310 lines
6.8 KiB
C
310 lines
6.8 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* A test of splitting PMD THPs and PTE-mapped THPs from a specified virtual
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* address range in a process via <debugfs>/split_huge_pages interface.
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*/
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <inttypes.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/mount.h>
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#include <malloc.h>
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#include <stdbool.h>
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#include "vm_util.h"
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uint64_t pagesize;
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unsigned int pageshift;
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uint64_t pmd_pagesize;
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#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
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#define INPUT_MAX 80
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#define PID_FMT "%d,0x%lx,0x%lx"
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#define PATH_FMT "%s,0x%lx,0x%lx"
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#define PFN_MASK ((1UL<<55)-1)
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#define KPF_THP (1UL<<22)
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int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
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{
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uint64_t paddr;
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uint64_t page_flags;
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if (pagemap_file) {
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pread(pagemap_file, &paddr, sizeof(paddr),
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((long)vaddr >> pageshift) * sizeof(paddr));
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if (kpageflags_file) {
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pread(kpageflags_file, &page_flags, sizeof(page_flags),
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(paddr & PFN_MASK) * sizeof(page_flags));
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return !!(page_flags & KPF_THP);
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}
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}
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return 0;
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}
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static int write_file(const char *path, const char *buf, size_t buflen)
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{
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int fd;
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ssize_t numwritten;
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fd = open(path, O_WRONLY);
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if (fd == -1)
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return 0;
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numwritten = write(fd, buf, buflen - 1);
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close(fd);
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if (numwritten < 1)
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return 0;
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return (unsigned int) numwritten;
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}
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static void write_debugfs(const char *fmt, ...)
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{
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char input[INPUT_MAX];
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int ret;
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va_list argp;
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va_start(argp, fmt);
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ret = vsnprintf(input, INPUT_MAX, fmt, argp);
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va_end(argp);
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if (ret >= INPUT_MAX) {
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printf("%s: Debugfs input is too long\n", __func__);
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exit(EXIT_FAILURE);
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}
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if (!write_file(SPLIT_DEBUGFS, input, ret + 1)) {
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perror(SPLIT_DEBUGFS);
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exit(EXIT_FAILURE);
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}
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}
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void split_pmd_thp(void)
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{
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char *one_page;
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size_t len = 4 * pmd_pagesize;
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size_t i;
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one_page = memalign(pmd_pagesize, len);
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if (!one_page) {
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printf("Fail to allocate memory\n");
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exit(EXIT_FAILURE);
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}
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madvise(one_page, len, MADV_HUGEPAGE);
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for (i = 0; i < len; i++)
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one_page[i] = (char)i;
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if (!check_huge_anon(one_page, 1, pmd_pagesize)) {
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printf("No THP is allocated\n");
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exit(EXIT_FAILURE);
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}
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/* split all THPs */
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write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
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(uint64_t)one_page + len);
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for (i = 0; i < len; i++)
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if (one_page[i] != (char)i) {
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printf("%ld byte corrupted\n", i);
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exit(EXIT_FAILURE);
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}
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if (check_huge_anon(one_page, 0, pmd_pagesize)) {
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printf("Still AnonHugePages not split\n");
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exit(EXIT_FAILURE);
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}
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printf("Split huge pages successful\n");
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free(one_page);
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}
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void split_pte_mapped_thp(void)
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{
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char *one_page, *pte_mapped, *pte_mapped2;
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size_t len = 4 * pmd_pagesize;
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uint64_t thp_size;
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size_t i;
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const char *pagemap_template = "/proc/%d/pagemap";
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const char *kpageflags_proc = "/proc/kpageflags";
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char pagemap_proc[255];
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int pagemap_fd;
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int kpageflags_fd;
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if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0) {
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perror("get pagemap proc error");
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exit(EXIT_FAILURE);
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}
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pagemap_fd = open(pagemap_proc, O_RDONLY);
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if (pagemap_fd == -1) {
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perror("read pagemap:");
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exit(EXIT_FAILURE);
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}
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kpageflags_fd = open(kpageflags_proc, O_RDONLY);
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if (kpageflags_fd == -1) {
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perror("read kpageflags:");
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exit(EXIT_FAILURE);
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}
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one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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madvise(one_page, len, MADV_HUGEPAGE);
