Re: [RFC][patch 0/2] mm: remove PageReserved

Nigel Cunningham
2005-08-09T05:11:34Z

Hi Nick et al.

On Tue, 2005-08-09 at 14:59, Nick Piggin wrote:
> Nigel Cunningham wrote:
> > Hi.
> >
> > On Tue, 2005-08-09 at 07:09, Daniel Phillips wrote:
> >
> >>>It doesn't look like they'll be able to easily free up a page
> >>>flag for 2 reasons. First, PageReserved will probably be kept
> >>>around for at least one release. Second, swsusp and some arch
> >>>code (ioremap) wants to know about struct pages that don't point
> >>>to valid RAM - currently they use PageReserved, but we'll probably
> >>>just introduce a PageValidRAM or something when PageReserved goes.
> >
> >
> > Changing the e820 code so it sets PageNosave instead of PageReserved,
> > along with a couple of modifications in swsusp itself should get rid of
> > the swsusp dependency.
> >
>
> That would work for swsusp, but there are other users that want to
> know if a struct page is valid ram (eg. ioremap), so in that case
> swsusp would not be able to mess with the flag.

Um. Mess with which flag? I guess you mean Reserved. I was saying that
imaging Reserved going away, so for the short term I'd be meaning making
the e820 set both Nosave and Reserved for those pages (which is what the
Suspend2 patches do so as to play nicely with swsusp - I don't use
Reserved at all).

> I do think swsusp should (and can, quite easily though I may have
> missed something) consolidate PG_nosave and PG_nosave_free, however
> that's out of the scope of this patch.

I won't comment here. I don't start at swsusp code that much :>

Nigel
--
Evolution.
Enumerate the requirements.
Consider the interdependencies.
Calculate the probabilities.