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SubjectRe: Bug in scheduler when using rt_mutex
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On Wed, 2011-01-19 at 14:58 +0200, Onkalo Samu wrote:
> On Wed, 2011-01-19 at 12:30 +0100, ext Peter Zijlstra wrote:
> > On Wed, 2011-01-19 at 11:38 +0100, Peter Zijlstra wrote:
> >
> > > Hrm, I think the to bit is not needed with the from thing in place, the
> > > enqueue from _setprio will already have added min_vruntime
> >
> >
> > Would lead to something like this:
> >
>
> Doesn't work in my case.

When the task is sleeping rt_mutex_setprio
doesn't call check_class_changed since the task is not
in queue at that moment I think.

>
> > ---
> > Index: linux-2.6/kernel/sched.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/sched.c
> > +++ linux-2.6/kernel/sched.c
> > @@ -8108,6 +8108,8 @@ EXPORT_SYMBOL(__might_sleep);
> > #ifdef CONFIG_MAGIC_SYSRQ
> > static void normalize_task(struct rq *rq, struct task_struct *p)
> > {
> > + struct sched_class *prev_class = p->sched_class;
> > + int old_prio = p->prio;
> > int on_rq;
> >
> > on_rq = p->se.on_rq;
> > @@ -8118,6 +8120,8 @@ static void normalize_task(struct rq *rq
> > activate_task(rq, p, 0);
> > resched_task(rq->curr);
> > }
> > +
> > + check_class_changed(rq, p, prev_class, old_prio, task_current(rq, p));
> > }
> >
> > void normalize_rt_tasks(void)
> > Index: linux-2.6/kernel/sched_fair.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/sched_fair.c
> > +++ linux-2.6/kernel/sched_fair.c
> > @@ -4066,11 +4066,30 @@ static void prio_changed_fair(struct rq
> > check_preempt_curr(rq, p, 0);
> > }
> >
> > +static void
> > +switched_from_fair(struct rq *rq, struct task_struct *p, int running)
> > +{
> > + struct sched_entity *se = &p->se;
> > + struct cfs_rq *cfs_rq = cfs_rq_of(se);
> > +
> > + /*
> > + * Ensure the task's vruntime is normalized, so that when its
> > + * switched back to the fair class the enqueue_entity(.flags=0) will
> > + * do the right thing.
> > + *
> > + * If it was on_rq, then the dequeue_entity(.flags=0) will already
> > + * have normalized the vruntime, if it was !on_rq, then only when
> > + * the task is sleeping will it still have non-normalized vruntime.
> > + */
> > + if (!se->on_rq && p->state != TASK_RUNNING)
> > + se->vruntime -= cfs_rq->min_vruntime;
> > +}
> > +
> > /*
> > * We switched to the sched_fair class.
> > */
> > -static void switched_to_fair(struct rq *rq, struct task_struct *p,
> > - int running)
> > +static void
> > +switched_to_fair(struct rq *rq, struct task_struct *p, int running)
> > {
> > /*
> > * We were most likely switched from sched_rt, so
> > @@ -4163,6 +4182,7 @@ static const struct sched_class fair_sch
> > .task_fork = task_fork_fair,
> >
> > .prio_changed = prio_changed_fair,
> > + .switched_from = switched_from_fair,
> > .switched_to = switched_to_fair,
> >
> > .get_rr_interval = get_rr_interval_fair,
> >
>
>




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