[Patch v2] selftests/mm: check content to see whether mremap corrupt data

[Wei Yang]

After mremap(), add a check on content to see whether mremap corrupt
data.

Signed-off-by: Wei Yang <richard.weiy...@gmail.com>

---
v2: add check on content instead of just test backed folio
---
 tools/testing/selftests/mm/split_huge_page_test.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c 
b/tools/testing/selftests/mm/split_huge_page_test.c
index 10ae65ea032f..229b6dcabece 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -423,10 +423,14 @@ static void split_pte_mapped_thp(void)
 
        /* smap does not show THPs after mremap, use kpageflags instead */
        thp_size = 0;
-       for (i = 0; i < pagesize * 4; i++)
+       for (i = 0; i < pagesize * 4; i++) {
+               if (pte_mapped[i] != (char)i)
+                       ksft_exit_fail_msg("%ld byte corrupted\n", i);
+
                if (i % pagesize == 0 &&
                    is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, 
kpageflags_fd))
                        thp_size++;
+       }
 
        if (thp_size != 4)
                ksft_exit_fail_msg("Some THPs are missing during mremap\n");
-- 
2.34.1