On Thu, Feb 5, 2015 at 9:22 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Thu, 5 Feb 2015 21:07:27 +0100 > Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > >> > Is this Paul's version of the patch or mine? If it is just mine, do you >> > know if Paul's version triggers this too? >> > >> >> This one which entered Pauls rcu-next tree. >> >> [1] http://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=rcu/next&id=2b27cf7317d8a99a50bead9faccd54b46b6f0c41 > > That's mine. > > It looks like the condition will be tested before it calls and rcu > code. Which is why I was confused that it still gave a splat. Paul > posted a patch before this that did the check outside the trace point. > > This one: > > http://marc.info/?l=linux-kernel&m=142310961217650&w=2 > >> >> >> ( I did not build from scratch but re-invoking make "updated" the >> >> files touched by Steven's patch, see attached build-log. ) >> >> >> >> Unfortunately, the call-trace remains when doing an offlining of cpu1. >> >> ( It's good to see it's reproducible. ) >> > >> > Was the tracepoint enabled? Or was there some other rcu call that >> > triggered this. Or would cpu_online(smp_processor_id()) return true at >> > this point? >> > >> >> Thanks Steve for jumping into this one! >> >> Good point. >> I looked at my kernel-config (which I already sent :-)). >> >> Do I need to enable...? >> >> # CONFIG_RCU_TRACE is not set >> >> ...or even more? >> > > What I meant by the tracepoint being enabled, was not that it was > configured in (I'm assuming it was), but that you started tracing? > > echo 1 > /sys/kernel/debug/tracing/events/enable > > or > > echo 1 > /sys/kernel/debug/tracing/events/tlb/tlb_flushed/enable > NO, I did not start any tracing before doing my testing. # cat /sys/kernel/debug/tracing/events/enable 0 # echo 1 > /sys/kernel/debug/tracing/events/enable # cat /sys/kernel/debug/tracing/events/enable X # LC_ALL=C cat /sys/kernel/debug/tracing/events/tlb/tlb_flushed/enable cat: /sys/kernel/debug/tracing/events/tlb/tlb_flushed/enable: No such file or directory Looks like I need to enable...? # CONFIG_DEBUG_TLBFLUSH is not set To answer your question... # cat /sys/devices/system/cpu/cpu1/online 1 # echo 0 > /sys/devices/system/cpu/cpu1/online # cat /sys/devices/system/cpu/cpu1/online 0 [ 375.337050] intel_pstate CPU 1 exiting [ 375.351069] smpboot: CPU 1 is now offline So, this did not happen this time. - Sedat - -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
