From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89EC5C38A02 for ; Sun, 30 Oct 2022 08:10:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229717AbiJ3IKB (ORCPT ); Sun, 30 Oct 2022 04:10:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229636AbiJ3IKA (ORCPT ); Sun, 30 Oct 2022 04:10:00 -0400 Received: from mail3.bemta32.messagelabs.com (mail3.bemta32.messagelabs.com [195.245.230.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D05A6477; Sun, 30 Oct 2022 01:09:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fujitsu.com; s=170520fj; t=1667117395; i=@fujitsu.com; bh=pYw7uqjyEvZaLsNuFiKYxapJZFv8SQRZj+Lqn+bU7gY=; h=Message-ID:Date:MIME-Version:Subject:From:To:CC:References: In-Reply-To:Content-Type:Content-Transfer-Encoding; b=pouJlnki67wus/8JOla19P0yEUMLGyf3I5TxLiALmtjUI+/jziRHq5u+TKZ/DwqnF oX2ot1/0J/uVb8kXJ77hrkAgj9UUYjy0mBhNgf2x1Wy/dAdYiehpPSwe1ESa286i+C lGx2F03nuSWyualeMmc50XLXzeTLDQstaxotECsFvApsnZw9J1woXULuZkXMYr5JTV 8R278om0YNc6OJosbyPYuinvFLW0fJ3eNg2M92Rg6iikgAcAOKtt2r4qYnsWbbprRD gtTwqlBgv/Z927difv8cHH1e7y1zH385NVi7Uw0gfuY9UHvMRe11epnoGsDU8T2cHu DN30EBxXpi6Cg== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPKsWRWlGSWpSXmKPExsViZ8OxWTfIMC7 ZYNcPFovXhz8xWlzeNYfNYvqd92wWlw5dZLKY8nIduwOrx+I9L5k8Nq3qZPP4vEkugDmKNTMv Kb8igTVjw75JjAUXpSra951ibGDsE+9i5OIQEtjIKDFx6h4WCGcJk8TD/5+hnG2MEivObmPtY uTk4BWwk9i77zg7iM0ioCqx8VsfE0RcUOLkzCcsILaoQITEw0eTgGwODmGBcIkpS9RBwswC4h K3nswHK2cT0JC413KTEcQWEQiQOHzrOCNEjbPEyzcb2UBsIYFSiVdz5oPZnAL2Eo1TJrNB1Fh ILH5zkB3Clpdo3jqbGcSWEFCUONL5lwXCrpCYNauNCcJWk7h6bhPzBEbhWUgunYXkpFlIxs5C MnYBI8sqRrPi1KKy1CJdQ1O9pKLM9IyS3MTMHL3EKt1EvdRS3fLU4hJdQ73E8mK91OJiveLK3 OScFL281JJNjMC4SilmL97B+GDZH71DjJIcTEqivPm/Y5OF+JLyUyozEosz4otKc1KLDzHKcH AoSfB268UlCwkWpaanVqRl5gBjHCYtwcGjJMJbqQKU5i0uSMwtzkyHSJ1i1OU4uGv/XmYhlrz 8vFQpcd4CA6AiAZCijNI8uBGwdHOJUVZKmJeRgYFBiKcgtSg3swRV/hWjOAejkjDvPpBLeDLz SuA2vQI6ggnoiPRJUSBHlCQipKQamLRv/klQ7+nWuXzg3YXyqzcbXtWeVgrsvFV258CK3T5Hr DK+R+/Oyb+y6tG3h0rhXRU1PYzNx2taLooHmN/5fTlAZMFdt80TnnSVigt4S31oVYqMnLl/0r K0yTG398pv45nqZNO18MXE3bfqJYJanB92ezzzZ9p07dL1PVo16UnqpZa+9Q7zYjRsPkTu4LT v3nFGNiWiZ3HupFm3brQK/WHriDnC/bjB6NNLrm15pyVUvwW/8WbM3GGabSz5gnO1d/Uq99Np 5xR0TDMfmyTIXnf6WSPFterlOs658qVXMrjMV9oGqes8KZhWJ6XJo/LbVD1y345lHNLfW1sT0 xedmVV+KGT6nrCcZYu7C3avVWIpzkg01GIuKk4EAKbQypyyAwAA X-Env-Sender: lizhijian@fujitsu.com X-Msg-Ref: server-6.tower-585.messagelabs.com!1667117393!224574!1 X-Originating-IP: [62.60.8.179] X-SYMC-ESS-Client-Auth: outbound-route-from=pass X-StarScan-Received: X-StarScan-Version: 9.100.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 2117 invoked from network); 30 Oct 2022 08:09:54 -0000 Received: from unknown (HELO n03ukasimr04.n03.fujitsu.local) (62.60.8.179) by server-6.tower-585.messagelabs.com with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 30 Oct 2022 08:09:54 -0000 Received: from n03ukasimr04.n03.fujitsu.local (localhost [127.0.0.1]) by n03ukasimr04.n03.fujitsu.local (Postfix) with ESMTP id AB69B151; Sun, 30 Oct 2022 08:09:53 +0000 (GMT) Received: from R01UKEXCASM126.r01.fujitsu.local (R01UKEXCASM126 [10.183.43.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by n03ukasimr04.n03.fujitsu.local (Postfix) with ESMTPS id 9E9AD142; Sun, 30 Oct 2022 08:09:53 +0000 (GMT) Received: from [10.167.226.45] (10.167.226.45) by R01UKEXCASM126.r01.fujitsu.local (10.183.43.178) with Microsoft SMTP Server (TLS) id 15.0.1497.32; Sun, 30 Oct 2022 08:09:50 +0000 Message-ID: Date: Sun, 30 Oct 2022 16:09:40 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v3] ksefltests: pidfd: Fix wait_states: Test terminated by timeout Content-Language: en-US From: Li Zhijian To: , , CC: , Philip Li References: <1662001807-7-1-git-send-email-lizhijian@fujitsu.com> <8b921394-e7c4-2c85-da76-0ebd05e6ef07@fujitsu.com> In-Reply-To: <8b921394-e7c4-2c85-da76-0ebd05e6ef07@fujitsu.