K Prateek noticed we weren't setting the rq->next_class in
proxy_resched_idle(), when I was debugging an issue seen with
CONFIG_SCHED_PROXY_EXEC and some of Peter's new patches, and
suggested this fix.

So set rq->next_class when we temporarily switch the donor to
idle, so we don't accidentally call wakeup_preempt_fair()
with idle as the donor.

Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: John Stultz <jstultz@google.com>
---
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: kernel-team@android.com
---
 kernel/sched/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b8871449d3c69..0ec04008ccd6b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6645,6 +6645,7 @@ static inline void proxy_set_task_cpu(struct task_struct *p, int cpu)
 static inline struct task_struct *proxy_resched_idle(struct rq *rq)
 {
 	put_prev_set_next_task(rq, rq->donor, rq->idle);
+	rq->next_class = &idle_sched_class;
 	rq_set_donor(rq, rq->idle);
 	set_tsk_need_resched(rq->idle);
 	return rq->idle;
-- 
2.54.0.563.g4f69b47b94-goog

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     04f80f8b12a02fa2e0827c8f37eb357adca8ce44
Gitweb:        https://git.kernel.org/tip/04f80f8b12a02fa2e0827c8f37eb357adca8ce44
Author:        John Stultz <jstultz@google.com>
AuthorDate:    Thu, 14 May 2026 23:47:17 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 19 May 2026 12:17:39 +02:00

sched: Switch rq->next_class on proxy_resched_idle()

K Prateek noticed we weren't setting the rq->next_class in
proxy_resched_idle(), when I was debugging an issue seen with
CONFIG_SCHED_PROXY_EXEC and some of Peter's new patches, and
suggested this fix.

So set rq->next_class when we temporarily switch the donor to
idle, so we don't accidentally call wakeup_preempt_fair()
with idle as the donor.

Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260514234732.3170197-1-jstultz@google.com
---
 kernel/sched/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3ae5f19..77f4ebe 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6653,6 +6653,7 @@ static inline void proxy_set_task_cpu(struct task_struct *p, int cpu)
 static inline struct task_struct *proxy_resched_idle(struct rq *rq)
 {
 	put_prev_set_next_task(rq, rq->donor, rq->idle);
+	rq->next_class = &idle_sched_class;
 	rq_set_donor(rq, rq->idle);
 	set_tsk_need_resched(rq->idle);
 	return rq->idle;