Re: frequent lockups in 3.18rc4

[Lai Jiangshan]

On 12/02/2014 03:14 AM, Paul E. McKenney wrote:
> On Sun, Nov 30, 2014 at 11:02:43PM -0200, DÃniel Fraga wrote:
>> On Sun, 30 Nov 2014 16:21:19 -0800
>> Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>
>>> Maybe you'll have to turn off RCU_CPU_STALL_VERBOSE first.
>>>
>>> Although I think you should be able to just edit the .config file,
>>> delete the like that says
>>>
>>>     CONFIG_TREE_PREEMPT_RCU=y
>>>
>>> and then just do a "make oldconfig", and then verify that
>>> TREE_PREEMPT_RCU hasn't been re-enabled by some dependency. But it
>>> shouldn't have, and that "make oldconfig" should get rid of anything
>>> that depends on TREE_PREEMPT_RCU.
>> 	
>> 	Ok, I did exactly that, but CONFIG_TREE_PREEMPT_RCU is
>> re-enabled. I talked with Pranith Kumar and he suggested I could just
>> disable preemption (No Forced Preemption (Server)) and that's the only
>> way to disable CONFIG_TREE_PREEMPT_RCU.
> 
> If it would help to have !CONFIG_TREE_PREEMPT_RCU with CONFIG_PREEMPT=y,

It is needed at lest for testing.

CONFIG_TREE_PREEMPT_RCU=y with CONFIG_PREEMPT=n is needed for testing too.

Please enable them (or enable them under CONFIG_RCU_TRACE=y)

> please let me know and I will create a patch that forces this.
> (Not mainline material, but if it helps with debug...)
> 
> 							Thanx, Paul
> 
>> 	Now I'll try to make the system freeze, then I'll send
>> you the Call trace.
>>
>> 	Thanks.
>>
>> -- 
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