On Thu, Jun 11, 2015 at 02:46:36PM +0200, Peter Zijlstra wrote: > Mike stumbled over a cute bug where the RT/DL balancing ops caused a bug.
Hello. We also faced this bug in our embedded product using stable tree. Eventually, we found that these patch set exactly dealt with the problem. Now, I am just curious about if you have any plans to merge this to stable trees to make the stable trees stabler. Hm? > > The exact scenario is __sched_setscheduler() changing a (runnable) task from > FIFO to OTHER. In swiched_from_rt(), where we do pull_rt_task() we temporarity > drop rq->lock. This gap allows regular cfs load-balancing to step in and > migrate our task. > > However, check_class_changed() will happily continue with switched_to_fair() > which assumes our task is still on the old rq and makes the kernel go boom. > > Instead of trying to patch this up and make things complicated; simply > disallow > these methods to drop rq->lock and extend the current post_schedule stuff into > a balancing callback list, and use that. > > This survives Mike's testcase. > > Changes since -v3: > - reworked the hrtimer stuff, again. -- Kirill, Oleg > - small changes to the new lockdep stuff > > Changes since -v2: > - reworked the hrtimer patch. -- Kirill, tglx > - added lock pinning > > Changes since -v1: > - make SMP=n build, > - cured switched_from_dl()'s cancel_dl_timer(). > > no real tests on the new parts other than booting / building kernels. > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
