From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967157AbcA1CP4 (ORCPT ); Wed, 27 Jan 2016 21:15:56 -0500 Received: from mail-pf0-f170.google.com ([209.85.192.170]:35769 "EHLO mail-pf0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966482AbcA1CPz (ORCPT ); Wed, 27 Jan 2016 21:15:55 -0500 Date: Thu, 28 Jan 2016 07:45:53 +0530 From: Viresh Kumar To: "Rafael J. Wysocki" Cc: linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, "# v4 . 2+" , Juri Lelli , open list Subject: Re: [PATCH] cpufreq: Fix NULL reference crash while accessing policy->governor_data Message-ID: <20160128021553.GC3935@vireshk> References: <1297c8fc8135f8b5359f9c49d220a939c0ee640e.1453741314.git.viresh.kumar@linaro.org> <3004241.yqvZmcL5vE@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3004241.yqvZmcL5vE@vostro.rjw.lan> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27-01-16, 23:54, Rafael J. Wysocki wrote: > So I've applied this, but I'm not sure it is sufficient yet. At least, this solves the crash Juri was hitting on a multi cluster box. > Have you double checked whether or not stuff cannot be reordered by > the CPU and/or the compiler and no additional memory barriers are needed? I don't think CPU will reorder things before a function call. It can reorder lines, which CPU thinks aren't related but it can't assume the same in this case. We have tons of code like this. @Juri: What do you say? -- viresh