On 08/29/17 12:10, Luboš Doležel wrote: > Hello, > > I'm hitting a strange bug on some of my Linux systems with various 4.x > kernels. > > I cannot set the system time to anything before the current system time. > > This includes ntpd not being able to keep the clock in sync if the system > clock is a little too fast. So it's not limited to just setting the time back > to the 90s, but it actually breaks time synchronization on my server system. > > Essentially, settimeofday() and clock_settime() system calls succeed, but any > subsequent gettimeofday() etc. call will return unaltered time. > > E.g.: > > $ sudo date -s 1998-08-01 > Sat Aug 1 00:00:00 CEST 1998 > $ date > Tue Aug 29 20:59:25 CEST 2017
Is ntp daemon running? > I have been able to reproduce the problem on these CPUs: > > * Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz > * Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz > > I *cannot* reproduce the problem on these CPUs, even if I boot the same > kernel version as on the CPUs above: > > * Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz > * Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz > * Various even older CPUs > > I tried to google the problem, but turned up with nothing. This brings > several questions: > > 1) What the hell? > 2) Am I the only one having this problem? > 3) Can the Linux kernel developers possibly do something about this, if this > problem is confirmed? -- ~Randy
