On 8/9/25 12:31 AM, Zi Yan wrote:
Instead of just checking the existence of PMD folios before and after folio
split tests, use check_folio_orders() to check after-split folio orders.

The following tests are not changed:
1. split_pte_mapped_thp: the test already uses kpageflags to check;
2. split_file_backed_thp: no vaddr available.

Signed-off-by: Zi Yan <[email protected]>
---
  .../selftests/mm/split_huge_page_test.c       | 98 ++++++++++++++-----
  1 file changed, 72 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c 
b/tools/testing/selftests/mm/split_huge_page_test.c
index 5ab488fab1cd..161108717f1c 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -25,6 +25,10 @@
  uint64_t pagesize;
  unsigned int pageshift;
  uint64_t pmd_pagesize;
+unsigned int pmd_order;
+unsigned int max_order;
+
+#define NR_ORDERS (max_order + 1)
#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
  #define SMAP_PATH "/proc/self/smaps"
@@ -36,6 +40,11 @@ uint64_t pmd_pagesize;
#define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages)) +const char *pagemap_proc = "/proc/self/pagemap";
+const char *kpageflags_proc = "/proc/kpageflags";
+int pagemap_fd;
+int kpageflags_fd;
+
  int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
  {
        uint64_t paddr;
@@ -151,6 +160,11 @@ void split_pmd_thp_to_order(int order)
        char *one_page;
        size_t len = 4 * pmd_pagesize;
        size_t i;
+       int *orders;
+
+       orders = (int *)malloc(sizeof(int) * NR_ORDERS);
+       if (!orders)
+               ksft_exit_fail_msg("Fail to allocate memory: %s\n", 
strerror(errno));
one_page = memalign(pmd_pagesize, len);
        if (!one_page)
@@ -172,12 +186,20 @@ void split_pmd_thp_to_order(int order)
                if (one_page[i] != (char)i)
                        ksft_exit_fail_msg("%ld byte corrupted\n", i);
+ memset(orders, 0, sizeof(int) * NR_ORDERS);
+       /* set expected orders */
+       orders[order] = 4 << (pmd_order - order);
+
+       if (check_folio_orders(one_page, len, pagemap_fd, kpageflags_fd,
+                              orders, NR_ORDERS))
+               ksft_exit_fail_msg("Unexpected THP split\n");
if (!check_huge_anon(one_page, 0, pmd_pagesize))
                ksft_exit_fail_msg("Still AnonHugePages not split\n");
ksft_test_result_pass("Split huge pages to order %d successful\n", order);
        free(one_page);
+       free(orders);
  }
void split_pte_mapped_thp(void)
@@ -186,22 +208,6 @@ void split_pte_mapped_thp(void)
        size_t len = 4 * pmd_pagesize;
        uint64_t thp_size;
        size_t i;
-       const char *pagemap_template = "/proc/%d/pagemap";
-       const char *kpageflags_proc = "/proc/kpageflags";
-       char pagemap_proc[255];
-       int pagemap_fd;
-       int kpageflags_fd;
-
-       if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0)
-               ksft_exit_fail_msg("get pagemap proc error: %s\n", 
strerror(errno));
-
-       pagemap_fd = open(pagemap_proc, O_RDONLY);
-       if (pagemap_fd == -1)
-               ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
-
-       kpageflags_fd = open(kpageflags_proc, O_RDONLY);
-       if (kpageflags_fd == -1)
-               ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
                        MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
@@ -259,8 +265,6 @@ void split_pte_mapped_thp(void)
ksft_test_result_pass("Split PTE-mapped huge pages successful\n");
        munmap(one_page, len);
-       close(pagemap_fd);
-       close(kpageflags_fd);
  }
void split_file_backed_thp(int order)
@@ -463,10 +467,16 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, 
const char *fs_loc,
                int order, int offset)
  {
        int fd;
+       char *split_addr;
        char *addr;
        size_t i;
        char testfile[INPUT_MAX];
        int err = 0;
+       int *orders;
+
+       orders = (int *)malloc(sizeof(int) * NR_ORDERS);
+       if (!orders)
+               ksft_exit_fail_msg("Fail to allocate memory: %s\n", 
strerror(errno));
