Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756486Ab3DOSFN (ORCPT ); Mon, 15 Apr 2013 14:05:13 -0400 Received: from relay1.sgi.com ([192.48.179.29]:39460 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754150Ab3DOSFH (ORCPT ); Mon, 15 Apr 2013 14:05:07 -0400 Message-ID: <516C4152.3070601@sgi.com> Date: Mon, 15 Apr 2013 13:05:06 -0500 From: Nathan Zimmer User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Dirk Brandewie CC: , "Rafael J. Wysocki" , Viresh Kumar , Dirk Brandewie , Stephen Rothwell , , , , 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> <516C3BF1.6050902@gmail.com> In-Reply-To: <516C3BF1.6050902@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [128.162.233.145] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6686 Lines: 198 On 04/15/2013 12:42 PM, Dirk Brandewie wrote: > 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 > No worries. I would rather see extra noise from linux-next then extra bugs in the mainline. -- 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/