bug#58923: Malformed core dumps on Guix System

bug#58923: Malformed core dumps on Guix System

[Mathieu Othacehe]

Hello,

Working on https://issues.guix.gnu.org/58733, I noticed that there is
something wrong with the core dumps we are generating on Guix System.

--8<---------------cut here---------------start------------->8---
mathieu@meije ~/tmp [env]$ cat test.c 
#include <stdio.h>
int main() {
	int *t = NULL;
	return *t;
}

mathieu@meije ~/tmp [env]$ gcc test.c 
mathieu@meije ~/tmp [env]$ ulimit -c unlimited
mathieu@meije ~/tmp [env]$ ulimit -a
real-time non-blocking time  (microseconds, -R) unlimited
core file size              (blocks, -c) unlimited

mathieu@meije ~/tmp [env]$ echo "/tmp/my-core-%p" | sudo tee /proc/sys/kernel/core_pattern
/tmp/my-core-%p

mathieu@meije ~/tmp [env]$ ./a.out 
Segmentation fault (core dumped)

mathieu@meije ~/tmp [env]$ gdb ./a.out /tmp/my-core-5622
...
BFD: warning: /tmp/my-core-5622 has a segment extending past end of file
...
Failed to read a valid object file image from memory.
Core was generated by `./a.out'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000401102 in main ()
(gdb) bt
#0  0x0000000000401102 in main ()
Backtrace stopped: Cannot access memory at address 0x7fff14e14168
--8<---------------cut here---------------end--------------->8---

The "has a segment extending past end of file" warning appears to be
problematic and the "bt" command does not work which makes core dump
generation a bit useless.

Thanks,

Mathieu

bug#58923: Malformed core dumps on Guix System

[Ludovic Courtès]

Hi,

Mathieu Othacehe <othacehe@gnu.org> skribis:

> mathieu@meije ~/tmp [env]$ gdb ./a.out /tmp/my-core-5622
> ...
> BFD: warning: /tmp/my-core-5622 has a segment extending past end of file
> ...
> Failed to read a valid object file image from memory.

I never encountered that issue, although I’ve had to look a lot at core
dumps over time.  :-)

--8<---------------cut here---------------start------------->8---
$ gcc test.c
$ ulimit -c unlimited 
$ ./a.out
Segmentation fault (core dumped)
$ gdb a.out core
GNU gdb (GDB) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...
(No debugging symbols found in a.out)
[New LWP 23407]
Core was generated by `./a.out'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000401106 in main ()
(gdb) bt
#0  0x0000000000401106 in main ()
(gdb) quit
--8<---------------cut here---------------end--------------->8---

Could it have to do with /proc/sys/kernel/core_pattern or with the fact
that your /tmp file system was full or something?  What if you try to
have the core dump on another file system?

Thanks,
Ludo’.

bug#58923: Malformed core dumps on Guix System

[Mathieu Othacehe]

Hey,

> Could it have to do with /proc/sys/kernel/core_pattern or with the fact
> that your /tmp file system was full or something?  What if you try to
> have the core dump on another file system?

I suspected that at first, but I then reproduced it on Berlin so I would
rather bet on a recent regression. I'll see if this can be reproduced on
a foreign distribution.

Thanks,

Mathieu

bug#58923: Malformed core dumps on Guix System

[zimoun]

Hi,

On mer., 02 nov. 2022 at 12:25, Mathieu Othacehe <othacehe@gnu.org> wrote:

>                                    I'll see if this can be reproduced on
> a foreign distribution.

Using Guix 00ff6f7.