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for (i = 0; i < len; i++)
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one_page[i] = (char)i;
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if (!check_huge_anon(one_page, 1, pmd_pagesize)) {
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printf("No THP is allocated\n");
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exit(EXIT_FAILURE);
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}
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/* remap the first pagesize of first THP */
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pte_mapped = mremap(one_page, pagesize, pagesize, MREMAP_MAYMOVE);
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/* remap the Nth pagesize of Nth THP */
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for (i = 1; i < 4; i++) {
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pte_mapped2 = mremap(one_page + pmd_pagesize * i + pagesize * i,
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pagesize, pagesize,
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MREMAP_MAYMOVE|MREMAP_FIXED,
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pte_mapped + pagesize * i);
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if (pte_mapped2 == (char *)-1) {
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perror("mremap failed");
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exit(EXIT_FAILURE);
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}
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}
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/* smap does not show THPs after mremap, use kpageflags instead */
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thp_size = 0;
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for (i = 0; i < pagesize * 4; i++)
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if (i % pagesize == 0 &&
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is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
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thp_size++;
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if (thp_size != 4) {
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printf("Some THPs are missing during mremap\n");
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exit(EXIT_FAILURE);
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}
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/* split all remapped THPs */
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write_debugfs(PID_FMT, getpid(), (uint64_t)pte_mapped,
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(uint64_t)pte_mapped + pagesize * 4);
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/* smap does not show THPs after mremap, use kpageflags instead */
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thp_size = 0;
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for (i = 0; i < pagesize * 4; i++) {
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if (pte_mapped[i] != (char)i) {
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printf("%ld byte corrupted\n", i);
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exit(EXIT_FAILURE);
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}
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if (i % pagesize == 0 &&
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is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
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thp_size++;
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}
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if (thp_size) {
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printf("Still %ld THPs not split\n", thp_size);
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exit(EXIT_FAILURE);
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}
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printf("Split PTE-mapped huge pages successful\n");
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munmap(one_page, len);
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close(pagemap_fd);
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close(kpageflags_fd);
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}
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void split_file_backed_thp(void)
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{
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int status;
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int fd;
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ssize_t num_written;
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char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
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const char *tmpfs_loc = mkdtemp(tmpfs_template);
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char testfile[INPUT_MAX];
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uint64_t pgoff_start = 0, pgoff_end = 1024;
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printf("Please enable pr_debug in split_huge_pages_in_file() if you need more info.\n");
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status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");
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if (status) {
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printf("Unable to create a tmpfs for testing\n");
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exit(EXIT_FAILURE);
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}
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status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
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if (status >= INPUT_MAX) {
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printf("Fail to create file-backed THP split testing file\n");
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goto cleanup;
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}
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fd = open(testfile, O_CREAT|O_WRONLY);
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if (fd == -1) {
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perror("Cannot open testing file\n");
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goto cleanup;
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}
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/* write something to the file, so a file-backed THP can be allocated */
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num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1);
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close(fd);
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if (num_written < 1) {
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printf("Fail to write data to testing file\n");
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goto cleanup;
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}
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/* split the file-backed THP */
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write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end);
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status = unlink(testfile);
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if (status)
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perror("Cannot remove testing file\n");
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cleanup:
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status = umount(tmpfs_loc);
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if (status) {
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printf("Unable to umount %s\n", tmpfs_loc);
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exit(EXIT_FAILURE);
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}
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status = rmdir(tmpfs_loc);
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if (status) {
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perror("cannot remove tmp dir");
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exit(EXIT_FAILURE);
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}
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printf("file-backed THP split test done, please check dmesg for more information\n");
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}
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int main(int argc, char **argv)
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{
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if (geteuid() != 0) {
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printf("Please run the benchmark as root\n");
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exit(EXIT_FAILURE);
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}
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pagesize = getpagesize();
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pageshift = ffs(pagesize) - 1;
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pmd_pagesize = read_pmd_pagesize();
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split_pmd_thp();
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split_pte_mapped_thp();
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split_file_backed_thp();
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return 0;
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}
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