Bug 221281 – app-editors/emacs-{18.59-r4,21.4-r15}: temacs segfaults in dump-emacs w/ kernel 2.6.25

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Ulrich Müller 2008-05-10 23:00:31 UTC]

Building of app-editors/emacs-21.4-r15 (also 18.59-r4) fails with a segmentation fault in dump-emacs / unexec. This is with the system running gentoo-sources-2.6.25-r2. The problem does not show up with 2.6.24-r7.


LC_ALL=C ./temacs -batch -l loadup dump
[...]
Finding pointers to doc strings...
Finding pointers to doc strings...done
Wrote /var/tmp/portage/app-editors/emacs-21.4-r15/work/emacs-21.4/lib-src/fns-21.4.1.el
Dumping under names emacs and emacs-21.4.1
make[1]: *** [emacs] Segmentation fault
make[1]: *** Deleting file `emacs'
make[1]: Leaving directory `/var/tmp/portage/app-editors/emacs-21.4-r15/work/emacs-21.4/src'
make: *** [src] Error 2

[Comment 1 Ulrich Müller 2008-05-10 23:02:35 UTC]

Created attachment 152785 [details]
Stack trace

[Comment 2 Ulrich Müller 2008-05-10 23:04:03 UTC]

Created attachment 152787 [details]
Kernel config

[Comment 3 Ulrich Müller 2008-05-10 23:05:01 UTC]

Created attachment 152789 [details]
emerge --info

[Comment 4 Ulrich Müller 2008-05-10 23:18:45 UTC]

Created attachment 152791 [details, diff]
Patch for 21.4: 17_all_bss-heap-gap.patch

Patch for Emacs 21.4, backported from Emacs 22.

(A patch for Emacs 18.59 will follow later.)

[Comment 5 Ulrich Müller 2008-05-11 00:36:17 UTC]

Created attachment 152799 [details, diff]
Patch for 18.59: 05_all_bss-heap-gap.patch

[Comment 6 Ulrich Müller 2008-05-11 01:23:05 UTC]

The breakage is caused by the "randomize brk()" patch.
See the LKML, <http://lkml.org/lkml/2007/10/23/435>:

| This is known to break older versions of some emacs variants, whose
| dumper code assumed that the last variable declared in the program is
| equal to the start of the dynamically allocated memory region.

The corresponding kernel parameter is accessible via /proc/sys/kernel/randomize_va_space, the breakage occurs if its value is 2.

[Comment 7 Ulrich Müller 2008-05-11 21:52:02 UTC]

Fixed in emacs-18.59-r5 and emacs-21.4-r16. Leave this bug open until the fixed versions are marked stable (wrt tracker bug 218127).

[Comment 8 Ulrich Müller 2008-05-13 06:18:46 UTC]

Stabilisation of emacs-21.4-r17 is handled in bug 221197.

[Comment 9 Ulrich Müller 2008-05-29 16:50:21 UTC]

@x86: Please stabilise emacs-18.59-r5.
Preferably it should be tested with kernel 2.6.25.

[Comment 10 Christian Faulhammer (RETIRED) 2008-05-31 13:40:12 UTC]

x86 stable, closing