[PATCH v2 4/4] selftests: vm: add KSM merging across nodes test

[Zhansaya Bagdauletkyzy]

Add check_ksm_numa_merge() function  to test that pages in different NUMA
nodes are being handled properly. First, two duplicate pages are allocated
in two separate NUMA nodes using the libnuma library. Since there is one
unique page in each node, with merge_across_nodes = 0, there won't be any
shared pages. If merge_across_nodes is set to 1, the pages will be
treated as usual duplicate pages and will be merged. If NUMA config is
not enabled or the number of NUMA nodes is less than two, then the test
is skipped. The test is run as follows: ./ksm_tests -N

Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>
---
 tools/testing/selftests/vm/Makefile       |  2 +
 tools/testing/selftests/vm/ksm_tests.c    | 88 ++++++++++++++++++++++-
 tools/testing/selftests/vm/run_vmtests.sh | 32 +++++++++
 3 files changed, 119 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index e6f22a801b71..d9605bd10f2d 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -146,6 +146,8 @@ $(OUTPUT)/hmm-tests: local_config.h
 # HMM_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
 $(OUTPUT)/hmm-tests: LDLIBS += $(HMM_EXTRA_LIBS)
 
+$(OUTPUT)/ksm_tests: LDLIBS += -lnuma
+
 local_config.mk local_config.h: check_config.sh
 	/bin/sh ./check_config.sh $(CC)
 
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 5843526471e1..cdeb4a028538 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -4,6 +4,7 @@
 #include <stdbool.h>
 #include <time.h>
 #include <string.h>
+#include <numa.h>
 
 #include "../kselftest.h"
 
@@ -13,6 +14,7 @@
 #define KSM_PAGE_COUNT_DEFAULT 10l
 #define KSM_PROT_STR_DEFAULT "rw"
 #define KSM_USE_ZERO_PAGES_DEFAULT false
+#define KSM_MERGE_ACROSS_NODES_DEFAULT true
 
 struct ksm_sysfs {
 	unsigned long max_page_sharing;
@@ -27,7 +29,8 @@ struct ksm_sysfs {
 enum ksm_test_name {
 	CHECK_KSM_MERGE,
 	CHECK_KSM_UNMERGE,
-	CHECK_KSM_ZERO_PAGE_MERGE
+	CHECK_KSM_ZERO_PAGE_MERGE,
+	CHECK_KSM_NUMA_MERGE
 };
 
 static int ksm_write_sysfs(const char *file_path, unsigned long val)
@@ -83,11 +86,12 @@ static int str_to_prot(char *prot_str)
 static void print_help(void)
 {
 	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
-	       "[-z use_zero_pages]\n");
+	       "[-z use_zero_pages] [-m merge_across_nodes]\n");
 
 	printf("Supported <test type>:\n"
 	       " -M (page merging)\n"
 	       " -Z (zero pages merging)\n"
+	       " -N (merging of pages in different NUMA nodes)\n"
 	       " -U (page unmerging)\n\n");
 
 	printf(" -a: specify the access protections of pages.\n"
@@ -99,6 +103,8 @@ static void print_help(void)
 	       "     Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
 	printf(" -z: change use_zero_pages tunable\n"
 	       "     Default: %d\n", KSM_USE_ZERO_PAGES_DEFAULT);
+	printf(" -m: change merge_across_nodes tunable\n"
+	       "     Default: %d\n", KSM_MERGE_ACROSS_NODES_DEFAULT);
 
 	exit(0);
 }
@@ -339,6 +345,68 @@ static int check_ksm_zero_page_merge(int mapping, int prot, long page_count, int
 	return KSFT_FAIL;
 }
 
