From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: INFO: rcu_preempt detected stalls on CPUs/tasks Date: Thu, 14 Jul 2016 17:27:03 +0200 Message-ID: <20160714152703.GA12152@linutronix.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: "linux-rt-users@vger.kernel.org" To: Roosen Henri Return-path: Received: from www.linutronix.de ([62.245.132.108]:45109 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751455AbcGNP1G (ORCPT ); Thu, 14 Jul 2016 11:27:06 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: * Roosen Henri | 2016-06-30 16:05:09 [+0000]: >Hi, Hi, >I just got an info-backtrace while running cyclictest on an iMX28 with kernel 4.1.27-rt30. >This resulted in a latency spike (i'm not sure whether caused by the trace dumping). >Can anyone share some info on this and what to do to prevent the cause of this info-trace? Did you do anything else besides starting cyclictest? RCU was somehow blocked and did not make any progress. This might if a task in an RCU-read section got preempted for long time _or_ is active in that section over a very long time. More information can be found at https://www.kernel.org/doc/Documentation/RCU/stallwarn.txt Sebastian