From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Fix to long-standing crashes in GC Date: 19 May 2004 12:48:13 -0400 Sender: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Message-ID: References: <40A3BC23.8060000@math.ku.dk> <200405180013.i4I0Ddl15818@raven.dms.auburn.edu> NNTP-Posting-Host: deer.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1084997376 11927 80.91.224.253 (19 May 2004 20:09:36 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Wed, 19 May 2004 20:09:36 +0000 (UTC) Cc: Luc Teirlinck , rms@gnu.org, emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Wed May 19 22:09:24 2004 Return-path: Original-Received: from quimby.gnus.org ([80.91.224.244]) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1BQXNU-0000yL-00 for ; Wed, 19 May 2004 22:09:24 +0200 Original-Received: from monty-python.gnu.org ([199.232.76.173]) by quimby.gnus.org with esmtp (Exim 3.35 #1 (Debian)) id 1BQXNT-0007on-00 for ; Wed, 19 May 2004 22:09:24 +0200 Original-Received: from localhost ([127.0.0.1] helo=monty-python.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1BQXAS-0003zE-4n for emacs-devel@quimby.gnus.org; Wed, 19 May 2004 15:55:56 -0400 Original-Received: from list by monty-python.gnu.org with tmda-scanned (Exim 4.34) id 1BQX6L-00037o-RG for emacs-devel@gnu.org; Wed, 19 May 2004 15:51:42 -0400 Original-Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.34) id 1BQX5n-0002xt-G2 for emacs-devel@gnu.org; Wed, 19 May 2004 15:51:39 -0400 Original-Received: from [132.204.24.67] (helo=mercure.iro.umontreal.ca) by monty-python.gnu.org with esmtp (Exim 4.34) id 1BQUEs-0002Ac-NF; Wed, 19 May 2004 12:48:18 -0400 Original-Received: from asado.iro.umontreal.ca (asado.iro.umontreal.ca [132.204.24.84]) by mercure.iro.umontreal.ca (Postfix) with ESMTP id 3EDC821139; Wed, 19 May 2004 12:48:15 -0400 (EDT) Original-Received: by asado.iro.umontreal.ca (Postfix, from userid 20848) id DA9D68CA23; Wed, 19 May 2004 12:48:14 -0400 (EDT) Original-To: storm@cua.dk (Kim F. Storm) In-Reply-To: Original-Lines: 29 User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3.50 X-DIRO-MailScanner-Information: Please contact the ISP for more information X-DIRO-MailScanner: Found to be clean X-DIRO-MailScanner-SpamCheck: n'est pas un polluriel, SpamAssassin (score=-1.524, requis 5, autolearn=not spam, BAYES_01 -1.52) X-MailScanner-From: monnier@iro.umontreal.ca X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.4 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Xref: main.gmane.org gmane.emacs.devel:23731 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:23731 >> Please try finding out *precisely* which stack slot >> mark_memory is currently examining. Which stack frame is it in? >> What variable is it? >> > Found another case where a stack pointer points to bogus data, > this time in Flet, variable *temps: What do you mean by "found"? Did you inspect the code looking for suspicious things, or did GDB lead you there? > Here we call Feval, which -- at some point in time will trigger GC -- > and "temps" is filled with random data, some of which are bogus Lisp > object pointers. If gcpros are used, it seems safe: the gcpro2.nvars is initially set to 0 so none of the random values in the uninitialized `temps' array are considered and then as the array gets filled gcpro2.nvars is incremented accordingly. Looks fine. If gcpros are not used (i.e. we use conservative stack scanning), it shouldn't be a problem either because the conservative scan goes through some trouble to ensure that it ignores words pointing to non-GC-managed (or non-live) objects. So I think w need to look further. Stefan