diff mbox series

[v1,2/2] mm/ksm: Test case for prctl fork/exec workflow

Message ID 20230919205158.1897353-3-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. 19, 2023, 8:51 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>
---
 tools/testing/selftests/mm/Makefile           |  2 +
 .../selftests/mm/ksm_fork_exec_child.c        |  9 ++++
 .../selftests/mm/ksm_functional_tests.c       | 50 ++++++++++++++++++-
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/mm/ksm_fork_exec_child.c

Comments

David Hildenbrand Sept. 20, 2023, 1:16 p.m. UTC | #1
On 19.09.23 22:51, 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>
> ---
>   tools/testing/selftests/mm/Makefile           |  2 +
>   .../selftests/mm/ksm_fork_exec_child.c        |  9 ++++
>   .../selftests/mm/ksm_functional_tests.c       | 50 ++++++++++++++++++-
>   3 files changed, 60 insertions(+), 1 deletion(-)
>   create mode 100644 tools/testing/selftests/mm/ksm_fork_exec_child.c
> 
> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
> index 6a9fc5693145..9ab6aa402544 100644
> --- a/tools/testing/selftests/mm/Makefile
> +++ b/tools/testing/selftests/mm/Makefile
> @@ -73,6 +73,8 @@ ifneq ($(ARCH),arm64)
>   TEST_GEN_PROGS += soft-dirty
>   endif
>   
> +TEST_GEN_PROGS += ksm_fork_exec_child

It's not a test itself, so it shouldn't be run when running all tests. 
See below.

> +
>   ifeq ($(ARCH),x86_64)
>   CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
>   CAN_BUILD_X86_64 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_64bit_program.c)
> diff --git a/tools/testing/selftests/mm/ksm_fork_exec_child.c b/tools/testing/selftests/mm/ksm_fork_exec_child.c
> new file mode 100644
> index 000000000000..298439f0d55f
> --- /dev/null
> +++ b/tools/testing/selftests/mm/ksm_fork_exec_child.c
> @@ -0,0 +1,9 @@
> +#include <sys/prctl.h>
> +#include <stdlib.h>
> +
> +int main()
> +{
> +	/* Test if KSM is enabled for the process. */
> +	int ksm = prctl(68, 0, 0, 0, 0);

Can we use the define from a header? (PR_SET_MEMORY_MERGE)

I was wondering if we could simply exec() ourself (same binary), but 
pass a special cmdline argument. Then you don't have to build a separate 
binary.

Just special-case in main() on that argument and perform this check.

> +	exit(ksm == 1 ? 0 : 1);
> +}
> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
> index 901e950f9138..4dc0bb522c07 100644
> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
> @@ -479,6 +479,53 @@ static void test_prctl_fork(void)
>   	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
>   }
>   
> +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 *filename = "./ksm_fork_exec_child";
> +		char *argv_for_program[] = { filename, NULL };
> +
> +		execv(filename, argv_for_program);;

s/;;/;/

Add a return; so you can simplify the code below (no need for the "else")

> +	} else {
> +		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;
> +		}
> +	}
> +
> +	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");

It's probably the cleanest to disable PR_SET_MEMORY_MERGE again when 
returning form this function, so the other tests have a clean slate.
Stefan Roesch Sept. 20, 2023, 6:57 p.m. UTC | #2
David Hildenbrand <david@redhat.com> writes:

