From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Brandewie Subject: Re: linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref] Date: Mon, 15 Apr 2013 09:07:10 -0700 Message-ID: <516C25AE.4050503@intel.com> References: <1923819.6Nb81T2TR8@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-pb0-f52.google.com ([209.85.160.52]:42357 "EHLO mail-pb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753541Ab3DOQHO (ORCPT ); Mon, 15 Apr 2013 12:07:14 -0400 In-Reply-To: Sender: linux-next-owner@vger.kernel.org List-ID: To: sedat.dilek@gmail.com Cc: "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 , Nathan Zimmer On 04/13/2013 02:55 AM, Sedat Dilek wrote: > On Sat, Apr 13, 2013 at 12:51 AM, Rafael J. Wysocki wro= te: >> 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 wro= te: >>>>>>>> I found this "[RFC PATCH] kbuild: Build linux-tools package wi= th '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 nam= e : Intel(R) >>>>>>> Core(TM) i7-2640M CPU @ 2.80GHz) and couldn't boot it up. My ub= untu >>>>>>> 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 remov= e/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 m= y 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=3Dlinux-next&id=3De4969ebac83fdea78d89c779331396728a4e619= 9 >>>>>> >>>>> >>>>> 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=E2=94=80=E2=94=90 [pm-next-0= 79576f] Merge branch >>>> 'pm-cpufreq-next' into linux-next >>>> >>>> - Sedat - >>>> >>>> >>>>> - Sedat - >>>>> >>>>> [1] http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.g= it/commit/?h=3Dlinux-next&id=3D5800043b2488a1c4c6e859af860644d37419d58b >>>>> >>>>>>> -- >>>>>>> viresh >>> >>> [ TO Dirk (Author of Intel pstate driver) ] >>> >>> With CONFIG_X86_INTEL_PSTATE=3Dn (unset) I do not see the call-trac= e! >>> >>> My kernel-config and dmesg are attached. >> >> You're seeing a trouble with a new driver, then, so that's not a reg= ression. >> This IS a regression. If the intel_pstate driver is being used __cpufreq_governor() should NO= T 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 hun= k. @@ -1007,9 +1068,12 @@ static int __cpufreq_remove_dev(struct device *d= ev,=20 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 *= dev,=20 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); > > What do you mean by this? > > What are the next steps to get this fixed? > > - Sedat - > >> Thanks for taking the time to debug this! >> >> Rafael >> >> >> -- >> I speak only for myself. >> Rafael J. Wysocki, Intel Open Source Technology Center.