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Linux/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/uprobes.h>
 14 #include <linux/page-flags-layout.h>
 15 #include <linux/workqueue.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 struct mem_cgroup;
 26 
 27 #define USE_SPLIT_PTE_PTLOCKS   (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
 28 #define USE_SPLIT_PMD_PTLOCKS   (USE_SPLIT_PTE_PTLOCKS && \
 29                 IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
 30 #define ALLOC_SPLIT_PTLOCKS     (SPINLOCK_SIZE > BITS_PER_LONG/8)
 31 
 32 /*
 33  * Each physical page in the system has a struct page associated with
 34  * it to keep track of whatever it is we are using the page for at the
 35  * moment. Note that we have no way to track which tasks are using
 36  * a page, though if it is a pagecache page, rmap structures can tell us
 37  * who is mapping it.
 38  *
 39  * The objects in struct page are organized in double word blocks in
 40  * order to allows us to use atomic double word operations on portions
 41  * of struct page. That is currently only used by slub but the arrangement
 42  * allows the use of atomic double word operations on the flags/mapping
 43  * and lru list pointers also.
 44  */
 45 struct page {
 46         /* First double word block */
 47         unsigned long flags;            /* Atomic flags, some possibly
 48                                          * updated asynchronously */
 49         union {
 50                 struct address_space *mapping;  /* If low bit clear, points to
 51                                                  * inode address_space, or NULL.
 52                                                  * If page mapped as anonymous
 53                                                  * memory, low bit is set, and
 54                                                  * it points to anon_vma object:
 55                                                  * see PAGE_MAPPING_ANON below.
 56                                                  */
 57                 void *s_mem;                    /* slab first object */
 58                 atomic_t compound_mapcount;     /* first tail page */
 59                 /* page_deferred_list().next     -- second tail page */
 60         };
 61 
 62         /* Second double word */
 63         union {
 64                 pgoff_t index;          /* Our offset within mapping. */
 65                 void *freelist;         /* sl[aou]b first free object */
 66                 /* page_deferred_list().prev    -- second tail page */
 67         };
 68 
 69         union {
 70 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
 71         defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
 72                 /* Used for cmpxchg_double in slub */
 73                 unsigned long counters;
 74 #else
 75                 /*
 76                  * Keep _refcount separate from slub cmpxchg_double data.
 77                  * As the rest of the double word is protected by slab_lock
 78                  * but _refcount is not.
 79                  */
 80                 unsigned counters;
 81 #endif
 82                 struct {
 83 
 84                         union {
 85                                 /*
 86                                  * Count of ptes mapped in mms, to show when
 87                                  * page is mapped & limit reverse map searches.
 88                                  *
 89                                  * Extra information about page type may be
 90                                  * stored here for pages that are never mapped,
 91                                  * in which case the value MUST BE <= -2.
 92                                  * See page-flags.h for more details.
 93                                  */
 94                                 atomic_t _mapcount;
 95 
 96                                 unsigned int active;            /* SLAB */
 97                                 struct {                        /* SLUB */
 98                                         unsigned inuse:16;
 99                                         unsigned objects:15;
100                                         unsigned frozen:1;
101                                 };
102                                 int units;                      /* SLOB */
103                         };
104                         /*
105                          * Usage count, *USE WRAPPER FUNCTION* when manual
106                          * accounting. See page_ref.h
107                          */
108                         atomic_t _refcount;
109                 };
110         };
111 
112         /*
113          * Third double word block
114          *
115          * WARNING: bit 0 of the first word encode PageTail(). That means
116          * the rest users of the storage space MUST NOT use the bit to
117          * avoid collision and false-positive PageTail().
118          */
119         union {
120                 struct list_head lru;   /* Pageout list, eg. active_list
121                                          * protected by zone_lru_lock !
122                                          * Can be used as a generic list
123                                          * by the page owner.
124                                          */
125                 struct dev_pagemap *pgmap; /* ZONE_DEVICE pages are never on an
126                                             * lru or handled by a slab
127                                             * allocator, this points to the
128                                             * hosting device page map.
