4d3702b6 (post-v2.6.26): WARNING: at kernel/lockdep.c:2731 check_flags (ftrace)

[Vegard Nossum]

Hi,

When booting 4d3702b6, I got this huge thing:

Testing tracer wakeup: <4>------------[ cut here ]------------
WARNING: at kernel/lockdep.c:2731 check_flags+0x123/0x160()
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.26-crashing-02127-g4d3702b6 #30
 [<c015c349>] warn_on_slowpath+0x59/0xb0
 [<c01276c6>] ? ftrace_call+0x5/0x8
 [<c012d800>] ? native_read_tsc+0x0/0x20
 [<c0158de2>] ? sub_preempt_count+0x12/0xf0
 [<c01814eb>] ? trace_hardirqs_off+0xb/0x10
 [<c0182fbc>] ? __lock_acquire+0x2cc/0x1120
 [<c01814eb>] ? trace_hardirqs_off+0xb/0x10
 [<c01276af>] ? mcount_call+0x5/0xa
 [<c017ff53>] check_flags+0x123/0x160
 [<c0183e61>] lock_acquire+0x51/0xd0
 [<c01276c6>] ? ftrace_call+0x5/0x8
 [<c0613d4f>] _spin_lock_irqsave+0x5f/0xa0
 [<c01a8d45>] ? ftrace_record_ip+0xf5/0x220
 [<c02d5413>] ? debug_locks_off+0x3/0x50
 [<c01a8d45>] ftrace_record_ip+0xf5/0x220
 [<c01276af>] mcount_call+0x5/0xa
 [<c02d5418>] ? debug_locks_off+0x8/0x50
 [<c017ff27>] check_flags+0xf7/0x160
 [<c0183e61>] lock_acquire+0x51/0xd0
 [<c01276c6>] ? ftrace_call+0x5/0x8
 [<c0613d4f>] _spin_lock_irqsave+0x5f/0xa0
 [<c01affcd>] ? wakeup_tracer_call+0x6d/0xf0
 [<c01625e2>] ? _local_bh_enable+0x62/0xb0
 [<c0158ddd>] ? sub_preempt_count+0xd/0xf0
 [<c01affcd>] wakeup_tracer_call+0x6d/0xf0
 [<c0162724>] ? __do_softirq+0xf4/0x110
 [<c01afff1>] ? wakeup_tracer_call+0x91/0xf0
 [<c01276c6>] ftrace_call+0x5/0x8
 [<c0162724>] ? __do_softirq+0xf4/0x110
 [<c0158de2>] ? sub_preempt_count+0x12/0xf0
 [<c01625e2>] _local_bh_enable+0x62/0xb0
 [<c0162724>] __do_softirq+0xf4/0x110
 [<c01627ed>] do_softirq+0xad/0xb0
 [<c0162a15>] irq_exit+0xa5/0xb0
 [<c013a506>] smp_apic_timer_interrupt+0x66/0xa0
 [<c02d3fac>] ? trace_hardirqs_off_thunk+0xc/0x10
 [<c0127449>] apic_timer_interrupt+0x2d/0x34
 [<c018007b>] ? find_usage_backwards+0xb/0xf0
 [<c0613a09>] ? _spin_unlock_irqrestore+0x69/0x80
 [<c014ef32>] tg_shares_up+0x132/0x1d0
 [<c014d2a2>] walk_tg_tree+0x62/0xa0
 [<c014ee00>] ? tg_shares_up+0x0/0x1d0
 [<c014a860>] ? tg_nop+0x0/0x10
 [<c015499d>] update_shares+0x5d/0x80
 [<c0154a2f>] try_to_wake_up+0x6f/0x280
 [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
 [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
 [<c0154c94>] wake_up_process+0x14/0x20
 [<c01725f6>] kthread_create+0x66/0xb0
 [<c0195400>] ? do_stop+0x0/0x200
 [<c0195320>] ? __stop_machine_run+0x30/0xb0
 [<c0195340>] __stop_machine_run+0x50/0xb0
 [<c0195400>] ? do_stop+0x0/0x200
 [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
 [<c061242d>] ? mutex_unlock+0xd/0x10
 [<c01953cc>] stop_machine_run+0x2c/0x60
 [<c01a94d3>] unregister_ftrace_function+0x103/0x180
 [<c01b0517>] stop_wakeup_tracer+0x17/0x60
 [<c01b056f>] wakeup_tracer_ctrl_update+0xf/0x30
 [<c01ab8d5>] trace_selftest_startup_wakeup+0xb5/0x130
 [<c01ab950>] ? trace_wakeup_test_thread+0x0/0x70
 [<c01aadf5>] register_tracer+0x135/0x1b0
 [<c0877d02>] init_wakeup_tracer+0xd/0xf
 [<c085d437>] kernel_init+0x1a9/0x2ce
 [<c061397b>] ? _spin_unlock_irq+0x3b/0x60
 [<c02d3f9c>] ? trace_hardirqs_on_thunk+0xc/0x10
 [<c0877cf5>] ? init_wakeup_tracer+0x0/0xf
 [<c0182646>] ? trace_hardirqs_on_caller+0x126/0x180
 [<c02d3f9c>] ? trace_hardirqs_on_thunk+0xc/0x10
 [<c01269c8>] ? restore_nocheck_notrace+0x0/0xe
 [<c085d28e>] ? kernel_init+0x0/0x2ce
 [<c085d28e>] ? kernel_init+0x0/0x2ce
 [<c01275fb>] kernel_thread_helper+0x7/0x10
 =======================
---[ end trace a7919e7f17c0a725 ]---
irq event stamp: 579530
hardirqs last  enabled at (579528): [<c01826ab>] trace_hardirqs_on+0xb/0x10
hardirqs last disabled at (579529): [<c01814eb>] trace_hardirqs_off+0xb/0x10
softirqs last  enabled at (579530): [<c0162724>] __do_softirq+0xf4/0x110
softirqs last disabled at (579517): [<c01627ed>] do_softirq+0xad/0xb0
irq event stamp: 579530
hardirqs last  enabled at (579528): [<c01826ab>] trace_hardirqs_on+0xb/0x10
hardirqs last disabled at (579529): [<c01814eb>] trace_hardirqs_off+0xb/0x10
softirqs last  enabled at (579530): [<c0162724>] __do_softirq+0xf4/0x110
softirqs last disabled at (579517): [<c01627ed>] do_softirq+0xad/0xb0
PASSED

Incidentally, the kernel also hung while I was typing in this report.

(I thought I'd already reported this in -next before the merge window
opened... weird.)


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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