diff mbox series

[v2,2/2] mm/ksm: Test case for prctl fork/exec workflow

Message ID 20230920190117.784151-3-shr@devkernel.io (mailing list archive)
State New
Headers show
Series mm/ksm: add fork-exec support for prctl | expand

Commit Message

Stefan Roesch Sept. 20, 2023, 7:01 p.m. UTC 
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

David Hildenbrand Sept. 21, 2023, 11:44 a.m. UTC | #1 
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>
Stefan Roesch Sept. 21, 2023, 4:25 p.m. UTC | #2 
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>
diff mbox series

Patch

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;
+}
+
+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();