GNU bug report logs - #34206
Pdumper giving a segfault

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Compro Prasad <comproprasad <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 12:03:59 +0530

Emacs source: official master branch (commit: 7960951d5d)
Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
(commit: f5eef2127ad4d)
Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
(commit: 8a1eebc65f9a)

Build command: ./configure --enable-checking='yes,glyphs'
--enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
make -j2

GDB log: https://pastebin.com/2uMPHCRV

OS: Antergos(Arch Linux)
Compiler: gcc version 8.2.1 20181127 (GCC)

Can't provide further information because Emacs segfaults before it
can load any elisp packages while loading the dump file.

I might be doing something wrong here. Can you please guide me how to
use the pdumper in Emacs or what info topic is it under?

Regards,
Abhishek(Compro) Prasad

Message #8 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Compro Prasad <comproprasad <at> gmail.com>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 10:06:26 +0200

> From: Compro Prasad <comproprasad <at> gmail.com>
> Date: Sat, 26 Jan 2019 12:03:59 +0530
> 
> Emacs source: official master branch (commit: 7960951d5d)
> Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
> (commit: f5eef2127ad4d)
> Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
> (commit: 8a1eebc65f9a)
> 
> Build command: ./configure --enable-checking='yes,glyphs'
> --enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
> make -j2
> 
> GDB log: https://pastebin.com/2uMPHCRV

This seems to indicate your configuration is quite complex, and I
cannot easily understand what are you doing that is different from
the normal build and "emacs -Q" to start Emacs.  In particular, this:

  $ gdb ./src/emacs-27.0.50.11
  Reading symbols from ./src/emacs-27.0.50.11...done.
  (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
  Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"

indicates that your pdump file is spacemacs.pdmp, but I don't know how
that file was produced, and I cannot easily understand what is
different in your build procedure from the normal upstream build of
Emacs.

Maybe you should first take this up with then maintainers of the
Compro-Prasad/spacemacs package.

> OS: Antergos(Arch Linux)
> Compiler: gcc version 8.2.1 20181127 (GCC)
> 
> Can't provide further information because Emacs segfaults before it
> can load any elisp packages while loading the dump file.

The backtrace indicates that it segfaults _after_ loading the dump
file, inside the call to init_buffer.

> I might be doing something wrong here. Can you please guide me how to
> use the pdumper in Emacs or what info topic is it under?

There's no difference in how pdump'ed Emacs should be used, it's the
same as you'd use an unexec'ed Emacs.

I suggest to file an issue with the maintainers of
Compro-Prasad/spacemacs.

Message #11 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: comproprasad <at> gmail.com
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 10:22:16 +0200

> Date: Sat, 26 Jan 2019 10:06:26 +0200
> From: Eli Zaretskii <eliz <at> gnu.org>
> Cc: 34206 <at> debbugs.gnu.org
> 
> I suggest to file an issue with the maintainers of
> Compro-Prasad/spacemacs.

Or maybe report this to the maintainers of syl20bnr/spacemacs from
where you forked yours.

Message #14 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Compro Prasad <comproprasad <at> gmail.com>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 12:49:24 +0200

> From: Compro Prasad <comproprasad <at> gmail.com>
> Date: Sat, 26 Jan 2019 14:33:57 +0530
> Cc: 34206 <at> debbugs.gnu.org
> 
> > > GDB log: https://pastebin.com/2uMPHCRV
> >
> > This seems to indicate your configuration is quite complex, and I
> > cannot easily understand what are you doing that is different from
> > the normal build and "emacs -Q" to start Emacs.  In particular, this:
> >
> >   $ gdb ./src/emacs-27.0.50.11
> >   Reading symbols from ./src/emacs-27.0.50.11...done.
> >   (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
> >   Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
> >
> > indicates that your pdump file is spacemacs.pdmp, but I don't know how
> > that file was produced, and I cannot easily understand what is
> > different in your build procedure from the normal upstream build of
> > Emacs.
> I don't know if you can help me but I have some more information on
> how the dump might be produced.
> 
> https://github.com/Compro-Prasad/spacemacs/blob/pdumper-is-in-master/core/core-dumper.el#L68

I don't think this helps much, as I don't really know anything about
spacemacs and its build procedures.

