Re: [PATCH v2 bpf-next] selftests/bpf: Fix cgroup_xattr/read_cgroupfs_xattr

[Ihor Solodrai <ihor.solodrai@linux.dev>]

On 6/27/25 2:38 PM, Alexei Starovoitov wrote:
> On Fri, Jun 27, 2025 at 2:36 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
>>
>> On 6/27/25 2:34 PM, Alexei Starovoitov wrote:
>>> On Fri, Jun 27, 2025 at 2:19 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
>>>>
>>>> On 6/27/25 12:12 PM, Song Liu wrote:
>>>>> cgroup_xattr/read_cgroupfs_xattr has two issues:
>>>>>
>>>>> 1. cgroup_xattr/read_cgroupfs_xattr messes up lo without creating a netns
>>>>>       first. This causes issue with other tests.
>>>>>
>>>>>       Fix this by using a different hook (lsm.s/file_open) and not messing
>>>>>       with lo.
>>>>>
>>>>> 2. cgroup_xattr/read_cgroupfs_xattr sets up cgroups without proper
>>>>>       mount namespaces.
>>>>>
>>>>>       Fix this by using the existing cgroup helpers. A new helper
>>>>>       set_cgroup_xattr() is added to set xattr on cgroup files.
>>>>>
>>>>> Fixes: f4fba2d6d282 ("selftests/bpf: Add tests for bpf_cgroup_read_xattr")
>>>>> Reported-by: Alexei Starovoitov <ast@kernel.org>
>>>>> Closes: https://lore.kernel.org/bpf/CAADnVQ+iqMi2HEj_iH7hsx+XJAsqaMWqSDe4tzcGAnehFWA9Sw@mail.gmail.com/
>>>>> Signed-off-by: Song Liu <song@kernel.org>
>>>>>
>>>>> ---
>>>>> Changes v1 => v2:
>>>>> 1. Add the second fix above.
>>>>>
>>>>> v1: https://lore.kernel.org/bpf/20250627165831.2979022-1-song@kernel.org/
>>>>> ---
>>>>>     tools/testing/selftests/bpf/cgroup_helpers.c  |  21 ++++
>>>>>     tools/testing/selftests/bpf/cgroup_helpers.h  |   4 +
>>>>>     .../selftests/bpf/prog_tests/cgroup_xattr.c   | 117 ++++--------------
>>>>>     .../selftests/bpf/progs/read_cgroupfs_xattr.c |   4 +-
>>>>>     4 files changed, 49 insertions(+), 97 deletions(-)
>>>>
>>>> Hi Song.
>>>>
>>>> I tried this patch on BPF CI, and it appears it fixes the hanging
>>>> failure we've been seeing today on bpf-next and netdev.
>>>> I am going to add it to ci/diffs.
>>>
>>> Applied to bpf-next already.
>>
>> CI patches apply to all base branches. My understanding is, it's needed
>> at least for netdev too.
> 
> How is that possible?
> 
> The offending commit is only in /master and in /for-next branches,
> while /for-next is there for linux-next only.

I am not sure.

I compared CI logs between bpf-next and netdev runs that both were
cancelled due to 100min job timeout, and they are very similar.

netdev: 
https://github.com/kernel-patches/bpf/actions/runs/15932863319/job/44946276955
bpf-next: 
https://github.com/kernel-patches/bpf/actions/runs/15934258609/job/44950981852

So the root cause is likely the same.

And most recent netdev (with this patch applied) is green:
https://github.com/kernel-patches/bpf/actions/runs/15936292169

CC Jakub