Re: [PATCH 1/2] slab: __GFP_ZERO is incompatible with a constructor

[Christopher Lameter]

On Tue, 10 Apr 2018, Matthew Wilcox wrote:

> > How do you envision dealing with the SLAB_TYPESAFE_BY_RCU slab caches?
> > Those must have a defined state of the objects at all times and a constructor is
> > required for that. And their use of RCU is required for numerous lockless
> > lookup algorithms in the kernhel.
>
> Not at all times.  Only once they've been used.  Re-constructing them
> once they've been used might break the rcu typesafety, I suppose ...
> would need to examine the callers.

Objects can be freed and reused and still be accessed from code that
thinks the object is the old and not the new object....