Sparsemem vmemmap does not need any section bits. This patch has the effect of reducing the number of bits used in page->flags by at least 6. Signed-off-by: Christoph Lameter --- include/linux/mm.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h 2008-03-03 15:45:07.047305876 -0800 +++ linux-2.6/include/linux/mm.h 2008-03-03 15:49:04.686432973 -0800 @@ -390,11 +390,11 @@ static inline void set_compound_order(st * we have run out of space and have to fall back to an * alternate (slower) way of determining the node. * - * No sparsemem: | NODE | ZONE | ... | FLAGS | - * with space for node: | SECTION | NODE | ZONE | ... | FLAGS | - * no space for node: | SECTION | ZONE | ... | FLAGS | + * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | + * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | + * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | */ -#ifdef CONFIG_SPARSEMEM +#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTIONS_WIDTH SECTIONS_SHIFT #else #define SECTIONS_WIDTH 0 @@ -405,6 +405,9 @@ static inline void set_compound_order(st #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= FLAGS_RESERVED #define NODES_WIDTH NODES_SHIFT #else +#ifdef CONFIG_SPARSEMEM_VMEMMAP +#error "Vmemmap: No space for nodes field in page flags" +#endif #define NODES_WIDTH 0 #endif -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/