and rename it to is_backed_by_folio().
is_backed_by_folio() checks if the given vaddr is backed a folio with
a given order. It does so by:
1. getting the pfn of the vaddr;
2. checking kpageflags of the pfn;
if order is greater than 0:
3. checking kpageflags of the head pfn;
4. checking kpageflags of all tail pfns.
pmd_order is added to split_huge_page_test.c and replaces max_order.
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
.../selftests/mm/split_huge_page_test.c | 67 +++++++++++++------
tools/testing/selftests/mm/vm_util.c | 2 +-
tools/testing/selftests/mm/vm_util.h | 1 +
3 files changed, 48 insertions(+), 22 deletions(-)
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 63ac82f0b9e0..3aaf783f339f 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -25,6 +25,7 @@
uint64_t pagesize;
unsigned int pageshift;
uint64_t pmd_pagesize;
+unsigned int pmd_order;
#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
#define SMAP_PATH "/proc/self/smaps"
@@ -36,23 +37,48 @@ uint64_t pmd_pagesize;
#define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
-int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
+int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, int kpageflags_fd)
{
- uint64_t paddr;
- uint64_t page_flags;
+ unsigned long pfn_head;
+ uint64_t pfn_flags;
+ unsigned long pfn;
+ unsigned long i;
- if (pagemap_file) {
- pread(pagemap_file, &paddr, sizeof(paddr),
- ((long)vaddr >> pageshift) * sizeof(paddr));
+ if (!pagemap_fd || !kpageflags_fd)
+ return 0;
- if (kpageflags_file) {
- pread(kpageflags_file, &page_flags, sizeof(page_flags),
- PAGEMAP_PFN(paddr) * sizeof(page_flags));
+ pfn = pagemap_get_pfn(pagemap_fd, vaddr);
- return !!(page_flags & KPF_THP);
- }
+ if (pfn == -1UL)
+ return 0;
+
+ if (get_pfn_flags(pfn, kpageflags_fd, &pfn_flags))
+ return 0;
+
+ if (!order) {
+ if (pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))
+ return 0;
+ return 1;
}
- return 0;
+
+ if (!(pfn_flags & KPF_THP))
+ return 0;
+
+ pfn_head = pfn & ~((1 << order) - 1);
+
+ if (get_pfn_flags(pfn_head, kpageflags_fd, &pfn_flags))
+ return 0;
+
+ if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD)))
+ return 0;
+
+ for (i = 1; i < (1UL << order) - 1; i++) {
+ if (get_pfn_flags(pfn_head + i, kpageflags_fd, &pfn_flags))
+ return 0;
+ if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_TAIL)))
+ return 0;
+ }
+ return 1;
}
static void write_file(const char *path, const char *buf, size_t buflen)
@@ -233,7 +259,7 @@ void split_pte_mapped_thp(void)
thp_size = 0;
for (i = 0; i < pagesize * 4; i++)
if (i % pagesize == 0 &&
- is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
+ is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd))
thp_size++;
if (thp_size != 4)
@@ -250,7 +276,7 @@ void split_pte_mapped_thp(void)
ksft_exit_fail_msg("%ld byte corrupted\n", i);
if (i % pagesize == 0 &&
- is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
+ !is_backed_by_folio(&pte_mapped[i], 0, pagemap_fd, kpageflags_fd))
thp_size++;
}
@@ -522,7 +548,6 @@ int main(int argc, char **argv)
const char *fs_loc;
bool created_tmp;
int offset;
- unsigned int max_order;
unsigned int nr_pages;
unsigned int tests;
@@ -543,28 +568,28 @@ int main(int argc, char **argv)
ksft_exit_fail_msg("Reading PMD pagesize failed\n");
nr_pages = pmd_pagesize / pagesize;
- max_order = GET_ORDER(nr_pages);
- tests = 2 + (max_order - 1) + (2 * max_order) + (max_order - 1) * 4 + 2;
+ pmd_order = GET_ORDER(nr_pages);
+ tests = 2 + (pmd_order - 1) + (2 * pmd_order) + (pmd_order - 1) * 4 + 2;
ksft_set_plan(tests);
fd_size = 2 * pmd_pagesize;
split_pmd_zero_pages();
- for (i = 0; i < max_order; i++)
+ for (i = 0; i < pmd_order; i++)
if (i != 1)
split_pmd_thp_to_order(i);
split_pte_mapped_thp();
- for (i = 0; i < max_order; i++)
+ for (i = 0; i < pmd_order; i++)
split_file_backed_thp(i);
created_tmp = prepare_thp_fs(optional_xfs_path, fs_loc_template,
&fs_loc);
- for (i = max_order - 1; i >= 0; i--)
+ for (i = pmd_order - 1; i >= 0; i--)
split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, -1);
- for (i = 0; i < max_order; i++)
+ for (i = 0; i < pmd_order; i++)
for (offset = 0;
offset < nr_pages;
offset += MAX(nr_pages / 4, 1 << i))
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 4d952d1bc96d..193ba1a1a3cc 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -338,7 +338,7 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
return count;
}
-static int get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags)
+int get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags)
{
size_t count;
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 02e3f1e7065b..148b792cff0f 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -92,6 +92,7 @@ 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 get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags);
int uffd_register(int uffd, void *addr, uint64_t len,
bool miss, bool wp, bool minor);
--
2.47.2On Tue, Aug 12, 2025 at 11:55:11AM -0400, Zi Yan wrote:
>and rename it to is_backed_by_folio().
