Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030923AbcCQOFS (ORCPT ); Thu, 17 Mar 2016 10:05:18 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:63067 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753154AbcCQOFO (ORCPT ); Thu, 17 Mar 2016 10:05:14 -0400 From: "Rafael J. Wysocki" To: Josh Boyer , Srinivas Pandruvada , Philippe Longepe Cc: Len Brown , Viresh Kumar , Linux PM list , "Linux-Kernel@Vger. Kernel. Org" Subject: Re: intel_pstate oopses and lockdep report with Linux v4.5-1822-g63e30271b04c Date: Thu, 17 Mar 2016 15:07:16 +0100 Message-ID: <1704778.QLUl50G1uZ@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.5.0-rc1+; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1467 Lines: 44 On Thursday, March 17, 2016 09:02:29 AM Josh Boyer wrote: > Hello, Hi, > I have an Intel Atom based NUC that is producing the following > backtraces on boot of Linus' tree as of last evening. This does not > happen with a tree with top level commit 271ecc5253e2, but does happen > when using the tree mentioned in the subject with top level commit > 63e30271b04c. > > The first backtrace appears to be a warning because the intel_pstate > driver is calling wrmsrl_on_cpu when interrupts are disabled? Not > sure on that one. > > The second backtrace is a lockdep report. Both are from the same boot. OK, thanks for the report. Can you please try the patch below? I'm actually unsure if we can do that safely in general for Atom because of the initialization, but that's what Core does anyway. Srinivas, Philippe, why exactly do we need the wrmsrl_on_cpu() in atom_set_pstate()? core_set_pstate() uses wrmsrl() and seems to be doing fine. --- drivers/cpufreq/intel_pstate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -587,7 +587,7 @@ static void atom_set_pstate(struct cpuda val |= vid; - wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val); + wrmsrl(MSR_IA32_PERF_CTL, val); } static int silvermont_get_scaling(void)