diff mbox series

[5.10,033/306] cpufreq: schedutil: Use kobject release() method to free sugov_tunables

Message ID 20210916155755.075805845@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Sept. 16, 2021, 3:56 p.m. UTC 
From: Kevin Hao <haokexin@gmail.com>

commit e5c6b312ce3cc97e90ea159446e6bfa06645364d upstream.

The struct sugov_tunables is protected by the kobject, so we can't free
it directly. Otherwise we would get a call trace like this:
  ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x30
  WARNING: CPU: 3 PID: 720 at lib/debugobjects.c:505 debug_print_object+0xb8/0x100
  Modules linked in:
  CPU: 3 PID: 720 Comm: a.sh Tainted: G        W         5.14.0-rc1-next-20210715-yocto-standard+ #507
  Hardware name: Marvell OcteonTX CN96XX board (DT)
  pstate: 40400009 (nZcv daif +PAN -UAO -TCO BTYPE=--)
  pc : debug_print_object+0xb8/0x100
  lr : debug_print_object+0xb8/0x100
  sp : ffff80001ecaf910
  x29: ffff80001ecaf910 x28: ffff00011b10b8d0 x27: ffff800011043d80
  x26: ffff00011a8f0000 x25: ffff800013cb3ff0 x24: 0000000000000000
  x23: ffff80001142aa68 x22: ffff800011043d80 x21: ffff00010de46f20
  x20: ffff800013c0c520 x19: ffff800011d8f5b0 x18: 0000000000000010
  x17: 6e6968207473696c x16: 5f72656d6974203a x15: 6570797420746365
  x14: 6a626f2029302065 x13: 303378302f307830 x12: 2b6e665f72656d69
  x11: ffff8000124b1560 x10: ffff800012331520 x9 : ffff8000100ca6b0
  x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 0000000000000001
  x5 : ffff800011d8c000 x4 : ffff800011d8c740 x3 : 0000000000000000
  x2 : ffff0001108301c0 x1 : ab3c90eedf9c0f00 x0 : 0000000000000000
  Call trace:
   debug_print_object+0xb8/0x100
   __debug_check_no_obj_freed+0x1c0/0x230
   debug_check_no_obj_freed+0x20/0x88
   slab_free_freelist_hook+0x154/0x1c8
   kfree+0x114/0x5d0
   sugov_exit+0xbc/0xc0
   cpufreq_exit_governor+0x44/0x90
   cpufreq_set_policy+0x268/0x4a8
   store_scaling_governor+0xe0/0x128
   store+0xc0/0xf0
   sysfs_kf_write+0x54/0x80
   kernfs_fop_write_iter+0x128/0x1c0
   new_sync_write+0xf0/0x190
   vfs_write+0x2d4/0x478
   ksys_write+0x74/0x100
   __arm64_sys_write+0x24/0x30
   invoke_syscall.constprop.0+0x54/0xe0
   do_el0_svc+0x64/0x158
   el0_svc+0x2c/0xb0
   el0t_64_sync_handler+0xb0/0xb8
   el0t_64_sync+0x198/0x19c
  irq event stamp: 5518
  hardirqs last  enabled at (5517): [<ffff8000100cbd7c>] console_unlock+0x554/0x6c8
  hardirqs last disabled at (5518): [<ffff800010fc0638>] el1_dbg+0x28/0xa0
  softirqs last  enabled at (5504): [<ffff8000100106e0>] __do_softirq+0x4d0/0x6c0
  softirqs last disabled at (5483): [<ffff800010049548>] irq_exit+0x1b0/0x1b8

So split the original sugov_tunables_free() into two functions,
sugov_clear_global_tunables() is just used to clear the global_tunables
and the new sugov_tunables_free() is used as kobj_type::release to
release the sugov_tunables safely.

Fixes: 9bdcb44e391d ("cpufreq: schedutil: New governor based on scheduler utilization data")
Cc: 4.7+ <stable@vger.kernel.org> # 4.7+
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/sched/cpufreq_schedutil.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

Comments

Alexey Khoroshilov Sept. 19, 2021, 6:36 p.m. UTC | #1 
On 16.09.2021 20:20, Greg Kroah-Hartman wrote:
> On Thu, Sep 16, 2021 at 06:12:44PM +0200, Rafael J. Wysocki wrote:

>> On 9/16/2021 5:56 PM, Greg Kroah-Hartman wrote:

>>> From: Kevin Hao <haokexin@gmail.com>

>>>

>>> commit e5c6b312ce3cc97e90ea159446e6bfa06645364d upstream.

