Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756847AbcCDASN (ORCPT ); Thu, 3 Mar 2016 19:18:13 -0500 Received: from mail-ob0-f172.google.com ([209.85.214.172]:33276 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751539AbcCDASL (ORCPT ); Thu, 3 Mar 2016 19:18:11 -0500 MIME-Version: 1.0 In-Reply-To: <87wppj4198.fsf@rasmusvillemoes.dk> References: <87wppj4198.fsf@rasmusvillemoes.dk> From: Andy Lutomirski Date: Thu, 3 Mar 2016 16:17:51 -0800 Message-ID: Subject: Re: soft lockup when passing vvar address to write(2) To: Rasmus Villemoes Cc: Andy Lutomirski , "linux-kernel@vger.kernel.org" , X86 ML 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: 756 Lines: 19 On Thu, Mar 3, 2016 at 2:58 PM, Rasmus Villemoes wrote: > Looking up the vvar mapping and dumping its contents sometimes results > in a soft lockup. On 4.5-rc6+ (master from earlier today) it seems to be > a little harder to trigger than on the 4.2something Ubuntu kernel I > first saw it on, but in both cases it's easy to reproduce (10s of > iterations at most) by running the below program in a loop. > I can't reproduce this. Do you have a .config or some other hint? Can you also give me the contents of /sys/devices/system/clocksource/clocksource0/current_clocksource and the output from 'dmesg |grep -i hpet'? And is this in a VM or on a native boot? My best guess is that you have a particularly buggy hpet. --Andy