According to the document, "libhugetlbfs can be used to make an existing application use hugepages for all its malloc() calls". And it is done through LD_PRELOAD environment variable.
LD_PRELOAD=libhugetlbfs.so HUGETLB_MORECORE=yes ./a.out
According to this article, this is done by using LD_PRELOAD to override dynamically linked functions with the same name. But I couldn't find a function named malloc in the source code of libhugetlbfs (https://github.com/search?q=repo%3Alibhugetlbfs%2Flibhugetlbfs+malloc&type=code&p=1).
How does it hook and override the origin malloc?