psi: fix wrong iteration in iterate_groups

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I562O9
CVE: NA
backport: openEuler-22.03-LTS

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

It is different to get the cgroup that is used to update psi info in
cgroup v1 and cgroup v2.

task_cgroup can only used in cgroup v1, so add branch to achieve this.
Signed-off-by: NChen Wandun <chenwandun@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/sched/psi.c

@@ -757,9 +757,13 @@ static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
 			cgroup = task->cgroups->dfl_cgrp;
 		else {
 #ifdef CONFIG_CGROUP_CPUACCT
+			if (!cgroup_subsys_on_dfl(cpuacct_cgrp_subsys)) {
 				rcu_read_lock();
 				cgroup = task_cgroup(task, cpuacct_cgrp_id);
 				rcu_read_unlock();
+			} else {
+				cgroup = task->cgroups->dfl_cgrp;
+			}
 #else
 			cgroup = NULL;
 #endif