1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MM_TYPES_H
3 #define _LINUX_MM_TYPES_H
4
5 #include <linux/mm_types_task.h>
6
7 #include <linux/auxvec.h>
8 #include <linux/kref.h>
9 #include <linux/list.h>
10 #include <linux/spinlock.h>
11 #include <linux/rbtree.h>
12 #include <linux/maple_tree.h>
13 #include <linux/rwsem.h>
14 #include <linux/completion.h>
15 #include <linux/cpumask.h>
16 #include <linux/uprobes.h>
17 #include <linux/rcupdate.h>
18 #include <linux/page-flags-layout.h>
19 #include <linux/workqueue.h>
20 #include <linux/seqlock.h>
21 #include <linux/percpu_counter.h>
22
23 #include <asm/mmu.h>
24
25 #ifndef AT_VECTOR_SIZE_ARCH
26 #define AT_VECTOR_SIZE_ARCH 0
27 #endif
28 #define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
29
30 #define INIT_PASID 0
31
32 struct address_space;
33 struct mem_cgroup;
34
35 /*
36 * Each physical page in the system has a struct page associated with
37 * it to keep track of whatever it is we are using the page for at the
38 * moment. Note that we have no way to track which tasks are using
39 * a page, though if it is a pagecache page, rmap structures can tell us
40 * who is mapping it.
41 *
42 * If you allocate the page using alloc_pages(), you can use some of the
43 * space in struct page for your own purposes. The five words in the main
44 * union are available, except for bit 0 of the first word which must be
45 * kept clear. Many users use this word to store a pointer to an object
46 * which is guaranteed to be aligned. If you use the same storage as
47 * page->mapping, you must restore it to NULL before freeing the page.
48 *
49 * If your page will not be mapped to userspace, you can also use the four
50 * bytes in the mapcount union, but you must call page_mapcount_reset()
51 * before freeing it.
52 *
53 * If you want to use the refcount field, it must be used in such a way
54 * that other CPUs temporarily incrementing and then decrementing the
55 * refcount does not cause problems. On receiving the page from
56 * alloc_pages(), the refcount will be positive.
57 *
58 * If you allocate pages of order > 0, you can use some of the fields
59 * in each subpage, but you may need to restore some of their values
60 * afterwards.
61 *
62 * SLUB uses cmpxchg_double() to atomically update its freelist and counters.
63 * That requires that freelist & counters in struct slab be adjacent and
64 * double-word aligned. Because struct slab currently just reinterprets the
65 * bits of struct page, we align all struct pages to double-word boundaries,
66 * and ensure that 'freelist' is aligned within struct slab.
67 */
68 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
69 #define _struct_page_alignment __aligned(2 * sizeof(unsigned long))
70 #else
71 #define _struct_page_alignment __aligned(sizeof(unsigned long))
72 #endif
73
74 struct page {
75 unsigned long flags; /* Atomic flags, some possibly
76 * updated asynchronously */
77 /*
78 * Five words (20/40 bytes) are available in this union.
79 * WARNING: bit 0 of the first word is used for PageTail(). That
80 * means the other users of this union MUST NOT use the bit to
81 * avoid collision and false-positive PageTail().
82 */
83 union {
84 struct { /* Page cache and anonymous pages */
85 /**
86 * @lru: Pageout list, eg. active_list protected by
87 * lruvec->lru_lock. Sometimes used as a generic list
88 * by the page owner.
89 */
90 union {
91 struct list_head lru;
92
93 /* Or, for the Unevictable "LRU list" slot */
94 struct {
95 /* Always even, to negate PageTail */
96 void *__filler;
97 /* Count page's or folio's mlocks */
98 unsigned int mlock_count;
99 };
100
101 /* Or, free page */
102 struct list_head buddy_list;
103 struct list_head pcp_list;
104 };
105 /* See page-flags.h for PAGE_MAPPING_FLAGS */
106 struct address_space *mapping;
107 union {
108 pgoff_t index; /* Our offset within mapping. */
109 unsigned long share; /* share count for fsdax */
110 };
111 /**
112 * @private: Mapping-private opaque data.
113 * Usually used for buffer_heads if PagePrivate.
114 * Used for swp_entry_t if PageSwapCache.
115 * Indicates order in the buddy system if PageBuddy.
116 */
117 unsigned long private;
118 };
119 struct { /* page_pool used by netstack */
120 /**
121 * @pp_magic: magic value to avoid recycling non
122 * page_pool allocated pages.
123 */
124 unsigned long pp_magic;
125 struct page_pool *pp;
126 unsigned long _pp_mapping_pad;
127 unsigned long dma_addr;
128 atomic_long_t pp_ref_count;
129 };
130 struct { /* Tail pages of compound page */
131 unsigned long compound_head; /* Bit zero is set */
132 };
133 struct { /* ZONE_DEVICE pages */
134 /** @pgmap: Points to the hosting device page map. */
135 struct dev_pagemap *pgmap;
136 void *zone_device_data;
137 /*
138 * ZONE_DEVICE private pages are counted as being
139 * mapped so the next 3 words hold the mapping, index,
140 * and private fields from the source anonymous or
141 * page cache page while the page is migrated to device
142 * private memory.
143 * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also
144 * use the mapping, index, and private fields when
145 * pmem backed DAX files are mapped.
146 */
147 };
148
149 /** @rcu_head: You can use this to free a page by RCU. */
150 struct rcu_head rcu_head;
151 };
152
153 union { /* This union is 4 bytes in size. */
154 /*
155 * If the page can be mapped to userspace, encodes the number
156 * of times this page is referenced by a page table.
157 */
158 atomic_t _mapcount;
159
160 /*
161 * If the page is neither PageSlab nor mappable to userspace,
162 * the value stored here may help determine what this page
163 * is used for. See page-flags.h for a list of page types
164 * which are currently stored here.
165 */
166 unsigned int page_type;
167 };
168
169 /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
170 atomic_t _refcount;
171
172 #ifdef CONFIG_MEMCG
173 unsigned long memcg_data;
174 #endif
175
176 /*
177 * On machines where all RAM is mapped into kernel address space,
178 * we can simply calculate the virtual address. On machines with
179 * highmem some memory is mapped into kernel virtual memory
180 * dynamically, so we need a place to store that address.
181 * Note that this field could be 16 bits on x86 ... ;)
182 *
183 * Architectures with slow multiplication can define
184 * WANT_PAGE_VIRTUAL in asm/page.h
185 */
186 #if defined(WANT_PAGE_VIRTUAL)
187 void *virtual; /* Kernel virtual address (NULL if
188 not kmapped, ie. highmem) */
189 #endif /* WANT_PAGE_VIRTUAL */
190
191 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
192 int _last_cpupid;
193 #endif
194
195 #ifdef CONFIG_KMSAN
196 /*
197 * KMSAN metadata for this page:
198 * - shadow page: every bit indicates whether the corresponding
199 * bit of the original page is initialized (0) or not (1);
200 * - origin page: every 4 bytes contain an id of the stack trace
201 * where the uninitialized value was created.
