From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleksandr Natalenko Subject: Re: [BUG] oops in cpufreq driver with AMD Kaveri CPU Date: Tue, 12 Aug 2014 21:04:30 +0300 Message-ID: <1449757.YVvGmvgCpE@spock> References: <4708675.eITUXPv8Ih@spock> <97078cc7-f961-4575-ab72-ec88e6f30b9e@email.android.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from natalenko.name ([78.47.77.148]:58310 "EHLO natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753529AbaHLSEe (ORCPT ); Tue, 12 Aug 2014 14:04:34 -0400 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: "linux-kernel@vger.kernel.org" , Linux PM list Well, I've added the following code to cpufreq_register_notifier() (drivers/cpufreq/cpufreq.c) to CPUFREQ_TRANSITION_NOTIFIER case: === pr_info("Registered transition notifier: %p, (%p)\n", nb->notifier_call, &nb- >notifier_call); === And got the following in my dmesg (only 1 line): === $ cat /var/log/kern.log | grep "Registered transition notifier" Aug 12 17:23:45 defiant kernel: [ 3.084977] cpufreq: Registered transition notifier: ffffffff81590378, (ffffffff81cb0ba0) === System.map tells me, that ffffffff81590378 corresponds to cpufreq_stat_notifier_trans() (in drivers/cpufreq/cpufreq_stats.c). Also I've added === pr_info("%s\n", __func__); === to all callbacks (hello, LXR :)), and got the following occurrences in dmesg: === $ cat /var/log/kern.log | egrep -e '(acpi_|cpufreq|notifier)' | awk '{print($7)}' | sort -u acpi_processor_ppc_notifier acpi_thermal_cpufreq_notifier cpufreq_stat_notifier_policy === No extra notifiers are involved so far, but also I haven't caught new hang yet as it occurs randomly. Still waiting for it, but I hope my little investigation could help somehow. On Tuesday 12 August 2014 13:16:25 Viresh Kumar wrote: > On Tue, Aug 12, 2014 at 12:56 PM, Oleksandr Natalenko > > wrote: > > Got that and will try to investigate ASAP. > > > > Just to note: I tried to use powersave governor and got the same result. I > > believe notifiers are used with powersave governor as well. Am I wrong? > Notifiers are used from the cpufreq core when frequency is changed. > And the powersave governor should have changed the frequency only > ONCE, i.e. to go to lowest frequency. > > So, it probably happened at the first & only change at that time as well.. > But it shouldn't happen any later. So, see what the log looks like on > that crash. -- Oleksandr post-factum Natalenko, MSc pf-kernel community https://natalenko.name/