From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754686Ab2HaSYj (ORCPT ); Fri, 31 Aug 2012 14:24:39 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:52255 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754440Ab2HaSYi (ORCPT ); Fri, 31 Aug 2012 14:24:38 -0400 X-Originating-IP: 217.70.178.147 X-Originating-IP: 173.246.103.110 Date: Fri, 31 Aug 2012 11:24:29 -0700 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" Subject: Re: [PATCH tip/core/rcu 11/15] rcu: Avoid spurious RCU CPU stall warnings Message-ID: <20120831182429.GI4259@jtriplet-mobl1> References: <20120830185607.GA32148@linux.vnet.ibm.com> <1346352988-32444-1-git-send-email-paulmck@linux.vnet.ibm.com> <1346352988-32444-11-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1346352988-32444-11-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 30, 2012 at 11:56:24AM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" > > If a given CPU avoids the idle loop but also avoids starting a new > RCU grace period for a full minute, RCU can issue spurious RCU CPU > stall warnings. This commit fixes this issue by adding a check for > ongoing grace period to avoid these spurious stall warnings. > > Reported-by: Becky Bruce > Signed-off-by: Paul E. McKenney > Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett > --- > kernel/rcutree.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index fbe43b0..e58097b 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -820,7 +820,8 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) > j = ACCESS_ONCE(jiffies); > js = ACCESS_ONCE(rsp->jiffies_stall); > rnp = rdp->mynode; > - if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { > + if (rcu_gp_in_progress(rsp) && > + (ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { > > /* We haven't checked in, so go dump stack. */ > print_cpu_stall(rsp); > -- > 1.7.8 >