On 9 May 2026, at 3:51, David Hildenbrand (Arm) wrote:

> On 5/6/26 15:11, Zi Yan wrote:
>> On 4 May 2026, at 12:23, Nico Pache wrote:
>>
>>> On 4/29/26 9:35 AM, Zi Yan wrote:
>>>> Change the requirement to a file system with large folio support and the
>>>> supported order needs to include PMD_ORDER.
>>>>
>>>> Also add tests of opening a file with read write permission and populating
>>>> folios with writes. Reuse the XFS image from split_huge_page_test.
>>>>
>>>> Signed-off-by: Zi Yan <[email protected]>
>>>> ---
>>>>   tools/testing/selftests/mm/khugepaged.c   | 131 +++++++++++++++-------
>>>>   tools/testing/selftests/mm/run_vmtests.sh |  12 +-
>>>>   2 files changed, 102 insertions(+), 41 deletions(-)
>>>>
>>>> diff --git a/tools/testing/selftests/mm/khugepaged.c 
>>>> b/tools/testing/selftests/mm/khugepaged.c
>>>> index a6bb9d50363d2..80b913185c643 100644
>>>> --- a/tools/testing/selftests/mm/khugepaged.c
>>>> +++ b/tools/testing/selftests/mm/khugepaged.c
>>>> @@ -49,7 +49,8 @@ struct mem_ops {
>>>>    const char *name;
>>>>   };
>>>>  -static struct mem_ops *file_ops;
>>>> +static struct mem_ops *read_only_file_ops;
>>>> +static struct mem_ops *read_write_file_ops;
>>>>   static struct mem_ops *anon_ops;
>>>>   static struct mem_ops *shmem_ops;
>>>>  @@ -112,7 +113,8 @@ static void restore_settings(int sig)
>>>>   static void save_settings(void)
>>>>   {
>>>>    printf("Save THP and khugepaged settings...");
>>>> -  if (file_ops && finfo.type == VMA_FILE)
>>>> +  if ((read_only_file_ops || read_write_file_ops) &&
>>>> +      finfo.type == VMA_FILE)
>>>>            thp_set_read_ahead_path(finfo.dev_queue_read_ahead_path);
>>>>    thp_save_settings();
>>>>  @@ -364,11 +366,14 @@ static bool anon_check_huge(void *addr, int 
>>>> nr_hpages)
>>>>    return check_huge_anon(addr, nr_hpages, hpage_pmd_size);
>>>>   }
>>>>  -static void *file_setup_area(int nr_hpages)
>>>> +static void *file_setup_area_common(int nr_hpages, bool read_only)
>>>>   {
>>>>    int fd;
>>>>    void *p;
>>>>    unsigned long size;
>>>> +  int open_opt = read_only ? O_RDONLY : O_RDWR;
>>>> +  int mmap_prot = read_only ? PROT_READ : (PROT_READ | PROT_WRITE);
>>>> +  int mmap_opt = read_only ? MAP_PRIVATE : MAP_SHARED;
>>>>            unlink(finfo.path);  /* Cleanup from previous failed tests */
>>>>    printf("Creating %s for collapse%s...", finfo.path,
>>>> @@ -399,14 +404,15 @@ static void *file_setup_area(int nr_hpages)
>>>>    munmap(p, size);
>>>>    success("OK");
>>>>  - printf("Opening %s read only for collapse...", finfo.path);
>>>> -  finfo.fd = open(finfo.path, O_RDONLY, 777);
>>>> +  printf("Opening %s %s for collapse...", finfo.path,
>>>> +         read_only ? "read only" : "read-write");
>>>> +  finfo.fd = open(finfo.path, open_opt, 777);
>>>>    if (finfo.fd < 0) {
>>>>            perror("open()");
>>>>            exit(EXIT_FAILURE);
>>>>    }
>>>> -  p = mmap(BASE_ADDR, size, PROT_READ,
>>>> -           MAP_PRIVATE, finfo.fd, 0);
>>>> +  p = mmap(BASE_ADDR, size, mmap_prot,
>>>> +           mmap_opt, finfo.fd, 0);
>>>>    if (p == MAP_FAILED || p != BASE_ADDR) {
>>>>            perror("mmap()");
>>>>            exit(EXIT_FAILURE);
>>>> @@ -418,6 +424,16 @@ static void *file_setup_area(int nr_hpages)
>>>>    return p;
>>>>   }
>>>>  +static void *file_setup_read_only_area(int nr_hpages)
>>>> +{
