linux-kernel - [tip: sched/core] sched: Mandate shared flags for sched

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Message-ID: <176060720339.709179.11411110575937690476.tip-bot2@tip-bot2>
Date: Thu, 16 Oct 2025 09:33:23 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Shrikanth Hegde <sshegde@...ux.ibm.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Mandate shared flags for sched_change

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

Commit-ID:     73ec89a1ce4bce98f74b6520a95e64cd9986aae5
Gitweb:        https://git.kernel.org/tip/73ec89a1ce4bce98f74b6520a95e64cd9986aae5
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 06 Oct 2025 20:12:34 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 16 Oct 2025 11:13:54 +02:00

sched: Mandate shared flags for sched_change

Shrikanth noted that sched_change pattern relies on using shared
flags.

Suggested-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3d5659f..e2199e4 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)) {