无法通过 move_pages(） 进行查询

#include <cstdint>
#include <iostream>
#include <numaif.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <limits>
int main(int argc, char** argv) {
    const constexpr uint64_t size = 16lu * 1024 * 1024;
    const constexpr uint32_t nPages = size / (4lu * 1024 * 1024);
    int32_t status[nPages];
    std::fill_n(status, nPages, std::numeric_limits<int32_t>::min());
    void* pages[nPages];
    auto fd = shm_open("test_shm", O_RDWR|O_CREAT, 0666);
    void* ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if (ptr == MAP_FAILED) {
        if (fd > 0) close(fd);
        throw "failed to map hugepages";
    }
    for (uint32_t i = 0; i < nPages; i++) {
        pages[i] = (char*)ptr + 4 * 1024 * 1024;
    }
    if (0 != move_pages(0, nPages, pages, nullptr, status, 0)) {
        std::cout << "failed to inquiry pages because " << strerror(errno) << std::endl;
    }
    else {
            for (uint32_t i = 0; i < nPages; i++) {
            std::cout << "page # " << i << " locates at numa node " << status[i] << std::endl;
        }
    }
    munmap(ptr, size);
    close(fd);
}

它打印：

page # 0 locates at numa node -2
page # 1 locates at numa node -2
page # 2 locates at numa node -2
page # 3 locates at numa node -2

根据手册页，它指出：

nodes is an array of integers that specify the desired location for each page.
Each element in the array is a node number. nodes can also be NULL, in which 
case move_pages() does not move any pages but instead will return the node where 
each page currently resides, in the status array. Obtaining the status of each 
page may be necessary to determine pages that need to be moved.

为什么在查询返回成功时打印负值？ 我的机器只有 2 个 NUMA - 0 和 1。

内核版本：3.10.0-862.2.3.el7.x86_64

这是大页面的版本：

#include <cstdint>
#include <iostream>
#include <numaif.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <limits>
int main(int argc, char** argv) {
        const int32_t dst_node = strtoul(argv[1], nullptr, 10);
        const constexpr uint64_t size = 4lu * 1024 * 1024;
        const constexpr uint64_t pageSize = 2lu * 1024 * 1024;
        const constexpr uint32_t nPages = size / pageSize;
        int32_t status[nPages];
        std::fill_n(status, nPages, std::numeric_limits<int32_t>::min());
        void* pages[nPages];
        int32_t dst_nodes[nPages];
        void* ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1, 0);
        if (ptr == MAP_FAILED) {
                throw "failed to map hugepages";
        }
        memset(ptr, 0x41, nPages*pageSize);
        for (uint32_t i = 0; i < nPages; i++) {
                pages[i] = &((char*)ptr)[i*pageSize];
                dst_nodes[i] = dst_node;
        }
        std::cout << "Before moving" << std::endl;
        if (0 != move_pages(0, nPages, pages, nullptr, status, 0)) {
            std::cout << "failed to inquiry pages because " << strerror(errno) << std::endl;
        }
        else {
                for (uint32_t i = 0; i < nPages; i++) {
                        std::cout << "page # " << i << " locates at numa node " << status[i] << std::endl;
                }
        }
        // real move
        if (0 != move_pages(0, nPages, pages, dst_nodes, status, MPOL_MF_MOVE_ALL)) {
                std::cout << "failed to move pages because " << strerror(errno) << std::endl;
                exit(-1);
        }
        const constexpr uint64_t smallPageSize = 4lu * 1024;
        const constexpr uint32_t nSmallPages = size / smallPageSize;
        void* smallPages[nSmallPages];
        int32_t smallStatus[nSmallPages] = {std::numeric_limits<int32_t>::min()};
        for (uint32_t i = 0; i < nSmallPages; i++) {
                smallPages[i] = &((char*)ptr)[i*smallPageSize];
        }

        std::cout << "after moving" << std::endl;
        if (0 != move_pages(0, nSmallPages, smallPages, nullptr, smallStatus, 0)) {
            std::cout << "failed to inquiry pages because " << strerror(errno) << std::endl;
        }
        else {
                for (uint32_t i = 0; i < nSmallPages; i++) {
                        std::cout << "page # " << i << " locates at numa node " << smallStatus[i] << std::endl;
                }
        }
}

有趣的是，move_pages()似乎理解巨大的页面，因为在移动巨大的页面后，我根据较小的页面大小进行查询，并填充预期的 NUMA ID。