The helper gathers an folio order statistics of folios within a virtual
address range and checks it against a given order list. It aims to provide
a more precise folio order check instead of just checking the existence of
PMD folios.
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
.../selftests/mm/split_huge_page_test.c | 4 +-
tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
tools/testing/selftests/mm/vm_util.h | 7 +
3 files changed, 141 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index cb364c5670c6..5ab488fab1cd 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -34,8 +34,6 @@ uint64_t pmd_pagesize;
#define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d"
#define PATH_FMT "%s,0x%lx,0x%lx,%d"
-#define PFN_MASK ((1UL<<55)-1)
-#define KPF_THP (1UL<<22)
#define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
@@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
if (kpageflags_file) {
pread(kpageflags_file, &page_flags, sizeof(page_flags),
- (paddr & PFN_MASK) * sizeof(page_flags));
+ PAGEMAP_PFN(paddr) * sizeof(page_flags));
return !!(page_flags & KPF_THP);
}
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 6a239aa413e2..41d50b74b2f6 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -338,6 +338,139 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
return count;
}
+static int get_page_flags(char *vaddr, int pagemap_file, int kpageflags_file,
+ uint64_t *flags)
+{
+ unsigned long pfn;
+ size_t count;
+
+ pfn = pagemap_get_pfn(pagemap_file, vaddr);
+ /*
+ * Treat non-present page as a page without any flag, so that
+ * gather_folio_orders() just record the current folio order.
+ */
+ if (pfn == -1UL) {
+ *flags = 0;
+ return 0;
+ }
+
+ count = pread(kpageflags_file, flags, sizeof(*flags),
+ pfn * sizeof(*flags));
+
+ if (count != sizeof(*flags))
+ return -1;
+
+ return 0;
+}
+
+static int gather_folio_orders(char *vaddr_start, size_t len,
+ int pagemap_file, int kpageflags_file,
+ int orders[], int nr_orders)
+{
+ uint64_t page_flags = 0;
+ int cur_order = -1;
+ char *vaddr;
+
+ if (!pagemap_file || !kpageflags_file)
+ return -1;
+ if (nr_orders <= 0)
+ return -1;
+
+ for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
+ char *next_folio_vaddr;
+ int status;
+
+ if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
+ return -1;
+
+ /* all order-0 pages with possible false postive (non folio) */
+ if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
+ orders[0]++;
+ vaddr += psize();
+ continue;
+ }
+
+ /* skip non thp compound pages */
+ if (!(page_flags & KPF_THP)) {
+ vaddr += psize();
+ continue;
+ }
+
+ /* vpn points to part of a THP at this point */
+ if (page_flags & KPF_COMPOUND_HEAD)
+ cur_order = 1;
+ else {
+ /* not a head nor a tail in a THP? */
+ if (!(page_flags & KPF_COMPOUND_TAIL))
+ return -1;
+ continue;
+ }
+
+ next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
+
+ if (next_folio_vaddr >= vaddr_start + len)
+ break;
+
+ while (!(status = get_page_flags(next_folio_vaddr, pagemap_file,
+ kpageflags_file,
+ &page_flags))) {
+ /* next compound head page or order-0 page */
+ if ((page_flags & KPF_COMPOUND_HEAD) ||
+ !(page_flags & (KPF_COMPOUND_HEAD |
+ KPF_COMPOUND_TAIL))) {
+ if (cur_order < nr_orders) {
+ orders[cur_order]++;
+ cur_order = -1;
+ vaddr = next_folio_vaddr;
+ }
+ break;
+ }
+
+ /* not a head nor a tail in a THP? */
+ if (!(page_flags & KPF_COMPOUND_TAIL))
+ return -1;
+
+ cur_order++;
+ next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
+ }
+
+ if (status)
+ return status;
+ }
+ if (cur_order > 0 && cur_order < nr_orders)
+ orders[cur_order]++;
+ return 0;
+}
+
+int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
+ int kpageflags_file, int orders[], int nr_orders)
+{
+ int *vaddr_orders;
+ int status;
+ int i;
+
+ vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
+
+ if (!vaddr_orders)
+ ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
+
+ memset(vaddr_orders, 0, sizeof(int) * nr_orders);
+ status = gather_folio_orders(vaddr_start, len, pagemap_file,
+ kpageflags_file, vaddr_orders, nr_orders);
+ if (status)
+ return status;
+
+ status = 0;
+ for (i = 0; i < nr_orders; i++)
+ if (vaddr_orders[i] != orders[i]) {
+ ksft_print_msg("order %d: expected: %d got %d\n", i,
+ orders[i], vaddr_orders[i]);
+ status = -1;
+ }
+
+ return status;
+}
+
/* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
bool miss, bool wp, bool minor, uint64_t *ioctls)
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 1843ad48d32b..02e3f1e7065b 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -18,6 +18,11 @@
