On Tue, May 13, 2014 at 10:48:02PM +0200, Peter Zijlstra wrote: > On Tue, May 13, 2014 at 09:33:29PM +0200, Frederic Weisbecker wrote: > > On Tue, May 13, 2014 at 07:09:42PM +0200, Peter Zijlstra wrote: > > > On Tue, May 13, 2014 at 04:38:37PM +0200, Frederic Weisbecker wrote: > > > > We prepare for executing the full nohz kick through an irq work. But > > > > if we do this as is, we'll run into conflicting tick locking: the tick > > > > holds the hrtimer lock and the nohz kick may do so too. > > > > > > It does? How does the tick end up holding that lock? > > > > > > Normal hrtimer callbacks run without holding the hrtimer lock -- I made > > > it so. > > > > > > This means tick_sched_timer() is called without hrtimer lock, and I > > > don't see it taking it anywhere in tick_sched_do_timer() or > > > tick_sched_handle(). > > > > Check hrtimer_interrupt(), it takes the per cpu base->lock. > > check __run_hrtimer() which drops base->lock over calling ->function.
Oh! I had lockdep splats a few days ago. But I think I worked too many hours on it and eventually developed some brainfarted pet assumptions all along :-( It was probably due to some other mistakes of mine. Ok, lets try again. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
