Thanks for moving the functional tests. Some more feedback forksm_functional_tests change. Writing tests in the ksft testing framework can be a bit "special".
I'm seeing some weird test failures due to
prctl(PR_GET_MEMORY_MERGE, 0)
Apparently, these go away when using
prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0)
to explicitly force the other values to 0. Most probably, we should do that for PR_SET_MEMORY_MERGE as well (especially if we check for the arguments as well).
[...]
@@ -15,8 +15,10 @@ #include <errno.h> #include <fcntl.h> #include <sys/mman.h> +#include <sys/prctl.h> #include <sys/syscall.h> #include <sys/ioctl.h> +#include <sys/wait.h> #include <linux/userfaultfd.h> #include "../kselftest.h" @@ -326,9 +328,80 @@ static void test_unmerge_uffd_wp(void) } #endif +/* Verify that KSM can be enabled / queried with prctl. */ +static void test_ksm_prctl(void)
Maybe call this "test_prctl", because after all, these are all KSM tests.
+{
- bool ret = false;
- int is_on;
- int is_off;
- ksft_print_msg("[RUN] %s\n", __func__);
- if (prctl(PR_SET_MEMORY_MERGE, 1)) {
perror("prctl set");goto out;- }
- is_on = prctl(PR_GET_MEMORY_MERGE, 0);
- if (prctl(PR_SET_MEMORY_MERGE, 0)) {
perror("prctl set");goto out;- }
- is_off = prctl(PR_GET_MEMORY_MERGE, 0);
- if (is_on && is_off)
ret = true;+out:
- ksft_test_result(ret, "prctl get / set\n");
The test fails if the kernel does not support PR_SET_MEMORY_MERGE.
I'd modify this test to:
(1) skip if the first PR_SET_MEMORY_MERGE=1 failed with EINVAL. (2) distinguish for PR_GET_MEMORY_MERGE whether it returned an error or whether it returned a wrong value. Feel free to keep that as is, whatever you prefer. (3) exit early for all failures, you get exactly one expected skip/pass/fail for the test and use specific test failure messages. (4) Pass "0" for all other arguments of prctl.
Something like:
static void test_prctl(void) { int ret;
ksft_print_msg("[RUN] %s\n", __func__);
ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); if (ret < 0 && errno == EINVAL){ ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); return; } else if (ret) { ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); return; }
ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0); if (ret < 0) { ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n"); return; } else if (ret != 1) { ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 not effective\n"); return; }
ret = prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); if (ret){ ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); return; }
ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0); if (ret < 0) { ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n"); return; } else if (ret != 0) { ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 not effective\n"); return; }
ksft_test_result_pass("Setting/clearing PR_SET_MEMORY_MERGE works\n"); }
+}
+/* Verify that prctl ksm flag is inherited. */ +static void test_ksm_fork(void)
Maybe call it "test_prctl_fork"
+{
- int status;
- bool ret = false;
- pid_t child_pid;
- ksft_print_msg("[RUN] %s\n", __func__);
- if (prctl(PR_SET_MEMORY_MERGE, 1)) {
ksft_test_result_fail("prctl failed\n");goto out;- }
- child_pid = fork();
- if (child_pid == 0) {
int is_on =if (!is_on)exit(-1);exit(0);- }
- if (child_pid < 0) {
ksft_test_result_fail("child pid < 0\n");goto out;> +- if (waitpid(child_pid, &status, 0) < 0 || WEXITSTATUS(status) != 0) {
ksft_test_result_fail("wait pid < 0\n");goto out;- }
- if (prctl(PR_SET_MEMORY_MERGE, 0))
ksft_test_result_fail("prctl 2 failed\n");- else
ret = true;+out:
- ksft_test_result(ret, "ksm_flag is inherited\n");
+}
Again, test fails if kernel support is not around.
I'd modify this test to:
(1) skip if the first PR_SET_MEMORY_MERGE=1 failed with EINVAL just as in the other test. (2) Use a simple exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0)); in the child. (3) exit early for all failures, you get exactly one expected skip/pass/fail for the test and use specific test failure messages. (4) Split up the waitpid() check to test what failed. (5) Pass "0" for all other arguments of prctl.
Something like:
static void test_prctl_fork(void) { int ret, status; pid_t child_pid;
ksft_print_msg("[RUN] %s\n", __func__);
ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); if (ret < 0 && errno == EINVAL){ ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); return; } else if (ret) { ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); return; }
child_pid = fork(); if (!child_pid) { exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0)); } else if (child_pid < 0) { ksft_test_result_fail("fork() failed\n"); return; }
if (waitpid(child_pid, &status, 0) < 0) { ksft_test_result_fail("waitpid() failed\n"); return; } else if (WEXITSTATUS(status) != 1) { ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n"); return; }
if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) { ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); return; }
ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n"); }
- int main(int argc, char **argv) {
- unsigned int tests = 2;
- unsigned int tests = 6;
Assuming you execute exactly one ksft_test_result_skip/fail/pass on every path of your two test, this would become "4".
int err; #ifdef __NR_userfaultfd @@ -358,6 +431,8 @@ int main(int argc, char **argv) #ifdef __NR_userfaultfd test_unmerge_uffd_wp(); #endif
- test_ksm_prctl();
- test_ksm_fork();
With above outlined changes (feel free to integrate what you consider valuable), on an older kernel I get:
$ sudo ./ksm_functional_tests TAP version 13 1..5 # [RUN] test_unmerge ok 1 Pages were unmerged # [RUN] test_unmerge_discarded ok 2 Pages were unmerged # [RUN] test_unmerge_uffd_wp ok 3 Pages were unmerged # [RUN] test_prctl ok 4 # SKIP PR_SET_MEMORY_MERGE not supported # [RUN] test_prctl_fork ok 5 # SKIP PR_SET_MEMORY_MERGE not supported # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:2 error:0
On a kernel with your patch #1:
# ./ksm_functional_tests TAP version 13 1..5 # [RUN] test_unmerge ok 1 Pages were unmerged # [RUN] test_unmerge_discarded ok 2 Pages were unmerged # [RUN] test_unmerge_uffd_wp ok 3 Pages were unmerged # [RUN] test_prctl ok 4 Setting/clearing PR_SET_MEMORY_MERGE works # [RUN] test_prctl_fork ok 5 PR_SET_MEMORY_MERGE value is inherited # Totals: pass:5 fail:0 xfail:0 xpass:0 skip:0 error:0
err = ksft_get_fail_cnt(); if (err) diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c index f9eb4d67e0dd..35b3828d44b4 100644 --- a/tools/testing/selftests/mm/ksm_tests.c +++ b/tools/testing/selftests/mm/ksm_tests.c @@ -1,6 +1,8 @@ // SPDX-License-Identifier: GPL-2.0
[...]
Changes to ksm_tests mostly look good. Two comments:
- if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
- if (ksm_merge_pages(merge_type, 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);
if (merge_type == KSM_MERGE_MADVISE)munmap(map_ptr, page_size * page_count);else if (merge_type == KSM_MERGE_PRCTL)prctl(PR_SET_MEMORY_MERGE, 0);
Are you sure that we don't want to unmap here? I'd assume we want to unmap in either way.
[...]
case 'd':debug = 1;break;case 't':{int tmp = atoi(optarg);if (tmp < 0 || tmp > KSM_MERGE_LAST) {printf("Invalid merge type\n");return KSFT_FAIL;}merge_type = atoi(optarg);
You can simply reuse tmp
merge_type = tmp;