On Thu, Jan 16, 2020 at 3:50 PM Michal Hocko <mhocko@xxxxxxxx> wrote:
>
> On Thu 16-01-20 11:01:08, Pingfan Liu wrote:
> > When fully deactivated, it is meaningless to keep the value of a section's
> > mem_map. And its mem_map will be reassigned during re-added.
> >
> > Beside this, it breaks the user space tool "makedumpfile", which makes
> > assumption that a hot-removed section having mem_map as NULL.
>
> We used to do that before ba72b4c8cf60 ("mm/sparsemem: support
> sub-section hotplug"). Dan was this an intentional change?
I do not know the purpose of this. But the change just leave section
start pfn in fully deactivated section_mem_map, and not used any more.
Thanks,
Pingfan
