[PATCH 7/9] sched/core_sched: defer WARN console output under rq->lock

[Rik van Riel]

Convert the WARN*() calls that run under rq->lock or ->pi_lock to the
SCHED_WARN*() variants, so their console output is deferred to irq_work
instead of being emitted synchronously (which can deadlock via
console_unlock() -> up(&console_sem) -> try_to_wake_up() while the lock
is held).

This should prevent a deadlock if these warnings fire with a legacy
or boot console configured.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
Assisted-by: Claude:claude-opus-4-8
---
 kernel/sched/core_sched.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
index 43e0bde3038e..e39fb8935ef7 100644
--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -67,7 +67,7 @@ static unsigned long sched_core_update_cookie(struct task_struct *p,
 	 * a cookie until after we've removed it, we must have core scheduling
 	 * enabled here.
 	 */
-	WARN_ON_ONCE((p->core_cookie || cookie) && !sched_core_enabled(rq));
+	SCHED_WARN_ON_ONCE((p->core_cookie || cookie) && !sched_core_enabled(rq));
 
 	if (sched_core_enqueued(p))
 		sched_core_dequeue(rq, p, DEQUEUE_SAVE);
@@ -249,7 +249,7 @@ void __sched_core_account_forceidle(struct rq *rq)
 
 	lockdep_assert_rq_held(rq);
 
-	WARN_ON_ONCE(!rq->core->core_forceidle_count);
+	SCHED_WARN_ON_ONCE(!rq->core->core_forceidle_count);
 
 	if (rq->core->core_forceidle_start == 0)
 		return;
@@ -260,7 +260,7 @@ void __sched_core_account_forceidle(struct rq *rq)
 
 	rq->core->core_forceidle_start = now;
 
-	if (WARN_ON_ONCE(!rq->core->core_forceidle_occupation)) {
+	if (SCHED_WARN_ON_ONCE(!rq->core->core_forceidle_occupation)) {
 		/* can't be forced idle without a running task */
 	} else if (rq->core->core_forceidle_count > 1 ||
 		   rq->core->core_forceidle_occupation > 1) {
-- 
2.53.0-Meta