From: Peter Zijlstra <peterz@infradead.org>
To: Yong Zhang <yong.zhang0@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
rostedt@goodmis.org, Valdis.Kletnieks@vt.edu,
dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com,
patches@linaro.org
Subject: Re: [PATCH RFC tip/core/rcu 7/7] rcu: Quiet RCU-lockdep warnings involving interrupt disabling
Date: Tue, 06 Dec 2011 11:32:07 +0100 [thread overview]
Message-ID: <1323167527.32012.61.camel@twins> (raw)
In-Reply-To: <20111206100537.GA5203@zhy>
On Tue, 2011-12-06 at 18:05 +0800, Yong Zhang wrote:
> On Tue, Dec 06, 2011 at 10:52:32AM +0100, Peter Zijlstra wrote:
> > On Tue, 2011-12-06 at 09:26 +0800, Yong Zhang wrote:
> >
> > > Yeah, because we call might_sleep() in rt_mutex_lock() unconditionally.
> > > But in this case the 'BUG: sleeping function called from invalid context
> > > at *' is obviously false positive.
> >
> > Why can't this mutex acquisition not block?
>
> It could block. The issue it's legal to call rt_mutex_lock() with
> irqs disabled and we don't want might_sleep() bite us on this
Of course its legal (nobody will arrest you for it), but its also bloody
horrid.
> special case. When we are going to sleep, we re-enable irq in
> __rt_mutex_slowlock().
>
> >
> > > Maybe we could teach might_sleep() about this special case?
> >
> > Sounds horrid.
>
> Maybe, any alternative?
Maybe someone explain this mess first?
next prev parent reply other threads:[~2011-12-06 10:32 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-03 18:34 [PATCH tip/core/rcu 0/7] Preview of fourth set of RCU changes for 3.3 Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 1/7] rcu: Don't check irq nesting from rcu idle entry/exit Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 2/7] rcu: Irq nesting is always 0 on rcu_enter_idle_common Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 3/7] rcu: Keep invoking callbacks if CPU otherwise idle Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 4/7] rcu: Adaptive dyntick-idle preparation Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 5/7] rcu: remove redundant rcu_cpu_stall_suppress declaration Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 6/7] driver-core/cpu: Add cpu_is_hotpluggable() for rcutorture error analysis Paul E. McKenney
2011-12-03 21:06 ` Josh Triplett
2011-12-03 23:14 ` Paul E. McKenney
2011-12-03 18:34 ` [PATCH RFC tip/core/rcu 7/7] rcu: Quiet RCU-lockdep warnings involving interrupt disabling Paul E. McKenney
2011-12-05 9:19 ` Yong Zhang
2011-12-05 16:45 ` Paul E. McKenney
2011-12-06 1:26 ` Yong Zhang
2011-12-06 2:12 ` Paul E. McKenney
2011-12-06 3:27 ` [PATCH 1/3] kernel.h: sched: introduce might_sleep_disabled() Yong Zhang
2011-12-06 3:28 ` [PATCH 2/3] rtmutex: introduce rt_mutex_lock_irqdisabled() Yong Zhang
2011-12-06 3:29 ` [PATCH 3/3] rcu: use rt_mutex_lock_irqdisabled() in rcu_boost() Yong Zhang
2011-12-06 9:52 ` [PATCH RFC tip/core/rcu 7/7] rcu: Quiet RCU-lockdep warnings involving interrupt disabling Peter Zijlstra
2011-12-06 10:05 ` Yong Zhang
2011-12-06 10:32 ` Peter Zijlstra [this message]
2011-12-06 12:26 ` Steven Rostedt
2011-12-06 16:04 ` Paul E. McKenney
2011-12-06 16:33 ` Paul E. McKenney
2011-12-06 16:56 ` Steven Rostedt
2011-12-06 17:16 ` Paul E. McKenney
2011-12-06 10:27 ` Peter Zijlstra
2011-12-06 16:11 ` Paul E. McKenney
2011-12-06 16:14 ` Peter Zijlstra
2011-12-06 16:01 ` Paul E. McKenney
2011-12-05 9:41 ` Peter Zijlstra
2011-12-05 10:03 ` Yong Zhang
2011-12-05 16:48 ` Paul E. McKenney
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