202 */
203 struct page *kmsan_shadow;
204 struct page *kmsan_origin;
205 #endif
206 } _struct_page_alignment;
207
208 /*
209 * struct encoded_page - a nonexistent type marking this pointer
210 *
211 * An 'encoded_page' pointer is a pointer to a regular 'struct page', but
212 * with the low bits of the pointer indicating extra context-dependent
213 * information. Not super-common, but happens in mmu_gather and mlock
214 * handling, and this acts as a type system check on that use.
215 *
216 * We only really have two guaranteed bits in general, although you could
217 * play with 'struct page' alignment (see CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
218 * for more.
219 *
220 * Use the supplied helper functions to endcode/decode the pointer and bits.
221 */
222 struct encoded_page;
223 #define ENCODE_PAGE_BITS 3ul
encode_page(struct page * page,unsigned long flags)224 static __always_inline struct encoded_page *encode_page(struct page *page, unsigned long flags)
225 {
226 BUILD_BUG_ON(flags > ENCODE_PAGE_BITS);
227 return (struct encoded_page *)(flags | (unsigned long)page);
228 }
229
encoded_page_flags(struct encoded_page * page)230 static inline unsigned long encoded_page_flags(struct encoded_page *page)
231 {
232 return ENCODE_PAGE_BITS & (unsigned long)page;
233 }
234
encoded_page_ptr(struct encoded_page * page)235 static inline struct page *encoded_page_ptr(struct encoded_page *page)
236 {
237 return (struct page *)(~ENCODE_PAGE_BITS & (unsigned long)page);
238 }
239
240 /*
241 * A swap entry has to fit into a "unsigned long", as the entry is hidden
242 * in the "index" field of the swapper address space.
243 */
244 typedef struct {
245 unsigned long val;
246 } swp_entry_t;
247
248 /**
249 * struct folio - Represents a contiguous set of bytes.
250 * @flags: Identical to the page flags.
251 * @lru: Least Recently Used list; tracks how recently this folio was used.
252 * @mlock_count: Number of times this folio has been pinned by mlock().
253 * @mapping: The file this page belongs to, or refers to the anon_vma for
254 * anonymous memory.
255 * @index: Offset within the file, in units of pages. For anonymous memory,
256 * this is the index from the beginning of the mmap.
257 * @private: Filesystem per-folio data (see folio_attach_private()).
258 * @swap: Used for swp_entry_t if folio_test_swapcache().
259 * @_mapcount: Do not access this member directly. Use folio_mapcount() to
260 * find out how many times this folio is mapped by userspace.
261 * @_refcount: Do not access this member directly. Use folio_ref_count()
262 * to find how many references there are to this folio.
263 * @memcg_data: Memory Control Group data.
264 * @virtual: Virtual address in the kernel direct map.
265 * @_last_cpupid: IDs of last CPU and last process that accessed the folio.
266 * @_entire_mapcount: Do not use directly, call folio_entire_mapcount().
267 * @_nr_pages_mapped: Do not use directly, call folio_mapcount().
268 * @_pincount: Do not use directly, call folio_maybe_dma_pinned().
269 * @_folio_nr_pages: Do not use directly, call folio_nr_pages().
270 * @_hugetlb_subpool: Do not use directly, use accessor in hugetlb.h.
271 * @_hugetlb_cgroup: Do not use directly, use accessor in hugetlb_cgroup.h.
272 * @_hugetlb_cgroup_rsvd: Do not use directly, use accessor in hugetlb_cgroup.h.
273 * @_hugetlb_hwpoison: Do not use directly, call raw_hwp_list_head().
274 * @_deferred_list: Folios to be split under memory pressure.
275 *
276 * A folio is a physically, virtually and logically contiguous set
277 * of bytes. It is a power-of-two in size, and it is aligned to that
278 * same power-of-two. It is at least as large as %PAGE_SIZE. If it is
279 * in the page cache, it is at a file offset which is a multiple of that
280 * power-of-two. It may be mapped into userspace at an address which is
281 * at an arbitrary page offset, but its kernel virtual address is aligned
282 * to its size.
283 */
284 struct folio {
285 /* private: don't document the anon union */
286 union {
287 struct {
288 /* public: */
289 unsigned long flags;
290 union {
291 struct list_head lru;
292 /* private: avoid cluttering the output */
293 struct {
294 void *__filler;
295 /* public: */
296 unsigned int mlock_count;
297 /* private: */
298 };
299 /* public: */
300 };
301 struct address_space *mapping;
302 pgoff_t index;
303 union {
304 void *private;
305 swp_entry_t swap;
306 };
307 atomic_t _mapcount;
308 atomic_t _refcount;
309 #ifdef CONFIG_MEMCG
310 unsigned long memcg_data;
311 #endif
312 #if defined(WANT_PAGE_VIRTUAL)
313 void *virtual;
314 #endif
315 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
316 int _last_cpupid;
317 #endif
318 /* private: the union with struct page is transitional */
319 };
320 struct page page;
321 };
322 union {
323 struct {
324 unsigned long _flags_1;
325 unsigned long _head_1;
326 unsigned long _folio_avail;
327 /* public: */
328 atomic_t _entire_mapcount;
329 atomic_t _nr_pages_mapped;
330 atomic_t _pincount;
331 #ifdef CONFIG_64BIT
332 unsigned int _folio_nr_pages;
333 #endif
334 /* private: the union with struct page is transitional */
335 };
336 struct page __page_1;
337 };
338 union {
339 struct {
340 unsigned long _flags_2;
341 unsigned long _head_2;
342 /* public: */
343 void *_hugetlb_subpool;
344 void *_hugetlb_cgroup;
345 void *_hugetlb_cgroup_rsvd;
346 void *_hugetlb_hwpoison;
347 /* private: the union with struct page is transitional */
348 };
349 struct {
350 unsigned long _flags_2a;
351 unsigned long _head_2a;
352 /* public: */
353 struct list_head _deferred_list;
354 /* private: the union with struct page is transitional */
355 };
356 struct page __page_2;
357 };
358 };
359
360 #define FOLIO_MATCH(pg, fl) \
361 static_assert(offsetof(struct page, pg) == offsetof(struct folio, fl))
362 FOLIO_MATCH(flags, flags);
363 FOLIO_MATCH(lru, lru);
364 FOLIO_MATCH(mapping, mapping);
365 FOLIO_MATCH(compound_head, lru);
366 FOLIO_MATCH(index, index);
367 FOLIO_MATCH(private, private);
368 FOLIO_MATCH(_mapcount, _mapcount);
369 FOLIO_MATCH(_refcount, _refcount);
370 #ifdef CONFIG_MEMCG
371 FOLIO_MATCH(memcg_data, memcg_data);
372 #endif
373 #if defined(WANT_PAGE_VIRTUAL)
374 FOLIO_MATCH(virtual, virtual);
375 #endif
376 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
377 FOLIO_MATCH(_last_cpupid, _last_cpupid);
378 #endif
379 #undef FOLIO_MATCH
380 #define FOLIO_MATCH(pg, fl) \
381 static_assert(offsetof(struct folio, fl) == \
382 offsetof(struct page, pg) + sizeof(struct page))
383 FOLIO_MATCH(flags, _flags_1);
384 FOLIO_MATCH(compound_head, _head_1);
385 #undef FOLIO_MATCH
386 #define FOLIO_MATCH(pg, fl) \
387 static_assert(offsetof(struct folio, fl) == \
388 offsetof(struct page, pg) + 2 * sizeof(struct page))
389 FOLIO_MATCH(flags, _flags_2);
390 FOLIO_MATCH(compound_head, _head_2);
391 FOLIO_MATCH(flags, _flags_2a);
392 FOLIO_MATCH(compound_head, _head_2a);
393 #undef FOLIO_MATCH
394
395 /**
396 * struct ptdesc - Memory descriptor for page tables.
