runaway avocado

[Peter Maydell]

So, I somehow ended up with this process still running on my
local machine after a (probably failed) 'make check-acceptance':

petmay01 13710 99.7  3.7 2313448 1235780 pts/16 Sl  16:10 378:00
./qemu-system-aarch64 -display none -vga none -chardev
socket,id=mon,path=/var/tmp/tmp5szft2yi/qemu-13290-monitor.sock -mon
chardev=mon,mode=control -machine virt -chardev
socket,id=console,path=/var/tmp/tmp5szft2yi/qemu-13290-console.sock,server,nowait
-serial chardev:console -icount
shift=7,rr=record,rrfile=/var/tmp/avocado_iv8dehpo/avocado_job_w9efukj5/32-tests_acceptance_reverse_debugging.py_ReverseDebugging_AArch64.test_aarch64_virt/replay.bin,rrsnapshot=init
-net none -drive
file=/var/tmp/avocado_iv8dehpo/avocado_job_w9efukj5/32-tests_acceptance_reverse_debugging.py_ReverseDebugging_AArch64.test_aarch64_virt/disk.qcow2,if=none
-kernel 
/home/petmay01/avocado/data/cache/by_location/a00ac4ae676ef0322126abd2f7d38f50cc9cbc95/vmlinuz
-cpu cortex-a53

and it was continuing to log to a deleted file
/var/tmp/avocado_iv8dehpo/avocado_job_w9efukj5/32-tests_acceptance_reverse_debugging.py_ReverseDebugging_AArch64.test_aarch64_virt/replay.bin

which was steadily eating my disk space and got up to nearly 100GB
in used disk (invisible to du, of course, since it was an unlinked
file) before I finally figured out what was going on and killed it
about six hours later...

Any suggestions for how we might improve the robustness of the
relevant test ?

thanks
-- PMM