From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755244Ab2HAASp (ORCPT ); Tue, 31 Jul 2012 20:18:45 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:52283 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753970Ab2HAASo (ORCPT ); Tue, 31 Jul 2012 20:18:44 -0400 Date: Tue, 31 Jul 2012 17:18:11 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: Fengguang Wu , Avi Kivity , Steven Rostedt , LKML , "kvm@vger.kernel.org" Subject: Re: Testing tracer wakeup_rt: .. no entries found ..FAILED! Message-ID: <20120801001811.GX2422@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1343663105.3847.7.camel@fedora> <20120731121759.GA17822@localhost> <5017D19B.5080806@redhat.com> <1343738627.27983.30.camel@gandalf.stny.rr.com> <5017D4AB.3090107@redhat.com> <1343740419.27983.33.camel@gandalf.stny.rr.com> <20120731234336.GA5526@localhost> <1343778699.27983.70.camel@gandalf.stny.rr.com> <20120731235705.GW2422@linux.vnet.ibm.com> <1343779778.27983.73.camel@gandalf.stny.rr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1343779778.27983.73.camel@gandalf.stny.rr.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12080100-2398-0000-0000-00000905DD52 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 31, 2012 at 08:09:38PM -0400, Steven Rostedt wrote: > On Tue, 2012-07-31 at 16:57 -0700, Paul E. McKenney wrote: > > > > What was the next lines? I bet you it was "PASSED". Which means it did > > > not fail. This is the second bug you found that has to do with RCU being > > > called in 'idle'. The one that Paul posted a patch for. > > > > Though it needs another patch to actually use it in the right place... > > Right. Something like this: Looks good to me! Thanx, Paul > -- Steve > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 5638104..d915638 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -631,7 +631,12 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) > > memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN); > max_data->pid = tsk->pid; > - max_data->uid = task_uid(tsk); > + /* > + * task_uid() calls rcu_read_lock, but this can be called > + * outside of RCU state monitoring (irq going back to idle). > + */ > + RCU_NONIDLE(max_data->uid = task_uid(tsk)); > + > max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO; > max_data->policy = tsk->policy; > max_data->rt_priority = tsk->rt_priority; > >