397 * @__page_flags: Same as page flags. Unused for page tables.
398 * @pt_rcu_head: For freeing page table pages.
399 * @pt_list: List of used page tables. Used for s390 and x86.
400 * @_pt_pad_1: Padding that aliases with page's compound head.
401 * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs.
402 * @__page_mapping: Aliases with page->mapping. Unused for page tables.
403 * @pt_mm: Used for x86 pgds.
404 * @pt_frag_refcount: For fragmented page table tracking. Powerpc only.
405 * @_pt_pad_2: Padding to ensure proper alignment.
406 * @ptl: Lock for the page table.
407 * @__page_type: Same as page->page_type. Unused for page tables.
408 * @__page_refcount: Same as page refcount.
409 * @pt_memcg_data: Memcg data. Tracked for page tables here.
410 *
411 * This struct overlays struct page for now. Do not modify without a good
412 * understanding of the issues.
413 */
414 struct ptdesc {
415 unsigned long __page_flags;
416
417 union {
418 struct rcu_head pt_rcu_head;
419 struct list_head pt_list;
420 struct {
421 unsigned long _pt_pad_1;
422 pgtable_t pmd_huge_pte;
423 };
424 };
425 unsigned long __page_mapping;
426
427 union {
428 struct mm_struct *pt_mm;
429 atomic_t pt_frag_refcount;
430 };
431
432 union {
433 unsigned long _pt_pad_2;
434 #if ALLOC_SPLIT_PTLOCKS
435 spinlock_t *ptl;
436 #else
437 spinlock_t ptl;
438 #endif
439 };
440 unsigned int __page_type;
441 atomic_t __page_refcount;
442 #ifdef CONFIG_MEMCG
443 unsigned long pt_memcg_data;
444 #endif
445 };
446
447 #define TABLE_MATCH(pg, pt) \
448 static_assert(offsetof(struct page, pg) == offsetof(struct ptdesc, pt))
449 TABLE_MATCH(flags, __page_flags);
450 TABLE_MATCH(compound_head, pt_list);
451 TABLE_MATCH(compound_head, _pt_pad_1);
452 TABLE_MATCH(mapping, __page_mapping);
453 TABLE_MATCH(rcu_head, pt_rcu_head);
454 TABLE_MATCH(page_type, __page_type);
455 TABLE_MATCH(_refcount, __page_refcount);
456 #ifdef CONFIG_MEMCG
457 TABLE_MATCH(memcg_data, pt_memcg_data);
458 #endif
459 #undef TABLE_MATCH
460 static_assert(sizeof(struct ptdesc) <= sizeof(struct page));
461
462 #define ptdesc_page(pt) (_Generic((pt), \
463 const struct ptdesc *: (const struct page *)(pt), \
464 struct ptdesc *: (struct page *)(pt)))
465
466 #define ptdesc_folio(pt) (_Generic((pt), \
467 const struct ptdesc *: (const struct folio *)(pt), \
468 struct ptdesc *: (struct folio *)(pt)))
469
470 #define page_ptdesc(p) (_Generic((p), \
471 const struct page *: (const struct ptdesc *)(p), \
472 struct page *: (struct ptdesc *)(p)))
473
474 /*
475 * Used for sizing the vmemmap region on some architectures
476 */
477 #define STRUCT_PAGE_MAX_SHIFT (order_base_2(sizeof(struct page)))
478
479 #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK)
480 #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE)
481
482 /*
483 * page_private can be used on tail pages. However, PagePrivate is only
484 * checked by the VM on the head page. So page_private on the tail pages
485 * should be used for data that's ancillary to the head page (eg attaching
486 * buffer heads to tail pages after attaching buffer heads to the head page)
487 */
488 #define page_private(page) ((page)->private)
489
set_page_private(struct page * page,unsigned long private)490 static inline void set_page_private(struct page *page, unsigned long private)
491 {
492 page->private = private;
493 }
494
folio_get_private(struct folio * folio)495 static inline void *folio_get_private(struct folio *folio)
496 {
497 return folio->private;
498 }
499
500 struct page_frag_cache {
501 void * va;
502 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
503 __u16 offset;
504 __u16 size;
505 #else
506 __u32 offset;
507 #endif
508 /* we maintain a pagecount bias, so that we dont dirty cache line
509 * containing page->_refcount every time we allocate a fragment.
510 */
511 unsigned int pagecnt_bias;
512 bool pfmemalloc;
513 };
514
515 typedef unsigned long vm_flags_t;
516
517 /*
518 * A region containing a mapping of a non-memory backed file under NOMMU
519 * conditions. These are held in a global tree and are pinned by the VMAs that
520 * map parts of them.
521 */
522 struct vm_region {
523 struct rb_node vm_rb; /* link in global region tree */
524 vm_flags_t vm_flags; /* VMA vm_flags */
525 unsigned long vm_start; /* start address of region */
526 unsigned long vm_end; /* region initialised to here */
527 unsigned long vm_top; /* region allocated to here */
528 unsigned long vm_pgoff; /* the offset in vm_file corresponding to vm_start */
529 struct file *vm_file; /* the backing file or NULL */
530
531 int vm_usage; /* region usage count (access under nommu_region_sem) */
532 bool vm_icache_flushed : 1; /* true if the icache has been flushed for
533 * this region */
534 };
535
536 #ifdef CONFIG_USERFAULTFD
537 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, })
538 struct vm_userfaultfd_ctx {
539 struct userfaultfd_ctx *ctx;
540 };
541 #else /* CONFIG_USERFAULTFD */
542 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
543 struct vm_userfaultfd_ctx {};
544 #endif /* CONFIG_USERFAULTFD */
545
546 struct anon_vma_name {
547 struct kref kref;
548 /* The name needs to be at the end because it is dynamically sized. */
549 char name[];
550 };
551
552 #ifdef CONFIG_ANON_VMA_NAME
553 /*
554 * mmap_lock should be read-locked when calling anon_vma_name(). Caller should
555 * either keep holding the lock while using the returned pointer or it should
556 * raise anon_vma_name refcount before releasing the lock.
