ramfs file systems cannot be limited in size like a disk base file system which is limited by it’s capacity. ramfs will continue using memory storage until the system runs out of RAM and likely crashes or becomes unresponsive. This is a problem if the application writing to the file system cannot be limited in total size. Another issue is you cannot see the size of the file system in df and it can only be estimated by looking at the cached entry in free.
The Difference Between a tmpfs and ramfs RAM Disk – JamesCoyle.net Limited
How to make tmpfs to use only the physical RAM and not the swap? - Unix & Linux Stack Exchange