> I went a bit further and tried executing the following using `C-x C-e`
> while running spacemacs:
> 
>    (dump-emacs-portable "~/test.pdmp")
> 
> It gave me: eval: unsupported object type in dump: window configuration
> 
> Is this a bug or I am supposed to run Emacs in batch mode while dumping?

Yes, dump-emacs-portable can only be invoked in batch mode.

Message #17 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Compro Prasad <comproprasad <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 14:33:57 +0530

On Sat, Jan 26, 2019 at 1:36 PM Eli Zaretskii <eliz <at> gnu.org> wrote:
>
> > From: Compro Prasad <comproprasad <at> gmail.com>
> > Date: Sat, 26 Jan 2019 12:03:59 +0530
> >
> > Emacs source: official master branch (commit: 7960951d5d)
> > Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
> > (commit: f5eef2127ad4d)
> > Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
> > (commit: 8a1eebc65f9a)
> >
> > Build command: ./configure --enable-checking='yes,glyphs'
> > --enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
> > make -j2
> >
> > GDB log: https://pastebin.com/2uMPHCRV
>
> This seems to indicate your configuration is quite complex, and I
> cannot easily understand what are you doing that is different from
> the normal build and "emacs -Q" to start Emacs.  In particular, this:
>
>   $ gdb ./src/emacs-27.0.50.11
>   Reading symbols from ./src/emacs-27.0.50.11...done.
>   (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
>   Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
>
> indicates that your pdump file is spacemacs.pdmp, but I don't know how
> that file was produced, and I cannot easily understand what is
> different in your build procedure from the normal upstream build of
> Emacs.
I don't know if you can help me but I have some more information on
how the dump might be produced.

https://github.com/Compro-Prasad/spacemacs/blob/pdumper-is-in-master/core/core-dumper.el#L68

I went a bit further and tried executing the following using `C-x C-e`
while running spacemacs:

   (dump-emacs-portable "~/test.pdmp")

It gave me: eval: unsupported object type in dump: window configuration

Is this a bug or I am supposed to run Emacs in batch mode while dumping?

Message #20 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Compro Prasad <comproprasad <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 20:35:41 +0530

On Sat, Jan 26, 2019 at 4:19 PM Eli Zaretskii <eliz <at> gnu.org> wrote:
>
> > From: Compro Prasad <comproprasad <at> gmail.com>
> > Date: Sat, 26 Jan 2019 14:33:57 +0530
> > Cc: 34206 <at> debbugs.gnu.org
> >
> > > > GDB log: https://pastebin.com/2uMPHCRV
> > >
> > > This seems to indicate your configuration is quite complex, and I
> > > cannot easily understand what are you doing that is different from
> > > the normal build and "emacs -Q" to start Emacs.  In particular, this:
> > >
> > >   $ gdb ./src/emacs-27.0.50.11
> > >   Reading symbols from ./src/emacs-27.0.50.11...done.
> > >   (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
> > >   Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
> > >
> > > indicates that your pdump file is spacemacs.pdmp, but I don't know how
> > > that file was produced, and I cannot easily understand what is
> > > different in your build procedure from the normal upstream build of
> > > Emacs.
> > I don't know if you can help me but I have some more information on
> > how the dump might be produced.
> >
> > https://github.com/Compro-Prasad/spacemacs/blob/pdumper-is-in-master/core/core-dumper.el#L68
>
> I don't think this helps much, as I don't really know anything about
> spacemacs and its build procedures.
Spacemacs is just another Emacs configuration. It doesn't mess with
the official Emacs source. This doesn't require any additional build
steps.
> > I went a bit further and tried executing the following using `C-x C-e`
> > while running spacemacs:
> >
> >    (dump-emacs-portable "~/test.pdmp")
> >
> > It gave me: eval: unsupported object type in dump: window configuration
> >
> > Is this a bug or I am supposed to run Emacs in batch mode while dumping?
>
> Yes, dump-emacs-portable can only be invoked in batch mode.
Thanks for the information.