>
>is_backed_by_folio() checks if the given vaddr is backed a folio with
>a given order. It does so by:
>1. getting the pfn of the vaddr;
>2. checking kpageflags of the pfn;
>
>if order is greater than 0:
>3. checking kpageflags of the head pfn;
>4. checking kpageflags of all tail pfns.
>
>pmd_order is added to split_huge_page_test.c and replaces max_order.
>
>Signed-off-by: Zi Yan <ziy@nvidia.com>
>---
> .../selftests/mm/split_huge_page_test.c | 67 +++++++++++++------
> tools/testing/selftests/mm/vm_util.c | 2 +-
> tools/testing/selftests/mm/vm_util.h | 1 +
> 3 files changed, 48 insertions(+), 22 deletions(-)
>
>diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>index 63ac82f0b9e0..3aaf783f339f 100644
>--- a/tools/testing/selftests/mm/split_huge_page_test.c
>+++ b/tools/testing/selftests/mm/split_huge_page_test.c
>@@ -25,6 +25,7 @@
> uint64_t pagesize;
> unsigned int pageshift;
> uint64_t pmd_pagesize;
>+unsigned int pmd_order;
>
> #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
> #define SMAP_PATH "/proc/self/smaps"
>@@ -36,23 +37,48 @@ uint64_t pmd_pagesize;
>
> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>
>-int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>+int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, int kpageflags_fd)
> {
>- uint64_t paddr;
>- uint64_t page_flags;
>+ unsigned long pfn_head;
>+ uint64_t pfn_flags;
>+ unsigned long pfn;
>+ unsigned long i;
>
>- if (pagemap_file) {
>- pread(pagemap_file, &paddr, sizeof(paddr),
>- ((long)vaddr >> pageshift) * sizeof(paddr));
>+ if (!pagemap_fd || !kpageflags_fd)
>+ return 0;
The same in patch 2.
>
>- if (kpageflags_file) {
>- pread(kpageflags_file, &page_flags, sizeof(page_flags),
>- PAGEMAP_PFN(paddr) * sizeof(page_flags));
>+ pfn = pagemap_get_pfn(pagemap_fd, vaddr);
>
>- return !!(page_flags & KPF_THP);
>- }
>+ if (pfn == -1UL)
>+ return 0;
>+
>+ if (get_pfn_flags(pfn, kpageflags_fd, &pfn_flags))
>+ return 0;
>+
>+ if (!order) {
>+ if (pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))
>+ return 0;
>+ return 1;
> }
>- return 0;
>+
>+ if (!(pfn_flags & KPF_THP))
>+ return 0;
>+
>+ pfn_head = pfn & ~((1 << order) - 1);
>+
>+ if (get_pfn_flags(pfn_head, kpageflags_fd, &pfn_flags))
>+ return 0;
>+
>+ if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD)))
>+ return 0;
>+
>+ for (i = 1; i < (1UL << order) - 1; i++) {
Do we miss the last tail?
>+ if (get_pfn_flags(pfn_head + i, kpageflags_fd, &pfn_flags))
>+ return 0;
>+ if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_TAIL)))
>+ return 0;
>+ }
If this folio is larger than order, would it still return 1?
>+ return 1;
> }
>
> static void write_file(const char *path, const char *buf, size_t buflen)
>@@ -233,7 +259,7 @@ void split_pte_mapped_thp(void)
> thp_size = 0;
> for (i = 0; i < pagesize * 4; i++)
> if (i % pagesize == 0 &&
>- is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
>+ is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd))
> thp_size++;
>
> if (thp_size != 4)
>@@ -250,7 +276,7 @@ void split_pte_mapped_thp(void)
> ksft_exit_fail_msg("%ld byte corrupted\n", i);
>
> if (i % pagesize == 0 &&
>- is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
>+ !is_backed_by_folio(&pte_mapped[i], 0, pagemap_fd, kpageflags_fd))
> thp_size++;
> }
>
>@@ -522,7 +548,6 @@ int main(int argc, char **argv)
> const char *fs_loc;
> bool created_tmp;
> int offset;
>- unsigned int max_order;
> unsigned int nr_pages;
> unsigned int tests;
>
>@@ -543,28 +568,28 @@ int main(int argc, char **argv)
> ksft_exit_fail_msg("Reading PMD pagesize failed\n");
>
> nr_pages = pmd_pagesize / pagesize;
>- max_order = GET_ORDER(nr_pages);
>- tests = 2 + (max_order - 1) + (2 * max_order) + (max_order - 1) * 4 + 2;
>+ pmd_order = GET_ORDER(nr_pages);
>+ tests = 2 + (pmd_order - 1) + (2 * pmd_order) + (pmd_order - 1) * 4 + 2;
> ksft_set_plan(tests);
>
> fd_size = 2 * pmd_pagesize;
>
> split_pmd_zero_pages();
>
>- for (i = 0; i < max_order; i++)
>+ for (i = 0; i < pmd_order; i++)
> if (i != 1)
> split_pmd_thp_to_order(i);
>
> split_pte_mapped_thp();
>- for (i = 0; i < max_order; i++)
>+ for (i = 0; i < pmd_order; i++)
> split_file_backed_thp(i);
>
> created_tmp = prepare_thp_fs(optional_xfs_path, fs_loc_template,
