finally, a nit: GNU/Linux-libre refers to a category of operating systems and distributions thereof, that use GNU's liberated version of Linux (named GNU Linux-libre) as the kernel underneath the GNU operating system's userland.
like any distribution of GNU, the fact that it uses GNU as the operating system does not in itself guarantee that it is Free Software: it is unfortunately common for GNU distributions to bundle nonfree, user-subjugating components, from firmware to applications. this is not quite so common for distributions that reject the nonfree parts of Linux and use GNU Linux-libre instead, so GNU/Linux-libre (the combination of GNU userland with GNU Linux-libre kernel) does indeed suggest the distro is likely wholly (holy? :-) free, but it can't really be taken for granted.

I *think* what you meant in your post was to refer to the kernel only; whose distribution does indeed aim to be entirely Free Software, as that's its raison d'être. but to refer to the kernel alone, the slash shouldn't be there: that modified kernel can be referred as Linux-libre or, as we've more recently become part of the GNU project, GNU Linux-libre. here, GNU is used as a qualifier, that in other packages serves to distinguish from other suppliers of programs with similar technical purposes (think GNU libc vs other C libraries, or GNU GPL vs other licenses for the general public), unlike GNU/Linux, where two separate projects combine to form a whole operating system