Re: 64-bit emacs crashes a lot

[Eli Zaretskii]

> Date: Fri, 16 Aug 2013 07:41:44 -0400
> From: Ryan Johnson <address@hidden>
> 
> On 16/08/2013 4:58 AM, Eli Zaretskii wrote:
> > Again, please move this discussion to emacs-devel.
> Back pointer: http://cygwin.com/ml/cygwin/2013-08/msg00273.html
> 
> >> Date: Thu, 15 Aug 2013 22:35:54 -0400
> >> From: Ken Brown <address@hidden>
> >>
> >> 1. Invoke 'emacs-nox -Q' in mintty.
> >>
> >> 2. M-x compile C-a C-k ls RET
> >>
> >> 3. C-x o
> >>
> >> 4. Hit 'g' repeatedly.
> >>
> >> I got it to abort with Fatal error 6 after slightly over 100 repetitions.
> >>
> >> I then tried the same thing with emacs-X11 (running under X, not in
> >> mintty).  I hit 'g' 200 times without a problem.  I repeated this with
> >> emacs-w32, again 200 times without a problem.
> >>
> >> So there's a bug somewhere.  But if it's an emacs bug, it's strange that
> >> it only occurs with emacs-nox and not with either of the GUI versions of
> >> emacs.
> > I suspect that buffer relocation might be the reason.  Can you show a
> > backtrace from the fatal error in an unoptimized build, with the above
> > recipe?
> I'll try to get one. Meanwhile, is there a quick way to disable buffer 
> relocation as a sanity test?

I don't think so, but maybe it's already disabled in your build.  What
do you see on these two lines when configure finishes:

  Should Emacs use a relocating allocator for buffers?    yes
  Should Emacs use mmap(2) for buffer allocation?         no

In any case, you could configure with --enable-checking=all, it might
catch the problem earlier.

> If the optimized build still crashes reliably without it, the real
> problem is probably something else.

Maybe, but not necessarily.