makedumpfile: a feature question about filtering

[piliu]

On 09/11/2020 04:53 PM, HAGIO KAZUHITO(萩尾　一仁) wrote:
> Hi Pingfan,
> 
> -----Original Message-----
>> Hello,
>>
>> There is an appeal which only wants to save some user page including env
>> and args pages, and discards the other user space pages.
> 
> I understand that it's helpful to get them even with -d 31 for crash's
> "ps -a" option..
> 
>>
>> To achieve this feature, mm_struct's members "arg_start, arg_end,
>> env_start, env_end;" should be accessed. So we need to export mm_struct
>> and init_mm through vmcore.
> 
> How many offsets/sizes will be required to walk all tasks?
At present, I think only the info "arg_start, arg_end, env_start,
env_end" in mm_struct are required.
> If kernel maintainers accept it, I will not oppose that feature..
OK, I will start with kernel side as the first step.
> 
> (or it would be simpler to mark the pages something special when allocating,
> but I don't feel like it's easy to change kernel to do so.)
Yes, I agree. From kernel side, the page is a normal user space page,
there should not be exception.

Thanks,
Pingfan