From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 6 Oct 2025 18:12:34 +0000 (+0200)
Subject: sched: Mandate shared flags for sched_change
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=73ec89a1ce4bce98f74b6520a95e64cd9986aae5;p=thirdparty%2Flinux.git

sched: Mandate shared flags for sched_change

Shrikanth noted that sched_change pattern relies on using shared
flags.

Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3d5659f136240..e2199e4db0dc4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10781,6 +10781,12 @@ struct sched_change_ctx *sched_change_begin(struct task_struct *p, unsigned int
 	struct sched_change_ctx *ctx = this_cpu_ptr(&sched_change_ctx);
 	struct rq *rq = task_rq(p);
 
+	/*
+	 * Must exclusively use matched flags since this is both dequeue and
+	 * enqueue.
+	 */
+	WARN_ON_ONCE(flags & 0xFFFF0000);
+
 	lockdep_assert_rq_held(rq);
 
 	if (!(flags & DEQUEUE_NOCLOCK)) {