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

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Message-ID: <e38a7f99-b3d1-adaf-26b3-800a6628d98f@redhat.com>
Date:	Wed, 1 Jun 2016 10:37:11 -0300
From:	Daniel Bristot de Oliveira <daolivei@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
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 06/01/2016 06:45 AM, Peter Zijlstra wrote:
> Do we really need more panic_on_* knobs? Can't we re-purpose
> panic_on_warn for this?

I think this case is very specific, specific enough to deserve its own
sysctl. But I see your point, and the possibilities I can see are:

1) convert the printk(KERN_ERR "BUG:...") to a WARN(1,"BUG:..."), but
this will hide all other information printed in the function, so -1 for
this option;

2) fire a WARN in the end of the function with a message like the
previous printk(); or

3) re-use the panic_on_warn variable to condition the panic,
or to force a WARN.

But, IMHO, I think these are not as polish as use a specific sysctl.

If you think that any of these options are better than what I propose,
I can cook a v2 with the best option :-).

-- Daniel