129                                             */
130                 struct {                /* slub per cpu partial pages */
131                         struct page *next;      /* Next partial slab */
132 #ifdef CONFIG_64BIT
133                         int pages;      /* Nr of partial slabs left */
134                         int pobjects;   /* Approximate # of objects */
135 #else
136                         short int pages;
137                         short int pobjects;
138 #endif
139                 };
140 
141                 struct rcu_head rcu_head;       /* Used by SLAB
142                                                  * when destroying via RCU
143                                                  */
144                 /* Tail pages of compound page */
145                 struct {
146                         unsigned long compound_head; /* If bit zero is set */
147 
148                         /* First tail page only */
149 #ifdef CONFIG_64BIT
150                         /*
151                          * On 64 bit system we have enough space in struct page
152                          * to encode compound_dtor and compound_order with
153                          * unsigned int. It can help compiler generate better or
154                          * smaller code on some archtectures.
155                          */
156                         unsigned int compound_dtor;
157                         unsigned int compound_order;
158 #else
159                         unsigned short int compound_dtor;
160                         unsigned short int compound_order;
161 #endif
162                 };
163 
164 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
165                 struct {
166                         unsigned long __pad;    /* do not overlay pmd_huge_pte
167                                                  * with compound_head to avoid
168                                                  * possible bit 0 collision.
169                                                  */
170                         pgtable_t pmd_huge_pte; /* protected by page->ptl */
171                 };
172 #endif
173         };
174 
175         /* Remainder is not double word aligned */
176         union {
177                 unsigned long private;          /* Mapping-private opaque data:
178                                                  * usually used for buffer_heads
179                                                  * if PagePrivate set; used for
180                                                  * swp_entry_t if PageSwapCache;
181                                                  * indicates order in the buddy
182                                                  * system if PG_buddy is set.
183                                                  */
184 #if USE_SPLIT_PTE_PTLOCKS
185 #if ALLOC_SPLIT_PTLOCKS
186                 spinlock_t *ptl;
187 #else
188                 spinlock_t ptl;
189 #endif
190 #endif
191                 struct kmem_cache *slab_cache;  /* SL[AU]B: Pointer to slab */
192         };
193 
194 #ifdef CONFIG_MEMCG
195         struct mem_cgroup *mem_cgroup;
196 #endif
197 
198         /*
199          * On machines where all RAM is mapped into kernel address space,
200          * we can simply calculate the virtual address. On machines with
201          * highmem some memory is mapped into kernel virtual memory
202          * dynamically, so we need a place to store that address.
203          * Note that this field could be 16 bits on x86 ... ;)
204          *
205          * Architectures with slow multiplication can define
206          * WANT_PAGE_VIRTUAL in asm/page.h
207          */
208 #if defined(WANT_PAGE_VIRTUAL)
209         void *virtual;                  /* Kernel virtual address (NULL if
210                                            not kmapped, ie. highmem) */
211 #endif /* WANT_PAGE_VIRTUAL */
212 
213 #ifdef CONFIG_KMEMCHECK
214         /*
215          * kmemcheck wants to track the status of each byte in a page; this
216          * is a pointer to such a status block. NULL if not tracked.
217          */
218         void *shadow;
219 #endif
220 
221 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
222         int _last_cpupid;
223 #endif
224 }
225 /*
226  * The struct page can be forced to be double word aligned so that atomic ops
227  * on double words work. The SLUB allocator can make use of such a feature.
228  */
229 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
230         __aligned(2 * sizeof(unsigned long))
231 #endif
232 ;
233 
234 struct page_frag {
235         struct page *page;
236 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
237         __u32 offset;
238         __u32 size;
239 #else
240         __u16 offset;
241         __u16 size;
242 #endif
243 };
244 
245 #define PAGE_FRAG_CACHE_MAX_SIZE        __ALIGN_MASK(32768, ~PAGE_MASK)
246 #define PAGE_FRAG_CACHE_MAX_ORDER       get_order(PAGE_FRAG_CACHE_MAX_SIZE)
247 
248 struct page_frag_cache {
249         void * va;
250 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
251         __u16 offset;
252         __u16 size;
253 #else
254         __u32 offset;
255 #endif
256         /* we maintain a pagecount bias, so that we dont dirty cache line
257          * containing page->_refcount every time we allocate a fragment.
258          */
259         unsigned int            pagecnt_bias;
260         bool pfmemalloc;
261 };
262 
263 typedef unsigned long vm_flags_t;
264 
265 /*
266  * A region containing a mapping of a non-memory backed file under NOMMU
267  * conditions.  These are held in a global tree and are pinned by the VMAs that
268  * map parts of them.
