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SubjectRe: 2.6.19-rc3-git7: scsi_device_unbusy: inconsistent lock state
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Date

> >
> >
> > [<c0219091>] cfq_set_request+0x351/0x3b0
> > [<c020c7fc>] elv_set_request+0x1c/0x40
> > [<c020fcff>] get_request+0x23f/0x270
> > [<c0210537>] get_request_wait+0x27/0x120
> > [<c02107ca>] __make_request+0x5a/0x350
> > [<c020f40f>] generic_make_request+0x16f/0x220
> > [<c02117e4>] submit_bio+0x64/0x110
> >
> > now cfq_set_request() uses several inlines which muddies the situation,
> > but lockdep claims one of them is not done correctly. (eg either it
> > takes the lock incorrectly or something does spin_unlock_irq while the
> > lock is held)
>
> It's not really inlined trickery, the trace is exactly as printed.

what I meant is that cfq_set_request() calls a few inlines that also
take locks so it might be one of those instead

> A few
> things may be allocated from that path, so we pass gfp_mask around. I'll
> double check it tonight, but I don't currently see what could be wrong.
> Would lockdep complain about:
>
> spin_lock_irqsave(lock, flags);
> ...
> spin_unlock_irq(lock);
> ...
> spin_lock_irq(lock);
> ...
> spin_unlock_irqrestore(lock, flags);

this is fine for lockdep IF and only IF there is no "out lock" held
around this that requires irqs to be off. So if you do

spin_lock_irqsave(lock1, flags);
...
spin_lock_irqsave(lock2, flags);
spin_unlock_irq(lock2)
...

then lockdep WILL complain, and rightfully so, about a violation since
lock1 gets violated here ;)


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