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    SubjectRe: can device drivers return non-ram via vm_ops->nopage?

    On Sat, 20 Mar 2004, Andrea Arcangeli wrote:
    > The only bugreport I've got so far for the latest anon_vma code is from
    > Jens, and it's a device driver bug in my opinion, but I'd like to have a
    > definitive confirmation from you about the ->nopage API.

    I'd say that this is definitely a driver bug.

    If a driver wants to map non-RAM pages, that's perfectly ok, but it MUST
    NOT happen through "nopage()". The driver should map them with
    "remap_page_range()", and thus never take a page fault for such pages at

    There is no reason to ever lazily map non-RAM pages - clearly they aren't
    using any "real memory", so there is no reason to not fill the page tables
    at mmap() time.

    In other words, the driver is horribly broken.

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