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Date:   Fri, 29 Oct 2021 10:32:48 +0200
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Li Zhijian <lizhijian@cn.fujitsu.com>
Cc:     linux-kselftest@vger.kernel.org, shuah@kernel.org,
        linux-kernel@vger.kernel.org,
        Christian Brauner <christian@brauner.io>,
        Philip Li <philip.li@intel.com>,
        kernel test robot <lkp@intel.com>
Subject: Re: [PATCH 2/2] ksefltest: pidfd: Fix wait_states: Test terminated
 by timeout
Message-ID: <20211029083248.7vttuxbwbtdylrnq@wittgenstein>
References: <20211029024528.8086-1-lizhijian@cn.fujitsu.com>
 <20211029024528.8086-2-lizhijian@cn.fujitsu.com>
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On Fri, Oct 29, 2021 at 10:45:28AM +0800, Li Zhijian wrote:
> 0Day/LKP observed that the kselftest blocks foever 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);
> 
> we can reproduce it by:
> $ while true; do make run_tests -C pidfd; done
> 
> a delay to ensure that the parent can see child process WCONTINUED.
> 
> CC: Christian Brauner <christian@brauner.io>
> CC: Shuah Khan <shuah@kernel.org>
> CC: Philip Li <philip.li@intel.com>
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> ---

Not a fan of the usleep() solution but if it fixes it it's fine for
a test, I think.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>