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    SubjectRe: [PATCH/RFC] Shared page tables

    Here's another one to keep you awake at night:

    mmap a shared, anonymous region of 8MB (2MB aligned), and fork off some
    children (4 is good enough for me). In each child, munmap() a 2 MB portion
    of the shared region (starting at offset 2MB in the shared region) and then
    mmap() a private, anonymous region in its place. Have each child store some
    unique data in that region, sleep for a bit and then go look to see if its
    data is still there.

    Under 2.6.15, this works just fine. Under 2.6.15 + shpt patch, each child
    still points at the shared region and steps on the data of the other

    I imagine the above gets even more interesting if the offset or length of the
    unmapped region is not a multiple of the 2MB alignment.

    All of these test cases are for Opteron. Your alignment may vary.

    (Sorry about this... )

    Ray Bryant
    AMD Performance Labs Austin, Tx
    512-602-0038 (o) 512-507-7807 (c)

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      Last update: 2006-01-26 01:19    [W:0.021 / U:4.944 seconds]
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