[PATCH v7 3/3] kselftest: mm: remove check_huge_shmem()

From: Yeoreum Yun

Date: Mon Sep 21 2026 - 06:44:14 EST


check_huge_shmem() was required to distinguish shmem huge pages because
/proc/self/smaps reports them using a dedicated “ShmemPmdMapped” entry,
as opposed to “FilePmdMapped” for file-backed huge pages.

Now that /proc/self/smaps is no longer used to detect huge pages and
/proc/kpageflags is used instead, it is sufficient to distinguish
between file-backed and anonymous pages since the ShmemPmdMapped is also
kind of file-backed.

Therefore, remove check_huge_shmem() and use check_huge_file() instead
and cleanup khugepaged's check_huge operation in mem_ops.

Suggested-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
---
tools/testing/selftests/mm/folio_split_race_test.c | 2 +-
tools/testing/selftests/mm/khugepaged.c | 38 ++++------------------
tools/testing/selftests/mm/uffd-common.c | 4 +--
tools/testing/selftests/mm/vm_util.c | 5 ---
tools/testing/selftests/mm/vm_util.h | 1 -
5 files changed, 9 insertions(+), 41 deletions(-)

diff --git a/tools/testing/selftests/mm/folio_split_race_test.c b/tools/testing/selftests/mm/folio_split_race_test.c
index 1960635a953eb..4c0d3b6a411b8 100644
--- a/tools/testing/selftests/mm/folio_split_race_test.c
+++ b/tools/testing/selftests/mm/folio_split_race_test.c
@@ -182,7 +182,7 @@ static uint64_t run_iteration(void)
for (i = 0; i < TOTAL_PAGES; i++)
fill_page(mmap_base, i);

- if (!check_huge_shmem(mmap_base, FILE_SIZE, NR_PMD_PAGE, pmd_pagesize))
+ if (!check_huge_file(mmap_base, FILE_SIZE, NR_PMD_PAGE, pmd_pagesize))
ksft_exit_fail_msg("No shmem THP is allocated\n");

if (pthread_barrier_init(&ctl.barrier, NULL, NUM_READER_THREADS + 1) != 0)
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index f82673f5f6b47..f448278823678 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -53,7 +53,7 @@ struct mem_ops {
void *(*setup_area)(int nr_hpages);
void (*cleanup_area)(void *p, unsigned long size);
void (*fault)(void *p, unsigned long start, unsigned long end);
- bool (*check_huge)(void *addr, size_t len, int nr_hpages, unsigned long hpage_size);
+ bool (*check_huge)(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
const char *name;
};

@@ -314,12 +314,6 @@ static void anon_fault(void *p, unsigned long start, unsigned long end)
fill_memory(p, start, end);
}

-static bool anon_check_huge(void *addr, size_t len, int nr_hpages,
- unsigned long hpage_size)
-{
- return check_huge_anon(addr, len, nr_hpages, hpage_size);
-}
-
static void *file_setup_area_common(int nr_hpages, enum file_setup_ops setup)
{
const int open_opt = setup == FILE_SETUP_READ_ONLY_FS ? O_RDONLY : O_RDWR;
@@ -411,20 +405,6 @@ static void file_fault_write(void *p, unsigned long start, unsigned long end)
ksft_exit_fail_perror("madvise(MADV_POPULATE_WRITE)");
}

-static bool file_check_huge(void *addr, size_t len, int nr_hpages,
- unsigned long hpage_size)
-{
- switch (finfo.type) {
- case VMA_FILE:
- return check_huge_file(addr, len, nr_hpages, hpage_size);
- case VMA_SHMEM:
- return check_huge_shmem(addr, len, nr_hpages, hpage_size);
- default:
- ksft_exit_fail_msg("Unknown VMA type\n");
- return false;
- }
-}
-
static void *shmem_setup_area(int nr_hpages)
{
void *p;
@@ -448,17 +428,11 @@ static void shmem_cleanup_area(void *p, unsigned long size)
close(finfo.fd);
}

-static bool shmem_check_huge(void *addr, size_t len, int nr_hpages,
- unsigned long hpage_size)
-{
- return check_huge_shmem(addr, len, nr_hpages, hpage_size);
-}
-
static struct mem_ops __anon_ops = {
.setup_area = &anon_setup_area,
.cleanup_area = &anon_cleanup_area,
.fault = &anon_fault,
- .check_huge = &anon_check_huge,
+ .check_huge = &check_huge_anon,
.name = "anon",
};

@@ -466,7 +440,7 @@ static struct mem_ops __read_only_file_ops = {
.setup_area = &file_setup_read_only_area,
.cleanup_area = &file_cleanup_area,
.fault = &file_fault_read,
- .check_huge = &file_check_huge,
+ .check_huge = &check_huge_file,
.name = "file",
};

@@ -474,7 +448,7 @@ static struct mem_ops __read_write_file_read_ops = {
.setup_area = &file_setup_read_write_fs_read_area,
.cleanup_area = &file_cleanup_area,
.fault = &file_fault_read_and_flush,
- .check_huge = &file_check_huge,
+ .check_huge = &check_huge_file,
.name = "file",
};

@@ -482,7 +456,7 @@ static struct mem_ops __read_write_file_write_ops = {
.setup_area = &file_setup_read_write_fs_write_area,
.cleanup_area = &file_cleanup_area,
.fault = &file_fault_write,
- .check_huge = &file_check_huge,
+ .check_huge = &check_huge_file,
.name = "file",
};

@@ -490,7 +464,7 @@ static struct mem_ops __shmem_ops = {
.setup_area = &shmem_setup_area,
.cleanup_area = &shmem_cleanup_area,
.fault = &anon_fault,
- .check_huge = &shmem_check_huge,
+ .check_huge = &check_huge_file,
.name = "shmem",
};

diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
index 1fb967ef49854..a76851aced4d0 100644
--- a/tools/testing/selftests/mm/uffd-common.c
+++ b/tools/testing/selftests/mm/uffd-common.c
@@ -196,8 +196,8 @@ static void shmem_check_pmd_mapping(uffd_global_test_opts_t *gopts, void *p, int
{
size_t len = expect_nr_hpages * read_pmd_pagesize();

- if (!check_huge_shmem(gopts->area_dst_alias, len, expect_nr_hpages,
- read_pmd_pagesize()))
+ if (!check_huge_file(gopts->area_dst_alias, len, expect_nr_hpages,
+ read_pmd_pagesize()))
err("Did not find expected %d number of hugepages",
expect_nr_hpages);
}
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index a7c5caf6925e0..e31e88d5af76d 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -475,11 +475,6 @@ bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_FILE);
}

-bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size)
-{
- return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_FILE);
-}
-
int64_t allocate_transhuge(void *ptr, int pagemap_fd)
{
uint64_t ent[2];
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 9a49af88702e4..fc9c93235f6fa 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -92,7 +92,6 @@ uint64_t read_pmd_pagesize(void);
unsigned long rss_anon(void);
bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
-bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
int64_t allocate_transhuge(void *ptr, int pagemap_fd);
int pageflags_get(unsigned long pfn, int kpageflags_fd, uint64_t *flags);
int gather_folio_orders(char *vaddr_start, size_t len,

--
2.43.0