--8<---------------cut here---------------start------------->8---
$ uname -a
Linux pfiuh07 5.13.0-40-generic #45~20.04.1-Ubuntu SMP Mon Apr 4 09:38:31 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

$ echo "/tmp/my-core-%p" | sudo tee /proc/sys/kernel/core_pattern
/tmp/my-core-%p

$ guix shell -C coreutils gcc-toolchain gdb

/tmp/bug-58923 [env]$ cat test.c
#include <stdio.h>
int main() {
        int *t = NULL;
        return *t;
}
/tmp/bug-58923 [env]$ gcc test.c

/tmp/bug-58923 [env]$ ulimit -a
real-time non-blocking time  (microseconds, -R) unlimited
core file size              (blocks, -c) 0
data seg size               (kbytes, -d) unlimited
scheduling priority                 (-e) 0
file size                   (blocks, -f) unlimited
pending signals                     (-i) 255927
max locked memory           (kbytes, -l) 65536
max memory size             (kbytes, -m) unlimited
open files                          (-n) 1024
pipe size                (512 bytes, -p) 8
POSIX message queues         (bytes, -q) 819200
real-time priority                  (-r) 0
stack size                  (kbytes, -s) 9788
cpu time                   (seconds, -t) unlimited
max user processes                  (-u) 255927
virtual memory              (kbytes, -v) unlimited
file locks                          (-x) unlimited

/tmp/bug-58923 [env]$ ulimit -c unlimited
/tmp/bug-58923 [env]$ ulimit -a
real-time non-blocking time  (microseconds, -R) unlimited
core file size              (blocks, -c) unlimited
data seg size               (kbytes, -d) unlimited
scheduling priority                 (-e) 0
file size                   (blocks, -f) unlimited
pending signals                     (-i) 255927
max locked memory           (kbytes, -l) 65536
max memory size             (kbytes, -m) unlimited
open files                          (-n) 1024
pipe size                (512 bytes, -p) 8
POSIX message queues         (bytes, -q) 819200
real-time priority                  (-r) 0
stack size                  (kbytes, -s) 9788
cpu time                   (seconds, -t) unlimited
max user processes                  (-u) 255927
virtual memory              (kbytes, -v) unlimited
file locks                          (-x) unlimited

/tmp/bug-58923 [env]$ ./a.out
Segmentation fault (core dumped)

/tmp/bug-58923 [env]$ ls /tmp/
bug-58923  my-core-23

/tmp/bug-58923 [env]$ gdb ./a.out /tmp/my-core-23
GNU gdb (GDB) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./a.out...
(No debugging symbols found in ./a.out)
[New LWP 23]
Core was generated by `./a.out'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000401106 in main ()
(gdb) bt
#0  0x0000000000401106 in main ()
(gdb) exit
/tmp/bug-58923 [env]$ exit
exit
--8<---------------cut here---------------end--------------->8---


Cheers,
simon

bug#58923: Malformed core dumps on Guix System

[Mathieu Othacehe]

Hey zimoun,

> #0  0x0000000000401106 in main ()
> (gdb) bt
> #0  0x0000000000401106 in main ()
> (gdb) exit

OK so it must somehow be related to Guix System or the Linux kernel we
ship.

Thanks for your feedback,

Mathieu

bug#58923: Malformed core dumps on Guix System

[Ludovic Courtès]

Hi,

Mathieu Othacehe <othacehe@gnu.org> skribis:

> I suspected that at first, but I then reproduced it on Berlin so I would
> rather bet on a recent regression. I'll see if this can be reproduced on
> a foreign distribution.

I checked in a Guix System VM and cannot reproduce it either:

--8<---------------cut here---------------start------------->8---
$ guix describe
Generation 234	Nov 07 2022 00:27:58	(current)
  guix 4a34da8
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 4a34da845ed91821d38ba8a9b65ad650dd7488d1
$ $(guix system vm --no-graphic gnu/system/examples/bare-bones.tmpl) -m 1024
[…]
komputilo login: root
root
This is the GNU operating system, welcome!

