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From: Jakub Kicinski <kuba@kernel.org>
To: Matthieu Baerts <matttbe@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>,
	netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
	pabeni@redhat.com, paulmck@kernel.org, joel@joelfernandes.org,
	steven.price@arm.com, akpm@linux-foundation.org,
	anshuman.khandual@arm.com, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH net-next] configs/debug: run and debug PREEMPT
Date: Tue, 8 Apr 2025 12:03:18 -0700	[thread overview]
Message-ID: <20250408120318.65125876@kernel.org> (raw)
In-Reply-To: <df253016-81df-4cc9-8a8c-f92fd1cb8aea@kernel.org>

On Tue, 8 Apr 2025 20:18:26 +0200 Matthieu Baerts wrote:
> On 02/04/2025 19:23, Stanislav Fomichev wrote:
> > Recent change [0] resulted in a "BUG: using __this_cpu_read() in
> > preemptible" splat [1]. PREEMPT kernels have additional requirements
> > on what can and can not run with/without preemption enabled.
> > Expose those constrains in the debug kernels.  
> 
> Good idea to suggest this to find more bugs!
> 
> I did some quick tests on my side with our CI, and the MPTCP selftests
> seem to take a bit more time, but without impacting the results.
> Hopefully, there will be no impact in slower/busy environments :)

What kind of slow down do you see? I think we get up to 50% more time
spent in the longer tests. Not sure how bad is too bad.. I'm leaning
towards applying this to net-next and we can see if people running
on linux-next complain?

Let me CC kselftests, patch in question:
https://lore.kernel.org/all/20250402172305.1775226-1-sdf@fomichev.me/

  reply	other threads:[~2025-04-08 19:03 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-02 17:23 [PATCH net-next] configs/debug: run and debug PREEMPT Stanislav Fomichev
2025-04-04  9:32 ` Simon Horman
2025-04-08 18:18 ` Matthieu Baerts
2025-04-08 19:03   ` Jakub Kicinski [this message]
2025-04-09 11:58     ` Matthieu Baerts
2025-04-09 15:55       ` Jakub Kicinski
2025-04-10  1:00 ` patchwork-bot+netdevbpf

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