So that's what I get out of gdb (which is not a lot):

Reading symbols from /usr/bin/fwupdmgr...
Reading symbols from /usr/lib/debug/.build-id/d6/46e7a195bae49c7dcf1cd43104b1b9390b8b0d.debug...

warning: Can't open file /usr/lib/s390x-linux-gnu/libgmodule-2.0.so.0.7200.1 during file-backed mapping note processing

warning: Can't open file /usr/lib/s390x-linux-gnu/libglib-2.0.so.0.7200.1 during file-backed mapping note processing

warning: Can't open file /usr/lib/s390x-linux-gnu/libgobject-2.0.so.0.7200.1 during file-backed mapping note processing

warning: Can't open file /usr/lib/s390x-linux-gnu/libgio-2.0.so.0.7200.1 during file-backed mapping note processing
[New LWP 7393]
[New LWP 7394]

warning: .dynamic section for "/lib/s390x-linux-gnu/libicuuc.so.70" is not at the expected address (wrong library or version mismatch?)

warning: .dynamic section for "/lib/s390x-linux-gnu/libicudata.so.70" is not at the expected address (wrong library or version mismatch?)
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/s390x-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/bin/fwupdmgr refresh'.
Program terminated with signal SIGTRAP, Trace/breakpoint trap.
--Type <RET> for more, q to quit, c to continue without paging--c
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=<optimized out>, no_tid=no_tid@entry=0) at pthread_kill.c:44
44	pthread_kill.c: No such file or directory.
[Current thread is 1 (Thread 0x3ff932d9a80 (LWP 7393))]
(gdb) bt
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=<optimized out>, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x000003ff92798146 in __pthread_kill_internal (signo=<optimized out>, threadid=<optimized out>) at pthread_kill.c:78
#2  0x000003ff92748aa0 in __GI_raise (sig=<optimized out>) at ../sysdeps/posix/raise.c:26
#3  0x000003ff92ce12de in g_log_default_handler () from /lib/s390x-linux-gnu/libglib-2.0.so.0
#4  0x000003ff92ce2864 in g_logv () from /lib/s390x-linux-gnu/libglib-2.0.so.0
#5  0x000003ff92ce2b0a in g_log () from /lib/s390x-linux-gnu/libglib-2.0.so.0
#6  0x000003ff92f84d5e in ?? () from /lib/s390x-linux-gnu/libgio-2.0.so.0
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

[Just notice that this happened under extreme high load conditions.]


And btw, what I see now at the test system, running the patched package is:

Aug 22 19:39:00 zlin systemd[1]: Starting Refresh fwupd metadata and update motd...
Aug 22 19:39:00 zlin  dbus-daemon[706]: [system] Activating via systemd: service name='org.freedesktop.fwupd' unit='fwupd.service' requested by ':1.125' (uid=112 pid=40813 comm="/usr/bin/fwupdmgr refresh " label="unconfined")
Aug 22 19:39:00 zlin fwupd[40819]: 19:39:00:0868 FuContext            Failed to load SMBIOS: neither SMBIOS or DT found
Aug 22 19:39:00 zlin  dbus-daemon[706]: [system] Successfully activated service 'org.freedesktop.fwupd'
Aug 22 19:39:00 zlin fwupdmgr[40813]: Updating lvfs
Aug 22 19:39:00 zlin fwupdmgr[40813]: Downloading…: 0%
Aug 22 19:40:00 zlin systemd[1]: fwupd-refresh.service: Main process exited, code=exited, status=1/FAILURE
Aug 22 19:40:00 zlin systemd[1]: fwupd-refresh.service: Failed with result 'exit-code'.
Aug 22 19:40:00 zlin systemd[1]: Failed to start Refresh fwupd metadata and update motd.
Aug 22 21:39:00 zlin systemd[1]: fwupd.service: Deactivated successfully.