> diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c b/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c
> --- a/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c
> +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_iter_memcg.c

[ ... ]

> @@ -143,6 +151,8 @@ static void test_kmem(struct bpf_link *link, struct memcg_query *memcg_query)
>  	if (!ASSERT_OK(read_stats(link), "read stats"))
>  		goto cleanup;
>
> +	ASSERT_NEQ(memcg_query->memcg_kmem, (unsigned long)-1,
> +		  "bpf_mem_cgroup_vm_events MEMCG_KMEM");

Should this assertion string say "bpf_mem_cgroup_page_state MEMCG_KMEM"
instead?  The BPF program in progs/cgroup_iter_memcg.c populates
memcg_kmem using bpf_mem_cgroup_page_state(), not
bpf_mem_cgroup_vm_events():

    idx = bpf_core_enum_value(enum memcg_stat_item, MEMCG_KMEM);
    ...
    memcg_query.memcg_kmem = bpf_mem_cgroup_page_state(memcg, idx);

> @@ -170,6 +180,8 @@ 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_page_state PGFAULT");

Similarly, should this say "bpf_mem_cgroup_vm_events PGFAULT"?  The BPF
program retrieves pgfault using bpf_mem_cgroup_vm_events():

    idx = bpf_core_enum_value(enum vm_event_item, PGFAULT);
    ...
    memcg_query.pgfault = bpf_mem_cgroup_vm_events(memcg, idx);

It looks like the two assertion description strings for test_kmem and
test_pgfault were swapped.


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21978734425

AI-authorship-score: low
AI-authorship-explanation: The commit describes a specific back-porting scenario, and the copy-paste error in swapped assertion strings is characteristic of human authorship.
issues-found: 2
issue-severity-score: low
issue-severity-explanation: Two assertion description strings are swapped between test_kmem and test_pgfault, producing misleading diagnostics on test failure but not affecting test correctness or system stability.