Re: [PATCH v4 08/15] selftest/mm: align memory size to huge page size in hugepage-mremap test

Sayali Patil
2026-04-08T14:31:09Z

On 07/04/26 20:27, Zi Yan wrote:
> On 6 Apr 2026, at 5:19, Sayali Patil wrote:
>
>> 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")
>> 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
>
> LGTM. BTW, it seems that multiple files, pkey-helpers.h, migration.c,
> uffed-unit-test.c, hmm-tests.c, have their own ALIGN or ALIGN_UP.
> They can be moved to vm_utils.h, later if someone wants to do a cleanup.
>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
>
> Best Regards,
> Yan, Zi
>
Yes, I noticed that as well. I am planning to clean that up separately
later.

Thanks,
Sayali