Re: lots of suspicious RCU traces

[Sergey Senozhatsky <sergey.senozhatsky@gmail.com>]

On (10/16/12 23:49), Dave Jones wrote:
> I just triggered this while fuzz testing. All traces happened
> in quick succession.
> 

I can easily reproduce this one

[ 5714.696329] ===============================
[ 5714.696332] [ INFO: suspicious RCU usage. ]
[ 5714.696336] 3.7.0-rc2-dbg-01220-g698b6f8-dirty #1376 Not tainted
[ 5714.696338] -------------------------------
[ 5714.696341] include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
[ 5714.696343] 
other info that might help us debug this:

[ 5714.696347] 
RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 1
[ 5714.696350] RCU used illegally from extended quiescent state!
[ 5714.696354] 2 locks held by coretemp-sensor/16214:
[ 5714.696356]  #0:  (&(&sighand->siglock)->rlock){-.-...}, at: [<ffffffff8105a543>] ptrace_notify+0x53/0x90
[ 5714.696373]  #1:  (rcu_read_lock){.+.+..}, at: [<ffffffff81066c55>] __task_pid_nr_ns+0x5/0x1b0
[ 5714.696385] 
stack backtrace:
[ 5714.696389] Pid: 16214, comm: coretemp-sensor Not tainted 3.7.0-rc2-dbg-01220-g698b6f8-dirty #1376
[ 5714.696392] Call Trace:
[ 5714.696403]  [<ffffffff810a8142>] lockdep_rcu_suspicious+0xe2/0x130
[ 5714.696408]  [<ffffffff81066dc5>] __task_pid_nr_ns+0x175/0x1b0
[ 5714.696413]  [<ffffffff81066c55>] ? __task_pid_nr_ns+0x5/0x1b0
[ 5714.696418]  [<ffffffff8105867f>] ptrace_do_notify+0x5f/0xb0
[ 5714.696423]  [<ffffffff8105a554>] ptrace_notify+0x64/0x90
[ 5714.696431]  [<ffffffff8100fa7d>] syscall_trace_leave+0x8d/0x220
[ 5714.696439]  [<ffffffff815dc7c1>] ? int_very_careful+0x5/0xd
[ 5714.696444]  [<ffffffff810ac7c5>] ? trace_hardirqs_on_caller+0x105/0x190
[ 5714.696450]  [<ffffffff815dc7fd>] int_check_syscall_exit_work+0x34/0x3d



small question,

ptrace_notify() and forward calls are able to both indirectly and directly call schedule(),
/* direct call from ptrace_stop()*/,
should, in this case, rcu_user_enter() be called before tracehook_report_syscall_exit(regs, step)
and ptrace chain?


	-ss


> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 2 locks on stack by trinity-main/9791:
>  #0: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff8801435dce20, at: [<ffffffff8108afd3>] ptrace_notify+0x53/0x90
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81097e75>] __task_pid_nr_ns+0x5/0x1a0
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81097fd5>] __task_pid_nr_ns+0x165/0x1a0
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff8108924f>] ptrace_do_notify+0x5f/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 2 locks on stack by trinity-main/9791:
>  #0: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff8801435dce20, at: [<ffffffff8108afd3>] ptrace_notify+0x53/0x90
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81097e75>] __task_pid_nr_ns+0x5/0x1a0
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81097fa1>] __task_pid_nr_ns+0x131/0x1a0
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff8108924f>] ptrace_do_notify+0x5f/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810ba5dc>] active_load_balance_cpu_stop+0x3ac/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff816c1030>] ? _raw_spin_unlock_irq+0x30/0x80
>  [<ffffffff810b0de1>] ? get_parent_ip+0x11/0x50
>  [<ffffffff810b0de1>] ? get_parent_ip+0x11/0x50
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/sched/fair.c:4538 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810ba665>] active_load_balance_cpu_stop+0x435/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff816c1030>] ? _raw_spin_unlock_irq+0x30/0x80
>  [<ffffffff810b0de1>] ? get_parent_ip+0x11/0x50
>  [<ffffffff810b0de1>] ? get_parent_ip+0x11/0x50
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 4 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
