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

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

On 6/27/25 2:56 PM, Ihor Solodrai wrote:
> 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
> 
> 

Apparently offending patches were merged by Christian Brauner:

https://github.com/linux-netdev/testing-bpf-ci/commit/13b0cce9e294f8ddf228b9db3e01d76ac29872f2