From: Zi Yan ziy@nvidia.com
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.
Suggested-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Signed-off-by: Zi Yan ziy@nvidia.com Reviewed-by: Yang Shi shy828301@gmail.com --- mm/huge_memory.c | 90 ++++++++++++++++++- .../selftests/vm/split_huge_page_test.c | 82 +++++++++++++++-- 2 files changed, 166 insertions(+), 6 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1bcab247aea8..eb0f3aaf49f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3062,6 +3062,65 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, return ret; }
+static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, + pgoff_t off_end) +{ + struct filename *file; + struct file *candidate; + struct address_space *mapping; + int ret = -EINVAL; + pgoff_t index; + int nr_pages = 1; + unsigned long total = 0, split = 0; + + file = getname_kernel(file_path); + if (IS_ERR(file)) + return ret; + + candidate = file_open_name(file, O_RDONLY, 0); + if (IS_ERR(candidate)) + goto out; + + pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", + file_path, off_start, off_end); + + mapping = candidate->f_mapping; + + for (index = off_start; index < off_end; index += nr_pages) { + struct page *fpage = pagecache_get_page(mapping, index, + FGP_ENTRY | FGP_HEAD, 0); + + nr_pages = 1; + if (xa_is_value(fpage) || !fpage) + continue; + + if (!is_transparent_hugepage(fpage)) + goto next; + + total++; + nr_pages = thp_nr_pages(fpage); + + if (!trylock_page(fpage)) + goto next; + + if (!split_huge_page(fpage)) + split++; + + unlock_page(fpage); +next: + put_page(fpage); + cond_resched(); + } + + filp_close(candidate, NULL); + ret = 0; + + pr_debug("%lu of %lu file-backed THP split\n", split, total); +out: + putname(file); + return ret; +} + #define MAX_INPUT_BUF_SZ 255
static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, @@ -3069,7 +3128,8 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, { static DEFINE_MUTEX(split_debug_mutex); ssize_t ret; - char input_buf[MAX_INPUT_BUF_SZ]; /* hold pid, start_vaddr, end_vaddr */ + /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ + char input_buf[MAX_INPUT_BUF_SZ]; int pid; unsigned long vaddr_start, vaddr_end;
@@ -3084,6 +3144,34 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, goto out;
input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; + + if (input_buf[0] == '/') { + char *tok; + char *buf = input_buf; + char file_path[MAX_INPUT_BUF_SZ]; + pgoff_t off_start = 0, off_end = 0; + size_t input_len = strlen(input_buf); + + tok = strsep(&buf, ","); + if (tok) { + strncpy(file_path, tok, MAX_INPUT_BUF_SZ); + } else { + ret = -EINVAL; + goto out; + } + + ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); + if (ret != 2) { + ret = -EINVAL; + goto out; + } + ret = split_huge_pages_in_file(file_path, off_start, off_end); + if (!ret) + ret = input_len; + + goto out; + } + ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); if (ret == 1 && pid == 1) { split_huge_pages_all(); diff --git a/tools/testing/selftests/vm/split_huge_page_test.c b/tools/testing/selftests/vm/split_huge_page_test.c index 2c0c18e60c57..1af16d2c2a0a 100644 --- a/tools/testing/selftests/vm/split_huge_page_test.c +++ b/tools/testing/selftests/vm/split_huge_page_test.c @@ -7,11 +7,13 @@ #define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> +#include <stdarg.h> #include <unistd.h> #include <inttypes.h> #include <string.h> #include <fcntl.h> #include <sys/mman.h> +#include <sys/mount.h> #include <malloc.h> #include <stdbool.h>
@@ -24,6 +26,9 @@ uint64_t pmd_pagesize; #define SMAP_PATH "/proc/self/smaps" #define INPUT_MAX 80
+#define PID_FMT "%d,0x%lx,0x%lx" +#define PATH_FMT "%s,0x%lx,0x%lx" + #define PFN_MASK ((1UL<<55)-1) #define KPF_THP (1UL<<22)
@@ -87,13 +92,16 @@ static int write_file(const char *path, const char *buf, size_t buflen) return (unsigned int) numwritten; }
-static void write_debugfs(int pid, uint64_t vaddr_start, uint64_t vaddr_end) +static void write_debugfs(const char *fmt, ...) { char input[INPUT_MAX]; int ret; + va_list argp; + + va_start(argp, fmt); + ret = vsnprintf(input, INPUT_MAX, fmt, argp); + va_end(argp);
- ret = snprintf(input, INPUT_MAX, "%d,0x%lx,0x%lx", pid, vaddr_start, - vaddr_end); if (ret >= INPUT_MAX) { printf("%s: Debugfs input is too long\n", __func__); exit(EXIT_FAILURE); @@ -183,7 +191,8 @@ void split_pmd_thp(void) }
/* split all THPs */ - write_debugfs(getpid(), (uint64_t)one_page, (uint64_t)one_page + len); + write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, + (uint64_t)one_page + len);
for (i = 0; i < len; i++) if (one_page[i] != (char)i) { @@ -274,7 +283,7 @@ void split_pte_mapped_thp(void) }
/* split all remapped THPs */ - write_debugfs(getpid(), (uint64_t)pte_mapped, + write_debugfs(PID_FMT, getpid(), (uint64_t)pte_mapped, (uint64_t)pte_mapped + pagesize * 4);
/* smap does not show THPs after mremap, use kpageflags instead */ @@ -300,6 +309,68 @@ void split_pte_mapped_thp(void) close(kpageflags_fd); }
+void split_file_backed_thp(void) +{ + int status; + int fd; + ssize_t num_written; + char tmpfs_template[] = "/tmp/thp_split_XXXXXX"; + const char *tmpfs_loc = mkdtemp(tmpfs_template); + char testfile[INPUT_MAX]; + uint64_t pgoff_start = 0, pgoff_end = 1024; + + printf("Please enable pr_debug in split_huge_pages_in_file() if you need more info.\n"); + + status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m"); + + if (status) { + printf("Unable to create a tmpfs for testing\n"); + exit(EXIT_FAILURE); + } + + status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc); + if (status >= INPUT_MAX) { + printf("Fail to create file-backed THP split testing file\n"); + goto cleanup; + } + + fd = open(testfile, O_CREAT|O_WRONLY); + if (fd == -1) { + perror("Cannot open testing file\n"); + goto cleanup; + } + + /* write something to the file, so a file-backed THP can be allocated */ + num_written = write(fd, tmpfs_loc, sizeof(tmpfs_loc)); + close(fd); + + if (num_written < 1) { + printf("Fail to write data to testing file\n"); + goto cleanup; + } + + /* split the file-backed THP */ + write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end); + + status = unlink(testfile); + if (status) + perror("Cannot remove testing file\n"); + +cleanup: + status = umount(tmpfs_loc); + if (status) { + printf("Unable to umount %s\n", tmpfs_loc); + exit(EXIT_FAILURE); + } + status = rmdir(tmpfs_loc); + if (status) { + perror("cannot remove tmp dir"); + exit(EXIT_FAILURE); + } + + printf("file-backed THP split test done, please check dmesg for more information\n"); +} + int main(int argc, char **argv) { if (geteuid() != 0) { @@ -313,6 +384,7 @@ int main(int argc, char **argv)
split_pmd_thp(); split_pte_mapped_thp(); + split_file_backed_thp();
return 0; }