#define PM_SWAP BIT_ULL(62)
#define PM_PRESENT BIT_ULL(63)
+#define KPF_COMPOUND_HEAD BIT_ULL(15)
+#define KPF_COMPOUND_TAIL BIT_ULL(16)
+#define KPF_THP BIT_ULL(22)
+
+
/*
* Ignore the checkpatch warning, we must read from x but don't want to do
* anything with it in order to trigger a read page fault. We therefore must use
@@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
int64_t allocate_transhuge(void *ptr, int pagemap_fd);
unsigned long default_huge_page_size(void);
int detect_hugetlb_page_sizes(size_t sizes[], int max);
+int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
+ int kpageflags_file, int orders[], int nr_orders);
int uffd_register(int uffd, void *addr, uint64_t len,
bool miss, bool wp, bool minor);
--
2.47.2
On 2025/8/9 03:01, Zi Yan wrote:
> The helper gathers an folio order statistics of folios within a virtual
> address range and checks it against a given order list. It aims to provide
> a more precise folio order check instead of just checking the existence of
> PMD folios.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> .../selftests/mm/split_huge_page_test.c | 4 +-
> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
> tools/testing/selftests/mm/vm_util.h | 7 +
> 3 files changed, 141 insertions(+), 3 deletions(-)
>
[snip]
> +
> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
> + int kpageflags_file, int orders[], int nr_orders)
> +{
> + int *vaddr_orders;
> + int status;
> + int i;
> +
> + vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
> +
> + if (!vaddr_orders)
> + ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
> +
> + memset(vaddr_orders, 0, sizeof(int) * nr_orders);
> + status = gather_folio_orders(vaddr_start, len, pagemap_file,
> + kpageflags_file, vaddr_orders, nr_orders);
> + if (status)
Missed calling free(vaddr_orders) before returning.
> + return status;
> +
> + status = 0;
> + for (i = 0; i < nr_orders; i++)
> + if (vaddr_orders[i] != orders[i]) {
> + ksft_print_msg("order %d: expected: %d got %d\n", i,
> + orders[i], vaddr_orders[i]);
> + status = -1;
> + }
> +
Ditto.
> + return status;
> +}
> +
> /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
> int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor, uint64_t *ioctls)
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index 1843ad48d32b..02e3f1e7065b 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -18,6 +18,11 @@
> #define PM_SWAP BIT_ULL(62)
> #define PM_PRESENT BIT_ULL(63)
>
> +#define KPF_COMPOUND_HEAD BIT_ULL(15)
> +#define KPF_COMPOUND_TAIL BIT_ULL(16)
> +#define KPF_THP BIT_ULL(22)
> +
> +
> /*
> * Ignore the checkpatch warning, we must read from x but don't want to do
> * anything with it in order to trigger a read page fault. We therefore must use
> @@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
> int64_t allocate_transhuge(void *ptr, int pagemap_fd);
> unsigned long default_huge_page_size(void);
> int detect_hugetlb_page_sizes(size_t sizes[], int max);
> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
> + int kpageflags_file, int orders[], int nr_orders);
>
> int uffd_register(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor);
On 11 Aug 2025, at 3:52, Baolin Wang wrote:
> On 2025/8/9 03:01, Zi Yan wrote:
>> The helper gathers an folio order statistics of folios within a virtual
>> address range and checks it against a given order list. It aims to provide
>> a more precise folio order check instead of just checking the existence of
>> PMD folios.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> .../selftests/mm/split_huge_page_test.c | 4 +-
>> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
>> tools/testing/selftests/mm/vm_util.h | 7 +
>> 3 files changed, 141 insertions(+), 3 deletions(-)
>>
>
> [snip]
>
>> +
>> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
>> + int kpageflags_file, int orders[], int nr_orders)
>> +{
>> + int *vaddr_orders;
>> + int status;
>> + int i;
>> +
>> + vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
>> +
>> + if (!vaddr_orders)
>> + ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
>> +
>> + memset(vaddr_orders, 0, sizeof(int) * nr_orders);
>> + status = gather_folio_orders(vaddr_start, len, pagemap_file,
>> + kpageflags_file, vaddr_orders, nr_orders);
>> + if (status)
>
> Missed calling free(vaddr_orders) before returning.
>
>> + return status;
>> +
>> + status = 0;
>> + for (i = 0; i < nr_orders; i++)
>> + if (vaddr_orders[i] != orders[i]) {
>> + ksft_print_msg("order %d: expected: %d got %d\n", i,
>> + orders[i], vaddr_orders[i]);
>> + status = -1;
>> + }
>> +
>
> Ditto.
