RCU stall on panda

Alex Shi alex.shi at linaro.org
Thu May 15 01:44:29 PDT 2014

On 05/13/2014 11:32 PM, Tony Lindgren wrote:
> * Alex Shi <alex.shi at linaro.org> [140512 23:37]:
>> On 05/13/2014 05:21 AM, Tony Lindgren wrote:
>>> * Paul E. McKenney <paulmck at linux.vnet.ibm.com> [140505 11:11]:
>>>> On Mon, May 05, 2014 at 05:39:43PM +0800, Alex Shi wrote:
>>>>> I keep seeing the RCU stall problem on panda board from 3.10 kernel to latest upstream kernel
>>>>> and google find some one report it before: https://lkml.org/lkml/2012/9/20/519
>>>>> Is it the hardware issue or a real software problem?
>>>> I cannot distinguish between hardware and software from the trace below,
>>>> but given that you are also seeing a soft lockup, either way you do
>>>> appear to have a real problem as opposed to an RCU CPU stall warning
>>>> false positive.
>>> Looks like you have CPU_IDLE enabled on panda. Hangs with current linux
>>> next with CPU_IDLE are currently being discussed on the linux-omap list
>>> in thread "omap4-panda-es boot issues with v3.15-rc4"
>>> I've seen occasional system hangs, and I've also noticed that doing
>>> ctrl-a-f h or ctrl-a-f l for sysrq backtrace can unlock the system
>>> producing similar errors to the below.
>> Thanks a lot for the info.
>> In fact, the oops keeps in upstream kernel from 3.10 to latest.
> Care to test if the revert of commit cb7094 Santosh posted as
> "[PATCH] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled"
> solves the problem for you?

After enable this patch, system maybe hang in idle. :(

> Regards,
> Tony


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