Revert "sched: Fix sched_fork() access an invalid sched_task_group"

hulk inclusion
category: bugfix
bugzilla: 186973, https://gitee.com/openeuler/kernel/issues/I5CA6K
CVE: NA

--------------------------------

This reverts commit 74bd9b82.
Signed-off-by: NZhang Qiao <zhangqiao22@huawei.com>
Reviewed-by: NChen Hui <judy.chenhui@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

include/linux/sched/task.h

@@ -33,7 +33,6 @@ extern asmlinkage void schedule_tail(struct task_struct *prev);
 extern void init_idle(struct task_struct *idle, int cpu);
 
 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
-extern void sched_post_fork(struct task_struct *p);
 extern void sched_dead(struct task_struct *p);
 
 void __noreturn do_task_dead(void);

kernel/fork.c

@@ -2171,7 +2171,6 @@ static __latent_entropy struct task_struct *copy_process(
 
 	proc_fork_connector(p);
 	cgroup_post_fork(p);
-	sched_post_fork(p);
 	cgroup_threadgroup_change_end(current);
 	perf_event_fork(p);
 

kernel/sched/core.c

@@ -2298,6 +2298,8 @@ static inline void init_schedstats(void) {}
  */
 int sched_fork(unsigned long clone_flags, struct task_struct *p)
 {
+	unsigned long flags;
+
 	__sched_fork(clone_flags, p);
 	/*
 	 * We mark the process as NEW here. This guarantees that
@@ -2341,26 +2343,6 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 
 	init_entity_runnable_average(&p->se);
 
-#ifdef CONFIG_SCHED_INFO
-	if (likely(sched_info_on()))
-		memset(&p->sched_info, 0, sizeof(p->sched_info));
-#endif
-#if defined(CONFIG_SMP)
-	p->on_cpu = 0;
-#endif
-	init_task_preempt_count(p);
-#ifdef CONFIG_SMP
-	plist_node_init(&p->pushable_tasks, MAX_PRIO);
-	RB_CLEAR_NODE(&p->pushable_dl_tasks);
-#endif
-
-	return 0;
-}
-
-void sched_post_fork(struct task_struct *p)
-{
-	unsigned long flags;
-
 	/*
 	 * The child is not yet in the pid-hash so no cgroup attach races,
 	 * and the cgroup is pinned to this child due to cgroup_fork()
@@ -2378,6 +2360,20 @@ void sched_post_fork(struct task_struct *p)
 	if (p->sched_class->task_fork)
 		p->sched_class->task_fork(p);
 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+#ifdef CONFIG_SCHED_INFO
+	if (likely(sched_info_on()))
+		memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif
+#if defined(CONFIG_SMP)
+	p->on_cpu = 0;
+#endif
+	init_task_preempt_count(p);
+#ifdef CONFIG_SMP
+	plist_node_init(&p->pushable_tasks, MAX_PRIO);
+	RB_CLEAR_NODE(&p->pushable_dl_tasks);
+#endif
+	return 0;
 }
 
 unsigned long to_ratio(u64 period, u64 runtime)