>
>> + return status;
>> +}
>> +
Will add free() in the above two locations. Thank you for spotting them.
Best Regards,
Yan, Zi
On 8/9/25 12:31 AM, Zi Yan wrote:
> The helper gathers an folio order statistics of folios within a virtual
> address range and checks it against a given order list. It aims to provide
> a more precise folio order check instead of just checking the existence of
> PMD folios.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> .../selftests/mm/split_huge_page_test.c | 4 +-
> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
> tools/testing/selftests/mm/vm_util.h | 7 +
> 3 files changed, 141 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index cb364c5670c6..5ab488fab1cd 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -34,8 +34,6 @@ uint64_t pmd_pagesize;
> #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d"
> #define PATH_FMT "%s,0x%lx,0x%lx,%d"
>
> -#define PFN_MASK ((1UL<<55)-1)
> -#define KPF_THP (1UL<<22)
> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>
> int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
> @@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>
> if (kpageflags_file) {
> pread(kpageflags_file, &page_flags, sizeof(page_flags),
> - (paddr & PFN_MASK) * sizeof(page_flags));
> + PAGEMAP_PFN(paddr) * sizeof(page_flags));
>
> return !!(page_flags & KPF_THP);
> }
> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index 6a239aa413e2..41d50b74b2f6 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -338,6 +338,139 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
> return count;
> }
>
> +static int get_page_flags(char *vaddr, int pagemap_file, int kpageflags_file,
> + uint64_t *flags)
> +{
> + unsigned long pfn;
> + size_t count;
> +
> + pfn = pagemap_get_pfn(pagemap_file, vaddr);
> + /*
> + * Treat non-present page as a page without any flag, so that
> + * gather_folio_orders() just record the current folio order.
> + */
> + if (pfn == -1UL) {
> + *flags = 0;
> + return 0;
> + }
> +
> + count = pread(kpageflags_file, flags, sizeof(*flags),
> + pfn * sizeof(*flags));
> +
> + if (count != sizeof(*flags))
> + return -1;
> +
> + return 0;
> +}
> +
> +static int gather_folio_orders(char *vaddr_start, size_t len,
> + int pagemap_file, int kpageflags_file,
> + int orders[], int nr_orders)
> +{
> + uint64_t page_flags = 0;
> + int cur_order = -1;
> + char *vaddr;
> +
> + if (!pagemap_file || !kpageflags_file)
> + return -1;
> + if (nr_orders <= 0)
> + return -1;
> +
> + for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
> + char *next_folio_vaddr;
> + int status;
> +
> + if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
> + return -1;
> +
> + /* all order-0 pages with possible false postive (non folio) */
> + if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
> + orders[0]++;
> + vaddr += psize();
> + continue;
> + }
> +
> + /* skip non thp compound pages */
> + if (!(page_flags & KPF_THP)) {
> + vaddr += psize();
> + continue;
> + }
> +
> + /* vpn points to part of a THP at this point */
> + if (page_flags & KPF_COMPOUND_HEAD)
> + cur_order = 1;
> + else {
> + /* not a head nor a tail in a THP? */
> + if (!(page_flags & KPF_COMPOUND_TAIL))
> + return -1;
> + continue;
If KPF_COMPOUND_TAIL is set, do we use the same vaddr, or should we
advance to the next vaddr before continuing?
> + }
> +
> + next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
> +
> + if (next_folio_vaddr >= vaddr_start + len)
> + break;
> +
> + while (!(status = get_page_flags(next_folio_vaddr, pagemap_file,
> + kpageflags_file,
> + &page_flags))) {
> + /* next compound head page or order-0 page */
> + if ((page_flags & KPF_COMPOUND_HEAD) ||
> + !(page_flags & (KPF_COMPOUND_HEAD |
> + KPF_COMPOUND_TAIL))) {
> + if (cur_order < nr_orders) {
> + orders[cur_order]++;
> + cur_order = -1;
> + vaddr = next_folio_vaddr;
> + }
> + break;
> + }
> +
> + /* not a head nor a tail in a THP? */
> + if (!(page_flags & KPF_COMPOUND_TAIL))
> + return -1;
> +
> + cur_order++;
> + next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
> + }
> +
> + if (status)
> + return status;
> + }
> + if (cur_order > 0 && cur_order < nr_orders)
> + orders[cur_order]++;
> + return 0;
> +}
> +
> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
> + int kpageflags_file, int orders[], int nr_orders)
> +{
> + int *vaddr_orders;
> + int status;
> + int i;
> +
> + vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
> +
> + if (!vaddr_orders)
> + ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
> +
> + memset(vaddr_orders, 0, sizeof(int) * nr_orders);
> + status = gather_folio_orders(vaddr_start, len, pagemap_file,
> + kpageflags_file, vaddr_orders, nr_orders);
> + if (status)
> + return status;
> +
> + status = 0;
