From: Oleg Nesterov <oleg@redhat.com>
To: Adrian Reber <areber@redhat.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>,
Eric Biederman <ebiederm@xmission.com>,
Pavel Emelianov <xemul@virtuozzo.com>,
Jann Horn <jannh@google.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
linux-kernel@vger.kernel.org, Andrei Vagin <avagin@gmail.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Radostin Stoyanov <rstoyanov1@gmail.com>
Subject: Re: [PATCH v6 1/2] fork: extend clone3() to support setting a PID
Date: Tue, 13 Aug 2019 16:30:24 +0200 [thread overview]
Message-ID: <20190813143023.GC6971@redhat.com> (raw)
In-Reply-To: <20190812200939.23784-1-areber@redhat.com>
On 08/12, Adrian Reber wrote:
>
> The main motivation to add set_tid to clone3() is CRIU.
>
> To restore a process with the same PID/TID CRIU currently uses
> /proc/sys/kernel/ns_last_pid. It writes the desired (PID - 1) to
> ns_last_pid and then (quickly) does a clone(). This works most of the
> time, but it is racy. It is also slow as it requires multiple syscalls.
>
> Extending clone3() to support set_tid makes it possible restore a
> process using CRIU without accessing /proc/sys/kernel/ns_last_pid and
> race free (as long as the desired PID/TID is available).
>
> This clone3() extension places the same restrictions (CAP_SYS_ADMIN)
> on clone3() with set_tid as they are currently in place for ns_last_pid.
>
> Signed-off-by: Adrian Reber <areber@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
next prev parent reply other threads:[~2019-08-13 14:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 20:09 [PATCH v6 1/2] fork: extend clone3() to support setting a PID Adrian Reber
2019-08-12 20:09 ` [PATCH v6 2/2] selftests: add tests for clone3() Adrian Reber
2019-08-13 14:46 ` Christian Brauner
2019-08-13 16:14 ` Christian Brauner
2019-08-12 20:43 ` [PATCH v6 1/2] fork: extend clone3() to support setting a PID Andrei Vagin
2019-08-12 21:02 ` Adrian Reber
2019-08-12 21:50 ` Christian Brauner
2019-08-12 21:53 ` Andrei Vagin
2019-08-13 9:45 ` Christian Brauner
2019-08-13 14:30 ` Oleg Nesterov [this message]
2019-08-14 10:04 ` Christian Brauner
2019-08-14 9:50 ` Pavel Emelianov
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