From owner-freebsd-threads@FreeBSD.ORG Fri Sep 14 01:47:38 2007 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8148116A418 for ; Fri, 14 Sep 2007 01:47:38 +0000 (UTC) (envelope-from davidxu@freebsd.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 6BFE613C458; Fri, 14 Sep 2007 01:47:38 +0000 (UTC) (envelope-from davidxu@freebsd.org) Received: from [127.0.0.1] (root@localhost [127.0.0.1]) by freefall.freebsd.org (8.14.1/8.14.1) with ESMTP id l8E1lZwW043755; Fri, 14 Sep 2007 01:47:37 GMT (envelope-from davidxu@freebsd.org) Message-ID: <46E9E867.7030909@freebsd.org> Date: Fri, 14 Sep 2007 09:48:23 +0800 From: David Xu User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.13) Gecko/20070516 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Joe Peterson References: <46E9CBC8.3060906@gentoo.org> In-Reply-To: <46E9CBC8.3060906@gentoo.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-threads@freebsd.org Subject: Re: Segfault when mapping libpthread -> libthr X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Sep 2007 01:47:38 -0000 Joe Peterson wrote: > I am a developer on the Gentoo/FreeBSD project. For those who don't > know, this is basically porting the gentoo tools, package installer, > init stuff, etc. to FreeBSD (kernel and userland). I have been > investigating a rather challenging crash in libthr with 6.2. We have > libpthread and libc_r mapped to libthr (as I understand this is the > default for 7.0). I doubt, however, that this issue is gentoo-related, > since the system is essentially FreeBSD, but I cannot be 100% sure, of > course. > > In particular, ImageMagick's "mogrify" utility is segfaulting. I have > traced this down to the fact that _cur_thread() returns a different > address after many mutex locks in pthread (using the libthr library). > This causes the mutex linked list in the thread to have zero pointers > for first/last, and the crash results. I have verified with a > ImageMagick developer that mogrfiy is using only one thread, so this > should never happen. > > Another clue is that the curthread address seems to change sometime > shortly before __error (in libthr/sys/thr_error.c) gets called. > > I now am not sure how to debug this further. The address returned by > _get_curthread() is close, but slightly higher (by typically 0x100) than > the original thread's address. > > I can reproduce the problem faithfully on two of my systems, so if any > of this rings a bell, or if you have any suggestions for things to try > on my end, I'd be extremely appreciative! > > -Joe you may try revision 1.3 of http://www.freebsd.org/cgi/cvsweb.cgi/src/lib/libthr/sys/thr_error.c to see if the problem goes away. David Xu