root@komputilo ~# ulimit -c unlimited
ulimit -c unlimited
root@komputilo ~# guile -c '(use-modules (system foreign)) (dereference-pointer (make-pointer 1234))'
guile -c '(use-modules (system foreign)) (dereference-pointer (make-pointer 1234))'
[   17.580329] guile[188]: segfault at 4d2 ip 00007f53893ff97f sp 00007ffede6ab190 error 4 in libguile-3.0.so.1.5.0[7f53893dc000+c8000]
[   17.582412] Code: 66 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec 08 40 f6 c7 06 75 26 48 8b 07 83 e0 7f 48 83 f8 1f 75 1a 48 8b 47 08 48 85 c0 74 31 <48> 8b 38 31 f6 48 83 c4 08 e9 33 d1 fd ff 0f 1f 00 48 89 fa 48 8d
Segmentation fault (core dumped)
root@komputilo ~# uname -a
uname -a
Linux komputilo 6.0.7-gnu #1 SMP PREEMPT_DYNAMIC 1 x86_64 GNU/Linux
root@komputilo ~# echo "set debug-file-directory /gnu/store/9snhi90f2nivxqrvqgjgixdch5zkps88-guile-3.0.8-debug/lib/debug" >> ~/.gdbinit
echo "set debug-file-directory /gnu/store/9snhi90f2nivxqrvqgjgixdch5zkps88-guile-3.0.8-debug/lib/debug" >> ~/.gdbinit
root@komputilo ~# /gnu/store/8fg0nk7c0xylmb6vpz1hc2mx7k3nqw47-gdb-12.1/bin/gdb $(type -P guile) core
/gnu/store/8fg0nk7c0xylmb6vpz1hc2mx7k3nqw47-gdb-12.1/bin/gdb $(type -P guile) core
GNU gdb (GDB) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /run/current-system/profile/bin/guile...
Reading symbols from /gnu/store/9snhi90f2nivxqrvqgjgixdch5zkps88-guile-3.0.8-debug/lib/debug//gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/bin/guile.debug...
[New LWP 188]

warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
Core was generated by `guile -c (use-modules (system foreign)) (dereference-pointer (make-pointer 1234'.
Program terminated with signal SIGSEGV, Segmentation fault.
--Type <RET> for more, q to quit, c to continue without paging--

#0  scm_dereference_pointer (pointer=0x7f5388a3d4f0) at foreign.c:375
375	foreign.c: No such file or directory.
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm
WARNING: (guile-user): imported module (gdb) overrides core binding `symbol?'
;;; /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm:293:21: warning: possibly unbound variable `program-debug-info-name'
;;; /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm:326:10: warning: possibly unbound variable `find-source-for-addr'
;;; /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm:326:32: warning: possibly unbound variable `program-debug-info-addr'
;;; /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm:327:32: warning: possibly unbound variable `program-debug-info-context'
;;; compiled /root/.cache/guile/ccache/3.0-LE-8-4.5/gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/lib/libguile-3.0.so.1.5.0-gdb.scm.go
;;; compiling /gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/share/guile/3.0/system/base/types.scm
;;; compiled /root/.cache/guile/ccache/3.0-LE-8-4.5/gnu/store/qlmpcy5zi84m6dikq3fnx5dz38qpczlc-guile-3.0.8/share/guile/3.0/system/base/types.scm.go
(gdb) bt
bt
#0  scm_dereference_pointer (pointer=#<pointer 0x4d2>) at foreign.c:375
#1  0x00007f5389478326 in vm_regular_engine (thread=0x7f5388913d80)
    at vm-engine.c:972
#2  0x00007f53894855d9 in scm_call_n (proc=<optimized out>, 
    argv=<optimized out>, nargs=1) at vm.c:1610
#3  0x00007f53893ed457 in scm_primitive_eval (exp=<optimized out>, 
    exp@entry=(dereference-pointer (make-pointer 1234))) at eval.c:671
#4  0x00007f53893f34b6 in scm_eval (
    exp=(dereference-pointer (make-pointer 1234)), 
    module_or_state="#<struct module>" = {...}) at eval.c:705
#5  0x00007f5389478326 in vm_regular_engine (thread=0x7f5388913d80)
    at vm-engine.c:972
#6  0x00007f53894855d9 in scm_call_n (proc=<optimized out>, 
    argv=<optimized out>, nargs=1) at vm.c:1610
#7  0x00007f53893ed457 in scm_primitive_eval (exp=<optimized out>, 
    exp@entry=((@ (ice-9 control) %) (begin ((@@ (ice-9 command-line) eval-string/lang) "(use-modules (system foreign)) (dereference-pointer (make-pointer 1234))") (quit)))) at eval.c:671
#8  0x00007f53893f34b6 in scm_eval (
    exp=((@ (ice-9 control) %) (begin ((@@ (ice-9 command-line) eval-string/lang) "(use-modules (system foreign)) (dereference-pointer (make-pointer 1234))") (quit))), module_or_state="#<struct module>" = {...}) at eval.c:705
#9  0x00007f53894573b6 in scm_shell (argc=3, argv=0x7ffede6abb48)
--Type <RET> for more, q to quit, c to continue without paging--

