Re: [PATCH v2 tip/core/rcu 0/13] Miscellaneous fixes for 4.12

[Peter Zijlstra]

So the thing Maz complained about is because KVM assumes
synchronize_srcu() is 'free' when there is no srcu_read_lock() activity.
This series 'breaks' that.

I've not looked hard enough at the new SRCU to see if its possible to
re-instate that feature.