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

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Message-ID: <BF0DCCB8-EB5D-433D-87C0-3FA82E2C09EC@meta.com>
Date: Fri, 12 Jul 2024 19:59:47 +0000
From: Manu Bretelle <chantra@...a.com>
To: Puranjay Mohan <puranjay12@...il.com>
CC: Puranjay Mohan <puranjay@...nel.org>,
        Daniel Borkmann
	<daniel@...earbox.net>, KP Singh <kpsingh@...nel.org>,
        Andrii Nakryiko
	<andrii@...nel.org>,
        Eduard Zingerman <eddyz87@...il.com>,
        Mykola Lysenko
	<mykolal@...a.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"
	<bpf@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org"
	<linux-kselftest@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        Florent Revest <revest@...gle.com>
Subject: Re: [PATCH bpf] selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep



> On Jul 12, 2024, at 11:08 AM, Puranjay Mohan <puranjay12@...il.com> wrote:
> 
> Thanks for testing the fix.
> 
> This bug has been resolved now but the test still hangs sometimes.
> Unfortunately, I am not able to reproduce this hang
> using vmtest.

I have not able to reproduce the original error either. I will try to reproduce on the actual CI host next week (which are native arm64 host compared to my local setup which uses full emulation).

> Can you extract some logs from the CI somehow?? If it is
> hanging in the kernel there should be some
> soft lockup or RCU lockup related messages.

I think once we execute the test, vmtest does not track the console logs anymore, so we won’t see those. That should be fixable, but for now, I won’t be able to get more logs than you get from the UI currently.
> 
> I was talking about this with Kumar and we think that this test is
> hanging in the userspace in the following loop:
> 
> while (READ_ONCE(fexit_skel->bss->fentry_cnt) != 2);
> 
> Could it be that fentry_cnt is > 2 somehow before we reach this?? This
> is only a random guess though.
> 


Manu