From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Noam Postavsky Newsgroups: gmane.emacs.bugs Subject: bug#30931: 27.0.50; Crash in "Automatic GC" Date: Fri, 30 Mar 2018 01:39:30 -0400 Message-ID: <87zi2qp1f1.fsf@gmail.com> References: <0eb14aa5-8110-8336-5d3d-fac46ccc23f3@zoho.com> <83h8p4hok0.fsf@gnu.org> <48726674-57ed-a3bc-b4dc-e36747d30f90@zoho.com> <87605eqwam.fsf@gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1522388292 11095 195.159.176.226 (30 Mar 2018 05:38:12 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 30 Mar 2018 05:38:12 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.90 (gnu/linux) Cc: 30931 <30931@debbugs.gnu.org> To: =?UTF-8?Q?Micha=C5=82?= Kondraciuk Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Fri Mar 30 07:38:07 2018 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 1f1mjn-0002mm-BT for geb-bug-gnu-emacs@m.gmane.org; Fri, 30 Mar 2018 07:38:07 +0200 Original-Received: from localhost ([::1]:33547 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f1mlq-0000Il-N0 for geb-bug-gnu-emacs@m.gmane.org; Fri, 30 Mar 2018 01:40:14 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:36157) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f1mlj-0000Gs-9a for bug-gnu-emacs@gnu.org; Fri, 30 Mar 2018 01:40:08 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f1mlf-0005eF-9V for bug-gnu-emacs@gnu.org; Fri, 30 Mar 2018 01:40:07 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:51388) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1f1mlf-0005eA-3z for bug-gnu-emacs@gnu.org; Fri, 30 Mar 2018 01:40:03 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1f1mld-0005bc-V8 for bug-gnu-emacs@gnu.org; Fri, 30 Mar 2018 01:40:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Noam Postavsky Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 30 Mar 2018 05:40:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 30931 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: confirmed Original-Received: via spool by 30931-submit@debbugs.gnu.org id=B30931.152238838021516 (code B ref 30931); Fri, 30 Mar 2018 05:40:01 +0000 Original-Received: (at 30931) by debbugs.gnu.org; 30 Mar 2018 05:39:40 +0000 Original-Received: from localhost ([127.0.0.1]:59285 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f1mlH-0005ay-JO for submit@debbugs.gnu.org; Fri, 30 Mar 2018 01:39:39 -0400 Original-Received: from mail-io0-f177.google.com ([209.85.223.177]:38045) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f1mlF-0005aj-BW for 30931@debbugs.gnu.org; Fri, 30 Mar 2018 01:39:37 -0400 Original-Received: by mail-io0-f177.google.com with SMTP id b20so10090296iof.5 for <30931@debbugs.gnu.org>; Thu, 29 Mar 2018 22:39:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version:content-transfer-encoding; bh=xnbv/W7xfWo0vXamCjT/mpjCZmSH6AVrXorjshwwR5M=; b=ikY1f9uplLOYZEKgfS8on4TU1pJANOZBD2KvWmvno5D/xf4jlYWHPPEfPbEz3Cbw9l N5LJyjKeDFpf9K1Tyx5SNCHoDMAuPQH+8gkqtuKx7HgPGGqQ1/9w0tl33l7uXORifJ3G zNIdk6bhlb6kHOufMxq9l+NA6z3MPiqZoSm7denFdw6XaODuyTE45q2+FNcbWTNVK++l T/Jt5cUb5zBh7TULR5eFmy+Xf6Di6X+OQhCoikY5h0HENA1nz3lFwfh2Zm0gpfeEhQ5g HMeJPssxLzuTlaGyN2U1o3DzmYvNUYog662VboXHZEhpX+U5iegA5RLrgrGXOK4e9RUr PiUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:references:date:in-reply-to :message-id:user-agent:mime-version:content-transfer-encoding; bh=xnbv/W7xfWo0vXamCjT/mpjCZmSH6AVrXorjshwwR5M=; b=mBwbWSOShq6BDzcI8S2iZLUTa8trbLqA/4jfdwONzeotSI5Zuxw0U3+IB2Qn2vHo58 i9ijm1OPW/11/siC9w1KkSg7beVz7bJK8j+7a5EQbdBPtttLMSl2GWD0dblTFhea719t AtgA8THshkFOh0h2Tio5CPfwm/KiL6i/dtDZr3bztZY2HsS73HchlZhDdvjliFNskHuq fcp1UCtT/TWwrT090a4Gr12sfmjh5nlxRvC9ofVJND81iobcmIts3Hs9SWeYwXSJF4YW /DVRjmjRJLu12FhTN5A4vWqplEMpbobZNdn9z807nEupTffloKnnZDujX3m4v1hC1XVF sNkw== X-Gm-Message-State: AElRT7HD1cESFZpQINcfDYpAggf5dNHF+EqscwaTuneZ8iPdGKHvAZMX bM2oEjz1eT3gM/7qYnZ8l4nwpw== X-Google-Smtp-Source: AG47ELsgYgAmsgKITnvNs/i96quii7kQv2z3D66ZOos1zMsewidj/O2ZnouOcNnb7qnMBZgqjJ9SKg== X-Received: by 10.107.53.146 with SMTP id k18mr59341209ioo.292.1522388371684; Thu, 29 Mar 2018 22:39:31 -0700 (PDT) Original-Received: from zebian (cbl-45-2-119-34.yyz.frontiernetworks.ca. [45.2.119.34]) by smtp.googlemail.com with ESMTPSA id 40sm4915732iol.39.2018.03.29.22.39.30 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 29 Mar 2018 22:39:31 -0700 (PDT) In-Reply-To: <87605eqwam.fsf@gmail.com> (Noam Postavsky's message of "Thu, 29 Mar 2018 19:47:13 -0400") 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:144719 Archived-At: Noam Postavsky writes: > Micha=C5=82 Kondraciuk writes: > >> I don't know if it helps, but I was able to reproduce a crash in the >> same place (mark_object()) with bare Emacs, however only in 27.0.50. > > This is very helpful, thank you. Okay, with this recipe, I was able to put a breakpoint in free_marker and find where the problem is: save_restriction_save creates markers to represent the current restriction, record_marker_adjustments (called from delete-region) puts all buffer markers onto the buffer undo list, and save_restriction_restore frees the markers created in save_restriction_save. save_restriction_save (void) { [...] beg =3D build_marker (current_buffer, BEGV, BEGV_BYTE); end =3D build_marker (current_buffer, ZV, ZV_BYTE); record_marker_adjustments (ptrdiff_t from, ptrdiff_t to) { [...] for (m =3D BUF_MARKERS (current_buffer); m; m =3D m->next) { [...] XSETMISC (marker, m); bset_undo_list (current_buffer, Fcons (Fcons (marker, make_number (adjustment)), BVAR (current_buffer, undo_list))); save_restriction_restore (Lisp_Object data) { [...] /* These aren't needed anymore, so don't wait for GC. */ free_marker (XCAR (data)); free_marker (XCDR (data)); So the following is enough to trigger the bug: (with-temp-buffer (insert "1234567890") (setq buffer-undo-list nil) (narrow-to-region 2 5) (save-restriction (widen) (delete-region 1 6)) (princ (format "%S" buffer-undo-list) #'external-debugging-output) (type-of (car (nth 1 buffer-undo-list)))) Surprisingly, printing works on a Lisp_Misc_Free object, so this prints (("12345" . 1) (# . -1) (# . 1)) before aborting in Ftype_of. Calling garbage-collect instead of type-of also aborts. Calling neither seems to be okay, since in that case the Lisp_Misc_Free objects somehow turn into #. For solving this, I guess the easiest would be to have save_restriction_restore do (set-marker m nil) instead of free_marker. Might make more sense to avoid putting those markers onto the undo list in the first place though.