From: Peter Zijlstra <peterz@infradead.org>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Dave Jones <davej@codemonkey.org.uk>,
Viresh Kumar <viresh.kumar@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-pm@vger.kernel.org
Subject: Re: cpufreq/ondemand: unpinning an unpinned lock.
Date: Wed, 22 Jul 2015 11:02:56 +0200 [thread overview]
Message-ID: <20150722090256.GP25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <55AEE7D8.3000507@codeaurora.org>
On Tue, Jul 21, 2015 at 05:46:16PM -0700, Stephen Boyd wrote:
> On 07/16/2015 05:42 AM, Dave Jones wrote:
> >On Thu, Jul 16, 2015 at 10:41:50AM +0530, Viresh Kumar wrote:
> >
> > > > > WARNING: CPU: 1 PID: 29529 at kernel/locking/lockdep.c:3497 lock_unpin_lock+0x109/0x110()
> > > > > unpinning an unpinned lock
> > > > > Call Trace:
> > > > > [<ffffffffae0d0ec9>] lock_unpin_lock+0x109/0x110
> > > > > [<ffffffffae7f93cc>] __schedule+0x3ac/0xb60
> > > > > [<ffffffffae7f9c41>] schedule+0x41/0x90
> > > > > [<ffffffffae7f9ff8>] schedule_preempt_disabled+0x18/0x30
> Lock pinning is new in v4.2-rc1. Adding Peter just in case there's some
> insight.
Hmm, weird. I've not seen it happen before.
There's potentially 3 unpin's in __schedule():
- the obvious one in the prev == next case,
- the on in context_switch(),
- the on in try_to_wake_up_local().
All 3 appear to be balanced; the first and second against the pin_lock()
at the start of __schedule() and the third against that and it repins
the lock against the first two.
Most curious.
prev parent reply other threads:[~2015-07-22 9:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 22:04 cpufreq/ondemand: unpinning an unpinned lock Dave Jones
2015-07-16 0:13 ` Rafael J. Wysocki
2015-07-16 5:11 ` Viresh Kumar
2015-07-16 12:42 ` Dave Jones
2015-07-22 0:46 ` Stephen Boyd
2015-07-22 9:02 ` Peter Zijlstra [this message]
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