From: Fengguang Wu <fengguang.wu@intel.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org
Subject: Re: lockdep warning on rt_mutex_lock()
Date: Wed, 22 Aug 2012 09:03:32 +0800 [thread overview]
Message-ID: <20120822010332.GA417@localhost> (raw)
In-Reply-To: <20120821192149.GM2456@linux.vnet.ibm.com>
On Tue, Aug 21, 2012 at 12:21:49PM -0700, Paul E. McKenney wrote:
> On Sat, Aug 18, 2012 at 12:59:08PM +0800, Fengguang Wu wrote:
> > On Fri, Aug 17, 2012 at 07:44:37AM -0700, Paul E. McKenney wrote:
> > > On Fri, Aug 17, 2012 at 10:02:40PM +0800, Fengguang Wu wrote:
> > > > On Fri, Aug 17, 2012 at 06:43:28AM -0700, Paul E. McKenney wrote:
> > > > > On Fri, Aug 17, 2012 at 06:06:35PM +0800, Fengguang Wu wrote:
> > > > > > Greetings,
> > > > > >
> > > > > > FYI, a lockdep warning:
> > > > >
> > > > > Certainly looks problematic!
> > > > >
> > > > > Any hint as to what version of the kernel produced this splat?
> > > > > (Yes, lazy of me to ask, I know, but I am not seeing it in my testing.)
> > > >
> > > > It happens on both 3.5.0 and 3.6-rc1. Will bisect (try older kernels) help?
> > > > Bisect is handy for me :)
> > >
> > > Bisection would be very welcome!!! ;-)
> >
> > The bisect result is...
>
> Hmmm... This patch is a bit of a blast from the past.
>
> > commit 9e571a82f0cb205a65a0ea41657f19f22b7fabb8
> > Author: Paul E. McKenney <paul.mckenney@linaro.org>
> > Date: Thu Sep 30 21:26:52 2010 -0700
> >
> > rcu: add tracing for TINY_RCU and TINY_PREEMPT_RCU
> >
> > Add tracing for the tiny RCU implementations, including statistics on
> > boosting in the case of TINY_PREEMPT_RCU and RCU_BOOST.
> >
> > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> So the lockdep complaint indicates that lockdep and the actual hardware
> had different opinions about whether or not interrupts were enabled.
> One way that can happen is through use of raw_local_irq_save(). And this
> commit did add a raw_local_irq_save().
>
> So maybe converting to local_irq_save() will make things work better.
>
> Fengguang, could you please try out the following patch?
It reliably fixed the warnings. Thank you very much!
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
next prev parent reply other threads:[~2012-08-22 1:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-17 10:06 lockdep warning on rt_mutex_lock() Fengguang Wu
2012-08-17 13:43 ` Paul E. McKenney
2012-08-17 14:02 ` Fengguang Wu
2012-08-17 14:44 ` Paul E. McKenney
2012-08-18 4:59 ` Fengguang Wu
2012-08-21 19:21 ` Paul E. McKenney
2012-08-22 1:03 ` Fengguang Wu [this message]
2012-08-17 14:07 ` Fengguang Wu
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