From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nathan Zimmer Subject: Re: linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref] Date: Mon, 15 Apr 2013 12:27:04 -0500 Message-ID: <516C3868.40903@sgi.com> References: <1923819.6Nb81T2TR8@vostro.rjw.lan> <516C25AE.4050503@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <516C25AE.4050503@intel.com> Sender: linux-pm-owner@vger.kernel.org To: Dirk Brandewie Cc: sedat.dilek@gmail.com, "Rafael J. Wysocki" , Viresh Kumar , Dirk Brandewie , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, Linux PM list , Lists linaro-kernel List-Id: linux-next.vger.kernel.org On 04/15/2013 11:07 AM, Dirk Brandewie wrote: > On 04/13/2013 02:55 AM, Sedat Dilek wrote: >> On Sat, Apr 13, 2013 at 12:51 AM, Rafael J. Wysocki wr= ote: >>> On Friday, April 12, 2013 11:08:37 PM Sedat Dilek wrote: >>>> On Fri, Apr 12, 2013 at 6:27 PM, Sedat Dilek=20 >>>> wrote: >>>>> On Fri, Apr 12, 2013 at 5:45 PM, Sedat Dilek=20 >>>>> wrote: >>>>>> On Fri, Apr 12, 2013 at 4:24 PM, Sedat Dilek=20 >>>>>> wrote: >>>>>>> On Fri, Apr 12, 2013 at 10:23 AM, Viresh Kumar=20 >>>>>>> wrote: >>>>>>>> On 10 April 2013 11:44, Sedat Dilek wr= ote: >>>>>>>>> I found this "[RFC PATCH] kbuild: Build linux-tools package=20 >>>>>>>>> with 'make >>>>>>>>> deb-pkg'" from February 2012. >>>>>>>>> Can't say what happened to it... >>>>>>>> >>>>>>>> Sedat, >>>>>>>> >>>>>>>> Sorry for being late. I am down with Fever and throat infectio= n=20 >>>>>>>> since few days. >>>>>>>> Still struggling with it.. >>>>>>>> >>>>>>>> There are few things i tried. Firstly the tag: next-20130326 i= s=20 >>>>>>>> bad as there are >>>>>>>> some bad commits in cpufreq core in it. >>>>>>>> >>>>>>>> I then tried latest linux-next/master on my Thinkpad (model=20 >>>>>>>> name : Intel(R) >>>>>>>> Core(TM) i7-2640M CPU @ 2.80GHz) and couldn't boot it up. My=20 >>>>>>>> ubuntu >>>>>>>> just hanged. >>>>>>>> >>>>>>>> Then i tried Rafael's linux-next branch >>>>>>>> >>>>>>>> 079576f Merge branch 'pm-cpufreq-next' into linux-next >>>>>>>> >>>>>>>> And couldn't find any issues with it. I am easily able to=20 >>>>>>>> remove/add cpus at >>>>>>>> runtime.. >>>>>>>> >>>>>>>> Can you give this branch a try? >>>>>>>> >>>>>>> >>>>>>> OK, you seem to be well again, nice to hear. >>>>>>> >>>>>>> I was doing the whole week spring-cleaning in the apartment of=20 >>>>>>> my parents. >>>>>>> Now, I have some minutes for a compilation run. >>>>>>> >>>>>>> I guess "cpufreq: Call __cpufreq_governor() with correct=20 >>>>>>> policy->cpus >>>>>>> mask" could be the correct fix, but will try the GIT branch you= =20 >>>>>>> have >>>>>>> mentioned. >>>>>>> >>>>>>> - Sedat - >>>>>>> >>>>>>> [1]=20 >>>>>>> http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git= /commit/?h=3Dlinux-next&id=3De4969ebac83fdea78d89c779331396728a4e6199 >>>>>>> >>>>>> >>>>>> Both BROKEN here, specific pm-next commitid and pulling >>>>>> pm.git#linux-next into next-20130411 (see attached files). >>>>>> >>>>>> Is "cpufreq: convert cpufreq_driver to using RCU" the root cause= =20 >>>>>> of this all? >>>>>> >>>>> >>>>> [ CC Nathan ] >>>>> >>>>> NO, wrong assumption. >>>>> >>>>> 2013-04-12 18:04 Sedat Dilek o [revert-cpufreq-rcu] Revert >>>>> "cpufreq: convert cpufreq_driver to using RCU" >>>>> 2013-04-12 18:04 Sedat Dilek o Revert "cpufreq: Call >>>>> __cpufreq_governor() with correct policy->cpus mask" >>>>> 2013-04-11 23:24 Rafael J. Wysocki M=E2=94=80=E2=94=90 [pm-next-= 079576f] Merge=20 >>>>> branch >>>>> 'pm-cpufreq-next' into linux-next >>>>> >>>>> - Sedat - >>>>> >>>>> >>>>>> - Sedat - >>>>>> >>>>>> [1]=20 >>>>>> http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/= commit/?h=3Dlinux-next&id=3D5800043b2488a1c4c6e859af860644d37419d58b >>>>>> >>>>>>>> --=20 >>>>>>>> viresh >>>> >>>> [ TO Dirk (Author of Intel pstate driver) ] >>>> >>>> With CONFIG_X86_INTEL_PSTATE=3Dn (unset) I do not see the call-tra= ce! >>>> >>>> My kernel-config and dmesg are attached. >>> >>> You're seeing a trouble with a new driver, then, so that's not a=20 >>> regression. >>> > > This IS a regression. > > If the intel_pstate driver is being used __cpufreq_governor() should=20 > NOT be > called intel_pstate does not implement the target() callback. > > Nathan's commit 5800043b2 changed the fence around the call to > __cpufreq_governor() in __cpufreq_remove_dev() here is the relevant h= unk. > > @@ -1007,9 +1068,12 @@ static int __cpufreq_remove_dev(struct device=20 > *dev, struct subsys_interface *sif > unsigned int cpu =3D dev->id, ret, cpus; > unsigned long flags; > struct cpufreq_policy *data; > + struct cpufreq_driver *driver; > struct kobject *kobj; > struct completion *cmp; > struct device *cpu_dev; > + bool has_target; > + int (*exit)(struct cpufreq_policy *policy); > > pr_debug("%s: unregistering CPU %u\n", __func__, cpu); > > @@ -1025,14 +1089,19 @@ static int __cpufreq_remove_dev(struct device= =20 > *dev, struct subsys_interface *sif > return -EINVAL; > } > > - if (cpufreq_driver->target) > + rcu_read_lock(); > + driver =3D rcu_dereference(cpufreq_driver); > + has_target =3D driver->target ? true : false; > + exit =3D driver->exit; > + if (has_target) > __cpufreq_governor(data, CPUFREQ_GOV_STOP); > > #ifdef CONFIG_HOTPLUG_CPU > - if (!cpufreq_driver->setpolicy) > + if (!driver->setpolicy) > strncpy(per_cpu(cpufreq_cpu_governor, cpu), > data->governor->name, CPUFREQ_NAME_LEN); > #endif > + rcu_read_unlock(); > > WARN_ON(lock_policy_rwsem_write(cpu)); > cpus =3D cpumask_weight(data->cpus); > I am not clear at what is at issue. Are you saying __cpufreq_governor=20 can change the value of cpufreq_driver->target? I hadn't thought that=20 was allowed but if it is the code would need to be fixed. Nate