Add check_ksm_merge() function to check the basic merging feature of
KSM. First, some number of identical pages are allocated and the
MADV_MERGEABLE advice is given to merge these pages. Then, pages_shared
and pages_sharing values are compared with the expected numbers using
assert_ksm_pages_count() function. The number of pages can be changed
using -p option.
Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>
---
tools/testing/selftests/vm/.gitignore | 1 +
tools/testing/selftests/vm/Makefile | 1 +
tools/testing/selftests/vm/ksm_tests.c | 306 ++++++++++++++++++++++
tools/testing/selftests/vm/run_vmtests.sh | 16 ++
4 files changed, 324 insertions(+)
create mode 100644 tools/testing/selftests/vm/ksm_tests.c
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
index f0fd80ef17df..b02eac613fdd 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/vm/.gitignore
@@ -27,3 +27,4 @@ hmm-tests
memfd_secret
local_config.*
split_huge_page_test
+ksm_tests
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index 521243770f26..e6f22a801b71 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -45,6 +45,7 @@ TEST_GEN_FILES += thuge-gen
TEST_GEN_FILES += transhuge-stress
TEST_GEN_FILES += userfaultfd
TEST_GEN_FILES += split_huge_page_test
+TEST_GEN_FILES += ksm_tests
ifeq ($(MACHINE),x86_64)
CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh $(CC) ../x86/trivial_32bit_program.c -m32)
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
new file mode 100644
index 000000000000..d74d5aa34b16
--- /dev/null
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/mman.h>
+#include <stdbool.h>
+#include <time.h>
+#include <string.h>
+
+#include "../kselftest.h"
+
+#define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
+#define KSM_FP(s) (KSM_SYSFS_PATH s)
+#define KSM_SCAN_LIMIT_SEC_DEFAULT 120
+#define KSM_PAGE_COUNT_DEFAULT 10l
+#define KSM_PROT_STR_DEFAULT "rw"
+
+struct ksm_sysfs {
+ unsigned long max_page_sharing;
+ unsigned long merge_across_nodes;
+ unsigned long pages_to_scan;
+ unsigned long run;
+ unsigned long sleep_millisecs;
+ unsigned long stable_node_chains_prune_millisecs;
+ unsigned long use_zero_pages;
+};
+
+static int ksm_write_sysfs(const char *file_path, unsigned long val)
+{
+ FILE *f = fopen(file_path, "w");
+
+ if (!f) {
+ fprintf(stderr, "f %s\n", file_path);
+ perror("fopen");
+ return 1;
+ }
+ if (fprintf(f, "%lu", val) < 0) {
+ perror("fprintf");
+ return 1;
+ }
+ fclose(f);
+
+ return 0;
+}
+
+static int ksm_read_sysfs(const char *file_path, unsigned long *val)
+{
+ FILE *f = fopen(file_path, "r");
+
+ if (!f) {
+ fprintf(stderr, "f %s\n", file_path);
+ perror("fopen");
+ return 1;
+ }
+ if (fscanf(f, "%lu", val) != 1) {
+ perror("fscanf");
+ return 1;
+ }
+ fclose(f);
+
+ return 0;
+}
+
+static int str_to_prot(char *prot_str)
+{
+ int prot = 0;
+
+ if ((strchr(prot_str, 'r')) != NULL)
+ prot |= PROT_READ;
+ if ((strchr(prot_str, 'w')) != NULL)
+ prot |= PROT_WRITE;
+ if ((strchr(prot_str, 'x')) != NULL)
+ prot |= PROT_EXEC;
+
+ return prot;
+}
+
+static void print_help(void)
+{
+ printf("usage: ksm_tests [-h] [-a prot] [-p page_count] [-l timeout]\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);
+ printf(" -p: specify the number of pages to test.\n"
+ " Default: %ld\n", KSM_PAGE_COUNT_DEFAULT);
+ printf(" -l: limit the maximum running time (in seconds) for a test.\n"
+ " Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
+
+ exit(0);
+}
+
+static void *allocate_memory(void *ptr, int prot, int mapping, char data, size_t map_size)
+{
+ void *map_ptr = mmap(ptr, map_size, PROT_WRITE, mapping, -1, 0);
+
+ if (!map_ptr) {
+ perror("mmap");
+ return NULL;
+ }
+ memset(map_ptr, data, map_size);
+ if (mprotect(map_ptr, map_size, prot)) {
+ perror("mprotect");
+ munmap(map_ptr, map_size);
+ return NULL;
+ }
+
+ return map_ptr;
+}
+
+static int ksm_do_scan(int scan_count, struct timespec start_time, int timeout)
+{
+ struct timespec cur_time;
+ unsigned long cur_scan, init_scan;
+
+ if (ksm_read_sysfs(KSM_FP("full_scans"), &init_scan))
+ return 1;
+ cur_scan = init_scan;
+
+ while (cur_scan < init_scan + scan_count) {
+ if (ksm_read_sysfs(KSM_FP("full_scans"), &cur_scan))
+ return 1;
+ if (clock_gettime(CLOCK_MONOTONIC_RAW, &cur_time)) {
+ perror("clock_gettime");
+ return 1;
+ }
+ if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
+ printf("Scan time limit exceeded\n");
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static int ksm_merge_pages(void *addr, size_t size, struct timespec start_time, int timeout)
+{
+ if (madvise(addr, size, MADV_MERGEABLE)) {
+ perror("madvise");
+ return 1;
+ }
+ if (ksm_write_sysfs(KSM_FP("run"), 1))
+ return 1;
+
+ /* Since merging occurs only after 2 scans, make sure to get at least 2 full scans */
+ if (ksm_do_scan(2, start_time, timeout))
+ return 1;
+
+ return 0;
+}
+
+static bool assert_ksm_pages_count(long dupl_page_count)
+{
+ unsigned long max_page_sharing, pages_sharing, pages_shared;
+
+ if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
+ ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
+ ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing))
+ return false;
+
+ /*
+ * Since there must be at least 2 pages for merging and 1 page can be
+ * shared with the limited number of pages (max_page_sharing), sometimes
+ * there are 'leftover' pages that cannot be merged. For example, if there
+ * are 11 pages and max_page_sharing = 10, then only 10 pages will be
+ * merged and the 11th page won't be affected. As a result, when the number
+ * of duplicate pages is divided by max_page_sharing and the remainder is 1,
+ * pages_shared and pages_sharing values will be equal between dupl_page_count
+ * and dupl_page_count - 1.