>  #3: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810b6a53>] cpuacct_charge+0x13/0x230
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810b6c0c>] cpuacct_charge+0x1cc/0x230
>  [<ffffffff810b6a53>] ? cpuacct_charge+0x13/0x230
>  [<ffffffff810bafa4>] update_curr+0x104/0x270
>  [<ffffffff810bc244>] enqueue_entity+0x44/0x720
>  [<ffffffff810bc962>] enqueue_task_fair+0x42/0xf0
>  [<ffffffff810af326>] enqueue_task+0x66/0x80
>  [<ffffffff810b01c3>] activate_task+0x23/0x30
>  [<ffffffff810b8aec>] move_task+0x3c/0x50
>  [<ffffffff810ba4b2>] active_load_balance_cpu_stop+0x282/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 4 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
>  #3: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810b6a53>] cpuacct_charge+0x13/0x230
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810b6bd5>] cpuacct_charge+0x195/0x230
>  [<ffffffff810b6a53>] ? cpuacct_charge+0x13/0x230
>  [<ffffffff810bafa4>] update_curr+0x104/0x270
>  [<ffffffff810bc244>] enqueue_entity+0x44/0x720
>  [<ffffffff810bc962>] enqueue_task_fair+0x42/0xf0
>  [<ffffffff810af326>] enqueue_task+0x66/0x80
>  [<ffffffff810b01c3>] activate_task+0x23/0x30
>  [<ffffffff810b8aec>] move_task+0x3c/0x50
>  [<ffffffff810ba4b2>] active_load_balance_cpu_stop+0x282/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 4 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
>  #3: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810b6a53>] cpuacct_charge+0x13/0x230
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810b6b70>] cpuacct_charge+0x130/0x230
>  [<ffffffff810b6a53>] ? cpuacct_charge+0x13/0x230
>  [<ffffffff810bafa4>] update_curr+0x104/0x270
>  [<ffffffff810bc244>] enqueue_entity+0x44/0x720
>  [<ffffffff810bc962>] enqueue_task_fair+0x42/0xf0
>  [<ffffffff810af326>] enqueue_task+0x66/0x80
>  [<ffffffff810b01c3>] activate_task+0x23/0x30
>  [<ffffffff810b8aec>] move_task+0x3c/0x50
>  [<ffffffff810ba4b2>] active_load_balance_cpu_stop+0x282/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by migration/2/24:
>  #0: held:     (&rq->lock){-.-.-.}, instance: ffff8801481d4a98, at: [<ffffffff810ba558>] active_load_balance_cpu_stop+0x328/0x490
>  #1: held:     (&rq->lock/1){..-.-.}, instance: ffff8801483d4a98, at: [<ffffffff810ba569>] active_load_balance_cpu_stop+0x339/0x490
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ba324>] active_load_balance_cpu_stop+0xf4/0x490
> 
> stack backtrace:
> Pid: 24, comm: migration/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810ba615>] active_load_balance_cpu_stop+0x3e5/0x490
>  [<ffffffff810ba324>] ? active_load_balance_cpu_stop+0xf4/0x490
>  [<ffffffff81107923>] ? cpu_stopper_thread+0xb3/0x1d0
>  [<ffffffff810ba230>] ? select_task_rq_fair+0xad0/0xad0
>  [<ffffffff8110794b>] cpu_stopper_thread+0xdb/0x1d0
>  [<ffffffff816c5a59>] ? sub_preempt_count+0x79/0xd0
>  [<ffffffff816bef69>] ? __schedule+0x499/0xa40
>  [<ffffffff81107870>] ? cpu_stop_queue_work+0x80/0x80
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/rcutree.c:360 Illegal idle entry in RCU read-side critical section.!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 1 lock on stack by rcuc/2/22:
>  #0: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff816c5855>] __atomic_notifier_call_chain+0x5/0x140
> 
> stack backtrace:
> Pid: 22, comm: rcuc/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  <IRQ>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff8112a2d3>] rcu_eqs_enter_common.isra.41+0x1b3/0x1f0
>  [<ffffffff8112d1dd>] rcu_irq_exit+0xbd/0x100
>  [<ffffffff8107ba2b>] irq_exit+0x8b/0xe0
>  [<ffffffff816cbc0b>] smp_apic_timer_interrupt+0x6b/0x98
>  [<ffffffff816cab32>] apic_timer_interrupt+0x72/0x80
>  <EOI>  [<ffffffff810e4472>] ? mark_held_locks+0xb2/0x130
>  [<ffffffff810736d5>] ? vprintk_emit+0x1b5/0x600
