Re: [PATCH v3 5/9] powerpc: Use preempt_model_str().

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 09/02/2025 à 15:38, Shrikanth Hegde a écrit :
> 
> 
> On 2/8/25 23:25, Christophe Leroy wrote:
>>
>>
>> Le 08/02/2025 à 14:42, Shrikanth Hegde a écrit :
>>>
>>>
>>> On 2/8/25 18:25, Christophe Leroy wrote:
>>>>
>>>>
>>>> Le 08/02/2025 à 08:35, Shrikanth Hegde a écrit :
>>>>>
>>>>>
>>>>> On 2/4/25 13:52, Sebastian Andrzej Siewior wrote:
>>>>>> Use preempt_model_str() instead of manually conducting the preemption
>>>>>> model. Use pr_emerg() instead of printk() to pass a loglevel.
>>>>>
>>>>> even on powerpc, i see __die ends up calling show_regs_print_info().
>>>>> Why print it twice?
>>>>
>>>> I don't understand what you mean, what is printed twice ?
>>>>
>>>> I can't see show_regs_print_info() printing the preemption model, am 
>>>> I missing something ?
>>>>
>>>
>>> Patch 2/9 add preemption string in dump_stack_print_info.
>>>
>>> __die -> show_regs() _> show_regs_print_info() -> 
>>> dump_stack_print_info() -> init_utsname()->version, 
>>> preempt_model_str(), BUILD_ID_VAL);
>>>
>>> Wont we end up in this path?
>>
>> Indeed I missed that. You are right, we now get the information twice:
> 
> I think we can remove it from arch specific code and rely on lib/ 
> dump_stack?

Yes I guess so.

> 
> And similar concern of printk vs pr_warn/pr_emerg would apply to that as 
> well i guess.

Well, powerpc's show_regs() calls it with 
show_regs_print_info(KERN_DEFAULT);

And dump_stack_print_info() uses printk with log_lvl so there should be 
no concern here.

> 
>>
>> [  440.068216] BUG: Unable to handle kernel data access on write at 
>> 0xc09036fc