Re: [PATCH 1/11] Add __GFP_MOVABLE flag and update callers

From: Christoph Lameter
Date: Tue Nov 21 2006 - 21:25:42 EST


On Tue, 21 Nov 2006, Mel Gorman wrote:

> On Tue, 21 Nov 2006, Christoph Lameter wrote:
>
> > Are GFP_HIGHUSER allocations always movable? It would reduce the size of
> > the patch if this would be added to GFP_HIGHUSER.
> No, they aren't. Page tables allocated with HIGHPTE are currently not movable
> for example. A number of drivers (infiniband for example) also use
> __GFP_HIGHMEM that are not movable.

HIGHPTE with __GFP_USER set? This is a page table page right?
pte_alloc_one does currently not set GFP_USER:

struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *pte;

#ifdef CONFIG_HIGHPTE
pte =
alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
#else
pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
#endif
return pte;
}

How does infiniband insure that page migration does not move those pages?

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