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Date: Wed, 1 Jun 2016 11:45:44 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
Subject: Re: [RFC PATCH 2/2] sched: sysctl: Panic on scheduling while atomic
Message-ID: <20160601094544.GP3190@twins.programming.kicks-ass.net>
References: <cover.1464652607.git.bristot@redhat.com>
 <654ac2ba100f609917b68d1c6a33331ec9df8da4.1464652607.git.bristot@redhat.com>
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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?