[PATCH v6 08/14] selftest/mm: align memory size to huge page size in hugepage-mremap test

Sayali Patil
2026-05-04T08:25:58Z

The hugepage-mremap selftest uses a default mapping size of 10MB
when no argument is provided. This size is not guaranteed to be
aligned to the system hugepage size, which can cause munmap() to fail
and mremap() to succeed where a failure is expected.

Align the mapping length to the runtime hugepage size using
default_huge_page_size() to ensure the mapping is properly
aligned. Also handle the case where
default_huge_page_size() returns 0 by skipping the test.

Before patch:
running ./hugepage-mremap
------------------------------
TAP version 13
1..1
Map haddr: Returned address is 0x7eaa40000000
Map daddr: Returned address is 0x7daa40000000
Map vaddr: Returned address is 0x7faa40000000
Address returned by mmap() = 0x7fffaa600000
Mremap: Returned address is 0x7faa40000000
First hex is 0
First hex is 3020100
Bail out! mremap: Expected failure, but call succeeded
Planned tests != run tests (1 != 0)
Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
[FAIL]
not ok 1 hugepage-mremap # exit=1

After patch:
running ./hugepage-mremap
-------------------------
TAP version 13
1..1
Map haddr: Returned address is 0x7eaa40000000
Map daddr: Returned address is 0x7daa40000000
Map vaddr: Returned address is 0x7faa40000000
Address returned by mmap() = 0x7fff13000000
Mremap: Returned address is 0x7faa40000000
First hex is 0
First hex is 3020100
ok 1 Read same data
Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
[PASS]
ok 1 hugepage-mremap

Fixes: f77a286de48c ("mm, hugepages: make memory size variable in hugepage-mremap selftest")
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
tools/testing/selftests/mm/hugepage-mremap.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index b8f7d92e5a35..f66e4d806477 100644
--- a/tools/testing/selftests/mm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -32,6 +32,7 @@

#define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
#define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
+#define ALIGN(x, a) (((x) + ((a) - 1)) & ~((a) - 1))

static void check_bytes(char *addr)
{
@@ -110,6 +111,7 @@ int main(int argc, char *argv[])
{
size_t length = 0;
int ret = 0, fd;
+ size_t hpage_size;

ksft_print_header();
ksft_set_plan(1);
@@ -126,6 +128,14 @@ int main(int argc, char *argv[])
length = DEFAULT_LENGTH_MB;

length = MB_TO_BYTES(length);
+
+ hpage_size = default_huge_page_size();
+ if (!hpage_size)
+ ksft_exit_skip("Unable to determine huge page size\n");
+
+ /* Ensure length is hugepage aligned */
+ length = ALIGN(length, hpage_size);
+
fd = memfd_create(argv[0], MFD_HUGETLB);
if (fd < 0)
ksft_exit_fail_msg("Open failed: %s\n", strerror(errno));
--
2.52.0