Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/14/2012 11:02 AM, Michael Wang wrote:
> On 09/13/2012 06:04 PM, Peter Zijlstra wrote:
>> On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote:
>>> From: Michael Wang
>>>
>>> Fengguang Wu has reported the bug:
>>>
>>> [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002
>>> [0.044017] no locks held by swapper/0/1.
>>> [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9
>>> #34
>>> [0.045861] Call Trace:
>>> [0.048071] [] __schedule_bug+0x5e/0x70
>>> [0.048890] [] __schedule+0x91/0xb10
>>> [0.049660] [] ? vsnprintf+0x33a/0x450
>>> [0.050444] [] ? lg_local_lock+0x6/0x70
>>> [0.051256] [] ? wait_for_xmitr+0x31/0x90
>>> [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0
>>> [0.052903] [] ? _raw_spin_unlock+0x22/0x30
>>> [0.053759] [] ? up+0x1b/0x70
>>> [0.054421] [] __cond_resched+0x1b/0x30
>>> [0.055228] [] _cond_resched+0x45/0x50
>>> [0.056020] [] mutex_lock_nested+0x28/0x370
>>> [0.056884] [] ? console_unlock+0x3a2/0x4e0
>>> [0.057741] [] __irq_alloc_descs+0x39/0x1c0
>>> [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310
>>> [0.060042] [] setup_IO_APIC+0x101/0x744
>>> [0.060878] [] ? clear_IO_APIC+0x31/0x50
>>> [0.061695] [] native_smp_prepare_cpus+0x538/0x680
>>> [0.062644] [] ? do_one_initcall+0x12c/0x12c
>>> [0.063517] [] ? do_one_initcall+0x12c/0x12c
>>> [0.064016] [] kernel_init+0x4b/0x17f
>>> [0.064790] [] ? do_one_initcall+0x12c/0x12c
>>> [0.065660] [] kernel_thread_helper+0x6/0x10
>>>
>>> It was caused by that:
>>>
>>> native_smp_prepare_cpus()
>>> preempt_disable() //preempt_count++
>>> mutex_lock()//in __irq_alloc_descs
>>> __might_sleep() //system is booting, avoid check
>>> might_resched()
>>> __schedule()
>>> preempt_disable() //preempt_count++
>>> schedule_bug() //preempt_count > 1, report bug
>>>
>>> The __might_sleep() avoid check on atomic sleeping until the system booted
>>> while the schedule_bug() doesn't, it's the reason for the bug.
>>>
>>> This patch will add one additional check in schedule_bug() to avoid check
>>> until the system booted, so the check on atomic sleeping will be unified.
>>>
>>> Signed-off-by: Michael Wang
>>> Tested-by: Fengguang Wu
>>> ---
>>> kernel/sched/core.c |3 ++-
>>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>>> index 4376c9f..3396c33 100644
>>> --- a/kernel/sched/core.c
>>> +++ b/kernel/sched/core.c
>>> @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct
>>> *prev)
>>> * schedule() atomically, we ignore that path for now.
>>> * Otherwise, whine if we are scheduling when we should not be.
>>> */
>>> - if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
>>> + if (unlikely(in_atomic_preempt_off() && !prev->exit_state
>>> + && system_state == SYSTEM_RUNNING))
>>> __schedule_bug(prev);
>>> rcu_sleep_check();
>>>
>>
>>
>> No this is very very wrong.. we avoid the might_sleep bug on !
>> SYSTEM_RUNNING because while we _might_ sleep, we should _never_
>> actually sleep under those conditions.
>>
>> So hitting a schedule() here is an actual bug.
>
> I see, so the rule is that we never allowed invoke schedule() with
> preempt disabled.
>
> The actual reason trigger this bug is that:
> we invoke irq_alloc_descs() which will use mutex_lock() while
> !SYSTEM_RUNNING.
> And mutex_lock() invoke the might_sleep(), which do the schedule()
> without any warning.
>
> So if we want to follow the rule, should_resched() should never return
> true if preempt disabled.
>
> I think we could do changes like:
>
>
>
> index c46a011..36fe510 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4209,7 +4209,7 @@ SYSCALL_DEFINE0(sched_yield)
>
> static inline int should_resched(void)
> {
> - return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
> + return need_resched() && !preempt_count();
> }
>
> static void __cond_resched(void)
>
>
>
> Then the should_resched() will return false when the preempt disabled or
> PREEMPT_ACTIVE bit is on.
>
> Could we use this solution?
Let me send out the patch so we could have a thread to discuss, but
please warn me if it's a totally foolish one...
