From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 9AE6525B081 for ; Thu, 9 Jul 2026 13:38:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783604316; cv=none; b=G5gWHBn96J4h6g2zW+fgdkdN4bnIzlenbyFs7UHVEx8RE2p8DEVYDHdCcxeJcP8SXo3TrxXnF+yTbh77lFsI/e+1nYdyhZevuS8gSLfJUA5x1omAMZbB5R0ToIS9fc1uKFraMDF0/KwrKPqDJX2veC2MmkcT8Fjys/eDo333psY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783604316; c=relaxed/simple; bh=qxSmOigsMJ1N95K1AV6+UK74k1iC7RZn31Xftg/IyEs=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References: Content-Type:MIME-Version; b=iEx+aYc7B1xm7GPp1MBpU6cI8owbJsKGJsLQ0zcc85L2oWq4IhfKySfBMQTaycv+xrwNhIxeVf5fFcH/UOwyhs+tZFrtHRdCderYuA7QA+2bko4MaDKE5Q6F+xK/LubVLQEyYzr2yJfqltKQRLSGfxKUBt6q34UCH0jF5XKHfH8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=casper.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=J4GxLE+p; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=casper.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="J4GxLE+p" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:To:From:Subject:Message-ID:Sender: Reply-To:Cc:Content-ID:Content-Description; bh=qxSmOigsMJ1N95K1AV6+UK74k1iC7RZn31Xftg/IyEs=; b=J4GxLE+pqaj8SLGbj0zhrDEMcT pcpNtVax4q5A6/G7SfobA2Ut6B9y1TqhD5j+E9fpiz+RPZdc+rt1ETEqnFWFKGAzZ8CoXOFY8p2uI PgSnUIlASL4xhpXHpkUfWwZELm0BsV33EdXy1xytRisI4ck+b1jMfIfG5SwbxobnGRKgi2OtqUQKZ WOPoOMuXjlHJVvPTib/hROXTZsQPyKRLHYevfwXa4wDACcfi2sO/ZYiPp9G7qhiE2Y+HK4KfJcOdc e+lZCn9KFNMeiSZWM34yAfc2qYRVnN6yOSdXN1WMGQWVMj2UMlbhkxqxeFus+fk9OLQRbyDTFjOhL TLft4f7w==; Received: from [2001:8b0:10b:5:bad8:d14c:3672:7028] (helo=u09cd745991455d.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1whox7-00000004uLr-1jg6; Thu, 09 Jul 2026 13:38:09 +0000 Message-ID: Subject: Re: [PATCH v7 3/7] timekeeping: Account for clocksource tick quantisation via NTP From: David Woodhouse To: Marek Szyprowski , Richard Cochran , Wen Gu , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , John Stultz , Thomas Gleixner , Stephen Boyd , Anna-Maria Behnsen , Frederic Weisbecker , Shuah Khan , Peter Zijlstra , Thomas =?ISO-8859-1?Q?Wei=DFschuh?= , Arnd Bergmann , Miroslav Lichvar , Julien Ridoux , Ryan Luu , linux-kernel@vger.kernel.org Date: Thu, 09 Jul 2026 14:38:08 +0100 In-Reply-To: References: <20260621220051.1030462-1-dwmw2@infradead.org> <20260621220051.1030462-4-dwmw2@infradead.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.3-0ubuntu1~ppa9~24.04 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html On Thu, 2026-07-09 at 14:56 +0200, Marek Szyprowski wrote: >=20 > This patch landed yesterday in linux-next as commit e8bf3955dc2f > ("timekeeping: Account for clocksource tick quantisation via NTP"). > In my tests I found that it breaks booting Raspberry Pi 3B and Pi 4B > boards in ARM 32bit mode with quite old (Debian 10) userspace. Booting > freezes just before getting a getty login prompt and no more kernel > or userspace messages are observed. If I start with init=3D/bin/bash in > kernel cmdline and then wait a while and do "exec /sbin/init" I get > the following additional kernel message: >=20 > [=C2=A0 186.867605] Adjusting arch_sys_counter more than 11% (12136 vs 34= 4864995) >=20 > then booting freezes again before getting getty prompt. >=20 > I can do some more tests, just let me know what will help debugging this > issue. Other ARM 32bit machines I have work fine with this patch. >=20 > Reverting subject together with its dependencies on top of linux-next=C2= =A0 > fixes the issue. Thank you. I'm confused at this, because it's basically adding the *same* delta to the tick, just in a different place. While I go and frown at the maths a bit more... would you mind testing if *just* the change from TK_CLOCK_WAS_SET to TK_UPDATE_ALL in timekeeping_init() is the culprit? Could you add some pr_info() of xtime_remainder and cs_tick_adj (in the before vs. after cases)?