[v2,2/2] mm/ksm: Test case for prctl fork/exec workflow
Commit Message
This adds a new test case to the ksm functional tests to make sure that
the KSM setting is inherited by the child process when doing a
fork/exec.
Signed-off-by: Stefan Roesch <shr@devkernel.io>
---
.../selftests/mm/ksm_functional_tests.c | 67 ++++++++++++++++++-
1 file changed, 66 insertions(+), 1 deletion(-)
Comments
On 20.09.23 21:01, Stefan Roesch wrote:
> This adds a new test case to the ksm functional tests to make sure that
> the KSM setting is inherited by the child process when doing a
> fork/exec.
>
> Signed-off-by: Stefan Roesch <shr@devkernel.io>
> ---
> .../selftests/mm/ksm_functional_tests.c | 67 ++++++++++++++++++-
> 1 file changed, 66 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
> index 901e950f9138..40b86c9caf3a 100644
> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
> @@ -26,6 +26,7 @@
>
> #define KiB 1024u
> #define MiB (1024 * KiB)
> +#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child"
>
> static int mem_fd;
> static int ksm_fd;
> @@ -479,6 +480,65 @@ static void test_prctl_fork(void)
> ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
> }
>
> +static int ksm_fork_exec_child(void)
> +{
> + /* Test if KSM is enabled for the process. */
> + int ksm = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
> + return ksm == 1;
You can simply do "return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 1;"
Or maybe even "return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);" and
adjust the comparison below in the caller.
> +}
> +
> +static void test_prctl_fork_exec(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 == -1) {
> + ksft_test_result_skip("fork() failed\n");
> + return;
> + } else if (child_pid == 0) {
> + char *prg_name = "./ksm_functional_tests";
> + char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME };
> +
I'd simply have used the magic number "1" or so. But this works as well.
Reviewed-by: David Hildenbrand <david@redhat.com>
David Hildenbrand <david@redhat.com> writes:
> On 20.09.23 21:01, Stefan Roesch wrote:
>> This adds a new test case to the ksm functional tests to make sure that
>> the KSM setting is inherited by the child process when doing a
>> fork/exec.
>> Signed-off-by: Stefan Roesch <shr@devkernel.io>
>> ---
>> .../selftests/mm/ksm_functional_tests.c | 67 ++++++++++++++++++-
>> 1 file changed, 66 insertions(+), 1 deletion(-)
>> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c
>> b/tools/testing/selftests/mm/ksm_functional_tests.c
>> index 901e950f9138..40b86c9caf3a 100644
>> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
>> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
>> @@ -26,6 +26,7 @@
>> #define KiB 1024u
>> #define MiB (1024 * KiB)
>> +#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child"
>> static int mem_fd;
>> static int ksm_fd;
>> @@ -479,6 +480,65 @@ static void test_prctl_fork(void)
>> ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
>> }
>> +static int ksm_fork_exec_child(void)
>> +{
>> + /* Test if KSM is enabled for the process. */
>> + int ksm = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
>> + return ksm == 1;
>
> You can simply do "return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 1;"
>
> Or maybe even "return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);" and adjust the
> comparison below in the caller.
>
I'll use the first one, then its all in one place.
>> +}
>> +
>> +static void test_prctl_fork_exec(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 == -1) {
>> + ksft_test_result_skip("fork() failed\n");
>> + return;
>> + } else if (child_pid == 0) {
>> + char *prg_name = "./ksm_functional_tests";
>> + char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME };
>> +
>
> I'd simply have used the magic number "1" or so. But this works as well.
>
I think the current one makes it easier in case we have to add a second
one later.
> Reviewed-by: David Hildenbrand <david@redhat.com>
@@ -26,6 +26,7 @@
#define KiB 1024u
#define MiB (1024 * KiB)
+#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child"
static int mem_fd;
static int ksm_fd;
@@ -479,6 +480,65 @@ static void test_prctl_fork(void)
ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
}
+static int ksm_fork_exec_child(void)
+{
+ /* Test if KSM is enabled for the process. */
+ int ksm = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
+ return ksm == 1;
+}
+
+static void test_prctl_fork_exec(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 == -1) {
+ ksft_test_result_skip("fork() failed\n");
+ return;
+ } else if (child_pid == 0) {
+ char *prg_name = "./ksm_functional_tests";
+ char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME };
+
+ execv(prg_name, argv_for_program);
+ return;
+ }
+
+ if (waitpid(child_pid, &status, 0) > 0) {
+ if (WIFEXITED(status)) {
+ status = WEXITSTATUS(status);
+ if (status) {
+ ksft_test_result_fail("KSM not enabled\n");
+ return;
+ }
+ } else {
+ ksft_test_result_fail("program didn't terminate normally\n");
+ return;
+ }
+ } else {
+ ksft_test_result_fail("waitpid() failed\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");
+}
+
static void test_prctl_unmerge(void)
{
const unsigned int size = 2 * MiB;
@@ -536,9 +596,13 @@ static void test_prot_none(void)
int main(int argc, char **argv)
{
- unsigned int tests = 7;
+ unsigned int tests = 8;
int err;
+ if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
+ exit(ksm_fork_exec_child() == 1 ? 0 : 1);
+ }
+
#ifdef __NR_userfaultfd
tests++;
#endif
@@ -576,6 +640,7 @@ int main(int argc, char **argv)
test_prctl();
test_prctl_fork();
+ test_prctl_fork_exec();
test_prctl_unmerge();
err = ksft_get_fail_cnt();