Re: [PATCH RFC 05/13] mm/rmap: remove do_page_add_anon_rmap()

[Linus Torvalds]

On Thu, Feb 24, 2022 at 4:29 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> ... and instead convert page_add_anon_rmap() to accept flags.

Can you fix the comment above the RMAP_xyz definitions? That one still says

  /* bitflags for do_page_add_anon_rmap() */

that tnow no longer exists.

Also, while this kind of code isn't unusual, I think it's still confusing:

> +               page_add_anon_rmap(page, vma, addr, 0);

because when reading that, at least I go "what does 0 mean? Is it a
page offset, or what?"

It might be a good idea to simply add a

  #define RMAP_PAGE 0x00

or something like that, just to have the callers all make it obvious
that we're talking about that RMAP_xyz bits - even if some of them may
be default.

(Then using an enum of a special type is something we do if we want to
add extra clarity or sparse testing, I don't think there are enough
users for that to make sense)

               Linus