Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758256Ab0FIUrf (ORCPT ); Wed, 9 Jun 2010 16:47:35 -0400 Received: from www.tglx.de ([62.245.132.106]:50890 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756739Ab0FIUre (ORCPT ); Wed, 9 Jun 2010 16:47:34 -0400 Date: Wed, 9 Jun 2010 22:47:23 +0200 (CEST) From: Thomas Gleixner To: Matthew Garrett cc: =?ISO-8859-15?Q?Ortwin_Gl=FCck?= , linux-kernel@vger.kernel.org Subject: Re: freeze when strace X In-Reply-To: <20100609200610.GA27536@srcf.ucam.org> Message-ID: References: <4C0FDF9F.9070000@odi.ch> <20100609195228.GA27088@srcf.ucam.org> <4C0FF34D.6090800@odi.ch> <20100609200610.GA27536@srcf.ucam.org> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-846436559-1276116444=:2933" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1475 Lines: 37 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-846436559-1276116444=:2933 Content-Type: TEXT/PLAIN; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT On Wed, 9 Jun 2010, Matthew Garrett wrote: > On Wed, Jun 09, 2010 at 10:02:21PM +0200, Ortwin Gl?ck wrote: > > On 09.06.2010 21:52, Matthew Garrett wrote: > > > Just to make sure, you're not trying to strace X from within X, are you? > > > > Oh... now that you mention it... Is that a silly thing to do? > > strace X from a different terminal works fine :-) > > > > But freezing the system because of that? I mean an error message, log, anything > > would be "nice". > > strace needs to output text via X, which generates output which needs to > be output via X... and you'll tend to deadlock. If X is holding any > interesting kernel locks at that point then it wouldn't surprise me if > the machine ends up dead. Nothing to do with kernel locks. strace hooks into the syscall and intercepts the data, so X is stopped at that point. Now try to send output to a program which you stopped yourself :) Thanks, tglx --8323328-846436559-1276116444=:2933-- -- 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/