From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.bugs Subject: bug#29066: 26.0.90; crash in gc involving buffer local symbols Date: Tue, 31 Oct 2017 23:00:10 +0100 Message-ID: <87y3nrvuz9.fsf@linux-m68k.org> References: <83a808tlqp.fsf@gnu.org> <838tfst27n.fsf@gnu.org> <87efpjzv2p.fsf@linux-m68k.org> <834lqfta80.fsf@gnu.org> <877evbxe1e.fsf@linux-m68k.org> <83r2tjrr92.fsf@gnu.org> <87375zxc69.fsf@linux-m68k.org> <83lgjrrpn9.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1509487284 28671 195.159.176.226 (31 Oct 2017 22:01:24 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 31 Oct 2017 22:01:24 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) Cc: 29066@debbugs.gnu.org, vgatien-baron@janestreet.com, mshinwell@janestreet.com To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Oct 31 23:01:19 2017 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e9eas-0006Fz-Lz for geb-bug-gnu-emacs@m.gmane.org; Tue, 31 Oct 2017 23:01:10 +0100 Original-Received: from localhost ([::1]:47509 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e9eaz-0007kl-Ph for geb-bug-gnu-emacs@m.gmane.org; Tue, 31 Oct 2017 18:01:17 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:46019) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e9eao-0007il-OE for bug-gnu-emacs@gnu.org; Tue, 31 Oct 2017 18:01:10 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e9eal-0002Jx-LY for bug-gnu-emacs@gnu.org; Tue, 31 Oct 2017 18:01:06 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:36019) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1e9eal-0002Jl-Hh for bug-gnu-emacs@gnu.org; Tue, 31 Oct 2017 18:01:03 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1e9eal-0008TZ-9q for bug-gnu-emacs@gnu.org; Tue, 31 Oct 2017 18:01:03 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Andreas Schwab Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 31 Oct 2017 22:01:03 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 29066 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 29066-submit@debbugs.gnu.org id=B29066.150948721632507 (code B ref 29066); Tue, 31 Oct 2017 22:01:03 +0000 Original-Received: (at 29066) by debbugs.gnu.org; 31 Oct 2017 22:00:16 +0000 Original-Received: from localhost ([127.0.0.1]:44698 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e9eZz-0008SF-W9 for submit@debbugs.gnu.org; Tue, 31 Oct 2017 18:00:16 -0400 Original-Received: from mail-out.m-online.net ([212.18.0.9]:46034) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e9eZy-0008S4-7d for 29066@debbugs.gnu.org; Tue, 31 Oct 2017 18:00:14 -0400 Original-Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 3yRQJD4MvSz1qs0q; Tue, 31 Oct 2017 23:00:12 +0100 (CET) Original-Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 3yRQJD3NRtz1tSmb; Tue, 31 Oct 2017 23:00:12 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Original-Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id cC3-u9XkBZ4C; Tue, 31 Oct 2017 23:00:10 +0100 (CET) X-Auth-Info: NnFA77Ch1pQ7POocJrgq8JIsnIW/1LMZp1GJpqYxZmht3OPXcq7Fvx6Ng7FlsriH Original-Received: from localhost (ppp-188-174-147-245.dynamic.mnet-online.de [188.174.147.245]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Tue, 31 Oct 2017 23:00:10 +0100 (CET) Original-Received: by localhost (Postfix, from userid 1000) id 155D52C224F; Tue, 31 Oct 2017 23:00:10 +0100 (CET) X-Yow: Th' PINK SOCK... soaking... soaking... soaking... Th' PINK SOCK... washing... washing... washing... Th' PINK SOCK... rinsing... rinsing... rinsing... In-Reply-To: <83lgjrrpn9.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 31 Oct 2017 23:08:58 +0200") 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: 208.118.235.43 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.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:139294 Archived-At: On Okt 31 2017, Eli Zaretskii wrote: >> From: Andreas Schwab >> Cc: vgatien-baron@janestreet.com, 29066@debbugs.gnu.org, mshinwell@janestreet.com >> Date: Tue, 31 Oct 2017 22:03:26 +0100 >> >> >> A symbol on the symbol_free_list is a freed symbol, not available for >> >> use. >> > >> > I guess you are saying that sweep_symbols has a bug? Because it hits >> > this "freed" symbol every GC, AFAICT. >> >> Since GC is special, it needs to do special things. > > But the crash due to double-free did happen as part of GC doing those > "special things". That's why it helps to clear the pointer to the freed memory, instead of leaving it dangling. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."