> + for (i = 0; i < nr_orders; i++)
> + if (vaddr_orders[i] != orders[i]) {
> + ksft_print_msg("order %d: expected: %d got %d\n", i,
> + orders[i], vaddr_orders[i]);
> + status = -1;
> + }
> +
> + return status;
> +}
> +
> /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
> int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor, uint64_t *ioctls)
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index 1843ad48d32b..02e3f1e7065b 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -18,6 +18,11 @@
> #define PM_SWAP BIT_ULL(62)
> #define PM_PRESENT BIT_ULL(63)
>
> +#define KPF_COMPOUND_HEAD BIT_ULL(15)
> +#define KPF_COMPOUND_TAIL BIT_ULL(16)
> +#define KPF_THP BIT_ULL(22)
> +
> +
> /*
> * Ignore the checkpatch warning, we must read from x but don't want to do
> * anything with it in order to trigger a read page fault. We therefore must use
> @@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
> int64_t allocate_transhuge(void *ptr, int pagemap_fd);
> unsigned long default_huge_page_size(void);
> int detect_hugetlb_page_sizes(size_t sizes[], int max);
> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
> + int kpageflags_file, int orders[], int nr_orders);
>
> int uffd_register(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor);
On 10 Aug 2025, at 12:49, Donet Tom wrote:
> On 8/9/25 12:31 AM, Zi Yan wrote:
>> The helper gathers an folio order statistics of folios within a virtual
>> address range and checks it against a given order list. It aims to provide
>> a more precise folio order check instead of just checking the existence of
>> PMD folios.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> .../selftests/mm/split_huge_page_test.c | 4 +-
>> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
>> tools/testing/selftests/mm/vm_util.h | 7 +
>> 3 files changed, 141 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>> index cb364c5670c6..5ab488fab1cd 100644
>> --- a/tools/testing/selftests/mm/split_huge_page_test.c
>> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
>> @@ -34,8 +34,6 @@ uint64_t pmd_pagesize;
>> #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d"
>> #define PATH_FMT "%s,0x%lx,0x%lx,%d"
>> -#define PFN_MASK ((1UL<<55)-1)
>> -#define KPF_THP (1UL<<22)
>> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>> int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>> @@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>> if (kpageflags_file) {
>> pread(kpageflags_file, &page_flags, sizeof(page_flags),
>> - (paddr & PFN_MASK) * sizeof(page_flags));
>> + PAGEMAP_PFN(paddr) * sizeof(page_flags));
>> return !!(page_flags & KPF_THP);
>> }
>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>> index 6a239aa413e2..41d50b74b2f6 100644
>> --- a/tools/testing/selftests/mm/vm_util.c
>> +++ b/tools/testing/selftests/mm/vm_util.c
>> @@ -338,6 +338,139 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
>> return count;
>> }
>> +static int get_page_flags(char *vaddr, int pagemap_file, int kpageflags_file,
>> + uint64_t *flags)
>> +{
>> + unsigned long pfn;
>> + size_t count;
>> +
>> + pfn = pagemap_get_pfn(pagemap_file, vaddr);
>> + /*
>> + * Treat non-present page as a page without any flag, so that
>> + * gather_folio_orders() just record the current folio order.
>> + */
>> + if (pfn == -1UL) {
>> + *flags = 0;
>> + return 0;
>> + }
>> +
>> + count = pread(kpageflags_file, flags, sizeof(*flags),
>> + pfn * sizeof(*flags));
>> +
>> + if (count != sizeof(*flags))
>> + return -1;
>> +
>> + return 0;
>> +}
>> +
>> +static int gather_folio_orders(char *vaddr_start, size_t len,
>> + int pagemap_file, int kpageflags_file,
>> + int orders[], int nr_orders)
>> +{
>> + uint64_t page_flags = 0;
>> + int cur_order = -1;
>> + char *vaddr;
>> +
>> + if (!pagemap_file || !kpageflags_file)
>> + return -1;
>> + if (nr_orders <= 0)
>> + return -1;
>> +
>> + for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
>> + char *next_folio_vaddr;
>> + int status;
>> +
>> + if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
>> + return -1;
>> +
>> + /* all order-0 pages with possible false postive (non folio) */
>> + if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
>> + orders[0]++;
>> + vaddr += psize();
>> + continue;
>> + }
>> +
>> + /* skip non thp compound pages */
>> + if (!(page_flags & KPF_THP)) {
>> + vaddr += psize();
>> + continue;
>> + }
>> +
>> + /* vpn points to part of a THP at this point */
>> + if (page_flags & KPF_COMPOUND_HEAD)
>> + cur_order = 1;
>> + else {
>> + /* not a head nor a tail in a THP? */
>> + if (!(page_flags & KPF_COMPOUND_TAIL))
>> + return -1;
>> + continue;
>
> If KPF_COMPOUND_TAIL is set, do we use the same vaddr, or should we advance to the next vaddr before continuing?
