Re: [PATCH] sched: fix to use invalid sched_class

[Dmitry Adamushko <dmitry.adamushko@gmail.com>]

> > Hi Ingo,
> > 
> > I found an issue about the scheduler.
> > If you need a test case, please let me know.
> > Here is a patch.
> > [ ... ]
> > The new thread should be valid scheduler class before queuing.
> > This patch fixes to set the suitable scheduler class.
> 
> Nice fix! It's a 2.6.23 must-have fix - i'll push it out into the 
> scheduler tree. Thanks!

I think, the following approach would be a bit more appropriate
(the missing addition to the already existing "don't leak PI boosting prio"):

(not tested)

---
diff --git a/kernel/sched.c b/kernel/sched.c
index bc1a625..da2139e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1646,6 +1646,8 @@ void sched_fork(struct task_struct *p, int clone_flags)
 	 * Make sure we do not leak PI boosting priority to the child:
 	 */
 	p->prio = current->normal_prio;
+	if (!rt_prio(p->prio))
+		p->sched_class = &fair_sched_class;
 
 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
 	if (likely(sched_info_on()))

---