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    SubjectRe: __update_max_tr: rcu_read_lock() used illegally while idle!
    On Tue, Jul 31, 2012 at 02:06:41PM -0400, Steven Rostedt wrote:
    > On Tue, 2012-07-31 at 10:44 -0700, Paul E. McKenney wrote:
    >
    > > OK, I interpret this as excluding NMI handlers, but please let me
    > > know if I am still being naive. ;-)
    > >
    >
    > You are correct. This is only called where lockdep is called (to trace
    > enabling of IRQS). Note, that its called before normal irqs are actually
    > enabled (interrupts are still disabled), this is why it's called outside
    > of the in_irq() sections, because it is called just before returning
    > back to process context.
    >
    > That said, because NMIs are so difficult, lockdep doesn't record the
    > disabling (and then enabling) of interrupts when an NMI triggers. Thus,
    > the irqsoff tracer also does not record NMIs. Which is fine, because
    > NMIs should not take long to run (we can add other mechanisms to time
    > NMI length if that is needed), and NMIs should not be enabling
    > interrupts nor taking any locks.
    >
    > >From arch/x86/kernel/entry_64.S:
    >
    > /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */

    Then the patch on my earlier email should do it for you.

    Thanx, Paul



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