Seek advice about crashes dealing with fonts/faces

Seek advice about crashes dealing with fonts/faces

[Ludwig, Mark]

Greetings,

I've had Emacs 24.4 crash a couple of times this week, and
wonder if anyone else has seen anything like this or has
advice about how to make an actionable bug report.

Emacs is running on Solaris, with the X display pointing to
eXceed (i.e., Windoze).

Both of the core dumps have the same 8 functions leading up
to a bus error (SIGBUS):

FcPatternObjectFindElt (causes/triggers the SIGBUS)
FcFontSetList
FcFontList
ftfont_list
xftfont_list
font_list_entities
font_find_for_lface
font_load_for_lface
 
Two different functions call font_load_for_lface in my two
core files, and the rest of the calls are quite different.

I can't reproduce this at will, but I have a feeling it will
recur.  Any advice about how to catch it or get better
diagnostic information for a bug report?  I tried searching
debbugs.gnu.org for similar bugs, and don't see any -- but I
might not be searching effectively.  Do I already have
enough for an actionable bug report?  (I don't think I do.)

I built this Emacs, so I can rebuild it if it will help
diagnose this.  I abbreviated the stack trace, but it has
line numbers in the bottom five functions.  The top three
are obviously Lisp....

Thanks in advance,
Mark
--
Mark Ludwig
Lifecycle Coll
Product Lifecycle Management

Siemens Industry Sector
Siemens Product Lifecycle Management Software Inc.
5939 Rice Creek Parkway
Shoreview, MN  55126 United States 
Tel.      :+1 (651) 855-6140
Fax      :+1 (651) 855-6280
ludwig.mark@siemens.com 
www.siemens.com/plm 

Re: Seek advice about crashes dealing with fonts/faces

[Eli Zaretskii]

> From: "Ludwig, Mark" <ludwig.mark@siemens.com>
> Date: Wed, 8 Apr 2015 22:19:40 +0000
> 
> I've had Emacs 24.4 crash a couple of times this week, and
> wonder if anyone else has seen anything like this or has
> advice about how to make an actionable bug report.
> 
> Emacs is running on Solaris, with the X display pointing to
> eXceed (i.e., Windoze).
> 
> Both of the core dumps have the same 8 functions leading up
> to a bus error (SIGBUS):
> 
> FcPatternObjectFindElt (causes/triggers the SIGBUS)
> FcFontSetList
> FcFontList
> ftfont_list
> xftfont_list
> font_list_entities
> font_find_for_lface
> font_load_for_lface
>  
> Two different functions call font_load_for_lface in my two
> core files, and the rest of the calls are quite different.
> 
> I can't reproduce this at will, but I have a feeling it will
> recur.  Any advice about how to catch it or get better
> diagnostic information for a bug report?

Run Emacs under GDB, and when it crashes, show the full backtrace.
Also, try to figure out which variable is triggering SIGBUS, and show
that as well.

It is best to build Emacs without optimizations and with -g3
command-line switch to the compiler (or its equivalent, if you don't
use GCC), since the backtrace and the other debug info is much more
reliable then.

> Do I already have enough for an actionable bug report?

You do, but adding the information mentioned above would make the
report much more useful.

SIGBUS actually sounds like a fontconfig bug, so if there's a newer
version of that library, perhaps try using it.  Or maybe look for
similar problems in fontconfig bug database, if there is such a thing.

Re: Seek advice about crashes dealing with fonts/faces

[Stefan Monnier]

> I've had Emacs 24.4 crash a couple of times this week, and
> wonder if anyone else has seen anything like this or has
> advice about how to make an actionable bug report.

Try M-x report-emacs-bug


        Stefan