On 12 Aug 2025, at 23:38, wang lian wrote:
On Aug 12, 2025, at 23:55, Zi Yan ziy@nvidia.com 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 | 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;
Nit. It seems redundant. Would you consider removing it for a bit more conciseness? This doesn't block my approval, of course. Reviewed-by: wang lian lianux.mm@gmail.com
Sure. Thanks.
Best Regards, Yan, Zi