1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index de0bd26e520a..3c2a54f70ffe 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+        /*
+         * Strictly speaking this rcu_read_lock() is not needed since the
+         * task_group is tied to the cgroup, which in turn can never go away
+         * as long as there are tasks attached to it.
+         *
+         * However since task_group() uses task_subsys_state() which is an
+         * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
+         */
+        rcu_read_lock();
 #ifdef CONFIG_FAIR_GROUP_SCHED
         p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
         p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
         p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
         p->rt.parent = task_group(p)->rt_se[cpu];
 #endif
+        rcu_read_unlock();
 }
 
 #else