Both ramfs and tmpfs on Linux cause writes directly to the page cache, just like a normal write but without a backing store (though in tmpfs' case, the backing

Both ramfs and tmpfs on Linux cause writes directly to the page cache, just like a normal write but without a backing store (though in tmpfs' case, the backing store is swap). So there is no double RAM usage. This is confirmed in these docs: Documentation/filesystems/ramfs-rootfs-initramfs.txt Documentation/filesystems/tmpfs.txt