Re: [PATCH bpf] selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep

[Daniel Borkmann]

On 7/8/24 6:42 PM, KP Singh wrote:
> On Mon, Jul 8, 2024 at 6:09 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
> > On 7/8/24 5:35 PM, Puranjay Mohan wrote:
> > > Daniel Borkmann <daniel@xxxxxxxxxxxxx> writes:
> > > > On 7/8/24 5:26 PM, KP Singh wrote:
> > > > > On Mon, Jul 8, 2024 at 5:00 PM Puranjay Mohan <puranjay@xxxxxxxxxx> wrote:
> > > > > > Daniel Borkmann <daniel@xxxxxxxxxxxxx> writes:
> > > > > > > On 7/5/24 4:50 PM, Puranjay Mohan wrote:
> > > > > > > > fexit_sleep test runs successfully now on the CI so remove it from the
> > > > > > > > deny list.
> > > > > > >
> > > > > > > Do you happen to know which commit fixed it? If yes, might be nice to have it
> > > > > > > documented in the commit message.
> > > > > >
> > > > > > Actually, I never saw this test failing on my local setup and yesterday
> > > > > > I tried running it on the CI where it passed as well. So, I assumed that
> > > > > > this would be fixed by some commit. I am not sure which exact commit
> > > > > > might have fixed this.
> > > > > >
> > > > > > Manu, Martin
> > > > > >
> > > > > > When this was added to the deny list was this failing every time and did
> > > > > > you have some reproducer for this. If there is a reproducer, I can try
> > > > > > fixing it but when ran normally this test never fails for me.
> > > > >
> > > > > I think this never worked until
> > > > > https://lore.kernel.org/lkml/20230405180250.2046566-1-revest@xxxxxxxxxxxx/
> > > > > was merged, FTrace direct calls was blocking tracing programs on ARM,
> > > > > since then it has always worked.
> > > >
> > > > Awesome, thanks! I'll add this to the commit desc then when applying.
> > >
> > > The commit that added this to the deny list said:
> > > 31f4f810d533 ("selftests/bpf: Add fexit_sleep to DENYLIST.aarch64")
> > >
> > > ```
> > > It is reported that the fexit_sleep never returns in aarch64.
> > > The remaining tests cannot start.
> > > ```
>
> It may also have something to do with sleepable programs. But I think
> it's generally in the category of "BPF tracing was catching up with
> ARM", it has now.

Hm, the latest run actually hangs in fexit_sleep (which is the test right after
fexit_bpf2bpf). So looks like this was too early. It seems some CI runs pass on
arm64 but others fail:

  https://github.com/kernel-patches/bpf/actions/runs/9859826851/job/27224868398 (fail)
  https://github.com/kernel-patches/bpf/actions/runs/9859837213/job/27224955045 (pass)

Puranjay, do you have a chance to look into this again?

> > > So, if the lack of Ftrace direct calls would be the reason then the
> > > failure would be due to fexit programs not being supported on arm64.
> > >
> > > But this says that the selftest never returns therefore is not related
> > > to ftrace direct call support but another bug?
> >
> > Fwiw, at least it is passing in the BPF CI now.
> >
> > https://github.com/kernel-patches/bpf/actions/runs/9841781347/job/27169610006