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    SubjectRe: [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work
    Date
    Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:
    > ----- On May 5, 2020, at 9:16 AM, Thomas Gleixner tglx@linutronix.de wrote:
    >
    >> From: Peter Zijlstra <peterz@infradead.org>
    >>
    >
    > Patch title: singal -> signal.
    >
    >> Convert #MC over to using task_work_add(); it will run the same code
    >> slightly later, on the return to user path of the same exception.
    >
    > So I suspect that switching the order between tracehook_notify_resume()
    > (which ends up calling task_work_run()) and do_signal() done by an
    > earlier patch in this series intends to ensure the information about the
    > instruction pointer causing the #MC is not overwritten by do_signal()
    > (but I'm just guessing).

    No, it does not. See the ordering discussion.

    Aside of that signal never transported any address information. It uses
    force_sig(SIGBUS).

    Even if a different signal would be sent first then the register frame
    of the #MC is still there when the fatal signal is sent later.

    But even w/o changing the ordering the taskwork check in do_signal()
    runs the pending work before delivering anything.

    Thanks,

    tglx

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