According to the man page (http://man7.org/linux/man-pages/man2/madvise.2.html) for madvise under "Linux notes"

The Linux implementation requires that the address addr be page-aligned...

In utils/s2n_mem.c madvise is called:

madvise(b->data, size, MADV_DONTDUMP)

(b->)data is created using realloc, witch does not guarantee page alignment.

Further the man page says the following errno will be returned in the following situation:

EINVAL addr is not page-aligned or length is negative.

The current implementation can fail on Linux.