It's quite likely that this is yet another manifestation of bug #541511. This is being worked on upstream, and it seems like there's something approximating a fix that should get applied to the upstream kernel in the next couple of weeks.
It's quite likely that this is yet another manifestation of bug #541511. This is being worked on upstream, and it seems like there's something approximating a fix that should get applied to the upstream kernel in the next couple of weeks.