include/linux/mm_types.h

   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 <linux/page-flags-layout.h>
  16 #include <asm/page.h>
  17 #include <asm/mmu.h>
  18
  19 #ifndef AT_VECTOR_SIZE_ARCH
  20 #define AT_VECTOR_SIZE_ARCH 0
  21 #endif
  22 #define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
  23
  24 struct address_space;
  25
  26 #define USE_SPLIT_PTE_PTLOCKS   (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
  27 #define USE_SPLIT_PMD_PTLOCKS   (USE_SPLIT_PTE_PTLOCKS && \
  28                 IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
  29
  30 /*
  31  * Each physical page in the system has a struct page associated with
  32  * it to keep track of whatever it is we are using the page for at the
  33  * moment. Note that we have no way to track which tasks are using
  34  * a page, though if it is a pagecache page, rmap structures can tell us
  35  * who is mapping it.
  36  *
  37  * The objects in struct page are organized in double word blocks in
  38  * order to allows us to use atomic double word operations on portions
  39  * of struct page. That is currently only used by slub but the arrangement
  40  * allows the use of atomic double word operations on the flags/mapping
  41  * and lru list pointers also.
  42  */
  43 struct page {
  44         /* First double word block */
  45         unsigned long flags;            /* Atomic flags, some possibly
  46                                          * updated asynchronously */
  47         union {
  48                 struct address_space *mapping;  /* If low bit clear, points to
  49                                                  * inode address_space, or NULL.
  50                                                  * If page mapped as anonymous
  51                                                  * memory, low bit is set, and
  52                                                  * it points to anon_vma object:
  53                                                  * see PAGE_MAPPING_ANON below.
  54                                                  */
  55                 void *s_mem;                    /* slab first object */
  56         };
  57
  58         /* Second double word */
  59         struct {
  60                 union {
  61                         pgoff_t index;          /* Our offset within mapping. */
  62                         void *freelist;         /* sl[aou]b first free object */
  63                         bool pfmemalloc;        /* If set by the page allocator,
  64                                                  * ALLOC_NO_WATERMARKS was set
  65                                                  * and the low watermark was not
  66                                                  * met implying that the system
  67                                                  * is under some pressure. The
  68                                                  * caller should try ensure
  69                                                  * this page is only used to
  70                                                  * free other pages.
  71                                                  */
  72                 };
  73
  74                 union {
  75 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
  76         defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
  77                         /* Used for cmpxchg_double in slub */
  78                         unsigned long counters;
  79 #else
  80                         /*
  81                          * Keep _count separate from slub cmpxchg_double data.
  82                          * As the rest of the double word is protected by
  83                          * slab_lock but _count is not.
  84                          */
  85                         unsigned counters;
  86 #endif
  87
  88                         struct {
  89
  90                                 union {
  91                                         /*
  92                                          * Count of ptes mapped in
  93                                          * mms, to show when page is
  94                                          * mapped & limit reverse map
  95                                          * searches.
  96                                          *
  97                                          * Used also for tail pages
  98                                          * refcounting instead of
  99                                          * _count. Tail pages cannot
 100                                          * be mapped and keeping the
 101                                          * tail page _count zero at
 102                                          * all times guarantees
 103                                          * get_page_unless_zero() will
 104                                          * never succeed on tail
 105                                          * pages.
 106                                          */
 107                                         atomic_t _mapcount;
 108
 109                                         struct { /* SLUB */
 110                                                 unsigned inuse:16;
 111                                                 unsigned objects:15;
 112                                                 unsigned frozen:1;
 113                                         };
 114                                         int units;      /* SLOB */
 115                                 };
 116                                 atomic_t _count;                /* Usage count, see below. */
 117                         };
 118                         unsigned int active;    /* SLAB */
 119                 };
 120         };
 121
 122         /* Third double word block */
 123         union {
 124                 struct list_head lru;   /* Pageout list, eg. active_list
 125                                          * protected by zone->lru_lock !
