From: Dirk Brandewie <dirk.brandewie@gmail.com>
To: sedat.dilek@gmail.com
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
Viresh Kumar <viresh.kumar@linaro.org>,
Dirk Brandewie <dirk.j.brandewie@intel.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
cpufreq@vger.kernel.org, Linux PM list <linux-pm@vger.kernel.org>,
Lists linaro-kernel <linaro-kernel@lists.linaro.org>,
Nathan Zimmer <nzimmer@sgi.com>
Subject: Re: linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref]
Date: Mon, 15 Apr 2013 09:07:10 -0700 [thread overview]
Message-ID: <516C25AE.4050503@intel.com> (raw)
In-Reply-To: <CA+icZUXUGOjGUAFxgQk0780pcBB-YjiujDLXF+gJFegi+pd+dA@mail.gmail.com>
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);
>
> 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.
next prev parent reply other threads:[~2013-04-15 16:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+icZUU_K9PiFMqMsOEk1+c2DX8LrUojZptPiRVarv4dcB2qFA@mail.gmail.com>
2013-04-09 14:03 ` linux-next: Tree for Apr 9 [cpufreq: NULL pointer deref] Rafael J. Wysocki
2013-04-09 14:04 ` Sedat Dilek
2013-04-09 14:56 ` Viresh Kumar
2013-04-09 14:59 ` Sedat Dilek
2013-04-09 16:08 ` Sedat Dilek
2013-04-09 16:51 ` Viresh Kumar
2013-04-09 16:57 ` Sedat Dilek
2013-04-09 18:26 ` Sedat Dilek
2013-04-09 18:29 ` Sedat Dilek
2013-04-09 18:39 ` Sedat Dilek
2013-04-09 20:26 ` Sedat Dilek
2013-04-10 5:41 ` Sedat Dilek
2013-04-10 5:53 ` Sedat Dilek
2013-04-10 6:14 ` Sedat Dilek
2013-04-12 8:23 ` Viresh Kumar
2013-04-12 14:24 ` Sedat Dilek
2013-04-12 15:45 ` Sedat Dilek
2013-04-12 16:27 ` Sedat Dilek
2013-04-12 21:08 ` Sedat Dilek
2013-04-12 22:51 ` Rafael J. Wysocki
2013-04-13 9:55 ` Sedat Dilek
2013-04-15 16:07 ` Dirk Brandewie [this message]
2013-04-15 16:13 ` Sedat Dilek
2013-04-15 17:22 ` Viresh Kumar
2013-04-15 17:51 ` Sedat Dilek
2013-04-15 17:57 ` Sedat Dilek
2013-04-15 18:07 ` Sedat Dilek
2013-04-15 18:01 ` Dirk Brandewie
2013-04-17 14:04 ` Sedat Dilek
2013-04-17 16:14 ` Rafael J. Wysocki
2013-04-21 23:30 ` Rafael J. Wysocki
2013-04-22 3:14 ` Viresh Kumar
2013-04-22 12:00 ` Rafael J. Wysocki
2013-04-15 17:27 ` Nathan Zimmer
2013-04-15 17:42 ` Dirk Brandewie
2013-04-15 18:05 ` Nathan Zimmer
2013-04-09 14:59 ` Viresh Kumar
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