From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752923AbdF1Ao7 (ORCPT ); Tue, 27 Jun 2017 20:44:59 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42508 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753238AbdF1Aov (ORCPT ); Tue, 27 Jun 2017 20:44:51 -0400 Date: Tue, 27 Jun 2017 17:44:46 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org Subject: Re: [BUG] ftrace: WARNING: suspicious RCU usage Reply-To: paulmck@linux.vnet.ibm.com References: <20170627205126.6c5261d10472539b528ca144@kernel.org> <20170627092926.0d712e3a@gandalf.local.home> <20170627225356.318f81d3c687973b7f4f49b1@kernel.org> <20170628075222.03ebbcd22036e8e27d7c7a04@kernel.org> <20170627185743.69d89859@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170627185743.69d89859@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17062800-0056-0000-0000-00000396651A X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007288; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00879663; UDB=6.00438446; IPR=6.00659818; BA=6.00005445; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015981; XFM=3.00000015; UTC=2017-06-28 00:44:48 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17062800-0057-0000-0000-000007CC8324 Message-Id: <20170628004446.GC3721@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-27_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706280011 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 27, 2017 at 06:57:43PM -0400, Steven Rostedt wrote: > On Wed, 28 Jun 2017 07:52:22 +0900 > Masami Hiramatsu wrote: > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index e354e47..442b409 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -973,8 +973,10 @@ static void rcu_eqs_exit(bool user) > > if (oldval & DYNTICK_TASK_NEST_MASK) { > > rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE; > > } else { > > + __this_cpu_inc(disable_rcu_irq_enter); > > rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; > > rcu_eqs_exit_common(oldval, user); > > + __this_cpu_dec(disable_rcu_irq_enter); > > } > > } > > > > Looks like a good fix to me. Paul want to take this one? > > Acked-by: Steven Rostedt (VMware) Why not? How urgent is this, as in what release do you need it in? (Default at this point being v4.14, but non-default available upon request.) Thanx, Paul ------------------------------------------------------------------------ commit 2165b0a9bb37f0560f261986783e7c02bb37c353 Author: Masami Hiramatsu Date: Tue Jun 27 17:41:25 2017 -0700 rcu/tracing: Set disable_rcu_irq_enter on rcu_eqs_exit() Set disable_rcu_irq_enter on not only rcu_eqs_enter_common() but also rcu_eqs_exit(), since rcu_eqs_exit() suffers from the same issue as was fixed for rcu_eqs_enter_common() by commit 03ecd3f48e57 ("rcu/tracing: Add rcu_disabled to denote when rcu_irq_enter() will not work"). Signed-off-by: Masami Hiramatsu Acked-by: Steven Rostedt (VMware) Signed-off-by: Paul E. McKenney diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index ca3076b073e4..2a6b610ef54f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -952,8 +952,10 @@ static void rcu_eqs_exit(bool user) if (oldval & DYNTICK_TASK_NEST_MASK) { rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE; } else { + __this_cpu_inc(disable_rcu_irq_enter); rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; rcu_eqs_exit_common(oldval, user); + __this_cpu_dec(disable_rcu_irq_enter); } }