From: Steven Rostedt <rostedt@goodmis.org>
To: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: RFC: SysRq nice-all-RT-tasks is broken
Date: Wed, 8 Mar 2017 11:51:14 -0500 [thread overview]
Message-ID: <20170308115114.4e20fc73@gandalf.local.home> (raw)
In-Reply-To: <be47a577-7dfe-a7b3-57e0-1f182edc568b@linux.vnet.ibm.com>
On Wed, 8 Mar 2017 16:23:35 +0100
Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote:
> I got it on Power and on X86_64, but I guess it should happen in all
> architectures.
> Here are the steps to recreate it :
> 1. Create a RT task : sudo chrt -f 50 /bin/sleep 999999
> 2. On the console trigger the 'nice-all-RT-tasks' SYS-RQ.
>
> The panic is triggered by the BUG_ON(in_interrupt()) introduced by this
> commit:
>
> 66e5393a78b3 ("[PATCH] BUG() if setscheduler is called from interrupt
> context")
>
> Since SysRq is run from the interrupt context, the panic is expected.
>
> Looking at the code, I'm wondering if the BUG_ON() is still required in
> __sched_setscheduler(). But I'm not so confident, so requesting your
> advise here.
>
Hmm, that commit was added in 2.6.18, and you're right, a lot has
changed since then. Have you tried removing it and running it under
lockdep, and see if it triggers any warnings?
-- Steve
next prev parent reply other threads:[~2017-03-08 16:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-08 15:23 RFC: SysRq nice-all-RT-tasks is broken Laurent Dufour
2017-03-08 16:51 ` Steven Rostedt [this message]
2017-03-08 16:57 ` Steven Rostedt
2017-03-08 17:03 ` Laurent Dufour
2017-03-08 17:40 ` Steven Rostedt
2017-03-08 17:46 ` Steven Rostedt
2017-03-09 9:02 ` Laurent Dufour
2017-05-23 8:46 ` [tip:sched/core] sched/core: Allow __sched_setscheduler() in interrupts when PI is not used tip-bot for Steven Rostedt (VMware)
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