>  [<ffffffff816b3b1b>] printk+0x61/0x63
>  [<ffffffff810dfa6f>] lockdep_rcu_suspicious+0x2f/0x130
>  [<ffffffff816c597c>] __atomic_notifier_call_chain+0x12c/0x140
>  [<ffffffff816c5855>] ? __atomic_notifier_call_chain+0x5/0x140
>  [<ffffffff816c59a6>] atomic_notifier_call_chain+0x16/0x20
>  [<ffffffff810d34da>] profile_handoff_task+0x1a/0x30
>  [<ffffffff8106dc18>] __put_task_struct+0x88/0x140
>  [<ffffffff81075c28>] delayed_put_task_struct+0x48/0x170
>  [<ffffffff8112acda>] rcu_do_batch.isra.22+0x15a/0x440
>  [<ffffffff8112c963>] rcu_cpu_kthread+0x143/0x670
>  [<ffffffff810a8464>] smpboot_thread_fn+0x1d4/0x300
>  [<ffffffff810a8290>] ? __smpboot_create_thread.part.2+0xc0/0xc0
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff816be985>] ? wait_for_common+0x135/0x180
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 1 lock on stack by rcuc/2/22:
>  #0: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff816c5855>] __atomic_notifier_call_chain+0x5/0x140
> 
> stack backtrace:
> Pid: 22, comm: rcuc/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff816c597c>] __atomic_notifier_call_chain+0x12c/0x140
>  [<ffffffff816c5855>] ? __atomic_notifier_call_chain+0x5/0x140
>  [<ffffffff816c59a6>] atomic_notifier_call_chain+0x16/0x20
>  [<ffffffff810d34da>] profile_handoff_task+0x1a/0x30
>  [<ffffffff8106dc18>] __put_task_struct+0x88/0x140
>  [<ffffffff81075c28>] delayed_put_task_struct+0x48/0x170
>  [<ffffffff8112acda>] rcu_do_batch.isra.22+0x15a/0x440
>  [<ffffffff8112c963>] rcu_cpu_kthread+0x143/0x670
>  [<ffffffff810a8464>] smpboot_thread_fn+0x1d4/0x300
>  [<ffffffff810a8290>] ? __smpboot_create_thread.part.2+0xc0/0xc0
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff816be985>] ? wait_for_common+0x135/0x180
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 1 lock on stack by rcuc/2/22:
>  #0: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff816c5855>] __atomic_notifier_call_chain+0x5/0x140
> 
> stack backtrace:
> Pid: 22, comm: rcuc/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff816c5948>] __atomic_notifier_call_chain+0xf8/0x140
>  [<ffffffff816c5855>] ? __atomic_notifier_call_chain+0x5/0x140
>  [<ffffffff816c59a6>] atomic_notifier_call_chain+0x16/0x20
>  [<ffffffff810d34da>] profile_handoff_task+0x1a/0x30
>  [<ffffffff8106dc18>] __put_task_struct+0x88/0x140
>  [<ffffffff81075c28>] delayed_put_task_struct+0x48/0x170
>  [<ffffffff8112acda>] rcu_do_batch.isra.22+0x15a/0x440
>  [<ffffffff8112c963>] rcu_cpu_kthread+0x143/0x670
>  [<ffffffff810a8464>] smpboot_thread_fn+0x1d4/0x300
>  [<ffffffff810a8290>] ? __smpboot_create_thread.part.2+0xc0/0xc0
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff816be985>] ? wait_for_common+0x135/0x180
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/sched/fair.c:4723 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 1 lock on stack by rcuc/2/22:
>  #0: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810bea25>] rebalance_domains+0x5/0x310
> 
> stack backtrace:
> Pid: 22, comm: rcuc/2 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  <IRQ>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810bed05>] rebalance_domains+0x2e5/0x310
>  [<ffffffff810bea25>] ? rebalance_domains+0x5/0x310
>  [<ffffffff810e4576>] ? trace_hardirqs_on_caller+0x86/0x1e0
>  [<ffffffff810bed7d>] run_rebalance_domains+0x4d/0x1c0
>  [<ffffffffa030d310>] ? dn_neigh_elist+0x40/0x160 [decnet]
>  [<ffffffff8107b520>] __do_softirq+0xf0/0x440
>  [<ffffffff816cb27c>] call_softirq+0x1c/0x30
>  <EOI>  [<ffffffff8101f175>] do_softirq+0xd5/0x110
>  [<ffffffff8112c968>] ? rcu_cpu_kthread+0x148/0x670
>  [<ffffffff8107b3eb>] local_bh_enable+0x11b/0x160
>  [<ffffffff8112c968>] rcu_cpu_kthread+0x148/0x670
>  [<ffffffff810a8464>] smpboot_thread_fn+0x1d4/0x300
