linux-kernel - Re: [PATCH v4 2/2] pidfd: add tests for NSpid info in fdinfo

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Date:   Wed, 13 Nov 2019 13:20:03 +0100
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Naresh Kamboju <naresh.kamboju@...aro.org>
Cc:     Christian Kellner <ckellner@...hat.com>,
        open list <linux-kernel@...r.kernel.org>,
        linux-api@...r.kernel.org, Jann Horn <jannh@...gle.com>,
        Christian Kellner <christian@...lner.me>,
        Christian Brauner <christian@...ntu.com>,
        Shuah Khan <shuah@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Michal Hocko <mhocko@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Elena Reshetova <elena.reshetova@...el.com>,
        Roman Gushchin <guro@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Aleksa Sarai <cyphar@...har.com>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, joel@...lfernandes.org
Subject: Re: [PATCH v4 2/2] pidfd: add tests for NSpid info in fdinfo

On Wed, Nov 13, 2019 at 05:22:33PM +0530, Naresh Kamboju wrote:
> Hi Christian,

Hi Naresh,


[+Cc Joel since this is _not related_ to the fdinfo patches but rather
 the polling tests]

Thanks for following up here. See for more comments below.

> 
> On Tue, 15 Oct 2019 at 15:37, Christian Brauner
> <christian.brauner@...ntu.com> wrote:
> >
> > On Mon, Oct 14, 2019 at 06:20:33PM +0200, Christian Kellner wrote:
> > > From: Christian Kellner <christian@...lner.me>
> > >
> > > Add a test that checks that if pid namespaces are configured the fdinfo
> > > file of a pidfd contains an NSpid: entry containing the process id in
> > > the current and additionally all nested namespaces. In the case that
> > > a pidfd is from a pid namespace not in the same namespace hierarchy as
> > > the process accessing the fdinfo file, ensure the 'NSpid' shows 0 for
> > > that pidfd, analogous to the 'Pid' entry.
> > >
> > > Signed-off-by: Christian Kellner <christian@...lner.me>
> >
> > That looks reasonable to me.
> 
> on arm64 Juno-r2, Hikey (hi6220) and dragonboard 410c and arm32
> Beagleboard x15 test pidfd_test failed.
> and on x86_64 and i386 test fails intermittently with TIMEOUT error.
> Test code is being used from linux next tree.
> 
> Juno-r2 test output:
> --------------------------
> # selftests pidfd pidfd_test
> pidfd: pidfd_test_ #
> # TAP version 13
> version: 13_ #
> # 1..4
> : _ #
> # # Parent pid 10586
> Parent: pid_10586 #
> # # Parent Waiting for Child (10587) to complete.
> Parent: Waiting_for #
> # # Time waited for child 0
> Time: waited_for #
> # Bail out! pidfd_poll check for premature notification on child
> thread exec test Failed
> out!: pidfd_poll_check #
> # # Planned tests != run tests (4 != 0)
> Planned: tests_!= #
> # # Pass 0 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0
> Pass: 0_Fail #
> [FAIL] 1 selftests pidfd pidfd_test # exit=1
> selftests: pidfd_pidfd_test [FAIL]
> 
> arm32 x15 output log,
> -----------------------------
> # selftests pidfd pidfd_test
> pidfd: pidfd_test_ #
> [FAIL] 1 selftests pidfd pidfd_test # TIMEOUT
> selftests: pidfd_pidfd_test [FAIL]
> 
> x86_64 output log,
> -------------------------
> # selftests pidfd pidfd_test
> pidfd: pidfd_test_ #
> [FAIL] 1 selftests pidfd pidfd_test # TIMEOUT
> selftests: pidfd_pidfd_test [FAIL]
> 
> Test results comparison,
> https://qa-reports.linaro.org/lkft/linux-mainline-oe/tests/kselftest/pidfd_pidfd_test
> https://qa-reports.linaro.org/lkft/linux-next-oe/tests/kselftest/pidfd_pidfd_test
> 
> link,
> https://lkft.validation.linaro.org/scheduler/job/993549#L17835

Note, that this failure is _not_ related to the fdinfo and NSpid patches
here.
It's rather related to the polling testing code that Joel added. Iirc,
then it is timing sensitive.
I'll try to make some room this week to look into this.

	Christian