Commit acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs") changes huge=always to allocate THP/mTHP based on write size and split_huge_page_test does not write PMD size data, so file-back THP is not created during the test. Fix it by writing PMD size data.

Signed-off-by: Zi Yan ziy@nvidia.com --- V1 -> V2: write PMD size data instead of setting /sys/kernel/mm/transparent_hugepage/shmem_enabled to "force".

.../selftests/mm/split_huge_page_test.c | 52 ++++++++++++++++--- 1 file changed, 44 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 3f353f3d070f..ba498aaaf857 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -265,14 +265,28 @@ 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]; + ssize_t num_written, num_read; + char *file_buf1, *file_buf2; uint64_t pgoff_start = 0, pgoff_end = 1024; + int i;

ksft_print_msg("Please enable pr_debug in split_huge_pages_in_file() for more info.\n");

+ file_buf1 = (char *)malloc(pmd_pagesize); + file_buf2 = (char *)malloc(pmd_pagesize); + + if (!file_buf1 || !file_buf2) { + ksft_print_msg("cannot allocate file buffers\n"); + goto out; + } + + for (i = 0; i < pmd_pagesize; i++) + file_buf1[i] = (char)i; + memset(file_buf2, 0, pmd_pagesize); + status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");

if (status) @@ -281,26 +295,45 @@ void split_file_backed_thp(void) status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc); if (status >= INPUT_MAX) { ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n"); + goto cleanup; }

- fd = open(testfile, O_CREAT|O_WRONLY, 0664); + fd = open(testfile, O_CREAT|O_RDWR, 0664); if (fd == -1) { ksft_perror("Cannot open testing file"); goto cleanup; }

- /* write something to the file, so a file-backed THP can be allocated */ - num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1); - close(fd); + /* write pmd size data to the file, so a file-backed THP can be allocated */ + num_written = write(fd, file_buf1, pmd_pagesize);

- if (num_written < 1) { - ksft_perror("Fail to write data to testing file"); - goto cleanup; + if (num_written == -1 || num_written != pmd_pagesize) { + ksft_perror("Failed to write data to testing file"); + goto close_file; }

/* split the file-backed THP */ write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, 0);

+ /* check file content after split */ + status = lseek(fd, 0, SEEK_SET); + if (status == -1) { + ksft_perror("Cannot lseek file"); + goto close_file; + } + + num_read = read(fd, file_buf2, num_written); + if (num_read == -1 || num_read != num_written) { + ksft_perror("Cannot read file content back"); + goto close_file; + } + + if (strncmp(file_buf1, file_buf2, pmd_pagesize) != 0) { + ksft_print_msg("File content changed\n"); + goto close_file; + } + + close(fd); status = unlink(testfile); if (status) { ksft_perror("Cannot remove testing file"); @@ -321,9 +354,12 @@ void split_file_backed_thp(void) ksft_test_result_pass("File-backed THP split test done\n"); return;

+close_file: + close(fd); cleanup: umount(tmpfs_loc); rmdir(tmpfs_loc); +out: ksft_exit_fail_msg("Error occurred\n"); }