>  [<ffffffff810a8290>] ? __smpboot_create_thread.part.2+0xc0/0xc0
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff816be985>] ? wait_for_common+0x135/0x180
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/sched/fair.c:2715 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 5 locks on stack by kworker/2:0/9822:
>  #0: blocked:  (events){.+.+.+}, instance: ffff880147814fd8, at: [<ffffffff810959c7>] process_one_work+0x197/0x780
>  #1: blocked:  ((&barr->work)){+.+...}, instance: ffff880083ad5d38, at: [<ffffffff810959c7>] process_one_work+0x197/0x780
>  #2: held:     (&x->wait#8){......}, instance: ffff88005a183e90, at: [<ffffffff810ab2b8>] complete+0x28/0x60
>  #3: held:     (&p->pi_lock){-.-.-.}, instance: ffff88003606cf78, at: [<ffffffff810b37f1>] try_to_wake_up+0x31/0x320
>  #4: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810b97c1>] select_task_rq_fair+0x61/0xad0
> 
> stack backtrace:
> Pid: 9822, comm: kworker/2:0 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810b9b10>] select_task_rq_fair+0x3b0/0xad0
>  [<ffffffff810b97c1>] ? select_task_rq_fair+0x61/0xad0
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff810b37f1>] ? try_to_wake_up+0x31/0x320
>  [<ffffffff810b387e>] try_to_wake_up+0xbe/0x320
>  [<ffffffff810b3af2>] default_wake_function+0x12/0x20
>  [<ffffffff810a8b75>] __wake_up_common+0x55/0x90
>  [<ffffffff810ab2b8>] ? complete+0x28/0x60
>  [<ffffffff810ab2d7>] complete+0x47/0x60
>  [<ffffffff81092422>] wq_barrier_func+0x12/0x20
>  [<ffffffff81095a37>] process_one_work+0x207/0x780
>  [<ffffffff810959c7>] ? process_one_work+0x197/0x780
>  [<ffffffff81092410>] ? destroy_work_on_stack+0x20/0x20
>  [<ffffffff81095fdc>] process_scheduled_works+0x2c/0x40
>  [<ffffffff8109652a>] worker_thread+0x2fa/0x440
>  [<ffffffff81096230>] ? rescuer_thread+0x240/0x240
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/sched/core.c:1216 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 5 locks on stack by kworker/2:0/9822:
>  #0: blocked:  (events){.+.+.+}, instance: ffff880147814fd8, at: [<ffffffff810959c7>] process_one_work+0x197/0x780
>  #1: blocked:  ((&barr->work)){+.+...}, instance: ffff880083ad5d38, at: [<ffffffff810959c7>] process_one_work+0x197/0x780
>  #2: held:     (&x->wait#8){......}, instance: ffff88005a183e90, at: [<ffffffff810ab2b8>] complete+0x28/0x60
>  #3: held:     (&p->pi_lock){-.-.-.}, instance: ffff88003606cf78, at: [<ffffffff810b37f1>] try_to_wake_up+0x31/0x320
>  #4: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810ae169>] ttwu_stat+0x49/0x280
> 
> stack backtrace:
> Pid: 9822, comm: kworker/2:0 Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810ae21c>] ttwu_stat+0xfc/0x280
>  [<ffffffff810ae169>] ? ttwu_stat+0x49/0x280
>  [<ffffffff810b3950>] try_to_wake_up+0x190/0x320
>  [<ffffffff810b3af2>] default_wake_function+0x12/0x20
>  [<ffffffff810a8b75>] __wake_up_common+0x55/0x90
>  [<ffffffff810ab2b8>] ? complete+0x28/0x60
>  [<ffffffff810ab2d7>] complete+0x47/0x60
>  [<ffffffff81092422>] wq_barrier_func+0x12/0x20
>  [<ffffffff81095a37>] process_one_work+0x207/0x780
>  [<ffffffff810959c7>] ? process_one_work+0x197/0x780
>  [<ffffffff81092410>] ? destroy_work_on_stack+0x20/0x20
>  [<ffffffff81095fdc>] process_scheduled_works+0x2c/0x40
>  [<ffffffff8109652a>] worker_thread+0x2fa/0x440
>  [<ffffffff81096230>] ? rescuer_thread+0x240/0x240
>  [<ffffffff8109d0cd>] kthread+0xed/0x100
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
>  [<ffffffff816c9dac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff8109cfe0>] ? kthread_create_on_node+0x160/0x160
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 2 locks on stack by trinity-main/9791:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81089031>] ptrace_stop+0xc1/0x280
