Re: [PATCH v5 0/6] arm64: add the time namespace support

[Thomas Gleixner <tglx@linutronix.de>]

Catalin Marinas <catalin.marinas@arm.com> writes:
> On Thu, Jul 23, 2020 at 10:25:35PM +0200, Thomas Gleixner wrote:
>> Andrei Vagin <avagin@gmail.com> writes:
>> > On Wed, Jul 22, 2020 at 07:15:06PM +0100, Catalin Marinas wrote:
>> >
>> > I don't think that we need to handle this case in the kernel. Users
>> > must understand what they are doing and have to write code so that avoid
>> > these sort of situations. In general, I would say that in most cases it
>> > is a bad idea to call setns from a signal handler.
>> 
>> This should not be supported in the first place and just let the
>> offender die right there.
>
> It would have been nice if we caught the offender easily but since
> signal handling doesn't have to be paired with sigreturn(), the kernel
> can't tell whether setns() is called in the wrong context. I guess we
> just have to live with this (maybe document the restriction in
> time_namespaces(7) or setns(2)).

Yes, I know that it's more or less impossible. The 'should' was just
wishful thinking :)

But yes, proper documentation is required.

Thanks,

        tglx