Regards,
Michael Wang
>
> Regards,
> Michael Wang
>
>> --
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>>
>
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Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/14/2012 11:02 AM, Michael Wang wrote:
On 09/13/2012 06:04 PM, Peter Zijlstra wrote:
On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote:
From: Michael Wang wang...@linux.vnet.ibm.com
Fengguang Wu w...@linux.intel.com has reported the bug:
[0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002
[0.044017] no locks held by swapper/0/1.
[0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9
#34
[0.045861] Call Trace:
[0.048071] [c106361e] __schedule_bug+0x5e/0x70
[0.048890] [c1b28701] __schedule+0x91/0xb10
[0.049660] [c14472ea] ? vsnprintf+0x33a/0x450
[0.050444] [c1060006] ? lg_local_lock+0x6/0x70
[0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90
[0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0
[0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30
[0.053759] [c105cdbb] ? up+0x1b/0x70
[0.054421] [c1065d6b] __cond_resched+0x1b/0x30
[0.055228] [c1b292d5] _cond_resched+0x45/0x50
[0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370
[0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0
[0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0
[0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310
[0.060042] [c20638df] setup_IO_APIC+0x101/0x744
[0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50
[0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680
[0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.064016] [c2056adc] kernel_init+0x4b/0x17f
[0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10
It was caused by that:
native_smp_prepare_cpus()
preempt_disable() //preempt_count++
mutex_lock()//in __irq_alloc_descs
__might_sleep() //system is booting, avoid check
might_resched()
__schedule()
preempt_disable() //preempt_count++
schedule_bug() //preempt_count 1, report bug
The __might_sleep() avoid check on atomic sleeping until the system booted
while the schedule_bug() doesn't, it's the reason for the bug.
This patch will add one additional check in schedule_bug() to avoid check
until the system booted, so the check on atomic sleeping will be unified.
Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com
Tested-by: Fengguang Wu w...@linux.intel.com
---
kernel/sched/core.c |3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4376c9f..3396c33 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct
*prev)
* schedule() atomically, we ignore that path for now.
* Otherwise, whine if we are scheduling when we should not be.
*/
- if (unlikely(in_atomic_preempt_off() !prev-exit_state))
+ if (unlikely(in_atomic_preempt_off() !prev-exit_state
+system_state == SYSTEM_RUNNING))
__schedule_bug(prev);
rcu_sleep_check();
No this is very very wrong.. we avoid the might_sleep bug on !
SYSTEM_RUNNING because while we _might_ sleep, we should _never_
actually sleep under those conditions.
So hitting a schedule() here is an actual bug.
I see, so the rule is that we never allowed invoke schedule() with
preempt disabled.
The actual reason trigger this bug is that:
we invoke irq_alloc_descs() which will use mutex_lock() while
!SYSTEM_RUNNING.
And mutex_lock() invoke the might_sleep(), which do the schedule()
without any warning.
So if we want to follow the rule, should_resched() should never return
true if preempt disabled.
I think we could do changes like:
index c46a011..36fe510 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4209,7 +4209,7 @@ SYSCALL_DEFINE0(sched_yield)
static inline int should_resched(void)
{
- return need_resched() !(preempt_count() PREEMPT_ACTIVE);
+ return need_resched() !preempt_count();
}
static void __cond_resched(void)
Then the should_resched() will return false when the preempt disabled or
PREEMPT_ACTIVE bit is on.
Could we use this solution?
Let me send out the patch so we could have a thread to discuss, but
please warn me if it's a totally foolish one...
Regards,
Michael Wang
Regards,
Michael Wang
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Please read the
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/13/2012 06:04 PM, Peter Zijlstra wrote:
> On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote:
>> From: Michael Wang
>>
>> Fengguang Wu has reported the bug:
>>
>> [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002
>> [0.044017] no locks held by swapper/0/1.
