Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow

[Thomas Gleixner <tglx@linutronix.de>]

On Fri, 9 Oct 2015, Miroslav Lichvar wrote:
> On Fri, Oct 09, 2015 at 10:46:16AM +0100, Thomas Gleixner wrote:
> > On Thu, 8 Oct 2015, Miroslav Lichvar wrote:
> > > Applications are not allowed to rely on system time being sane?
> > > To me the current behavior looks like the kernel is throwing the
> > > applications off a cliff, while it's the only thing that can fly :).
> > 
> > As Arnd said, you are creating a wrong sense of safety. They fall off
> > the cliff with your changes as well. The fall is just different. Think
> > about timeouts, user space overflows of time_t etc.
> 
> I think vast majority of them won't fall. It doesn't prevent all
> problems, but at least the userspace agrees with kernel on what the
> current time it is, that looks to me like the most difficult one to
> fix in applications.
> 
> > We need to fix all of it, no matter what.
> 
> Yeah, that would be nice, but I don't think it's realistic.
> 
> Do you feel the same about preventing the time from reaching
> KTIME_MAX?

That's going to happen in ~500 years from now.

Thanks,

	tglx