On Wed, Jul 13, 2022 at 09:50:14AM +0200, Juri Lelli wrote: > Tasks the are being deboosted from SCHED_DEADLINE might enter > enqueue_task_dl() one last time and hit an erroneous BUG_ON condition: > since they are not boosted anymore, the if (is_dl_boosted()) branch is > not taken, but the else if (!dl_prio) is and inside this one we > BUG_ON(!is_dl_boosted), which is of course false (BUG_ON triggered) > otherwise we had entered the if branch above. Long story short, the > current condition doesn't make sense and always leads to triggering of a > BUG. > > Fix this by only checking enqueue flags, properly: ENQUEUE_REPLENISH has > to be present, but additional flags are not a problem. > > Fixes: 2279f540ea7d ("sched/deadline: Fix priority inheritance with multiple scheduling classes") > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> > --- > kernel/sched/deadline.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 5867e186c39a..0447d46f4718 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -1703,7 +1703,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) > * the throttle. > */ > p->dl.dl_throttled = 0; > - BUG_ON(!is_dl_boosted(&p->dl) || flags != ENQUEUE_REPLENISH); > + BUG_ON(!(flags & ENQUEUE_REPLENISH)); While there, can we perhaps make it less fatal?