selftests/mm: add tests for folio_split(), buddy allocator like split

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

Link: https://lkml.kernel.org/r/20250226210032.2044041-9-ziy@nvidia.com
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index e0304046b1a0c888612bf93108c2518544a9159f..719c5e2a66243b677239dd1ed14cab28753d99f7 100644 (file)
--- 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 @@ err_out_unlink:
        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 @@ out:
        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();