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[2a02:3100:b149:1401:90c6:65b4:35d:1e3d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b7e3279f9csm65132675e9.8.2026.11.07.05.17.34 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sat, 07 Nov 2026 05:17:35 -0800 (PST) From: Karl Mehltretter To: Andrew Morton Cc: Karl Mehltretter , Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Marco Elver , Bradley Morgan , Anna-Maria Behnsen , Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Sebastian Andrzej Siewior , Clark Williams , linux-rt-devel@lists.linux.dev, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Subject: [PATCH v5 6/6] sched/core: Pause KCOV in wake_up_new_task() Date: Sat, 7 Nov 2026 14:17:10 +0100 Message-Id: <20261107131710.89264-7-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20261107131710.89264-1-kmehltretter@gmail.com> References: <20261107131710.89264-1-kmehltretter@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit wake_up_new_task() is built without KCOV instrumentation, but CPU selection and enqueue call helpers instrumented with KCOV. During a KCOV-enabled fork, they can record scheduler, hrtimer and clockevent coverage into the parent. The paths depend on runqueue and CPU state, so coverage varies between identical forks. Pause KCOV for the whole function, extending the scheduler exclusion to new-task wakeups. Signed-off-by: Karl Mehltretter --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4bd0d5736ccf..a63bd78ce5d7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5019,6 +5019,9 @@ void wake_up_new_task(struct task_struct *p) struct rq *rq; int wake_flags = WF_FORK; + /* Callees instrumented with KCOV would leak coverage into current. */ + kcov_pause_scope(); + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); WRITE_ONCE(p->__state, TASK_RUNNING); /* -- 2.39.5