GNU bug report logs - #47244
28.0.50; SIGSEGV in long-runnning Emacs

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Message #329 received at 47244 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Michael Welsh Duggan <mwd <at> md5i.com>, Michael Welsh Duggan <mwd <at> cert.org>
Cc: "47244 <at> debbugs.gnu.org" <47244 <at> debbugs.gnu.org>,
 "schwab <at> linux-m68k.org" <schwab <at> linux-m68k.org>
Subject: Re: bug#47244: 28.0.50; SIGSEGV in long-runnning Emacs
Date: Wed, 7 Apr 2021 11:00:36 +0200

[Message part 1 (text/plain, inline)]

> Just a shot in the dark here.  The only way I can think of this
> occurring (Vwindow_list being too small), is that something modified
> Vwindow_list when we don't expect it to be modified.  I looked through
> all the uses of Vwindow_list and window_list(), and they all look
> kosher.  The only modification seems to be setting Vwindow_list to nil.
> But window_list() does call into lisp (nconc2, which calls Fnconc) when
> constructing Vwindow_list, and it uses Vwindow_list as a temporary in
> the process.  Is it possible that during that call something happens
> asynchronously (via gc?) that calls something that sets Vwindow_list
> to nil again, while Vwindow_list is being constructed?

Improbable but I attached some code that could detect such an
incidence.  Put a breakpoint at the

	Vwindow_list = window_list_2;

line.

> I don't think
> so, off hand, but I'm grasping at straws.

I also added a variable called `window-list-lengths' which records the
last 20 or so last changes in the number of windows seen by window_list.
Maybe you can detect some strange 2 ~> 6 or 6 ~> 2 change while running
Gnus.  I'm still not sure whether your daemon setup could be involved
somehow.

martin

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