557 */
558 struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma);
559 struct anon_vma_name *anon_vma_name_alloc(const char *name);
560 void anon_vma_name_free(struct kref *kref);
561 #else /* CONFIG_ANON_VMA_NAME */
anon_vma_name(struct vm_area_struct * vma)562 static inline struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
563 {
564 return NULL;
565 }
566
anon_vma_name_alloc(const char * name)567 static inline struct anon_vma_name *anon_vma_name_alloc(const char *name)
568 {
569 return NULL;
570 }
571 #endif
572
573 struct vma_lock {
574 struct rw_semaphore lock;
575 };
576
577 struct vma_numab_state {
578 /*
579 * Initialised as time in 'jiffies' after which VMA
580 * should be scanned. Delays first scan of new VMA by at
581 * least sysctl_numa_balancing_scan_delay:
582 */
583 unsigned long next_scan;
584
585 /*
586 * Time in jiffies when pids_active[] is reset to
587 * detect phase change behaviour:
588 */
589 unsigned long pids_active_reset;
590
591 /*
592 * Approximate tracking of PIDs that trapped a NUMA hinting
593 * fault. May produce false positives due to hash collisions.
594 *
595 * [0] Previous PID tracking
596 * [1] Current PID tracking
597 *
598 * Window moves after next_pid_reset has expired approximately
599 * every VMA_PID_RESET_PERIOD jiffies:
600 */
601 unsigned long pids_active[2];
602
603 /* MM scan sequence ID when scan first started after VMA creation */
604 int start_scan_seq;
605
606 /*
607 * MM scan sequence ID when the VMA was last completely scanned.
608 * A VMA is not eligible for scanning if prev_scan_seq == numa_scan_seq
609 */
610 int prev_scan_seq;
611 };
612
613 /*
614 * This struct describes a virtual memory area. There is one of these
615 * per VM-area/task. A VM area is any part of the process virtual memory
616 * space that has a special rule for the page-fault handlers (ie a shared
617 * library, the executable area etc).
618 */
619 struct vm_area_struct {
620 /* The first cache line has the info for VMA tree walking. */
621
622 union {
623 struct {
624 /* VMA covers [vm_start; vm_end) addresses within mm */
625 unsigned long vm_start;
626 unsigned long vm_end;
627 };
628 #ifdef CONFIG_PER_VMA_LOCK
629 struct rcu_head vm_rcu; /* Used for deferred freeing. */
630 #endif
631 };
632
633 struct mm_struct *vm_mm; /* The address space we belong to. */
634 pgprot_t vm_page_prot; /* Access permissions of this VMA. */
635
636 /*
637 * Flags, see mm.h.
638 * To modify use vm_flags_{init|reset|set|clear|mod} functions.
639 */
640 union {
641 const vm_flags_t vm_flags;
642 vm_flags_t __private __vm_flags;
643 };
644
645 #ifdef CONFIG_PER_VMA_LOCK
646 /*
647 * Can only be written (using WRITE_ONCE()) while holding both:
648 * - mmap_lock (in write mode)
649 * - vm_lock->lock (in write mode)
650 * Can be read reliably while holding one of:
651 * - mmap_lock (in read or write mode)
652 * - vm_lock->lock (in read or write mode)
653 * Can be read unreliably (using READ_ONCE()) for pessimistic bailout
654 * while holding nothing (except RCU to keep the VMA struct allocated).
655 *
656 * This sequence counter is explicitly allowed to overflow; sequence
657 * counter reuse can only lead to occasional unnecessary use of the
658 * slowpath.
659 */
660 int vm_lock_seq;
661 struct vma_lock *vm_lock;
662
663 /* Flag to indicate areas detached from the mm->mm_mt tree */
664 bool detached;
665 #endif
666
667 /*
668 * For areas with an address space and backing store,
669 * linkage into the address_space->i_mmap interval tree.
670 *
671 */
672 struct {
673 struct rb_node rb;
674 unsigned long rb_subtree_last;
675 } shared;
676
677 /*
678 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
679 * list, after a COW of one of the file pages. A MAP_SHARED vma
680 * can only be in the i_mmap tree. An anonymous MAP_PRIVATE, stack
681 * or brk vma (with NULL file) can only be in an anon_vma list.
682 */
683 struct list_head anon_vma_chain; /* Serialized by mmap_lock &
684 * page_table_lock */
685 struct anon_vma *anon_vma; /* Serialized by page_table_lock */
686
687 /* Function pointers to deal with this struct. */
688 const struct vm_operations_struct *vm_ops;
689
690 /* Information about our backing store: */
691 unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
692 units */
693 struct file * vm_file; /* File we map to (can be NULL). */
694 void * vm_private_data; /* was vm_pte (shared mem) */
695
696 #ifdef CONFIG_ANON_VMA_NAME
697 /*
698 * For private and shared anonymous mappings, a pointer to a null
699 * terminated string containing the name given to the vma, or NULL if
700 * unnamed. Serialized by mmap_lock. Use anon_vma_name to access.
701 */
702 struct anon_vma_name *anon_name;
703 #endif
704 #ifdef CONFIG_SWAP
705 atomic_long_t swap_readahead_info;
706 #endif
707 #ifndef CONFIG_MMU
708 struct vm_region *vm_region; /* NOMMU mapping region */
709 #endif
710 #ifdef CONFIG_NUMA
711 struct mempolicy *vm_policy; /* NUMA policy for the VMA */
712 #endif
713 #ifdef CONFIG_NUMA_BALANCING
714 struct vma_numab_state *numab_state; /* NUMA Balancing state */
715 #endif
716 struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
717 } __randomize_layout;
718
719 #ifdef CONFIG_NUMA
720 #define vma_policy(vma) ((vma)->vm_policy)
721 #else
722 #define vma_policy(vma) NULL
723 #endif
724
725 #ifdef CONFIG_SCHED_MM_CID
726 struct mm_cid {
727 u64 time;
728 int cid;
729 };
730 #endif
731
732 struct kioctx_table;
733 struct iommu_mm_data;
734 struct mm_struct {
735 struct {
736 /*
737 * Fields which are often written to are placed in a separate
738 * cache line.
739 */
740 struct {
741 /**
742 * @mm_count: The number of references to &struct
743 * mm_struct (@mm_users count as 1).
744 *
745 * Use mmgrab()/mmdrop() to modify. When this drops to
746 * 0, the &struct mm_struct is freed.
747 */
748 atomic_t mm_count;
749 } ____cacheline_aligned_in_smp;
750
751 struct maple_tree mm_mt;
752 #ifdef CONFIG_MMU
753 unsigned long (*get_unmapped_area) (struct file *filp,
754 unsigned long addr, unsigned long len,
755 unsigned long pgoff, unsigned long flags);
756 #endif
757 unsigned long mmap_base; /* base of mmap area */
758 unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */
759 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
760 /* Base addresses for compatible mmap() */
761 unsigned long mmap_compat_base;
762 unsigned long mmap_compat_legacy_base;
763 #endif
764 unsigned long task_size; /* size of task vm space */
765 pgd_t * pgd;
766
767 #ifdef CONFIG_MEMBARRIER
768 /**
769 * @membarrier_state: Flags controlling membarrier behavior.
