如何获取2MB/1GB大页（Hugepages）的物理地址？

我已仔细研究过相关问题及参考资料，但未能解决问题，故再次提问。

我了解通过/proc/self/pagemap获取物理地址的方法，大致分为两步：1. 获取物理页；2. 获取页偏移。

uint64_t get_page_frame_number_of_address(void *address) {

    /* Open the pagemap file for the current process */
    FILE *pagemap = fopen("/proc/self/pagemap", "rb");

    /* Seek to the page that the buffer is on it */ 
    uint64_t offset = (uint64_t)((uint64_t)address >> PAGE_SHIFT) * (uint64_t)PAGEMAP_LENGTH;
    if(fseek(pagemap, (uint64_t)offset, SEEK_SET) != 0) {
        fprintf(stderr, "Failed to seek pagemap to proper location\n");
        exit(1);
    }

    /* The page frame number is in bits 0-54 so read the first 7 bytes and clear the 55th bit */
    uint64_t page_frame_number = 0;
    fread(&page_frame_number, 1, PAGEMAP_LENGTH-1, pagemap);
    page_frame_number &= 0x7FFFFFFFFFFFFF;
    fclose(pagemap);
    return page_frame_number;
}

uint64_t get_physical_address(void* address) {

    /* Get page frame number */
    unsigned int page_frame_number = get_page_frame_number_of_address(address);

    /* Find the difference from the buffer to the page boundary */
    uint64_t distance_from_page_boundary = (uint64_t)address % getpagesize();

    /* Determine how far to seek into memory to find the buffer */
    uint64_t physical_address = (uint64_t)((uint64_t)page_frame_number << PAGE_SHIFT) + (uint64_t)distance_from_page_boundary;

    return physical_address;
}

我尝试将PAGE_SHIFT从12（对应4KB页）改为21（对应2MB页），并调整getpagesize()的大小，但此时page_frame_number始终为0。因此我想知道：

• 是否无法通过/proc/self/pagemap获取大页的物理地址？
• 还有其他获取大页物理地址的方法吗？

内容的提问来源于stack exchange，提问作者xuxing chen