Bug 221281 - app-editors/emacs-{18.59-r4,21.4-r15}: temacs segfaults in dump-emacs w/ kernel 2.6.25
Bug#: 221281 Product:  Gentoo Linux Version: 2007.0 Platform: x86
OS/Version: Linux Status: RESOLVED Severity: major Priority: P2
Resolution: FIXED Assigned To: emacs@gentoo.org Reported By: ulm@gentoo.org
Component: Applications
URL:  http://lkml.org/lkml/2007/10/23/435
Summary: app-editors/emacs-{18.59-r4,21.4-r15}: temacs segfaults in dump-emacs w/ kernel 2.6.25
Keywords:  
Status Whiteboard: 
Opened: 2008-05-10 23:00 0000
Description:   Opened: 2008-05-10 23:00 0000 
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 From Ulrich Müller 2008-05-10 23:02:35 0000 ------- 
Created an attachment (id=152785) [details]
Stack trace

------- Comment #2 From Ulrich Müller 2008-05-10 23:04:03 0000 ------- 
Created an attachment (id=152787) [details]
Kernel config

------- Comment #3 From Ulrich Müller 2008-05-10 23:05:01 0000 ------- 
Created an attachment (id=152789) [details]
emerge --info

------- Comment #4 From Ulrich Müller 2008-05-10 23:18:45 0000 ------- 
Created an attachment (id=152791) [details]
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 From Ulrich Müller 2008-05-11 00:36:17 0000 ------- 
Created an attachment (id=152799) [details]
Patch for 18.59: 05_all_bss-heap-gap.patch

------- Comment #6 From Ulrich Müller 2008-05-11 01:23:05 0000 ------- 
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 From Ulrich Müller 2008-05-11 21:52:02 0000 ------- 
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 From Ulrich Müller 2008-05-13 06:18:46 0000 ------- 
Stabilisation of emacs-21.4-r17 is handled in bug 221197.

------- Comment #9 From Ulrich Müller 2008-05-29 16:50:21 0000 ------- 
@x86: Please stabilise emacs-18.59-r5.
Preferably it should be tested with kernel 2.6.25.

------- Comment #10 From Christian Faulhammer 2008-05-31 13:40:12 0000 ------- 
x86 stable, closing