Subject: Re: bug#54183: 28.0.91; Emacs crashes on bookmark-jump

From: Eli Zaretskii <[email-masked]>
Date: Mon, 28 Feb 2022 16:54:35 +0200

> From: Gustavo Barros <[email-masked]>
> Cc: [email-masked]
> Date: Mon, 28 Feb 2022 11:30:51 -0300
> 
> So I started two Emacs instances, one `./emacsclient -c -a=""' from 
> `lib-src/', and another standalone instance.

That's the right way.

> So I starded GDB from the 
> standalone instance using the PID from the daemon with `M-x gdb RET gdb 
> -i=mi -p <emacs daemon pid> RET'.  This gets me almost there I think, 
> but not quite.  It appears to attach successfully:
> 
> #+begin_example
> Attaching to process 10785
> [New LWP 10786]
> [New LWP 10787]
> [New LWP 10788]
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library 
> "/lib/x86_64-linux-gnu/libthread_db.so.1".
> 0x00007fa139664246 in __pselect (nfds=21, readfds=0x7fff480be100, 
> writefds=0x7fff480be180, exceptfds=0x0, timeout=<optimized out>, 
> sigmask=<optimized out>) at ../sysdeps/unix/sysv/linux/pselect.c:48
> 48	../sysdeps/unix/sysv/linux/pselect.c: No such file or directory.
> #+end_example
> 
> However, I also get a message that "Target doesn’t support non-stop 
> mode.  Turning it off."  And indeed, the other instance to which I 
> attached GDB becomes completely unresponsive until I quit GDB, so I 
> cannot trigger the problem, since I cannot interact with it.

After you attach GDB, and see the GBD's prompt "(gdb)", type
"continue" into the buffer where Emacs shows this prompt.  Then the
Emacs process to which you attached GDB will resume running, and you
can proceed reproducing the problem in that Emacs.

If and when you succeed to reproduce the crash, you will see GDB take
control and say that the Emacs being debugged encountered a fatal
signal.  It will then show the prompt "(gdb)" again.  Type there the
following command:

   thread apply all bt

Then post here everything that command produces.