linux-kernel - Re: [PATCH v11 2/2] selftests: add tests for clone3() with *set

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Date:   Fri, 15 Nov 2019 14:20:18 -0800
From:   Andrei Vagin <avagin@...il.com>
To:     Adrian Reber <areber@...hat.com>
Cc:     Christian Brauner <christian.brauner@...ntu.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Pavel Emelyanov <ovzxemul@...il.com>,
        Jann Horn <jannh@...gle.com>, Oleg Nesterov <oleg@...hat.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...ux.ibm.com>,
        Radostin Stoyanov <rstoyanov1@...il.com>
Subject: Re: [PATCH v11 2/2] selftests: add tests for clone3() with *set_tid

On Fri, Nov 15, 2019 at 01:36:21PM +0100, Adrian Reber wrote:
> This tests clone3() with *set_tid to see if all desired PIDs are working
> as expected. The tests are trying multiple invalid input parameters as
> well as creating processes while specifying a certain PID in multiple
> PID namespaces at the same time.
> 
> Additionally this moves common clone3() test code into clone3_selftests.h.
> 
> Signed-off-by: Adrian Reber <areber@...hat.com>
> ---
> v9:
>  - applied all changes from Christian's review (except using the
>    NSpid: parsing code from selftests/pidfd/pidfd_fdinfo_test.c)
> 
> v10:
>  - added even more '\n' and include file fixes (Christian)
> 
> v11:
>  - added more return code checking at multiple places (Andrei)
>  - also add set_tid/set_tid_size to internal struct (Andrei)

I think we can add a test case to trigger the issue what I found in the
previous version of the kernel patch. You can find my version of this
test case in the attached patch.

nit: we need to flush stdout and stderr buffers before calling the raw
clone3 syscall and _exit(). Otherwise, some log messages can be lost and
some of them can be printed twice.

To trigger this issue, you can run the test and redirect its output to
file or pipe:

$ ./clone3_set_tid | cat

I have attached the patch to address both these problems. It is a draft
version and may require some work.

Adrian and Christian, it is up to you to decide whether we want to
update the current patch or to fix this on top by a separate patch.

Thanks,
Andrei

View attachment "patch" of type "text/plain" (2587 bytes)