From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756537Ab2GaX5V (ORCPT ); Tue, 31 Jul 2012 19:57:21 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:39301 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754721Ab2GaX5U (ORCPT ); Tue, 31 Jul 2012 19:57:20 -0400 Date: Tue, 31 Jul 2012 16:57:06 -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: <20120731235705.GW2422@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120724090330.GA9830@localhost> <20120724090720.GA10434@localhost> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1343778699.27983.70.camel@gandalf.stny.rr.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12073123-2398-0000-0000-00000905C173 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 31, 2012 at 07:51:39PM -0400, Steven Rostedt wrote: > On Wed, 2012-08-01 at 07:43 +0800, Fengguang Wu wrote: > > On Tue, Jul 31, 2012 at 09:13:39AM -0400, Steven Rostedt wrote: > > > On Tue, 2012-07-31 at 15:50 +0300, Avi Kivity wrote: > > > > On 07/31/2012 03:43 PM, Steven Rostedt wrote: > > > > > > > That would be better. A hypervisor might be real-time capable (with > > > > some effort kvm can do this), so we don't want to turn off real time > > > > features just based on that. > > > > > > It would only turn off if you enable selftests and the timing falied. If > > > the kvm had real time features, this most likely would fail anyway. But > > > that said, here's a patch that should solve this: > > > > No luck.. it still fails: > > I bet you it didn't ;-) > > > > > [ 2.360068] Testing tracer irqsoff: [ 2.854529] > > [ 2.854828] =============================== > > [ 2.855560] [ INFO: suspicious RCU usage. ] > > [ 2.856266] 3.5.0-00024-g01ff5db-dirty #3 Not tainted > > [ 2.857182] ------------------------------- > > [ 2.857933] /c/wfg/linux/include/linux/rcupdate.h:730 rcu_read_lock() used illegally while idle! > > [ 2.859450] > > [ 2.859450] other info that might help us debug this: > > [ 2.859450] > > [ 2.860874] > > [ 2.860874] RCU used illegally from idle CPU! > > [ 2.860874] rcu_scheduler_active = 1, debug_locks = 0 > > [ 2.862754] RCU used illegally from extended quiescent state! > > [ 2.863741] 2 locks held by swapper/0/0: > > > > [ 2.864377] #0: [ 2.864423] (max_trace_lock){......}, at: [<814f6bfe>] check_critical_timing+0xd7/0x286 > > [ 2.864423] #1: (rcu_read_lock){.+.+..}, at: [<8116f930>] __update_max_tr+0x0/0x430 > > > > [ 2.864423] stack backtrace: > > [ 2.864423] Pid: 0, comm: swapper/0 Not tainted 3.5.0-00024-g01ff5db-dirty #3 > > [ 2.864423] Call Trace: > > [ 2.864423] [<81103a06>] lockdep_rcu_suspicious+0x1c6/0x210 > > [ 2.864423] [<8116fc9a>] __update_max_tr+0x36a/0x430 > > [ 2.864423] [<8116f930>] ? tracing_record_cmdline+0x200/0x200 > > [ 2.864423] [<8117186e>] update_max_tr_single+0x14e/0x2c0 > > [ 2.864423] [<81170baa>] ? __trace_stack+0x2a/0x40 > > [ 2.864423] [<814f6d22>] check_critical_timing+0x1fb/0x286 > > [ 2.864423] [<81013313>] ? default_idle+0x593/0xc30 > > [ 2.864423] [<81013313>] ? default_idle+0x593/0xc30 > > [ 2.864423] [<8110a0e7>] ? trace_hardirqs_on+0x27/0x40 > > [ 2.864423] [<8117ea5e>] time_hardirqs_on+0x1de/0x220 > > [ 2.864423] [<81013313>] ? default_idle+0x593/0xc30 > > [ 2.864423] [<81109d6d>] trace_hardirqs_on_caller+0x2d/0x380 > > [ 2.864423] [<8110a0e7>] trace_hardirqs_on+0x27/0x40 > > [ 2.864423] [<81013313>] default_idle+0x593/0xc30 > > [ 2.864423] [<8101692d>] cpu_idle+0x2dd/0x390 > > [ 2.864423] [<814eb841>] rest_init+0x2f5/0x314 > > [ 2.864423] [<814eb54c>] ? __read_lock_failed+0x14/0x14 > > [ 2.864423] [<817a43b4>] start_kernel+0x866/0x87a > > 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... Thanx, Paul