1 files changed, 17 insertions, 1 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 5a2089492a98..1d4acbea9e60 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -2348,6 +2348,15 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
         if (unlikely(se == pse))
                 return;
 
+        /*
+         * This is possible from callers such as pull_task(), in which we
+         * unconditionally check_prempt_curr() after an enqueue (which may have
+         * lead to a throttle).  This both saves work and prevents false
+         * next-buddy nomination below.
+         */
+        if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
+                return;
+
         if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
                 set_next_buddy(pse);
                 next_buddy_marked = 1;
@@ -2356,6 +2365,12 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
         /*
          * We can come here with TIF_NEED_RESCHED already set from new task
          * wake up path.
+         *
+         * Note: this also catches the edge-case of curr being in a throttled
+         * group (e.g. via set_curr_task), since update_curr() (in the
+         * enqueue of curr) will have resulted in resched being set.  This
+         * prevents us from potentially nominating it as a false LAST_BUDDY
+         * below.
          */
         if (test_tsk_need_resched(curr))
                 return;
@@ -2474,7 +2489,8 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp
 {
         struct sched_entity *se = &p->se;
 
-        if (!se->on_rq)
+        /* throttled hierarchies are not runnable */
+        if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
                 return false;
 
         /* Tell the scheduler that we'd really like pse to run next. */