On Mon, Jun 01, 2015 at 03:58:18PM +0200, Peter Zijlstra wrote: > Hi, > > Mike stumbled over a cute bug where the RT/DL balancing ops caused a bug. > > 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.
s/\./ 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 for well over an hour on my ivb-ep. I've not yet > tested it on anything bigger. > -- 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/
