geliang Tang <geliang@...nel.org>
Subject: [RFC PATCH bpf-next v3 11/12] selftests/bpf: Add test for memcg_bpf_ops hierarchies
From: Hui Zhu <zhuhui@...inos.cn>
Add a new selftest, `test_memcg_ops_hierarchies`, to validate the
behavior of attaching `memcg_bpf_ops` in a nested cgroup hierarchy,
specifically testing the `BPF_F_ALLOW_OVERRIDE` flag.
The test case performs the following steps:
1. Creates a three-level deep cgroup hierarchy: `/cg`, `/cg/cg`, and
`/cg/cg/cg`.
2. Attaches a BPF struct_ops to the top-level cgroup (`/cg`) with the
`BPF_F_ALLOW_OVERRIDE` flag.
3. Successfully attaches a new struct_ops to the middle cgroup
(`/cg/cg`) without the flag, overriding the inherited one.
4. Asserts that attaching another struct_ops to the deepest cgroup
(`/cg/cg/cg`) fails with -EBUSY, because its parent did not specify
`BPF_F_ALLOW_OVERRIDE`.
This test ensures that the attachment logic correctly enforces the
override rules across a cgroup subtree.
Signed-off-by: Geliang Tang <geliang@...nel.org>
Signed-off-by: Hui Zhu <zhuhui@...inos.cn>
---
.../selftests/bpf/prog_tests/memcg_ops.c | 69 +++++++++++++++++++
1 file changed, 69 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/memcg_ops.c b/tools/testing/selftests/bpf/prog_tests/memcg_ops.c
index 9a8d16296f2d..bab9f3094f59 100644
--- a/tools/testing/selftests/bpf/prog_tests/memcg_ops.c
+++ b/tools/testing/selftests/bpf/prog_tests/memcg_ops.c
@@ -535,3 +535,72 @@ void test_memcg_ops_below_min_over_high(void)
close(low_cgroup_fd);
cleanup_cgroup_environment();
}
+
+void test_memcg_ops_hierarchies(void)
+{
+ int ret, first = -1, second = -1, third = -1;
+ struct memcg_ops *skel;
+ struct bpf_map *map;
+ struct bpf_link *link1 = NULL, *link2 = NULL, *link3 = NULL;
+ DECLARE_LIBBPF_OPTS(bpf_struct_ops_opts, opts);
+
+ ret = setup_cgroup_environment();
+ if (!ASSERT_OK(ret, "setup_cgroup_environment"))
+ goto cleanup;
+
+ first = create_and_get_cgroup("/cg");
+ if (!ASSERT_GE(first, 0, "create_and_get_cgroup /cg"))
+ goto cleanup;
+ ret = enable_controllers("/cg", "memory");
+ if (!ASSERT_OK(ret, "enable_controllers"))
+ goto cleanup;
+
+ second = create_and_get_cgroup("/cg/cg");
+ if (!ASSERT_GE(second, 0, "create_and_get_cgroup /cg/cg"))
+ goto cleanup;
+ ret = enable_controllers("/cg/cg", "memory");
+ if (!ASSERT_OK(ret, "enable_controllers"))
+ goto cleanup;
+
+ third = create_and_get_cgroup("/cg/cg/cg");
+ if (!ASSERT_GE(third, 0, "create_and_get_cgroup /cg/cg/cg"))
+ goto cleanup;
+ ret = enable_controllers("/cg/cg/cg", "memory");
+ if (!ASSERT_OK(ret, "enable_controllers"))
+ goto cleanup;
+
+ skel = memcg_ops__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "memcg_ops__open_and_load"))
+ goto cleanup;
+
+ map = bpf_object__find_map_by_name(skel->obj, "low_mcg_ops");
+ if (!ASSERT_OK_PTR(map, "bpf_object__find_map_by_name low_mcg_ops"))
+ goto cleanup;
+
+ opts.relative_fd = first;
+ opts.flags = BPF_F_ALLOW_OVERRIDE;
+ link1 = bpf_map__attach_struct_ops_opts(map, &opts);
+ if (!ASSERT_OK_PTR(link1, "bpf_map__attach_struct_ops_opts"))
+ goto cleanup;
+
+ opts.relative_fd = second;
+ opts.flags = 0;
+ link2 = bpf_map__attach_struct_ops_opts(map, &opts);
+ if (!ASSERT_OK_PTR(link2, "bpf_map__attach_struct_ops_opts"))
+ goto cleanup;
+
+ opts.relative_fd = third;
+ opts.flags = 0;
+ link2 = bpf_map__attach_struct_ops_opts(map, &opts);
+ if (!ASSERT_ERR_PTR(link3, "bpf_map__attach_struct_ops_opts"))
+ goto cleanup;
+
+cleanup:
+ bpf_link__destroy(link1);
+ bpf_link__destroy(link2);
+ memcg_ops__detach(skel);
+ close(first);
+ close(second);
+ close(third);
+ cleanup_cgroup_environment();
+}
--
2.43.0
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