+static int check_ksm_numa_merge(int mapping, int prot, int timeout, bool merge_across_nodes,
+				size_t page_size)
+{
+	void *numa1_map_ptr, *numa2_map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	if (numa_available() < 0) {
+		perror("NUMA support not enabled");
+		return KSFT_SKIP;
+	}
+	if (numa_max_node() < 1) {
+		printf("At least 2 NUMA nodes must be available\n");
+		return KSFT_SKIP;
+	}
+	if (ksm_write_sysfs(KSM_FP("merge_across_nodes"), merge_across_nodes))
+		return KSFT_FAIL;
+
+	/* allocate 2 pages in 2 different NUMA nodes and fill them with the same data */
+	numa1_map_ptr = numa_alloc_onnode(page_size, 0);
+	numa2_map_ptr = numa_alloc_onnode(page_size, 1);
+	if (!numa1_map_ptr || !numa2_map_ptr) {
+		perror("numa_alloc_onnode");
+		return KSFT_FAIL;
+	}
+
+	memset(numa1_map_ptr, '*', page_size);
+	memset(numa2_map_ptr, '*', page_size);
+
+	/* try to merge the pages */
+	if (ksm_merge_pages(numa1_map_ptr, page_size, start_time, timeout) ||
+	    ksm_merge_pages(numa2_map_ptr, page_size, start_time, timeout))
+		goto err_out;
+
+       /*
+	* verify that the right number of pages are merged:
+	* 1) if merge_across_nodes was enabled, 2 duplicate pages will be merged;
+	* 2) if merge_across_nodes = 0, there must be 0 merged pages, since there is
+	*    only 1 unique page in each node and they can't be shared.
+	*/
+	if (merge_across_nodes && !assert_ksm_pages_count(page_count))
+		goto err_out;
+	else if (!merge_across_nodes && !assert_ksm_pages_count(0))
+		goto err_out;
+
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("OK\n");
+	return KSFT_PASS;
+
+err_out:
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("Not OK\n");
+	return KSFT_FAIL;
+}
+
 int main(int argc, char *argv[])
 {
 	int ret, opt;
@@ -349,8 +417,9 @@ int main(int argc, char *argv[])
 	struct ksm_sysfs ksm_sysfs_old;
 	int test_name = CHECK_KSM_MERGE;
 	bool use_zero_pages = KSM_USE_ZERO_PAGES_DEFAULT;
+	bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
 
-	while ((opt = getopt(argc, argv, "ha:p:l:z:MUZ")) != -1) {
+	while ((opt = getopt(argc, argv, "ha:p:l:z:m:MUZN")) != -1) {
 		switch (opt) {
 		case 'a':
 			prot = str_to_prot(optarg);
@@ -378,6 +447,12 @@ int main(int argc, char *argv[])
 			else
 				use_zero_pages = 1;
 			break;
+		case 'm':
+			if (strcmp(optarg, "0") == 0)
+				merge_across_nodes = 0;
+			else
+				merge_across_nodes = 1;
+			break;
 		case 'M':
 			break;
 		case 'U':
@@ -386,6 +461,9 @@ int main(int argc, char *argv[])
 		case 'Z':
 			test_name = CHECK_KSM_ZERO_PAGE_MERGE;
 			break;
+		case 'N':
+			test_name = CHECK_KSM_NUMA_MERGE;
+			break;
 		default:
 			return KSFT_FAIL;
 		}
@@ -423,6 +501,10 @@ int main(int argc, char *argv[])
 		ret = check_ksm_zero_page_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
 						ksm_scan_limit_sec, use_zero_pages, page_size);
 		break;
+	case CHECK_KSM_NUMA_MERGE:
+		ret = check_ksm_numa_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+					   merge_across_nodes, page_size);
+		break;
 	}
 
 	if (ksm_restore(&ksm_sysfs_old)) {
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index 9b4e444fc4ed..45e803af7c77 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -441,6 +441,38 @@ else
 	exitcode=1
 fi
 
+echo "-------------------------------------------------------------"
+echo "running KSM test with 2 NUMA nodes and merge_across_nodes = 1"
+echo "-------------------------------------------------------------"
+./ksm_tests -N -m 1
+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 test with 2 NUMA nodes and merge_across_nodes = 0"
+echo "-------------------------------------------------------------"
+./ksm_tests -N -m 0
+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
+
 exit $exitcode
 
 exit $exitcode
-- 
2.25.1