>> [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9
>> #34
>> [0.045861] Call Trace:
>> [0.048071] [] __schedule_bug+0x5e/0x70
>> [0.048890] [] __schedule+0x91/0xb10
>> [0.049660] [] ? vsnprintf+0x33a/0x450
>> [0.050444] [] ? lg_local_lock+0x6/0x70
>> [0.051256] [] ? wait_for_xmitr+0x31/0x90
>> [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0
>> [0.052903] [] ? _raw_spin_unlock+0x22/0x30
>> [0.053759] [] ? up+0x1b/0x70
>> [0.054421] [] __cond_resched+0x1b/0x30
>> [0.055228] [] _cond_resched+0x45/0x50
>> [0.056020] [] mutex_lock_nested+0x28/0x370
>> [0.056884] [] ? console_unlock+0x3a2/0x4e0
>> [0.057741] [] __irq_alloc_descs+0x39/0x1c0
>> [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310
>> [0.060042] [] setup_IO_APIC+0x101/0x744
>> [0.060878] [] ? clear_IO_APIC+0x31/0x50
>> [0.061695] [] native_smp_prepare_cpus+0x538/0x680
>> [0.062644] [] ? do_one_initcall+0x12c/0x12c
>> [0.063517] [] ? do_one_initcall+0x12c/0x12c
>> [0.064016] [] kernel_init+0x4b/0x17f
>> [0.064790] [] ? do_one_initcall+0x12c/0x12c
>> [0.065660] [] kernel_thread_helper+0x6/0x10
>>
>> It was caused by that:
>>
>> native_smp_prepare_cpus()
>> preempt_disable() //preempt_count++
>> mutex_lock()//in __irq_alloc_descs
>> __might_sleep() //system is booting, avoid check
>> might_resched()
>> __schedule()
>> preempt_disable() //preempt_count++
>> schedule_bug() //preempt_count > 1, report bug
>>
>> The __might_sleep() avoid check on atomic sleeping until the system booted
>> while the schedule_bug() doesn't, it's the reason for the bug.
>>
>> This patch will add one additional check in schedule_bug() to avoid check
>> until the system booted, so the check on atomic sleeping will be unified.
>>
>> Signed-off-by: Michael Wang
>> Tested-by: Fengguang Wu
>> ---
>> kernel/sched/core.c |3 ++-
>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 4376c9f..3396c33 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct
>> *prev)
>> * schedule() atomically, we ignore that path for now.
>> * Otherwise, whine if we are scheduling when we should not be.
>> */
>> -if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
>> +if (unlikely(in_atomic_preempt_off() && !prev->exit_state
>> +&& system_state == SYSTEM_RUNNING))
>> __schedule_bug(prev);
>> rcu_sleep_check();
>>
>
>
> No this is very very wrong.. we avoid the might_sleep bug on !
> SYSTEM_RUNNING because while we _might_ sleep, we should _never_
> actually sleep under those conditions.
>
> So hitting a schedule() here is an actual bug.
I see, so the rule is that we never allowed invoke schedule() with
preempt disabled.
The actual reason trigger this bug is that:
we invoke irq_alloc_descs() which will use mutex_lock() while
!SYSTEM_RUNNING.
And mutex_lock() invoke the might_sleep(), which do the schedule()
without any warning.
So if we want to follow the rule, should_resched() should never return
true if preempt disabled.
I think we could do changes like:
index c46a011..36fe510 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4209,7 +4209,7 @@ SYSCALL_DEFINE0(sched_yield)
static inline int should_resched(void)
{
- return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
+ return need_resched() && !preempt_count();
}
static void __cond_resched(void)
Then the should_resched() will return false when the preempt disabled or
PREEMPT_ACTIVE bit is on.
Could we use this solution?
Regards,
Michael Wang
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majord...@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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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote: > From: Michael Wang > > Fengguang Wu has reported the bug: > > [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 > [0.044017] no locks held by swapper/0/1. > [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 > #34 > [0.045861] Call Trace: > [0.048071] [] __schedule_bug+0x5e/0x70 > [0.048890] [] __schedule+0x91/0xb10 > [0.049660] [] ? vsnprintf+0x33a/0x450 > [0.050444] [] ? lg_local_lock+0x6/0x70 > [0.051256] [] ? wait_for_xmitr+0x31/0x90 > [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0 > [0.052903] [] ? _raw_spin_unlock+0x22/0x30 > [0.053759] [] ? up+0x1b/0x70 > [0.054421] [] __cond_resched+0x1b/0x30 > [0.055228] [] _cond_resched+0x45/0x50 > [0.056020] [] mutex_lock_nested+0x28/0x370 > [0.056884] [] ? console_unlock+0x3a2/0x4e0 > [0.057741] [] __irq_alloc_descs+0x39/0x1c0 > [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310 > [0.060042] [] setup_IO_APIC+0x101/0x744 > [0.060878] [] ? clear_IO_APIC+0x31/0x50 > [0.061695] [] native_smp_prepare_cpus+0x538/0x680 > [0.062644] [] ? do_one_initcall+0x12c/0x12c > [0.063517] [] ? do_one_initcall+0x12c/0x12c > [0.064016] [] kernel_init+0x4b/0x17f > [0.064790] [] ? do_one_initcall+0x12c/0x12c > [0.065660] [] kernel_thread_helper+0x6/0x10 > > It was caused by that: > > native_smp_prepare_cpus() > preempt_disable() //preempt_count++ > mutex_lock()//in __irq_alloc_descs > __might_sleep() //system is booting, avoid check > might_resched() > __schedule() > preempt_disable() //preempt_count++ > schedule_bug() //preempt_count > 1, report bug > > The __might_sleep() avoid check on atomic sleeping until the system booted > while the schedule_bug() doesn't, it's the reason for the bug. > > This patch will add one additional check in schedule_bug() to avoid check > until the system booted, so the check on atomic sleeping will be unified. > > Signed-off-by: Michael Wang > Tested-by: Fengguang Wu > --- > kernel/sched/core.c |3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 4376c9f..3396c33 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct > *prev) >* schedule() atomically, we ignore that path for now. >* Otherwise, whine if we are scheduling when we should not be. >*/ > - if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) > + if (unlikely(in_atomic_preempt_off() && !prev->exit_state > + && system_state == SYSTEM_RUNNING)) > __schedule_bug(prev); > rcu_sleep_check(); > No this is very very wrong.. we avoid the might_sleep bug on ! SYSTEM_RUNNING because while we _might_ sleep, we should _never_ actually sleep under those conditions. So hitting a schedule() here is an actual bug. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/03/2012 10:16 AM, Michael Wang wrote: > On 08/22/2012 10:40 AM, Michael Wang wrote: >> From: Michael Wang >> >> Fengguang Wu has reported the bug: >> >> [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 >> [0.044017] no locks held by swapper/0/1. >> [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 >> #34 >> [0.045861] Call Trace: >> [0.048071] [] __schedule_bug+0x5e/0x70 >> [0.048890] [] __schedule+0x91/0xb10 >> [0.049660] [] ? vsnprintf+0x33a/0x450 >> [0.050444] [] ? lg_local_lock+0x6/0x70 >> [0.051256] [] ? wait_for_xmitr+0x31/0x90 >> [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0 >> [0.052903] [] ? _raw_spin_unlock+0x22/0x30 >> [0.053759] [] ? up+0x1b/0x70 >> [0.054421] [] __cond_resched+0x1b/0x30 >> [0.055228] [] _cond_resched+0x45/0x50 >> [0.056020] [] mutex_lock_nested+0x28/0x370 >> [0.056884] [] ? console_unlock+0x3a2/0x4e0 >> [0.057741] [] __irq_alloc_descs+0x39/0x1c0 >> [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310 >> [0.060042] [] setup_IO_APIC+0x101/0x744 >> [0.060878] [] ? clear_IO_APIC+0x31/0x50 >> [0.061695] [] native_smp_prepare_cpus+0x538/0x680 >> [0.062644] [] ? do_one_initcall+0x12c/0x12c >> [0.063517] [] ? do_one_initcall+0x12c/0x12c >> [0.064016] [] kernel_init+0x4b/0x17f >> [0.064790] [] ? do_one_initcall+0x12c/0x12c >> [0.065660] [] kernel_thread_helper+0x6/0x10 >> >> It was caused by that: >> >> native_smp_prepare_cpus() >> preempt_disable() //preempt_count++ >> mutex_lock()//in __irq_alloc_descs >> __might_sleep() //system is booting, avoid check >> might_resched() >> __schedule() >> preempt_disable() //preempt_count++ >> schedule_bug() //preempt_count > 1, report bug >> >> The __might_sleep() avoid check on atomic sleeping until the system booted >> while the schedule_bug() doesn't, it's the reason for the bug. >> >> This patch will add one additional check in schedule_bug() to avoid check >> until the system booted, so the check on atomic sleeping will be unified. > > Could I get some comments on this patch? Oh, I just realised I'm using the wrong address... So could I get some comments on the patch? Regards, Michael Wang > > Regards, > Michael Wang >> >> Signed-off-by: Michael Wang >> Tested-by: Fengguang Wu >> --- >> kernel/sched/core.c |3 ++- >> 1 files changed, 2 insertions(+), 1 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 4376c9f..3396c33 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct >> *prev) >> * schedule() atomically, we ignore that path for now. >> * Otherwise, whine if we are scheduling when we should not be. >> */ >> -if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) >> +if (unlikely(in_atomic_preempt_off() && !prev->exit_state >> +&& system_state == SYSTEM_RUNNING)) >> __schedule_bug(prev); >> rcu_sleep_check(); >> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/03/2012 10:16 AM, Michael Wang wrote: On 08/22/2012 10:40 AM, Michael Wang wrote: From: Michael Wang wang...@linux.vnet.ibm.com Fengguang Wu w...