On Tue, 6 Nov 2012, Hugh Dickins wrote:

Ah, now I actually scan through it, I see references to blank screen:
I'll try taking off your patch and seeing if it came up at screen
blanking time, then put on your patch back on and try again.
I'll report back in an hour or two.

Yes, that was it.  When the console screen blanked on 3.7.0-rc3-mm1,
it generated that lockdep splat, visible once I unblanked.  But once I
applied your patch to the kernel, lockdep kept quiet across blank/unblank.

Thanks!
Hugh