> &fs_loc);
>- for (i = max_order - 1; i >= 0; i--)
>+ for (i = pmd_order - 1; i >= 0; i--)
> split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, -1);
>
>- for (i = 0; i < max_order; i++)
>+ for (i = 0; i < pmd_order; i++)
> for (offset = 0;
> offset < nr_pages;
> offset += MAX(nr_pages / 4, 1 << i))
>diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
>index 4d952d1bc96d..193ba1a1a3cc 100644
>--- a/tools/testing/selftests/mm/vm_util.c
>+++ b/tools/testing/selftests/mm/vm_util.c
>@@ -338,7 +338,7 @@ int detect_hugetlb_page_sizes(size_t sizes[], int max)
> return count;
> }
>
>-static int get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags)
>+int get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags)
> {
> size_t count;
>
>diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
>index 02e3f1e7065b..148b792cff0f 100644
>--- a/tools/testing/selftests/mm/vm_util.h
>+++ b/tools/testing/selftests/mm/vm_util.h
>@@ -92,6 +92,7 @@ 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 get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags);
>
> 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 13 Aug 2025, at 17:41, Wei Yang wrote:
> On Tue, Aug 12, 2025 at 11:55:11AM -0400, Zi Yan wrote:
>> and rename it to is_backed_by_folio().
>>
>> is_backed_by_folio() checks if the given vaddr is backed a folio with
>> a given order. It does so by:
>> 1. getting the pfn of the vaddr;
>> 2. checking kpageflags of the pfn;
>>
>> if order is greater than 0:
>> 3. checking kpageflags of the head pfn;
>> 4. checking kpageflags of all tail pfns.
>>
>> pmd_order is added to split_huge_page_test.c and replaces max_order.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> .../selftests/mm/split_huge_page_test.c | 67 +++++++++++++------
>> tools/testing/selftests/mm/vm_util.c | 2 +-
>> tools/testing/selftests/mm/vm_util.h | 1 +
>> 3 files changed, 48 insertions(+), 22 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
>> index 63ac82f0b9e0..3aaf783f339f 100644
>> --- a/tools/testing/selftests/mm/split_huge_page_test.c
>> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
>> @@ -25,6 +25,7 @@
>> uint64_t pagesize;
>> unsigned int pageshift;
>> uint64_t pmd_pagesize;
>> +unsigned int pmd_order;
>>
>> #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
>> #define SMAP_PATH "/proc/self/smaps"
>> @@ -36,23 +37,48 @@ uint64_t pmd_pagesize;
>>
>> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>>
>> -int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
>> +int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, int kpageflags_fd)
>> {
>> - uint64_t paddr;
>> - uint64_t page_flags;
>> + unsigned long pfn_head;
>> + uint64_t pfn_flags;
>> + unsigned long pfn;
>> + unsigned long i;
>>
>> - if (pagemap_file) {
>> - pread(pagemap_file, &paddr, sizeof(paddr),
>> - ((long)vaddr >> pageshift) * sizeof(paddr));
>> + if (!pagemap_fd || !kpageflags_fd)
>> + return 0;
>
> The same in patch 2.
Will fix it.
>
>>
>> - if (kpageflags_file) {
>> - pread(kpageflags_file, &page_flags, sizeof(page_flags),
>> - PAGEMAP_PFN(paddr) * sizeof(page_flags));
>> + pfn = pagemap_get_pfn(pagemap_fd, vaddr);
>>
>> - return !!(page_flags & KPF_THP);
>> - }
>> + if (pfn == -1UL)
>> + return 0;
>> +
>> + if (get_pfn_flags(pfn, kpageflags_fd, &pfn_flags))
>> + return 0;
>> +
>> + if (!order) {
>> + if (pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))
>> + return 0;
>> + return 1;
>> }
>> - return 0;
>> +
>> + if (!(pfn_flags & KPF_THP))
>> + return 0;
>> +
>> + pfn_head = pfn & ~((1 << order) - 1);
>> +
>> + if (get_pfn_flags(pfn_head, kpageflags_fd, &pfn_flags))
>> + return 0;
>> +
>> + if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD)))
>> + return 0;
>> +
>> + for (i = 1; i < (1UL << order) - 1; i++) {
>
> Do we miss the last tail?
Yes, will fix it.
>
>> + if (get_pfn_flags(pfn_head + i, kpageflags_fd, &pfn_flags))
>> + return 0;
>> + if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_TAIL)))
>> + return 0;
>> + }
>
> If this folio is larger than order, would it still return 1?
Yes, but it should be good enough for current use. Will add a comment about it.
Thanks for the review.
Best Regards,
Yan, Zi
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