Yeah, I missed a vaddr += psize() here. Thank you for pointing this out.
Best Regards,
Yan, Zi
On Fri, Aug 08, 2025 at 03:01:43PM -0400, Zi Yan wrote:
>The helper gathers an folio order statistics of folios within a virtual
>address range and checks it against a given order list. It aims to provide
>a more precise folio order check instead of just checking the existence of
>PMD folios.
>
>Signed-off-by: Zi Yan <ziy@nvidia.com>
>---
> .../selftests/mm/split_huge_page_test.c | 4 +-
> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
> tools/testing/selftests/mm/vm_util.h | 7 +
> 3 files changed, 141 insertions(+), 3 deletions(-)
>
>diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>index cb364c5670c6..5ab488fab1cd 100644
>--- a/tools/testing/selftests/mm/split_huge_page_test.c
>+++ b/tools/testing/selftests/mm/split_huge_page_test.c
>@@ -34,8 +34,6 @@ uint64_t pmd_pagesize;
> #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d"
> #define PATH_FMT "%s,0x%lx,0x%lx,%d"
>
>-#define PFN_MASK ((1UL<<55)-1)
>-#define KPF_THP (1UL<<22)
> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>
> int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>@@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>
> if (kpageflags_file) {
> pread(kpageflags_file, &page_flags, sizeof(page_flags),
>- (paddr & PFN_MASK) * sizeof(page_flags));
>+ PAGEMAP_PFN(paddr) * sizeof(page_flags));
>
is_backed_by_thp() shares similar logic as get_page_flags(), I am thinking we can
leverage get_page_flags() here.
> return !!(page_flags & KPF_THP);
> }
>diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>index 6a239aa413e2..41d50b74b2f6 100644
>--- a/tools/testing/selftests/mm/vm_util.c
>+++ b/tools/testing/selftests/mm/vm_util.c
>@@ -338,6 +338,139 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
> return count;
> }
>
>+static int get_page_flags(char *vaddr, int pagemap_file, int kpageflags_file,
>+ uint64_t *flags)
>+{
Nit.
In vm_util.c, we usually name the file descriptor as xxx_fd.
>+ unsigned long pfn;
>+ size_t count;
>+
>+ pfn = pagemap_get_pfn(pagemap_file, vaddr);
>+ /*
>+ * Treat non-present page as a page without any flag, so that
>+ * gather_folio_orders() just record the current folio order.
>+ */
>+ if (pfn == -1UL) {
>+ *flags = 0;
>+ return 0;
>+ }
>+
>+ count = pread(kpageflags_file, flags, sizeof(*flags),
>+ pfn * sizeof(*flags));
>+
>+ if (count != sizeof(*flags))
>+ return -1;
>+
>+ return 0;
>+}
>+
Maybe a simple document here would be helpful.
>+static int gather_folio_orders(char *vaddr_start, size_t len,
>+ int pagemap_file, int kpageflags_file,
>+ int orders[], int nr_orders)
>+{
>+ uint64_t page_flags = 0;
>+ int cur_order = -1;
>+ char *vaddr;
>+
>+ if (!pagemap_file || !kpageflags_file)
>+ return -1;
>+ if (nr_orders <= 0)
>+ return -1;
>+
>+ for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
>+ char *next_folio_vaddr;
>+ int status;
>+
>+ if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
>+ return -1;
>+
>+ /* all order-0 pages with possible false postive (non folio) */
>+ if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
>+ orders[0]++;
>+ vaddr += psize();
>+ continue;
>+ }
>+
>+ /* skip non thp compound pages */
>+ if (!(page_flags & KPF_THP)) {
>+ vaddr += psize();
>+ continue;
>+ }
>+
>+ /* vpn points to part of a THP at this point */
>+ if (page_flags & KPF_COMPOUND_HEAD)
>+ cur_order = 1;
>+ else {
>+ /* not a head nor a tail in a THP? */
>+ if (!(page_flags & KPF_COMPOUND_TAIL))
>+ return -1;
>+ continue;
>+ }
>+
>+ next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
>+
>+ if (next_folio_vaddr >= vaddr_start + len)
>+ break;
Would we skip order 1 folio at the last position?
For example, vaddr_start is 0x2000, len is 0x2000 and the folio at vaddr_start
is an order 1 folio, whose size is exactly 0x2000.
Then we will get next_folio_vaddr == vaddr_start + len.
Could that happen?
