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SubjectRe: linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref]
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 <rjw@sisk.pl>
>>>> wrote:
>>>>> On Friday, April 12, 2013 11:08:37 PM Sedat Dilek wrote:
>>>>>> On Fri, Apr 12, 2013 at 6:27 PM, Sedat Dilek
>>>>>> <sedat.dilek@gmail.com> wrote:
>>>>>>> On Fri, Apr 12, 2013 at 5:45 PM, Sedat Dilek
>>>>>>> <sedat.dilek@gmail.com> wrote:
>>>>>>>> On Fri, Apr 12, 2013 at 4:24 PM, Sedat Dilek
>>>>>>>> <sedat.dilek@gmail.com> wrote:
>>>>>>>>> On Fri, Apr 12, 2013 at 10:23 AM, Viresh Kumar
>>>>>>>>> <viresh.kumar@linaro.org>
>>>>>>>>> wrote:
>>>>>>>>>> On 10 April 2013 11:44, Sedat Dilek <sedat.dilek@gmail.com>
>>>>>>>>>> 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.
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