Subject: bug#40734: 26.3; emacs becomes unresponsive after quitting ediff

From: Lars Ingebrigtsen <[email-masked]>
Date: Thu, 22 Oct 2020 17:09:26 +0200

Christian Brechbühler <[email-masked]> writes:

>    Started Emacs from Ubuntu Applications, the icon with the white
>    calligraphic "E" in a purple circle.
>    I had two buffers open ("Alerts" and "config" from smokeping).
>    M-x ediff-buffers
>    n n n  (to advance to difference #3)
>    b      (copy content of buffer B into A)
>    q y    (quit ediff, confirm)
>
> After this, emacs is unresponsive.  This behavior is similar to
> bug#20175 and bug#21796, which are years old and
> merged/archived/wontfix.  The difference is that they only lost keyboard
> focus; for me mouse input doesn't work either.

Do you have a recipe to reproduce this bug starting from "emacs -Q"?

> To me it looks like thread 1 was handling a segmentation fault.  This is
> different from the older bugs.

Yes, it does look somewhat like a segfault, that is then (possibly)
being blocked by some other thread...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no