>+
>+ while (!(status = get_page_flags(next_folio_vaddr, pagemap_file,
>+ kpageflags_file,
>+ &page_flags))) {
>+ /* next compound head page or order-0 page */
>+ if ((page_flags & KPF_COMPOUND_HEAD) ||
>+ !(page_flags & (KPF_COMPOUND_HEAD |
>+ KPF_COMPOUND_TAIL))) {
Maybe we can put them into one line.
>+ if (cur_order < nr_orders) {
>+ orders[cur_order]++;
>+ cur_order = -1;
>+ vaddr = next_folio_vaddr;
>+ }
>+ break;
>+ }
>+
>+ /* not a head nor a tail in a THP? */
>+ if (!(page_flags & KPF_COMPOUND_TAIL))
>+ return -1;
>+
>+ cur_order++;
>+ next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
>+ }
The while loop share similar logic as the outer for loop. Is it possible
reduce some duplication?
>+
>+ if (status)
>+ return status;
>+ }
>+ if (cur_order > 0 && cur_order < nr_orders)
>+ orders[cur_order]++;
>+ return 0;
>+}
>+
>+int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
>+ int kpageflags_file, int orders[], int nr_orders)
>+{
>+ int *vaddr_orders;
>+ int status;
>+ int i;
>+
>+ vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
>+
I took a look into thp_setting.h, where defines an array with NR_ORDERS
element which is 20. Maybe we can leverage it here, since we don't expect the
order to be larger.
>+ if (!vaddr_orders)
>+ ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
>+
>+ memset(vaddr_orders, 0, sizeof(int) * nr_orders);
>+ status = gather_folio_orders(vaddr_start, len, pagemap_file,
>+ kpageflags_file, vaddr_orders, nr_orders);
>+ if (status)
>+ return status;
>+
>+ status = 0;
>+ for (i = 0; i < nr_orders; i++)
>+ if (vaddr_orders[i] != orders[i]) {
>+ ksft_print_msg("order %d: expected: %d got %d\n", i,
>+ orders[i], vaddr_orders[i]);
>+ status = -1;
>+ }
>+
>+ return status;
>+}
>+
> /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
> int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor, uint64_t *ioctls)
>diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
>index 1843ad48d32b..02e3f1e7065b 100644
>--- a/tools/testing/selftests/mm/vm_util.h
>+++ b/tools/testing/selftests/mm/vm_util.h
>@@ -18,6 +18,11 @@
> #define PM_SWAP BIT_ULL(62)
> #define PM_PRESENT BIT_ULL(63)
>
>+#define KPF_COMPOUND_HEAD BIT_ULL(15)
>+#define KPF_COMPOUND_TAIL BIT_ULL(16)
>+#define KPF_THP BIT_ULL(22)
>+
>+
> /*
> * Ignore the checkpatch warning, we must read from x but don't want to do
> * anything with it in order to trigger a read page fault. We therefore must use
>@@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
> int64_t allocate_transhuge(void *ptr, int pagemap_fd);
> unsigned long default_huge_page_size(void);
> int detect_hugetlb_page_sizes(size_t sizes[], int max);
>+int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
>+ int kpageflags_file, int orders[], int nr_orders);
>
> int uffd_register(int uffd, void *addr, uint64_t len,
> bool miss, bool wp, bool minor);
>--
>2.47.2
--
Wei Yang
Help you, Help me
On 9 Aug 2025, at 16:18, Wei Yang wrote:
> On Fri, Aug 08, 2025 at 03:01:43PM -0400, Zi Yan wrote:
>> The helper gathers an folio order statistics of folios within a virtual
>> address range and checks it against a given order list. It aims to provide
>> a more precise folio order check instead of just checking the existence of
>> PMD folios.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> .../selftests/mm/split_huge_page_test.c | 4 +-
>> tools/testing/selftests/mm/vm_util.c | 133 ++++++++++++++++++
>> tools/testing/selftests/mm/vm_util.h | 7 +
>> 3 files changed, 141 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>> index cb364c5670c6..5ab488fab1cd 100644
>> --- a/tools/testing/selftests/mm/split_huge_page_test.c
>> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
>> @@ -34,8 +34,6 @@ uint64_t pmd_pagesize;
>> #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d"
>> #define PATH_FMT "%s,0x%lx,0x%lx,%d"
>>
>> -#define PFN_MASK ((1UL<<55)-1)
>> -#define KPF_THP (1UL<<22)
>> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>>
>> int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>> @@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>>
>> if (kpageflags_file) {
>> pread(kpageflags_file, &page_flags, sizeof(page_flags),
>> - (paddr & PFN_MASK) * sizeof(page_flags));
>> + PAGEMAP_PFN(paddr) * sizeof(page_flags));
>>
>
> is_backed_by_thp() shares similar logic as get_page_flags(), I am thinking we can
> leverage get_page_flags() here.
