Re: [patch for-3.14] mm, mempolicy: fix mempolicy printing innuma_maps

From: David Rientjes
Date: Mon Jan 27 2014 - 18:31:47 EST


On Mon, 27 Jan 2014, Mel Gorman wrote:

> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index c2ccec0..c1a2573 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -120,6 +120,14 @@ static struct mempolicy default_policy = {
>
> static struct mempolicy preferred_node_policy[MAX_NUMNODES];
>
> +/* Returns true if the policy is the default policy */
> +static bool mpol_is_default(struct mempolicy *pol)
> +{
> + return !pol ||
> + pol == &default_policy ||
> + pol == &preferred_node_policy[numa_node_id()];
> +}
> +
> static struct mempolicy *get_task_policy(struct task_struct *p)
> {
> struct mempolicy *pol = p->mempolicy;

I was trying to avoid doing this because numa_node_id() of process A
reading numa_maps for process B has nothing to do with the policy of the
process A and I thought MPOL_F_MORON's purpose was exactly for what it is
used for today. It works today since you initialize preferred_node_policy
for all nodes, but could this ever change to only be valid for N_MEMORY
node states, for example?

I'm not sure what the harm in updating mpol_to_str() would be if
MPOL_F_MORON is to change in the future?
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