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088a4e>] do_notify_parent_cldstop+0x2e/0x550
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81088de5>] do_notify_parent_cldstop+0x3c5/0x550
>  [<ffffffff81088a4e>] ? do_notify_parent_cldstop+0x2e/0x550
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8108906a>] ptrace_stop+0xfa/0x280
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff81089287>] ptrace_do_notify+0x97/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/signal.c:1756 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by trinity-main/9791:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81089031>] ptrace_stop+0xc1/0x280
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088a4e>] do_notify_parent_cldstop+0x2e/0x550
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088aa3>] do_notify_parent_cldstop+0x83/0x550
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81088ed8>] do_notify_parent_cldstop+0x4b8/0x550
>  [<ffffffff81088aa3>] ? do_notify_parent_cldstop+0x83/0x550
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8108906a>] ptrace_stop+0xfa/0x280
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff81089287>] ptrace_do_notify+0x97/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by trinity-main/9791:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81089031>] ptrace_stop+0xc1/0x280
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088a4e>] do_notify_parent_cldstop+0x2e/0x550
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088aa3>] do_notify_parent_cldstop+0x83/0x550
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81088d75>] do_notify_parent_cldstop+0x355/0x550
>  [<ffffffff81088aa3>] ? do_notify_parent_cldstop+0x83/0x550
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8108906a>] ptrace_stop+0xfa/0x280
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff81089287>] ptrace_do_notify+0x97/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/signal.c:1756 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by trinity-main/9791:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81089031>] ptrace_stop+0xc1/0x280
>  #1: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088a4e>] do_notify_parent_cldstop+0x2e/0x550
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff81088b37>] do_notify_parent_cldstop+0x117/0x550
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff81088f18>] do_notify_parent_cldstop+0x4f8/0x550
>  [<ffffffff81088b37>] ? do_notify_parent_cldstop+0x117/0x550
>  [<ffffffff810de02e>] ? put_lock_stats.isra.25+0xe/0x40
>  [<ffffffff8108906a>] ptrace_stop+0xfa/0x280
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff81089287>] ptrace_do_notify+0x97/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/sched/fair.c:2660 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 5 locks on stack by trinity-main/9791:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81089031>] ptrace_stop+0xc1/0x280
>  #1: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff880107520820, at: [<ffffffff81088e16>] do_notify_parent_cldstop+0x3f6/0x550
>  #2: held:     (&sig->wait_chldexit){......}, instance: ffff880035679528, at: [<ffffffff810ab327>] __wake_up_sync_key+0x37/0x80
>  #3: held:     (&p->pi_lock){-.-.-.}, instance: ffff880035738658, at: [<ffffffff810b37f1>] try_to_wake_up+0x31/0x320
>  #4: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff810b97c1>] select_task_rq_fair+0x61/0xad0
> 
> stack backtrace:
> Pid: 9791, comm: trinity-main Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810ba10c>] select_task_rq_fair+0x9ac/0xad0
>  [<ffffffff810b97c1>] ? select_task_rq_fair+0x61/0xad0
>  [<ffffffff810de049>] ? put_lock_stats.isra.25+0x29/0x40
>  [<ffffffff810b37f1>] ? try_to_wake_up+0x31/0x320
>  [<ffffffff810b387e>] try_to_wake_up+0xbe/0x320
>  [<ffffffff810b3af2>] default_wake_function+0x12/0x20
