From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753467AbbKZSJo (ORCPT <rfc822;w@1wt.eu>);
	Thu, 26 Nov 2015 13:09:44 -0500
Received: from mail.skyhub.de ([78.46.96.112]:59516 "EHLO mail.skyhub.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753446AbbKZSJk (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 26 Nov 2015 13:09:40 -0500
Date: Thu, 26 Nov 2015 19:09:34 +0100
From: Borislav Petkov <bp@alien8.de>
To: Doug Smythies <dsmythies@telus.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: As of kernel 4.4-rc1 segmentation fault if msr module not
 loaded. [REGRESSION][BISECTED]
Message-ID: <20151126180934.GB18183@pd.tnic>
References: <000301d12867$19ba3030$4d2e9090$@net>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <000301d12867$19ba3030$4d2e9090$@net>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Nov 26, 2015 at 08:25:43AM -0800, Doug Smythies wrote:
> Hi,
> 
> This might be considered a minor issue, but I submit my
> findings anyhow.
> 
> In some distros, the msr module is not loaded by default.
> (I guess not built in by default, would be more correct.)
> I often forget to load it before using "rdmsr" or "wrmsr".
> It was never an issue before, but as of Kernel 4.4-rc1
> it causes a segmentation fault crash. Example:
> 
> # rdmsr -a 0x19a
> Segmentation fault (core dumped)

You can either cherrypick

http://git.kernel.org/tip/2d5be37d686c4dae8e60d20283d6f44ac2c44f65

or wait until it trickles upwards to Linus, most likely -rc3.

Thanks for the report. Good to know what else broke.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.