Re: [PATCH 3/4] mm: Add free()

[Matthew Wilcox]

On Tue, Apr 03, 2018 at 10:50:59AM +0200, Pavel Machek wrote:
> > gcc already does some nice optimisations around free().  For example, it
> > can eliminate dead stores:
> 
> Are we comfortable with that optimalization for kernel?
> 
> us: "Hey, let's remove those encryption keys before freeing memory."
> gcc: :-).
> 
> us: "Hey, we want to erase lock magic values not to cause confusion
> later."
> gcc: "I like confusion!"
> 
> Yes, these probably can be fixed by strategic "volatile" and/or
> barriers, but...

Exactly, we should mark those sites explicitly with volatile so that 
they aren't dead stores.