linux-kernel - Re: [RFC PATCH 2/2] sched: sysctl: Panic on scheduling while atomic

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Message-ID: <20160601094544.GP3190@twins.programming.kicks-ass.net>
Date:	Wed, 1 Jun 2016 11:45:44 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Daniel Bristot de Oliveira <bristot@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Subject: Re: [RFC PATCH 2/2] sched: sysctl: Panic on scheduling while atomic

On Tue, May 31, 2016 at 04:07:33PM -0300, Daniel Bristot de Oliveira wrote:
> Currently, a schedule while atomic error prints the stack trace to the
> kernel log and the system continue running.
> 
> Although it is possible to collect the kernel log messages and analyse
> it, often more information are needed. Furthermore, keep the system
> running is not always the best choice. For example, when the preempt
> count underflows the system will not stop to complain about scheduling
> while atomic, so the kernel log can wraparound overwriting the first
> stack trace, tuning the analysis even more difficult.
> 
> This patch implements the kernel.panic_on_sched_in_atomic sysctl to
> help out on these more complex situations.
> 
> When kernel.panic_on_sched_in_atomic is set to 1, the kernel will
> panic() in the schedule while atomic detection.

Do we really need more panic_on_* knobs? Can't we re-purpose
panic_on_warn for this?