diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 7d69baeb93f4..cb32cf5d867e 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -105,6 +105,7 @@ TEST_GEN_FILES += guard-regions
 TEST_GEN_FILES += merge
 TEST_GEN_FILES += rmap
 TEST_GEN_FILES += folio_split_race_test
+TEST_GEN_FILES += folio_order_check
 TEST_GEN_FILES += soft-dirty
 
 ifeq ($(ARCH),x86_64)
diff --git a/tools/testing/selftests/mm/folio_order_check.c b/tools/testing/selftests/mm/folio_order_check.c
new file mode 100644
index 000000000000..5eafbcc1b4f3
--- /dev/null
+++ b/tools/testing/selftests/mm/folio_order_check.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Self-check for the vm_util folio-order helpers, is_backed_by_folio() and
+ * is_range_backed_by_order(), which the khugepaged mTHP cases use to detect
+ * collapse results.  For every anon THP order the kernel supports, fault
+ * memory in with only that order enabled and require the helpers to report
+ * exactly that order.
+ */
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "kselftest.h"
+#include "vm_util.h"
+#include <mm/hugepage_settings.h>
+
+static int pagemap_fd;
+static int kpageflags_fd;
+
+static char *alloc_aligned(size_t size)
+{
+	size_t len = size * 2;
+	char *p, *aligned;
+
+	p = mmap(NULL, len, PROT_READ | PROT_WRITE,
+		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (p == MAP_FAILED)
+		ksft_exit_fail_perror("mmap()");
+
+	aligned = (char *)ALIGN((uintptr_t)p, size);
+	if (aligned != p)
+		munmap(p, aligned - p);
+	if (aligned + size != p + len)
+		munmap(aligned + size, p + len - aligned - size);
+
+	return aligned;
+}
+
+static void check_order(int order)
+{
+	struct thp_settings settings = *thp_current_settings();
+	size_t size = psize() << order;
+	bool ok = true;
+	char *p;
+	int i;
+
+	for (i = 0; i < NR_ORDERS; i++)
+		settings.hugepages[i].enabled = THP_NEVER;
+	if (order)
+		settings.hugepages[order].enabled = THP_ALWAYS;
+	thp_push_settings(&settings);
+
+	p = alloc_aligned(size);
+	*p = 1;
+
+	if (!is_range_backed_by_order(p, size, order, pagemap_fd, kpageflags_fd)) {
+		ksft_print_msg("order %d not detected after fault\n", order);
+		ok = false;
+	}
+
+	/* A lower order must be rejected: the folio is larger */
+	if (order && is_range_backed_by_order(p, size, order - 1,
+					      pagemap_fd, kpageflags_fd)) {
+		ksft_print_msg("order %d also reported as order %d\n",
+			       order, order - 1);
+		ok = false;
+	}
+
+	/* A large folio must not pass as order 0 */
+	if (order && is_range_backed_by_order(p, size, 0,
+					      pagemap_fd, kpageflags_fd)) {
+		ksft_print_msg("order %d also reported as order 0\n", order);
+		ok = false;
+	}
+
+	munmap(p, size);
+	thp_pop_settings();
+
+	ksft_test_result(ok, "order %d classified\n", order);
+}
+
+int main(void)
+{
+	struct thp_settings settings;
+	unsigned long orders;
+	int order;
+
+	ksft_print_header();
+
+	if (!thp_available())
+		ksft_exit_skip("Transparent Hugepages not available\n");
+
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_perror("open(/proc/self/pagemap)");
+	kpageflags_fd = open("/proc/kpageflags", O_RDONLY);
+	if (kpageflags_fd < 0)
+		ksft_exit_skip("open(/proc/kpageflags) requires root\n");
+
+	orders = thp_supported_orders();
+	if (!orders)
+		ksft_exit_skip("No supported THP orders\n");
+
+	ksft_set_plan(__builtin_popcountl(orders) + 1);
+
+	thp_save_settings();
+	thp_read_settings(&settings);
+	/* Base of the settings stack; the bottom entry is never popped */
+	thp_push_settings(&settings);
+
+	check_order(0);
+	for (order = 1; order < NR_ORDERS; order++) {
+		if (!(orders & (1UL << order)))
+			continue;
+		check_order(order);
+	}
+
+	ksft_finished();
+}
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index fa1a651963fd..e5f273ca84c1 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -65,7 +65,6 @@ enum {
 #define HMM_PATH_MAX    64
 #define NTIMES		10
 
-#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
 /* Just the flags we need, copied from mm.h: */
 
 #ifndef FOLL_WRITE
diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
index a35e2b57e05b..d1d0989ed2ca 100644
--- a/tools/testing/selftests/mm/migration.c
+++ b/tools/testing/selftests/mm/migration.c
@@ -20,7 +20,6 @@
 
 #define TWOMEG		(2<<20)
 #define RUNTIME		(20)
-#define ALIGN(x, a)	(((x) + (a - 1)) & (~((a) - 1)))
 
 HUGETLB_SETUP_DEFAULT_PAGES(1)
 
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 0d8c93087d05..6b80cf2eab14 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -382,6 +382,8 @@ CATEGORY="pfnmap" run_test ./pfnmap
 # COW tests
 CATEGORY="cow" run_test ./cow
 
+CATEGORY="thp" run_test ./folio_order_check
+
 CATEGORY="thp" run_test ./khugepaged
 
 CATEGORY="thp" run_test ./khugepaged -s 2
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 0172003c16dc..ea48e6a7527e 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -12,6 +12,8 @@
 #include <mm/hugepage_settings.h>
 
 #define BIT_ULL(nr)                   (1ULL << (nr))
+#define ALIGN(x, a)                   (((x) + (a) - 1) & ~((a) - 1))
+
 #define PM_SOFT_DIRTY                 BIT_ULL(55)
 #define PM_MMAP_EXCLUSIVE             BIT_ULL(56)
 #define PM_UFFD_WP                    BIT_ULL(57)