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To: Zi Yan Cc: Linux MM , Linux Kernel Mailing List , linux-kselftest@vger.kernel.org, "Kirill A . Shutemov" , Andrew Morton , Shuah Khan , John Hubbard , Sandipan Das , David Hildenbrand , Mika Penttila Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 9owebtr3sfusx7myayhzzs54fbuf91pc X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: CF8A7C0001FE Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf06; identity=mailfrom; envelope-from=""; helo=mail-ed1-f47.google.com; client-ip=209.85.208.47 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615936742-493306 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 15, 2021 at 1:34 PM Zi Yan wrote: > > From: Zi Yan > > Further extend /split_huge_pages to accept > ",," 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 > Signed-off-by: Zi Yan > --- > mm/huge_memory.c | 95 ++++++++++++++++++- > .../selftests/vm/split_huge_page_test.c | 79 ++++++++++++++- > 2 files changed, 166 insertions(+), 8 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 3bfee54e2cd0..da91ee97d944 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3043,12 +3043,72 @@ 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 off_cur; > + 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_info("split file-backed THPs in file: %s, offset: [0x%lx - 0x%lx]\n", > + file_path, off_start, off_end); > + > + mapping = candidate->f_mapping; > + > + for (off_cur = off_start; off_cur < off_end;) { > + struct page *fpage = pagecache_get_page(mapping, off_cur, > + FGP_ENTRY | FGP_HEAD, 0); > + > + if (xa_is_value(fpage) || !fpage) { Why do you have FGP_ENTRY? It seems it would return page instead of NULL if page is value. So I think you could remove FGP_ENTRY and xa_is_value() check as well. > + off_cur += PAGE_SIZE; > + continue; > + } > + > + if (!is_transparent_hugepage(fpage)) { > + off_cur += PAGE_SIZE; > + goto next; > + } > + total++; > + off_cur = fpage->index + thp_size(fpage); > + > + if (!trylock_page(fpage)) > + goto next; > + > + if (!split_huge_page(fpage)) > + split++; > + > + unlock_page(fpage); > +next: > + put_page(fpage); > + } > + > + filp_close(candidate, NULL); > + ret = 0; > + > + pr_info("%lu of %lu file-backed THP split\n", split, total); > +out: > + putname(file); > + return ret; > +} > + > static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, > size_t count, loff_t *ppops) > { > static DEFINE_MUTEX(mutex); > ssize_t ret; > - char input_buf[80]; /* hold pid, start_vaddr, end_vaddr */ > + /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ > + char input_buf[MAX_INPUT]; I didn't find where MAX_INPUT is defined in your patch. Just saw include/uapi/linux/limits.h have it defined. Is it the one you really refer to? > int pid; > unsigned long vaddr_start, vaddr_end; > > @@ -3058,11 +3118,40 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, > > ret = -EFAULT; > > - memset(input_buf, 0, 80); > + memset(input_buf, 0, MAX_INPUT); > if (copy_from_user(input_buf, buf, min_t(size_t, count, 80))) > goto out; > > - input_buf[79] = '\0'; > + input_buf[MAX_INPUT - 1] = '\0'; > + > + if (input_buf[0] == '/') { > + char *tok; > + char *buf = input_buf; > + char file_path[MAX_INPUT]; > + 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); > + } else { > + ret = -EINVAL; > + goto out; > + } > + > + ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); > + if (ret != 2) { > + pr_info("ret: %ld\n", ret); > + 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 9f33ddbb3182..0202702f7eda 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 > #include > +#include > #include > #include > #include > #include > #include > +#include > #include > #include > > @@ -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); > @@ -178,7 +186,8 @@ 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) { > @@ -269,7 +278,7 @@ 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 */ > @@ -295,6 +304,65 @@ 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]; > + > + 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, 0, 1024); > + > + 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) { > @@ -308,6 +376,7 @@ int main(int argc, char **argv) > > split_pmd_thp(); > split_pte_mapped_thp(); > + split_file_backed_thp(); > > return 0; > } > -- > 2.30.1 >