From: Christoph Lameter The __GFP_xx definitions in include/linux/gfp.h are used to refer to individual bits in the GFP bitmasks. I think they should not be conditional via ifdef. If a conditional definition is required then a version without the underscore should be used. My patch from yesterday cleared up the definitions that resulted in zero values. This one removes the #ifdef around __GFP_DMA32. The x86_64 arch code is the only user of __GFP_DMA32 and x86_64 sets CONFIG_ZONE_DMA32. No driver is using DMA32. So we do not really need fall back behavior for ZONE_DMA32 at this point. If ZONE_DMA32 would be used by a device driver in the future on a platform that has not set CONFIG_ZONE_DMA32 then we will fall back to ZONE_NORMAL because the __GFP_DMA32 bit is not set in GFP_ZONEMASK. I think if different behavior is desired then the device driver would have to take care of falling back to a different allocation. The absence of DMA32 slab support may already force the device driver to deal with this case anyways. Another solution would be to make the definition of GFP_DMA32 conditional on CONFIG_ZONE_DMA32 and 32/64 bit. That would leave the __GFP_xx untouched. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton --- include/linux/gfp.h | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff -puN include/linux/gfp.h~reduce-max_nr_zones-make-zone_highmem-optional-fix-fix include/linux/gfp.h --- a/include/linux/gfp.h~reduce-max_nr_zones-make-zone_highmem-optional-fix-fix +++ a/include/linux/gfp.h @@ -9,16 +9,19 @@ struct vm_area_struct; /* * GFP bitmasks.. + * + * Zone modifiers (see linux/mmzone.h - low three bits) + * + * These may be masked by GFP_ZONEMASK to make allocations with this bit + * set fall back to ZONE_NORMAL. + * + * Do not put any conditional on these. If necessary modify the definitions + * without the underscores and use the consistently. The definitions here may + * be used in bit comparisons. */ -/* Zone modifiers in GFP_ZONEMASK (see linux/mmzone.h - low three bits) */ #define __GFP_DMA ((__force gfp_t)0x01u) #define __GFP_HIGHMEM ((__force gfp_t)0x02u) - -#if !defined(CONFIG_ZONE_DMA32) && BITS_PER_LONG >= 64 -#define __GFP_DMA32 ((__force gfp_t)0x01) /* ZONE_DMA is ZONE_DMA32 */ -#else -#define __GFP_DMA32 ((__force gfp_t)0x04) /* Has own ZONE_DMA32 */ -#endif +#define __GFP_DMA32 ((__force gfp_t)0x04u) /* * Action modifiers - doesn't change the zoning _