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Date: Fri, 29 Oct 2021 08:41:47 +0000
From: "lizhijian@...itsu.com" <lizhijian@...itsu.com>
To: Christian Brauner <christian.brauner@...ntu.com>,
"lizhijian@...itsu.com" <lizhijian@...itsu.com>
CC: "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
"shuah@...nel.org" <shuah@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...capital.net>,
Will Drewry <wad@...omium.org>,
Christian Brauner <christian@...uner.io>,
Philip Li <philip.li@...el.com>,
"xuyang2018.jy@...itsu.com" <xuyang2018.jy@...itsu.com>
Subject: Re: [PATCH 1/2] kselftest: signal all child processes
On 29/10/2021 16:31, Christian Brauner wrote:
> On Fri, Oct 29, 2021 at 10:45:27AM +0800, Li Zhijian wrote:
>> We have some many cases that will create child process as well, such as
>> pidfd_wait. Previously, we will signal/kill the parent process when it
>> is time out, but this signal will not be sent to its child process. In
>> such case, if child process doesn't terminate itself, ksefltest framework
>> will hang forever.
>>
>> below ps tree show the situation when ksefltest is blocking:
>> root 1172 0.0 0.0 5996 2500 ? S 07:03 0:00 \_ /bin/bash /lkp/lkp/src/tests/kernel-selftests
>> root 1216 0.0 0.0 4392 1976 ? S 07:03 0:00 \_ make run_tests -C pidfd
>> root 1218 0.0 0.0 2396 1652 ? S 07:03 0:00 \_ /bin/sh -c BASE_DIR="/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests"; . /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/runner.sh; if [ "X" != "X" ]; then per_test_logging=1; fi; run_many /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_fdinfo_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_open_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_poll_test /usr/src/perf_selftests-x86_64-rhel-8.
>> root 12491 0.0 0.0 2396 132 ? S 07:03 0:00 \_ /bin/sh -c BASE_DIR="/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests"; . /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/runner.sh; if [ "X" != "X" ]; then per_test_logging=1; fi; run_many /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_fdinfo_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_open_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_poll_test /usr/src/perf_selftests-x86_64-rhe
>> root 12492 0.0 0.0 2396 132 ? S 07:03 0:00 \_ /bin/sh -c BASE_DIR="/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests"; . /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/runner.sh; if [ "X" != "X" ]; then per_test_logging=1; fi; run_many /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_fdinfo_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_open_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_poll_test /usr/src/perf_selftests-x86_64
>> root 12493 0.0 0.0 2396 132 ? S 07:03 0:00 \_ /bin/sh -c BASE_DIR="/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests"; . /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/runner.sh; if [ "X" != "X" ]; then per_test_logging=1; fi; run_many /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_fdinfo_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_open_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_poll_test /usr/src/perf_selftests-x8
>> root 12496 0.0 0.0 2396 132 ? S 07:03 0:00 \_ /bin/sh -c BASE_DIR="/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests"; . /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/runner.sh; if [ "X" != "X" ]; then per_test_logging=1; fi; run_many /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_fdinfo_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_open_test /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/pidfd/pidfd_poll_test /usr/src/perf_selftest
>> root 12498 0.0 0.0 10564 6116 ? S 07:03 0:00 \_ perl /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-519d81956ee277b4419c723adfb154603c2565ba/tools/testing/selftests/kselftest/prefix.pl
>> root 12503 0.0 0.0 2452 112 ? T 07:03 0:00 ./pidfd_wait
>> root 12621 0.0 0.0 2372 1600 ? SLs 07:04 0:00 /usr/sbin/watchdog
>> root 19438 0.0 0.0 992 60 ? Ss 07:39 0:00 /lkp/lkp/src/bin/event/wakeup activate-monitor
>>
>> Here we group all its child processes so that kill() can signal all of
>> them in timeout.
>>
>> CC: Kees Cook <keescook@...omium.org>
>> CC: Andy Lutomirski <luto@...capital.net>
>> CC: Will Drewry <wad@...omium.org>
>> CC: Shuah Khan <shuah@...nel.org>
>> CC: Christian Brauner <christian@...uner.io>
>> CC: Philip Li <philip.li@...el.com>
>> Suggested-by: yang xu <xuyang2018.jy@...fujitsu.com>
>> Signed-off-by: Li Zhijian <lizhijian@...fujitsu.com>
>> ---
> Seems sensible. Is it guaranteed that t->pid is neither 0 nor 1?
that's true, we fire the timer(reach here) only if fork() succeeds.
Thanks
Zhijian
> If not
> then maybe sanity check t->pid at least for not being 1 as negating that
> would mean "signal everything that you have permission to signal". :)
>
> Otherwise,
> Acked-by: Christian Brauner <christian.brauner@...ntu.com>
>
>> tools/testing/selftests/kselftest_harness.h | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
>> index ae0f0f33b2a6..c7251396e7ee 100644
>> --- a/tools/testing/selftests/kselftest_harness.h
>> +++ b/tools/testing/selftests/kselftest_harness.h
>> @@ -875,7 +875,8 @@ static void __timeout_handler(int sig, siginfo_t *info, void *ucontext)
>> }
>>
>> t->timed_out = true;
>> - kill(t->pid, SIGKILL);
>> + // signal process group
>> + kill(-(t->pid), SIGKILL);
>> }
>>
>> void __wait_for_test(struct __test_metadata *t)
>> @@ -985,6 +986,7 @@ void __run_test(struct __fixture_metadata *f,
>> ksft_print_msg("ERROR SPAWNING TEST CHILD\n");
>> t->passed = 0;
>> } else if (t->pid == 0) {
>> + setpgrp();
>> t->fn(t, variant);
>> if (t->skip)
>> _exit(255);
>> --
>> 2.33.0
>>
>>
>>
>
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