err = snprintf(testfile, INPUT_MAX, "%s/test", fs_loc); @@ -474,16 +484,32 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
                ksft_exit_fail_msg("cannot generate right test file name\n");
err = create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr);
-       if (err)
+       if (err) {
+               free(orders);
                return;
+       }
        err = 0;
- if (offset == -1)
-               write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
-                             (uint64_t)addr + fd_size, order);
-       else
-               write_debugfs(PID_FMT_OFFSET, getpid(), (uint64_t)addr,
-                             (uint64_t)addr + fd_size, order, offset);
+       memset(orders, 0, sizeof(int) * NR_ORDERS);
+       if (offset == -1) {
+               for (split_addr = addr; split_addr < addr + fd_size; split_addr 
+= pmd_pagesize)
+                       write_debugfs(PID_FMT, getpid(), (uint64_t)split_addr,
+                                     (uint64_t)split_addr + pagesize, order);
+
+               /* set expected orders */
+               orders[order] = fd_size / (pagesize << order);
+       } else {
+               int times = fd_size / pmd_pagesize;
+
+               for (split_addr = addr; split_addr < addr + fd_size; split_addr 
+= pmd_pagesize)
+                       write_debugfs(PID_FMT_OFFSET, getpid(), 
(uint64_t)split_addr,
+                                     (uint64_t)split_addr + pagesize, order, 
offset);
+
+               /* set expected orders */
+               for (i = order + 1; i < pmd_order; i++)
+                       orders[i] = times;
+               orders[order] = 2 * times;
+       }
for (i = 0; i < fd_size; i++)
                if (*(addr + i) != (char)i) {
@@ -492,6 +518,14 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, 
const char *fs_loc,
                        goto out;
                }
+ if (check_folio_orders(addr, fd_size, pagemap_fd, kpageflags_fd, orders,
+                              NR_ORDERS)) {
+               ksft_print_msg("Unexpected THP split\n");
+               err = 1;
+               goto out;
+       }
+
+
        if (!check_huge_file(addr, 0, pmd_pagesize)) {
                ksft_print_msg("Still FilePmdMapped not split\n");
                err = EXIT_FAILURE;
@@ -499,6 +533,7 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, 
const char *fs_loc,
        }
out:
+       free(orders);
        munmap(addr, fd_size);
        close(fd);
        unlink(testfile);
@@ -522,7 +557,6 @@ int main(int argc, char **argv)
        const char *fs_loc;
        bool created_tmp;
        int offset;
-       unsigned int max_order;
        unsigned int nr_pages;
        unsigned int tests;
@@ -539,6 +573,7 @@ int main(int argc, char **argv)
        pagesize = getpagesize();
        pageshift = ffs(pagesize) - 1;
        pmd_pagesize = read_pmd_pagesize();
+       pmd_order = GET_ORDER(pmd_pagesize / pagesize);


I think max_order is also same as pmd_order

  nr_pages = pmd_pagesize / pagesize;
  max_order = GET_ORDER(nr_pages);

Can we use one?

        if (!pmd_pagesize)
                ksft_exit_fail_msg("Reading PMD pagesize failed\n");
@@ -547,6 +582,14 @@ int main(int argc, char **argv)
        tests = 2 + (max_order - 1) + (2 * max_order) + (max_order - 1) * 4 + 2;
        ksft_set_plan(tests);
+ pagemap_fd = open(pagemap_proc, O_RDONLY);
+       if (pagemap_fd == -1)
+               ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
+
+       kpageflags_fd = open(kpageflags_proc, O_RDONLY);
+       if (kpageflags_fd == -1)
+               ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
+
        fd_size = 2 * pmd_pagesize;
split_pmd_zero_pages();
@@ -571,6 +614,9 @@ int main(int argc, char **argv)
                        split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, 
offset);
        cleanup_thp_fs(fs_loc, created_tmp);
+ close(pagemap_fd);
+       close(kpageflags_fd);
+
        ksft_finished();
return 0;

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