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

From: Nick Piggin (nickpiggin_at_yahoo.com.au)
Date: 08/11/05

  • Next message: David Teigland: "Re: GFS - updated patches" 
    Date:	Thu, 11 Aug 2005 19:09:29 +1000
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>

    Benjamin Herrenschmidt wrote:
    > On Tue, 2005-08-09 at 20:41 +0100, Russell King wrote:
    >
    >>On Tue, Aug 09, 2005 at 07:38:52AM -0700, Martin J. Bligh wrote:
    >>
    >>>pfn_valid() doesn't tell you it's RAM or not - it tells you whether you
    >>>have a backing struct page for that address. Could be an IO mapped device,
    >>>a small memory hole, whatever.
    >>
    >>The only things which have a struct page is RAM. Nothing else does.
    >
    >
    > Well, not anymore :)
    >

    Well thanks everyone for the discussion and input. If I have missed
    answering a question, please just mail me privately to let me know.

    I guess that despite some architecture implementation differences,
    everyone will be happy to see PageReserved go from core code. So
    I will send Andrew the patches.

    After that, we have a few options to move forward with completely
    getting rid of the flag from the other funny places it has cropped
    up. A portable page_is_ram() sounds like the best way to go, as it
    would not use up a page flag.

    As far as ioremap goes - I would rather completely disallow it from
    remapping physical pages and enforce that where possible (eg. with
    page_is_ram()).

    However, these issues (page_is_ram, swsusp, ioremap) need not be
    tackled right now. I will bring them up on the lists some time after
    the core mm/ is working nicely without PageReserved.

    Thanks,
    Nick 

    -- 
SUSE Labs, Novell Inc.
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