On Tue, 31 Jul 2018, Dmitry Vyukov wrote:

quoted

Actually you should do this for SLAB_TYPESAFE_BY_RCU slabs. Usually they are with ->ctors but there
are few without constructors.
We can't reinitialize or even retag them. The latter will definitely cause false-positive use-after-free reports.

Somewhat offtopic, but I can't understand how SLAB_TYPESAFE_BY_RCU
slabs can be useful without ctors or at least memset(0). Objects in
such slabs need to be type-stable, but I can't understand how it's
possible to establish type stability without a ctor... Are these bugs?
Or I am missing something subtle? What would be a canonical usage of
SLAB_TYPESAFE_BY_RCU slab without a ctor?

True that sounds fishy. Would someone post a list of SLAB_TYPESAFE_BY_RCU
slabs without ctors?