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Message-ID: <20250812155512.926011-3-ziy@nvidia.com>
Date: Tue, 12 Aug 2025 11:55:10 -0400
From: Zi Yan <ziy@...dia.com>
To: Wei Yang <richard.weiyang@...il.com>,
wang lian <lianux.mm@...il.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
David Hildenbrand <david@...hat.com>,
linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
Zi Yan <ziy@...dia.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Nico Pache <npache@...hat.com>,
Ryan Roberts <ryan.roberts@....com>,
Dev Jain <dev.jain@....com>,
Barry Song <baohua@...nel.org>,
Vlastimil Babka <vbabka@...e.cz>,
Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>,
Shuah Khan <shuah@...nel.org>,
linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: [PATCH v3 2/4] selftests/mm: add check_folio_orders() helper.
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@...dia.com>
---
.../selftests/mm/split_huge_page_test.c | 4 +-
tools/testing/selftests/mm/vm_util.c | 173 ++++++++++++++++++
tools/testing/selftests/mm/vm_util.h | 7 +
3 files changed, 181 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 5d07b0b89226..63ac82f0b9e0 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..4d952d1bc96d 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -338,6 +338,179 @@ 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)
+{
+ size_t count;
+
+ count = pread(kpageflags_fd, flags, sizeof(*flags),
+ pfn * sizeof(*flags));
+
+ if (count != sizeof(*flags))
+ return -1;
+
+ return 0;
+}
+
+static int get_page_flags(char *vaddr, int pagemap_fd, int kpageflags_fd,
+ uint64_t *flags)
+{
+ unsigned long pfn;
+
+ pfn = pagemap_get_pfn(pagemap_fd, 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 1;
+ }
+
+ if (get_pfn_flags(pfn, kpageflags_fd, flags))
+ return -1;
+
+ return 0;
+}
+
+/*
+ * gather_folio_orders - scan through [vaddr_start, len) and record folio orders
+ * @vaddr_start: start vaddr
+ * @len: range length
+ * @pagemap_fd: file descriptor to /proc/<pid>/pagemap
+ * @kpageflags_fd: file descriptor to /proc/kpageflags
+ * @orders: output folio order array
+ * @nr_orders: folio order array size
+ *
+ * gather_folio_orders() scan through [vaddr_start, len) and check all folios
+ * within the range and record their orders. All order-0 pages will be recorded.
+ * Non-present vaddr is skipped.
+ *
+ *
+ * Return: 0 - no error, -1 - unhandled cases
+ */
+static int gather_folio_orders(char *vaddr_start, size_t len,
+ int pagemap_fd, int kpageflags_fd,
+ int orders[], int nr_orders)
+{
+ uint64_t page_flags = 0;
+ int cur_order = -1;
+ char *vaddr;
+
+ if (!pagemap_fd || !kpageflags_fd)
+ return -1;
+ if (nr_orders <= 0)
+ return -1;
+
+ for (vaddr = vaddr_start; vaddr < vaddr_start + len;) {
+ char *next_folio_vaddr;
+ int status;
+
+ status = get_page_flags(vaddr, pagemap_fd, kpageflags_fd,
+ &page_flags);
+ if (status < 0)
+ return -1;
+
+ /* skip non present vaddr */
+ if (status == 1) {
+ vaddr += psize();
+ continue;
+ }
+
+ /* 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;
+
+ vaddr += psize();
+ 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_fd,
+ kpageflags_fd,
+ &page_flags)) >= 0) {
+ /*
+ * non present vaddr, next compound head page, or
+ * order-0 page
+ */
+ if (status == 1 ||
+ (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 < 0)
+ 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_fd,
+ int kpageflags_fd, 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_fd,
+ kpageflags_fd, vaddr_orders, nr_orders);
+ if (status)
+ goto out;
+
+ 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;
+ }
+
+out:
+ free(vaddr_orders);
+ 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
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