Messages in this thread | | | Date | Sun, 14 Feb 2016 22:05:22 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v2 2/2] tracing/rcu: don't trace rcu_callback on offline CPUs |
| |
On Sun, Feb 14, 2016 at 09:50:18AM +0300, Denis Kirjanov wrote: > Tracepoints use RCU for protection and they must not be called on > offline CPUS. So make this tracepoint conditional.
Good catch! Queued for review and testing.
Thanx, Paul
> NFO: suspicious RCU usage. ] > [ 413.344670] 4.4.0-00006-g0fe53e8-dirty #33 Tainted: G S > [ 413.344672] ------------------------------- > [ 413.344673] include/trace/events/rcu.h:457 suspicious rcu_dereference_check() usage! > [ 413.344674] > other info that might help us debug this: > > [ 413.344676] > RCU used illegally from offline CPU! > rcu_scheduler_active = 1, debug_locks = 1 > [ 413.344678] no locks held by swapper/4/0. > [ 413.344679] > stack backtrace: > [ 413.344682] CPU: 4 PID: 0 Comm: swapper/4 Tainted: G S 4.4.0-00006-g0fe53e8-dirty #33 > [ 413.344683] Call Trace: > [ 413.344692] [c0000005b76b7800] [c0000000008bb080] .dump_stack+0x98/0xd4 (unreliable) > [ 413.344698] [c0000005b76b7880] [c00000000010c8b8] .lockdep_rcu_suspicious+0x108/0x170 > [ 413.344703] [c0000005b76b7910] [c00000000013b9e4] .__call_rcu.constprop.60+0x264/0x600 > [ 413.344708] [c0000005b76b79e0] [c0000000002bceec] .put_object+0x5c/0x80 > [ 413.344712] [c0000005b76b7a60] [c00000000029a368] .kmem_cache_free+0x298/0x450 > [ 413.344716] [c0000005b76b7b00] [c000000000093494] .__mmdrop+0x54/0x150 > [ 413.344720] [c0000005b76b7b90] [c0000000000e4010] .idle_task_exit+0x130/0x140 > [ 413.344725] [c0000005b76b7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310 > [ 413.344730] [c0000005b76b7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60 > [ 413.344734] [c0000005b76b7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40 > [ 413.344738] [c0000005b76b7db0] [c000000000101e8c] .cpu_startup_entry+0x50c/0x560 > [ 413.344741] [c0000005b76b7ed0] [c000000000043bd8] .start_secondary+0x328/0x360 > [ 413.344746] [c0000005b76b7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14 > > Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org> > --- > > v2: Fix the build error that was made > while sending the pacthes from another machine > > include/trace/events/rcu.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h > index ef72c4a..793d306b 100644 > --- a/include/trace/events/rcu.h > +++ b/include/trace/events/rcu.h > @@ -428,13 +428,15 @@ TRACE_EVENT(rcu_prep_idle, > * number of lazy callbacks queued, and the fourth element is the > * total number of callbacks queued. > */ > -TRACE_EVENT(rcu_callback, > +TRACE_EVENT_CONDITION(rcu_callback, > > TP_PROTO(const char *rcuname, struct rcu_head *rhp, long qlen_lazy, > long qlen), > > TP_ARGS(rcuname, rhp, qlen_lazy, qlen), > > + TP_CONDITION(cpu_online(raw_smp_processor_id())), > + > TP_STRUCT__entry( > __field(const char *, rcuname) > __field(void *, rhp) > -- > 2.4.0 >
| |