Can you please give a simple example of the best way to dump Emacs and
reload the dump file? I would also appreciate any links to the Emacs
info manual.

Message #23 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Compro Prasad <comproprasad <at> gmail.com>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 17:18:38 +0200

> From: Compro Prasad <comproprasad <at> gmail.com>
> Date: Sat, 26 Jan 2019 20:35:41 +0530
> Cc: 34206 <at> debbugs.gnu.org
> 
> > > https://github.com/Compro-Prasad/spacemacs/blob/pdumper-is-in-master/core/core-dumper.el#L68
> >
> > I don't think this helps much, as I don't really know anything about
> > spacemacs and its build procedures.
> Spacemacs is just another Emacs configuration. It doesn't mess with
> the official Emacs source. This doesn't require any additional build
> steps.

But AFAITCT, it dumps Emacs from a separate file, not from loadup.el,
right?  And that separate file does something before dumping in
addition to what loadup.el does, right?  These extras is what confuses
me.  Granted, when I build Emacs from the master branch, it doesn't
segfault on startup.

> > Yes, dump-emacs-portable can only be invoked in batch mode.
> Thanks for the information.
> 
> Can you please give a simple example of the best way to dump Emacs and
> reload the dump file?

The only way I know of is to clone the Emacs Git's master branch and
build it as described in INSTALL.REPO.

> I would also appreciate any links to the Emacs info manual.

The portable dumping is described in the ELisp manual in the master
branch, see the node "Building Emacs" there.  There's also some
information in the Emacs manual, where the command-line options are
described, and in NEWS.

Message #26 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Daniel Colascione <dancol <at> dancol.org>
To: Eli Zaretskii <eliz <at> gnu.org>, Compro Prasad <comproprasad <at> gmail.com>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 19:50:17 -0800

On 1/26/19 2:49 AM, Eli Zaretskii wrote:
>> From: Compro Prasad <comproprasad <at> gmail.com>
>> Date: Sat, 26 Jan 2019 14:33:57 +0530
>> Cc: 34206 <at> debbugs.gnu.org
>>
>>>> GDB log: https://pastebin.com/2uMPHCRV
>>>
>>> This seems to indicate your configuration is quite complex, and I
>>> cannot easily understand what are you doing that is different from
>>> the normal build and "emacs -Q" to start Emacs.  In particular, this:
>>>
>>>    $ gdb ./src/emacs-27.0.50.11
>>>    Reading symbols from ./src/emacs-27.0.50.11...done.
>>>    (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
>>>    Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
>>>
>>> indicates that your pdump file is spacemacs.pdmp, but I don't know how
>>> that file was produced, and I cannot easily understand what is
>>> different in your build procedure from the normal upstream build of
>>> Emacs.
>> I don't know if you can help me but I have some more information on
>> how the dump might be produced.
>>
>> https://github.com/Compro-Prasad/spacemacs/blob/pdumper-is-in-master/core/core-dumper.el#L68
> 
> I don't think this helps much, as I don't really know anything about
> spacemacs and its build procedures.
> 
>> I went a bit further and tried executing the following using `C-x C-e`
>> while running spacemacs:
>>
>>     (dump-emacs-portable "~/test.pdmp")
>>
>> It gave me: eval: unsupported object type in dump: window configuration
>>
>> Is this a bug or I am supposed to run Emacs in batch mode while dumping?
> 
> Yes, dump-emacs-portable can only be invoked in batch mode.

