[PATCH v9 8/8] selftests/mm: add tests for folio_split(), buddy allocator like split

Zi Yan
2025-02-26T21:01:10Z

It splits page cache folios to orders from 0 to 8 at different in-folio
offset.

Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Kairui Song <kasong@tencent.com>
---
.../selftests/mm/split_huge_page_test.c | 34 +++++++++++++++----
1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index e0304046b1a0..719c5e2a6624 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -14,6 +14,7 @@
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/mount.h>
+#include <sys/param.h>
#include <malloc.h>
#include <stdbool.h>
#include <time.h>
@@ -456,7 +457,8 @@ int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd,
return -1;
}

-void split_thp_in_pagecache_to_order(size_t fd_size, int order, const char *fs_loc)
+void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
+ int order, int offset)
{
int fd;
char *addr;
@@ -474,7 +476,12 @@ void split_thp_in_pagecache_to_order(size_t fd_size, int order, const char *fs_l
return;
err = 0;

- write_debugfs(PID_FMT, getpid(), (uint64_t)addr, (uint64_t)addr + fd_size, order);
+ if (offset == -1)
+ write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
+ (uint64_t)addr + fd_size, order);
+ else
+ write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
+ (uint64_t)addr + fd_size, order, offset);

for (i = 0; i < fd_size; i++)
if (*(addr + i) != (char)i) {
@@ -493,9 +500,15 @@ void split_thp_in_pagecache_to_order(size_t fd_size, int order, const char *fs_l
munmap(addr, fd_size);
close(fd);
unlink(testfile);
- if (err)
- ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d failed\n", order);
- ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d passed\n", order);
+ if (offset == -1) {
+ if (err)
+ ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d failed\n", order);
+ ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d passed\n", order);
+ } else {
+ if (err)
+ ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d at in-folio offset %d failed\n", order, offset);
+ ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d at in-folio offset %d passed\n", order, offset);
+ }
}

int main(int argc, char **argv)
@@ -506,6 +519,7 @@ int main(int argc, char **argv)
char fs_loc_template[] = "/tmp/thp_fs_XXXXXX";
const char *fs_loc;
bool created_tmp;
+ int offset;

ksft_print_header();

@@ -517,7 +531,7 @@ int main(int argc, char **argv)
if (argc > 1)
optional_xfs_path = argv[1];

- ksft_set_plan(1+8+1+9+9);
+ ksft_set_plan(1+8+1+9+9+8*4+2);

pagesize = getpagesize();
pageshift = ffs(pagesize) - 1;
@@ -540,7 +554,13 @@ int main(int argc, char **argv)
created_tmp = prepare_thp_fs(optional_xfs_path, fs_loc_template,
&fs_loc);
for (i = 8; i >= 0; i--)
- split_thp_in_pagecache_to_order(fd_size, i, fs_loc);
+ split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, -1);
+
+ for (i = 0; i < 9; i++)
+ for (offset = 0;
+ offset < pmd_pagesize / pagesize;
+ offset += MAX(pmd_pagesize / pagesize / 4, 1 << i))
+ split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, offset);
cleanup_thp_fs(fs_loc, created_tmp);

ksft_finished();
--
2.47.2