Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755790Ab3DORmP (ORCPT ); Mon, 15 Apr 2013 13:42:15 -0400 Received: from mail-da0-f52.google.com ([209.85.210.52]:62574 "EHLO mail-da0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751410Ab3DORmN (ORCPT ); Mon, 15 Apr 2013 13:42:13 -0400 Message-ID: <516C3BF1.6050902@gmail.com> Date: Mon, 15 Apr 2013 10:42:09 -0700 From: Dirk Brandewie User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Nathan Zimmer CC: Dirk Brandewie , 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 Subject: Re: linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref] References: <1923819.6Nb81T2TR8@vostro.rjw.lan> <516C25AE.4050503@intel.com> <516C3868.40903@sgi.com> In-Reply-To: <516C3868.40903@sgi.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6139 Lines: 166 On 04/15/2013 10:27 AM, Nathan Zimmer wrote: > 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 wrote: >>>> On Friday, April 12, 2013 11:08:37 PM Sedat Dilek wrote: >>>>> On Fri, Apr 12, 2013 at 6:27 PM, Sedat Dilek wrote: >>>>>> On Fri, Apr 12, 2013 at 5:45 PM, Sedat Dilek wrote: >>>>>>> On Fri, Apr 12, 2013 at 4:24 PM, Sedat Dilek wrote: >>>>>>>> On Fri, Apr 12, 2013 at 10:23 AM, Viresh Kumar >>>>>>>> wrote: >>>>>>>>> On 10 April 2013 11:44, Sedat Dilek wrote: >>>>>>>>>> I found this "[RFC PATCH] kbuild: Build linux-tools package 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 infection since >>>>>>>>> few days. >>>>>>>>> Still struggling with it.. >>>>>>>>> >>>>>>>>> There are few things i tried. Firstly the tag: next-20130326 is bad as >>>>>>>>> there are >>>>>>>>> some bad commits in cpufreq core in it. >>>>>>>>> >>>>>>>>> I then tried latest linux-next/master on my Thinkpad (model name >>>>>>>>> : Intel(R) >>>>>>>>> Core(TM) i7-2640M CPU @ 2.80GHz) and couldn't boot it up. My 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 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 my parents. >>>>>>>> Now, I have some minutes for a compilation run. >>>>>>>> >>>>>>>> I guess "cpufreq: Call __cpufreq_governor() with correct policy->cpus >>>>>>>> mask" could be the correct fix, but will try the GIT branch you have >>>>>>>> mentioned. >>>>>>>> >>>>>>>> - Sedat - >>>>>>>> >>>>>>>> [1] >>>>>>>> http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=e4969ebac83fdea78d89c779331396728a4e6199 >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> 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 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─┐ [pm-next-079576f] Merge branch >>>>>> 'pm-cpufreq-next' into linux-next >>>>>> >>>>>> - Sedat - >>>>>> >>>>>> >>>>>>> - Sedat - >>>>>>> >>>>>>> [1] >>>>>>> http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=5800043b2488a1c4c6e859af860644d37419d58b >>>>>>> >>>>>>> >>>>>>>>> -- >>>>>>>>> viresh >>>>> >>>>> [ TO Dirk (Author of Intel pstate driver) ] >>>>> >>>>> With CONFIG_X86_INTEL_PSTATE=n (unset) I do not see the call-trace! >>>>> >>>>> My kernel-config and dmesg are attached. >>>> >>>> You're seeing a trouble with a new driver, then, so that's not a regression. >>>> >> >> This IS a regression. >> >> If the intel_pstate driver is being used __cpufreq_governor() should 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 hunk. >> >> @@ -1007,9 +1068,12 @@ static int __cpufreq_remove_dev(struct device *dev, >> struct subsys_interface *sif >> unsigned int cpu = 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 *dev, >> struct subsys_interface *sif >> return -EINVAL; >> } >> >> - if (cpufreq_driver->target) >> + rcu_read_lock(); >> + driver = rcu_dereference(cpufreq_driver); >> + has_target = driver->target ? true : false; >> + exit = 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 = cpumask_weight(data->cpus); >> > > I am not clear at what is at issue. Are you saying __cpufreq_governor can > change the value of cpufreq_driver->target? I hadn't thought that was allowed > but if it is the code would need to be fixed. > Sorry I think pointing to your patch may have red herring see viresh's mail. The issue is that __cpufreq_governor() is being called when intel_pstate is the scaling driver intel_pstate does not implement ->target(). From the stack trace it looked like this was happening in __cpufreq_remove_dev() so I "assumed" it was the first instance of the target fence that was failing. I am rebuilding using the next tree with viresh's patch I will let you know what I find sorry for the noise. --Dirk > Nate -- 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/