1 files changed, 48 insertions, 1 deletions

diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index db0270127aeb..9496346973d4 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -119,6 +119,50 @@ static unsigned long long get_mmap_min_addr(void)
 }
 
 /*
+ * This test validates that merge is called when expanding a mapping.
+ * Mapping containing three pages is created, middle page is unmapped
+ * and then the mapping containing the first page is expanded so that
+ * it fills the created hole. The two parts should merge creating
+ * single mapping with three pages.
+ */
+static void mremap_expand_merge(unsigned long page_size)
+{
+	char *test_name = "mremap expand merge";
+	FILE *fp;
+	char *line = NULL;
+	size_t len = 0;
+	bool success = false;
+	char *start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	munmap(start + page_size, page_size);
+	mremap(start, page_size, 2 * page_size, 0);
+
+	fp = fopen("/proc/self/maps", "r");
+	if (fp == NULL) {
+		ksft_test_result_fail("%s\n", test_name);
+		return;
+	}
+
+	while (getline(&line, &len, fp) != -1) {
+		char *first = strtok(line, "- ");
+		void *first_val = (void *)strtol(first, NULL, 16);
+		char *second = strtok(NULL, "- ");
+		void *second_val = (void *) strtol(second, NULL, 16);
+
+		if (first_val == start && second_val == start + 3 * page_size) {
+			success = true;
+			break;
+		}
+	}
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+	fclose(fp);
+}
+
+/*
  * Returns the start address of the mapping on success, else returns
  * NULL on failure.
  */
@@ -336,6 +380,7 @@ int main(int argc, char **argv)
 	int i, run_perf_tests;
 	unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
 	unsigned int pattern_seed;
+	int num_expand_tests = 1;
 	struct test test_cases[MAX_TEST];
 	struct test perf_test_cases[MAX_PERF_TEST];
 	int page_size;
@@ -407,12 +452,14 @@ int main(int argc, char **argv)
 				(threshold_mb * _1MB >= _1GB);
 
 	ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ?
-		      ARRAY_SIZE(perf_test_cases) : 0));
+		      ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests);
 
 	for (i = 0; i < ARRAY_SIZE(test_cases); i++)
 		run_mremap_test_case(test_cases[i], &failures, threshold_mb,
 				     pattern_seed);
 
+	mremap_expand_merge(page_size);
+
 	if (run_perf_tests) {
 		ksft_print_msg("\n%s\n",
 		 "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");