mm: huge_memory: debugfs for file-backed THP split
Further extend <debugfs>/split_huge_pages to accept "<path>,<pgoff_start>,<pgoff_end>" for file-backed THP split tests since tmpfs may have file backed by THP that mapped nowhere. Update selftest program to test file-backed THP split too. Link: https://lkml.kernel.org/r/20210331235309.332292-2-zi.yan@sent.com Signed-off-by: Zi Yan <ziy@nvidia.com> Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Mika Penttila <mika.penttila@nextfour.com> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Zi Yan
Linus Torvalds
Родитель
fa6c02315f
Коммит
fbe37501b2
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@ -3050,6 +3050,65 @@ out:
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return ret;
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}
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static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
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pgoff_t off_end)
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{
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struct filename *file;
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struct file *candidate;
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struct address_space *mapping;
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int ret = -EINVAL;
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pgoff_t index;
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int nr_pages = 1;
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unsigned long total = 0, split = 0;
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file = getname_kernel(file_path);
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if (IS_ERR(file))
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return ret;
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candidate = file_open_name(file, O_RDONLY, 0);
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if (IS_ERR(candidate))
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goto out;
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pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
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file_path, off_start, off_end);
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mapping = candidate->f_mapping;
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for (index = off_start; index < off_end; index += nr_pages) {
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struct page *fpage = pagecache_get_page(mapping, index,
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FGP_ENTRY | FGP_HEAD, 0);
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nr_pages = 1;
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if (xa_is_value(fpage) || !fpage)
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continue;
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if (!is_transparent_hugepage(fpage))
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goto next;
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total++;
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nr_pages = thp_nr_pages(fpage);
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if (!trylock_page(fpage))
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goto next;
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if (!split_huge_page(fpage))
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split++;
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unlock_page(fpage);
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next:
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put_page(fpage);
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cond_resched();
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}
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filp_close(candidate, NULL);
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ret = 0;
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pr_debug("%lu of %lu file-backed THP split\n", split, total);
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out:
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putname(file);
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return ret;
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}
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#define MAX_INPUT_BUF_SZ 255
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static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
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@ -3057,7 +3116,8 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
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{
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static DEFINE_MUTEX(split_debug_mutex);
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ssize_t ret;
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char input_buf[MAX_INPUT_BUF_SZ]; /* hold pid, start_vaddr, end_vaddr */
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/* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
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char input_buf[MAX_INPUT_BUF_SZ];
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int pid;
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unsigned long vaddr_start, vaddr_end;
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@ -3072,6 +3132,34 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
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goto out;
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input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
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if (input_buf[0] == '/') {
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char *tok;
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char *buf = input_buf;
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char file_path[MAX_INPUT_BUF_SZ];
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pgoff_t off_start = 0, off_end = 0;
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size_t input_len = strlen(input_buf);
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tok = strsep(&buf, ",");
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if (tok) {
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strncpy(file_path, tok, MAX_INPUT_BUF_SZ);
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} else {
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ret = -EINVAL;
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goto out;
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}
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ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
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if (ret != 2) {
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ret = -EINVAL;
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goto out;
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}
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ret = split_huge_pages_in_file(file_path, off_start, off_end);
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if (!ret)
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ret = input_len;
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goto out;
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}
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ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
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if (ret == 1 && pid == 1) {
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split_huge_pages_all();
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@ -7,11 +7,13 @@
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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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@ -24,6 +26,9 @@ uint64_t pmd_pagesize;
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#define SMAP_PATH "/proc/self/smaps"
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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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@ -87,13 +92,16 @@ static int write_file(const char *path, const char *buf, size_t buflen)
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return (unsigned int) numwritten;
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}
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static void write_debugfs(int pid, uint64_t vaddr_start, uint64_t vaddr_end)
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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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ret = snprintf(input, INPUT_MAX, "%d,0x%lx,0x%lx", pid, vaddr_start,
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vaddr_end);
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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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@ -183,7 +191,8 @@ void split_pmd_thp(void)
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}
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/* split all THPs */
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write_debugfs(getpid(), (uint64_t)one_page, (uint64_t)one_page + len);
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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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@ -274,7 +283,7 @@ void split_pte_mapped_thp(void)
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}
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/* split all remapped THPs */
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write_debugfs(getpid(), (uint64_t)pte_mapped,
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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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@ -300,6 +309,68 @@ void split_pte_mapped_thp(void)
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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, sizeof(tmpfs_loc));
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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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@ -313,6 +384,7 @@ int main(int argc, char **argv)
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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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