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[82.127.110.121]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-482e27aa050sm8332627f8f.12.2026.08.27.04.40.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Aug 2026 04:40:29 -0700 (PDT) From: Amin Gattout Date: Thu, 27 Aug 2026 13:40:14 +0200 Subject: [PATCH] sched/core: Convert remaining BUG_ON() instances to WARN_ON_ONCE() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260827-warn_instead_bug-v1-1-b515c0f74b89@gmail.com> X-B4-Tracking: v=1; b=H4sIAB0ikGoC/yXMTQ5AMBBA4avIrDWhElpXEZGqwViUdPwl4u6K5 bd47wJGT8hQRhd43IlpdgFpHIEdjRtQUBcMMpF5omQhDuNdQ45XNF3TboOwGo3OlFZpZiFki8e ezm9Z1b95aye06/uB+34Am2jj/HQAAAA= X-Change-ID: 20260827-warn_instead_bug-c9ea9389813c To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak Cc: linux-kernel@vger.kernel.org, Amin Gattout X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787830828; l=3492; i=amin.gattout@gmail.com; s=20260818; h=from:subject:message-id; bh=Y7RLpz0czh9Ikbzh4hZv7fGnKJReSQKdUwh6VSk0vok=; b=XV0c4BgQ8hfoeSwcOhLQ2wg/dNxcZJ+9PQxa+j6nGFXJQyImKgxUoe90xgefdLFfzDxX4J9cw lR2/GNXXIeMBiY+X7AWKL2QnoMEEmNoo+94sr9GpNLJgH5ftgmLzVCz X-Developer-Key: i=amin.gattout@gmail.com; a=ed25519; pk=MSIqDPkCOkwtyP8Fns1m+KFU9SgqoDl2mpLe18vL+hQ= Commit 09348d75a6ce ("sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE()") left a few BUG_ON() behind in core.c. Convert them as well. As described in Documentation/process/deprecated.rst, BUG_ON() crashes the system, which makes the failure harder to report and to debug, as the message often never reaches the console or the syslog. With WARN_ON_ONCE() the user gets a chance to see and report the problem instead, and system owners who do not want to keep running after an "impossible" condition can still set panic_on_warn. Signed-off-by: Amin Gattout --- Follow-up to commit 09348d75a6ce which converted the scheduler BUG_ON() instances to WARN_ON_ONCE() but left a few behind in core.c. Build tested on arm64 with CONFIG_NO_HZ_FULL and CONFIG_SCHED_CLASS_EXT enabled so that every converted site is compiled. --- kernel/sched/core.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f78275192036..bab74b4f0dd6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5949,7 +5949,7 @@ static void sched_tick_stop(int cpu) int __init sched_tick_offload_init(void) { tick_work_cpu =3D alloc_percpu(struct tick_work); - BUG_ON(!tick_work_cpu); + WARN_ON_ONCE(!tick_work_cpu); return 0; } =20 @@ -7582,7 +7582,7 @@ asmlinkage __visible void __sched preempt_schedule_ir= q(void) enum ctx_state prev_state; =20 /* Catch callers which need to be fixed */ - BUG_ON(preempt_count() || !irqs_disabled()); + WARN_ON_ONCE(preempt_count() || !irqs_disabled()); =20 prev_state =3D exception_enter(); =20 @@ -8619,7 +8619,7 @@ static inline void sched_set_rq_online(struct rq *rq,= int cpu) =20 rq_lock_irqsave(rq, &rf); if (rq->rd) { - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); + WARN_ON_ONCE(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_online(rq); } rq_unlock_irqrestore(rq, &rf); @@ -8631,7 +8631,7 @@ static inline void sched_set_rq_offline(struct rq *rq= , int cpu) =20 rq_lock_irqsave(rq, &rf); if (rq->rd) { - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); + WARN_ON_ONCE(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_offline(rq); } rq_unlock_irqrestore(rq, &rf); @@ -8954,13 +8954,13 @@ void __init sched_init(void) int i; =20 /* Make sure the linker didn't screw up */ - BUG_ON(!sched_class_above(&stop_sched_class, &dl_sched_class)); - BUG_ON(!sched_class_above(&dl_sched_class, &rt_sched_class)); - BUG_ON(!sched_class_above(&rt_sched_class, &fair_sched_class)); - BUG_ON(!sched_class_above(&fair_sched_class, &idle_sched_class)); + WARN_ON_ONCE(!sched_class_above(&stop_sched_class, &dl_sched_class)); + WARN_ON_ONCE(!sched_class_above(&dl_sched_class, &rt_sched_class)); + WARN_ON_ONCE(!sched_class_above(&rt_sched_class, &fair_sched_class)); + WARN_ON_ONCE(!sched_class_above(&fair_sched_class, &idle_sched_class)); #ifdef CONFIG_SCHED_CLASS_EXT - BUG_ON(!sched_class_above(&fair_sched_class, &ext_sched_class)); - BUG_ON(!sched_class_above(&ext_sched_class, &idle_sched_class)); + WARN_ON_ONCE(!sched_class_above(&fair_sched_class, &ext_sched_class)); + WARN_ON_ONCE(!sched_class_above(&ext_sched_class, &idle_sched_class)); #endif =20 wait_bit_init(); --- base-commit: 73e3f0710014fe6d4ed98cfc02292f6121db7558 change-id: 20260827-warn_instead_bug-c9ea9389813c Best regards, -- =20 Amin Gattout