Re: [PATCH v5] futex: Remove requirement for lock_page in get_futex_key

[Thomas Gleixner]

On Wed, 3 Feb 2016, Davidlohr Bueso wrote:
> +		 * We are not calling into get_futex_key_refs() in file-backed
> +		 * cases, therefore a successful atomic_inc return below will
> +		 * guarantee that get_futex_key() will continue to imply MB (B).

Can you please make that "MB (B)" part a bit more outstanding. I really had to
search for it.

> +		 */
> +		if (WARN_ON_ONCE(!atomic_inc_not_zero(&inode->i_count))) {
> +			rcu_read_unlock();
> +			put_page(page);
> +
> +			goto again;
> +		}

Don't we need 

		smp_mb__after_atomic();

here to make it a full barrier on all architectures?

Thanks,

	tglx