    at script.c:357
#10 0x00007f538940249c in invoke_main_func (body_data=0x7ffede6aba00)
    at init.c:312
#11 0x00007f53893eb85a in c_body (d=0x7ffede6ab920) at continuations.c:430
#12 0x00007f5389478326 in vm_regular_engine (thread=0x7f5388913d80)
    at vm-engine.c:972
#13 0x00007f53894855d9 in scm_call_n (proc=<optimized out>, 
    argv=<optimized out>, nargs=2) at vm.c:1610
#14 0x00007f53893ed09a in scm_call_2 (proc=<optimized out>, 
    arg1=<optimized out>, arg2=<optimized out>) at eval.c:503
#15 0x00007f53894a3742 in scm_c_with_exception_handler.constprop.0 (type=#t, 
    handler_data=handler_data@entry=0x7ffede6ab8b0, 
    thunk_data=thunk_data@entry=0x7ffede6ab8b0, thunk=<optimized out>, 
    handler=<optimized out>) at exceptions.c:170
#16 0x00007f538947588f in scm_c_catch (tag=<optimized out>, 
    body=<optimized out>, body_data=<optimized out>, handler=<optimized out>, 
    handler_data=<optimized out>, pre_unwind_handler=<optimized out>, 
    pre_unwind_handler_data=0x7f5388991040) at throw.c:168
#17 0x00007f53893ede66 in scm_i_with_continuation_barrier (
    pre_unwind_handler=0x7f53893edb80 <pre_unwind_handler>, 
    pre_unwind_handler_data=0x7f5388991040, handler_data=0x7ffede6ab920, 
    handler=0x7f53893f48b0 <c_handler>, body_data=0x7ffede6ab920, 
    body=0x7f53893eb850 <c_body>) at continuations.c:368
--Type <RET> for more, q to quit, c to continue without paging--

#18 scm_c_with_continuation_barrier (func=<optimized out>, 
    data=<optimized out>) at continuations.c:464
#19 0x00007f5389474b39 in with_guile (base=0x7ffede6ab9a8, data=0x7ffede6ab9d0)
    at threads.c:645
#20 0x00007f538934b0ba in GC_call_with_stack_base ()
   from /gnu/store/2lczkxbdbzh4gk7wh91bzrqrk7h5g1dl-libgc-8.0.4/lib/libgc.so.1
#21 0x00007f538946d8b8 in scm_i_with_guile (dynamic_state=<optimized out>, 
    data=<optimized out>, func=<optimized out>) at threads.c:688
#22 scm_with_guile (func=<optimized out>, data=<optimized out>)
    at threads.c:694
#23 0x00007f538940b025 in scm_boot_guile (argc=argc@entry=3, 
    argv=argv@entry=0x7ffede6abb48, 
    main_func=main_func@entry=0x401230 <inner_main>, closure=closure@entry=0x0)
    at init.c:295
#24 0x00000000004010f7 in main (argc=3, argv=0x7ffede6abb48) at guile.c:94
(gdb) 
--8<---------------cut here---------------end--------------->8---

Would be good to isolate the circumstances that can cause the problem.

Ludo’.

bug#58923: Malformed core dumps on Guix System

[Mathieu Othacehe]

Hey,

Thanks for trying to reproduce it. Turns out, it is now working both on
Berlin and on installation images but still failing on my machine. It's
not often that those kind of issues do resolve by themselves. I would
suspect a kernel regression here.