269  */
270 struct vm_region {
271         struct rb_node  vm_rb;          /* link in global region tree */
272         vm_flags_t      vm_flags;       /* VMA vm_flags */
273         unsigned long   vm_start;       /* start address of region */
274         unsigned long   vm_end;         /* region initialised to here */
275         unsigned long   vm_top;         /* region allocated to here */
276         unsigned long   vm_pgoff;       /* the offset in vm_file corresponding to vm_start */
277         struct file     *vm_file;       /* the backing file or NULL */
278 
279         int             vm_usage;       /* region usage count (access under nommu_region_sem) */
280         bool            vm_icache_flushed : 1; /* true if the icache has been flushed for
281                                                 * this region */
282 };
283 
284 #ifdef CONFIG_USERFAULTFD
285 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, })
286 struct vm_userfaultfd_ctx {
287         struct userfaultfd_ctx *ctx;
288 };
289 #else /* CONFIG_USERFAULTFD */
290 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
291 struct vm_userfaultfd_ctx {};
292 #endif /* CONFIG_USERFAULTFD */
293 
294 /*
295  * This struct defines a memory VMM memory area. There is one of these
296  * per VM-area/task.  A VM area is any part of the process virtual memory
297  * space that has a special rule for the page-fault handlers (ie a shared
298  * library, the executable area etc).
299  */
300 struct vm_area_struct {
301         /* The first cache line has the info for VMA tree walking. */
302 
303         unsigned long vm_start;         /* Our start address within vm_mm. */
304         unsigned long vm_end;           /* The first byte after our end address
305                                            within vm_mm. */
306 
307         /* linked list of VM areas per task, sorted by address */
308         struct vm_area_struct *vm_next, *vm_prev;
309 
310         struct rb_node vm_rb;
311 
312         /*
313          * Largest free memory gap in bytes to the left of this VMA.
314          * Either between this VMA and vma->vm_prev, or between one of the
315          * VMAs below us in the VMA rbtree and its ->vm_prev. This helps
316          * get_unmapped_area find a free area of the right size.
317          */
318         unsigned long rb_subtree_gap;
319 
320         /* Second cache line starts here. */
321 
322         struct mm_struct *vm_mm;        /* The address space we belong to. */
323         pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
324         unsigned long vm_flags;         /* Flags, see mm.h. */
325 
326         /*
327          * For areas with an address space and backing store,
328          * linkage into the address_space->i_mmap interval tree.
329          */
330         struct {
331                 struct rb_node rb;
332                 unsigned long rb_subtree_last;
333         } shared;
334 
335         /*
336          * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
337          * list, after a COW of one of the file pages.  A MAP_SHARED vma
338          * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
339          * or brk vma (with NULL file) can only be in an anon_vma list.
340          */
341         struct list_head anon_vma_chain; /* Serialized by mmap_sem &
342                                           * page_table_lock */
343         struct anon_vma *anon_vma;      /* Serialized by page_table_lock */
344 
345         /* Function pointers to deal with this struct. */
346         const struct vm_operations_struct *vm_ops;
347 
348         /* Information about our backing store: */
349         unsigned long vm_pgoff;         /* Offset (within vm_file) in PAGE_SIZE
350                                            units */
351         struct file * vm_file;          /* File we map to (can be NULL). */
352         void * vm_private_data;         /* was vm_pte (shared mem) */
353 
354 #ifndef CONFIG_MMU
355         struct vm_region *vm_region;    /* NOMMU mapping region */
356 #endif
357 #ifdef CONFIG_NUMA
358         struct mempolicy *vm_policy;    /* NUMA policy for the VMA */
359 #endif
360         struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
361 };
362 
363 struct core_thread {
364         struct task_struct *task;
365         struct core_thread *next;
366 };
367 
368 struct core_state {
369         atomic_t nr_threads;
370         struct core_thread dumper;
371         struct completion startup;
372 };
373 
374 enum {
375         MM_FILEPAGES,   /* Resident file mapping pages */
376         MM_ANONPAGES,   /* Resident anonymous pages */
377         MM_SWAPENTS,    /* Anonymous swap entries */
378         MM_SHMEMPAGES,  /* Resident shared memory pages */
379         NR_MM_COUNTERS
380 };
381 
382 #if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
383 #define SPLIT_RSS_COUNTING
384 /* per-thread cached information, */
