linux-kernel - Re: [PATCH bpf] selftests/bpf: DENYLIST.aarch64: Remove fexit

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Message-ID: <CACYkzJ5E+3xYkNsH7JoVkjabzSwnZZCzzTz5B50qDB7bLYkmMA@mail.gmail.com>
Date: Mon, 8 Jul 2024 18:42:31 +0200
From: KP Singh <kpsingh@...nel.org>
To: Daniel Borkmann <daniel@...earbox.net>
Cc: Puranjay Mohan <puranjay@...nel.org>, Andrii Nakryiko <andrii@...nel.org>, 
	Eduard Zingerman <eddyz87@...il.com>, Mykola Lysenko <mykolal@...com>, Alexei Starovoitov <ast@...nel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
	Shuah Khan <shuah@...nel.org>, bpf@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Manu Bretelle <chantra@...a.com>, 
	Florent Revest <revest@...gle.com>
Subject: Re: [PATCH bpf] selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep

On Mon, Jul 8, 2024 at 6:09 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 7/8/24 5:35 PM, Puranjay Mohan wrote:
> > Daniel Borkmann <daniel@...earbox.net> writes:
> >
> >> On 7/8/24 5:26 PM, KP Singh wrote:
> >>> On Mon, Jul 8, 2024 at 5:00 PM Puranjay Mohan <puranjay@...nel.org> wrote:
> >>>>
> >>>> Daniel Borkmann <daniel@...earbox.net> 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@chromium.org/
> >>> 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.

- KP

> >
> > 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