I was lazy for this one. I will use check_folio_orders() in the next version.
>
>> return !!(page_flags & KPF_THP);
>> }
>> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>> index 6a239aa413e2..41d50b74b2f6 100644
>> --- a/tools/testing/selftests/mm/vm_util.c
>> +++ b/tools/testing/selftests/mm/vm_util.c
>> @@ -338,6 +338,139 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
>> return count;
>> }
>>
>> +static int get_page_flags(char *vaddr, int pagemap_file, int kpageflags_file,
>> + uint64_t *flags)
>> +{
>
> Nit.
>
> In vm_util.c, we usually name the file descriptor as xxx_fd.
OK. I can rename them.
>
>> + unsigned long pfn;
>> + size_t count;
>> +
>> + pfn = pagemap_get_pfn(pagemap_file, vaddr);
>> + /*
>> + * Treat non-present page as a page without any flag, so that
>> + * gather_folio_orders() just record the current folio order.
>> + */
>> + if (pfn == -1UL) {
>> + *flags = 0;
>> + return 0;
>> + }
>> +
>> + count = pread(kpageflags_file, flags, sizeof(*flags),
>> + pfn * sizeof(*flags));
>> +
>> + if (count != sizeof(*flags))
>> + return -1;
>> +
>> + return 0;
>> +}
>> +
>
> Maybe a simple document here would be helpful.
Will do.
>
>> +static int gather_folio_orders(char *vaddr_start, size_t len,
>> + int pagemap_file, int kpageflags_file,
>> + int orders[], int nr_orders)
>> +{
>> + uint64_t page_flags = 0;
>> + int cur_order = -1;
>> + char *vaddr;
>> +
>> + if (!pagemap_file || !kpageflags_file)
>> + return -1;
>> + if (nr_orders <= 0)
>> + return -1;
>> +
>> + for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
>> + char *next_folio_vaddr;
>> + int status;
>> +
>> + if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
>> + return -1;
>> +
>> + /* all order-0 pages with possible false postive (non folio) */
>> + if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
>> + orders[0]++;
>> + vaddr += psize();
>> + continue;
>> + }
>> +
>> + /* skip non thp compound pages */
>> + if (!(page_flags & KPF_THP)) {
>> + vaddr += psize();
>> + continue;
>> + }
>> +
>> + /* vpn points to part of a THP at this point */
>> + if (page_flags & KPF_COMPOUND_HEAD)
>> + cur_order = 1;
>> + else {
>> + /* not a head nor a tail in a THP? */
>> + if (!(page_flags & KPF_COMPOUND_TAIL))
>> + return -1;
>> + continue;
>> + }
>> +
>> + next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
>> +
>> + if (next_folio_vaddr >= vaddr_start + len)
>> + break;
>
> Would we skip order 1 folio at the last position?
>
> For example, vaddr_start is 0x2000, len is 0x2000 and the folio at vaddr_start
> is an order 1 folio, whose size is exactly 0x2000.
>
> Then we will get next_folio_vaddr == vaddr_start + len.
>
> Could that happen?
No. After the loop, there is code checking cur_order and updating orders[].
>
>> +
>> + while (!(status = get_page_flags(next_folio_vaddr, pagemap_file,
>> + kpageflags_file,
>> + &page_flags))) {
>> + /* next compound head page or order-0 page */
>> + if ((page_flags & KPF_COMPOUND_HEAD) ||
>> + !(page_flags & (KPF_COMPOUND_HEAD |
>> + KPF_COMPOUND_TAIL))) {
>
> Maybe we can put them into one line.
Sure.
>
>> + if (cur_order < nr_orders) {
>> + orders[cur_order]++;
>> + cur_order = -1;
>> + vaddr = next_folio_vaddr;
>> + }
>> + break;
>> + }
>> +
>> + /* not a head nor a tail in a THP? */
>> + if (!(page_flags & KPF_COMPOUND_TAIL))
>> + return -1;
>> +
>> + cur_order++;
>> + next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
>> + }
>
> The while loop share similar logic as the outer for loop. Is it possible
> reduce some duplication?
Outer loop is to filter order-0 and non head pages and while loop is
to find current THP/mTHP orders. It would be messy to combine them.
But feel free to provide ideas if you see a way.
>
>> +
>> + if (status)
>> + return status;
>> + }
>> + if (cur_order > 0 && cur_order < nr_orders)
>> + orders[cur_order]++;
>> + return 0;
>> +}
>> +
>> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
>> + int kpageflags_file, int orders[], int nr_orders)
>> +{
>> + int *vaddr_orders;
>> + int status;
>> + int i;
>> +
>> + vaddr_orders = (int *)malloc(sizeof(int) * nr_orders);
>> +
>
> I took a look into thp_setting.h, where defines an array with NR_ORDERS
> element which is 20. Maybe we can leverage it here, since we don't expect the
> order to be larger.
