On Mon, Dec 10, 2018 at 05:30:09PM +0100, Peter Zijlstra wrote: > On Mon, Dec 10, 2018 at 05:20:10PM +0100, Michal Hocko wrote: > > > OK, no real objections to the thing. Just so long we're all on the same > > > page as to what it does and doesn't do ;-) > > > > I am not really sure whether there are other potential users besides > > this one and whether the check as such is justified. > > It's a debug option... > > > > I suppose you could extend the check to include schedule_debug() as > > > well, maybe something like: > > > > Do you mean to make the check cheaper? > > Nah, so the patch only touched might_sleep(), the below touches > schedule(). > > If there were a patch that hits schedule() without going through a > might_sleep() (rare in practise I think, but entirely possible) then you > won't get a splat without something like the below on top. We have a bunch of schedule() calls in i915, for e.g. waiting for multiple events at the same time (when we want to unblock if any of them fire). And there's no might_sleep in these cases afaict. Adding the check in schedule() sounds useful, I'll include your snippet in v2. Plus try a bit better to explain in the commit message why Michal suggested these. Thanks, Daniel > > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > > index f66920173370..b1aaa278f1af 100644 > > > --- a/kernel/sched/core.c > > > +++ b/kernel/sched/core.c > > > @@ -3278,13 +3278,18 @@ static noinline void __schedule_bug(struct task_struct *prev) > > > /* > > > * Various schedule()-time debugging checks and statistics: > > > */ > > > -static inline void schedule_debug(struct task_struct *prev) > > > +static inline void schedule_debug(struct task_struct *prev, bool preempt) > > > { > > > #ifdef CONFIG_SCHED_STACK_END_CHECK > > > if (task_stack_end_corrupted(prev)) > > > panic("corrupted stack end detected inside scheduler\n"); > > > #endif > > > > > > +#ifdef CONFIG_DEBUG_ATOMIC_SLEEP > > > + if (!preempt && prev->state && prev->non_block_count) > > > + // splat > > > +#endif > > > + > > > if (unlikely(in_atomic_preempt_off())) { > > > __schedule_bug(prev); > > > preempt_count_set(PREEMPT_DISABLED); > > > @@ -3391,7 +3396,7 @@ static void __sched notrace __schedule(bool preempt) > > > rq = cpu_rq(cpu); > > > prev = rq->curr; > > > > > > - schedule_debug(prev); > > > + schedule_debug(prev, preempt); > > > > > > if (sched_feat(HRTICK)) > > > hrtick_clear(rq); > > > > -- > > Michal Hocko > > SUSE Labs -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx