From: Christian Brauner <christian.brauner@ubuntu.com>
To: Andrei Vagin <avagin@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Dmitry Safonov <dima@arista.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace
Date: Fri, 19 Jun 2020 17:38:12 +0200 [thread overview]
Message-ID: <20200619153812.2d6anaynb4p37qv2@wittgenstein> (raw)
In-Reply-To: <20200616075545.312684-3-avagin@gmail.com>
On Tue, Jun 16, 2020 at 12:55:41AM -0700, Andrei Vagin wrote:
> The VVAR page layout depends on whether a task belongs to the root or
> non-root time namespace. Whenever a task changes its namespace, the VVAR
> page tables are cleared and then they will be re-faulted with a
> corresponding layout.
>
> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Dmitry Safonov <dima@arista.com>
> Signed-off-by: Andrei Vagin <avagin@gmail.com>
> ---
> arch/arm64/kernel/vdso.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index b0aec4e8c9b4..df4bb736d28a 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -125,6 +125,38 @@ static int __vdso_init(enum vdso_abi abi)
> return 0;
> }
>
> +#ifdef CONFIG_TIME_NS
> +/*
> + * The vvar page layout depends on whether a task belongs to the root or
> + * non-root time namespace. Whenever a task changes its namespace, the VVAR
> + * page tables are cleared and then they will re-faulted with a
> + * corresponding layout.
> + * See also the comment near timens_setup_vdso_data() for details.
> + */
> +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> +{
> + struct mm_struct *mm = task->mm;
> + struct vm_area_struct *vma;
> +
> + if (mmap_write_lock_killable(mm))
> + return -EINTR;
Hey,
Just a heads-up I'm about to plumb CLONE_NEWTIME support into setns()
which would mean that vdso_join_timens() ould not be allowed to fail
anymore to make it easy to switch to multiple namespaces atomically. So
this would probably need to be changed to mmap_write_lock() which I've
already brought up upstream:
https://lore.kernel.org/lkml/20200611110221.pgd3r5qkjrjmfqa2@wittgenstein/
(Assuming that people agree. I just sent the series and most people here
are Cced.)
Thanks!
Christian
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next prev parent reply other threads:[~2020-06-19 15:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 7:55 [PATCH v4 0/6] arm64: add the time namespace support Andrei Vagin
2020-06-16 7:55 ` [PATCH 1/6] arm64/vdso: use the fault callback to map vvar pages Andrei Vagin
2020-06-16 10:59 ` Mark Rutland
2020-06-18 7:27 ` Andrei Vagin
2020-06-16 7:55 ` [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-06-16 11:24 ` Mark Rutland
2020-06-16 13:47 ` Dmitry Safonov
2020-06-19 15:38 ` Christian Brauner [this message]
2020-06-16 7:55 ` [PATCH 3/6] arm64/vdso: Add time namespace page Andrei Vagin
2020-06-16 7:55 ` [PATCH 4/6] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-06-16 7:55 ` [PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA Andrei Vagin
2020-06-16 7:55 ` [PATCH 6/6] arm64: enable time namespace support Andrei Vagin
-- strict thread matches above, loose matches on Subject: below --
2020-06-24 8:33 [PATCH v5 0/6] arm64: add the " 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
2020-06-02 18:02 [PATCH RESEND v3 0/6] arm64: add the time namespace support Andrei Vagin
2020-06-02 18:02 ` [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-04-16 5:26 [PATCH v3 0/6] arm64: add the time namespace support Andrei Vagin
2020-04-16 5:26 ` [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
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