Hi, since I have regular access to a s390x box I was able to test a few more (Ubuntu centric) versions and can confirm that I do not see such a hang. Hope these data points might help.
Tested qemu-img: - 1:7.2+dfsg-2ubuntu1~lunarppa1 - 1:6.2+dfsg-2ubuntu6.6 Under Kernel 5.15.0-60-generic All done on a real disk, not tmpfs. Since it hangs, what do strace and/or gdb report where it is stuck? Also to start with - is it continuing to consume cpu cycles or just stuck?