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    SubjectRe: [patch] mspec - special memory driver and do_no_pfn handler

    On Thu, 16 Mar 2006, Andrew Morton wrote:
    > hm. Is that a superset of ->nopage? Should we be looking at
    > migrating over to ->nopfn, retire ->nopage?
    > <looks at the ghastly stuff in do_no_page>
    > Maybe not...

    Yeah, absolutely _not_.

    If we wouldn't pass the "struct page" around, we wouldn't have anything to
    synchronize with, and each nopage() function would have to do rmap stuff.

    That's actually how nopage() worked a long time ago (not rmap, but it was
    up the the low-level function to do all the page table logic etc).
    Switching to returning a structured return value and letting the generic
    VM code handle all the locking and the races was a _huge_ improvement.

    So yes, the modern "->nopage()" interface is less flexible, but it's less
    flexible for a very good reason.

    Quite frankly, I don't think nopfn() is a good interface. It's only usable
    for one single thing, so trying to claim that it's a generic VM op is
    really not valid. If (and that's a big if) we need this interface, we
    should just do it inside mm/memory.c instead of playing games as if it was

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      Last update: 2009-11-18 23:46    [W:0.021 / U:5.428 seconds]
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