From nobody Wed Feb 11 10:52:12 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5205C77B7D for ; Wed, 10 May 2023 07:28:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235895AbjEJH2y (ORCPT ); Wed, 10 May 2023 03:28:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235830AbjEJH2v (ORCPT ); Wed, 10 May 2023 03:28:51 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7C287AA7 for ; Wed, 10 May 2023 00:28:37 -0700 (PDT) From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1683703716; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PQ3NXQMtig0Ydn+DZ27wQ54KKOjUtVfs2xndfW98O6U=; b=D1z8D7w3JzNIOBDodikGpgba/haCLy1TxmxP/1wSCOZKJuKDVD8q6m1tAVemn7SY1VMWfX 6inJI1GFRSek4B7U+lxGZiw87qltifNke3JPTbMUysJgKWHviXMFJyHEtcUVC+7ILLMW9h nmo1GduNR6p9ELH1LAs8wPS+1y1Zy4qGBabcXVgtpq96Pi5Rm6DGeX8uMQFlHKifa2b268 qMRrYVXrF9NhOdDFIgse2Mhu5ZVo0Qtzo+AeyfIiUILGHXgxGjQmSVsjpP++ZaEKDKBBCq Q6gSE/tTo6gXH2v+zwCnuTMQQbfceTvYFc7Sg815OQlx8zkCGzNMBQ5jMKOM4A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1683703716; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PQ3NXQMtig0Ydn+DZ27wQ54KKOjUtVfs2xndfW98O6U=; b=gouTsahUwW0QIcMnc5t/uebABITaHYIEOsA+7sqa8xzzd0gbx4fXMQfK0n2Cp3y0Ht/nMd AFCfNmzT2tNM68Aw== To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , John Stultz , Thomas Gleixner , Eric Dumazet , "Rafael J . Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Frederic Weisbecker , Rik van Riel , Steven Rostedt , Sebastian Siewior , Giovanni Gherdovich , Lukasz Luba , "Gautham R . Shenoy" , Anna-Maria Behnsen , Frederic Weisbecker Subject: [PATCH v6 01/21] tick-sched: Warn when next tick seems to be in the past Date: Wed, 10 May 2023 09:27:57 +0200 Message-Id: <20230510072817.116056-2-anna-maria@linutronix.de> In-Reply-To: <20230510072817.116056-1-anna-maria@linutronix.de> References: <20230510072817.116056-1-anna-maria@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When the next tick is in the past, the delta between basemono and the next tick gets negativ. But the next tick should never be in the past. The negative effect of a wrong next tick might be a stop of the tick and timers might expire late. To prevent expensive debugging when changing underlying code, add a WARN_ON_ONCE into this code path. Signed-off-by: Anna-Maria Behnsen Reviewed-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker --- kernel/time/tick-sched.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 52254679ec48..62836490ba4d 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -831,6 +831,8 @@ static ktime_t tick_nohz_next_event(struct tick_sched *= ts, int cpu) * If the tick is due in the next period, keep it ticking or * force prod the timer. */ + WARN_ON_ONCE(basemono > next_tick); + delta =3D next_tick - basemono; if (delta <=3D (u64)TICK_NSEC) { /* --=20 2.30.2