385 struct task_rss_stat {
386         int events;     /* for synchronization threshold */
387         int count[NR_MM_COUNTERS];
388 };
389 #endif /* USE_SPLIT_PTE_PTLOCKS */
390 
391 struct mm_rss_stat {
392         atomic_long_t count[NR_MM_COUNTERS];
393 };
394 
395 struct kioctx_table;
396 struct mm_struct {
397         struct vm_area_struct *mmap;            /* list of VMAs */
398         struct rb_root mm_rb;
399         u32 vmacache_seqnum;                   /* per-thread vmacache */
400 #ifdef CONFIG_MMU
401         unsigned long (*get_unmapped_area) (struct file *filp,
402                                 unsigned long addr, unsigned long len,
403                                 unsigned long pgoff, unsigned long flags);
404 #endif
405         unsigned long mmap_base;                /* base of mmap area */
406         unsigned long mmap_legacy_base;         /* base of mmap area in bottom-up allocations */
407         unsigned long task_size;                /* size of task vm space */
408         unsigned long highest_vm_end;           /* highest vma end address */
409         pgd_t * pgd;
410         atomic_t mm_users;                      /* How many users with user space? */
411         atomic_t mm_count;                      /* How many references to "struct mm_struct" (users count as 1) */
412         atomic_long_t nr_ptes;                  /* PTE page table pages */
413 #if CONFIG_PGTABLE_LEVELS > 2
414         atomic_long_t nr_pmds;                  /* PMD page table pages */
415 #endif
416         int map_count;                          /* number of VMAs */
417 
418         spinlock_t page_table_lock;             /* Protects page tables and some counters */
419         struct rw_semaphore mmap_sem;
420 
421         struct list_head mmlist;                /* List of maybe swapped mm's.  These are globally strung
422                                                  * together off init_mm.mmlist, and are protected
423                                                  * by mmlist_lock
424                                                  */
425 
426 
427         unsigned long hiwater_rss;      /* High-watermark of RSS usage */
428         unsigned long hiwater_vm;       /* High-water virtual memory usage */
429 
430         unsigned long total_vm;         /* Total pages mapped */
431         unsigned long locked_vm;        /* Pages that have PG_mlocked set */
432         unsigned long pinned_vm;        /* Refcount permanently increased */
433         unsigned long data_vm;          /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
434         unsigned long exec_vm;          /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
435         unsigned long stack_vm;         /* VM_STACK */
436         unsigned long def_flags;
437         unsigned long start_code, end_code, start_data, end_data;
438         unsigned long start_brk, brk, start_stack;
439         unsigned long arg_start, arg_end, env_start, env_end;
440 
441         unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
442 
443         /*
444          * Special counters, in some configurations protected by the
445          * page_table_lock, in other configurations by being atomic.
446          */
447         struct mm_rss_stat rss_stat;
448 
449         struct linux_binfmt *binfmt;
450 
451         cpumask_var_t cpu_vm_mask_var;
452 
453         /* Architecture-specific MM context */
454         mm_context_t context;
455 
456         unsigned long flags; /* Must use atomic bitops to access the bits */
457 
458         struct core_state *core_state; /* coredumping support */
459 #ifdef CONFIG_AIO
460         spinlock_t                      ioctx_lock;
461         struct kioctx_table __rcu       *ioctx_table;
462 #endif
463 #ifdef CONFIG_MEMCG
464         /*
465          * "owner" points to a task that is regarded as the canonical
466          * user/owner of this mm. All of the following must be true in
467          * order for it to be changed:
468          *
469          * current == mm->owner
470          * current->mm != mm
471          * new_owner->mm == mm
472          * new_owner->alloc_lock is held
473          */
474         struct task_struct __rcu *owner;
475 #endif
476 
477         /* store ref to file /proc/<pid>/exe symlink points to */
478         struct file __rcu *exe_file;
479 #ifdef CONFIG_MMU_NOTIFIER
480         struct mmu_notifier_mm *mmu_notifier_mm;
481 #endif
482 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
483         pgtable_t pmd_huge_pte; /* protected by page_table_lock */
484 #endif
485 #ifdef CONFIG_CPUMASK_OFFSTACK
486         struct cpumask cpumask_allocation;
487 #endif
488 #ifdef CONFIG_NUMA_BALANCING
489         /*
490          * numa_next_scan is the next time that the PTEs will be marked
491          * pte_numa. NUMA hinting faults will gather statistics and migrate
492          * pages to new nodes if necessary.
