I was migrating my desktop from spinning disks to ssd:s.
To expedite this i booted the machine (using dracut and) rd.break...
However, i got in to a state where systemd refused to let me mount certain filesystems - it IMMEDIATELY unmounted it. This included remount,rw since i needed access to some files.
I assume that this behavior is either a bug or a "security feature"... Please look in to it since this is the most annoying recovery i have ever had to do.
*** This bug has been marked as a duplicate of bug 89383 ***