From: Xunlei Pang <xlpang@linux.alibaba.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4OF4N ------------------------------------------ task_css() should be protected by rcu. In my environment if not protected by rcu qemu may fail to start. Fixes: a885e3f9e457 ("psi: support psi under cgroup v1") Reported-by: Yang Yingliang <yangyingliang@huawei.com> Acked-by: Michael Wang <yun.wany@linux.alibaba.com> Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com> Signed-off-by: Yihao Wu <wuyihao@linux.alibaba.com> Acked-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Chen Wandun <chenwandun@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- kernel/sched/psi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index ddbd3d79b988..360f13382069 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -755,12 +755,15 @@ static struct psi_group *iterate_groups(struct task_struct *task, void **iter) if (!*iter) { if (static_branch_likely(&psi_v1_disabled)) cgroup = task->cgroups->dfl_cgrp; - else + else { #ifdef CONFIG_CGROUP_CPUACCT + rcu_read_lock(); cgroup = task_cgroup(task, cpuacct_cgrp_id); + rcu_read_unlock(); #else cgroup = NULL; #endif + } } else if (*iter == &psi_system) return NULL; else -- 2.20.1