linux/include/linux/mm_types.h
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   1#ifndef _LINUX_MM_TYPES_H
   2#define _LINUX_MM_TYPES_H
   3
   4#include <linux/auxvec.h>
   5#include <linux/types.h>
   6#include <linux/threads.h>
   7#include <linux/list.h>
   8#include <linux/spinlock.h>
   9#include <linux/rbtree.h>
  10#include <linux/rwsem.h>
  11#include <linux/completion.h>
  12#include <linux/cpumask.h>
  13#include <linux/page-debug-flags.h>
  14#include <linux/uprobes.h>
  15#include <asm/page.h>
  16#include <asm/mmu.h>
  17
  18#ifndef AT_VECTOR_SIZE_ARCH
  19#define AT_VECTOR_SIZE_ARCH 0
  20#endif
  21#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
  22
  23struct address_space;
  24
  25#define USE_SPLIT_PTLOCKS       (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
  26
  27/*
  28 * Each physical page in the system has a struct page associated with
  29 * it to keep track of whatever it is we are using the page for at the
  30 * moment. Note that we have no way to track which tasks are using
  31 * a page, though if it is a pagecache page, rmap structures can tell us
  32 * who is mapping it.
  33 *
  34 * The objects in struct page are organized in double word blocks in
  35 * order to allows us to use atomic double word operations on portions
  36 * of struct page. That is currently only used by slub but the arrangement
  37 * allows the use of atomic double word operations on the flags/mapping
  38 * and lru list pointers also.
  39 */
  40struct page {
  41        /* First double word block */
  42        unsigned long flags;            /* Atomic flags, some possibly
  43                                         * updated asynchronously */
  44        struct address_space *mapping;  /* If low bit clear, points to
  45                                         * inode address_space, or NULL.
  46                                         * If page mapped as anonymous
  47                                         * memory, low bit is set, and
  48                                         * it points to anon_vma object:
  49                                         * see PAGE_MAPPING_ANON below.
  50                                         */
  51        /* Second double word */
  52        struct {
  53                union {
  54                        pgoff_t index;          /* Our offset within mapping. */
  55                        void *freelist;         /* slub/slob first free object */
  56                        bool pfmemalloc;        /* If set by the page allocator,
  57                                                 * ALLOC_NO_WATERMARKS was set
  58                                                 * and the low watermark was not
  59                                                 * met implying that the system
  60                                                 * is under some pressure. The
  61                                                 * caller should try ensure
  62                                                 * this page is only used to
  63                                                 * free other pages.
  64                                                 */
  65                };
  66
  67                union {
  68#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
  69        defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
  70                        /* Used for cmpxchg_double in slub */
  71                        unsigned long counters;
  72#else
  73                        /*
  74                         * Keep _count separate from slub cmpxchg_double data.
  75                         * As the rest of the double word is protected by
  76                         * slab_lock but _count is not.
  77                         */
  78                        unsigned counters;
  79#endif
  80
  81                        struct {
  82
  83                                union {
  84                                        /*
  85                                         * Count of ptes mapped in
  86                                         * mms, to show when page is
  87                                         * mapped & limit reverse map
  88                                         * searches.
  89                                         *
  90                                         * Used also for tail pages
  91                                         * refcounting instead of
  92                                         * _count. Tail pages cannot
  93                                         * be mapped and keeping the
  94                                         * tail page _count zero at
  95                                         * all times guarantees
  96                                         * get_page_unless_zero() will
  97                                         * never succeed on tail
  98                                         * pages.
  99                                         */
 100                                        atomic_t _mapcount;
 101
 102                                        struct { /* SLUB */
 103                                                unsigned inuse:16;
 104                                                unsigned objects:15;
 105                                                unsigned frozen:1;
 106                                        };
 107                                        int units;      /* SLOB */
 108                                };
 109                                atomic_t _count;                /* Usage count, see below. */
 110                        };
 111                };
 112        };
 113
 114        /* Third double word block */
 115        union {
 116                struct list_head lru;   /* Pageout list, eg. active_list
 117                                         * protected by zone->lru_lock !