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.167.226.45] X-ClientProxiedBy: G08CNEXCHPEKD07.g08.fujitsu.local (10.167.33.80) To R01UKEXCASM126.r01.fujitsu.local (10.183.43.178) X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org ping again On 29/09/2022 08:56, Li Zhijian wrote: > ping > > > On 01/09/2022 11:10, Li Zhijian wrote: >> 0Day/LKP observed that the kselftest blocks forever since one of the >> pidfd_wait doesn't terminate in 1 of 30 runs. After digging into >> the source, we found that it blocks at: >> ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0); >> >> wait_states has below testing flow: >>    CHILD                 PARENT >>    ---------------+-------------- >> 1 STOP itself >> 2                   WAIT for CHILD STOPPED >> 3                   SIGNAL CHILD to CONT >> 4 CONT >> 5 STOP itself >> 5'                  WAIT for CHILD CONT >> 6                   WAIT for CHILD STOPPED >> >> The problem is that the kernel cannot ensure the order of 5 and 5', once >> 5 goes first, the test will fail. >> >> we can reproduce it by: >> $ while true; do make run_tests -C pidfd; done >> >> Introduce a blocking read in child process to make sure the parent can >> check its WCONTINUED. >> >> CC: Philip Li >> Reported-by: kernel test robot >> Signed-off-by: Li Zhijian >> Reviewed-by: Christian Brauner (Microsoft) >> --- >> I have almost forgotten this patch since the former version post over 6 months >> ago. This time I just do a rebase and update the comments. >> V3: fixes description and add review tag >> V2: rewrite with pipe to avoid usleep >> --- >>   tools/testing/selftests/pidfd/pidfd_wait.c | 10 ++++++++++ >>   1 file changed, 10 insertions(+) >> >> diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c >> index 070c1c876df1..c3e2a3041f55 100644 >> --- a/tools/testing/selftests/pidfd/pidfd_wait.c >> +++ b/tools/testing/selftests/pidfd/pidfd_wait.c >> @@ -95,20 +95,28 @@ static int sys_waitid(int which, pid_t pid, siginfo_t *info, int options, >>           .flags = CLONE_PIDFD | CLONE_PARENT_SETTID, >>           .exit_signal = SIGCHLD, >>       }; >> +    int pfd[2]; >>       pid_t pid; >>       siginfo_t info = { >>           .si_signo = 0, >>       }; >>   +    ASSERT_EQ(pipe(pfd), 0); >>       pid = sys_clone3(&args); >>       ASSERT_GE(pid, 0); >>         if (pid == 0) { >> +        char buf[2]; >> + >> +        close(pfd[1]); >>           kill(getpid(), SIGSTOP); >> +        ASSERT_EQ(read(pfd[0], buf, 1), 1); >> +        close(pfd[0]); >>           kill(getpid(), SIGSTOP); >>           exit(EXIT_SUCCESS); >>       } >>   +    close(pfd[0]); >>       ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL), 0); >>       ASSERT_EQ(info.si_signo, SIGCHLD); >>       ASSERT_EQ(info.si_code, CLD_STOPPED); >> @@ -117,6 +125,8 @@ static int sys_waitid(int which, pid_t pid, siginfo_t *info, int options, >>       ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0), 0); >>         ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0); >> +    ASSERT_EQ(write(pfd[1], "C", 1), 1); >> +    close(pfd[1]); >>       ASSERT_EQ(info.si_signo, SIGCHLD); >>       ASSERT_EQ(info.si_code, CLD_CONTINUED); >>       ASSERT_EQ(info.si_pid, parent_tid); >