From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753478AbcKUJCd (ORCPT ); Mon, 21 Nov 2016 04:02:33 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:38893 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753003AbcKUJCa (ORCPT ); Mon, 21 Nov 2016 04:02:30 -0500 Date: Mon, 21 Nov 2016 01:02:25 -0800 From: "Paul E. McKenney" To: Jiri Olsa Cc: Steven Rostedt , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Josh Triplett , Andi Kleen , Jan Stancek Subject: Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Reply-To: paulmck@linux.vnet.ibm.com References: <20161121005343.GB1891@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161121005343.GB1891@krava> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16112109-0028-0000-0000-0000061317A7 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006115; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000189; SDB=6.00783334; UDB=6.00378275; IPR=6.00560954; BA=6.00004896; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013390; XFM=3.00000011; UTC=2016-11-21 09:02:26 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16112109-0029-0000-0000-00003101F315 Message-Id: <20161121090225.GO3612@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-21_06:,, 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=8.0.1-1609300000 definitions=main-1611210162 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 21, 2016 at 01:53:43AM +0100, Jiri Olsa wrote: > hi, > Jan hit following output when msr tracepoints are enabled on amd server: > > [ 91.585653] =============================== > [ 91.589840] [ INFO: suspicious RCU usage. ] > [ 91.594025] 4.9.0-rc1+ #1 Not tainted > [ 91.597691] ------------------------------- > [ 91.601877] ./arch/x86/include/asm/msr-trace.h:42 suspicious rcu_dereference_check() usage! > [ 91.610222] > [ 91.610222] other info that might help us debug this: > [ 91.610222] > [ 91.618224] > [ 91.618224] RCU used illegally from idle CPU! > [ 91.618224] rcu_scheduler_active = 1, debug_locks = 0 > [ 91.629081] RCU used illegally from extended quiescent state! > [ 91.634820] no locks held by swapper/1/0. > [ 91.638832] > [ 91.638832] stack backtrace: > [ 91.643192] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.0-rc1+ #1 > [ 91.649457] Hardware name: empty empty/S3992, BIOS 'V2.03 ' 05/09/2008 > [ 91.656159] ffffc900018fbdf8 ffffffff813ed43c ffff88017ede8000 0000000000000001 > [ 91.663637] ffffc900018fbe28 ffffffff810fdcd7 ffff880233f95dd0 00000000c0010055 > [ 91.671107] 0000000000000000 0000000000000000 ffffc900018fbe58 ffffffff814297ac > [ 91.678560] Call Trace: > [ 91.681022] [] dump_stack+0x85/0xc9 > [ 91.686164] [] lockdep_rcu_suspicious+0xe7/0x120 > [ 91.692429] [] do_trace_read_msr+0x14c/0x1b0 > [ 91.698349] [] native_read_msr+0x32/0x40 > [ 91.703921] [] amd_e400_idle+0x7e/0x110 > [ 91.709407] [] arch_cpu_idle+0xf/0x20 > [ 91.714720] [] default_idle_call+0x23/0x40 > [ 91.720467] [] cpu_startup_entry+0x1da/0x2b0 > [ 91.726387] [] start_secondary+0x17f/0x1f0 > > > it got away with attached change.. but this rcu logic > is far beyond me, so it's just wild guess.. ;-) If in idle, the _rcuidle() is needed, so: Acked-by: Paul E. McKenney > thanks, > jirka > > > --- > diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c > index d1dee753b949..ca15becea3b6 100644 > --- a/arch/x86/lib/msr.c > +++ b/arch/x86/lib/msr.c > @@ -115,14 +115,14 @@ int msr_clear_bit(u32 msr, u8 bit) > #ifdef CONFIG_TRACEPOINTS > void do_trace_write_msr(unsigned msr, u64 val, int failed) > { > - trace_write_msr(msr, val, failed); > + trace_write_msr_rcuidle(msr, val, failed); > } > EXPORT_SYMBOL(do_trace_write_msr); > EXPORT_TRACEPOINT_SYMBOL(write_msr); > > void do_trace_read_msr(unsigned msr, u64 val, int failed) > { > - trace_read_msr(msr, val, failed); > + trace_read_msr_rcuidle(msr, val, failed); > } > EXPORT_SYMBOL(do_trace_read_msr); > EXPORT_TRACEPOINT_SYMBOL(read_msr); >