 118                                         */
 119                struct {                /* slub per cpu partial pages */
 120                        struct page *next;      /* Next partial slab */
 121#ifdef CONFIG_64BIT
 122                        int pages;      /* Nr of partial slabs left */
 123                        int pobjects;   /* Approximate # of objects */
 124#else
 125                        short int pages;
 126                        short int pobjects;
 127#endif
 128                };
 129
 130                struct list_head list;  /* slobs list of pages */
 131                struct {                /* slab fields */
 132                        struct kmem_cache *slab_cache;
 133                        struct slab *slab_page;
 134                };
 135        };
 136
 137        /* Remainder is not double word aligned */
 138        union {
 139                unsigned long private;          /* Mapping-private opaque data:
 140                                                 * usually used for buffer_heads
 141                                                 * if PagePrivate set; used for
 142                                                 * swp_entry_t if PageSwapCache;
 143                                                 * indicates order in the buddy
 144                                                 * system if PG_buddy is set.
 145                                                 */
 146#if USE_SPLIT_PTLOCKS
 147                spinlock_t ptl;
 148#endif
 149                struct kmem_cache *slab;        /* SLUB: Pointer to slab */
 150                struct page *first_page;        /* Compound tail pages */
 151        };
 152
 153        /*
 154         * On machines where all RAM is mapped into kernel address space,
 155         * we can simply calculate the virtual address. On machines with
 156         * highmem some memory is mapped into kernel virtual memory
 157         * dynamically, so we need a place to store that address.
 158         * Note that this field could be 16 bits on x86 ... ;)
 159         *
 160         * Architectures with slow multiplication can define
 161         * WANT_PAGE_VIRTUAL in asm/page.h
 162         */
 163#if defined(WANT_PAGE_VIRTUAL)
 164        void *virtual;                  /* Kernel virtual address (NULL if
 165                                           not kmapped, ie. highmem) */
 166#endif /* WANT_PAGE_VIRTUAL */
 167#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
 168        unsigned long debug_flags;      /* Use atomic bitops on this */
 169#endif
 170
 171#ifdef CONFIG_KMEMCHECK
 172        /*
 173         * kmemcheck wants to track the status of each byte in a page; this
 174         * is a pointer to such a status block. NULL if not tracked.
 175         */
 176        void *shadow;
 177#endif
 178}
 179/*
 180 * The struct page can be forced to be double word aligned so that atomic ops
 181 * on double words work. The SLUB allocator can make use of such a feature.
 182 */
 183#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
 184        __aligned(2 * sizeof(unsigned long))
 185#endif
 186;
 187
 188struct page_frag {
 189        struct page *page;
 190#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
 191        __u32 offset;
 192        __u32 size;
 193#else
 194        __u16 offset;
 195        __u16 size;
 196#endif
 197};
 198
 199typedef unsigned long __nocast vm_flags_t;
 200
 201/*
 202 * A region containing a mapping of a non-memory backed file under NOMMU
 203 * conditions.  These are held in a global tree and are pinned by the VMAs that
 204 * map parts of them.
 205 */
 206struct vm_region {
 207        struct rb_node  vm_rb;          /* link in global region tree */
 208        vm_flags_t      vm_flags;       /* VMA vm_flags */
 209        unsigned long   vm_start;       /* start address of region */
 210        unsigned long   vm_end;         /* region initialised to here */
 211        unsigned long   vm_top;         /* region allocated to here */
 212        unsigned long   vm_pgoff;       /* the offset in vm_file corresponding to vm_start */
 213        struct file     *vm_file;       /* the backing file or NULL */
 214
 215        int             vm_usage;       /* region usage count (access under nommu_region_sem) */
 216        bool            vm_icache_flushed : 1; /* true if the icache has been flushed for
 217                                                * this region */
 218};
 219
 220/*
 221 * This struct defines a memory VMM memory area. There is one of these
 222 * per VM-area/task.  A VM area is any part of the process virtual memory
 223 * space that has a special rule for the page-fault handlers (ie a shared
 224 * library, the executable area etc).
