Re: [PATCH Resend] cpufreq: Set cpufreq_cpu_data to NULL before putting kobject

[viresh kumar]

On Wednesday 25 February 2015 08:54 AM, Ethan Zhao wrote:
> Viresh,
>   With this patch applied, still got the following warning and panic,
> seems it needs more care.
> 
>      54.474618] ------------[ cut here ]------------
> [   54.545816] WARNING: CPU: 0 PID: 213 at include/linux/kref.h:47
> kobject_get+0x41/0x50()
> [   54.642595] Modules linked in: i2c_i801(+) mfd_core shpchp(+)
> acpi_cpufreq(+) edac_core ioatdma(+) xfs libcrc32c ast syscopyarea ixgbe
> sysfillrect sysimgblt sr_mod sd_mod drm_kms_helper igb mdio cdrom e1000e ahci
> dca ttm libahci uas drm i2c_algo_bit ptp megaraid_sas libata usb_storage
> i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod
> [   55.007264] CPU: 0 PID: 213 Comm: kworker/0:2 Not tainted
> 3.18.5
> [   55.099970] Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER
>    /ASSY,MOTHERBOARD,X4170, BIOS 08120104 05/08/2012
> [   55.239736] Workqueue: kacpi_notify acpi_os_execute_deferred
> [   55.308598]  0000000000000000 00000000bd730b61 ffff88046742baf8
> ffffffff816b7edb
> [   55.398305]  0000000000000000 0000000000000000 ffff88046742bb38
> ffffffff81078ae1
> [   55.488040]  ffff88046742bbd8 ffff8806706b3000 0000000000000292
> 0000000000000000
> [   55.577776] Call Trace:
> [   55.608228]  [<ffffffff816b7edb>] dump_stack+0x46/0x58
> [   55.670895]  [<ffffffff81078ae1>] warn_slowpath_common+0x81/0xa0
> [   55.743952]  [<ffffffff81078bfa>] warn_slowpath_null+0x1a/0x20
> [   55.814929]  [<ffffffff8130d0d1>] kobject_get+0x41/0x50
> [   55.878654]  [<ffffffff8153e955>] cpufreq_cpu_get+0x75/0xc0
> [   55.946528]  [<ffffffff8153f37e>] cpufreq_update_policy+0x2e/0x1f0
> [   56.021682]  [<ffffffff810bf9d2>] ? up+0x32/0x50
> [   56.078126]  [<ffffffff813ab975>] ? acpi_ns_get_node+0xcb/0xf2
> [   56.148974]  [<ffffffff813abdc9>] ? acpi_evaluate_object+0x22c/0x252
> [   56.226066]  [<ffffffff813ac3c2>] ? acpi_get_handle+0x95/0xc0
> [   56.295871]  [<ffffffff8138a7fb>] ? acpi_has_method+0x25/0x40
> [   56.365661]  [<ffffffff813bbcd4>] acpi_processor_ppc_has_changed+0x77/0x82
> [   56.448956]  [<ffffffff8108f726>] ? move_linked_works+0x66/0x90
> [   56.520842]  [<ffffffff813b87b9>] acpi_processor_notify+0x58/0xe7
> [   56.594807]  [<ffffffff8139dfd8>] acpi_ev_notify_dispatch+0x44/0x5c
> [   56.670859]  [<ffffffff81388fe3>] acpi_os_execute_deferred+0x15/0x22
> [   56.747936]  [<ffffffff8109268e>] process_one_work+0x14e/0x3f0
> [   56.818766]  [<ffffffff81092d9b>] worker_thread+0x11b/0x4d0
> [   56.886486]  [<ffffffff81092c80>] ? rescuer_thread+0x350/0x350
> [   56.957316]  [<ffffffff810984f1>] kthread+0xe1/0x100
> [   57.017742]  [<ffffffff81098410>] ? kthread_create_on_node+0x1b0/0x1b0
> [   57.096903]  [<ffffffff816bfe7c>] ret_from_fork+0x7c/0xb0
> [   57.162534]  [<ffffffff81098410>] ? kthread_create_on_node+0x1b0/0x1b0
> [   57.241680] ---[ end trace dce06bb76f547de5 ]---
> 
> 
> Any idea ?

No. Santosh reported this to me few days back, I asked him to perform some
testing but don't know what happened after that..

Can you give me full kernel logs along with the crash after this patch.
You will be required to do some testing this time as I don't have any clue
about the problem..


diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index b4375021238f..230a59d2e0d7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -214,8 +214,10 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
        if (cpufreq_driver) {
                /* get the CPU */
                policy = per_cpu(cpufreq_cpu_data, cpu);
-               if (policy)
+               if (policy) {
                        kobject_get(&policy->kobj);
+                       pr_info("%s: %d", __func__, atomic_read(&policy->kobj.kref.refcount));
+               }
        }

        read_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -233,6 +235,7 @@ void cpufreq_cpu_put(struct cpufreq_policy *policy)
                return;

        kobject_put(&policy->kobj);
+       pr_info("%s: %d", __func__, atomic_read(&policy->kobj.kref.refcount));
        up_read(&cpufreq_rwsem);
 }
 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);

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