On 2021-07-14 14:56:09, Zhansaya Bagdauletkyzy wrote:
> Add check_ksm_unmerge() function to verify that KSM is properly
> unmerging shared pages. For this, two duplicate pages are merged first
> and then their contents are modified. Since they are not identical
> anymore, the pages must be unmerged and the number of merged pages has
> to be 0. The test is run as follows: ./ksm_tests -U
>
> Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@xxxxxxxxx>
Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
Tyler
> ---
> tools/testing/selftests/vm/ksm_tests.c | 72 +++++++++++++++++++++--
> tools/testing/selftests/vm/run_vmtests.sh | 18 +++++-
> 2 files changed, 85 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
> index d74d5aa34b16..80302bb8f64c 100644
> --- a/tools/testing/selftests/vm/ksm_tests.c
> +++ b/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 @@ static int check_ksm_merge(int mapping, int prot, long page_count, int timeout,
> 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");
> diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
> index 97b6f712134d..3a23c6b47da2 100755
> --- a/tools/testing/selftests/vm/run_vmtests.sh
> +++ b/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
> --
> 2.25.1
>
