On Thu, Oct 08, 2020 at 07:39:40AM +0200, Michael Weiß wrote: > Time namespaces make it possible to virtualize time inside of > containers, e.g., it is feasible to reset the uptime of a container > to zero by setting the time namespace offset for boottime to the > negated current value of the CLOCK_BOOTTIME. > > However, the boot time stamp provided by getboottime64() does not > take care of time namespaces. The resulting boot time stamp 'btime' > provided by /proc/stat does not show a plausible time stamp inside > the time namespace of a container. > > We address this by shifting the value returned by getboottime64() > by subtracting the boottime offset of the time namespace. > (A selftest to check the expected /proc/stat 'btime' inside the > namespace is provided.) > > Further, to avoid to show processes as time travelers inside of the > time namespace the boottime offset then needs to be added to the > start_bootime provided by the task_struct. > > v2 Changes: > Fixed compile errors with TIME_NS not set in config > Reported-by: kernel test robot <l...@intel.com>
Hey Michael, Thanks for the patches. This looks like a good idea to me. Since /proc/uptime is now virtualized according to the timens the caller is in btime has to be virtualized too. Christian
