DMA32 zone unusable

DMA32 zone unusable

[Mika Penttilä]

The new DMA32 zone (which at least x86-64 has) is quite "interesting" :

#define __GFP_DMA32    ((__force gfp_t)0x04) <-----!!!!!  

#define GFP_ZONEMASK    0x03   <------!!!!!

#define gfp_zone(mask) ((__force int)((mask) & (__force gfp_t)GFP_ZONEMASK))

static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
                        unsigned int order)
{
    if (unlikely(order >= MAX_ORDER))
        return NULL;

    return __alloc_pages(gfp_mask, order,
        NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
}


So with GFP_DMA32 you never get those pages (but DMA instead).

--Mika

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Re: DMA32 zone unusable

[Andi Kleen]

On Wednesday 16 November 2005 16:22, Mika Penttila wrote:
> The new DMA32 zone (which at least x86-64 has) is quite "interesting" :
> 
> #define __GFP_DMA32    ((__force gfp_t)0x04) <-----!!!!!  
> 
> #define GFP_ZONEMASK    0x03   <------!!!!!
> 
> #define gfp_zone(mask) ((__force int)((mask) & (__force gfp_t)GFP_ZONEMASK))

Yes that was a last minute change that was wrong. I will submit
an update. Thanks for reviewing.

-Andi

> static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
>                         unsigned int order)
> {
>     if (unlikely(order >= MAX_ORDER))
>         return NULL;
> 
>     return __alloc_pages(gfp_mask, order,
>         NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
> }
> 
> 
> So with GFP_DMA32 you never get those pages (but DMA instead).
> 
> --Mika
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
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