1 #ifndef PAGE_FLAGS_LAYOUT_H 2 #define PAGE_FLAGS_LAYOUT_H 3 4 #include <linux/numa.h> 5 #include <generated/bounds.h> 6 7 /* 8 * When a memory allocation must conform to specific limitations (such 9 * as being suitable for DMA) the caller will pass in hints to the 10 * allocator in the gfp_mask, in the zone modifier bits. These bits 11 * are used to select a priority ordered list of memory zones which 12 * match the requested limits. See gfp_zone() in include/linux/gfp.h 13 */ 14 #if MAX_NR_ZONES < 2 15 #define ZONES_SHIFT 0 16 #elif MAX_NR_ZONES <= 2 17 #define ZONES_SHIFT 1 18 #elif MAX_NR_ZONES <= 4 19 #define ZONES_SHIFT 2 20 #elif MAX_NR_ZONES <= 8 21 #define ZONES_SHIFT 3 22 #else 23 #error ZONES_SHIFT -- too many zones configured adjust calculation 24 #endif 25 26 #ifdef CONFIG_SPARSEMEM 27 #include <asm/sparsemem.h> 28 29 /* SECTION_SHIFT #bits space required to store a section # */ 30 #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) 31 32 #endif /* CONFIG_SPARSEMEM */ 33 34 /* 35 * page->flags layout: 36 * 37 * There are five possibilities for how page->flags get laid out. The first 38 * pair is for the normal case without sparsemem. The second pair is for 39 * sparsemem when there is plenty of space for node and section information. 40 * The last is when there is insufficient space in page->flags and a separate 41 * lookup is necessary. 42 * 43 * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | 44 * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS | 45 * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | 46 * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS | 47 * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | 48 */ 49 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) 50 #define SECTIONS_WIDTH SECTIONS_SHIFT 51 #else 52 #define SECTIONS_WIDTH 0 53 #endif 54 55 #define ZONES_WIDTH ZONES_SHIFT 56 57 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS 58 #define NODES_WIDTH NODES_SHIFT 59 #else 60 #ifdef CONFIG_SPARSEMEM_VMEMMAP 61 #error "Vmemmap: No space for nodes field in page flags" 62 #endif 63 #define NODES_WIDTH 0 64 #endif 65 66 #ifdef CONFIG_NUMA_BALANCING 67 #define LAST__PID_SHIFT 8 68 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) 69 70 #define LAST__CPU_SHIFT NR_CPUS_BITS 71 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) 72 73 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) 74 #else 75 #define LAST_CPUPID_SHIFT 0 76 #endif 77 78 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS 79 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT 80 #else 81 #define LAST_CPUPID_WIDTH 0 82 #endif 83 84 /* 85 * We are going to use the flags for the page to node mapping if its in 86 * there. This includes the case where there is no node, so it is implicit. 87 */ 88 #if !(NODES_WIDTH > 0 || NODES_SHIFT == 0) 89 #define NODE_NOT_IN_PAGE_FLAGS 90 #endif 91 92 #if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0 93 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS 94 #endif 95 96 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ 97