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Thu, 21 Sep 2023 12:26:56 -0400 (EDT) References: <20230920190117.784151-1-shr@devkernel.io> <20230920190117.784151-3-shr@devkernel.io> User-agent: mu4e 1.10.1; emacs 28.2.50 From: Stefan Roesch To: David Hildenbrand Cc: kernel-team@fb.com, akpm@linux-foundation.org, hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 2/2] mm/ksm: Test case for prctl fork/exec workflow Date: Thu, 21 Sep 2023 09:25:46 -0700 In-reply-to: Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 5FA0920020 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 8hcifinpt3um8yy8eai41mkj91zqnt18 X-HE-Tag: 1695313617-106498 X-HE-Meta: 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 ff3Hy9Yh RuwjOGaiiuohcxihBOeYFQCUMmiQkKBZtV653VeuXZ0jq1BN7mBUHbwaq3lJcBF8jEa11nGYSItW+wXCCpRaxW/7QBEIM9VLZ0ZS8DLTXns3red0ghSt+IFdusQAiBKSxeU3nnuQra8qwE2hqb7sSlQDq1pSY2WqgNOKHIyoy42+bisX3F5Wb4QRPXA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: David Hildenbrand 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 >> --- >> .../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