--- a/tools/testing/selftests/vm/ksm_tests.c~selftests-vm-add-ksm-unmerge-test
+++ a/tools/testing/selftests/vm/ksm_tests.c
@@ -23,6 +23,11 @@ struct ksm_sysfs {
 	unsigned long use_zero_pages;
 };
 
+enum ksm_test_name {
+	CHECK_KSM_MERGE,
+	CHECK_KSM_UNMERGE
+};
+
 static int ksm_write_sysfs(const char *file_path, unsigned long val)
 {
 	FILE *f = fopen(file_path, "w");
@@ -75,7 +80,12 @@ static int str_to_prot(char *prot_str)
 
 static void print_help(void)
 {
-	printf("usage: ksm_tests [-h] [-a prot] [-p page_count] [-l timeout]\n");
+	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n");
+
+	printf("Supported <test type>:\n"
+	       " -M (page merging)\n"
+	       " -U (page unmerging)\n\n");
+
 	printf(" -a: specify the access protections of pages.\n"
 	       "     <prot> must be of the form [rwx].\n"
 	       "     Default: %s\n", KSM_PROT_STR_DEFAULT);
@@ -239,6 +249,46 @@ err_out:
 	return KSFT_FAIL;
 }
 
+static int check_ksm_unmerge(int mapping, int prot, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	/* fill pages with the same data and merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	/* change 1 byte in each of the 2 pages -- KSM must automatically unmerge them */
+	memset(map_ptr, '-', 1);
+	memset(map_ptr + page_size, '+', 1);
+
+	/* get at least 1 scan, so KSM can detect that the pages were modified */
+	if (ksm_do_scan(1, start_time, timeout))
+		goto err_out;
+
+	/* check that unmerging was successful and 0 pages are currently merged */
+	if (assert_ksm_pages_count(0)) {
+		printf("OK\n");
+		munmap(map_ptr, page_size * page_count);
+		return KSFT_PASS;
+	}
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
 int main(int argc, char *argv[])
 {
 	int ret, opt;
@@ -247,8 +297,9 @@ int main(int argc, char *argv[])
 	long page_count = KSM_PAGE_COUNT_DEFAULT;
 	size_t page_size = sysconf(_SC_PAGESIZE);
 	struct ksm_sysfs ksm_sysfs_old;
+	int test_name = CHECK_KSM_MERGE;
 
-	while ((opt = getopt(argc, argv, "ha:p:l:")) != -1) {
+	while ((opt = getopt(argc, argv, "ha:p:l:MU")) != -1) {
 		switch (opt) {
 		case 'a':
 			prot = str_to_prot(optarg);
@@ -270,6 +321,11 @@ int main(int argc, char *argv[])
 		case 'h':
 			print_help();
 			break;
+		case 'M':
+			break;
+		case 'U':
+			test_name = CHECK_KSM_UNMERGE;
+			break;
 		default:
 			return KSFT_FAIL;
 		}
@@ -294,8 +350,16 @@ int main(int argc, char *argv[])
 	    ksm_write_sysfs(KSM_FP("pages_to_scan"), page_count))
 		return KSFT_FAIL;
 
-	ret = check_ksm_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count, ksm_scan_limit_sec,
-			      page_size);
+	switch (test_name) {
+	case CHECK_KSM_MERGE:
+		ret = check_ksm_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
+				      ksm_scan_limit_sec, page_size);
+		break;
+	case CHECK_KSM_UNMERGE:
+		ret = check_ksm_unmerge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+					page_size);
+		break;
+	}
 
 	if (ksm_restore(&ksm_sysfs_old)) {
 		printf("Cannot restore default tunables\n");
--- a/tools/testing/selftests/vm/run_vmtests.sh~selftests-vm-add-ksm-unmerge-test
+++ a/tools/testing/selftests/vm/run_vmtests.sh
@@ -380,7 +380,23 @@ fi
 echo "-------------------------------------------------------"
 echo "running KSM MADV_MERGEABLE test with 10 identical pages"
 echo "-------------------------------------------------------"
-./ksm_tests -p 10
+./ksm_tests -M -p 10
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+	echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+	 echo "[SKIP]"
+	 exitcode=$ksft_skip
+else
+	echo "[FAIL]"
+	exitcode=1
+fi
+
+echo "------------------------"
+echo "running KSM unmerge test"
+echo "------------------------"
+./ksm_tests -U
 ret_val=$?
 
 if [ $ret_val -eq 0 ]; then
