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    SubjectRe: [patch] user-vm-unlock-2.5.31-A2

    On Thu, 15 Aug 2002, Linus Torvalds wrote:

    > The problem spot is the _fork_ from process X. Which gives a address in
    > process' _X_ virtual address space - used for SETTID.
    >
    > See? Process _X_ is not threaded, and is not maintaining any thread data
    > structures.

    okay, this is the misunderstanding then. If it fork()s and then uses some
    threading (which uses clone()) then in all cases i know about it must be
    linked against some threading library. Otherwise Y couldnt do a clone()
    call and expect threading to work. In theory Y could 'become' a
    threading-capable process, but right now no threading library i'm aware of
    allows this - lots of standard C calls must be threading-aware and
    threading-safe. So right now 'threading' is a property that comes with the
    process image at exec() time. But this must not be so from a conceptual
    angle, so i agree with you.

    (but the question is mostly academic anyway, because it makes perfect
    sense to use a pure SETTID for a completely unthreaded application, to get
    the fork() PID return value in the child's context as well.)

    Ingo

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