1 files changed, 71 insertions, 0 deletions

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index e5e8dafc9d94..eb6d1b9fc362 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -84,6 +84,76 @@ static void write_debugfs(const char *fmt, ...)
 	write_file(SPLIT_DEBUGFS, input, ret + 1);
 }
 
+static char *allocate_zero_filled_hugepage(size_t len)
+{
+	char *result;
+	size_t i;
+
+	result = memalign(pmd_pagesize, len);
+	if (!result) {
+		printf("Fail to allocate memory\n");
+		exit(EXIT_FAILURE);
+	}
+
+	madvise(result, len, MADV_HUGEPAGE);
+
+	for (i = 0; i < len; i++)
+		result[i] = (char)0;
+
+	return result;
+}
+
+static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len)
+{
+	unsigned long rss_anon_before, rss_anon_after;
+	size_t i;
+
+	if (!check_huge_anon(one_page, 4, pmd_pagesize)) {
+		printf("No THP is allocated\n");
+		exit(EXIT_FAILURE);
+	}
+
+	rss_anon_before = rss_anon();
+	if (!rss_anon_before) {
+		printf("No RssAnon is allocated before split\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* split all THPs */
+	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
+		      (uint64_t)one_page + len, 0);
+
+	for (i = 0; i < len; i++)
+		if (one_page[i] != (char)0) {
+			printf("%ld byte corrupted\n", i);
+			exit(EXIT_FAILURE);
+		}
+
+	if (!check_huge_anon(one_page, 0, pmd_pagesize)) {
+		printf("Still AnonHugePages not split\n");
+		exit(EXIT_FAILURE);
+	}
+
+	rss_anon_after = rss_anon();
+	if (rss_anon_after >= rss_anon_before) {
+		printf("Incorrect RssAnon value. Before: %ld After: %ld\n",
+		       rss_anon_before, rss_anon_after);
+		exit(EXIT_FAILURE);
+	}
+}
+
+void split_pmd_zero_pages(void)
+{
+	char *one_page;
+	int nr_hpages = 4;
+	size_t len = nr_hpages * pmd_pagesize;
+
+	one_page = allocate_zero_filled_hugepage(len);
+	verify_rss_anon_split_huge_page_all_zeroes(one_page, nr_hpages, len);
+	printf("Split zero filled huge pages successful\n");
+	free(one_page);
+}
+
 void split_pmd_thp(void)
 {
 	char *one_page;
@@ -431,6 +501,7 @@ int main(int argc, char **argv)
 
 	fd_size = 2 * pmd_pagesize;
 
+	split_pmd_zero_pages();
 	split_pmd_thp();
 	split_pte_mapped_thp();
 	split_file_backed_thp();