On Sat, Jun 1, 2019 at 10:56 PM Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> You can't then go and decide to remove the compiler barrier!  To do
> that you'd need to audit every single use of rcu_read_lock in the
> kernel to ensure that they're not depending on the compiler barrier.

What's the possible case where it would matter when there is no preemption?

          Linus