Re: [PATCH] cpuset - rework cpuset_zone_allowed api

["Paul Menage" <menage@google.com>]

On 12/8/06, Paul Jackson <pj@sgi.com> wrote:
>
> -int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
> +int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
>  {
>         int node;                       /* node that zone z is on */
>         const struct cpuset *cs;        /* current cpuset ancestors */
> @@ -2335,6 +2351,40 @@ int __cpuset_zone_allowed(struct zone *z
>         return allowed;
>  }

While you're changing this, is there a good reason not to check
is_mem_exclusive() *before* taking callback_mutex and calling
nearest_exclusive_ancestor()?

something like:

rcu_read_lock();
exc = is_mem_exclusive(rcu_dereference(current->cs));
rcu_read_unlock();
if (exc)
  return 1;

... take callback_mutex, etc ...

Paul