@linux.intel.com has reported the bug: [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 [0.044017] no locks held by swapper/0/1. [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [0.045861] Call Trace: [0.048071] [c106361e] __schedule_bug+0x5e/0x70 [0.048890] [c1b28701] __schedule+0x91/0xb10 [0.049660] [c14472ea] ? vsnprintf+0x33a/0x450 [0.050444] [c1060006] ? lg_local_lock+0x6/0x70 [0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90 [0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0 [0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30 [0.053759] [c105cdbb] ? up+0x1b/0x70 [0.054421] [c1065d6b] __cond_resched+0x1b/0x30 [0.055228] [c1b292d5] _cond_resched+0x45/0x50 [0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370 [0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0 [0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0 [0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310 [0.060042] [c20638df] setup_IO_APIC+0x101/0x744 [0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50 [0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680 [0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.064016] [c2056adc] kernel_init+0x4b/0x17f [0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10 It was caused by that: native_smp_prepare_cpus() preempt_disable() //preempt_count++ mutex_lock()//in __irq_alloc_descs __might_sleep() //system is booting, avoid check might_resched() __schedule() preempt_disable() //preempt_count++ schedule_bug() //preempt_count 1, report bug The __might_sleep() avoid check on atomic sleeping until the system booted while the schedule_bug() doesn't, it's the reason for the bug. This patch will add one additional check in schedule_bug() to avoid check until the system booted, so the check on atomic sleeping will be unified. Could I get some comments on this patch? Oh, I just realised I'm using the wrong address... So could I get some comments on the patch? Regards, Michael Wang Regards, Michael Wang Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com Tested-by: Fengguang Wu w...@linux.intel.com --- kernel/sched/core.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4376c9f..3396c33 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct *prev) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ -if (unlikely(in_atomic_preempt_off() !prev-exit_state)) +if (unlikely(in_atomic_preempt_off() !prev-exit_state + system_state == SYSTEM_RUNNING)) __schedule_bug(prev); rcu_sleep_check(); -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote: From: Michael Wang wang...@linux.vnet.ibm.com Fengguang Wu w...@linux.intel.com has reported the bug: [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 [0.044017] no locks held by swapper/0/1. [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [0.045861] Call Trace: [0.048071] [c106361e] __schedule_bug+0x5e/0x70 [0.048890] [c1b28701] __schedule+0x91/0xb10 [0.049660] [c14472ea] ? vsnprintf+0x33a/0x450 [0.050444] [c1060006] ? lg_local_lock+0x6/0x70 [0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90 [0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0 [0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30 [0.053759] [c105cdbb] ? up+0x1b/0x70 [0.054421] [c1065d6b] __cond_resched+0x1b/0x30 [0.055228] [c1b292d5] _cond_resched+0x45/0x50 [0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370 [0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0 [0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0 [0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310 [0.060042] [c20638df] setup_IO_APIC+0x101/0x744 [0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50 [0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680 [0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.064016] [c2056adc] kernel_init+0x4b/0x17f [0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10 It was caused by that: native_smp_prepare_cpus() preempt_disable() //preempt_count++ mutex_lock()//in __irq_alloc_descs __might_sleep() //system is booting, avoid check might_resched() __schedule() preempt_disable() //preempt_count++ schedule_bug() //preempt_count 1, report bug The __might_sleep() avoid check on atomic sleeping until the system booted while the schedule_bug() doesn't, it's the reason for the bug. This patch will add one additional check in schedule_bug() to avoid check until the system booted, so the check on atomic sleeping will be unified. Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com Tested-by: Fengguang Wu w...@linux.intel.com --- kernel/sched/core.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4376c9f..3396c33 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct *prev) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ - if (unlikely(in_atomic_preempt_off() !prev-exit_state)) + if (unlikely(in_atomic_preempt_off() !prev-exit_state + system_state == SYSTEM_RUNNING)) __schedule_bug(prev); rcu_sleep_check(); No this is very very wrong.. we avoid the might_sleep bug on ! SYSTEM_RUNNING because while we _might_ sleep, we should _never_ actually sleep under those conditions. So hitting a schedule() here is an actual bug. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 09/13/2012 06:04 PM, Peter Zijlstra wrote:
On Wed, 2012-08-22 at 10:40 +0800, Michael Wang wrote:
From: Michael Wang wang...@linux.vnet.ibm.com
Fengguang Wu w...@linux.intel.com has reported the bug:
[0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002
[0.044017] no locks held by swapper/0/1.
