From nobody Sat Feb 7 08:43:54 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 111E91FBF for ; Wed, 21 Feb 2024 01:18:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708478298; cv=none; b=BkBi8UUW6ehOPQVbf6bckzAM5SI1GO/RdzA4uPrVkweYR1/5zYplkwjMV+YPHnxOUK0UvYuYGE7aN9DA7H8HshlB7ORX+VEkCLWPknSek4qJvrrHU2KmEMSWLg63z8mvNGHaVKnVpUJBBUjksk2CK0YCujHYA2B71ks7H6BISW4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708478298; c=relaxed/simple; bh=iEm71T6gEzS4iOJpNt3i4b/pIzZx55+2d+g9DQ+IKVg=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=XGefX2ef3KNQCxfFWVz/8Ls94xF2PFwd8JanZaXB+NidI9s1faAc8OqHVQTGcDp7JaWzAg+LcBiCHCY4grN2euIHv0uzfwDUH+qXDPqyoThrVCdCW2ZcK0yNzkwUrHeF6ObHgOPHFlZ0X0nErCre1ySZpKFIO5nImFYKjsuoMSw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99760C43390; Wed, 21 Feb 2024 01:18:16 +0000 (UTC) Date: Tue, 20 Feb 2024 20:20:02 -0500 From: Steven Rostedt To: LKML Cc: Ingo Molnar , Peter Zijlstra , Masami Hiramatsu , Mathieu Desnoyers , Daniel Bristot de Oliveira , Vincent Guittot , Juri Lelli Subject: [PATCH] sched/clock: Make local_clock() notrace Message-ID: <20240220202002.38fec245@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" The "perf" clock in /sys/kernel/tracing/trace_clock enables local_clock(), where on machines that have CONFIG_HAVE_UNSTABLE_SCHED_CLOCK set is a normal function. This function can be traced. I found that enabling the "perf" clock on some debug configs and running function tracer can live lock the machine. That is, it goes so slow that nothing moves forward. Cc: stable@vger.kernel.org Fixes: fb7d4948c4da2 ("sched/clock: Provide local_clock_noinstr()") Signed-off-by: Steven Rostedt (Google) --- kernel/sched/clock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 3c6193de9cde..af8b698dee8c 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -308,7 +308,7 @@ noinstr u64 local_clock_noinstr(void) return clock; } =20 -u64 local_clock(void) +notrace u64 local_clock(void) { u64 now; preempt_disable_notrace(); --=20 2.43.0