Re: [PATCH v2] Revert "mm/page_alloc: fix memmap_init_zone pageblock alignment"

[Michal Hocko]

On Thu 15-03-18 11:28:27, Linus Torvalds wrote:
> On Thu, Mar 15, 2018 at 11:21 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> >
> > Well, pfn_valid says that a given pfn is backed by a real memory and it
> > has a valid struct page backing it.
> 
> No, it really just says the latter. There should be a "struct page" for it.

You are right! A simple example could be non volatile memory. That is
certainly not RAM but it has pfn_valid memory. Sorry about the
confusion.
-- 
Michal Hocko
SUSE Labs