What does inconsistent lock state mean?

[Kai Meyer]

I'm getting this when I try to spin_unlock a recently acquired lock with 
spin_lock. IRQs are still somewhat of a mystery to me, and cryptic lock 
state symbols (IN-HARDIRQ-W, HARDIRQ-ON-W) are unintelligible to me.

Dec  7 15:52:20 dev2 kernel: =================================
Dec  7 15:52:20 dev2 kernel: [ INFO: inconsistent lock state ]
Dec  7 15:52:20 dev2 kernel: 2.6.32-220.el6.x86_64.debug #1
Dec  7 15:52:20 dev2 kernel: ---------------------------------
Dec  7 15:52:20 dev2 kernel: inconsistent {IN-HARDIRQ-W} -> 
{HARDIRQ-ON-W} usage.

Looking at lockdep.c isn't giving me any help either. It's obfuscated 
beyond my ability to grok by simply reading the code.

It seems like this portion should help me, but it doesn't....
Dec  7 15:52:20 dev2 kernel: {IN-HARDIRQ-W} state was registered at:
Dec  7 15:52:20 dev2 kernel:  [<ffffffff810afbca>] 
__lock_acquire+0x77a/0x1570
Dec  7 15:52:20 dev2 kernel:  [<ffffffff810b0a64>] lock_acquire+0xa4/0x120
Dec  7 15:52:20 dev2 kernel:  [<ffffffff81520c75>] 
_spin_lock_irqsave+0x55/0xa0
Dec  7 15:52:20 dev2 kernel:  [<ffffffffa006b19b>] blk_done+0x2b/0x110 
[virtio_blk]
Dec  7 15:52:20 dev2 kernel:  [<ffffffffa00401dc>] 
vring_interrupt+0x3c/0xd0 [virtio_ring]
Dec  7 15:52:20 dev2 kernel:  [<ffffffff810ec080>] 
handle_IRQ_event+0x50/0x160
Dec  7 15:52:20 dev2 kernel:  [<ffffffff810ee840>] 
handle_edge_irq+0xe0/0x170
Dec  7 15:52:20 dev2 kernel:  [<ffffffff8100e059>] handle_irq+0x49/0xa0
Dec  7 15:52:20 dev2 kernel:  [<ffffffff81526cdc>] do_IRQ+0x6c/0xf0
Dec  7 15:52:20 dev2 kernel:  [<ffffffff8100ba93>] ret_from_intr+0x0/0x16
Dec  7 15:52:20 dev2 kernel:  [<ffffffff810148e2>] default_idle+0x52/0xc0
Dec  7 15:52:20 dev2 kernel:  [<ffffffff81009e0b>] cpu_idle+0xbb/0x110
Dec  7 15:52:20 dev2 kernel:  [<ffffffff81516623>] 
start_secondary+0x211/0x254

Then later it tells me that I'm holding 1 lock, which is the one that I 
mentioned at the beginning that was just recently locked.