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Message-ID: <6599ad830612080851q55fe8c95m9f00a2a9a3779dc4@mail.gmail.com>
Date: Fri, 8 Dec 2006 08:51:01 -0800
From: "Paul Menage" <menage@google.com>
To: "Paul Jackson" <pj@sgi.com>
Subject: Re: [PATCH] cpuset - rework cpuset_zone_allowed api
Cc: "Andrew Morton" <akpm@osdl.org>, linux-kernel@vger.kernel.org,
       "Nick Piggin" <nickpiggin@yahoo.com.au>, "Andi Kleen" <ak@suse.de>,
       "Christoph Lameter" <clameter@sgi.com>
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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