What were you trying to do that didn't work?

• cannot collect application core

Jul 14 16:56:15 testhost systemd-coredump[12714]: Failed to send coredump datagram: No buffer space available
Jul 14 16:56:15 testhost systemd[1]: Started Process Core Dump (PID 12714/UID 0).
Jul 14 16:56:15 testhost systemd-coredump[12715]: Coredump file descriptor missing.
Jul 14 16:56:15 testhost systemd[1]: systemd-coredump@1-12714-0.service: Deactivated successfully.

What is the impact of this issue to you?

• core dumps fail

Please provide the package NVR for which the bug is seen:

• systemd-252-32.el9_4.x86_64

How reproducible is this bug?:

• by customer

Steps to reproduce

1. unsure. Reproducer attempt failed

Expected results

• core dump should not fail

Actual results

• core dump fails

Reproducer attempt:

• We attempted to reproduce this by setting the buffer sizes to be unreasonably small.

  # sysctl -w net.core.wmem_default=8192 net.core.rmem_default=4096
  net.core.wmem_default=8192
  net.core.rmem_default=4096
  
  # ./files 100000 100
  sleeping 100 seconds
  Segmentation fault (core dumped)
  
  # kill -11 $(pidof files)
  
  # journalctl | tail
  Jul 11 09:13:39 test-rhel9.local systemd[1]: Created slice Slice /system/systemd-coredump.
  Jul 11 09:13:39 test-rhel9.local systemd[1]: Started Process Core Dump (PID 1660/UID 0).
  Jul 11 09:13:39 test-rhel9.local systemd-coredump[1661]: Process 1658 (files) of user 0 dumped core.
                                                               
                                                               Stack trace of thread 1658:
                                                               #0  0x00007fd22f0d461a clock_nanosleep@GLIBC_2.2.5 (libc.so.6 + 0xd461a)
                                                               #1  0x00007fd22f0d9247 __nanosleep (libc.so.6 + 0xd9247)
                                                               #2  0x00007fd22f0d917e sleep (libc.so.6 + 0xd917e)
                                                               #3  0x0000000000401306 n/a (/root/coredump/files + 0x1306)
                                                               #4  0x00007fd22f0295d0 __libc_start_call_main (libc.so.6 + 0x295d0)
                                                               #5  0x00007fd22f029680 __libc_start_main@@GLIBC_2.34 (libc.so.6 + 0x29680)
                                                               #6  0x00000000004010d5 n/a (/root/coredump/files + 0x10d5)
                                                               ELF object binary architecture: AMD x86-64
  Jul 11 09:13:39 test-rhel9.local systemd[1]: systemd-coredump@0-1660-0.service: Deactivated successfully.
  
  # coredumpctl list
  TIME                          PID UID GID SIG     COREFILE EXE                  SIZE
  Fri 2025-07-11 09:13:39 AEST 1658   0   0 SIGSEGV present  /root/coredump/files 1.2M