On 22/01/2026 5:02 pm, Kevin Brodsky wrote:
Many cow tests rely on FORCE_READ() to populate pages. Introduce a
helper to make sure that the pages are actually populated, and fail
otherwise.
Suggested-by: David Hildenbrand (Red Hat) <[email protected]>
Signed-off-by: Kevin Brodsky <[email protected]>
---
tools/testing/selftests/mm/cow.c | 43 ++++++++++++++++++++++++--------
1 file changed, 33 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 83b3563be26b..d9c69c04b67d 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -75,6 +75,18 @@ static bool range_is_swapped(void *addr, size_t size)
return true;
}
+static bool populate_page_checked(char *addr)
+{
+ bool ret;
+
+ FORCE_READ(*addr);
+ ret = pagemap_is_populated(pagemap_fd, addr);
Very useful. Maybe extending FORCE_READ can help the entire suite?
+ if (!ret)
+ ksft_print_msg("Failed to populate page\n");
+
+ return ret;
+}
+
struct comm_pipes {
int child_ready[2];
int parent_ready[2];
@@ -1549,8 +1561,10 @@ static void run_with_zeropage(non_anon_test_fn fn, const
char *desc)
}
/* Read from the page to populate the shared zeropage. */
- FORCE_READ(*mem);
- FORCE_READ(*smem);
+ if (!populate_page_checked(mem) || !populate_page_checked(smem)) {
+ log_test_result(KSFT_FAIL);
+ goto munmap;
+ }
fn(mem, smem, pagesize);
munmap:
@@ -1612,8 +1626,11 @@ static void run_with_huge_zeropage(non_anon_test_fn fn,
const char *desc)
* the first sub-page and test if we get another sub-page populated
* automatically.
*/
- FORCE_READ(*mem);
- FORCE_READ(*smem);
+ if (!populate_page_checked(mem) || !populate_page_checked(smem)) {
+ log_test_result(KSFT_FAIL);
+ goto munmap;
+ }
+
if (!pagemap_is_populated(pagemap_fd, mem + pagesize) ||
!pagemap_is_populated(pagemap_fd, smem + pagesize)) {
ksft_test_result_skip("Did not get THPs populated\n");
@@ -1663,8 +1680,10 @@ static void run_with_memfd(non_anon_test_fn fn, const
char *desc)
}
/* Fault the page in. */
- FORCE_READ(*mem);
- FORCE_READ(*smem);
+ if (!populate_page_checked(mem) || !populate_page_checked(smem)) {
+ log_test_result(KSFT_FAIL);
+ goto munmap;
+ }
fn(mem, smem, pagesize);
munmap:
@@ -1719,8 +1738,10 @@ static void run_with_tmpfile(non_anon_test_fn fn, const
char *desc)
}
/* Fault the page in. */
- FORCE_READ(*mem);
- FORCE_READ(*smem);
+ if (!populate_page_checked(mem) || !populate_page_checked(smem)) {
+ log_test_result(KSFT_FAIL);
+ goto munmap;
+ }
fn(mem, smem, pagesize);
munmap:
@@ -1773,8 +1794,10 @@ static void run_with_memfd_hugetlb(non_anon_test_fn fn,
const char *desc,
}
/* Fault the page in. */
- FORCE_READ(*mem);
- FORCE_READ(*smem);
+ if (!populate_page_checked(mem) || !populate_page_checked(smem)) {
+ log_test_result(KSFT_FAIL);
+ goto munmap;
+ }
fn(mem, smem, hugetlbsize);
munmap:
