[PATCH v8 10/10] selftests/mm/cow: Add tests for anonymous multi-size THP

[Ryan Roberts <ryan.roberts@xxxxxxx>]

Add tests similar to the existing PMD-sized THP tests, but which operate
on memory backed by (PTE-mapped) multi-size THP. This reuses all the
existing infrastructure. If the test suite detects that multi-size THP
is not supported by the kernel, the new tests are skipped.

Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
---
 tools/testing/selftests/mm/cow.c | 84 +++++++++++++++++++++++++++-----
 1 file changed, 72 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 4d0b5a125d3c..37b4d7d28ae9 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -29,15 +29,49 @@
 #include "../../../../mm/gup_test.h"
 #include "../kselftest.h"
 #include "vm_util.h"
+#include "thp_settings.h"
 
 static size_t pagesize;
 static int pagemap_fd;
 static size_t pmdsize;
+static int nr_thpsizes;
+static size_t thpsizes[20];
 static int nr_hugetlbsizes;
 static size_t hugetlbsizes[10];
 static int gup_fd;
 static bool has_huge_zeropage;
 
+static int sz2ord(size_t size)
+{
+	return __builtin_ctzll(size / pagesize);
+}
+
+static int detect_thp_sizes(size_t sizes[], int max)
+{
+	int count = 0;
+	unsigned long orders;
+	size_t kb;
+	int i;
+
+	/* thp not supported at all. */
+	if (!pmdsize)
+		return 0;
+
+	orders = 1UL << sz2ord(pmdsize);
+	orders |= thp_supported_orders();
+
+	for (i = 0; orders && count < max; i++) {
+		if (!(orders & (1UL << i)))
+			continue;
+		orders &= ~(1UL << i);
+		kb = (pagesize >> 10) << i;
+		sizes[count++] = kb * 1024;
+		ksft_print_msg("[INFO] detected THP size: %zu KiB\n", kb);
+	}
+
+	return count;
+}
+
 static void detect_huge_zeropage(void)
 {
 	int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
@@ -1101,15 +1135,27 @@ static void run_anon_test_case(struct test_case const *test_case)
 
 	run_with_base_page(test_case->fn, test_case->desc);
 	run_with_base_page_swap(test_case->fn, test_case->desc);
-	if (pmdsize) {
-		run_with_thp(test_case->fn, test_case->desc, pmdsize);
-		run_with_thp_swap(test_case->fn, test_case->desc, pmdsize);
-		run_with_pte_mapped_thp(test_case->fn, test_case->desc, pmdsize);
-		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, pmdsize);
-		run_with_single_pte_of_thp(test_case->fn, test_case->desc, pmdsize);
-		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, pmdsize);
-		run_with_partial_mremap_thp(test_case->fn, test_case->desc, pmdsize);
-		run_with_partial_shared_thp(test_case->fn, test_case->desc, pmdsize);
+	for (i = 0; i < nr_thpsizes; i++) {
+		size_t size = thpsizes[i];
+		struct thp_settings settings = *thp_current_settings();
+
+		settings.hugepages[sz2ord(pmdsize)].enabled = THP_NEVER;
+		settings.hugepages[sz2ord(size)].enabled = THP_ALWAYS;
+		thp_push_settings(&settings);
+
+		if (size == pmdsize) {
+			run_with_thp(test_case->fn, test_case->desc, size);
+			run_with_thp_swap(test_case->fn, test_case->desc, size);
+		}
+
+		run_with_pte_mapped_thp(test_case->fn, test_case->desc, size);
+		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, size);
+		run_with_single_pte_of_thp(test_case->fn, test_case->desc, size);
+		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, size);
+		run_with_partial_mremap_thp(test_case->fn, test_case->desc, size);
+		run_with_partial_shared_thp(test_case->fn, test_case->desc, size);
+
+		thp_pop_settings();
 	}
 	for (i = 0; i < nr_hugetlbsizes; i++)
 		run_with_hugetlb(test_case->fn, test_case->desc,
@@ -1130,8 +1176,9 @@ static int tests_per_anon_test_case(void)
 {
 	int tests = 2 + nr_hugetlbsizes;
 
+	tests += 6 * nr_thpsizes;
 	if (pmdsize)
-		tests += 8;
+		tests += 2;
 	return tests;
 }
 
@@ -1689,15 +1736,23 @@ static int tests_per_non_anon_test_case(void)
 int main(int argc, char **argv)
 {
 	int err;
+	struct thp_settings default_settings;
 
 	pagesize = getpagesize();
 	pmdsize = read_pmd_pagesize();
 	if (pmdsize) {
+		/* Only if THP is supported. */
+		thp_read_settings(&default_settings);
+		default_settings.hugepages[sz2ord(pmdsize)].enabled = THP_INHERIT;
+		thp_save_settings();
+		thp_push_settings(&default_settings);
+
 		ksft_print_msg("[INFO] detected PMD size: %zu KiB\n",
 			       pmdsize / 1024);
-		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
-			       pmdsize / 1024);
+
+		nr_thpsizes = detect_thp_sizes(thpsizes, ARRAY_SIZE(thpsizes));
 	}
+
 	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
 						    ARRAY_SIZE(hugetlbsizes));
 	detect_huge_zeropage();
@@ -1716,6 +1771,11 @@ int main(int argc, char **argv)
 	run_anon_thp_test_cases();
 	run_non_anon_test_cases();
 
+	if (pmdsize) {
+		/* Only if THP is supported. */
+		thp_restore_settings();
+	}
+
 	err = ksft_get_fail_cnt();
 	if (err)
 		ksft_exit_fail_msg("%d out of %d tests failed\n",
-- 
2.25.1