Re: [BUG][PPC64] BUG in 2.6.26.5-rt9 causing Hang

[Gregory Haskins]

Gregory Haskins wrote:
> Hi Chirag
>
> Chirag Jog wrote:
>   
>> Hi Gregory,
>> We see the following BUG followed by a hang on the latest kernel 2.6.26.5-rt9 on a Power6 blade (PPC64)
>> It is easily recreated by running the async_handler or sbrk_mutex (realtime tests from ltp) tests.
>>   
>>     
>
> Call me an LTP newbie, but where can I get the sbrk_mutex/async_handler
> tests.
Ok, I figured out this part.  I needed a newer version of the .rpm from
a different repo.  However, both async_handler and sbrk_mutex seem to
segfault for me.  Hmm

---

ghaskins@test:~> uname -a
Linux test 2.6.26.5-rt9-rt #1 SMP PREEMPT RT Mon Sep 29 14:26:45 EDT
2008 x86_64 x86_64 x86_64 GNU/Linux

test:/home/ghaskins #
/usr/lib64/ltp/testcases/realtime/func/async_handler/async_handler

-----------------------------------
Asynchronous Event Handling Latency
-----------------------------------

jvmsim disabled
Running 1000000 iterations
Segmentation fault

---

Any ideas?

-Greg

>   I installed the LTP rpm and I dont seem to have tests by that
> name.  I have a 26.5-rt9 kernel all configured and ready to go but no
> way to reproduce this issue.  Please advise.
>
> Regards,
> -Greg
>
>
>   
>> login: cpu 0x2: Vector: 700 (Program Check) at [c0000000e8e875d0]
>>     pc: c00000000005110c: .pick_next_pushable_task+0x54/0x9c
>>     lr: c000000000059f50: .push_rt_task+0x44/0x2b4
>>     sp: c0000000e8e87850
>>    msr: 8000000000021032
>>   current = 0xc0000000ea5bb2e0
>>   paca    = 0xc000000000608700
>>     pid   = 2811, comm = async_handler
>> kernel BUG at kernel/sched_rt.c:1041! <---------------------
>> enter ? for help
>> [link register   ] c000000000059f50 .push_rt_task+0x44/0x2b4
>> [c0000000e8e87850] c0000000e8e878f0 (unreliable)
>> [c0000000e8e87900] c00000000005a1dc .push_rt_tasks+0x1c/0x38
>> [c0000000e8e87980] c00000000005a21c .post_schedule_rt+0x24/0x44
>> [c0000000e8e87a10] c000000000057cbc .finish_task_switch+0xd0/0x180
>> [c0000000e8e87ab0] c0000000003b6e88 .__schedule+0x6e0/0x798
>> [c0000000e8e87b90] c0000000003b7148 .schedule+0xec/0x11c
>> [c0000000e8e87c10] c0000000003b7a40 .do_nanosleep+0x6c/0xcc
>> [c0000000e8e87c90] c000000000080738 .hrtimer_nanosleep+0x7c/0x100
>> [c0000000e8e87d90] c000000000080830 .sys_nanosleep+0x74/0x94
>> [c0000000e8e87e30] c0000000000086ac syscall_exit+0x0/0x40
>> --- Exception: c00 (System Call) at 0000008026449844
>> SP (400014185f0) is in userspace
>>
>>
>> This is generated by the BUG_ON lines in the pick_next_pushable function
>> introduced by the sched-only-push-once-per-queue.patch .
>>
>> The -rt kernel prior to this patch didnot give such BUGes.
>>
>> All this was tried with
>> CONFIG_GROUP_SCHED=N
>> CONFIG_RT_GROUP_SCHED=N
>>
>>
>> Setting the options
>> CONFIG_GROUP_SCHED=y
>> CONFIG_RT_GROUP_SCHED=Y,
>> seems to solve the problem.
>>
>>
>>
>>   
>>     
>
>
>

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