From: Eduard Zingerman <eddyz87@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@kernel.org>,
kkd@meta.com, kernel-team@meta.com
Subject: Re: [PATCH bpf-next v1] selftests/bpf: Add ABBCCA case for rqspinlock stress test
Date: Wed, 22 Oct 2025 15:04:51 -0700 [thread overview]
Message-ID: <93e428555500f60c3dbcb04b79807d3ffce024c5.camel@gmail.com> (raw)
In-Reply-To: <20251022175402.211176-1-memxor@gmail.com>
On Wed, 2025-10-22 at 17:54 +0000, Kumar Kartikeya Dwivedi wrote:
> Introduce a new mode for the rqspinlock stress test that exercises a
> deadlock that won't be detected by the AA and ABBA checks, such that we
> always reliably trigger the timeout fallback. We need 4 CPUs for this
> particular case, as CPU 0 is untouched, and three participant CPUs for
> triggering the ABBCCA case.
>
> Refactor the lock acquisition paths in the module to better reflect the
> three modes and choose the right lock depending on the context.
>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
The overhaul makes sense to me and the code is easy to follow.
The only nit I have is that test does not fail if deadlock is not detected.
E.g. if I remove raw_res_spin_unlock_irqrestore() call in nmi_cb(),
there are stall splats in dmesg, but test harness reports success.
I suggest adding some signal that all kthreads terminated successfully.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2025-10-22 22:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-22 17:54 [PATCH bpf-next v1] selftests/bpf: Add ABBCCA case for rqspinlock stress test Kumar Kartikeya Dwivedi
2025-10-22 22:04 ` Eduard Zingerman [this message]
2025-10-24 16:42 ` Amery Hung
2025-10-24 16:49 ` Eduard Zingerman
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