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()))
---
-