-tip: WARNING: at kernel/lockdep.c:2738

[Vegard Nossum]

Hi,

I just got this on the latest tip/master shortly after finishing initcalls:

------------[ cut here ]------------
WARNING: at kernel/lockdep.c:2738 check_flags+0x142/0x160()
Pid: 5, comm: watchdog/0 Not tainted 2.6.26-rc8-tip-00206-g3248a70-dirty #49
 [<c0139684>] warn_on_slowpath+0x54/0x70
 [<c015be00>] ? trace_hardirqs_off_caller+0x40/0xe0
 [<c010a7c5>] ? native_sched_clock+0xb5/0x110
 [<c018076e>] ? ftrace_record_ip+0x12e/0x240
 [<c05ab8c8>] ? _spin_unlock_irqrestore+0x48/0x80
 [<c029ffd3>] ? debug_locks_off+0x3/0x50
 [<c018076e>] ? ftrace_record_ip+0x12e/0x240
 [<c0104f6b>] ? mcount_call+0x5/0xa
 [<c015b322>] check_flags+0x142/0x160
 [<c015f6e9>] lock_acquire+0x59/0xd0
 [<c01769f1>] ? watchdog+0xb1/0x1e0
 [<c05ab2fd>] _read_lock+0x3d/0x70
 [<c01769f1>] ? watchdog+0xb1/0x1e0
 [<c01769f1>] watchdog+0xb1/0x1e0
 [<c05ab8c8>] ? _spin_unlock_irqrestore+0x48/0x80
 [<c012bae9>] ? complete+0x49/0x60
 [<c0176940>] ? watchdog+0x0/0x1e0
 [<c014e637>] kthread+0x47/0x80
 [<c014e5f0>] ? kthread+0x0/0x80
 [<c0104f53>] kernel_thread_helper+0x7/0x10
 =======================
---[ end trace 8e23f95b45fa05f7 ]---
possible reason: unannotated irqs-on.
irq event stamp: 18
hardirqs last  enabled at (17): [<c015e02b>] trace_hardirqs_on+0xb/0x10
hardirqs last disabled at (18): [<c015beab>] trace_hardirqs_off+0xb/0x10
softirqs last  enabled at (0): [<c0137cd8>] copy_process+0x268/0x10b0
softirqs last disabled at (0): [<00000000>] 0x0

I hope this wasn't caused by any of my patches :-S

$ addr2line -e vmlinux -i c01769f1
kernel/softlockup.c:232
kernel/softlockup.c:271

It seems that Andrew reported this too,
http://lkml.org/lkml/2008/6/9/41, but I already have the fix,

commit 040ec23d07f95285e9777a85cda29cb339a3065b
Author: Ingo Molnar <mingo@xxxxxxx>
Date:   Mon Jun 9 01:45:29 2008 -0700

    sched: sched_clock() lockdep fix

so it can't be the same one.

(It seems to be something ftrace-related, adding Steven to Cc.)


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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