Date: Sun, 27 Mar 2016 14:07:33 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        "Chatre, Reinette" <reinette.chatre@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Josh Triplett <josh@joshtriplett.org>, Ross Green <rgkernel@gmail.com>,
        John Stultz <john.stultz@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>, dipankar@in.ibm.com,
        Andrew Morton <akpm@linux-foundation.org>,
        rostedt <rostedt@goodmis.org>, David Howells <dhowells@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        Darren Hart <dvhart@linux.intel.com>,
        =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, pranith kumar <bobby.prani@gmail.com>
Subject: Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17
Message-ID: <20160327210733.GC4287@linux.vnet.ibm.com>
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On Sun, Mar 27, 2016 at 10:53:18PM +0200, Peter Zijlstra wrote:
> On Sun, Mar 27, 2016 at 08:40:18AM -0700, Paul E. McKenney wrote:
> > Oh, and the patch I am running with is below.  I am running x86, and so
> > some other architectures would of course need the corresponding patch
> > on that architecture.
> 
> > -#define TIF_POLLING_NRFLAG	21	/* idle is polling for TIF_NEED_RESCHED */
> 
> Also note that ARM (v7) which Ross is running doesn't have this to begin
> with.

He might well be seeing some other bug, then.  Reinette might be instead
seeing time-synchronization issues, perhaps that is also Ross's problem.

Or maybe there is more than one bug.  ;-)

							Thanx, Paul