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From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>,
	Christian Engelmayer <cengelma@gmx.at>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PROBLEM] possible divide by 0 in kernel/sched/cputime.c scale_stime()
Date: Mon, 18 Nov 2013 16:39:41 +0100	[thread overview]
Message-ID: <20131118153941.GA28699@gmail.com> (raw)
In-Reply-To: <20131118141956.GB10022@twins.programming.kicks-ass.net>


* Peter Zijlstra <peterz@infradead.org> wrote:

> I would be tempted to say you should simply mark the tsc unstable on 
> boot and live with that -- we fully assume the sched_clock stuff is 
> not going backwards in an 'observable' way.

BIOS crap and actual hardware bugs do happen - so kernel code needs to 
consider TSC input with a pinch of salt, assuming that it's untrusted 
external data.

> That said, it might be nice to not crash either..

Indeed, not crashing on weird TSC input is absolutely required!

Thanks,

	Ingo

  reply	other threads:[~2013-11-18 15:39 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-16 21:37 [PROBLEM] possible divide by 0 in kernel/sched/cputime.c scale_stime() Christian Engelmayer
2013-11-18 14:02 ` Stanislaw Gruszka
2013-11-18 14:19   ` Peter Zijlstra
2013-11-18 15:39     ` Ingo Molnar [this message]
2013-11-18 17:27   ` Peter Zijlstra
2013-11-20 12:08     ` Stanislaw Gruszka
2013-11-25  0:43       ` Christian Engelmayer
2013-11-26 14:44         ` [PATCH] sched, fair: Rework sched_fair time accounting Peter Zijlstra
2013-12-12  9:52     ` [tip:sched/urgent] sched/fair: " tip-bot for Peter Zijlstra

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