From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751685AbcAVAee (ORCPT ); Thu, 21 Jan 2016 19:34:34 -0500 Received: from arcturus.aphlor.org ([188.246.204.175]:51290 "EHLO arcturus.aphlor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbcAVAec (ORCPT ); Thu, 21 Jan 2016 19:34:32 -0500 Date: Thu, 21 Jan 2016 19:34:27 -0500 From: Dave Jones To: Linux Kernel Cc: ak@linux.intel.com, x86@kernel.org Subject: suspicious RCU usage in msr tracing. Message-ID: <20160122003427.GA29240@codemonkey.org.uk> Mail-Followup-To: Dave Jones , Linux Kernel , ak@linux.intel.com, x86@kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-Spam-Score: -2.9 (--) X-Spam-Report: Spam detection software, running on the system "arcturus.aphlor.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Just hit this on Linus' current tree. [ INFO: suspicious RCU usage. ] 4.4.0-think+ #1 Tainted: G W ./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage! [...] Content analysis details: (-2.9 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Just hit this on Linus' current tree. [ INFO: suspicious RCU usage. ] 4.4.0-think+ #1 Tainted: G W ------------------------------- ./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/3/0. stack backtrace: CPU: 3 PID: 0 Comm: swapper/3 Tainted: G W 4.4.0-think+ #1 ffffffff8ef82ac0 c4dd1c3486ada576 ffff880468e07f08 ffffffff8e566ae1 ffff880464905340 ffff880468e07f38 ffffffff8e135bf8 ffffffff8f665b00 ffff880464918000 0000000000000000 ffff880464920000 ffff880468e07f70 Call Trace: [] dump_stack+0x4e/0x7d [] lockdep_rcu_suspicious+0xf8/0x110 [] do_trace_write_msr+0x136/0x140 [] native_apic_msr_eoi_write+0x23/0x30 [] smp_call_function_single_interrupt+0x36/0x50 [] smp_call_function_interrupt+0xe/0x10 [] call_function_interrupt+0x90/0xa0 [] ? __asan_store4+0x80/0x80 [] ? poll_idle+0x67/0xc0 [] cpuidle_enter_state+0x174/0x430 [] cpuidle_enter+0x17/0x20 [] cpu_startup_entry+0x4c5/0x5a0 [] ? default_idle_call+0x60/0x60 [] ? clockevents_config_and_register+0x64/0x70 [] start_secondary+0x269/0x300 [] ? set_cpu_sibling_map+0x970/0x970 ------------[ cut here ]------------ 44 DEFINE_EVENT(msr_trace_class, write_msr, 45 TP_PROTO(unsigned msr, u64 val, int failed), 46 TP_ARGS(msr, val, failed) 47 ); Andi, could this be caused by 7f47d8cc039f8746e0038fe05f1ddcb15a2e27f0 ? Dave