mount - How do I remount a filesystem read/write? - Ask Ubuntu
askubuntu.com › questions › 712443@Hi-Angel: Yes, kos and I did exactly that, with removed partition identifier. When I (as root) run mount -o remount,rw /, that program (/bin/mount) figures out the partition identifier by itself, and attempts the system call mount("/dev/sda7", "/", 0x19f6590, MS_MGC_VAL|MS_REMOUNT, "errors=remount-ro"), which returns -1 EINVAL (Invalid argument), and then it prints mount: / not mounted or bad ...