 225 */
 226struct vm_area_struct {
 227        struct mm_struct * vm_mm;       /* The address space we belong to. */
 228        unsigned long vm_start;         /* Our start address within vm_mm. */
 229        unsigned long vm_end;           /* The first byte after our end address
 230                                           within vm_mm. */
 231
 232        /* linked list of VM areas per task, sorted by address */
 233        struct vm_area_struct *vm_next, *vm_prev;
 234
 235        pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
 236        unsigned long vm_flags;         /* Flags, see mm.h. */
 237
 238        struct rb_node vm_rb;
 239
 240        /*
 241         * For areas with an address space and backing store,
 242         * linkage into the address_space->i_mmap interval tree, or
 243         * linkage of vma in the address_space->i_mmap_nonlinear list.
 244         */
 245        union {
 246                struct {
 247                        struct rb_node rb;
 248                        unsigned long rb_subtree_last;
 249                } linear;
 250                struct list_head nonlinear;
 251        } shared;
 252
 253        /*
 254         * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
 255         * list, after a COW of one of the file pages.  A MAP_SHARED vma
 256         * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
 257         * or brk vma (with NULL file) can only be in an anon_vma list.
 258         */
 259        struct list_head anon_vma_chain; /* Serialized by mmap_sem &
 260                                          * page_table_lock */
 261        struct anon_vma *anon_vma;      /* Serialized by page_table_lock */
 262
 263        /* Function pointers to deal with this struct. */
 264        const struct vm_operations_struct *vm_ops;
 265
 266        /* Information about our backing store: */
 267        unsigned long vm_pgoff;         /* Offset (within vm_file) in PAGE_SIZE
 268                                           units, *not* PAGE_CACHE_SIZE */
 269        struct file * vm_file;          /* File we map to (can be NULL). */
 270        void * vm_private_data;         /* was vm_pte (shared mem) */
 271
 272#ifndef CONFIG_MMU
 273        struct vm_region *vm_region;    /* NOMMU mapping region */
 274#endif
 275#ifdef CONFIG_NUMA
 276        struct mempolicy *vm_policy;    /* NUMA policy for the VMA */
 277#endif
 278};
 279
 280struct core_thread {
 281        struct task_struct *task;
 282        struct core_thread *next;
 283};
 284
 285struct core_state {
 286        atomic_t nr_threads;
 287        struct core_thread dumper;
 288        struct completion startup;
 289};
 290
 291enum {
 292        MM_FILEPAGES,
 293        MM_ANONPAGES,
 294        MM_SWAPENTS,
 295        NR_MM_COUNTERS
 296};
 297
 298#if USE_SPLIT_PTLOCKS && defined(CONFIG_MMU)
 299#define SPLIT_RSS_COUNTING
 300/* per-thread cached information, */
 301struct task_rss_stat {
 302        int events;     /* for synchronization threshold */
 303        int count[NR_MM_COUNTERS];
 304};
 305#endif /* USE_SPLIT_PTLOCKS */
 306
 307struct mm_rss_stat {
 308        atomic_long_t count[NR_MM_COUNTERS];
 309};
 310
 311struct mm_struct {
 312        struct vm_area_struct * mmap;           /* list of VMAs */
 313        struct rb_root mm_rb;
 314        struct vm_area_struct * mmap_cache;     /* last find_vma result */
 315#ifdef CONFIG_MMU
 316        unsigned long (*get_unmapped_area) (struct file *filp,
 317                                unsigned long addr, unsigned long len,
 318                                unsigned long pgoff, unsigned long flags);
 319        void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
 320#endif
 321        unsigned long mmap_base;                /* base of mmap area */
 322        unsigned long task_size;                /* size of task vm space */
 323        unsigned long cached_hole_size;         /* if non-zero, the largest hole below free_area_cache */
