Commit 0374af1d authored by Stefan Roesch's avatar Stefan Roesch Committed by Andrew Morton
Browse files

mm/ksm: test case for prctl fork/exec workflow 

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.

Link: https://lkml.kernel.org/r/20230922211141.320789-3-shr@devkernel.io


Signed-off-by: default avatarStefan Roesch <shr@devkernel.io>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Carl Klemm <carl@uvos.xyz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3c6f33b7

tools/testing/selftests/mm/ksm_functional_tests.c

+65 −1
Original line number Diff line number Diff line
@@ -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 +480,64 @@ 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. */

	return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 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 +595,13 @@ 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 +639,7 @@ int main(int argc, char **argv) 


	test_prctl();

	test_prctl_fork();

	test_prctl_fork_exec();

	test_prctl_unmerge();



	err = ksft_get_fail_cnt();