 126                                          */
 127                 struct {                /* slub per cpu partial pages */
 128                         struct page *next;      /* Next partial slab */
 129 #ifdef CONFIG_64BIT
 130                         int pages;      /* Nr of partial slabs left */
 131                         int pobjects;   /* Approximate # of objects */
 132 #else
 133                         short int pages;
 134                         short int pobjects;
 135 #endif
 136                 };
 137
 138                 struct list_head list;  /* slobs list of pages */
 139                 struct slab *slab_page; /* slab fields */
 140                 struct rcu_head rcu_head;       /* Used by SLAB
 141                                                  * when destroying via RCU
 142                                                  */
 143 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
 144                 pgtable_t pmd_huge_pte; /* protected by page->ptl */
 145 #endif
 146         };
 147
 148         /* Remainder is not double word aligned */
 149         union {
 150                 unsigned long private;          /* Mapping-private opaque data:
 151                                                  * usually used for buffer_heads
 152                                                  * if PagePrivate set; used for
 153                                                  * swp_entry_t if PageSwapCache;
 154                                                  * indicates order in the buddy
 155                                                  * system if PG_buddy is set.
 156                                                  */
 157 #if USE_SPLIT_PTE_PTLOCKS
 158 #if BLOATED_SPINLOCKS
 159                 spinlock_t *ptl;
 160 #else
 161                 spinlock_t ptl;
 162 #endif
 163 #endif
 164                 struct kmem_cache *slab_cache;  /* SL[AU]B: Pointer to slab */
 165                 struct page *first_page;        /* Compound tail pages */
 166         };
 167
 168         /*
 169          * On machines where all RAM is mapped into kernel address space,
 170          * we can simply calculate the virtual address. On machines with
 171          * highmem some memory is mapped into kernel virtual memory
 172          * dynamically, so we need a place to store that address.
 173          * Note that this field could be 16 bits on x86 ... ;)
 174          *
 175          * Architectures with slow multiplication can define
 176          * WANT_PAGE_VIRTUAL in asm/page.h
 177          */
 178 #if defined(WANT_PAGE_VIRTUAL)
 179         void *virtual;                  /* Kernel virtual address (NULL if
 180                                            not kmapped, ie. highmem) */
 181 #endif /* WANT_PAGE_VIRTUAL */
 182 #ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
 183         unsigned long debug_flags;      /* Use atomic bitops on this */
 184 #endif
 185
 186 #ifdef CONFIG_KMEMCHECK
 187         /*
 188          * kmemcheck wants to track the status of each byte in a page; this
 189          * is a pointer to such a status block. NULL if not tracked.
 190          */
 191         void *shadow;
 192 #endif
 193
 194 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
 195         int _last_cpupid;
 196 #endif
 197 }
 198 /*
 199  * The struct page can be forced to be double word aligned so that atomic ops
 200  * on double words work. The SLUB allocator can make use of such a feature.
 201  */
 202 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
 203         __aligned(2 * sizeof(unsigned long))
 204 #endif
 205 ;
 206
 207 struct page_frag {
 208         struct page *page;
 209 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
 210         __u32 offset;
 211         __u32 size;
 212 #else
 213         __u16 offset;
 214         __u16 size;
 215 #endif
 216 };
 217
 218 typedef unsigned long __nocast vm_flags_t;
 219
 220 /*
 221  * A region containing a mapping of a non-memory backed file under NOMMU
 222  * conditions.  These are held in a global tree and are pinned by the VMAs that
 223  * map parts of them.
 224  */
 225 struct vm_region {
 226         struct rb_node  vm_rb;          /* link in global region tree */
 227         vm_flags_t      vm_flags;       /* VMA vm_flags */
 228         unsigned long   vm_start;       /* start address of region */
 229         unsigned long   vm_end;         /* region initialised to here */
 230         unsigned long   vm_top;         /* region allocated to here */
 231         unsigned long   vm_pgoff;       /* the offset in vm_file corresponding to vm_start */
 232         struct file     *vm_file;       /* the backing file or NULL */
 233
 234         int             vm_usage;       /* region usage count (access under nommu_region_sem) */
 235         bool            vm_icache_flushed : 1; /* true if the icache has been flushed for
 236                                                 * this region */
 237 };
 238
 239 /*
 240  * This struct defines a memory VMM memory area. There is one of these
 241  * per VM-area/task.  A VM area is any part of the process virtual memory
 242  * space that has a special rule for the page-fault handlers (ie a shared
 243  * library, the executable area etc).
