[PATCH 5.14 046/432] cpufreq: schedutil: Use kobject release() method to free sugov_tunables

Greg Kroah-Hartman
2021-09-16T17:14:51Z

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
@@ -537,9 +537,17 @@ 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 *********************/
@@ -639,12 +647,10 @@ 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)
@@ -707,7 +713,7 @@ 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);
@@ -734,7 +740,7 @@ 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);