From: ebiederm@xmission.com (Eric W. Biederman)
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Christian Brauner <christian.brauner@ubuntu.com>,
"Michael Kerrisk \(man-pages\)" <mtk.manpages@gmail.com>,
Dmitry Safonov <dima@arista.com>,
Andrei Vagin <avagin@openvz.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Adrian Reber <adrian@lisas.de>, Andy Lutomirski <luto@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Cyrill Gorcunov <gorcunov@openvz.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Jann Horn <jannh@google.com>, Jeff Dike <jdike@addtoit.com>,
Oleg Nesterov <oleg@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Shuah Khan <shuah@kernel.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
containers <containers@lists.linux-foundation.org>,
criu@openvz.org, Linux API <linux-api@vger.kernel.org>,
x86@kernel.org, Andrei Vagin <avagin@gmail.com>
Subject: Re: Time Namespaces: CLONE_NEWTIME and clone3()?
Date: Mon, 17 Feb 2020 20:37:55 -0600 [thread overview]
Message-ID: <87lfp0boxo.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <874kvossh4.fsf@nanos.tec.linutronix.de> (Thomas Gleixner's message of "Tue, 18 Feb 2020 00:29:27 +0100")
Thomas Gleixner <tglx@linutronix.de> writes:
> Christian Brauner <christian.brauner@ubuntu.com> writes:
>> On Mon, Feb 17, 2020 at 10:47:53PM +0100, Michael Kerrisk (man-pages) wrote:
>>> Actually, I think the alternative you propose just here is better. I
>>> imagine there are times when one will want to create multiple
>>> namespaces with a single call to clone3(), including a time namespace.
>>> I think this should be allowed by the API. And, otherwise, clone3()
>>> becomes something of a second-class citizen for creating namespaces.
>>> (I don't really get the "less invasive" argument. Implementing this is
>>> just a piece of kernel to code to make user-space's life a bit simpler
>>> and more consistent.)
>>
>> I don't particularly mind either way. If there's actual users that need
>> to set it at clone3() time then we can extend it. So I'd like to hear
>> what Adrian, Dmitry, and Thomas think since they are well-versed how
>> this will be used in the wild. I'm weary of exposing a whole new uapi
>> struct and extending clone3() without any real use-case but I'm happy to
>> if there is!
>
> I really have no clue. I merily helped getting this in shape without
> creating havoc for timekeeping and VDSO. I have to punt to the container
> wizards.
Short version. If you are going to do migration of a container with
CRIU you want the time namespace in your container. Possibly you can
avoid creating the time namespace until restore, but I don't think so.
Without the time namespace you get all kinds of applications that use
monotonic timers that will see their timers be ill behaved (probably
going backwards) over a checkpoint-restart event.
Eric
next prev parent reply other threads:[~2020-02-18 2:40 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 1:26 [PATCHv8 00/34] kernel: Introduce Time Namespace Dmitry Safonov
2019-11-12 1:26 ` [PATCHv8 01/34] lib/vdso: Add unlikely() hint into vdso_read_begin() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 02/34] lib/vdso: make do_hres and do_coarse as __always_inline Dmitry Safonov
2020-01-10 9:45 ` Vincenzo Frascino
2020-01-10 11:42 ` Thomas Gleixner
2020-01-10 11:47 ` Vincenzo Frascino
2020-01-10 12:02 ` Thomas Gleixner
2020-01-10 12:18 ` Vincenzo Frascino
2020-01-13 5:27 ` Andrei Vagin
2020-01-13 19:09 ` [tip: timers/core] lib/vdso: Mark do_hres() and do_coarse() " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 03/34] ns: Introduce Time Namespace Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2020-01-27 14:12 ` [PATCHv8 03/34] " Dmitry Vyukov
2020-01-27 14:19 ` Dmitry Safonov
2020-02-17 14:20 ` Time Namespaces: CLONE_NEWTIME and clone3()? Michael Kerrisk
2020-02-17 14:59 ` Christian Brauner
2020-02-17 21:47 ` Michael Kerrisk (man-pages)
2020-02-17 23:03 ` Christian Brauner
2020-02-17 23:29 ` Thomas Gleixner
2020-02-18 2:37 ` Eric W. Biederman [this message]
2020-02-18 17:11 ` Adrian Reber
2020-02-18 17:26 ` Christian Brauner
2019-11-12 1:26 ` [PATCHv8 04/34] time: Add timens_offsets to be used for tasks in timens Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] time: Add timens_offsets to be used for tasks in time namespace tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 05/34] posix-clocks: Rename the clock_get() callback to clock_get_timespec() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 06/34] posix-clocks: Rename .clock_get_timespec() callbacks accordingly Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 07/34] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 08/34] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 09/34] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:26 ` [PATCHv8 10/34] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 11/34] posix-clocks: Wire up clock_gettime() with timens offsets Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 12/34] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] time: " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 13/34] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 14/34] posix-timers: Make timer_settime() " Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 15/34] alarmtimer: Make nanosleep " Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] alarmtimer: Make nanosleep() " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 16/34] hrtimers: Prepare hrtimer_nanosleep() for time namespaces Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 17/34] posix-timers: Make clock_nanosleep() time namespace aware Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 18/34] fs/proc: Respect boottime inside time namespace for /proc/uptime Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 19/34] x86/vdso: Restrict splitting VVAR VMA Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 20/34] lib/vdso: Prepare for time namespace support Dmitry Safonov
2020-01-12 10:32 ` Thomas Gleixner
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2020-01-14 13:02 ` tip-bot2 for Thomas Gleixner
2019-11-12 1:27 ` [PATCHv8 21/34] x86/vdso: Provide vdso_data offset on vvar_page Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 22/34] x86/vdso: Add timens page Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] x86/vdso: Add time napespace page tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 23/34] time: Allocate per-timens vvar page Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 24/34] x86/vdso: Handle faults on timens page Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 25/34] x86/vdso: On timens page fault prefault also VVAR page Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 26/34] x86/vdso: Zap vvar pages on switch a time namspace Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] x86/vdso: Zap vvar pages when switching to a time namespace tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 27/34] fs/proc: Introduce /proc/pid/timens_offsets Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 28/34] selftests/timens: Add Time Namespace test for supported clocks Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 29/34] selftests/timens: Add a test for timerfd Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 30/34] selftests/timens: Add a test for clock_nanosleep() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 31/34] selftests/timens: Add procfs selftest Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Dmitry Safonov
2020-01-14 13:02 ` tip-bot2 for Dmitry Safonov
2019-11-12 1:27 ` [PATCHv8 32/34] selftests/timens: Add timer offsets test Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 33/34] selftests/timens: Add a simple perf test for clock_gettime() Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-12 1:27 ` [PATCHv8 34/34] selftests/timens: Check for right timens offsets after fork and exec Dmitry Safonov
2020-01-13 19:09 ` [tip: timers/core] " tip-bot2 for Andrei Vagin
2020-01-14 13:02 ` tip-bot2 for Andrei Vagin
2019-11-21 18:05 ` [PATCHv8 00/34] kernel: Introduce Time Namespace Andrei Vagin
2019-12-11 20:38 ` Dmitry Safonov
2020-01-09 21:09 ` Thomas Gleixner
2020-01-10 9:52 ` Vincenzo Frascino
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