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    SubjectRe: copy_to_user to a kmapped address
    On Mon, Aug 26, 2002 at 04:19:37PM -0500, Jeff Dike wrote:
    > Is this (in file_read_actor) bogus or am I missing something?
    > 1621 kaddr = kmap(page);
    > 1622 left = __copy_to_user(desc->buf, kaddr + offset, size);
    > 1623 kunmap(page);
    > It seems to me that copy_to_user should be able to assume that the destination
    > address is a user address.
    > This is biting me because I'm moving the UML kernel into a separate address
    > space, so there's no way, in general, to tell the difference between a kernel
    > address and a userspace address.

    Umm, that's copying from kaddr + offset _to_ desc->buf. desc->buf
    should be the user space address, and kaddr + offset a kernel address:

    unsigned long __copy_to_user(void *to, const void *from, unsigned long n)

    Russell King ( The developer of ARM Linux

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