On 8/5/26 11:59 PM, Zi Yan wrote:
On Sat Aug 1, 2026 at 2:26 AM EDT, Baolin Wang wrote:
Implement mTHP-sized hugepage checking helpers using gather_folio_orders().
Also rename the existing PMD-sized huge page check function to
__check_pmd_huge() for clarity.
Signed-off-by: Baolin Wang <[email protected]>
---
tools/testing/selftests/mm/vm_util.c | 60 ++++++++++++++++++++++++++--
1 file changed, 56 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/mm/vm_util.c
b/tools/testing/selftests/mm/vm_util.c
index 09e5d5cabe21..1240d783669c 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -15,6 +15,10 @@
#define SMAP_FILE_PATH "/proc/self/smaps"
#define STATUS_FILE_PATH "/proc/self/status"
#define MAX_LINE_LENGTH 500
+#define PAGEMAP_PATH "/proc/self/pagemap"
+#define KPAGEFLAGS_PATH "/proc/kpageflags"
+#define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
This is a fast way of getting log2, but there is no check of the type of
nr_pages. What prevents one using it on a long variable?
At least you can convert nr_pages to unsigned int and add a comment.
Good point. Ack.
+#define NR_ORDERS 20
Why 20? mTHP orders can only be in [1, pmd_order - 1] and different arch
has different pmd_orders. check_large_folios() probably should just cap
NR_ORDERS at pmd_order.
I followed the NR_ORDERS definition in selftests/mm/hugepage_settings.h,
and I think this function is not only for mTHP. Other test cases may
also call it to get the count of large folios beyond PMD order in the
future.
unsigned int __page_size;
unsigned int __page_shift;
@@ -348,7 +352,7 @@ char *__get_smap_entry(void *addr, const char *pattern,
char *buf, size_t len)
return entry;
}
-bool __check_huge(void *addr, char *pattern, int nr_hpages,
+static bool __check_pmd_huge(void *addr, char *pattern, int nr_hpages,
uint64_t hpage_size)
{
char buffer[MAX_LINE_LENGTH];
@@ -366,19 +370,67 @@ bool __check_huge(void *addr, char *pattern, int
nr_hpages,
return thp == (nr_hpages * (hpage_size >> 10));
}
+static bool check_large_folios(void *addr, unsigned long size, int nr_hpages, uint64_t hpage_size)
+{
+ int order = 0, pagesize = getpagesize();
+ int nr_pages = hpage_size / pagesize;
+ int pagemap_fd, kpageflags_fd;
+ int orders[NR_ORDERS], status;
NR_ORDERS is a constant, so you can put orders on stack. I think you can
rename it to MAX_NR_ORDERS, use 20,
Sure.
and check pmd_order is not bigger
than MAX_NR_ORDERS.
I don't think we need this. As I mentioned above, I hope this function
can also be used in the future to get the number of large folios beyond
PMD order.
+ bool ret = false;
+
+ if (nr_pages > 0)
+ order = GET_ORDER(nr_pages);
This funciton can fail early if nr_pages is 0.
Ack.
+
+ if (!order || order >= NR_ORDERS)
+ ksft_exit_fail_msg("invalid order\n");
It should check against pmd_order.
Ditto.
+
+ memset(orders, 0, sizeof(int) * NR_ORDERS);
+ pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
+ if (pagemap_fd == -1)
+ ksft_exit_fail_msg("read pagemap fail\n");
+
+ kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY);
+ if (kpageflags_fd == -1) {
+ close(pagemap_fd);
+ ksft_exit_fail_msg("read kpageflags fail\n");
+ }
+
+ status = gather_folio_orders(addr, size, pagemap_fd,
+ kpageflags_fd, orders, NR_ORDERS);
+ if (status)
+ goto out;
+
+ if (orders[order] == nr_hpages)
+ ret = true;
+
+out:
+ close(pagemap_fd);
+ close(kpageflags_fd);
+ return ret;
+}
+
bool check_huge_anon(void *addr, unsigned long size, int nr_hpages, uint64_t
hpage_size)
{
- return __check_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size);
+ if (hpage_size == read_pmd_pagesize())
read_pmd_pagesize() can fail and return 0. Either you need a check here
or add a ksft_exit_fail_msg() in read_pmd_pagesize() to remove the
burden from all callers.
Ack.
+ return __check_pmd_huge(addr, "AnonHugePages: ", nr_hpages,
hpage_size);
+
+ return check_large_folios(addr, size, nr_hpages, hpage_size);
}
bool check_huge_file(void *addr, unsigned long size, int nr_hpages, uint64_t hpage_size)
{
- return __check_huge(addr, "FilePmdMapped:", nr_hpages, hpage_size);
+ if (hpage_size == read_pmd_pagesize())
+ return __check_pmd_huge(addr, "FilePmdMapped:", nr_hpages,
hpage_size);
+
+ return check_large_folios(addr, size, nr_hpages, hpage_size);
}
bool check_huge_shmem(void *addr, unsigned long size, int nr_hpages, uint64_t hpage_size)
{
- return __check_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size);
+ if (hpage_size == read_pmd_pagesize())
+ return __check_pmd_huge(addr, "ShmemPmdMapped:", nr_hpages,
hpage_size);
+
+ return check_large_folios(addr, size, nr_hpages, hpage_size);
}
int64_t allocate_transhuge(void *ptr, int pagemap_fd)
All read_pmd_pagesize()s above need to be handled.
Sure. Thanks for taking a look.
