name : page-flags-layout.h /* SPDX-License-Identifier: GPL-2.0 */ #ifndef PAGE_FLAGS_LAYOUT_H #define PAGE_FLAGS_LAYOUT_H #include <linux/numa.h> #include <generated/bounds.h> /* * When a memory allocation must conform to specific limitations (such * as being suitable for DMA) the caller will pass in hints to the * allocator in the gfp_mask, in the zone modifier bits. These bits * are used to select a priority ordered list of memory zones which * match the requested limits. See gfp_zone() in include/linux/gfp.h */ #if MAX_NR_ZONES < 2 #define ZONES_SHIFT 0 #elif MAX_NR_ZONES <= 2 #define ZONES_SHIFT 1 #elif MAX_NR_ZONES <= 4 #define ZONES_SHIFT 2 #elif MAX_NR_ZONES <= 8 #define ZONES_SHIFT 3 #else #error ZONES_SHIFT "Too many zones configured" #endif #define ZONES_WIDTH ZONES_SHIFT #ifdef CONFIG_SPARSEMEM #include <asm/sparsemem.h> #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) #else #define SECTIONS_SHIFT 0 #endif #ifndef BUILD_VDSO32_64 /* * page->flags layout: * * There are five possibilities for how page->flags get laid out. The first * pair is for the normal case without sparsemem. The second pair is for * sparsemem when there is plenty of space for node and section information. * The last is when there is insufficient space in page->flags and a separate * lookup is necessary. * * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS | * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS | * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | */ #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTIONS_WIDTH SECTIONS_SHIFT #else #define SECTIONS_WIDTH 0 #endif #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \ <= BITS_PER_LONG - NR_PAGEFLAGS #define NODES_WIDTH NODES_SHIFT #elif defined(CONFIG_SPARSEMEM_VMEMMAP) #error "Vmemmap: No space for nodes field in page flags" #else #define NODES_WIDTH 0 #endif /* * Note that this #define MUST have a value so that it can be tested with * the IS_ENABLED() macro. */ #if NODES_SHIFT != 0 && NODES_WIDTH == 0 #define NODE_NOT_IN_PAGE_FLAGS 1 #endif #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) #define KASAN_TAG_WIDTH 8 #else #define KASAN_TAG_WIDTH 0 #endif #ifdef CONFIG_NUMA_BALANCING #define LAST__PID_SHIFT 8 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) #define LAST__CPU_SHIFT NR_CPUS_BITS #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) #else #define LAST_CPUPID_SHIFT 0 #endif #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT #else #define LAST_CPUPID_WIDTH 0 #endif #if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS #endif #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS #error "Not enough bits in page flags" #endif /* see the comment on MAX_NR_TIERS */ #define LRU_REFS_WIDTH min(__LRU_REFS_WIDTH, BITS_PER_LONG - NR_PAGEFLAGS - \ ZONES_WIDTH - LRU_GEN_WIDTH - SECTIONS_WIDTH - \ NODES_WIDTH - KASAN_TAG_WIDTH - LAST_CPUPID_WIDTH) #endif #endif /* _LINUX_PAGE_FLAGS_LAYOUT */