[0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9
#34
[0.045861] Call Trace:
[0.048071] [c106361e] __schedule_bug+0x5e/0x70
[0.048890] [c1b28701] __schedule+0x91/0xb10
[0.049660] [c14472ea] ? vsnprintf+0x33a/0x450
[0.050444] [c1060006] ? lg_local_lock+0x6/0x70
[0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90
[0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0
[0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30
[0.053759] [c105cdbb] ? up+0x1b/0x70
[0.054421] [c1065d6b] __cond_resched+0x1b/0x30
[0.055228] [c1b292d5] _cond_resched+0x45/0x50
[0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370
[0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0
[0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0
[0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310
[0.060042] [c20638df] setup_IO_APIC+0x101/0x744
[0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50
[0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680
[0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.064016] [c2056adc] kernel_init+0x4b/0x17f
[0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c
[0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10
It was caused by that:
native_smp_prepare_cpus()
preempt_disable() //preempt_count++
mutex_lock()//in __irq_alloc_descs
__might_sleep() //system is booting, avoid check
might_resched()
__schedule()
preempt_disable() //preempt_count++
schedule_bug() //preempt_count 1, report bug
The __might_sleep() avoid check on atomic sleeping until the system booted
while the schedule_bug() doesn't, it's the reason for the bug.
This patch will add one additional check in schedule_bug() to avoid check
until the system booted, so the check on atomic sleeping will be unified.
Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com
Tested-by: Fengguang Wu w...@linux.intel.com
---
kernel/sched/core.c |3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4376c9f..3396c33 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct
*prev)
* schedule() atomically, we ignore that path for now.
* Otherwise, whine if we are scheduling when we should not be.
*/
-if (unlikely(in_atomic_preempt_off() !prev-exit_state))
+if (unlikely(in_atomic_preempt_off() !prev-exit_state
+ system_state == SYSTEM_RUNNING))
__schedule_bug(prev);
rcu_sleep_check();
No this is very very wrong.. we avoid the might_sleep bug on !
SYSTEM_RUNNING because while we _might_ sleep, we should _never_
actually sleep under those conditions.
So hitting a schedule() here is an actual bug.
I see, so the rule is that we never allowed invoke schedule() with
preempt disabled.
The actual reason trigger this bug is that:
we invoke irq_alloc_descs() which will use mutex_lock() while
!SYSTEM_RUNNING.
And mutex_lock() invoke the might_sleep(), which do the schedule()
without any warning.
So if we want to follow the rule, should_resched() should never return
true if preempt disabled.
I think we could do changes like:
index c46a011..36fe510 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4209,7 +4209,7 @@ SYSCALL_DEFINE0(sched_yield)
static inline int should_resched(void)
{
- return need_resched() !(preempt_count() PREEMPT_ACTIVE);
+ return need_resched() !preempt_count();
}
static void __cond_resched(void)
Then the should_resched() will return false when the preempt disabled or
PREEMPT_ACTIVE bit is on.
Could we use this solution?
