From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932400AbbFQAlw (ORCPT ); Tue, 16 Jun 2015 20:41:52 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:39426 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932353AbbFQAlb (ORCPT ); Tue, 16 Jun 2015 20:41:31 -0400 Message-ID: <5580C239.4060707@codeaurora.org> Date: Tue, 16 Jun 2015 17:41:29 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com, John Stultz CC: Nicolas Pitre , Steven Rostedt , lkml Subject: Re: Suspicious RCU usage at boot w/ arm ipi trace events? References: <20150617003154.GV3913@linux.vnet.ibm.com> In-Reply-To: <20150617003154.GV3913@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/16/2015 05:31 PM, Paul E. McKenney wrote: > On Tue, Jun 16, 2015 at 05:21:59PM -0700, John Stultz wrote: >> Not sure if I have the right folks on CC. Noticed this booting on a >> apq8064 based system w/ 4.1-rc7 (plus a few patches that I believe are >> unrelated). >> >> >> [ 0.008796] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000 >> [ 0.009024] Setting up static identity map for 0x80208280 - 0x802082d8 >> [ 0.084781] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001 >> [ 0.085119] >> [ 0.085139] =============================== >> [ 0.085152] [ INFO: suspicious RCU usage. ] >> [ 0.085168] 4.1.0-rc7-00033-gb5bed2f #153 Not tainted >> [ 0.085180] ------------------------------- >> [ 0.085195] include/trace/events/ipi.h:68 suspicious >> rcu_dereference_check() usage! >> [ 0.085205] >> [ 0.085205] other info that might help us debug this: >> [ 0.085205] >> [ 0.085220] >> [ 0.085220] RCU used illegally from idle CPU! >> [ 0.085220] rcu_scheduler_active = 1, debug_locks = 0 >> [ 0.085235] RCU used illegally from extended quiescent state! >> [ 0.085247] no locks held by swapper/0/0. >> [ 0.085256] >> [ 0.085256] stack backtrace: >> [ 0.085275] CPU: 0 PID: 0 Comm: swapper/0 Not tainted >> 4.1.0-rc7-00033-gb5bed2f #153 >> [ 0.085288] Hardware name: Qualcomm (Flattened Device Tree) >> [ 0.085323] [] (unwind_backtrace) from [] >> (show_stack+0x10/0x14) >> [ 0.085348] [] (show_stack) from [] >> (dump_stack+0x70/0xbc) >> [ 0.085369] [] (dump_stack) from [] >> (handle_IPI+0x428/0x604) >> [ 0.085393] [] (handle_IPI) from [] >> (gic_handle_irq+0x54/0x5c) >> [ 0.085423] [] (gic_handle_irq) from [] >> (__irq_svc+0x44/0x7c) >> [ 0.085436] Exception stack(0xc09f3f48 to 0xc09f3f90) >> [ 0.085451] 3f40: 00000001 00000001 00000000 >> c09f73b8 c09f4528 c0a5de9c >> [ 0.085468] 3f60: c076b4f0 00000000 00000000 c09ef108 c0a5cec1 >> 00000001 00000000 c09f3f90 >> [ 0.085481] 3f80: c026bf60 c0210ab8 20000113 ffffffff >> [ 0.085512] [] (__irq_svc) from [] >> (arch_cpu_idle+0x20/0x3c) >> [ 0.085549] [] (arch_cpu_idle) from [] >> (cpu_startup_entry+0x2c0/0x5dc) >> [ 0.085576] [] (cpu_startup_entry) from [] >> (start_kernel+0x358/0x3c4) >> [ 0.085600] [] (start_kernel) from [<8020807c>] (0x8020807c) >> >> >> Let me know if there's any patches you'd like me to test, or if you'd >> like config details. > At first glance, looks like a failure to invoke irq_enter() from > __irq_svc(), gic_handle_irq(), or handle_IPI(). > > Thanx, Paul > The tracepoint 'trace_ipi_entry' in handle_IPI() is using RCU and we haven't called irq_enter() yet at the point. Does this tracepoint need to have _rcuidle() added to it? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project