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    Subject[54/55] perf: overflow/perf_count_sw_cpu_clock crashes recent kernels
    2.6.32-longterm review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Peter Zijlstra <a.p.zijlstra@chello.nl>

    The below patch is for -stable only, upstream has a much larger patch
    that contains the below hunk in commit a8b0ca17b80e92faab46ee7179ba9e99ccb61233

    Vince found that under certain circumstances software event overflows
    go wrong and deadlock. Avoid trying to delete a timer from the timer
    callback.

    Reported-by: Vince Weaver <vweaver1@eecs.utk.edu>
    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    kernel/perf_event.c | 8 ++------
    1 file changed, 2 insertions(+), 6 deletions(-)

    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -3694,12 +3694,8 @@ static int __perf_event_overflow(struct
    if (events && atomic_dec_and_test(&event->event_limit)) {
    ret = 1;
    event->pending_kill = POLL_HUP;
    - if (nmi) {
    - event->pending_disable = 1;
    - perf_pending_queue(&event->pending,
    - perf_pending_event);
    - } else
    - perf_event_disable(event);
    + event->pending_disable = 1;
    + perf_pending_queue(&event->pending, perf_pending_event);
    }

    perf_event_output(event, nmi, data, regs);



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