bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects

[Andrea Corallo]

Eli Zaretskii <eliz@gnu.org> writes:

> FETCH_END calls marker-position, and that segfaults because the marker
> points to invalid memory, which was probably unmapped from the process
> address space (so I guess this is w32-specific, as GNU systems don't
> really return memory to the system).  The start_marker is also
> invalid, it's just that FETCH_END is called first.
>
> Since the previous call to before-change-functions already used the
> same overlay markers, I suspect that the call to
> before-change-functions caused the memory to be unmapped (perhaps due
> to GC).  As you see below, the value of before-change-functions is
>
>   (t syntax-ppss-flush-cache)
>
> So the prime suspect is what happens when syntax-ppss-flush-cache
> runs, and thus I CC Stefan.  The main question to answer now from my
> POV is how come a marker on buffer position 3116 which was valid
> before before-change-functions was called became invalid as result of
> some Lisp, in particular as result of calling before-change-functions.
>
> Here's the backtrace; ideas for further debugging are welcome.

Hi Eli,

I'be curious of the outcome if you had a look to your 'garbage_collect'
assembly to investigate the possible relation with 41357 as suggested
here
https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-05/msg01095.html

Hope it helps

  Andrea

-- 
akrl@sdf.org