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| Started by | Leo Yan <leo.yan@linaro.org> |
|---|---|
| First post | 2015-08-25 10:20 +0200 |
| Last post | 2015-08-25 10:40 +0200 |
| Articles | 4 — 3 participants |
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Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed() Leo Yan <leo.yan@linaro.org> - 2015-08-25 10:20 +0200
Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-08-25 10:30 +0200
Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-08-25 10:40 +0200
Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed() Ingo Molnar <mingo@kernel.org> - 2015-08-25 10:40 +0200
| From | Leo Yan <leo.yan@linaro.org> |
|---|---|
| Date | 2015-08-25 10:20 +0200 |
| Subject | Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed() |
| Message-ID | <q1hCx-P0-3@gated-at.bofh.it> |
Hi Wanpeng,
On Tue, Aug 25, 2015 at 03:59:54PM +0800, Wanpeng Li wrote:
> [ 15.273708] ------------[ cut here ]------------
> [ 15.274097] WARNING: CPU: 0 PID: 13 at kernel/sched/core.c:1156 do_set_cpus_allowed+0x7e/0x80()
> [ 15.274857] Modules linked in:
> [ 15.275101] CPU: 0 PID: 13 Comm: migration/0 Not tainted 4.2.0-rc1-00049-g25834c7 #2
> [ 15.275674] 00000000 00000000 d21f1d24 c19228b2 00000000 d21f1d58 c1056a3b c1ba00e4
> [ 15.276084] 00000000 0000000d c1ba17d8 00000484 c10838be 00000484 c10838be d21e5000
> [ 15.276084] d2121900 d21e5158 d21f1d68 c1056b12 00000009 00000000 d21f1d7c c10838be
> [ 15.276084] Call Trace:
> [ 15.276084] [<c19228b2>] dump_stack+0x4b/0x75
> [ 15.276084] [<c1056a3b>] warn_slowpath_common+0x8b/0xc0
> [ 15.276084] [<c10838be>] ? do_set_cpus_allowed+0x7e/0x80
> [ 15.276084] [<c10838be>] ? do_set_cpus_allowed+0x7e/0x80
> [ 15.276084] [<c1056b12>] warn_slowpath_null+0x22/0x30
> [ 15.276084] [<c10838be>] do_set_cpus_allowed+0x7e/0x80
> [ 15.276084] [<c110154c>] cpuset_cpus_allowed_fallback+0x7c/0x170
> [ 15.276084] [<c11014d0>] ? cpuset_cpus_allowed+0x180/0x180
> [ 15.276084] [<c1083ae1>] select_fallback_rq+0x221/0x280
> [ 15.276084] [<c1085073>] migration_call+0xe3/0x250
> [ 15.276084] [<c1079e23>] notifier_call_chain+0x53/0x70
> [ 15.276084] [<c1079e5e>] __raw_notifier_call_chain+0x1e/0x30
> [ 15.276084] [<c1056cc8>] cpu_notify+0x28/0x50
> [ 15.276084] [<c191e4d2>] take_cpu_down+0x22/0x40
> [ 15.276084] [<c1102895>] multi_cpu_stop+0xd5/0x140
> [ 15.276084] [<c11027c0>] ? __stop_cpus+0x80/0x80
> [ 15.276084] [<c11025cc>] cpu_stopper_thread+0xbc/0x170
> [ 15.276084] [<c1085ec9>] ? preempt_count_sub+0x9/0x50
> [ 15.276084] [<c192b6a7>] ? _raw_spin_unlock_irq+0x37/0x50
> [ 15.276084] [<c192b655>] ? _raw_spin_unlock_irqrestore+0x55/0x70
> [ 15.276084] [<c10a9074>] ? trace_hardirqs_on_caller+0x144/0x1e0
> [ 15.276084] [<c11024a5>] ? cpu_stop_should_run+0x35/0x40
> [ 15.276084] [<c1085ec9>] ? preempt_count_sub+0x9/0x50
> [ 15.276084] [<c192b641>] ? _raw_spin_unlock_irqrestore+0x41/0x70
> [ 15.276084] [<c107c944>] smpboot_thread_fn+0x174/0x2f0
> [ 15.276084] [<c107c7d0>] ? sort_range+0x30/0x30
> [ 15.276084] [<c1078934>] kthread+0xc4/0xe0
> [ 15.276084] [<c192c041>] ret_from_kernel_thread+0x21/0x30
> [ 15.276084] [<c1078870>] ? kthread_create_on_node+0x180/0x180
> [ 15.276084] ---[ end trace 15f4c86d404693b0 ]---
>
> After commit (25834c73f93: sched: Fix a race between __kthread_bind()
> and sched_setaffinity()) do_set_cpus_allowed() should be called w/
> p->pi_lock held, however, it is not true in cpuset path currently.
