# Re: \[PATCH v1 05/11\] mm/sparse-vmemmap: add a pgmap argument to section activation

- From: Dan Williams \<hidden\>
- Date: 2021-05-05 22:34:57 
- List: linux-mm
- Page: https://ratatoskr.run/linux-mm/2021/05/6507974
- Thread: https://ratatoskr.run/linux-mm/2021/03/6507171/t.md

```text
On Thu, Mar 25, 2021 at 4:10 PM Joao Martins [ref] wrote:
>
> @altmap is stored in a dev_pagemap, but it will be repurposed for
> hotplug memory for storing the memmap in the hotplugged memory[*] and
> reusing the altmap infrastructure to that end. This is to say that
> altmap can't be replaced with a @pgmap as it is going to cover more than
> dev_pagemap backend altmaps.

I was going to say, just pass the pgmap and lookup the altmap from
pgmap, but Oscar added a use case for altmap independent of pgmap. So
you might refresh this commit message to clarify why passing pgmap by
itself is not sufficient.

Other than that, looks good.

```