From: Andrei Vagin <avagin@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Dmitry Safonov <dima@arista.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 0/6] arm64: add the time namespace support
Date: Mon, 13 Jul 2020 18:57:43 -0700 [thread overview]
Message-ID: <20200714015743.GA843937@gmail.com> (raw)
In-Reply-To: <20200705064055.GA28894@gmail.com>
On Sat, Jul 04, 2020 at 11:40:55PM -0700, Andrei Vagin wrote:
> On Wed, Jun 24, 2020 at 01:33:15AM -0700, Andrei Vagin wrote:
> > Allocate the time namespace page among VVAR pages and add the logic
> > to handle faults on VVAR properly.
> >
> > If a task belongs to a time namespace then the VVAR page which contains
> > the system wide VDSO data is replaced with a namespace specific page
> > which has the same layout as the VVAR page. That page has vdso_data->seq
> > set to 1 to enforce the slow path and vdso_data->clock_mode set to
> > VCLOCK_TIMENS to enforce the time namespace handling path.
> >
> > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
> > update of the VDSO data is in progress, is not really affecting regular
> > tasks which are not part of a time namespace as the task is spin waiting
> > for the update to finish and vdso_data->seq to become even again.
> >
> > If a time namespace task hits that code path, it invokes the corresponding
> > time getter function which retrieves the real VVAR page, reads host time
> > and then adds the offset for the requested clock which is stored in the
> > special VVAR page.
> >
>
> > v2: Code cleanups suggested by Vincenzo.
> > v3: add a comment in __arch_get_timens_vdso_data.
> > v4: - fix an issue reported by the lkp robot.
> > - vvar has the same size with/without CONFIG_TIME_NAMESPACE, but the
> > timens page isn't allocated on !CONFIG_TIME_NAMESPACE. This
> > simplifies criu/vdso migration between different kernel configs.
> > v5: - Code cleanups suggested by Mark Rutland.
> > - In vdso_join_timens, mmap_write_lock is downgraded to
> > mmap_read_lock. The VMA list isn't changed there, zap_page_range
> > doesn't require mmap_write_lock.
> >
> > Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> > Reviewed-by: Dmitry Safonov <dima@arista.com>
>
> Hello Will and Catalin,
>
> Have you had a chance to look at this patch set? I think it is ready to be
> merged. Let me know if you have any questions.
*friendly ping*
If I am doing something wrong, let me know.
>
> Thanks,
> Andrei
>
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next prev parent reply other threads:[~2020-07-14 1:59 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 8:33 [PATCH v5 0/6] arm64: add the time namespace support Andrei Vagin
2020-06-24 8:33 ` [PATCH 1/6] arm64/vdso: use the fault callback to map vvar pages Andrei Vagin
[not found] ` <159561069973.19270.10637845392621633755.b4-ty@arm.com>
2020-07-27 6:45 ` Andrei Vagin
2020-06-24 8:33 ` [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-06-24 15:18 ` Christian Brauner
2020-06-25 8:25 ` Andrei Vagin
2020-06-24 8:33 ` [PATCH 3/6] arm64/vdso: Add time namespace page Andrei Vagin
2020-06-24 8:33 ` [PATCH 4/6] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-06-24 8:33 ` [PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA Andrei Vagin
2020-06-24 8:33 ` [PATCH 6/6] arm64: enable time namespace support Andrei Vagin
2020-07-05 6:40 ` [PATCH v5 0/6] arm64: add the " Andrei Vagin
2020-07-14 1:57 ` Andrei Vagin [this message]
2020-07-22 18:15 ` Catalin Marinas
2020-07-23 17:41 ` Andrei Vagin
2020-07-23 20:25 ` Thomas Gleixner
2020-07-24 11:01 ` Catalin Marinas
2020-07-24 13:22 ` Thomas Gleixner
2020-07-24 13:30 ` Christian Brauner
2020-07-24 14:40 ` Catalin Marinas
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