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

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