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    SubjectRe: [RFC][patch 0/2] mm: remove PageReserved
    --Russell King <> wrote (on Tuesday, August 09, 2005 08:08:53 +0100):

    > On Tue, Aug 09, 2005 at 02:59:53PM +1000, Nick Piggin wrote:
    >> 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.
    > The usage of "valid ram" here is confusing - that's not what PageReserved
    > is all about. It's about valid RAM which is managed by method other
    > than the usual page counting. Non-reserved RAM is also valid RAM, but
    > is managed by the kernel in the usual way.
    > The former is available for remap_pfn_range and ioremap, the latter is
    > not.
    > On the other hand, the validity of an apparant RAM address can only be
    > tested using its pfn with pfn_valid().
    > Can we straighten out the terminology so it's less confusing please?

    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.


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      Last update: 2005-08-09 16:41    [W:4.206 / U:0.148 seconds]
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