>>>> +  return file_setup_area_common(nr_hpages, /* read_only= */ true);
>>>> +}
>>>> +
>>>> +static void *file_setup_read_write_area(int nr_hpages)
>>>> +{
>>>> +  return file_setup_area_common(nr_hpages, /* read_only= */ false);
>>>> +}
>>>> +
>>>>   static void file_cleanup_area(void *p, unsigned long size)
>>>>   {
>>>>    munmap(p, size);
>>>> @@ -425,14 +441,25 @@ static void file_cleanup_area(void *p, unsigned long 
>>>> size)
>>>>    unlink(finfo.path);
>>>>   }
>>>>  -static void file_fault(void *p, unsigned long start, unsigned long end)
>>>> +static void file_fault_common(void *p, unsigned long start, unsigned long 
>>>> end,
>>>> +          int madv_ops)
>>>>   {
>>>> -  if (madvise(((char *)p) + start, end - start, MADV_POPULATE_READ)) {
>>>> +  if (madvise(((char *)p) + start, end - start, madv_ops)) {
>>>>            perror("madvise(MADV_POPULATE_READ");
>>>>            exit(EXIT_FAILURE);
>>>>    }
>>>>   }
>>>>  +static void file_fault_read(void *p, unsigned long start, unsigned long 
>>>> end)
>>>> +{
>>>> +  file_fault_common(p, start, end, MADV_POPULATE_READ);
>>>> +}
>>>> +
>>>> +static void file_fault_write(void *p, unsigned long start, unsigned long 
>>>> end)
>>>> +{
>>>> +  file_fault_common(p, start, end, MADV_POPULATE_WRITE);
>>>> +}
>>>> +
>>>>   static bool file_check_huge(void *addr, int nr_hpages)
>>>>   {
>>>>    switch (finfo.type) {
>>>> @@ -488,10 +515,18 @@ static struct mem_ops __anon_ops = {
>>>>    .name = "anon",
>>>>   };
>>>>  -static struct mem_ops __file_ops = {
>>>> -  .setup_area = &file_setup_area,
>>>> +static struct mem_ops __read_only_file_ops = {
>>>> +  .setup_area = &file_setup_read_only_area,
>>>>    .cleanup_area = &file_cleanup_area,
>>>> -  .fault = &file_fault,
>>>> +  .fault = &file_fault_read,
>>>> +  .check_huge = &file_check_huge,
>>>> +  .name = "file",
>>>> +};
>>>> +
>>>> +static struct mem_ops __read_write_file_ops = {
>>>> +  .setup_area = &file_setup_read_write_area,
>>>> +  .cleanup_area = &file_cleanup_area,
>>>> +  .fault = &file_fault_write,
>>>>    .check_huge = &file_check_huge,
>>>>    .name = "file",
>>>>   };
>>>> @@ -504,6 +539,18 @@ static struct mem_ops __shmem_ops = {
>>>>    .name = "shmem",
>>>>   };
>>>>  +static bool is_tmpfs(struct mem_ops *ops)
>>>> +{
>>>> +  return (ops == &__read_only_file_ops ||
>>>> +          ops == &__read_write_file_ops) &&
>>>> +         finfo.type == VMA_SHMEM;
>>>> +}
>>>> +
>>>> +static bool is_anon(struct mem_ops *ops)
>>>> +{
>>>> +  return ops == &__anon_ops;
>>>> +}
>>>> +
>>>>   static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
>>>>                           struct mem_ops *ops, bool expect)
>>>>   {
>>>> @@ -512,6 +559,10 @@ static void __madvise_collapse(const char *msg, char 
>>>> *p, int nr_hpages,
>>>>            printf("%s...", msg);
>>>>  + /* read&write file collapse always fail */
>>>
>>> Just to confirm, you are adding the write part here so that before commit 
>>> 13 & 14, the behavior is that it will fail. Whereas after with patch 13/14, 
>>> we expect this behavior to be supported correct?
>> Yes.
>
> Confusing, we usually add new test after adding new functionality, not the 
> other
> way around? :)

My intention is to make sure my changes do not alter existing read-only 
collapse behavior
before patch 13.


Best Regards,
Yan, Zi

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