[PATCH bpf-next v5 0/2] Fix test_cgroup_iter_memcg issues found during back-porting

[Hui Zhu <hui.zhu@linux.dev>]

From: Hui Zhu <zhuhui@kylinos.cn>

While back-porting "mm: bpf kfuncs to access memcg data", I
encountered issues with test_cgroup_iter_memcg, specifically
in test_kmem.
The test_cgroup_iter_memcg test would falsely pass when
bpf_mem_cgroup_page_state() failed due to incompatible enum
values across kernel versions. Additionally, test_kmem would
fail on systems with cgroup.memory=nokmem enabled.

These patches are my fixes for the problems I encountered.

Changelog:
v5:
According to the comments of Emil Tsalapatis and JP Kobryn, dropped
"selftests/bpf: Check bpf_mem_cgroup_page_state return value".
v4:
Fixed wrong git commit log in "bpf: Use bpf_core_enum_value for stats in
cgroup_iter_memcg".
v3:
According to the comments of JP Kobryn, remove kmem subtest from
cgroup_iter_memcg and fix assertion string in test_pgfault.
v2:
According to the comments of JP Kobryn, added bpf_core_enum_value()
usage in the BPF program to handle cross-kernel enum value differences
at load-time instead of compile-time.
Dropped the mm/memcontrol.c patch.
Modified test_kmem handling: instead of skipping when nokmem is set,
verify that kmem value is zero as expected.
According to the comments of bot, fixed assertion message: changed
"bpf_mem_cgroup_page_state" to "bpf_mem_cgroup_vm_events" for PGFAULT
check.

Hui Zhu (2):
  selftests/bpf: Remove kmem subtest from cgroup_iter_memcg
  bpf: Use bpf_core_enum_value for stats in cgroup_iter_memcg

 .../testing/selftests/bpf/cgroup_iter_memcg.h |  2 --
 .../bpf/prog_tests/cgroup_iter_memcg.c        | 28 -------------------
 .../selftests/bpf/progs/cgroup_iter_memcg.c   | 18 ++++++++----
 3 files changed, 12 insertions(+), 36 deletions(-)

-- 
2.43.0