On 2010-12-02 10:01 +0000, YAMAMOTO Mitsuharu wrote:
>> BTW, `mac-mouse-wheel-smooth-scroll' does not work reliably. It can
>> freeze emacs (Can't be interrupted by C-g). So I am not using it for
>> now.
>
> I've never experienced this.  If it does not happen with -Q, then your
> configuration has something to do with this problem.
>
> Also, because the actual scrolling code is mostly implemented at the
> Lisp level (without touching inhibit-quit), your problem may indicate
> that there is some infinite loop or hang possibly in the
> platform-independent part such as redisplay.  Identifying the place of
> infinite loop or hang using a debugger may help (see the "If the
> symptom of the bug is that Emacs fails to respond" section in
> etc/DEBUG).

Indeed there is an infinite loop. But I wasn't able to reproduce the
problem with a vanilla Emacs. The problem happens when I am scrolling up
(my hand move from bottom to top on the trackpad) and the infinite loop
happens in xdisp.c between line 12630 and 12789 (the gdb log is
attached).

I also find a way to reproduce this problem easily with Emacs -q:

1. eval

  (setq scroll-conservatively 100)
  (setq scroll-preserve-screen-position 'always)

2. try scrolling in a buffer