Re: [PATCH] mempolicy:add GFP_THISNODE when allocing new page

[Christoph Lameter <cl@linux-foundation.org>]

On Fri, 16 Apr 2010, Bob Liu wrote:

> Hmm.
> What about this change? If the from_nodes and to_nodes' weight is different,
> then we can don't preserv of the relative position of the page to the beginning
> of the node set. This case if a page allocation from the dest node
> failed, it will
> be allocated from the next node instead of early return.

Understand what you are doing first. The fallback is already there.

> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 08f40a2..094d092 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -842,7 +842,8 @@ static void migrate_page_add(struct page *page,
> struct list_head *pagelist,
>
>  static struct page *new_node_page(struct page *page, unsigned long
> node, int **x)
>  {
> -       return alloc_pages_exact_node(node, GFP_HIGHUSER_MOVABLE, 0);
> +       return alloc_pages_exact_node(node,
> +                       GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);

You eliminate falling back to the next node?

GFP_THISNODE forces allocation from the node. Without it we will fallback.

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