770 *
771 * This field is close to @pgd to hopefully fit in the same
772 * cache-line, which needs to be touched by switch_mm().
773 */
774 atomic_t membarrier_state;
775 #endif
776
777 /**
778 * @mm_users: The number of users including userspace.
779 *
780 * Use mmget()/mmget_not_zero()/mmput() to modify. When this
781 * drops to 0 (i.e. when the task exits and there are no other
782 * temporary reference holders), we also release a reference on
783 * @mm_count (which may then free the &struct mm_struct if
784 * @mm_count also drops to 0).
785 */
786 atomic_t mm_users;
787
788 #ifdef CONFIG_SCHED_MM_CID
789 /**
790 * @pcpu_cid: Per-cpu current cid.
791 *
792 * Keep track of the currently allocated mm_cid for each cpu.
793 * The per-cpu mm_cid values are serialized by their respective
794 * runqueue locks.
795 */
796 struct mm_cid __percpu *pcpu_cid;
797 /*
798 * @mm_cid_next_scan: Next mm_cid scan (in jiffies).
799 *
800 * When the next mm_cid scan is due (in jiffies).
801 */
802 unsigned long mm_cid_next_scan;
803 #endif
804 #ifdef CONFIG_MMU
805 atomic_long_t pgtables_bytes; /* size of all page tables */
806 #endif
807 int map_count; /* number of VMAs */
808
809 spinlock_t page_table_lock; /* Protects page tables and some
810 * counters
811 */
812 /*
813 * With some kernel config, the current mmap_lock's offset
814 * inside 'mm_struct' is at 0x120, which is very optimal, as
815 * its two hot fields 'count' and 'owner' sit in 2 different
816 * cachelines, and when mmap_lock is highly contended, both
817 * of the 2 fields will be accessed frequently, current layout
818 * will help to reduce cache bouncing.
819 *
820 * So please be careful with adding new fields before
821 * mmap_lock, which can easily push the 2 fields into one
822 * cacheline.
823 */
824 struct rw_semaphore mmap_lock;
825
826 struct list_head mmlist; /* List of maybe swapped mm's. These
827 * are globally strung together off
828 * init_mm.mmlist, and are protected
829 * by mmlist_lock
830 */
831 #ifdef CONFIG_PER_VMA_LOCK
832 /*
833 * This field has lock-like semantics, meaning it is sometimes
834 * accessed with ACQUIRE/RELEASE semantics.
835 * Roughly speaking, incrementing the sequence number is
836 * equivalent to releasing locks on VMAs; reading the sequence
837 * number can be part of taking a read lock on a VMA.
838 *
839 * Can be modified under write mmap_lock using RELEASE
840 * semantics.
841 * Can be read with no other protection when holding write
842 * mmap_lock.
843 * Can be read with ACQUIRE semantics if not holding write
844 * mmap_lock.
845 */
846 int mm_lock_seq;
847 #endif
848
849
850 unsigned long hiwater_rss; /* High-watermark of RSS usage */
851 unsigned long hiwater_vm; /* High-water virtual memory usage */
852
853 unsigned long total_vm; /* Total pages mapped */
854 unsigned long locked_vm; /* Pages that have PG_mlocked set */
855 atomic64_t pinned_vm; /* Refcount permanently increased */
856 unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
857 unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
858 unsigned long stack_vm; /* VM_STACK */
859 unsigned long def_flags;
860
861 /**
862 * @write_protect_seq: Locked when any thread is write
863 * protecting pages mapped by this mm to enforce a later COW,
864 * for instance during page table copying for fork().
865 */
866 seqcount_t write_protect_seq;
867
868 spinlock_t arg_lock; /* protect the below fields */
869
870 unsigned long start_code, end_code, start_data, end_data;
871 unsigned long start_brk, brk, start_stack;
872 unsigned long arg_start, arg_end, env_start, env_end;
873
874 unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
875
876 struct percpu_counter rss_stat[NR_MM_COUNTERS];
877
878 struct linux_binfmt *binfmt;
879
880 /* Architecture-specific MM context */
881 mm_context_t context;
882
883 unsigned long flags; /* Must use atomic bitops to access */
884
885 #ifdef CONFIG_AIO
886 spinlock_t ioctx_lock;
887 struct kioctx_table __rcu *ioctx_table;
888 #endif
889 #ifdef CONFIG_MEMCG
890 /*
891 * "owner" points to a task that is regarded as the canonical
892 * user/owner of this mm. All of the following must be true in
893 * order for it to be changed:
894 *
895 * current == mm->owner
896 * current->mm != mm
897 * new_owner->mm == mm
898 * new_owner->alloc_lock is held
899 */
900 struct task_struct __rcu *owner;
901 #endif
902 struct user_namespace *user_ns;
903
904 /* store ref to file /proc/<pid>/exe symlink points to */
905 struct file __rcu *exe_file;
906 #ifdef CONFIG_MMU_NOTIFIER
907 struct mmu_notifier_subscriptions *notifier_subscriptions;
908 #endif
909 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
910 pgtable_t pmd_huge_pte; /* protected by page_table_lock */
911 #endif
912 #ifdef CONFIG_NUMA_BALANCING
913 /*
914 * numa_next_scan is the next time that PTEs will be remapped
915 * PROT_NONE to trigger NUMA hinting faults; such faults gather
916 * statistics and migrate pages to new nodes if necessary.
917 */
918 unsigned long numa_next_scan;
919
920 /* Restart point for scanning and remapping PTEs. */
921 unsigned long numa_scan_offset;
922
923 /* numa_scan_seq prevents two threads remapping PTEs. */
924 int numa_scan_seq;
925 #endif
926 /*
927 * An operation with batched TLB flushing is going on. Anything
928 * that can move process memory needs to flush the TLB when
929 * moving a PROT_NONE mapped page.
930 */
931 atomic_t tlb_flush_pending;
932 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
933 /* See flush_tlb_batched_pending() */
934 atomic_t tlb_flush_batched;
935 #endif
936 struct uprobes_state uprobes_state;
937 #ifdef CONFIG_PREEMPT_RT
938 struct rcu_head delayed_drop;
939 #endif
940 #ifdef CONFIG_HUGETLB_PAGE
941 atomic_long_t hugetlb_usage;
942 #endif
943 struct work_struct async_put_work;
944
945 #ifdef CONFIG_IOMMU_MM_DATA
946 struct iommu_mm_data *iommu_mm;
947 #endif
948 #ifdef CONFIG_KSM
949 /*
950 * Represent how many pages of this process are involved in KSM
951 * merging (not including ksm_zero_pages).
952 */
953 unsigned long ksm_merging_pages;
954 /*
955 * Represent how many pages are checked for ksm merging
956 * including merged and not merged.
957 */
958 unsigned long ksm_rmap_items;
959 /*
960 * Represent how many empty pages are merged with kernel zero
961 * pages when enabling KSM use_zero_pages.
