5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> commit f2aa197e4794bf4c2c0c9570684f86e6fa103e8b upstream. task_css_set_check() will use rcu_dereference_check() to check for rcu_read_lock_held() on the read-side, which is not true after commit dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This commit drop explicit rcu_read_lock(), change to RCU-sched read-side critical section. So fix the RCU warning by adding check for rcu_read_lock_sched_held(). Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock") Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> Reported-by: syzbot+16e3f2c77e7c5a0113f9@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Tested-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220305034103.57123-1-zhouchengming@xxxxxxxxxxxxx Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- include/linux/cgroup.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 7653f54189502..c9c430712d471 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -451,6 +451,7 @@ extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ + rcu_read_lock_sched_held() || \ lockdep_is_held(&cgroup_mutex) || \ lockdep_is_held(&css_set_lock) || \ ((task)->flags & PF_EXITING) || (__c)) -- 2.40.1