Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755382Ab3C1DNs (ORCPT ); Wed, 27 Mar 2013 23:13:48 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:34844 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755021Ab3C1DNq (ORCPT ); Wed, 27 Mar 2013 23:13:46 -0400 MIME-Version: 1.0 In-Reply-To: <5153B03E.2050201@gmail.com> References: <5153B03E.2050201@gmail.com> Date: Wed, 27 Mar 2013 23:13:45 -0400 Message-ID: Subject: Re: intel_pstate_timer_func divide by zero oops From: Parag Warudkar To: Dirk Brandewie Cc: "Rafael J. Wysocki" , cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, LKML , Linus Torvalds Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 37 On Wed, Mar 27, 2013 at 10:51 PM, Dirk Brandewie wrote: > > Is there any way to capture the beginning of this trace? I tried but since the oops scrolls fast followed by a hard freeze, I wasn't able to capture it completely. May be I can try netconsole and see if that helps. > > pid_param_set() is on the stack which means that something is changing > the debugfs parameters or the stack is FUBAR. > I somehow doubt the stack is messed up as the call traces are always identical. (pid_param_set() seems to be in first trace as well.) > > I don't see how duration_us can be zero unless somehow I am getting > back-to-back > timer callbacks which seems unlikely since the timer is not re-armed until > the timer function is about to return and the driver has done all its work > for the sample period Do the two oops with common call stack suggest back to back callbacks? I will add some debugging checks tomorrow to see what is going on. But sounds like a minimal fix would be to guard against callbacks in quick succession? i.e. return from sample if ktime_us_delta(now, cpu->prev_sample) is zero? Thanks, Parag -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/