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[2a02:3100:b305:2001:39fa:3d24:821a:4eae]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a0394e6c5asm281196795e9.2.2026.10.05.11.58.31 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 05 Oct 2026 11:58:33 -0700 (PDT) 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 v4 6/6] sched/core: Pause KCOV in wake_up_new_task() Date: Mon, 5 Oct 2026 20:58:03 +0200 Message-Id: <20261005185803.39170-7-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20261005185803.39170-1-kmehltretter@gmail.com> References: <20261005185803.39170-1-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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. Assisted-by: LLM 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 f19221282278..888460c97952 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4969,6 +4969,9 @@ 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. */ + guard(kcov_pause)(); + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); WRITE_ONCE(p->__state, TASK_RUNNING); /* -- 2.53.0