 244  */
 245 struct vm_area_struct {
 246         /* The first cache line has the info for VMA tree walking. */
 247
 248         unsigned long vm_start;         /* Our start address within vm_mm. */
 249         unsigned long vm_end;           /* The first byte after our end address
 250                                            within vm_mm. */
 251
 252         /* linked list of VM areas per task, sorted by address */
 253         struct vm_area_struct *vm_next, *vm_prev;
 254
 255         struct rb_node vm_rb;
 256
 257         /*
 258          * Largest free memory gap in bytes to the left of this VMA.
 259          * Either between this VMA and vma->vm_prev, or between one of the
 260          * VMAs below us in the VMA rbtree and its ->vm_prev. This helps
 261          * get_unmapped_area find a free area of the right size.
 262          */
 263         unsigned long rb_subtree_gap;
 264
 265         /* Second cache line starts here. */
 266
 267         struct mm_struct *vm_mm;        /* The address space we belong to. */
 268         pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
 269         unsigned long vm_flags;         /* Flags, see mm.h. */
 270
 271         /*
 272          * For areas with an address space and backing store,
 273          * linkage into the address_space->i_mmap interval tree, or
 274          * linkage of vma in the address_space->i_mmap_nonlinear list.
 275          */
 276         union {
 277                 struct {
 278                         struct rb_node rb;
 279                         unsigned long rb_subtree_last;
 280                 } linear;
 281                 struct list_head nonlinear;
 282         } shared;
 283
 284         /*
 285          * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
 286          * list, after a COW of one of the file pages.  A MAP_SHARED vma
 287          * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
 288          * or brk vma (with NULL file) can only be in an anon_vma list.
 289          */
 290         struct list_head anon_vma_chain; /* Serialized by mmap_sem &
 291                                           * page_table_lock */
 292         struct anon_vma *anon_vma;      /* Serialized by page_table_lock */
 293
 294         /* Function pointers to deal with this struct. */
 295         const struct vm_operations_struct *vm_ops;
 296
 297         /* Information about our backing store: */
 298         unsigned long vm_pgoff;         /* Offset (within vm_file) in PAGE_SIZE
 299                                            units, *not* PAGE_CACHE_SIZE */
 300         struct file * vm_file;          /* File we map to (can be NULL). */
 301         void * vm_private_data;         /* was vm_pte (shared mem) */
 302
 303 #ifndef CONFIG_MMU
 304         struct vm_region *vm_region;    /* NOMMU mapping region */
 305 #endif
 306 #ifdef CONFIG_NUMA
 307         struct mempolicy *vm_policy;    /* NUMA policy for the VMA */
 308 #endif
 309 };
 310
 311 struct core_thread {
 312         struct task_struct *task;
 313         struct core_thread *next;
 314 };
 315
 316 struct core_state {
 317         atomic_t nr_threads;
 318         struct core_thread dumper;
 319         struct completion startup;
 320 };
 321
 322 enum {
 323         MM_FILEPAGES,
 324         MM_ANONPAGES,
 325         MM_SWAPENTS,
 326         NR_MM_COUNTERS
 327 };
 328
 329 #if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
 330 #define SPLIT_RSS_COUNTING
 331 /* per-thread cached information, */
 332 struct task_rss_stat {
 333         int events;     /* for synchronization threshold */
 334         int count[NR_MM_COUNTERS];
 335 };
 336 #endif /* USE_SPLIT_PTE_PTLOCKS */
 337
 338 struct mm_rss_stat {
 339         atomic_long_t count[NR_MM_COUNTERS];
 340 };
 341
 342 struct kioctx_table;
 343 struct mm_struct {
 344         struct vm_area_struct * mmap;           /* list of VMAs */
 345         struct rb_root mm_rb;
 346         struct vm_area_struct * mmap_cache;     /* last find_vma result */
 347 #ifdef CONFIG_MMU
 348         unsigned long (*get_unmapped_area) (struct file *filp,
 349                                 unsigned long addr, unsigned long len,
 350                                 unsigned long pgoff, unsigned long flags);
 351 #endif
 352         unsigned long mmap_base;                /* base of mmap area */
 353         unsigned long mmap_legacy_base;         /* base of mmap area in bottom-up allocations */
 354         unsigned long task_size;                /* size of task vm space */
