linux-kernel - Re: [RFC PATCH 0/2] sysctl: Panic on RCU stall and schedule while atomic

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Date:	Tue, 31 May 2016 21:27:24 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Daniel Bristot de Oliveira <bristot@...hat.com>,
	linux-kernel@...r.kernel.org
Cc:	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>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Subject: Re: [RFC PATCH 0/2] sysctl: Panic on RCU stall and schedule while
 atomic

On 05/31/2016 09:07 PM, Daniel Bristot de Oliveira wrote:
> This patch series implements two kernel.panic_on_* like sysctl:
> 
> kernel.panic_on_rcu_stall:
> 	panic() on RCU Stall detection.
> 
> kernel.panic_on_sched_in_atomic:
> 	panic() on schedule while atomic detection.
> 
> These sysctls are useful to capture a vmcore when is not possible
> to recompile the kernel to include the panic() call. For instance
> when supporting enterprise users.
> 
> Daniel Bristot de Oliveira (2):
>   rcu: sysctl: Panic on RCU Stall
>   sched: sysctl: Panic on scheduling while atomic
> 
>  Documentation/sysctl/kernel.txt | 25 +++++++++++++++++++++++++
>  include/linux/kernel.h          |  2 ++
>  kernel/rcu/tree.c               |  8 ++++++++
>  kernel/sched/core.c             |  7 +++++++
>  kernel/sysctl.c                 | 20 ++++++++++++++++++++
>  5 files changed, 62 insertions(+)

Acked-by: Christian Borntraeger <borntraeger@...ibm.com>

for both changes. I too often had to add manual panics in a test
kernel and reproduce an issue. This will allow to take a (k)dump at a point
in time where the data structures might still explain what happened.
As this is an opt-in nobody, this should not cause any trouble for
people that do not want to take dumps.

Christian