>  [<ffffffff8107586a>] child_wait_callback+0x5a/0x60
>  [<ffffffff810a8b75>] __wake_up_common+0x55/0x90
>  [<ffffffff810ab327>] ? __wake_up_sync_key+0x37/0x80
>  [<ffffffff810ab343>] __wake_up_sync_key+0x53/0x80
>  [<ffffffff81078b36>] __wake_up_parent+0x26/0x30
>  [<ffffffff81088e4e>] do_notify_parent_cldstop+0x42e/0x550
>  [<ffffffff81088b37>] ? do_notify_parent_cldstop+0x117/0x550
>  [<ffffffff8108906a>] ptrace_stop+0xfa/0x280
>  [<ffffffff81097e75>] ? __task_pid_nr_ns+0x5/0x1a0
>  [<ffffffff81089287>] ptrace_do_notify+0x97/0xb0
>  [<ffffffff8108afe4>] ptrace_notify+0x64/0x90
>  [<ffffffff8102be46>] tracehook_report_syscall_exit+0x36/0xb0
>  [<ffffffff810ab02c>] ? finish_task_switch+0x7c/0x120
>  [<ffffffff816ca143>] ? int_very_careful+0x5/0xd
>  [<ffffffff8102c269>] syscall_trace_leave+0x79/0x150
>  [<ffffffff816ca17f>] int_check_syscall_exit_work+0x34/0x3d
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by strace/1365:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81077402>] do_wait+0xb2/0x370
>  #1: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff8801435dce20, at: [<ffffffff8107652d>] wait_consider_task+0x11d/0xf40
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff8107655a>] wait_consider_task+0x14a/0xf40
> 
> stack backtrace:
> Pid: 1365, comm: strace Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff8107696c>] wait_consider_task+0x55c/0xf40
>  [<ffffffff8107655a>] ? wait_consider_task+0x14a/0xf40
>  [<ffffffff810774d3>] do_wait+0x183/0x370
>  [<ffffffff81078d75>] sys_wait4+0x75/0xf0
>  [<ffffffff81075810>] ? task_stopped_code+0x60/0x60
>  [<ffffffff816ca088>] tracesys+0xe1/0xe6
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> kernel/exit.c:1350 suspicious rcu_dereference_check() usage!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by strace/1365:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81077402>] do_wait+0xb2/0x370
>  #1: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff8801435dce20, at: [<ffffffff8107652d>] wait_consider_task+0x11d/0xf40
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff8107655a>] wait_consider_task+0x14a/0xf40
> 
> stack backtrace:
> Pid: 1365, comm: strace Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810765ec>] wait_consider_task+0x1dc/0xf40
>  [<ffffffff8107655a>] ? wait_consider_task+0x14a/0xf40
>  [<ffffffff810774d3>] do_wait+0x183/0x370
>  [<ffffffff81078d75>] sys_wait4+0x75/0xf0
>  [<ffffffff81075810>] ? task_stopped_code+0x60/0x60
>  [<ffffffff816ca088>] tracesys+0xe1/0xe6
> 
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.7.0-rc1+ #31 Not tainted
> -------------------------------
> include/linux/rcupdate.h:759 rcu_read_unlock() used illegally while idle!
> 
> other info that might help us debug this:
> 
> 
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 1
> RCU used illegally from extended quiescent state!
> 3 locks on stack by strace/1365:
>  #0: held:     (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff81077402>] do_wait+0xb2/0x370
>  #1: held:     (&(&sighand->siglock)->rlock){-.-.-.}, instance: ffff8801435dce20, at: [<ffffffff8107652d>] wait_consider_task+0x11d/0xf40
>  #2: blocked:  (rcu_read_lock){.+.+..}, instance: ffffffff81c34e80, at: [<ffffffff8107655a>] wait_consider_task+0x14a/0xf40
> 
> stack backtrace:
> Pid: 1365, comm: strace Not tainted 3.7.0-rc1+ #31
> Call Trace:
>  [<ffffffff810dfb22>] lockdep_rcu_suspicious+0xe2/0x130
>  [<ffffffff810769a5>] wait_consider_task+0x595/0xf40
>  [<ffffffff8107655a>] ? wait_consider_task+0x14a/0xf40
>  [<ffffffff810774d3>] do_wait+0x183/0x370
>  [<ffffffff81078d75>] sys_wait4+0x75/0xf0
>  [<ffffffff81075810>] ? task_stopped_code+0x60/0x60
>  [<ffffffff816ca088>] tracesys+0xe1/0xe6
> 
> --
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