Regards,
Michael Wang
--
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the body of a message to majord...@vger.kernel.org
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Please read the FAQ at http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 08/22/2012 10:40 AM, Michael Wang wrote: > From: Michael Wang > > Fengguang Wu has reported the bug: > > [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 > [0.044017] no locks held by swapper/0/1. > [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 > #34 > [0.045861] Call Trace: > [0.048071] [] __schedule_bug+0x5e/0x70 > [0.048890] [] __schedule+0x91/0xb10 > [0.049660] [] ? vsnprintf+0x33a/0x450 > [0.050444] [] ? lg_local_lock+0x6/0x70 > [0.051256] [] ? wait_for_xmitr+0x31/0x90 > [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0 > [0.052903] [] ? _raw_spin_unlock+0x22/0x30 > [0.053759] [] ? up+0x1b/0x70 > [0.054421] [] __cond_resched+0x1b/0x30 > [0.055228] [] _cond_resched+0x45/0x50 > [0.056020] [] mutex_lock_nested+0x28/0x370 > [0.056884] [] ? console_unlock+0x3a2/0x4e0 > [0.057741] [] __irq_alloc_descs+0x39/0x1c0 > [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310 > [0.060042] [] setup_IO_APIC+0x101/0x744 > [0.060878] [] ? clear_IO_APIC+0x31/0x50 > [0.061695] [] native_smp_prepare_cpus+0x538/0x680 > [0.062644] [] ? do_one_initcall+0x12c/0x12c > [0.063517] [] ? do_one_initcall+0x12c/0x12c > [0.064016] [] kernel_init+0x4b/0x17f > [0.064790] [] ? do_one_initcall+0x12c/0x12c > [0.065660] [] kernel_thread_helper+0x6/0x10 > > It was caused by that: > > native_smp_prepare_cpus() > preempt_disable() //preempt_count++ > mutex_lock()//in __irq_alloc_descs > __might_sleep() //system is booting, avoid check > might_resched() > __schedule() > preempt_disable() //preempt_count++ > schedule_bug() //preempt_count > 1, report bug > > The __might_sleep() avoid check on atomic sleeping until the system booted > while the schedule_bug() doesn't, it's the reason for the bug. > > This patch will add one additional check in schedule_bug() to avoid check > until the system booted, so the check on atomic sleeping will be unified. Could I get some comments on this patch? Regards, Michael Wang > > Signed-off-by: Michael Wang > Tested-by: Fengguang Wu > --- > kernel/sched/core.c |3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 4376c9f..3396c33 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct > *prev) >* schedule() atomically, we ignore that path for now. >* Otherwise, whine if we are scheduling when we should not be. >*/ > - if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) > + if (unlikely(in_atomic_preempt_off() && !prev->exit_state > + && system_state == SYSTEM_RUNNING)) > __schedule_bug(prev); > rcu_sleep_check(); > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
On 08/22/2012 10:40 AM, Michael Wang wrote: From: Michael Wang wang...@linux.vnet.ibm.com Fengguang Wu w...@linux.intel.com has reported the bug: [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 [0.044017] no locks held by swapper/0/1. [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [0.045861] Call Trace: [0.048071] [c106361e] __schedule_bug+0x5e/0x70 [0.048890] [c1b28701] __schedule+0x91/0xb10 [0.049660] [c14472ea] ? vsnprintf+0x33a/0x450 [0.050444] [c1060006] ? lg_local_lock+0x6/0x70 [0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90 [0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0 [0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30 [0.053759] [c105cdbb] ? up+0x1b/0x70 [0.054421] [c1065d6b] __cond_resched+0x1b/0x30 [0.055228] [c1b292d5] _cond_resched+0x45/0x50 [0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370 [0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0 [0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0 [0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310 [0.060042] [c20638df] setup_IO_APIC+0x101/0x744 [0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50 [0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680 [0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.064016] [c2056adc] kernel_init+0x4b/0x17f [0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10 It was caused by that: native_smp_prepare_cpus() preempt_disable() //preempt_count++ mutex_lock()//in __irq_alloc_descs __might_sleep() //system is booting, avoid check might_resched() __schedule() preempt_disable() //preempt_count++ schedule_bug() //preempt_count 1, report bug The __might_sleep() avoid check on atomic sleeping until the system booted while the schedule_bug() doesn't, it's the reason for the bug. This patch will add one additional check in schedule_bug() to avoid check until the system booted, so the check on atomic sleeping will be unified. Could I get some comments on this patch? Regards, Michael Wang Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com Tested-by: Fengguang Wu w...@linux.intel.com --- kernel/sched/core.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4376c9f..3396c33 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct *prev) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ - if (unlikely(in_atomic_preempt_off() !prev-exit_state)) + if (unlikely(in_atomic_preempt_off() !prev-exit_state + system_state == SYSTEM_RUNNING)) __schedule_bug(prev); rcu_sleep_check(); -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