 355         unsigned long highest_vm_end;           /* highest vma end address */
 356         pgd_t * pgd;
 357         atomic_t mm_users;                      /* How many users with user space? */
 358         atomic_t mm_count;                      /* How many references to "struct mm_struct" (users count as 1) */
 359         atomic_long_t nr_ptes;                  /* Page table pages */
 360         int map_count;                          /* number of VMAs */
 361
 362         spinlock_t page_table_lock;             /* Protects page tables and some counters */
 363         struct rw_semaphore mmap_sem;
 364
 365         struct list_head mmlist;                /* List of maybe swapped mm's.  These are globally strung
 366                                                  * together off init_mm.mmlist, and are protected
 367                                                  * by mmlist_lock
 368                                                  */
 369
 370
 371         unsigned long hiwater_rss;      /* High-watermark of RSS usage */
 372         unsigned long hiwater_vm;       /* High-water virtual memory usage */
 373
 374         unsigned long total_vm;         /* Total pages mapped */
 375         unsigned long locked_vm;        /* Pages that have PG_mlocked set */
 376         unsigned long pinned_vm;        /* Refcount permanently increased */
 377         unsigned long shared_vm;        /* Shared pages (files) */
 378         unsigned long exec_vm;          /* VM_EXEC & ~VM_WRITE */
 379         unsigned long stack_vm;         /* VM_GROWSUP/DOWN */
 380         unsigned long def_flags;
 381         unsigned long start_code, end_code, start_data, end_data;
 382         unsigned long start_brk, brk, start_stack;
 383         unsigned long arg_start, arg_end, env_start, env_end;
 384
 385         unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
 386
 387         /*
 388          * Special counters, in some configurations protected by the
 389          * page_table_lock, in other configurations by being atomic.
 390          */
 391         struct mm_rss_stat rss_stat;
 392
 393         struct linux_binfmt *binfmt;
 394
 395         cpumask_var_t cpu_vm_mask_var;
 396
 397         /* Architecture-specific MM context */
 398         mm_context_t context;
 399
 400         unsigned long flags; /* Must use atomic bitops to access the bits */
 401
 402         struct core_state *core_state; /* coredumping support */
 403 #ifdef CONFIG_AIO
 404         spinlock_t                      ioctx_lock;
 405         struct kioctx_table __rcu       *ioctx_table;
 406 #endif
 407 #ifdef CONFIG_MM_OWNER
 408         /*
 409          * "owner" points to a task that is regarded as the canonical
 410          * user/owner of this mm. All of the following must be true in
 411          * order for it to be changed:
 412          *
 413          * current == mm->owner
 414          * current->mm != mm
 415          * new_owner->mm == mm
 416          * new_owner->alloc_lock is held
 417          */
 418         struct task_struct __rcu *owner;
 419 #endif
 420
 421         /* store ref to file /proc/<pid>/exe symlink points to */
 422         struct file *exe_file;
 423 #ifdef CONFIG_MMU_NOTIFIER
 424         struct mmu_notifier_mm *mmu_notifier_mm;
 425 #endif
 426 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
 427         pgtable_t pmd_huge_pte; /* protected by page_table_lock */
 428 #endif
 429 #ifdef CONFIG_CPUMASK_OFFSTACK
 430         struct cpumask cpumask_allocation;
 431 #endif
 432 #ifdef CONFIG_NUMA_BALANCING
 433         /*
 434          * numa_next_scan is the next time that the PTEs will be marked
 435          * pte_numa. NUMA hinting faults will gather statistics and migrate
 436          * pages to new nodes if necessary.
 437          */
 438         unsigned long numa_next_scan;
 439
 440         /* Restart point for scanning and setting pte_numa */
 441         unsigned long numa_scan_offset;
 442
 443         /* numa_scan_seq prevents two threads setting pte_numa */
 444         int numa_scan_seq;
 445 #endif
 446         struct uprobes_state uprobes_state;
 447 };
 448
 449 static inline void mm_init_cpumask(struct mm_struct *mm)
 450 {
 451 #ifdef CONFIG_CPUMASK_OFFSTACK
 452         mm->cpu_vm_mask_var = &mm->cpumask_allocation;
 453 #endif
 454 }
 455
 456 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
 457 static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
 458 {
 459         return mm->cpu_vm_mask_var;
 460 }
 461
 462 #endif /* _LINUX_MM_TYPES_H */