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

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