962 */
963 unsigned long ksm_zero_pages;
964 #endif /* CONFIG_KSM */
965 #ifdef CONFIG_LRU_GEN_WALKS_MMU
966 struct {
967 /* this mm_struct is on lru_gen_mm_list */
968 struct list_head list;
969 /*
970 * Set when switching to this mm_struct, as a hint of
971 * whether it has been used since the last time per-node
972 * page table walkers cleared the corresponding bits.
973 */
974 unsigned long bitmap;
975 #ifdef CONFIG_MEMCG
976 /* points to the memcg of "owner" above */
977 struct mem_cgroup *memcg;
978 #endif
979 } lru_gen;
980 #endif /* CONFIG_LRU_GEN_WALKS_MMU */
981 } __randomize_layout;
982
983 /*
984 * The mm_cpumask needs to be at the end of mm_struct, because it
985 * is dynamically sized based on nr_cpu_ids.
986 */
987 unsigned long cpu_bitmap[];
988 };
989
990 #define MM_MT_FLAGS (MT_FLAGS_ALLOC_RANGE | MT_FLAGS_LOCK_EXTERN | \
991 MT_FLAGS_USE_RCU)
992 extern struct mm_struct init_mm;
993
994 /* Pointer magic because the dynamic array size confuses some compilers. */
mm_init_cpumask(struct mm_struct * mm)995 static inline void mm_init_cpumask(struct mm_struct *mm)
996 {
997 unsigned long cpu_bitmap = (unsigned long)mm;
998
999 cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap);
1000 cpumask_clear((struct cpumask *)cpu_bitmap);
1001 }
1002
1003 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
mm_cpumask(struct mm_struct * mm)1004 static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
1005 {
1006 return (struct cpumask *)&mm->cpu_bitmap;
1007 }
1008
1009 #ifdef CONFIG_LRU_GEN
1010
1011 struct lru_gen_mm_list {
1012 /* mm_struct list for page table walkers */
1013 struct list_head fifo;
1014 /* protects the list above */
1015 spinlock_t lock;
1016 };
1017
1018 #endif /* CONFIG_LRU_GEN */
1019
1020 #ifdef CONFIG_LRU_GEN_WALKS_MMU
1021
1022 void lru_gen_add_mm(struct mm_struct *mm);
1023 void lru_gen_del_mm(struct mm_struct *mm);
1024 void lru_gen_migrate_mm(struct mm_struct *mm);
1025
lru_gen_init_mm(struct mm_struct * mm)1026 static inline void lru_gen_init_mm(struct mm_struct *mm)
1027 {
1028 INIT_LIST_HEAD(&mm->lru_gen.list);
1029 mm->lru_gen.bitmap = 0;
1030 #ifdef CONFIG_MEMCG
1031 mm->lru_gen.memcg = NULL;
1032 #endif
1033 }
1034
lru_gen_use_mm(struct mm_struct * mm)1035 static inline void lru_gen_use_mm(struct mm_struct *mm)
1036 {
1037 /*
1038 * When the bitmap is set, page reclaim knows this mm_struct has been
1039 * used since the last time it cleared the bitmap. So it might be worth
1040 * walking the page tables of this mm_struct to clear the accessed bit.
1041 */
1042 WRITE_ONCE(mm->lru_gen.bitmap, -1);
1043 }
1044
1045 #else /* !CONFIG_LRU_GEN_WALKS_MMU */
1046
lru_gen_add_mm(struct mm_struct * mm)1047 static inline void lru_gen_add_mm(struct mm_struct *mm)
1048 {
1049 }
1050
lru_gen_del_mm(struct mm_struct * mm)1051 static inline void lru_gen_del_mm(struct mm_struct *mm)
1052 {
1053 }
1054
lru_gen_migrate_mm(struct mm_struct * mm)1055 static inline void lru_gen_migrate_mm(struct mm_struct *mm)
1056 {
1057 }
1058
lru_gen_init_mm(struct mm_struct * mm)1059 static inline void lru_gen_init_mm(struct mm_struct *mm)
1060 {
1061 }
1062
lru_gen_use_mm(struct mm_struct * mm)1063 static inline void lru_gen_use_mm(struct mm_struct *mm)
1064 {
1065 }
1066
1067 #endif /* CONFIG_LRU_GEN_WALKS_MMU */
1068
1069 struct vma_iterator {
1070 struct ma_state mas;
1071 };
1072
1073 #define VMA_ITERATOR(name, __mm, __addr) \
1074 struct vma_iterator name = { \
1075 .mas = { \
1076 .tree = &(__mm)->mm_mt, \
1077 .index = __addr, \
1078 .node = NULL, \
1079 .status = ma_start, \
1080 }, \
1081 }
1082
vma_iter_init(struct vma_iterator * vmi,struct mm_struct * mm,unsigned long addr)1083 static inline void vma_iter_init(struct vma_iterator *vmi,
1084 struct mm_struct *mm, unsigned long addr)
1085 {
1086 mas_init(&vmi->mas, &mm->mm_mt, addr);
1087 }
1088
1089 #ifdef CONFIG_SCHED_MM_CID
1090
1091 enum mm_cid_state {
1092 MM_CID_UNSET = -1U, /* Unset state has lazy_put flag set. */
1093 MM_CID_LAZY_PUT = (1U << 31),
1094 };
1095
mm_cid_is_unset(int cid)1096 static inline bool mm_cid_is_unset(int cid)
1097 {
1098 return cid == MM_CID_UNSET;
1099 }
1100
mm_cid_is_lazy_put(int cid)1101 static inline bool mm_cid_is_lazy_put(int cid)
1102 {
1103 return !mm_cid_is_unset(cid) && (cid & MM_CID_LAZY_PUT);
1104 }
1105
mm_cid_is_valid(int cid)1106 static inline bool mm_cid_is_valid(int cid)
1107 {
1108 return !(cid & MM_CID_LAZY_PUT);
1109 }
1110
mm_cid_set_lazy_put(int cid)1111 static inline int mm_cid_set_lazy_put(int cid)
1112 {
1113 return cid | MM_CID_LAZY_PUT;
1114 }
1115
mm_cid_clear_lazy_put(int cid)1116 static inline int mm_cid_clear_lazy_put(int cid)
1117 {
1118 return cid & ~MM_CID_LAZY_PUT;
1119 }
1120
1121 /* Accessor for struct mm_struct's cidmask. */
mm_cidmask(struct mm_struct * mm)1122 static inline cpumask_t *mm_cidmask(struct mm_struct *mm)
1123 {
1124 unsigned long cid_bitmap = (unsigned long)mm;
1125
1126 cid_bitmap += offsetof(struct mm_struct, cpu_bitmap);
1127 /* Skip cpu_bitmap */
1128 cid_bitmap += cpumask_size();
1129 return (struct cpumask *)cid_bitmap;
1130 }
1131
mm_init_cid(struct mm_struct * mm)1132 static inline void mm_init_cid(struct mm_struct *mm)
1133 {
1134 int i;
1135
1136 for_each_possible_cpu(i) {
1137 struct mm_cid *pcpu_cid = per_cpu_ptr(mm->pcpu_cid, i);
1138
1139 pcpu_cid->cid = MM_CID_UNSET;
1140 pcpu_cid->time = 0;
1141 }
1142 cpumask_clear(mm_cidmask(mm));
1143 }
1144
mm_alloc_cid(struct mm_struct * mm)1145 static inline int mm_alloc_cid(struct mm_struct *mm)
1146 {
1147 mm->pcpu_cid = alloc_percpu(struct mm_cid);
1148 if (!mm->pcpu_cid)
1149 return -ENOMEM;
1150 mm_init_cid(mm);
1151 return 0;
1152 }
1153
mm_destroy_cid(struct mm_struct * mm)1154 static inline void mm_destroy_cid(struct mm_struct *mm)
1155 {
1156 free_percpu(mm->pcpu_cid);
1157 mm->pcpu_cid = NULL;
1158 }
1159
mm_cid_size(void)1160 static inline unsigned int mm_cid_size(void)
1161 {
1162 return cpumask_size();
1163 }
1164 #else /* CONFIG_SCHED_MM_CID */
mm_init_cid(struct mm_struct * mm)1165 static inline void mm_init_cid(struct mm_struct *mm) { }
mm_alloc_cid(struct mm_struct * mm)1166 static inline int mm_alloc_cid(struct mm_struct *mm) { return 0; }
mm_destroy_cid(struct mm_struct * mm)1167 static inline void mm_destroy_cid(struct mm_struct *mm) { }
mm_cid_size(void)1168 static inline unsigned int mm_cid_size(void)
1169 {
1170 return 0;
1171 }
1172 #endif /* CONFIG_SCHED_MM_CID */
1173
1174 struct mmu_gather;
1175 extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm);
1176 extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm);
1177 extern void tlb_finish_mmu(struct mmu_gather *tlb);
1178
1179 struct vm_fault;
1180
1181 /**
1182 * typedef vm_fault_t - Return type for page fault handlers.
