Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640Ab3FYWaP (ORCPT ); Tue, 25 Jun 2013 18:30:15 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:50890 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146Ab3FYWaN (ORCPT ); Tue, 25 Jun 2013 18:30:13 -0400 From: "Rafael J. Wysocki" To: Tim Gardner Cc: Jacob Shin , Viresh Kumar , LKML , cpufreq@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: od_set_powersave_bias: NULL pointer dereference Date: Wed, 26 Jun 2013 00:39:38 +0200 Message-ID: <1516594.2Op2Cie0Tj@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.10.0-rc5+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <51C9E443.8070100@canonical.com> References: <51C87ADC.4070409@canonical.com> <20130625161935.GA10208@jshin-Toonie> <51C9E443.8070100@canonical.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3818 Lines: 111 On Tuesday, June 25, 2013 12:41:07 PM Tim Gardner wrote: > On 06/25/2013 10:19 AM, Jacob Shin wrote: > > On Tue, Jun 25, 2013 at 12:26:14PM +0530, Viresh Kumar wrote: > >> On 24 June 2013 22:29, Tim Gardner wrote: > >>> This is from Ubuntu Saucy based on 3.10-rc7: > >>> > >>> [ 12.911676] BUG: unable to handle kernel NULL pointer dereference at > >>> 0000000000000070 > >>> [ 12.911691] IP: [] od_set_powersave_bias+0x92/0xc0 > >>> > >> > >> Can you please look into this bug? It occurred after your > >> patch... This is the boot log crash we have: > > > > Hi, > > > > Yes, so sorry about that, it looks like I failed to test with: > > > > CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y > > CONFIG_CPU_FREQ_GOV_PERFORMANCE=y > > CONFIG_CPU_FREQ_GOV_ONDEMAND=y > > CONFIG_X86_AMD_FREQ_SENSITIVITY=m > > > > The following patch fixes this, Tim, could you please test ? : > > > > ---8<--- > > > > From 3c727b1f775448599e67c5fb2121d79448e80c90 Mon Sep 17 00:00:00 2001 > > From: Jacob Shin > > Date: Tue, 25 Jun 2013 10:40:54 -0500 > > Subject: [PATCH 1/1] cpufreq: fix NULL pointer deference at > > od_set_powersave_bias() > > > > When initializing the default powersave_bias value, we need to first > > make sure that this policy is running the ondemand governor. > > > > Reported-by: Tim Gardner > > Signed-off-by: Jacob Shin > > --- > > drivers/cpufreq/cpufreq_ondemand.c | 17 +++++++++++++---- > > 1 file changed, 13 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c > > index 4b9bb5d..93eb5cb 100644 > > --- a/drivers/cpufreq/cpufreq_ondemand.c > > +++ b/drivers/cpufreq/cpufreq_ondemand.c > > @@ -47,6 +47,8 @@ static struct od_ops od_ops; > > static struct cpufreq_governor cpufreq_gov_ondemand; > > #endif > > > > +static unsigned int default_powersave_bias; > > + > > static void ondemand_powersave_bias_init_cpu(int cpu) > > { > > struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu); > > @@ -543,7 +545,7 @@ static int od_init(struct dbs_data *dbs_data) > > > > tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; > > tuners->ignore_nice = 0; > > - tuners->powersave_bias = 0; > > + tuners->powersave_bias = default_powersave_bias; > > tuners->io_is_busy = should_io_be_busy(); > > > > dbs_data->tuners = tuners; > > @@ -585,6 +587,7 @@ static void od_set_powersave_bias(unsigned int powersave_bias) > > unsigned int cpu; > > cpumask_t done; > > > > + default_powersave_bias = powersave_bias; > > cpumask_clear(&done); > > > > get_online_cpus(); > > @@ -593,11 +596,17 @@ static void od_set_powersave_bias(unsigned int powersave_bias) > > continue; > > > > policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy; > > - dbs_data = policy->governor_data; > > - od_tuners = dbs_data->tuners; > > - od_tuners->powersave_bias = powersave_bias; > > + if (!policy) > > + continue; > > > > cpumask_or(&done, &done, policy->cpus); > > + > > + if (policy->governor != &cpufreq_gov_ondemand) > > + continue; > > + > > + dbs_data = policy->governor_data; > > + od_tuners = dbs_data->tuners; > > + od_tuners->powersave_bias = default_powersave_bias; > > } > > put_online_cpus(); > > } > > > > That appears to have done the trick. You can add my Tested-by. Queued up as an urgent fix. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/