On Tue, Sep 9, 2025 at 9:21 AM Nimrod Oren <noren@xxxxxxxxxx> wrote: > > On 05/09/2025 1:16, Amery Hung wrote: > > On Thu, Aug 28, 2025 at 6:39 AM Nimrod Oren <noren@xxxxxxxxxx> wrote: > >> I got a crash when testing this series with the xdp_dummy program from > >> tools/testing/selftests/net/lib/. Need to make sure we're not breaking > >> compatibility for programs that keep the linear part empty. > > > > ping.py test ran successfully for me. Is this what you tried but > > crashed the kernel? > > Yes, that's odd. Is it possible that the native multibuf case was > skipped over because of an older iproute2/libbpf version? > > If it's helpful, I used iproute2-6.16.0 built with libbpf 1.7.0 support. > I am able to reproduce the crash by loading multibuf prog directly with: > `ip link set dev eth0 mtu 9000 xdp obj > tools/testing/selftests/net/lib/xdp_dummy.bpf.o sec xdp.frags` I can reproduce it with v2. Will fix it in v3. The bug is that sinfo->flags is also cleared in build_skb(), so later xdp_buff_has_frags() will always return false and no data was ever pulled into the linear part.
