From: Luming Yu <luming.yu@gmail.com>
To: paulmck@kernel.org
Cc: Andi Kleen <ak@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
john.stultz@linaro.org, sboyd@kernel.org, corbet@lwn.net,
Mark.Rutland@arm.com, maz@kernel.org, kernel-team@fb.com,
neeraju@codeaurora.org, feng.tang@intel.com,
zhengjun.xing@intel.com, Chris Mason <clm@fb.com>
Subject: Re: [PATCH v10 clocksource 1/7] clocksource: Provide module parameters to inject delays in watchdog
Date: Wed, 28 Apr 2021 12:49:12 +0800 [thread overview]
Message-ID: <CAJRGBZxgJuc2OJfvT_k3Xmk_qsxzm=xX5wm4NqeRo7vkTcZk6w@mail.gmail.com> (raw)
In-Reply-To: <20210426182433.GD975577@paulmck-ThinkPad-P17-Gen-1>
We 'd expect to see clock_source watchdog can avoid to do wrong thing
due to the injected delay or
in real life delay by doing tsc sync-re-check by applying the patch-set.
However , the noise is still cause wrong actions and the patch doesn't
defeat the injected's delay
please correct me if I'm wrong.
parameters]# cat *
1
1
-1
3
8
[62939.809615] clocksource: clocksource_watchdog_inject_delay():
Injecting delay.
[62939.816867] clocksource: clocksource_watchdog_inject_delay():
Injecting delay.
[62939.824094] clocksource: clocksource_watchdog_inject_delay():
Injecting delay.
[62939.831314] clocksource: clocksource_watchdog_inject_delay():
Injecting delay.
[62939.838536] clocksource: timekeeping watchdog on CPU26: hpet
read-back delay of 7220833ns, attempt 4, marking unstable
[62939.849230] tsc: Marking TSC unstable due to clocksource watchdog
[62939.855340] TSC found unstable after boot, most likely due to
broken BIOS. Use 'tsc=unstable'.
[62939.863972] sched_clock: Marking unstable (62943398530130,
-3543150114)<-(62941186607503, -1331276112)
[62939.875104] clocksource: Checking clocksource tsc synchronization
from CPU 123 to CPUs 0,6,26,62,78,97-98,137.
[62939.886518] clocksource: Switched to clocksource hpet
On Tue, Apr 27, 2021 at 2:27 AM Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Mon, Apr 26, 2021 at 10:56:27AM -0700, Andi Kleen wrote:
> > > ------------------------------------------------------------------------
> > >
> > > - module parameters
> > >
> > > If the scope of the fault injection capability is limited to a
> > > single kernel module, it is better to provide module parameters to
> > > configure the fault attributes.
> > >
> > > ------------------------------------------------------------------------
> > >
> > > And in this case, the fault injection capability is in fact limited to
> > > kernel/clocksource.c.
> >
> >
> > I disagree with this recommendation because it prevents fuzzer coverage.
> >
> > Much better to have an uniform interface that can be automatically
> > explored.
>
> The permissions for these module parameters is 0644, so there is no
> reason why the fuzzers cannot use them via sysfs.
>
> Thanx, Paul
next prev parent reply other threads:[~2021-04-28 4:54 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-25 22:45 [PATCH v10 clocksource 0/7] Do not mark clocks unstable due to delays for v5.13 Paul E. McKenney
2021-04-25 22:47 ` [PATCH v10 clocksource 1/7] clocksource: Provide module parameters to inject delays in watchdog Paul E. McKenney
2021-04-26 4:07 ` Andi Kleen
2021-04-26 7:13 ` Thomas Gleixner
2021-04-26 15:28 ` Paul E. McKenney
2021-04-26 16:00 ` Andi Kleen
2021-04-26 16:14 ` Paul E. McKenney
2021-04-26 17:56 ` Andi Kleen
2021-04-26 18:24 ` Paul E. McKenney
2021-04-28 4:49 ` Luming Yu [this message]
2021-04-28 13:57 ` Paul E. McKenney
2021-04-28 14:24 ` Luming Yu
2021-04-28 14:37 ` Thomas Gleixner
2021-04-25 22:47 ` [PATCH v10 clocksource 2/7] clocksource: Retry clock read if long delays detected Paul E. McKenney
2021-04-27 1:44 ` Feng Tang
2021-04-25 22:47 ` [PATCH v10 clocksource 3/7] clocksource: Check per-CPU clock synchronization when marked unstable Paul E. McKenney
2021-04-26 4:12 ` Andi Kleen
2021-04-26 7:16 ` Thomas Gleixner
2021-04-25 22:47 ` [PATCH v10 clocksource 4/7] clocksource: Provide a module parameter to fuzz per-CPU clock checking Paul E. McKenney
2021-04-25 22:47 ` [PATCH v10 clocksource 5/7] clocksource: Limit number of CPUs checked for clock synchronization Paul E. McKenney
2021-04-25 22:47 ` [PATCH v10 clocksource 6/7] clocksource: Forgive tsc_early pre-calibration drift Paul E. McKenney
2021-04-26 15:01 ` Feng Tang
2021-04-26 15:25 ` Paul E. McKenney
2021-04-26 15:36 ` Feng Tang
2021-04-26 18:26 ` Paul E. McKenney
2021-04-27 1:13 ` Feng Tang
2021-04-27 3:46 ` Paul E. McKenney
2021-04-27 4:16 ` Feng Tang
2021-04-26 15:28 ` Thomas Gleixner
2021-04-27 21:03 ` Thomas Gleixner
2021-04-27 7:27 ` [clocksource] 8c30ace35d: WARNING:at_kernel/time/clocksource.c:#clocksource_watchdog kernel test robot
2021-04-27 8:45 ` Feng Tang
2021-04-27 13:37 ` Paul E. McKenney
2021-04-27 17:50 ` Paul E. McKenney
2021-04-27 21:09 ` Thomas Gleixner
2021-04-28 1:48 ` Paul E. McKenney
2021-04-28 10:14 ` Thomas Gleixner
2021-04-28 18:31 ` Paul E. McKenney
2021-04-28 13:34 ` Thomas Gleixner
2021-04-28 15:39 ` Peter Zijlstra
2021-04-28 17:00 ` Thomas Gleixner
2021-04-29 7:38 ` Feng Tang
2021-04-28 18:31 ` Paul E. McKenney
2021-04-29 8:27 ` Thomas Gleixner
2021-04-29 14:26 ` Paul E. McKenney
2021-04-29 17:30 ` Thomas Gleixner
2021-04-29 23:04 ` Andi Kleen
2021-04-30 0:24 ` Paul E. McKenney
2021-04-30 0:59 ` Paul E. McKenney
2021-04-30 5:08 ` Paul E. McKenney
2021-04-25 22:47 ` [PATCH v9 clocksource 6/6] clocksource: Reduce WATCHDOG_THRESHOLD Paul E. McKenney
2021-04-25 22:47 ` [PATCH v10 clocksource 7/7] " Paul E. McKenney
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