From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: <serge@hallyn.com>, <ebiederm@xmission.com>,
<agruenba@redhat.com>, <linux-api@vger.kernel.org>,
<oleg@redhat.com>, <linux-kernel@vger.kernel.org>,
<paul@paul-moore.com>, <ktkhai@virtuozzo.com>,
<viro@zeniv.linux.org.uk>, <avagin@openvz.org>,
<linux-fsdevel@vger.kernel.org>, <mtk.manpages@gmail.com>,
<akpm@linux-foundation.org>, <luto@amacapital.net>,
<gorcunov@openvz.org>, <mingo@kernel.org>,
<keescook@chromium.org>
Subject: [PATCH 0/2] nsfs: Introduce ioctl to set vector of ns_last_pid's on pid ns hierarhy
Date: Mon, 17 Apr 2017 20:34:37 +0300 [thread overview]
Message-ID: <149245014695.17600.12640895883798122726.stgit@localhost.localdomain> (raw)
On implementing of nested pid namespaces support in CRIU
(checkpoint-restore in userspace tool) we run into
the situation, that it's impossible to create a task with
specific NSpid effectively. After commit 49f4d8b93ccf
"pidns: Capture the user namespace and filter ns_last_pid"
it is impossible to set ns_last_pid on any pid namespace,
except task's active pid_ns (before the commit it was possible
to set it for pid_ns_for_children). Thus, if a restored task
in a container has more than one pid_ns levels, the restorer
code must have a task helper for every pid namespace
of the task's pid_ns hierarhy.
This is a big problem, because of communication with
a helper for every pid_ns in the hierarchy is not cheap
and not performance-good. It implies many wakeups of helpers
to create a single task (independently, how you communicate
with the helpers). So, this patchset tries to decide the problem.
It introduces a namespaces-specific ioctls and implements the
realization for pid_ns, which allows to write a vector of last
pids on pid_ns hierarchy.
The vector is passed as a ":"-delimited string with pids,
written in reverse order. The first number corresponds to
the opened namespace ns_last_pid, the second is to its parent, etc.
If you have the pid namespaces hierarchy like:
pid_ns1 (grand father)
|
v
pid_ns2 (father)
|
v
pid_ns3 (child)
and the ns of task's of pid_ns3 is open, then the corresponding
vector will be "last_ns_pid3:last_ns_pid2:last_ns_pid1". This
vector may be short and it may contain less levels, for example,
"last_ns_pid3:last_ns_pid2" or even "last_ns_pid3", in dependence
of which levels you want to populate. Numbers last_ns_pidX are
just numbers written in decimal form.
---
Kirill Tkhai (2):
nsfs: Add namespace-specific ioctl (NS_SPECIFIC_IOC)
pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy
fs/nsfs.c | 4 ++
include/linux/proc_ns.h | 1 +
include/uapi/linux/nsfs.h | 11 ++++++
kernel/pid_namespace.c | 88 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 104 insertions(+)
--
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
next reply other threads:[~2017-04-17 17:35 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 17:34 Kirill Tkhai [this message]
2017-04-17 17:36 ` [PATCH 1/2] nsfs: Add namespace-specific ioctl (NS_SPECIFIC_IOC) Kirill Tkhai
2017-04-17 17:36 ` [PATCH 2/2] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
2017-04-19 20:27 ` Serge E. Hallyn
2017-04-24 19:03 ` Cyrill Gorcunov
2017-04-26 15:53 ` Oleg Nesterov
2017-04-26 16:11 ` Kirill Tkhai
2017-04-26 16:33 ` Kirill Tkhai
2017-04-26 16:32 ` Eric W. Biederman
2017-04-26 16:43 ` Kirill Tkhai
2017-04-26 17:01 ` Eric W. Biederman
2017-04-27 16:12 ` Oleg Nesterov
2017-04-27 16:17 ` Kirill Tkhai
2017-04-27 16:22 ` Oleg Nesterov
2017-04-28 9:17 ` Kirill Tkhai
2017-05-02 16:33 ` Oleg Nesterov
2017-05-02 17:22 ` Eric W. Biederman
2017-05-02 17:33 ` Kirill Tkhai
2017-05-02 21:13 ` Eric W. Biederman
2017-05-03 10:20 ` Kirill Tkhai
2017-04-27 16:39 ` Eric W. Biederman
2017-04-28 9:22 ` Kirill Tkhai
2017-04-27 16:16 ` Oleg Nesterov
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