 324        unsigned long free_area_cache;          /* first hole of size cached_hole_size or larger */
 325        pgd_t * pgd;
 326        atomic_t mm_users;                      /* How many users with user space? */
 327        atomic_t mm_count;                      /* How many references to "struct mm_struct" (users count as 1) */
 328        int map_count;                          /* number of VMAs */
 329
 330        spinlock_t page_table_lock;             /* Protects page tables and some counters */
 331        struct rw_semaphore mmap_sem;
 332
 333        struct list_head mmlist;                /* List of maybe swapped mm's.  These are globally strung
 334                                                 * together off init_mm.mmlist, and are protected
 335                                                 * by mmlist_lock
 336                                                 */
 337
 338
 339        unsigned long hiwater_rss;      /* High-watermark of RSS usage */
 340        unsigned long hiwater_vm;       /* High-water virtual memory usage */
 341
 342        unsigned long total_vm;         /* Total pages mapped */
 343        unsigned long locked_vm;        /* Pages that have PG_mlocked set */
 344        unsigned long pinned_vm;        /* Refcount permanently increased */
 345        unsigned long shared_vm;        /* Shared pages (files) */
 346        unsigned long exec_vm;          /* VM_EXEC & ~VM_WRITE */
 347        unsigned long stack_vm;         /* VM_GROWSUP/DOWN */
 348        unsigned long def_flags;
 349        unsigned long nr_ptes;          /* Page table pages */
 350        unsigned long start_code, end_code, start_data, end_data;
 351        unsigned long start_brk, brk, start_stack;
 352        unsigned long arg_start, arg_end, env_start, env_end;
 353
 354        unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
 355
 356        /*
 357         * Special counters, in some configurations protected by the
 358         * page_table_lock, in other configurations by being atomic.
 359         */
 360        struct mm_rss_stat rss_stat;
 361
 362        struct linux_binfmt *binfmt;
 363
 364        cpumask_var_t cpu_vm_mask_var;
 365
 366        /* Architecture-specific MM context */
 367        mm_context_t context;
 368
 369        unsigned long flags; /* Must use atomic bitops to access the bits */
 370
 371        struct core_state *core_state; /* coredumping support */
 372#ifdef CONFIG_AIO
 373        spinlock_t              ioctx_lock;
 374        struct hlist_head       ioctx_list;
 375#endif
 376#ifdef CONFIG_MM_OWNER
 377        /*
 378         * "owner" points to a task that is regarded as the canonical
 379         * user/owner of this mm. All of the following must be true in
 380         * order for it to be changed:
 381         *
 382         * current == mm->owner
 383         * current->mm != mm
 384         * new_owner->mm == mm
 385         * new_owner->alloc_lock is held
 386         */
 387        struct task_struct __rcu *owner;
 388#endif
 389
 390        /* store ref to file /proc/<pid>/exe symlink points to */
 391        struct file *exe_file;
 392#ifdef CONFIG_MMU_NOTIFIER
 393        struct mmu_notifier_mm *mmu_notifier_mm;
 394#endif
 395#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 396        pgtable_t pmd_huge_pte; /* protected by page_table_lock */
 397#endif
 398#ifdef CONFIG_CPUMASK_OFFSTACK
 399        struct cpumask cpumask_allocation;
 400#endif
 401        struct uprobes_state uprobes_state;
 402};
 403
 404static inline void mm_init_cpumask(struct mm_struct *mm)
 405{
 406#ifdef CONFIG_CPUMASK_OFFSTACK
 407        mm->cpu_vm_mask_var = &mm->cpumask_allocation;
 408#endif
 409}
 410
 411/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
 412static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
 413{
 414        return mm->cpu_vm_mask_var;
 415}
 416
 417#endif /* _LINUX_MM_TYPES_H */
 418
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