On 09/26/2012 11:41 AM, Michael Wang wrote:
> On 09/18/2012 11:13 AM, Michael Wang wrote:
>> This patch try to fix the BUG:
>>
>> [ 0.043953] BUG: scheduling while atomic: swapper/0/1/0x10000002
>> [ 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
>>
>> The process to trigger the BUG is:
>>
>> native_smp_prepare_cpus()
>> preempt_disable() //preempt_count++
>> __irq_alloc_descs()
>> mutex_lock()
>> might_sleep() //should_resched() return true
>> __schedule()
>> preempt_disable() //preempt_count++
>> schedule_bug() //preempt_count > 1, report bug
>>
>> So the issue is that should_resched() should not return true while the preempt
>> already disabled.
>
> Hi, Peter
>
> Could we use this solution to fix the bug?
Please tell me if it's wrong, I really want to help fix it.
Regards,
Michael Wang
>
> Regards,
> Michael Wang
>
>>
>> This patch will fix the issue, then might_sleep() won't do schedule in atomic
>> any more.
>>
>> Reported-by: Fengguang Wu <[email protected]>
>> Signed-off-by: Michael Wang <[email protected]>
>> ---
>> kernel/sched/core.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index b38f00e..2b7cd15 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -4171,7 +4171,7 @@ 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)
>>
>
On 10/06/2012 05:06 PM, Michael Wang wrote:
> On 09/26/2012 11:41 AM, Michael Wang wrote:
>> On 09/18/2012 11:13 AM, Michael Wang wrote:
>>> This patch try to fix the BUG:
>>>
>>> [ 0.043953] BUG: scheduling while atomic: swapper/0/1/0x10000002
>>> [ 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
>>>
>>> The process to trigger the BUG is:
>>>
>>> native_smp_prepare_cpus()
>>> preempt_disable() //preempt_count++
>>> __irq_alloc_descs()
>>> mutex_lock()
>>> might_sleep() //should_resched() return true
>>> __schedule()
>>> preempt_disable() //preempt_count++
>>> schedule_bug() //preempt_count > 1, report bug
>>>
>>> So the issue is that should_resched() should not return true while the preempt
>>> already disabled.
>>
>> Hi, Peter
>>
>> Could we use this solution to fix the bug?
>
> Please tell me if it's wrong, I really want to help fix it.
Reset the destination, sorry for the terrible mailing skill...
Regards,
Michael Wang
>
> Regards,
> Michael Wang
>
>>
>> Regards,
>> Michael Wang
>>
>>>
>>> This patch will fix the issue, then might_sleep() won't do schedule in atomic
>>> any more.
>>>
>>> Reported-by: Fengguang Wu <[email protected]>
>>> Signed-off-by: Michael Wang <[email protected]>
>>> ---
>>> kernel/sched/core.c | 2 +-
>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>>> index b38f00e..2b7cd15 100644
>>> --- a/kernel/sched/core.c
>>> +++ b/kernel/sched/core.c
>>> @@ -4171,7 +4171,7 @@ 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)
>>>
>>
>