From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752343AbdBOSCF (ORCPT ); Wed, 15 Feb 2017 13:02:05 -0500 Received: from muru.com ([72.249.23.125]:35300 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750719AbdBOSCE (ORCPT ); Wed, 15 Feb 2017 13:02:04 -0500 Date: Wed, 15 Feb 2017 10:01:58 -0800 From: Tony Lindgren To: Sergey Senozhatsky Cc: Petr Mladek , Steven Rostedt , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org, Sergey Senozhatsky , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, Russell King Subject: Re: Regression in next with use printk_safe buffers in printk Message-ID: <20170215180158.GO21809@atomide.com> References: <20170213185956.GM3897@atomide.com> <20170214160140.GA401@tigerII.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170214160140.GA401@tigerII.localdomain> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, * Sergey Senozhatsky [170214 08:03]: > Hello, > > Cc Rafael, just in case Found another issue on booting ARM devices, so adding Russell too. > On (02/13/17 10:59), Tony Lindgren wrote: > > Looks like commit f975237b7682 ("printk: use printk_safe buffers in > > printk") causes "possible circular locking dependency detected " for > > me on the first suspend. > > thanks for the report. > > > Reverting the following four patches in next makes it go away: > > > > d9c23523ed98 ("printk: drop call_console_drivers() unused param") > > de6fcbdb68b2 ("printk: convert the rest to printk-safe") > > 8b1742c9c207 ("printk: remove zap_locks() function") > > f975237b7682 ("printk: use printk_safe buffers in printk") > > > these patches basically just enable locked where it previously was > forcibly turned off. no timekeeping/pm/sched/etc code was modified. Below is another issue I noticed caused by commit f975237b7682 that I noticed during booting. Regards, Tony 8< -------------------------- [ 2.581939] hw-breakpoint: Failed to enable monitor mode on CPU 0. [ 2.591613] hw-breakpoint: CPU 0 failed to disable vector catch [ 2.597686] [ 2.597717] =============================== [ 2.597717] [ ERR: suspicious RCU usage. ] [ 2.597717] 4.10.0-rc8-next-20170215+ #119 Not tainted [ 2.597717] ------------------------------- [ 2.597717] ./include/trace/events/printk.h:32 suspicious rcu_dereference_check() usage! [ 2.597717] [ 2.597717] other info that might help us debug this: [ 2.597717] [ 2.597717] [ 2.597717] RCU used illegally from idle CPU! [ 2.597717] rcu_scheduler_active = 2, debug_locks = 0 [ 2.597747] RCU used illegally from extended quiescent state! [ 2.597747] 2 locks held by swapper/0/0: [ 2.597747] #0: (cpu_pm_notifier_lock){......}, at: [] cpu_pm_exit+0x10/0x54 [ 2.597747] #1: (console_lock){+.+.+.}, at: [] vprintk_emit+0x264/0x474 [ 2.597747] [ 2.597747] stack backtrace: [ 2.597778] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.10.0-rc8-next-20170215+ #119 [ 2.597778] Hardware name: Generic OMAP4 (Flattened Device Tree) [ 2.597778] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 2.597778] [] (show_stack) from [] (dump_stack+0xac/0xe0) [ 2.597778] [] (dump_stack) from [] (console_unlock+0x5e8/0x650) [ 2.597778] [] (console_unlock) from [] (vprintk_emit+0x270/0x474) [ 2.597778] [] (vprintk_emit) from [] (vprintk_default+0x20/0x28) [ 2.597808] [] (vprintk_default) from [] (printk+0x20/0x30) [ 2.597808] [] (printk) from [] (reset_ctrl_regs+0x108/0x288) [ 2.597808] [] (reset_ctrl_regs) from [] (dbg_cpu_pm_notify+0x28/0x30) [ 2.597808] [] (dbg_cpu_pm_notify) from [] (notifier_call_chain+0x44/0x80) [ 2.597808] [] (notifier_call_chain) from [] (cpu_pm_exit+0x2c/0x54) [ 2.597808] [] (cpu_pm_exit) from [] (omap_enter_idle_coupled+0x80/0x208) [ 2.597808] [] (omap_enter_idle_coupled) from [] (cpuidle_enter_state+0x118/0x4ac) [ 2.597808] [] (cpuidle_enter_state) from [] (cpuidle_enter_state_coupled+0x3a8/0x40c) [ 2.597839] [] (cpuidle_enter_state_coupled) from [] (do_idle+0x1a4/0x218) [ 2.597839] [] (do_idle) from [] (cpu_startup_entry+0x18/0x1c) [ 2.597839] [] (cpu_startup_entry) from [] (start_kernel+0x35c/0x3d4) [ 2.597839] [] (start_kernel) from [<8000807c>] (0x8000807c)