From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: RCU stall on panda Date: Tue, 13 May 2014 08:32:20 -0700 Message-ID: <20140513153220.GC16837@atomide.com> References: <53675C5F.10509@linaro.org> <20140505180617.GM8754@linux.vnet.ibm.com> <20140512212102.GF5668@atomide.com> <5371BD69.8010600@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:10239 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751991AbaEMPcb (ORCPT ); Tue, 13 May 2014 11:32:31 -0400 Content-Disposition: inline In-Reply-To: <5371BD69.8010600@linaro.org> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Alex Shi Cc: "Paul E. McKenney" , "naresh.kamboju@linaro.org Kamboju" , Daniel Lezcano , Linaro Kernel , LAK , Mark Brown , linux-omap@vger.kernel.org * Alex Shi [140512 23:37]: > On 05/13/2014 05:21 AM, Tony Lindgren wrote: > > * Paul E. McKenney [140505 11:11]: > >> On Mon, May 05, 2014 at 05:39:43PM +0800, Alex Shi wrote: > >>> I keep seeing the RCU stall problem on panda board from 3.10 kernel to latest upstream kernel > >>> and google find some one report it before: https://lkml.org/lkml/2012/9/20/519 > >>> > >>> Is it the hardware issue or a real software problem? > >> > >> I cannot distinguish between hardware and software from the trace below, > >> but given that you are also seeing a soft lockup, either way you do > >> appear to have a real problem as opposed to an RCU CPU stall warning > >> false positive. > > > > Looks like you have CPU_IDLE enabled on panda. Hangs with current linux > > next with CPU_IDLE are currently being discussed on the linux-omap list > > in thread "omap4-panda-es boot issues with v3.15-rc4" > > > > I've seen occasional system hangs, and I've also noticed that doing > > ctrl-a-f h or ctrl-a-f l for sysrq backtrace can unlock the system > > producing similar errors to the below. > > > > Thanks a lot for the info. > In fact, the oops keeps in upstream kernel from 3.10 to latest. Care to test if the revert of commit cb7094 Santosh posted as "[PATCH] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled" solves the problem for you? Regards, Tony From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Tue, 13 May 2014 08:32:20 -0700 Subject: RCU stall on panda In-Reply-To: <5371BD69.8010600@linaro.org> References: <53675C5F.10509@linaro.org> <20140505180617.GM8754@linux.vnet.ibm.com> <20140512212102.GF5668@atomide.com> <5371BD69.8010600@linaro.org> Message-ID: <20140513153220.GC16837@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Alex Shi [140512 23:37]: > On 05/13/2014 05:21 AM, Tony Lindgren wrote: > > * Paul E. McKenney [140505 11:11]: > >> On Mon, May 05, 2014 at 05:39:43PM +0800, Alex Shi wrote: > >>> I keep seeing the RCU stall problem on panda board from 3.10 kernel to latest upstream kernel > >>> and google find some one report it before: https://lkml.org/lkml/2012/9/20/519 > >>> > >>> Is it the hardware issue or a real software problem? > >> > >> I cannot distinguish between hardware and software from the trace below, > >> but given that you are also seeing a soft lockup, either way you do > >> appear to have a real problem as opposed to an RCU CPU stall warning > >> false positive. > > > > Looks like you have CPU_IDLE enabled on panda. Hangs with current linux > > next with CPU_IDLE are currently being discussed on the linux-omap list > > in thread "omap4-panda-es boot issues with v3.15-rc4" > > > > I've seen occasional system hangs, and I've also noticed that doing > > ctrl-a-f h or ctrl-a-f l for sysrq backtrace can unlock the system > > producing similar errors to the below. > > > > Thanks a lot for the info. > In fact, the oops keeps in upstream kernel from 3.10 to latest. Care to test if the revert of commit cb7094 Santosh posted as "[PATCH] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled" solves the problem for you? Regards, Tony