493          */
494         unsigned long numa_next_scan;
495 
496         /* Restart point for scanning and setting pte_numa */
497         unsigned long numa_scan_offset;
498 
499         /* numa_scan_seq prevents two threads setting pte_numa */
500         int numa_scan_seq;
501 #endif
502 #if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
503         /*
504          * An operation with batched TLB flushing is going on. Anything that
505          * can move process memory needs to flush the TLB when moving a
506          * PROT_NONE or PROT_NUMA mapped page.
507          */
508         bool tlb_flush_pending;
509 #endif
510         struct uprobes_state uprobes_state;
511 #ifdef CONFIG_X86_INTEL_MPX
512         /* address of the bounds directory */
513         void __user *bd_addr;
514 #endif
515 #ifdef CONFIG_HUGETLB_PAGE
516         atomic_long_t hugetlb_usage;
517 #endif
518 #ifdef CONFIG_MMU
519         struct work_struct async_put_work;
520 #endif
521 };
522 
523 static inline void mm_init_cpumask(struct mm_struct *mm)
524 {
525 #ifdef CONFIG_CPUMASK_OFFSTACK
526         mm->cpu_vm_mask_var = &mm->cpumask_allocation;
527 #endif
528         cpumask_clear(mm->cpu_vm_mask_var);
529 }
530 
531 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
532 static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
533 {
534         return mm->cpu_vm_mask_var;
535 }
536 
537 #if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
538 /*
539  * Memory barriers to keep this state in sync are graciously provided by
540  * the page table locks, outside of which no page table modifications happen.
541  * The barriers below prevent the compiler from re-ordering the instructions
542  * around the memory barriers that are already present in the code.
543  */
544 static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
545 {
546         barrier();
547         return mm->tlb_flush_pending;
548 }
549 static inline void set_tlb_flush_pending(struct mm_struct *mm)
550 {
551         mm->tlb_flush_pending = true;
552 
553         /*
554          * Guarantee that the tlb_flush_pending store does not leak into the
555          * critical section updating the page tables
556          */
557         smp_mb__before_spinlock();
558 }
559 /* Clearing is done after a TLB flush, which also provides a barrier. */
560 static inline void clear_tlb_flush_pending(struct mm_struct *mm)
561 {
562         barrier();
563         mm->tlb_flush_pending = false;
564 }
565 #else
566 static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
567 {
568         return false;
569 }
570 static inline void set_tlb_flush_pending(struct mm_struct *mm)
571 {
572 }
573 static inline void clear_tlb_flush_pending(struct mm_struct *mm)
574 {
575 }
576 #endif
577 
578 struct vm_fault;
579 
580 struct vm_special_mapping {
581         const char *name;       /* The name, e.g. "[vdso]". */
582 
583         /*
584          * If .fault is not provided, this points to a
585          * NULL-terminated array of pages that back the special mapping.
586          *
587          * This must not be NULL unless .fault is provided.
588          */
589         struct page **pages;
590 
591         /*
592          * If non-NULL, then this is called to resolve page faults
593          * on the special mapping.  If used, .pages is not checked.
594          */
595         int (*fault)(const struct vm_special_mapping *sm,
596                      struct vm_area_struct *vma,
597                      struct vm_fault *vmf);
598 
599         int (*mremap)(const struct vm_special_mapping *sm,
600                      struct vm_area_struct *new_vma);
601 };
602 
603 enum tlb_flush_reason {
604         TLB_FLUSH_ON_TASK_SWITCH,
605         TLB_REMOTE_SHOOTDOWN,
606         TLB_LOCAL_SHOOTDOWN,
607         TLB_LOCAL_MM_SHOOTDOWN,
608         TLB_REMOTE_SEND_IPI,
609         NR_TLB_FLUSH_REASONS,
610 };
611 
612  /*
613   * A swap entry has to fit into a "unsigned long", as the entry is hidden
614   * in the "index" field of the swapper address space.
615   */
616 typedef struct {
617         unsigned long val;
618 } swp_entry_t;
619 
620 #endif /* _LINUX_MM_TYPES_H */
621 

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