>
> This patch fix it by holding p->pi_lock in cpuset path.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
> kernel/cpuset.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index e414ae9..605ed66 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -2376,8 +2376,12 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
>
> void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
> {
> + unsigned long flags;
> +
> rcu_read_lock();
> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
> do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
Just curious, Will introduce deadlock after acquire lock twice? ;)
Thanks,
Leo Yan
> rcu_read_unlock();
>
> /*
> --
> 1.7.1
>
> --
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> the body of a message to majordomo@vger.kernel.org
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| From | Wanpeng Li <wanpeng.li@hotmail.com> |
|---|---|
| Date | 2015-08-25 10:30 +0200 |
| Message-ID | <q1hMe-10g-9@gated-at.bofh.it> |
| In reply to | #1212787 |
On 8/25/15 4:13 PM, Leo Yan wrote:
> Hi Wanpeng,
>
> On Tue, Aug 25, 2015 at 03:59:54PM +0800, Wanpeng Li wrote:
>> [ 15.273708] ------------[ cut here ]------------
>> [ 15.274097] WARNING: CPU: 0 PID: 13 at kernel/sched/core.c:1156 do_set_cpus_allowed+0x7e/0x80()
>> [ 15.274857] Modules linked in:
>> [ 15.275101] CPU: 0 PID: 13 Comm: migration/0 Not tainted 4.2.0-rc1-00049-g25834c7 #2
>> [ 15.275674] 00000000 00000000 d21f1d24 c19228b2 00000000 d21f1d58 c1056a3b c1ba00e4
>> [ 15.276084] 00000000 0000000d c1ba17d8 00000484 c10838be 00000484 c10838be d21e5000
>> [ 15.276084] d2121900 d21e5158 d21f1d68 c1056b12 00000009 00000000 d21f1d7c c10838be
>> [ 15.276084] Call Trace:
>> [ 15.276084] [<c19228b2>] dump_stack+0x4b/0x75
>> [ 15.276084] [<c1056a3b>] warn_slowpath_common+0x8b/0xc0
>> [ 15.276084] [<c10838be>] ? do_set_cpus_allowed+0x7e/0x80
>> [ 15.276084] [<c10838be>] ? do_set_cpus_allowed+0x7e/0x80
>> [ 15.276084] [<c1056b12>] warn_slowpath_null+0x22/0x30
>> [ 15.276084] [<c10838be>] do_set_cpus_allowed+0x7e/0x80
>> [ 15.276084] [<c110154c>] cpuset_cpus_allowed_fallback+0x7c/0x170
>> [ 15.276084] [<c11014d0>] ? cpuset_cpus_allowed+0x180/0x180
>> [ 15.276084] [<c1083ae1>] select_fallback_rq+0x221/0x280
>> [ 15.276084] [<c1085073>] migration_call+0xe3/0x250
>> [ 15.276084] [<c1079e23>] notifier_call_chain+0x53/0x70
>> [ 15.276084] [<c1079e5e>] __raw_notifier_call_chain+0x1e/0x30
>> [ 15.276084] [<c1056cc8>] cpu_notify+0x28/0x50
>> [ 15.276084] [<c191e4d2>] take_cpu_down+0x22/0x40
>> [ 15.276084] [<c1102895>] multi_cpu_stop+0xd5/0x140
>> [ 15.276084] [<c11027c0>] ? __stop_cpus+0x80/0x80
>> [ 15.276084] [<c11025cc>] cpu_stopper_thread+0xbc/0x170
>> [ 15.276084] [<c1085ec9>] ? preempt_count_sub+0x9/0x50
>> [ 15.276084] [<c192b6a7>] ? _raw_spin_unlock_irq+0x37/0x50
>> [ 15.276084] [<c192b655>] ? _raw_spin_unlock_irqrestore+0x55/0x70
>> [ 15.276084] [<c10a9074>] ? trace_hardirqs_on_caller+0x144/0x1e0
>> [ 15.276084] [<c11024a5>] ? cpu_stop_should_run+0x35/0x40
>> [ 15.276084] [<c1085ec9>] ? preempt_count_sub+0x9/0x50
>> [ 15.276084] [<c192b641>] ? _raw_spin_unlock_irqrestore+0x41/0x70
>> [ 15.276084] [<c107c944>] smpboot_thread_fn+0x174/0x2f0
>> [ 15.276084] [<c107c7d0>] ? sort_range+0x30/0x30
>> [ 15.276084] [<c1078934>] kthread+0xc4/0xe0
