Ingo Molnar <[EMAIL PROTECTED]> writes: > * Eric W. Biederman <[EMAIL PROTECTED]> wrote: > >> /proc/timer_stats currently reports the user of a timer by pid, which >> is a reasonable approach. However if you are not in the initial pid >> namespace the pid that is reported is nonsense. >> >> Therefore until we can make timer_stats pid namespace safe just >> disable it in the build if pid namespace support is selected so we at >> least know we have a conflict. > > What the heck??? Please solve this properly instead of hiding it. > /proc/timer_stats is damn useful and it's a must-have for powertop to > work.
Hmm. Perhaps the dependency conflict should go in the other direction then. My goal is to document the issue while a proper fix is being written. I have known about this for all of about 1 day now. It was added since last time I went through the kernel and made a thorough sweep of pid users. What the proper fix is isn't even obvious at this point. Possibly it is making /proc/timer_stats disappear in child pid namespaces. Which we don't currently have the infrastructure fore. Possibly it is reworking the stats collection so we store a struct pid * instead of a pid_t value. So we would know if the reader of the value can even see processes you have collected stats for. It is going to take a bit to digest what is going on and solve this properly. In the same vein do we actively have interesting user space programs using /proc/sched_debug? It is the same class of problem. Yet another interface talking to user space with pids. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
