[PATCH v3 49/54] selftests/mm: uffd-unit-tests: add setup of HugeTLB pages

[Mike Rapoport <rppt@kernel.org>]

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

uffd-unit-tests skips HugeTLB tests if there are no free huge pages
prepared by a wrapper script.

Add setup of HugeTLB pages to the test and make sure that the original
settings are restored on the test exit.

Replace exit() calls with _exit() to avoid restoring HugeTLB settings in
the middle of test.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 tools/testing/selftests/mm/uffd-unit-tests.c | 31 +++++++++++++++++---
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 1a33db281f8a..20e1829db91f 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -305,7 +305,7 @@ static int pagemap_test_fork(uffd_global_test_opts_t *gopts, bool with_event, bo
 		if (test_pin)
 			unpin_pages(&args);
 		/* Succeed */
-		exit(0);
+		_exit(0);
 	}
 	waitpid(child, &result, 0);
 
@@ -773,7 +773,7 @@ static void uffd_sigbus_test_common(uffd_global_test_opts_t *gopts, bool wp)
 		err("fork");
 
 	if (!pid)
-		exit(faulting_process(gopts, 2, wp));
+		_exit(faulting_process(gopts, 2, wp));
 
 	waitpid(pid, &err, 0);
 	if (err)
@@ -827,7 +827,7 @@ static void uffd_events_test_common(uffd_global_test_opts_t *gopts, bool wp)
 		err("fork");
 
 	if (!pid)
-		exit(faulting_process(gopts, 0, wp));
+		_exit(faulting_process(gopts, 0, wp));
 
 	waitpid(pid, &err, 0);
 	if (err)
@@ -1706,11 +1706,32 @@ static int uffd_count_tests(int n_tests, int n_mems, const char *test_filter)
 	return count;
 }
 
+static unsigned long uffd_setup_hugetlb(void)
+{
+	unsigned long nr_hugepages, hp_size;
+
+	hugetlb_save_settings();
+	hp_size = default_huge_page_size();
+
+	if (!hp_size)
+		return 0;
+
+	/* need twice UFFD_TEST_MEM_SIZE, one for src area and one for dst */
+	nr_hugepages = 2 * MAX(UFFD_TEST_MEM_SIZE, hp_size * 2) / hp_size;
+	hugetlb_set_nr_default_pages(nr_hugepages);
+
+	if (hugetlb_free_default_pages() < nr_hugepages)
+		return 0;
+
+	return hp_size;
+}
+
 int main(int argc, char *argv[])
 {
 	int n_tests = sizeof(uffd_tests) / sizeof(uffd_test_case_t);
 	int n_mems = sizeof(mem_types) / sizeof(mem_type_t);
 	const char *test_filter = NULL;
+	unsigned long hugepage_size;
 	bool list_only = false;
 	uffd_test_case_t *test;
 	mem_type_t *mem_type;
@@ -1745,6 +1766,8 @@ int main(int argc, char *argv[])
 		return KSFT_PASS;
 	}
 
+	hugepage_size = uffd_setup_hugetlb();
+
 	ksft_print_header();
 	ksft_set_plan(uffd_count_tests(n_tests, n_mems, test_filter));
 
@@ -1771,7 +1794,7 @@ int main(int argc, char *argv[])
 			uffd_test_case_ops = test->test_case_ops;
 
 			if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) {
-				gopts.page_size = default_huge_page_size();
+				gopts.page_size = hugepage_size;
 				if (gopts.page_size == 0) {
 					uffd_test_skip("huge page size is 0, feature missing?");
 					continue;
-- 
2.53.0