Em Wed, Nov 13, 2013 at 12:22:49AM +0100, Ingo Molnar escreveu: > Hm, this is unexpected I think: > > hubble:~> perf top --stdio -u mingo > Error: > You may not have permission to collect stats. > Consider tweaking /proc/sys/kernel/perf_event_paranoid: > -1 - Not paranoid at all > 0 - Disallow raw tracepoint access for unpriv > 1 - Disallow cpu events for unpriv > 2 - Disallow kernel profiling for unpriv > > hubble:~> cat /proc/sys/kernel/perf_event_paranoid > -1 > > (perf is the latest version from tip:perf/core)
https://lkml.org/lkml/2012/1/26/142 Fell thru the cracks, summary: > > > +++ b/kernel/events/core.c > > > @@ -2636,7 +2636,8 @@ find_lively_task_by_vpid(pid_t vpid) > > > /* Reuse ptrace permission checks for now. */ > > > err = -EACCES; > > > - if (!ptrace_may_access(task, PTRACE_MODE_READ)) > > > + if (perf_paranoid_tracepoint_raw() && > > > + !ptrace_may_access(task, PTRACE_MODE_READ)) > > > goto errout; > > > return task; > > > ptrace_may_access(task, PTRACE_MODE_READ) fails for some tasks > > > owned by the user because, IIRC, in __ptrace_may_access: > > Which tasks are these, are they privileged in any sense? > IIRC one of them was a child of sshd, that runs as root and then changes > the child ownership to the user logging in. - Arnaldo -- 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/