+ */
+ if (dupl_page_count % max_page_sharing == 1 || dupl_page_count % max_page_sharing == 0) {
+ if (pages_shared == dupl_page_count / max_page_sharing &&
+ pages_sharing == pages_shared * (max_page_sharing - 1))
+ return true;
+ } else {
+ if (pages_shared == (dupl_page_count / max_page_sharing + 1) &&
+ pages_sharing == dupl_page_count - pages_shared)
+ return true;
+ }
+
+ return false;
+}
+
+static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
+{
+ if (ksm_read_sysfs(KSM_FP("max_page_sharing"), &ksm_sysfs->max_page_sharing) ||
+ ksm_read_sysfs(KSM_FP("merge_across_nodes"), &ksm_sysfs->merge_across_nodes) ||
+ ksm_read_sysfs(KSM_FP("sleep_millisecs"), &ksm_sysfs->sleep_millisecs) ||
+ ksm_read_sysfs(KSM_FP("pages_to_scan"), &ksm_sysfs->pages_to_scan) ||
+ ksm_read_sysfs(KSM_FP("run"), &ksm_sysfs->run) ||
+ ksm_read_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+ &ksm_sysfs->stable_node_chains_prune_millisecs) ||
+ ksm_read_sysfs(KSM_FP("use_zero_pages"), &ksm_sysfs->use_zero_pages))
+ return 1;
+
+ return 0;
+}
+
+static int ksm_restore(struct ksm_sysfs *ksm_sysfs)
+{
+ if (ksm_write_sysfs(KSM_FP("max_page_sharing"), ksm_sysfs->max_page_sharing) ||
+ ksm_write_sysfs(KSM_FP("merge_across_nodes"), ksm_sysfs->merge_across_nodes) ||
+ ksm_write_sysfs(KSM_FP("pages_to_scan"), ksm_sysfs->pages_to_scan) ||
+ ksm_write_sysfs(KSM_FP("run"), ksm_sysfs->run) ||
+ ksm_write_sysfs(KSM_FP("sleep_millisecs"), ksm_sysfs->sleep_millisecs) ||
+ ksm_write_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+ ksm_sysfs->stable_node_chains_prune_millisecs) ||
+ ksm_write_sysfs(KSM_FP("use_zero_pages"), ksm_sysfs->use_zero_pages))
+ return 1;
+
+ return 0;
+}
+
+static int check_ksm_merge(int mapping, int prot, long page_count, int timeout, size_t page_size)
+{
+ void *map_ptr;
+ struct timespec start_time;
+
+ 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;
+
+ /* verify that the right number of pages are merged */
+ if (assert_ksm_pages_count(page_count)) {
+ 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;
+ int prot = 0;
+ int ksm_scan_limit_sec = KSM_SCAN_LIMIT_SEC_DEFAULT;
+ long page_count = KSM_PAGE_COUNT_DEFAULT;
+ size_t page_size = sysconf(_SC_PAGESIZE);
+ struct ksm_sysfs ksm_sysfs_old;
+
+ while ((opt = getopt(argc, argv, "ha:p:l:")) != -1) {
+ switch (opt) {
+ case 'a':
+ prot = str_to_prot(optarg);
+ break;
+ case 'p':
+ page_count = atol(optarg);
+ if (page_count <= 0) {
+ printf("The number of pages must be greater than 0\n");
+ return KSFT_FAIL;
+ }
+ break;
+ case 'l':
+ ksm_scan_limit_sec = atoi(optarg);
+ if (ksm_scan_limit_sec <= 0) {
+ printf("Timeout value must be greater than 0\n");
+ return KSFT_FAIL;
+ }
+ break;
+ case 'h':
+ print_help();
+ break;
+ default:
+ return KSFT_FAIL;
+ }
+ }
+
+ if (prot == 0)
+ prot = str_to_prot(KSM_PROT_STR_DEFAULT);
+
+ if (access(KSM_SYSFS_PATH, F_OK)) {
+ printf("Config KSM not enabled\n");
+ return KSFT_SKIP;
+ }
+
+ if (ksm_save_def(&ksm_sysfs_old)) {
+ printf("Cannot save default tunables\n");
+ return KSFT_FAIL;
+ }
+
+ if (ksm_write_sysfs(KSM_FP("run"), 2) ||
+ ksm_write_sysfs(KSM_FP("sleep_millisecs"), 0) ||
+ ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1) ||
+ 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);
+
+ if (ksm_restore(&ksm_sysfs_old)) {
+ printf("Cannot restore default tunables\n");
+ return KSFT_FAIL;
+ }
+
+ return ret;
+}
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index d09a6b71f1e9..97b6f712134d 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -377,6 +377,22 @@ else
exitcode=1
fi
+echo "-------------------------------------------------------"
+echo "running KSM MADV_MERGEABLE test with 10 identical pages"
+echo "-------------------------------------------------------"
+./ksm_tests -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
+
exit $exitcode
exit $exitcode
--
2.25.1