>>>

>>> The struct sugov_tunables is protected by the kobject, so we can't free

>>> it directly. Otherwise we would get a call trace like this:

>>>    ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x30

>>>    WARNING: CPU: 3 PID: 720 at lib/debugobjects.c:505 debug_print_object+0xb8/0x100

>>>    Modules linked in:

>>>    CPU: 3 PID: 720 Comm: a.sh Tainted: G        W         5.14.0-rc1-next-20210715-yocto-standard+ #507

>>>    Hardware name: Marvell OcteonTX CN96XX board (DT)

>>>    pstate: 40400009 (nZcv daif +PAN -UAO -TCO BTYPE=--)

>>>    pc : debug_print_object+0xb8/0x100

>>>    lr : debug_print_object+0xb8/0x100

>>>    sp : ffff80001ecaf910

>>>    x29: ffff80001ecaf910 x28: ffff00011b10b8d0 x27: ffff800011043d80

>>>    x26: ffff00011a8f0000 x25: ffff800013cb3ff0 x24: 0000000000000000

>>>    x23: ffff80001142aa68 x22: ffff800011043d80 x21: ffff00010de46f20

>>>    x20: ffff800013c0c520 x19: ffff800011d8f5b0 x18: 0000000000000010

>>>    x17: 6e6968207473696c x16: 5f72656d6974203a x15: 6570797420746365

>>>    x14: 6a626f2029302065 x13: 303378302f307830 x12: 2b6e665f72656d69

>>>    x11: ffff8000124b1560 x10: ffff800012331520 x9 : ffff8000100ca6b0

>>>    x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 0000000000000001

>>>    x5 : ffff800011d8c000 x4 : ffff800011d8c740 x3 : 0000000000000000

>>>    x2 : ffff0001108301c0 x1 : ab3c90eedf9c0f00 x0 : 0000000000000000

>>>    Call trace:

>>>     debug_print_object+0xb8/0x100

>>>     __debug_check_no_obj_freed+0x1c0/0x230

>>>     debug_check_no_obj_freed+0x20/0x88

>>>     slab_free_freelist_hook+0x154/0x1c8

>>>     kfree+0x114/0x5d0

>>>     sugov_exit+0xbc/0xc0

>>>     cpufreq_exit_governor+0x44/0x90

>>>     cpufreq_set_policy+0x268/0x4a8

>>>     store_scaling_governor+0xe0/0x128

>>>     store+0xc0/0xf0

>>>     sysfs_kf_write+0x54/0x80

>>>     kernfs_fop_write_iter+0x128/0x1c0

>>>     new_sync_write+0xf0/0x190

>>>     vfs_write+0x2d4/0x478

>>>     ksys_write+0x74/0x100

>>>     __arm64_sys_write+0x24/0x30

>>>     invoke_syscall.constprop.0+0x54/0xe0

>>>     do_el0_svc+0x64/0x158

>>>     el0_svc+0x2c/0xb0

>>>     el0t_64_sync_handler+0xb0/0xb8

>>>     el0t_64_sync+0x198/0x19c

>>>    irq event stamp: 5518

>>>    hardirqs last  enabled at (5517): [<ffff8000100cbd7c>] console_unlock+0x554/0x6c8

>>>    hardirqs last disabled at (5518): [<ffff800010fc0638>] el1_dbg+0x28/0xa0

>>>    softirqs last  enabled at (5504): [<ffff8000100106e0>] __do_softirq+0x4d0/0x6c0

>>>    softirqs last disabled at (5483): [<ffff800010049548>] irq_exit+0x1b0/0x1b8

>>>

>>> So split the original sugov_tunables_free() into two functions,

>>> sugov_clear_global_tunables() is just used to clear the global_tunables

>>> and the new sugov_tunables_free() is used as kobj_type::release to

>>> release the sugov_tunables safely.

>>>

>>> Fixes: 9bdcb44e391d ("cpufreq: schedutil: New governor based on scheduler utilization data")

>>> Cc: 4.7+ <stable@vger.kernel.org> # 4.7+

>>> Signed-off-by: Kevin Hao <haokexin@gmail.com>

>>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

>>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

>>> ---

>>>   kernel/sched/cpufreq_schedutil.c |   16 +++++++++++-----

>>>   1 file changed, 11 insertions(+), 5 deletions(-)

>>>

>>> --- a/kernel/sched/cpufreq_schedutil.c

>>> +++ b/kernel/sched/cpufreq_schedutil.c

>>> @@ -610,9 +610,17 @@ static struct attribute *sugov_attrs[] =

>>>   };

>>>   ATTRIBUTE_GROUPS(sugov);

>>> +static void sugov_tunables_free(struct kobject *kobj)

>>> +{

>>> +	struct gov_attr_set *attr_set = container_of(kobj, struct gov_attr_set, kobj);

>>> +

>>> +	kfree(to_sugov_tunables(attr_set));

>>> +}

>>> +

>>>   static struct kobj_type sugov_tunables_ktype = {

>>>   	.default_groups = sugov_groups,

>>>   	.sysfs_ops = &governor_sysfs_ops,

>>> +	.release = &sugov_tunables_free,

>>>   };