That's not quite true. There's no particular reason it can't be invoked 
in any mode, but as the message indicates, there are some objects that 
pdumper doesn't know how to dump. Packages maintaining these objects 
should add-function to dump-emacs-portable to temporarily make these 
objects disappear while a dump is in progress.

In any case, neither the dump nor load should actually segfault. A 
segfault is a bug.

Message #29 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Daniel Colascione <dancol <at> dancol.org>
To: Compro Prasad <comproprasad <at> gmail.com>, 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Sat, 26 Jan 2019 19:52:26 -0800

On 1/25/19 10:33 PM, Compro Prasad wrote:
> Emacs source: official master branch (commit: 7960951d5d)
> Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
> (commit: f5eef2127ad4d)
> Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
> (commit: 8a1eebc65f9a)
> 
> Build command: ./configure --enable-checking='yes,glyphs'
> --enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
> make -j2
> 
> GDB log: https://pastebin.com/2uMPHCRV
> 
> OS: Antergos(Arch Linux)
> Compiler: gcc version 8.2.1 20181127 (GCC)
> 
> Can't provide further information because Emacs segfaults before it
> can load any elisp packages while loading the dump file.
> 
> I might be doing something wrong here. Can you please guide me how to
> use the pdumper in Emacs or what info topic is it under?

That looks like a legitimate bug. I don't know anything about spacemacs. 
Can you provide a recipe for reproducing this crash starting from a 
stock master checkout? Thanks.

Message #32 received at 34206 <at> debbugs.gnu.org (full text, mbox):

From: Compro Prasad <comproprasad <at> gmail.com>
To: Daniel Colascione <dancol <at> dancol.org>
Cc: 34206 <at> debbugs.gnu.org
Subject: Re: bug#34206: Pdumper giving a segfault
Date: Mon, 28 Jan 2019 17:49:39 +0530

On Sun, Jan 27, 2019 at 9:22 AM Daniel Colascione <dancol <at> dancol.org> wrote:
>
> On 1/25/19 10:33 PM, Compro Prasad wrote:
> > Emacs source: official master branch (commit: 7960951d5d)
> > Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
> > (commit: f5eef2127ad4d)
> > Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
> > (commit: 8a1eebc65f9a)
> >
> > Build command: ./configure --enable-checking='yes,glyphs'
> > --enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
> > make -j2
> >
> > GDB log: https://pastebin.com/2uMPHCRV
> >
> > OS: Antergos(Arch Linux)
> > Compiler: gcc version 8.2.1 20181127 (GCC)
> >
> > Can't provide further information because Emacs segfaults before it
> > can load any elisp packages while loading the dump file.
> >
> > I might be doing something wrong here. Can you please guide me how to
> > use the pdumper in Emacs or what info topic is it under?
>
> That looks like a legitimate bug. I don't know anything about spacemacs.
> Can you provide a recipe for reproducing this crash starting from a
> stock master checkout? Thanks.

I fixed it by setting dotspacemacs-editing-style to 'vim from 'hybrid
. You can see it here:
https://github.com/Compro-Prasad/.spacemacs.d/commit/70033fb6c429244d0a72663e8258fe05637f5cfd#diff-64ed6d0a7a4f2eaf33cacc2454a19cffL234

You can clone the repo in the above link to `~/.spacemacs.d` and clone
https://github.com/Compro-Prasad/spacemacs (branch:
pdumper-is-in-master) to `~/.emacs.d`. Then start Emacs(Packages will
be downloaded for the first time). It should work perfectly fine. You
can see the dumping status in `*spacemacs-dumper*` buffer. Then
specify the command:

emacs-27.0.50 --dump-file ~/.emacs.d/.cache/dumps/spacemacs.pdmp

to load the dump. This won't work(will crash) if the
dotspacemacs-editing-style is 'hybrid in `~/.spacemacs.d/init.el`

The emacs 27 executable used was by building from the official master branch.

If you are doubtful about any of the above steps then you can ask me
or ask spacemacs specific questions at
https://gitter.im/syl20bnr/spacemacs .

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