On Thu, 1 Dec 2016, John Stultz wrote: > Yes, you're right here and apologies, as I wasn't being precise. In > this case time does go backward, but its limited to within the current > interval (just as it would be with a narrow clocksource wrapping > fully). But without this patch, when the overflow occurs, if the > signed bit is set, the signed shift pulls the sign bits down, the time > can go backwards far beyond the current interval, which causes major > wreckage. Backwards is backwards, no matter how much. Depending on the computation which sees the timejump you can end up with major crap as well. Think NTP, PTP, PPS or whatever is able to tweak timekeeping in really bad ways. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html