>>>   /********************** cpufreq governor interface *********************/

>>> @@ -712,12 +720,10 @@ static struct sugov_tunables *sugov_tuna

>>>   	return tunables;

>>>   }

>>> -static void sugov_tunables_free(struct sugov_tunables *tunables)

>>> +static void sugov_clear_global_tunables(void)

>>>   {

>>>   	if (!have_governor_per_policy())

>>>   		global_tunables = NULL;

>>> -

>>> -	kfree(tunables);

>>>   }

>>>   static int sugov_init(struct cpufreq_policy *policy)

>>> @@ -780,7 +786,7 @@ out:

>>>   fail:

>>>   	kobject_put(&tunables->attr_set.kobj);

>>>   	policy->governor_data = NULL;

>>> -	sugov_tunables_free(tunables);

>>> +	sugov_clear_global_tunables();

>>>   stop_kthread:

>>>   	sugov_kthread_stop(sg_policy);

>>> @@ -807,7 +813,7 @@ static void sugov_exit(struct cpufreq_po

>>>   	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);

>>>   	policy->governor_data = NULL;

>>>   	if (!count)

>>> -		sugov_tunables_free(tunables);

>>> +		sugov_clear_global_tunables();

>>>   	mutex_unlock(&global_tunables_lock);

>>>

>>>

>> Please defer this one.

>>

>> It uncovers a bug in cpufreq that needs to be fixed separately.

> 

> Now dropped from all queues, thanks!

> 

> greg k-h

> 


Hi Greg,

I am trying to get familiar with stable release process, because we
would like to start testing stable release candidates. But I cannot get
all the nuances how to get automatically information regarding rc code
ready to be tested.

Also I wonder how we could automatically detect situations when stable
release is expected to became diverged from the rc, e.g. like
[PATCH 5.10 033/306] cpufreq: schedutil: Use kobject release() method to
free sugov_tunables
was dropped from 5.10.67 without announcing the 5.10.67-rc2?

Any suggestions are appreciated.

Best regards,
Alexey Khoroshilov,
Linux Verification Center, ISPRAS
Greg Kroah-Hartman Sept. 20, 2021, 5 a.m. UTC | #2 
On Sun, Sep 19, 2021 at 09:36:20PM +0300, Alexey Khoroshilov wrote:
> Hi Greg,

> 

> I am trying to get familiar with stable release process, because we

> would like to start testing stable release candidates. But I cannot get

> all the nuances how to get automatically information regarding rc code

> ready to be tested.


You might want to start a new thread and not bury it down in a response
to a specific commit in order to make sure that people see it.

What specifically have you tried that did not work for detecting the -rc
releases?

> Also I wonder how we could automatically detect situations when stable

> release is expected to became diverged from the rc, e.g. like

> [PATCH 5.10 033/306] cpufreq: schedutil: Use kobject release() method to

> free sugov_tunables

> was dropped from 5.10.67 without announcing the 5.10.67-rc2?


Look at the stable queue tree, that has all of the information in it,
right?

thanks,

greg k-h
diff mbox series

Patch

--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -610,9 +610,17 @@  static struct attribute *sugov_attrs[] =
 };
 ATTRIBUTE_GROUPS(sugov);
 
+static void sugov_tunables_free(struct kobject *kobj)
+{
+	struct gov_attr_set *attr_set = container_of(kobj, struct gov_attr_set, kobj);
+
+	kfree(to_sugov_tunables(attr_set));
+}
+
 static struct kobj_type sugov_tunables_ktype = {
 	.default_groups = sugov_groups,
 	.sysfs_ops = &governor_sysfs_ops,
+	.release = &sugov_tunables_free,
 };
 
 /********************** cpufreq governor interface *********************/
@@ -712,12 +720,10 @@  static struct sugov_tunables *sugov_tuna
 	return tunables;
 }
 
-static void sugov_tunables_free(struct sugov_tunables *tunables)
+static void sugov_clear_global_tunables(void)
 {
 	if (!have_governor_per_policy())
 		global_tunables = NULL;
-
-	kfree(tunables);
 }
 
 static int sugov_init(struct cpufreq_policy *policy)
@@ -780,7 +786,7 @@  out:
 fail:
 	kobject_put(&tunables->attr_set.kobj);
 	policy->governor_data = NULL;
-	sugov_tunables_free(tunables);
+	sugov_clear_global_tunables();
 
 stop_kthread:
 	sugov_kthread_stop(sg_policy);
@@ -807,7 +813,7 @@  static void sugov_exit(struct cpufreq_po
 	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 	policy->governor_data = NULL;
 	if (!count)
-		sugov_tunables_free(tunables);
+		sugov_clear_global_tunables();
 
 	mutex_unlock(&global_tunables_lock);