From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#39962: 27.0.90; Crash in Emacs 27.0.90 Date: Tue, 17 Mar 2020 13:59:04 -0700 Organization: UCLA Computer Science Department Message-ID: <2b2fc990-2917-7970-d88b-7708dbaa48be@cs.ucla.edu> References: <24162.58107.725366.668639@cochabamba.vanoostrum.org> <83y2s48yn7.fsf@gnu.org> <83zhck6obg.fsf@gnu.org> <83r1xv73ze.fsf@gnu.org> <83imj5bdct.fsf@gnu.org> <83zhcff131.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="37137"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 Cc: 39962@debbugs.gnu.org, pipcet@gmail.com To: Eli Zaretskii , Pieter van Oostrum Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Tue Mar 17 22:00:22 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jEJK2-0009ZS-04 for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 17 Mar 2020 22:00:22 +0100 Original-Received: from localhost ([::1]:41270 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEJK0-0002EB-Vl for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 17 Mar 2020 17:00:21 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:49720) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEJJj-0002CL-Jr for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 17:00:04 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jEJJi-0003Kp-Gt for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 17:00:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:33628) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1jEJJi-0003KH-BT for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 17:00:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jEJJi-00088P-A4 for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 17:00:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Paul Eggert Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 17 Mar 2020 21:00:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 39962 X-GNU-PR-Package: emacs Original-Received: via spool by 39962-submit@debbugs.gnu.org id=B39962.158447875431160 (code B ref 39962); Tue, 17 Mar 2020 21:00:02 +0000 Original-Received: (at 39962) by debbugs.gnu.org; 17 Mar 2020 20:59:14 +0000 Original-Received: from localhost ([127.0.0.1]:39601 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jEJIw-00086W-62 for submit@debbugs.gnu.org; Tue, 17 Mar 2020 16:59:14 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:52620) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jEJIt-00086G-UT for 39962@debbugs.gnu.org; Tue, 17 Mar 2020 16:59:13 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 46B3E16008E; Tue, 17 Mar 2020 13:59:06 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id VFBJIjbODLDc; Tue, 17 Mar 2020 13:59:05 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 3CD70160091; Tue, 17 Mar 2020 13:59:05 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id a1AfrWDE2Eem; Tue, 17 Mar 2020 13:59:05 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 1055516008E; Tue, 17 Mar 2020 13:59:05 -0700 (PDT) In-Reply-To: <83zhcff131.fsf@gnu.org> Content-Language: en-US X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.51.188.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:177469 Archived-At: Although I haven't been following this in detail, I'd like to suggest trying a GDB watchpoint to find the bug. Watchpoints have been invaluable to me when I debug garbage-collector and other memory management issues. Say you have a repeatable way to make the problem happen. You discover that some random part of Emacs (you don't know what) has zapped the 'next' field of some data structure D to make it a null pointer. You want to find out who zapped it. To do that, first compute the address of the field you're interested in: (gdb) p &D->next You'll get a number like 0x16082a730. Then: (gdb) watch *(void *)0x16082a730 (gdb) run The last command re-runs Emacs, and should stop each time the memory location at 0x16082a730 changes. If you're lucky, this will be just a few times and you can figure out who's zapping D->next. If you're unlucky you can come up with a fancier watchpoint that may do the trick. (I'm using a plain 'watch' rather than a 'watch -l' in the example above, merely to keep things simple.)