Re: [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace

[Dmitry Safonov]

Hi Mark,

On 6/16/20 12:24 PM, Mark Rutland wrote:
> On Tue, Jun 16, 2020 at 12:55:41AM -0700, Andrei Vagin wrote:
[..]
>> Whenever a task changes its namespace, the VVAR
>> page tables are cleared and then they will be re-faulted with a
>> corresponding layout.
> 
> How does this work for multi-threaded applications? Are there any
> concerns w.r.t. atomicity of the change?

Multi-threaded applications can't setns() for time namespace,
timens_install():

:       if (!current_is_single_threaded())
:               return -EUSERS;

Thanks,
          Dmitry