On Fri, Feb 06, 2015 at 03:06:55PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx> > > When taking a CPU down for suspend and resume, a tracepoint may be called > when the CPU has been designated offline. As tracepoints require RCU for > protection, they must not be called if the current CPU is offline. > > Unfortunately, trace_tlb_flush() is called in this scenario as was noted > by LOCKDEP: > > ... > > Disabling non-boot CPUs ... > intel_pstate CPU 1 exiting > > =============================== > smpboot: CPU 1 didn't die... > [ INFO: suspicious RCU usage. ] > 3.19.0-rc7-next-20150204.1-iniza-small #1 Not tainted > ------------------------------- > include/trace/events/tlb.h:35 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > RCU used illegally from offline CPU! > rcu_scheduler_active = 1, debug_locks = 0 > no locks held by swapper/1/0. > > stack backtrace: > CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.19.0-rc7-next-20150204.1-iniza-small #1 > Hardware name: SAMSUNG ELECTRONICS CO., LTD. 530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013 > 0000000000000001 ffff88011a44fe18 ffffffff817e370d 0000000000000011 > ffff88011a448290 ffff88011a44fe48 ffffffff810d6847 ffff8800c66b9600 > 0000000000000001 ffff88011a44c000 ffffffff81cb3900 ffff88011a44fe78 > Call Trace: > [<ffffffff817e370d>] dump_stack+0x4c/0x65 > [<ffffffff810d6847>] lockdep_rcu_suspicious+0xe7/0x120 > [<ffffffff810b71a5>] idle_task_exit+0x205/0x2c0 > [<ffffffff81054c4e>] play_dead_common+0xe/0x50 > [<ffffffff81054ca5>] native_play_dead+0x15/0x140 > [<ffffffff8102963f>] arch_cpu_idle_dead+0xf/0x20 > [<ffffffff810cd89e>] cpu_startup_entry+0x37e/0x580 > [<ffffffff81053e20>] start_secondary+0x140/0x150 > intel_pstate CPU 2 exiting > > ... > > By converting the tlb_flush tracepoint to a TRACE_EVENT_CONDITION where the > condition is cpu_online(smp_processor_id()), we can avoid calling RCU protected > code when the CPU is offline. > > Link: http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=JB8B9a0EQv-eGzQ@xxxxxxxxxxxxxx > > Reported-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> > Suggested-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > --- > include/trace/events/tlb.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h > index 13391d288107..0e7635765153 100644 > --- a/include/trace/events/tlb.h > +++ b/include/trace/events/tlb.h > @@ -13,11 +13,13 @@ > { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, \ > { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" } > > -TRACE_EVENT(tlb_flush, > +TRACE_EVENT_CONDITION(tlb_flush, > > TP_PROTO(int reason, unsigned long pages), > TP_ARGS(reason, pages), > > + TP_CONDITION(cpu_online(smp_processor_id())), > + > TP_STRUCT__entry( > __field( int, reason) > __field(unsigned long, pages) > -- > 2.1.4 > > -- 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
