The patch titled
Subject: selftests/mm: make file-backed THP split work by writing PMD size data
has been added to the -mm mm-unstable branch. Its filename is
selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Zi Yan <ziy@xxxxxxxxxx>
Subject: selftests/mm: make file-backed THP split work by writing PMD size data
Date: Wed, 22 Jan 2025 11:19:26 -0500
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.
Link: https://lkml.kernel.org/r/20250122161928.1240637-1-ziy@xxxxxxxxxx
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickens <hughd@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Kirill A. Shuemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: linmiaohe <linmiaohe@xxxxxxxxxx>
Cc: Mattew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/mm/split_huge_page_test.c | 52 ++++++++++--
1 file changed, 44 insertions(+), 8 deletions(-)
--- a/tools/testing/selftests/mm/split_huge_page_test.c~selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data
+++ a/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");
}
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch
mm-huge_memory-allow-split-shmem-large-folio-to-any-lower-order.patch
selftests-mm-test-splitting-file-backed-thp-to-any-lower-order.patch