>
20 is too large for current use. We can revisit this when the function
gets more users.
>> + if (!vaddr_orders)
>> + ksft_exit_fail_msg("Cannot allocate memory for vaddr_orders");
>> +
>> + memset(vaddr_orders, 0, sizeof(int) * nr_orders);
>> + status = gather_folio_orders(vaddr_start, len, pagemap_file,
>> + kpageflags_file, vaddr_orders, nr_orders);
>> + if (status)
>> + return status;
>> +
>> + status = 0;
>> + for (i = 0; i < nr_orders; i++)
>> + if (vaddr_orders[i] != orders[i]) {
>> + ksft_print_msg("order %d: expected: %d got %d\n", i,
>> + orders[i], vaddr_orders[i]);
>> + status = -1;
>> + }
>> +
>> + return status;
>> +}
>> +
>> /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
>> int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
>> bool miss, bool wp, bool minor, uint64_t *ioctls)
>> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
>> index 1843ad48d32b..02e3f1e7065b 100644
>> --- a/tools/testing/selftests/mm/vm_util.h
>> +++ b/tools/testing/selftests/mm/vm_util.h
>> @@ -18,6 +18,11 @@
>> #define PM_SWAP BIT_ULL(62)
>> #define PM_PRESENT BIT_ULL(63)
>>
>> +#define KPF_COMPOUND_HEAD BIT_ULL(15)
>> +#define KPF_COMPOUND_TAIL BIT_ULL(16)
>> +#define KPF_THP BIT_ULL(22)
>> +
>> +
>> /*
>> * Ignore the checkpatch warning, we must read from x but don't want to do
>> * anything with it in order to trigger a read page fault. We therefore must use
>> @@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
>> int64_t allocate_transhuge(void *ptr, int pagemap_fd);
>> unsigned long default_huge_page_size(void);
>> int detect_hugetlb_page_sizes(size_t sizes[], int max);
>> +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_file,
>> + int kpageflags_file, int orders[], int nr_orders);
>>
>> int uffd_register(int uffd, void *addr, uint64_t len,
>> bool miss, bool wp, bool minor);
>> --
>> 2.47.2
>
> --
> Wei Yang
> Help you, Help me
Best Regards,
Yan, Zi
On Mon, Aug 11, 2025 at 02:39:08PM -0400, Zi Yan wrote:
[...]
>>> +static int gather_folio_orders(char *vaddr_start, size_t len,
>>> + int pagemap_file, int kpageflags_file,
>>> + int orders[], int nr_orders)
>>> +{
>>> + uint64_t page_flags = 0;
>>> + int cur_order = -1;
>>> + char *vaddr;
>>> +
>>> + if (!pagemap_file || !kpageflags_file)
>>> + return -1;
>>> + if (nr_orders <= 0)
>>> + return -1;
>>> +
>>> + for (vaddr = vaddr_start; vaddr < vaddr_start + len; ) {
>>> + char *next_folio_vaddr;
>>> + int status;
>>> +
>>> + if (get_page_flags(vaddr, pagemap_file, kpageflags_file, &page_flags))
>>> + return -1;
>>> +
>>> + /* all order-0 pages with possible false postive (non folio) */
>>> + if (!(page_flags & (KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))) {
>>> + orders[0]++;
>>> + vaddr += psize();
>>> + continue;
>>> + }
>>> +
>>> + /* skip non thp compound pages */
>>> + if (!(page_flags & KPF_THP)) {
>>> + vaddr += psize();
>>> + continue;
>>> + }
>>> +
>>> + /* vpn points to part of a THP at this point */
>>> + if (page_flags & KPF_COMPOUND_HEAD)
>>> + cur_order = 1;
>>> + else {
>>> + /* not a head nor a tail in a THP? */
>>> + if (!(page_flags & KPF_COMPOUND_TAIL))
>>> + return -1;
>>> + continue;
>>> + }
>>> +
>>> + next_folio_vaddr = vaddr + (1UL << (cur_order + pshift()));
>>> +
>>> + if (next_folio_vaddr >= vaddr_start + len)
>>> + break;
>>
>> Would we skip order 1 folio at the last position?
>>
>> For example, vaddr_start is 0x2000, len is 0x2000 and the folio at vaddr_start
>> is an order 1 folio, whose size is exactly 0x2000.
>>
>> Then we will get next_folio_vaddr == vaddr_start + len.
>>
>> Could that happen?
>
>No. After the loop, there is code checking cur_order and updating orders[].
>
Oh, I missed this.
--
Wei Yang
Help you, Help me
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