On 08/13/2014 03:39 AM, Viresh Kumar wrote:
> On 12 August 2014 17:03, Prarit Bhargava <pra...@redhat.com> wrote:
>> Okay, this is what I have and I can reproduce this *easily* 100% of the time.
>>
>> I've used your above config options and have enabled LOCKDEP.
>>
>> In order to restore the locking, I've applied the following patch to the
>> cpufreq
>> core (sorry for the cut-and-paste):
>>
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index d9fdedd..dfda238 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -2192,9 +2192,7 @@ static int cpufreq_set_policy(struct cpufreq_policy
>> *polic
>> /* end old governor */
>> if (old_gov) {
>> __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
>> - up_write(&policy->rwsem);
>> __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
>> - down_write(&policy->rwsem);
>> }
>>
>> /* start new governor */
>> @@ -2203,9 +2201,7 @@ static int cpufreq_set_policy(struct cpufreq_policy
>> *polic
>> if (!__cpufreq_governor(policy, CPUFREQ_GOV_START))
>> goto out;
>>
>> - up_write(&policy->rwsem);
>> __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
>> - down_write(&policy->rwsem);
>> }
>>
>> /* new governor failed, so re-start old one */
>>
>>
>> I've modified the acpi-cpufreq driver to include (sorry for the
>> cut-and-paste)
>>
>> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
>> index b0c18ed..97653c3 100644
>> --- a/drivers/cpufreq/acpi-cpufreq.c
>> +++ b/drivers/cpufreq/acpi-cpufreq.c
>> @@ -884,6 +884,9 @@ static struct freq_attr *acpi_cpufreq_attr[] = {
>> };
>>
>> static struct cpufreq_driver acpi_cpufreq_driver = {
>> + .flags = CPUFREQ_STICKY |
>> + CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
>> + CPUFREQ_NEED_INITIAL_FREQ_CHECK,
>> .verify = cpufreq_generic_frequency_table_verify,
>> .target_index = acpi_cpufreq_target,
>> .bios_limit = acpi_processor_get_bios_limit,
>>
>> I do a
>>
>> cat /sys/devices/system/cpu/cpu2/cpufreq/conservative/*
>> echo ondemand > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor
>>
>> and then I immediately see the stack trace.
>
> What's your system configuration? How many clusters/cpus/etc..
Anywhere from 2-4 sockets, 8 - 240 cpus (depending on # of sockets), x86 arch.
P.
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
