Re: [PATCH stable 6.12 0/5] Backport selftest for "bpf: Check skb->transport_header is set in bpf_skb_check_mtu"

["Ricardo B. Marlière" <rbm@suse.com>]

On Tue Feb 24, 2026 at 4:53 AM -03, Harshit Mogalapalli wrote:
> Hi,
>
> On 24/02/26 13:08, Shung-Hsi Yu wrote:
>> This patchset backport the corresponding BPF selftests for commit
>> d946f3c98328 ("bpf: Check skb->transport_header is set in
>> bpf_skb_check_mtu"), which has already been included since 6.12.63.
>> 
>> The BPF selftest added in commit 6cc73f35406c ("selftests/bpf: Test
>> bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set")
>> additionally depends on network namespace support for BPF selftests
>> added by Bastien, otherwise the MTU in root networking namespace will be
>> set to 10, causing other BPF selftests to fail. Credit goes to Ricardo
>> Marlière for figuring out the dependency.
>> 
>
> Note:
> I have recently learnt that ideally we are supposed to run upstream 
> latest kselftests on stable kernels as well. If a feature is not 
> supported the kselftests are meant to be skipped.

That is not true for BPF, from my (limited) experience.

>
> https://lore.kernel.org/all/a45eaddb-9e17-4e82-8a78-a1d1f6e3d735@linuxfoundation.org/
>
> Thanks,
> Harshit
>> Bastien Curutchet (eBPF Foundation) (4):
>>    selftests/bpf: ns_current_pid_tgid: Rename the test function
>>    selftests/bpf: Optionally open a dedicated namespace to run test in it
>>    selftests/bpf: tc_links/tc_opts: Unserialize tests
>>    selftests/bpf: ns_current_pid_tgid: Use test_progs's ns_ feature
>> 
>> Martin KaFai Lau (1):
>>    selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when
>>      transport_header is not set
>> 
>>   .../selftests/bpf/prog_tests/check_mtu.c      | 23 ++++++++-
>>   .../bpf/prog_tests/ns_current_pid_tgid.c      | 49 +++++++------------
>>   .../selftests/bpf/prog_tests/tc_links.c       | 28 +++++------
>>   .../selftests/bpf/prog_tests/tc_opts.c        | 40 +++++++--------
>>   .../selftests/bpf/progs/test_check_mtu.c      | 12 +++++
>>   tools/testing/selftests/bpf/test_progs.c      | 12 +++++
>>   6 files changed, 98 insertions(+), 66 deletions(-)
>>