Re: [PATCH 05/12] sched: Move sched_class::prio_changed() into the change pattern

From: Pierre Gondois

Date: Tue Jan 13 2026 - 08:09:12 EST


On 1/13/26 12:56, Peter Zijlstra wrote:
On Tue, Jan 13, 2026 at 12:53:09PM +0100, Peter Zijlstra wrote:
On Tue, Jan 13, 2026 at 04:35:02PM +0530, K Prateek Nayak wrote:

Does enabling WARN_DOUBLE_CLOCK warn of a double clock update before
hitting this warning?
setup_new_dl_entity() -> update_rq_clock() seems like it will trip that
in this case.
Something like so to fix: 9f239df55546 ("sched/deadline: Initialize dl_servers after SMP")


--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -752,8 +752,6 @@ static inline void setup_new_dl_entity(s
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
struct rq *rq = rq_of_dl_rq(dl_rq);
- update_rq_clock(rq);
-
WARN_ON(is_dl_boosted(dl_se));
WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
@@ -1834,6 +1832,7 @@ void sched_init_dl_servers(void)
rq = cpu_rq(cpu);
guard(rq_lock_irq)(rq);
+ update_rq_clock(rq);
dl_se = &rq->fair_server;
Yes right, enabling WARN_DOUBLE_CLOCK detects the double clock update and this fixes it.