makedumpfile: a feature question about filtering

[piliu]

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.

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.

This somewhat overlaps with the function of crash utility. And I want to
know if this feature is acceptable in upstream.

Any comment and suggestion?

Thanks,
Pingfan