Comment 16 for bug 1156138

I'll weigh in here: I maintain the corresponding driver for ArchLinux; at Arch, the default kernel is pretty much "plain vanilla", and it suffers from this very same problem, since CONFIG_PREEMPT_RCU is on by default.
I've been hoping for a resolution to this problem since March, as it has affected Arch since kernel 3.8 and the changes it prompted to this driver at that time (introducing the calls to rcu_read_lock/unlock in the driver).

For a while, I was under the impression that this problem had been fixed for Ubuntu / low latency, and had been scratching my head to find out how, but I guess I am on the wrong track: it is still a problem on Ubuntu as well.