> On 19.09.23 22:51, 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>
>> ---
>>   tools/testing/selftests/mm/Makefile           |  2 +
>>   .../selftests/mm/ksm_fork_exec_child.c        |  9 ++++
>>   .../selftests/mm/ksm_functional_tests.c       | 50 ++++++++++++++++++-
>>   3 files changed, 60 insertions(+), 1 deletion(-)
>>   create mode 100644 tools/testing/selftests/mm/ksm_fork_exec_child.c
>> diff --git a/tools/testing/selftests/mm/Makefile
>> b/tools/testing/selftests/mm/Makefile
>> index 6a9fc5693145..9ab6aa402544 100644
>> --- a/tools/testing/selftests/mm/Makefile
>> +++ b/tools/testing/selftests/mm/Makefile
>> @@ -73,6 +73,8 @@ ifneq ($(ARCH),arm64)
>>   TEST_GEN_PROGS += soft-dirty
>>   endif
>>   +TEST_GEN_PROGS += ksm_fork_exec_child
>
> It's not a test itself, so it shouldn't be run when running all tests. See
> below.
>
>> +
>>   ifeq ($(ARCH),x86_64)
>>   CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
>>   CAN_BUILD_X86_64 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_64bit_program.c)
>> diff --git a/tools/testing/selftests/mm/ksm_fork_exec_child.c b/tools/testing/selftests/mm/ksm_fork_exec_child.c
>> new file mode 100644
>> index 000000000000..298439f0d55f
>> --- /dev/null
>> +++ b/tools/testing/selftests/mm/ksm_fork_exec_child.c
>> @@ -0,0 +1,9 @@
>> +#include <sys/prctl.h>
>> +#include <stdlib.h>
>> +
>> +int main()
>> +{
>> +	/* Test if KSM is enabled for the process. */
>> +	int ksm = prctl(68, 0, 0, 0, 0);
>
> Can we use the define from a header? (PR_SET_MEMORY_MERGE)
>

I changed it.

> I was wondering if we could simply exec() ourself (same binary), but pass a
> special cmdline argument. Then you don't have to build a separate binary.
>

I'm execing the same executable with an additional parameter.

> Just special-case in main() on that argument and perform this check.
>

I added a check in main and invoke a new function for the child.

>> +	exit(ksm == 1 ? 0 : 1);
>> +}
>> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
>> index 901e950f9138..4dc0bb522c07 100644
>> --- a/tools/testing/selftests/mm/ksm_functional_tests.c
>> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c
>> @@ -479,6 +479,53 @@ static void test_prctl_fork(void)
>>   	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
>>   }
>>   +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 *filename = "./ksm_fork_exec_child";
>> +		char *argv_for_program[] = { filename, NULL };
>> +
>> +		execv(filename, argv_for_program);;
>
> s/;;/;/
>

Fixed.

> Add a return; so you can simplify the code below (no need for the "else")
>

Done.


>> +	} else {
>> +		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;
>> +		}
>> +	}
>> +
>> +	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
>
> It's probably the cleanest to disable PR_SET_MEMORY_MERGE again when returning
> form this function, so the other tests have a clean slate.

In the next version it is disabled at the end.
diff mbox series

Patch

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 6a9fc5693145..9ab6aa402544 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -73,6 +73,8 @@  ifneq ($(ARCH),arm64)
 TEST_GEN_PROGS += soft-dirty
 endif
 
+TEST_GEN_PROGS += ksm_fork_exec_child
+
 ifeq ($(ARCH),x86_64)
 CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
 CAN_BUILD_X86_64 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_64bit_program.c)
diff --git a/tools/testing/selftests/mm/ksm_fork_exec_child.c b/tools/testing/selftests/mm/ksm_fork_exec_child.c
new file mode 100644
index 000000000000..298439f0d55f
--- /dev/null
+++ b/tools/testing/selftests/mm/ksm_fork_exec_child.c
@@ -0,0 +1,9 @@ 
+#include <sys/prctl.h>
+#include <stdlib.h>
+
+int main()
+{
+	/* Test if KSM is enabled for the process. */
+	int ksm = prctl(68, 0, 0, 0, 0);
+	exit(ksm == 1 ? 0 : 1);
+}
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index 901e950f9138..4dc0bb522c07 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -479,6 +479,53 @@  static void test_prctl_fork(void)
 	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
 }
 
+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 *filename = "./ksm_fork_exec_child";
+		char *argv_for_program[] = { filename, NULL };
+
+		execv(filename, argv_for_program);;
+	} else {
+		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;
+		}
+	}
+
+	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
+}
+
 static void test_prctl_unmerge(void)
 {
 	const unsigned int size = 2 * MiB;
@@ -536,7 +583,7 @@  static void test_prot_none(void)
 
 int main(int argc, char **argv)
 {
-	unsigned int tests = 7;
+	unsigned int tests = 8;
 	int err;
 
 #ifdef __NR_userfaultfd
@@ -576,6 +623,7 @@  int main(int argc, char **argv)
 
 	test_prctl();
 	test_prctl_fork();
+	test_prctl_fork_exec();
 	test_prctl_unmerge();
 
 	err = ksft_get_fail_cnt();