1183 *
1184 * Page fault handlers return a bitmask of %VM_FAULT values.
1185 */
1186 typedef __bitwise unsigned int vm_fault_t;
1187
1188 /**
1189 * enum vm_fault_reason - Page fault handlers return a bitmask of
1190 * these values to tell the core VM what happened when handling the
1191 * fault. Used to decide whether a process gets delivered SIGBUS or
1192 * just gets major/minor fault counters bumped up.
1193 *
1194 * @VM_FAULT_OOM: Out Of Memory
1195 * @VM_FAULT_SIGBUS: Bad access
1196 * @VM_FAULT_MAJOR: Page read from storage
1197 * @VM_FAULT_HWPOISON: Hit poisoned small page
1198 * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
1199 * in upper bits
1200 * @VM_FAULT_SIGSEGV: segmentation fault
1201 * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
1202 * @VM_FAULT_LOCKED: ->fault locked the returned page
1203 * @VM_FAULT_RETRY: ->fault blocked, must retry
1204 * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
1205 * @VM_FAULT_DONE_COW: ->fault has fully handled COW
1206 * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
1207 * fsync() to complete (for synchronous page faults
1208 * in DAX)
1209 * @VM_FAULT_COMPLETED: ->fault completed, meanwhile mmap lock released
1210 * @VM_FAULT_HINDEX_MASK: mask HINDEX value
1211 *
1212 */
1213 enum vm_fault_reason {
1214 VM_FAULT_OOM = (__force vm_fault_t)0x000001,
1215 VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
1216 VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
1217 VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
1218 VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
1219 VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
1220 VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
1221 VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
1222 VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
1223 VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
1224 VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
1225 VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
1226 VM_FAULT_COMPLETED = (__force vm_fault_t)0x004000,
1227 VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
1228 };
1229
1230 /* Encode hstate index for a hwpoisoned large page */
1231 #define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
1232 #define VM_FAULT_GET_HINDEX(x) (((__force unsigned int)(x) >> 16) & 0xf)
1233
1234 #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
1235 VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
1236 VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
1237
1238 #define VM_FAULT_RESULT_TRACE \
1239 { VM_FAULT_OOM, "OOM" }, \
1240 { VM_FAULT_SIGBUS, "SIGBUS" }, \
1241 { VM_FAULT_MAJOR, "MAJOR" }, \
1242 { VM_FAULT_HWPOISON, "HWPOISON" }, \
1243 { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
1244 { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
1245 { VM_FAULT_NOPAGE, "NOPAGE" }, \
1246 { VM_FAULT_LOCKED, "LOCKED" }, \
1247 { VM_FAULT_RETRY, "RETRY" }, \
1248 { VM_FAULT_FALLBACK, "FALLBACK" }, \
1249 { VM_FAULT_DONE_COW, "DONE_COW" }, \
1250 { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \
1251 { VM_FAULT_COMPLETED, "COMPLETED" }
1252
1253 struct vm_special_mapping {
1254 const char *name; /* The name, e.g. "[vdso]". */
1255
1256 /*
1257 * If .fault is not provided, this points to a
1258 * NULL-terminated array of pages that back the special mapping.
1259 *
1260 * This must not be NULL unless .fault is provided.
1261 */
1262 struct page **pages;
1263
1264 /*
1265 * If non-NULL, then this is called to resolve page faults
1266 * on the special mapping. If used, .pages is not checked.
1267 */
1268 vm_fault_t (*fault)(const struct vm_special_mapping *sm,
1269 struct vm_area_struct *vma,
1270 struct vm_fault *vmf);
1271
1272 int (*mremap)(const struct vm_special_mapping *sm,
1273 struct vm_area_struct *new_vma);
1274 };
1275
1276 enum tlb_flush_reason {
1277 TLB_FLUSH_ON_TASK_SWITCH,
1278 TLB_REMOTE_SHOOTDOWN,
1279 TLB_LOCAL_SHOOTDOWN,
1280 TLB_LOCAL_MM_SHOOTDOWN,
1281 TLB_REMOTE_SEND_IPI,
1282 NR_TLB_FLUSH_REASONS,
1283 };
1284
1285 /**
1286 * enum fault_flag - Fault flag definitions.
1287 * @FAULT_FLAG_WRITE: Fault was a write fault.
1288 * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE.
1289 * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked.
1290 * @FAULT_FLAG_RETRY_NOWAIT: Don't drop mmap_lock and wait when retrying.
1291 * @FAULT_FLAG_KILLABLE: The fault task is in SIGKILL killable region.
1292 * @FAULT_FLAG_TRIED: The fault has been tried once.
1293 * @FAULT_FLAG_USER: The fault originated in userspace.
1294 * @FAULT_FLAG_REMOTE: The fault is not for current task/mm.
1295 * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch.
1296 * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals.
1297 * @FAULT_FLAG_UNSHARE: The fault is an unsharing request to break COW in a
1298 * COW mapping, making sure that an exclusive anon page is
1299 * mapped after the fault.
1300 * @FAULT_FLAG_ORIG_PTE_VALID: whether the fault has vmf->orig_pte cached.
