From: Peter Zijlstra <peterz@infradead.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Roy Hopkins <rhopkins@suse.de>,
Joel Fernandes <joel@joelfernandes.org>,
paulmck@kernel.org, Pavel Machek <pavel@denx.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, patches@lists.linux.dev,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
akpm@linux-foundation.org, shuah@kernel.org,
patches@kernelci.org, lkft-triage@lists.linaro.org,
jonathanh@nvidia.com, f.fainelli@gmail.com,
sudipm.mukherjee@gmail.com, srw@sladewatkins.net, rwarsow@gmx.de,
conor@kernel.org, rcu@vger.kernel.org,
Ingo Molnar <mingo@kernel.org>, Kees Cook <keescook@chromium.org>,
Marco Elver <elver@google.com>
Subject: Re: scheduler problems in -next (was: Re: [PATCH 6.4 000/227] 6.4.7-rc1 review)
Date: Tue, 1 Aug 2023 21:08:52 +0200 [thread overview]
Message-ID: <20230801190852.GG11704@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <a05743a3-4dec-6af7-302f-d1d2a0db7d3e@roeck-us.net>
On Tue, Aug 01, 2023 at 10:32:45AM -0700, Guenter Roeck wrote:
> On 7/31/23 14:15, Peter Zijlstra wrote:
> > On Mon, Jul 31, 2023 at 09:34:29AM -0700, Guenter Roeck wrote:
> > > > Ha!, I was poking around the same thing. My hack below seems to (so far,
> > > > <20 boots) help things.
> > > >
> > >
> > > So, dumb question:
> > > How comes this bisects to "sched/fair: Remove sched_feat(START_DEBIT)" ?
> >
> > That commit changes the timings of things; dumb luck otherwise.
>
> Kind of scary. So I only experienced the problem because the START_DEBIT patch
> happened to be queued roughly at the same time, and it might otherwise have
> found its way unnoticed into the upstream kernel. That makes me wonder if this
> or other similar patches may uncover similar problems elsewhere in the kernel
> (i.e., either hide new or existing race conditions or expose existing ones).
>
> This in turn makes me wonder if it would be possible to define a test which
> would uncover such problems without the START_DEBIT patch. Any idea ?
IIRC some of the thread sanitizers use breakpoints to inject random
sleeps, specifically to tickle races.
next prev parent reply other threads:[~2023-08-01 19:09 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-25 10:42 [PATCH 6.4 000/227] 6.4.7-rc1 review Greg Kroah-Hartman
2023-07-25 16:27 ` Jon Hunter
2023-07-25 18:12 ` SeongJae Park
2023-07-25 20:14 ` Shuah Khan
2023-07-25 23:05 ` Florian Fainelli
2023-07-26 6:14 ` Bagas Sanjaya
2023-07-26 9:29 ` Conor Dooley
2023-07-26 9:34 ` Ron Economos
2023-07-26 10:11 ` Naresh Kamboju
2023-07-27 0:03 ` Guenter Roeck
2023-07-27 3:58 ` Joel Fernandes
2023-07-27 11:35 ` Pavel Machek
2023-07-27 13:26 ` Joel Fernandes
2023-07-27 14:06 ` Paul E. McKenney
2023-07-27 14:39 ` Guenter Roeck
2023-07-27 16:07 ` Paul E. McKenney
2023-07-27 17:39 ` Guenter Roeck
2023-07-27 20:33 ` Paul E. McKenney
2023-07-27 23:18 ` Joel Fernandes
[not found] ` <99B56FC7-9474-4968-B1DD-5862572FD0BA@joelfernandes.org>
2023-07-28 22:58 ` Paul E. McKenney
2023-07-29 1:25 ` Joel Fernandes
2023-07-29 5:50 ` Paul E. McKenney
2023-07-30 4:00 ` scheduler problems in -next (was: Re: [PATCH 6.4 000/227] 6.4.7-rc1 review) Guenter Roeck
2023-07-31 14:19 ` Peter Zijlstra
2023-07-31 14:35 ` Guenter Roeck
2023-07-31 14:47 ` Peter Zijlstra
2023-07-31 15:03 ` Guenter Roeck
2023-07-31 14:39 ` Peter Zijlstra
2023-07-31 14:48 ` Guenter Roeck
2023-07-31 14:52 ` Peter Zijlstra
2023-07-31 16:08 ` Roy Hopkins
2023-07-31 16:14 ` Peter Zijlstra
2023-07-31 16:30 ` Roy Hopkins
2023-07-31 16:34 ` Guenter Roeck
2023-07-31 21:15 ` Peter Zijlstra
2023-08-01 17:32 ` Guenter Roeck
2023-08-01 19:08 ` Peter Zijlstra [this message]
2023-08-01 21:32 ` Paul E. McKenney
2023-08-01 19:11 ` Paul E. McKenney
2023-08-01 19:14 ` Paul E. McKenney
2023-08-02 13:57 ` Roy Hopkins
2023-08-02 15:05 ` Paul E. McKenney
2023-08-02 15:31 ` Roy Hopkins
2023-08-02 16:51 ` Paul E. McKenney
2023-08-02 15:45 ` Guenter Roeck
2023-08-02 17:20 ` Paul E. McKenney
2023-08-02 17:14 ` Linus Torvalds
2023-08-02 17:48 ` Paul E. McKenney
2023-07-28 4:22 ` [PATCH 6.4 000/227] 6.4.7-rc1 review Guenter Roeck
2023-07-31 3:54 ` Paul E. McKenney
2023-07-31 3:56 ` Paul E. McKenney
2023-07-31 4:16 ` Guenter Roeck
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