On Tue, 5 Feb 2008, Lee Schermerhorn wrote:

> mbind(2), on the other hand, just masks off any nodes in the 
> nodemask that are not included in the caller's mems_allowed.

Ok so we temporarily adopt these semantics for set_mempolicy.

> 1) modify contextualize_policy to just remove the non-allowed
>    nodes, as is currently done in-line for mbind().  This
>    guarantees that the resulting mask includes only nodes with
>    memory.

Right make ssense. we already contextualize for cpusets.

> Index: Linux/mm/mempolicy.c
> ===================================================================
> --- Linux.orig/mm/mempolicy.c 2008-02-05 11:25:17.000000000 -0500
> +++ Linux/mm/mempolicy.c      2008-02-05 16:03:11.000000000 -0500
> @@ -131,7 +131,7 @@ static int mpol_check_policy(int mode, n
>                       return -EINVAL;
>               break;
>       }
> -     return nodes_subset(*nodes, node_states[N_HIGH_MEMORY]) ? 0 : -EINVAL;
> +     return 0;
>  }

Hmmm... That is a pretty drastic change.

> @@ -188,8 +188,6 @@ static struct mempolicy *mpol_new(int mo
>       switch (mode) {
>       case MPOL_INTERLEAVE:
>               policy->v.nodes = *nodes;
> -             nodes_and(policy->v.nodes, policy->v.nodes,
> -                                     node_states[N_HIGH_MEMORY]);
>               if (nodes_weight(policy->v.nodes) == 0) {
>                       kmem_cache_free(policy_cache, policy);
>                       return ERR_PTR(-EINVAL);

Do we really need to remove these lines if we change set_mempolicy?

> @@ -426,9 +424,13 @@ static int contextualize_policy(int mode
>       if (!nodes)
>               return 0;
>  
> +     /*
> +      * Restrict the nodes to the allowed nodes in the cpuset.
> +      * This is guaranteed to be a subset of nodes with memory.
> +      */
>       cpuset_update_task_memory_state();
> -     if (!cpuset_nodes_subset_current_mems_allowed(*nodes))
> -             return -EINVAL;
> +     nodes_and(*nodes, *nodes, cpuset_current_mems_allowed);
> +
>       return mpol_check_policy(mode, nodes);
>  }
>  

Ditto?

> @@ -797,7 +799,7 @@ static long do_mbind(unsigned long start
>       if (end == start)
>               return 0;
>  
> -     if (mpol_check_policy(mode, nmask))
> +     if (contextualize_policy(mode, nmask))
>               return -EINVAL;
>  
>       new = mpol_new(mode, nmask);
> @@ -915,10 +917,6 @@ asmlinkage long sys_mbind(unsigned long 
>       err = get_nodes(&nodes, nmask, maxnode);
>       if (err)
>               return err;
> -#ifdef CONFIG_CPUSETS
> -     /* Restrict the nodes to the allowed nodes in the cpuset */
> -     nodes_and(nodes, nodes, current->mems_allowed);
> -#endif

Would just removing #ifdef CONFIG_CPUSETS work? mems_allowed falls back to 
node_possible_map.... Shouldnt that be node_online_map?

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