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 <[email protected]>
> ---
>
> 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
>
