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Message-ID: <YUPB2HlDaoLfNrQ2@sashalap>
Date: Thu, 16 Sep 2021 18:14:48 -0400
From: Sasha Levin <sashal@...nel.org>
To: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, stable@...r.kernel.org,
Kevin Hao <haokexin@...il.com>,
Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH 5.13 039/380] cpufreq: schedutil: Use kobject release()
method to free sugov_tunables
On Thu, Sep 16, 2021 at 06:55:49PM +0200, Rafael J. Wysocki wrote:
>On 9/16/2021 5:56 PM, Greg Kroah-Hartman wrote:
>>From: Kevin Hao <haokexin@...il.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@...r.kernel.org> # 4.7+
>>Signed-off-by: Kevin Hao <haokexin@...il.com>
>>Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
>>Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>>Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
>>@@ -536,9 +536,17 @@ 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 *********************/
>>@@ -638,12 +646,10 @@ 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)
>>@@ -706,7 +712,7 @@ 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);
>>@@ -733,7 +739,7 @@ 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 adding this one.
I'll drop, let us know when to bring it back.
--
Thanks,
Sasha
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