1301 * We should only access orig_pte if this flag set.
1302 * @FAULT_FLAG_VMA_LOCK: The fault is handled under VMA lock.
1303 *
1304 * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify
1305 * whether we would allow page faults to retry by specifying these two
1306 * fault flags correctly. Currently there can be three legal combinations:
1307 *
1308 * (a) ALLOW_RETRY and !TRIED: this means the page fault allows retry, and
1309 * this is the first try
1310 *
1311 * (b) ALLOW_RETRY and TRIED: this means the page fault allows retry, and
1312 * we've already tried at least once
1313 *
1314 * (c) !ALLOW_RETRY and !TRIED: this means the page fault does not allow retry
1315 *
1316 * The unlisted combination (!ALLOW_RETRY && TRIED) is illegal and should never
1317 * be used. Note that page faults can be allowed to retry for multiple times,
1318 * in which case we'll have an initial fault with flags (a) then later on
1319 * continuous faults with flags (b). We should always try to detect pending
1320 * signals before a retry to make sure the continuous page faults can still be
1321 * interrupted if necessary.
1322 *
1323 * The combination FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE is illegal.
1324 * FAULT_FLAG_UNSHARE is ignored and treated like an ordinary read fault when
1325 * applied to mappings that are not COW mappings.
1326 */
1327 enum fault_flag {
1328 FAULT_FLAG_WRITE = 1 << 0,
1329 FAULT_FLAG_MKWRITE = 1 << 1,
1330 FAULT_FLAG_ALLOW_RETRY = 1 << 2,
1331 FAULT_FLAG_RETRY_NOWAIT = 1 << 3,
1332 FAULT_FLAG_KILLABLE = 1 << 4,
1333 FAULT_FLAG_TRIED = 1 << 5,
1334 FAULT_FLAG_USER = 1 << 6,
1335 FAULT_FLAG_REMOTE = 1 << 7,
1336 FAULT_FLAG_INSTRUCTION = 1 << 8,
1337 FAULT_FLAG_INTERRUPTIBLE = 1 << 9,
1338 FAULT_FLAG_UNSHARE = 1 << 10,
1339 FAULT_FLAG_ORIG_PTE_VALID = 1 << 11,
1340 FAULT_FLAG_VMA_LOCK = 1 << 12,
1341 };
1342
1343 typedef unsigned int __bitwise zap_flags_t;
1344
1345 /*
1346 * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each
1347 * other. Here is what they mean, and how to use them:
1348 *
1349 *
1350 * FIXME: For pages which are part of a filesystem, mappings are subject to the
1351 * lifetime enforced by the filesystem and we need guarantees that longterm
1352 * users like RDMA and V4L2 only establish mappings which coordinate usage with
1353 * the filesystem. Ideas for this coordination include revoking the longterm
1354 * pin, delaying writeback, bounce buffer page writeback, etc. As FS DAX was
1355 * added after the problem with filesystems was found FS DAX VMAs are
1356 * specifically failed. Filesystem pages are still subject to bugs and use of
1357 * FOLL_LONGTERM should be avoided on those pages.
1358 *
1359 * In the CMA case: long term pins in a CMA region would unnecessarily fragment
1360 * that region. And so, CMA attempts to migrate the page before pinning, when
1361 * FOLL_LONGTERM is specified.
1362 *
1363 * FOLL_PIN indicates that a special kind of tracking (not just page->_refcount,
1364 * but an additional pin counting system) will be invoked. This is intended for
1365 * anything that gets a page reference and then touches page data (for example,
1366 * Direct IO). This lets the filesystem know that some non-file-system entity is
1367 * potentially changing the pages' data. In contrast to FOLL_GET (whose pages
1368 * are released via put_page()), FOLL_PIN pages must be released, ultimately, by
1369 * a call to unpin_user_page().
1370 *
1371 * FOLL_PIN is similar to FOLL_GET: both of these pin pages. They use different
1372 * and separate refcounting mechanisms, however, and that means that each has
1373 * its own acquire and release mechanisms:
1374 *
1375 * FOLL_GET: get_user_pages*() to acquire, and put_page() to release.
1376 *
1377 * FOLL_PIN: pin_user_pages*() to acquire, and unpin_user_pages to release.
1378 *
1379 * FOLL_PIN and FOLL_GET are mutually exclusive for a given function call.
1380 * (The underlying pages may experience both FOLL_GET-based and FOLL_PIN-based
1381 * calls applied to them, and that's perfectly OK. This is a constraint on the
1382 * callers, not on the pages.)
1383 *
1384 * FOLL_PIN should be set internally by the pin_user_pages*() APIs, never
1385 * directly by the caller. That's in order to help avoid mismatches when
1386 * releasing pages: get_user_pages*() pages must be released via put_page(),
1387 * while pin_user_pages*() pages must be released via unpin_user_page().
1388 *
1389 * Please see Documentation/core-api/pin_user_pages.rst for more information.
1390 */
1391
1392 enum {
1393 /* check pte is writable */
1394 FOLL_WRITE = 1 << 0,
1395 /* do get_page on page */
1396 FOLL_GET = 1 << 1,
1397 /* give error on hole if it would be zero */
1398 FOLL_DUMP = 1 << 2,
1399 /* get_user_pages read/write w/o permission */
1400 FOLL_FORCE = 1 << 3,
1401 /*
1402 * if a disk transfer is needed, start the IO and return without waiting
1403 * upon it
1404 */
1405 FOLL_NOWAIT = 1 << 4,
1406 /* do not fault in pages */
1407 FOLL_NOFAULT = 1 << 5,
1408 /* check page is hwpoisoned */
1409 FOLL_HWPOISON = 1 << 6,
1410 /* don't do file mappings */
1411 FOLL_ANON = 1 << 7,
1412 /*
1413 * FOLL_LONGTERM indicates that the page will be held for an indefinite
1414 * time period _often_ under userspace control. This is in contrast to
1415 * iov_iter_get_pages(), whose usages are transient.
1416 */
1417 FOLL_LONGTERM = 1 << 8,
1418 /* split huge pmd before returning */
1419 FOLL_SPLIT_PMD = 1 << 9,
1420 /* allow returning PCI P2PDMA pages */
1421 FOLL_PCI_P2PDMA = 1 << 10,
1422 /* allow interrupts from generic signals */
1423 FOLL_INTERRUPTIBLE = 1 << 11,
1424 /*
1425 * Always honor (trigger) NUMA hinting faults.
1426 *
1427 * FOLL_WRITE implicitly honors NUMA hinting faults because a
1428 * PROT_NONE-mapped page is not writable (exceptions with FOLL_FORCE
1429 * apply). get_user_pages_fast_only() always implicitly honors NUMA
1430 * hinting faults.
1431 */
1432 FOLL_HONOR_NUMA_FAULT = 1 << 12,
1433
1434 /* See also internal only FOLL flags in mm/internal.h */
1435 };
1436
1437 #endif /* _LINUX_MM_TYPES_H */
1438