On Thu, Aug 5, 2021 at 9:35 AM Viresh Kumar viresh.kumar@linaro.org wrote:

On 05-08-21, 15:29, Kevin Hao wrote:

...

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: stable@vger.kernel.org Signed-off-by: Kevin Hao haokexin@gmail.com

---

v2: Introduce sugov_clear_global_tunables() as suggested by Rafael.

kernel/sched/cpufreq_schedutil.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 57124614363d..e7af18857371 100644 --- 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_tunables_alloc(struct sugov_policy *sg_polic 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 @@ static int sugov_init(struct cpufreq_policy *policy) 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_policy *policy) 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);
  

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

Applied as 5.15 material.

However, since I'm on vacation next week, it will show up in linux-next after -rc6.

Thanks!