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Date: Wed, 4 Nov 2015 17:59:03 -0800 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Andi Kleen <andi@...stfloor.org> Cc: Peter Zijlstra <peterz@...radead.org>, Dave Jones <davej@...emonkey.org.uk>, Linux Kernel <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>, Stephane Eranian <eranian@...il.com> Subject: Re: perf related lockdep bug On Wed, Nov 04, 2015 at 04:55:28PM -0800, Paul E. McKenney wrote: > On Wed, Nov 04, 2015 at 09:58:36PM +0100, Andi Kleen wrote: > > > > I tested my perf stress workload with the patch applied on 4.3, > > unfortunately got a hang again :-/ > > Any diagnostics, sysrq-T output, or whatever? Given that it looks like your hang is happening at runtime, I would guess that the following patch won't help, but who knows? Thanx, Paul ------------------------------------------------------------------------ commit 05faf451f1239a28fcd63bf4b66c0db57d7b13f9 Author: Peter Zijlstra <peterz@...radead.org> Date: Wed Nov 4 08:22:05 2015 -0800 rcu: Move wakeup out from under rnp->lock This patch removes a potential deadlock hazard by moving the wake_up_process() in rcu_spawn_gp_kthread() out from under rnp->lock. Signed-off-by: Peter Zijlstra <peterz@...radead.org> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index caf3651fa5c9..183445959d00 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4323,8 +4323,8 @@ static int __init rcu_spawn_gp_kthread(void) sp.sched_priority = kthread_prio; sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); } - wake_up_process(t); raw_spin_unlock_irqrestore(&rnp->lock, flags); + wake_up_process(t); } rcu_spawn_nocb_kthreads(); rcu_spawn_boost_kthreads(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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