>> [ 15.276084] [<c192c041>] ret_from_kernel_thread+0x21/0x30
>> [ 15.276084] [<c1078870>] ? kthread_create_on_node+0x180/0x180
>> [ 15.276084] ---[ end trace 15f4c86d404693b0 ]---
>>
>> After commit (25834c73f93: sched: Fix a race between __kthread_bind()
>> and sched_setaffinity()) do_set_cpus_allowed() should be called w/
>> p->pi_lock held, however, it is not true in cpuset path currently.
>>
>> This patch fix it by holding p->pi_lock in cpuset path.
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>> ---
>> kernel/cpuset.c | 4 ++++
>> 1 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
>> index e414ae9..605ed66 100644
>> --- a/kernel/cpuset.c
>> +++ b/kernel/cpuset.c
>> @@ -2376,8 +2376,12 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
>>
>> void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
>> {
>> + unsigned long flags;
>> +
>> rcu_read_lock();
>> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
>> do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
>> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
> Just curious, Will introduce deadlock after acquire lock twice? ;)
Could you point out where acquires lock twice?
Regards,
Wanpeng Li
>
> Thanks,
> Leo Yan
>
>> rcu_read_unlock();
>>
>> /*
>> --
>> 1.7.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at http://www.tux.org/lkml/
> --
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> the body of a message to majordomo@vger.kernel.org
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| From | Wanpeng Li <wanpeng.li@hotmail.com> |
|---|---|
| Date | 2015-08-25 10:40 +0200 |
| Message-ID | <q1hVV-1br-19@gated-at.bofh.it> |
| In reply to | #1212814 |
On 8/25/15 4:30 PM, Ingo Molnar wrote:
> * Wanpeng Li <wanpeng.li@hotmail.com> wrote:
>
>>>> --- a/kernel/cpuset.c
>>>> +++ b/kernel/cpuset.c
>>>> @@ -2376,8 +2376,12 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
>>>> void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
>>>> {
>>>> + unsigned long flags;
>>>> +
>>>> rcu_read_lock();
>>>> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
>>>> do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
>>>> + raw_spin_lock_irqsave(&tsk->pi_lock, flags);
>>> Just curious, Will introduce deadlock after acquire lock twice? ;)
>> Could you point out where acquires lock twice?
> In the code you quote?
Shame me, sorry for sending out the wrong version. I fix in it soon in v2.
Regards,
Wanpeng Li
>
> Thanks,
>
> Ingo
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| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2015-08-25 10:40 +0200 |
| Message-ID | <q1hVV-1br-21@gated-at.bofh.it> |
| In reply to | #1212814 |
* Wanpeng Li <wanpeng.li@hotmail.com> wrote:
> >>--- a/kernel/cpuset.c
> >>+++ b/kernel/cpuset.c
> >>@@ -2376,8 +2376,12 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
> >> void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
> >> {
> >>+ unsigned long flags;
> >>+
> >> rcu_read_lock();
> >>+ raw_spin_lock_irqsave(&tsk->pi_lock, flags);
> >> do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
> >>+ raw_spin_lock_irqsave(&tsk->pi_lock, flags);
> >Just curious, Will introduce deadlock after acquire lock twice? ;)
>
> Could you point out where acquires lock twice?
In the code you quote?
Thanks,
Ingo
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