bug#61940: 29.0.60; Occasional crash when moving point continously with visual line numbers

[Eli Zaretskii <eliz@gnu.org>]

> From: Simon Pugnet <simon@polaris64.net>
> Cc: 61940@debbugs.gnu.org
> Date: Fri, 03 Mar 2023 16:38:00 +0000
> 
> > I'm not sure I understand what you mean by "attaching to a running
> > instance of Emacs which crashed".  If Emacs crashed, then it no 
> > longer
> > is running, so what exactly happens when Emacs "crashes", and how do
> > you attach GDB to such a "crashed" session?
> 
> I used `gdb --pid=PID' to attach to the process which had crashed (or 
> was at least not redrawing or accepting any user input).

This seems to indicate that Emacs didn't crash, but stop responding
for some reason.  In which case the backtrace you show doesn't tell
anything interesting, it just tells us that Emacs is waiting for
input.

> From there I obtained the backtrace and was able to step, which is
> how I noticed that it seemed to be in a loop. I might have diagnosed
> this incorrectly however.

The file etc/DEBUG in the Emacs repository has instructions for how to
identify the code in which Emacs is looping, if it's looping.  Look
for "If the symptom of the bug is that Emacs fails to respond".