My machine has the following kernel:
Linux meije 5.19.15 #1 SMP PREEMPT_DYNAMIC 1 x86_64 GNU/Linux 

while Berlin and installation images have respectively:
Linux berlin.guix.gnu.org 6.0.7-gnu #1 SMP PREEMPT_DYNAMIC 1 x86_64 GNU/Linux
Linux gnu 6.0.7-gnu #1 SMP PREEMPT_DYNAMIC 1 x86_64 GNU/Linux

Anyway, we can now:

--8<---------------cut here---------------start------------->8---
wget https://dump.guix.gnu.org/download/installer-dump-1c97b34e
tar -xvf installer-dump-1c97b34e
cd dump.2022-10-14.17.15.30
gdb $(type -P guile) core-dump
(gdb) bt
#0  linux_destroy (dev=0x268e620) at arch/linux.c:1615
#1  0x00007fee6ae9cd37 in chained_finalizer (obj=0x7fee54779370, data=0x7fee6790acc0) at finalizers.c:84
#2  0x00007fee6adf5e3f in GC_invoke_finalizers () at extra/../finalize.c:1281
#3  0x00007fee6ae9d429 in scm_run_finalizers () at finalizers.c:414
#4  0x00007fee6aea4482 in finalization_thread_proc (unused=<optimized out>) at finalizers.c:244
#5  0x00007fee6ae9085a in c_body (d=0x7fee69f21d80) at continuations.c:430
#6  0x00007fee6af1d326 in vm_regular_engine (thread=0x7fee6a3b8b40) at vm-engine.c:972
#7  0x00007fee6af2a5d9 in scm_call_n (proc=<optimized out>, argv=<optimized out>, nargs=2) at vm.c:1610
#8  0x00007fee6ae9209a in scm_call_2 (proc=<optimized out>, arg1=<optimized out>, arg2=<optimized out>) at eval.c:503
#9  0x00007fee6af48742 in scm_c_with_exception_handler.constprop.0 (type=#t, handler_data=handler_data@entry=0x7fee69f21d10, thunk_data=thunk_data@entry=0x7fee69f21d10, thunk=<optimized out>, handler=<optimized out>)
    at exceptions.c:170
#10 0x00007fee6af1a88f in scm_c_catch (tag=<optimized out>, body=<optimized out>, body_data=<optimized out>, handler=<optimized out>, handler_data=<optimized out>, pre_unwind_handler=<optimized out>, 
    pre_unwind_handler_data=0x7fee6a436040) at throw.c:168
#11 0x00007fee6ae92e66 in scm_i_with_continuation_barrier (pre_unwind_handler=0x7fee6ae92b80 <pre_unwind_handler>, pre_unwind_handler_data=0x7fee6a436040, handler_data=0x7fee69f21d80, handler=0x7fee6ae998b0 <c_handler>, 
    body_data=0x7fee69f21d80, body=0x7fee6ae90850 <c_body>) at continuations.c:368
#12 scm_c_with_continuation_barrier (func=<optimized out>, data=<optimized out>) at continuations.c:464
#13 0x00007fee6af19b39 in with_guile (base=0x7fee69f21e08, data=0x7fee69f21e30) at threads.c:645
#14 0x00007fee6adf00ba in GC_call_with_stack_base (fn=fn@entry=0x7fee6af19a60 <with_guile>, arg=arg@entry=0x7fee69f21e30) at extra/../misc.c:2106
#15 0x00007fee6af128b8 in scm_i_with_guile (dynamic_state=<optimized out>, data=<optimized out>, func=<optimized out>) at threads.c:688
#16 scm_with_guile (func=<optimized out>, data=<optimized out>) at threads.c:694
#17 0x00007fee6adc6d7e in ?? () from /gnu/store/5h2w4qi9hk1qzzgi1w83220ydslinr4s-glibc-2.33/lib/libpthread.so.0
#18 0x00007fee6a9c4eff in clone () from /gnu/store/5h2w4qi9hk1qzzgi1w83220ydslinr4s-glibc-2.33/lib/libc.so.6
--8<---------------cut here---------------end--------------->8---

which feels quite nice.

