From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Ben Greear <greearb@candelatech.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ed Tomlinson <edt@aei.ca>,
linux-kernel@vger.kernel.org, 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,
edward.tomlinson@aero.bombardier.com
Subject: Re: [PATCH rcu/urgent 0/6] Fixes for RCU/scheduler/irq-threads trainwreck
Date: Wed, 20 Jul 2011 13:06:39 -0700 [thread overview]
Message-ID: <20110720200639.GO2313@linux.vnet.ibm.com> (raw)
In-Reply-To: <1311189946.29152.88.camel@twins>
On Wed, Jul 20, 2011 at 09:25:46PM +0200, Peter Zijlstra wrote:
> On Wed, 2011-07-20 at 12:01 -0700, Paul E. McKenney wrote:
> > This can interact badly with the recently
> > added RCU read-side critical sections in the scheduler that have
> > either the runqueue or the priority-inheritance locks held, especially
> > when interrupts occur towards the end of __rcu_read_unlock().
>
> Right, so while I recently added a lot more, there have been rcu usage
> sites under rq->lock for a long while, see commits
>
> a18b83b7ef ("cpuacct: make cpuacct hierarchy walk in cpuacct_charge()
> safe when rcupreempt is used -v2") -- March 2009.
>
> f3b577dec1 ("rcu: apply RCU protection to wake_affine()") -- Jun 2010
>
> b0a0f667 ("sched: suppress RCU lockdep splat in task_fork_fair") -- Oct
> 2010
>
> So I'm not quite seeing how the problems we're hitting now are new.
My guess is that the problem has been there for quite some time, but
that the probability of hitting it has increased, at least for some
combinations of config options.
Thanx, Paul
next prev parent reply other threads:[~2011-07-20 20:06 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 0:17 [PATCH rcu/urgent 0/6] Fixes for RCU/scheduler/irq-threads trainwreck Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 1/7] rcu: decrease rcu_report_exp_rnp coupling with scheduler Paul E. McKenney
2011-07-20 2:40 ` Peter Zijlstra
2011-07-20 4:54 ` Paul E. McKenney
2011-07-20 11:23 ` Ed Tomlinson
2011-07-20 11:31 ` Ed Tomlinson
2011-07-20 12:35 ` Peter Zijlstra
2011-07-20 13:23 ` Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 2/7] rcu: Fix RCU_BOOST race handling current->rcu_read_unlock_special Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 3/7] rcu: Streamline code produced by __rcu_read_unlock() Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 4/7] rcu: protect __rcu_read_unlock() against scheduler-using irq handlers Paul E. McKenney
2011-07-20 12:54 ` Peter Zijlstra
2011-07-20 13:25 ` Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 5/7] sched: Add irq_{enter,exit}() to scheduler_ipi() Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 6/7] softirq,rcu: Inform RCU of irq_exit() activity Paul E. McKenney
2011-07-20 0:18 ` [PATCH tip/core/urgent 7/7] signal: align __lock_task_sighand() irq disabling and RCU Paul E. McKenney
2011-07-20 1:10 ` [PATCH rcu/urgent 0/6] Fixes for RCU/scheduler/irq-threads trainwreck Ben Greear
2011-07-20 1:30 ` Ed Tomlinson
2011-07-20 2:07 ` Ed Tomlinson
2011-07-20 4:44 ` Paul E. McKenney
2011-07-20 5:03 ` Linus Torvalds
2011-07-20 13:34 ` Paul E. McKenney
2011-07-20 17:02 ` Ben Greear
2011-07-20 17:15 ` Paul E. McKenney
2011-07-20 18:44 ` Ingo Molnar
2011-07-20 18:52 ` Peter Zijlstra
2011-07-20 19:01 ` Paul E. McKenney
2011-07-20 19:25 ` Peter Zijlstra
2011-07-20 20:06 ` Paul E. McKenney [this message]
2011-07-20 19:02 ` Linus Torvalds
2011-07-20 19:29 ` Paul E. McKenney
2011-07-20 19:39 ` Ingo Molnar
2011-07-20 19:57 ` Ingo Molnar
2011-07-20 20:33 ` Paul E. McKenney
2011-07-20 20:54 ` Ben Greear
2011-07-20 21:12 ` Paul E. McKenney
2011-07-21 3:25 ` Ben Greear
2011-07-21 16:04 ` Paul E. McKenney
2011-07-20 21:04 ` [GIT PULL] RCU fixes for v3.0 Ingo Molnar
2011-07-20 21:55 ` Ed Tomlinson
2011-07-20 22:06 ` Paul E. McKenney
2011-07-20 20:08 ` [PATCH rcu/urgent 0/6] Fixes for RCU/scheduler/irq-threads trainwreck Paul E. McKenney
2011-07-20 21:05 ` Peter Zijlstra
2011-07-20 21:39 ` Paul E. McKenney
2011-07-20 10:49 ` Ed Tomlinson
2011-07-20 18:25 ` [PATCH rcu/urgent 0/7 v2] " Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 1/7] rcu: decrease rcu_report_exp_rnp coupling with scheduler Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 2/7] rcu: Fix RCU_BOOST race handling current->rcu_read_unlock_special Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 3/7] rcu: Streamline code produced by __rcu_read_unlock() Paul E. McKenney
2011-07-20 22:44 ` Linus Torvalds
2011-07-21 5:09 ` Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 4/7] rcu: protect __rcu_read_unlock() against scheduler-using irq handlers Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 5/7] sched: Add irq_{enter,exit}() to scheduler_ipi() Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 6/7] softirq,rcu: Inform RCU of irq_exit() activity Paul E. McKenney
2011-07-20 18:26 ` [PATCH tip/core/urgent 7/7] signal: align __lock_task_sighand() irq disabling and RCU Paul E. McKenney
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