diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c
index 2cb5441f29c7..1896c7d4f72e 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -1052,11 +1052,10 @@ static void test_simple(void)
 int sanity_tests(void)
 {
 	unsigned long long mem_size, vec_size;
-	long ret, fd, i, buf_size;
+	long ret, fd, i, buf_size, nr_pages;
 	struct page_region *vec;
 	char *mem, *fmem;
 	struct stat sbuf;
-	char *tmp_buf;
 
 	/* 1. wrong operation */
 	mem_size = 10 * page_size;
@@ -1167,14 +1166,14 @@ int sanity_tests(void)
 	if (fmem == MAP_FAILED)
 		ksft_exit_fail_msg("error nomem %d %s\n", errno, strerror(errno));
 
-	tmp_buf = malloc(sbuf.st_size);
-	memcpy(tmp_buf, fmem, sbuf.st_size);
+	nr_pages = (sbuf.st_size + page_size - 1) / page_size;
+	force_read_pages(fmem, nr_pages, page_size);
 
 	ret = pagemap_ioctl(fmem, sbuf.st_size, vec, vec_size, 0, 0,
 			    0, PAGEMAP_NON_WRITTEN_BITS, 0, PAGEMAP_NON_WRITTEN_BITS);
 
 	ksft_test_result(ret >= 0 && vec[0].start == (uintptr_t)fmem &&
-			 LEN(vec[0]) == ceilf((float)sbuf.st_size/page_size) &&
+			 LEN(vec[0]) == nr_pages &&
 			 (vec[0].categories & PAGE_IS_FILE),
 			 "%s Memory mapped file\n", __func__);