MADV_HUGEPAGE works with file-mapped memory since Linux 5.4

[ruihe774]

According to the man page of madvise, MADV_HUGEPAGE works with file-mapped memory since Linux 5.4:

Since Linux 5.4, automatic scan of eligible areas and replacement by huge pages works with private anonymous pages
(see mmap(2)), shmem pages, and file-backed pages. For all memory types, memory may only be replaced by huge
pages on hugepage-aligned boundaries. For file-mapped memory —including tmpfs (see tmpfs(2))— the mapping must
also be naturally hugepage-aligned within the file. Additionally, for file-backed, non-tmpfs memory, the file
must not be open for write and the mapping must be executable.

which contradicts current doc of Advice::HugePage:

/// Enable Transparent Huge Pages (THP) for pages in the range
/// specified by addr and length. Currently, Transparent Huge
/// Pages work only with private anonymous pages (see
/// mmap(2)).