Closing that one.

Thanks,

Mathieu

bug#58923: Malformed core dumps on Guix System

[Maxim Cournoyer]

Hi,

Mathieu Othacehe <othacehe@gnu.org> writes:

> Anyway, we can now:
>
> wget https://dump.guix.gnu.org/download/installer-dump-1c97b34e
> tar -xvf installer-dump-1c97b34e
> cd dump.2022-10-14.17.15.30
> gdb $(type -P guile) core-dump
> (gdb) bt
> #0  linux_destroy (dev=0x268e620) at arch/linux.c:1615
> #1  0x00007fee6ae9cd37 in chained_finalizer (obj=0x7fee54779370, data=0x7fee6790acc0) at finalizers.c:84
> #2  0x00007fee6adf5e3f in GC_invoke_finalizers () at extra/../finalize.c:1281
> #3  0x00007fee6ae9d429 in scm_run_finalizers () at finalizers.c:414
> #4  0x00007fee6aea4482 in finalization_thread_proc (unused=<optimized out>) at finalizers.c:244
> #5  0x00007fee6ae9085a in c_body (d=0x7fee69f21d80) at continuations.c:430
> #6  0x00007fee6af1d326 in vm_regular_engine (thread=0x7fee6a3b8b40) at vm-engine.c:972
> #7  0x00007fee6af2a5d9 in scm_call_n (proc=<optimized out>, argv=<optimized out>, nargs=2) at vm.c:1610
> #8  0x00007fee6ae9209a in scm_call_2 (proc=<optimized out>, arg1=<optimized out>, arg2=<optimized out>) at eval.c:503
> #9  0x00007fee6af48742 in scm_c_with_exception_handler.constprop.0 (type=#t, handler_data=handler_data@entry=0x7fee69f21d10, thunk_data=thunk_data@entry=0x7fee69f21d10, thunk=<optimized out>, handler=<optimized out>)
>     at exceptions.c:170
> #10 0x00007fee6af1a88f in scm_c_catch (tag=<optimized out>, body=<optimized out>, body_data=<optimized out>, handler=<optimized out>, handler_data=<optimized out>, pre_unwind_handler=<optimized out>, 
>     pre_unwind_handler_data=0x7fee6a436040) at throw.c:168
> #11 0x00007fee6ae92e66 in scm_i_with_continuation_barrier (pre_unwind_handler=0x7fee6ae92b80 <pre_unwind_handler>, pre_unwind_handler_data=0x7fee6a436040, handler_data=0x7fee69f21d80, handler=0x7fee6ae998b0 <c_handler>, 
>     body_data=0x7fee69f21d80, body=0x7fee6ae90850 <c_body>) at continuations.c:368
> #12 scm_c_with_continuation_barrier (func=<optimized out>, data=<optimized out>) at continuations.c:464
> #13 0x00007fee6af19b39 in with_guile (base=0x7fee69f21e08, data=0x7fee69f21e30) at threads.c:645
> #14 0x00007fee6adf00ba in GC_call_with_stack_base (fn=fn@entry=0x7fee6af19a60 <with_guile>, arg=arg@entry=0x7fee69f21e30) at extra/../misc.c:2106
> #15 0x00007fee6af128b8 in scm_i_with_guile (dynamic_state=<optimized out>, data=<optimized out>, func=<optimized out>) at threads.c:688
> #16 scm_with_guile (func=<optimized out>, data=<optimized out>) at threads.c:694
> #17 0x00007fee6adc6d7e in ?? () from /gnu/store/5h2w4qi9hk1qzzgi1w83220ydslinr4s-glibc-2.33/lib/libpthread.so.0
> #18 0x00007fee6a9c4eff in clone () from /gnu/store/5h2w4qi9hk1qzzgi1w83220ydslinr4s-glibc-2.33/lib/libc.so.6
>
> which feels quite nice.

Very nice!  I'm sure that'll be very valuable.

-- 
Thanks,
Maxim