FROM: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=c85c6fadbef0a3eab41540ea628fa8fe8928c820
Try: Fix sched_fork() access an invalid sched_task_group

--- patch-5.10-ck1	2021-11-21 15:28:49.188267764 +0800
+++ patch-5.10.80-ck1	2021-11-21 15:57:02.448246461 +0800
@@ -3455,7 +3455,7 @@
 index 000000000000..9478e2d473b7
 --- /dev/null
 +++ b/kernel/sched/MuQSS.c
-@@ -0,0 +1,7866 @@
+@@ -0,0 +1,7868 @@
 +// SPDX-License-Identifier: GPL-2.0
 +/*
 + *  kernel/sched/MuQSS.c, was kernel/sched.c
@@ -5714,8 +5714,6 @@
 + */
 +int sched_fork(unsigned long __maybe_unused clone_flags, struct task_struct *p)
 +{
-+	unsigned long flags;
-+
 +#ifdef CONFIG_PREEMPT_NOTIFIERS
 +	INIT_HLIST_HEAD(&p->preempt_notifiers);
 +#endif
@@ -5772,14 +5770,6 @@
 +		p->sched_reset_on_fork = 0;
 +	}
 +
-+	/*
-+	 * Silence PROVE_RCU.
-+	 */
-+	raw_spin_lock_irqsave(&p->pi_lock, flags);
-+	rseq_migrate(p);
-+	set_task_cpu(p, smp_processor_id());
-+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
-+
 +#ifdef CONFIG_SCHED_INFO
 +	if (unlikely(sched_info_on()))
 +		memset(&p->sched_info, 0, sizeof(p->sched_info));
@@ -5789,8 +5779,20 @@
 +	return 0;
 +}
 +
-+void sched_post_fork(struct task_struct *p)
++void sched_post_fork(struct task_struct *p, struct kernel_clone_args *kargs)
 +{
++	unsigned long flags;
++	/*
++	 * Silence PROVE_RCU.
++	 */
++	raw_spin_lock_irqsave(&p->pi_lock, flags);
++	rseq_migrate(p);
++	/*
++	 * We're setting the CPU for the first time, we don't migrate,
++	 * so use set_task_cpu().
++	 */
++	set_task_cpu(p, smp_processor_id());
++	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
 +}
 +
 +#ifdef CONFIG_SCHEDSTATS