Re: [kernel-hardening] [PATCH] arm: kernel: implement fast refcount checking

[Ard Biesheuvel]

On 3 January 2018 at 13:36, Jinbum Park <jinb.park7@xxxxxxxxx> wrote:
>>> This is a nice result. However, without any insight into the presence
>>> of actual refcount hot spots, it is not obvious that we need this
>>> patch. This is the reason we ended up enabling CONFIG_REFCOUNT_FULL
>>> for arm64. I will let others comment on whether we want this patch in
>>> the first place,
>
> Dear Ard, Dave,
>
> I wanna hear some comment on above point.
> Is CONFIG_REFCOUNT_FULL much better for arm?
> If it is, I don't need to prepare v2 patch. (then, just needed to add
> "select REFCOUNT_FULL")
>

Well, we should probably turn that around. Please use REFCOUNT_FULL,
until you run into a use case where the slowdown is noticeable. If
nobody ever notices, we don't need to fix anything.