From: Michael Wang Fengguang Wu has reported the bug: [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 [0.044017] no locks held by swapper/0/1. [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [0.045861] Call Trace: [0.048071] [] __schedule_bug+0x5e/0x70 [0.048890] [] __schedule+0x91/0xb10 [0.049660] [] ? vsnprintf+0x33a/0x450 [0.050444] [] ? lg_local_lock+0x6/0x70 [0.051256] [] ? wait_for_xmitr+0x31/0x90 [0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0 [0.052903] [] ? _raw_spin_unlock+0x22/0x30 [0.053759] [] ? up+0x1b/0x70 [0.054421] [] __cond_resched+0x1b/0x30 [0.055228] [] _cond_resched+0x45/0x50 [0.056020] [] mutex_lock_nested+0x28/0x370 [0.056884] [] ? console_unlock+0x3a2/0x4e0 [0.057741] [] __irq_alloc_descs+0x39/0x1c0 [0.058589] [] io_apic_setup_irq_pin+0x2c/0x310 [0.060042] [] setup_IO_APIC+0x101/0x744 [0.060878] [] ? clear_IO_APIC+0x31/0x50 [0.061695] [] native_smp_prepare_cpus+0x538/0x680 [0.062644] [] ? do_one_initcall+0x12c/0x12c [0.063517] [] ? do_one_initcall+0x12c/0x12c [0.064016] [] kernel_init+0x4b/0x17f [0.064790] [] ? do_one_initcall+0x12c/0x12c [0.065660] [] kernel_thread_helper+0x6/0x10 It was caused by that: native_smp_prepare_cpus() preempt_disable() //preempt_count++ mutex_lock()//in __irq_alloc_descs __might_sleep() //system is booting, avoid check might_resched() __schedule() preempt_disable() //preempt_count++ schedule_bug() //preempt_count > 1, report bug The __might_sleep() avoid check on atomic sleeping until the system booted while the schedule_bug() doesn't, it's the reason for the bug. This patch will add one additional check in schedule_bug() to avoid check until the system booted, so the check on atomic sleeping will be unified. Signed-off-by: Michael Wang Tested-by: Fengguang Wu --- kernel/sched/core.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4376c9f..3396c33 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct *prev) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ - if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) + if (unlikely(in_atomic_preempt_off() && !prev->exit_state + && system_state == SYSTEM_RUNNING)) __schedule_bug(prev); rcu_sleep_check(); -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] sched: unify the check on atomic sleeping in __might_sleep() and schedule_bug()
From: Michael Wang wang...@linux.vnet.ibm.com Fengguang Wu w...@linux.intel.com has reported the bug: [0.043953] BUG: scheduling while atomic: swapper/0/1/0x1002 [0.044017] no locks held by swapper/0/1. [0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [0.045861] Call Trace: [0.048071] [c106361e] __schedule_bug+0x5e/0x70 [0.048890] [c1b28701] __schedule+0x91/0xb10 [0.049660] [c14472ea] ? vsnprintf+0x33a/0x450 [0.050444] [c1060006] ? lg_local_lock+0x6/0x70 [0.051256] [c14fb5b1] ? wait_for_xmitr+0x31/0x90 [0.052019] [c144fd55] ? do_raw_spin_unlock+0xa5/0xf0 [0.052903] [c1b2a532] ? _raw_spin_unlock+0x22/0x30 [0.053759] [c105cdbb] ? up+0x1b/0x70 [0.054421] [c1065d6b] __cond_resched+0x1b/0x30 [0.055228] [c1b292d5] _cond_resched+0x45/0x50 [0.056020] [c1b26c58] mutex_lock_nested+0x28/0x370 [0.056884] [c1034222] ? console_unlock+0x3a2/0x4e0 [0.057741] [c1ac8559] __irq_alloc_descs+0x39/0x1c0 [0.058589] [c10223bc] io_apic_setup_irq_pin+0x2c/0x310 [0.060042] [c20638df] setup_IO_APIC+0x101/0x744 [0.060878] [c1021d51] ? clear_IO_APIC+0x31/0x50 [0.061695] [c20600f4] native_smp_prepare_cpus+0x538/0x680 [0.062644] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.063517] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.064016] [c2056adc] kernel_init+0x4b/0x17f [0.064790] [c2056a91] ? do_one_initcall+0x12c/0x12c [0.065660] [c1b2bbd6] kernel_thread_helper+0x6/0x10 It was caused by that: native_smp_prepare_cpus() preempt_disable() //preempt_count++ mutex_lock()//in __irq_alloc_descs __might_sleep() //system is booting, avoid check might_resched() __schedule() preempt_disable() //preempt_count++ schedule_bug() //preempt_count 1, report bug The __might_sleep() avoid check on atomic sleeping until the system booted while the schedule_bug() doesn't, it's the reason for the bug. This patch will add one additional check in schedule_bug() to avoid check until the system booted, so the check on atomic sleeping will be unified. Signed-off-by: Michael Wang wang...@linux.vnet.ibm.com Tested-by: Fengguang Wu w...@linux.intel.com --- kernel/sched/core.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4376c9f..3396c33 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3321,7 +3321,8 @@ static inline void schedule_debug(struct task_struct *prev) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ - if (unlikely(in_atomic_preempt_off() !prev-exit_state)) + if (unlikely(in_atomic_preempt_off() !prev-exit_state +system_state == SYSTEM_RUNNING)) __schedule_bug(prev); rcu_sleep_check(); -- 1.7.4.1 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
