[PATCH v1 2/3] selftests/mm: uffd-unit-tests support for hugepages > 2M

[Ryan Roberts <ryan.roberts@arm.com>]

uffd-unit-tests uses a memory area with a fixed 32M size. Then it
calculates the number of pages by dividing by page_size, which itself is
either the base page size or the PMD huge page size depending on the
test config. For the latter, we end up with nr_pages=1 for arm64 16K
base pages, and nr_pages=0 for 64K base pages. This doesn't end well.

So let's make the 32M size a floor and also ensure that we have at least
2 pages given the PMD size. With this change, the tests pass on arm64
64K base page size configuration.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/uffd-unit-tests.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 74c8bc02b506..6973e57b227a 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -26,6 +26,8 @@
 #define ALIGN_UP(x, align_to) \
 	((__typeof__(x))((((unsigned long)(x)) + ((align_to)-1)) & ~((align_to)-1)))
 
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+
 struct mem_type {
 	const char *name;
 	unsigned int mem_flag;
@@ -196,7 +198,8 @@ uffd_setup_environment(uffd_test_args_t *args, uffd_test_case_t *test,
 	else
 		page_size = psize();
 
-	nr_pages = UFFD_TEST_MEM_SIZE / page_size;
+	/* Ensure we have at least 2 pages */
+	nr_pages = MAX(UFFD_TEST_MEM_SIZE, page_size * 2) / page_size;
 	/* TODO: remove this global var.. it's so ugly */
 	nr_cpus = 1;
 
-- 
2.43.0