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 union { 129 /** 130 * dma_addr_upper: might require a 64-bit 131 * value on 32-bit architectures. 132 */ 133 unsigned long dma_addr_upper; 134 /** 135 * For frag page support, not supported in 136 * 32-bit architectures with 64-bit DMA. 137 */ 138 atomic_long_t pp_frag_count; 139 }; 140 }; 141 struct { /* Tail pages of compound page */ 142 unsigned long compound_head; /* Bit zero is set */ 143 }; 144 struct { /* ZONE_DEVICE pages */ 145 /** @pgmap: Points to the hosting device page map. */ 146 struct dev_pagemap *pgmap; 147 void *zone_device_data; 148 /* 149 * ZONE_DEVICE private pages are counted as being 150 * mapped so the next 3 words hold the mapping, index, 151 * and private fields from the source anonymous or 152 * page cache page while the page is migrated to device 153 * private memory. 154 * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also 155 * use the mapping, index, and private fields when 156 * pmem backed DAX files are mapped. 157 */ 158 }; 159 160 /** @rcu_head: You can use this to free a page by RCU. */ 161 struct rcu_head rcu_head; 162 }; 163 164 union { /* This union is 4 bytes in size. */ 165 /* 166 * If the page can be mapped to userspace, encodes the number 167 * of times this page is referenced by a page table. 168 */ 169 atomic_t _mapcount; 170 171 /* 172 * If the page is neither PageSlab nor mappable to userspace, 173 * the value stored here may help determine what this page 174 * is used for. See page-flags.h for a list of page types 175 * which are currently stored here. 176 */ 177 unsigned int page_type; 178 }; 179 180 /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */ 181 atomic_t _refcount; 182 183 #ifdef CONFIG_MEMCG 184 unsigned long memcg_data; 185 #endif 186 187 /* 188 * On machines where all RAM is mapped into kernel address space, 189 * we can simply calculate the virtual address. On machines with 190 * highmem some memory is mapped into kernel virtual memory 191 * dynamically, so we need a place to store that address. 192 * Note that this field could be 16 bits on x86 ... ;) 193 * 194 * Architectures with slow multiplication can define 195 * WANT_PAGE_VIRTUAL in asm/page.h 196 */ 197 #if defined(WANT_PAGE_VIRTUAL) 198 void *virtual; /* Kernel virtual address (NULL if 199 not kmapped, ie. highmem) */ 200 #endif /* WANT_PAGE_VIRTUAL */ 201 202 #ifdef CONFIG_KMSAN 203 /* 204 * KMSAN metadata for this page: 205 * - shadow page: every bit indicates whether the corresponding 206 * bit of the original page is initialized (0) or not (1); 207 * - origin page: every 4 bytes contain an id of the stack trace 208 * where the uninitialized value was created. 209 */ 210 struct page *kmsan_shadow; 211 struct page *kmsan_origin; 212 #endif 213 214 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 215 int _last_cpupid; 216 #endif 217 } _struct_page_alignment; 218 219 /* 220 * struct encoded_page - a nonexistent type marking this pointer 221 * 222 * An 'encoded_page' pointer is a pointer to a regular 'struct page', but 223 * with the low bits of the pointer indicating extra context-dependent 224 * information. Not super-common, but happens in mmu_gather and mlock 225 * handling, and this acts as a type system check on that use. 226 * 227 * We only really have two guaranteed bits in general, although you could 228 * play with 'struct page' alignment (see CONFIG_HAVE_ALIGNED_STRUCT_PAGE) 229 * for more. 230 * 231 * Use the supplied helper functions to endcode/decode the pointer and bits. 232 */ 233 struct encoded_page; 234 #define ENCODE_PAGE_BITS 3ul 235 static __always_inline struct encoded_page *encode_page(struct page *page, unsigned long flags) 236 { 237 BUILD_BUG_ON(flags > ENCODE_PAGE_BITS); 238 return (struct encoded_page *)(flags | (unsigned long)page); 239 } 240 241 static inline unsigned long encoded_page_flags(struct encoded_page *page) 242 { 243 return ENCODE_PAGE_BITS & (unsigned long)page; 244 } 245 246 static inline struct page *encoded_page_ptr(struct encoded_page *page) 247 { 248 return (struct page *)(~ENCODE_PAGE_BITS & (unsigned long)page); 249 } 250 251 /* 252 * A swap entry has to fit into a "unsigned long", as the entry is hidden 253 * in the "index" field of the swapper address space. 254 */ 255 typedef struct { 256 unsigned long val; 257 } swp_entry_t; 258 259 /** 260 * struct folio - Represents a contiguous set of bytes. 261 * @flags: Identical to the page flags. 262 * @lru: Least Recently Used list; tracks how recently this folio was used. 263 * @mlock_count: Number of times this folio has been pinned by mlock(). 264 * @mapping: The file this page belongs to, or refers to the anon_vma for 265 * anonymous memory. 266 * @index: Offset within the file, in units of pages. For anonymous memory, 267 * this is the index from the beginning of the mmap. 268 * @private: Filesystem per-folio data (see folio_attach_private()). 269 * @swap: Used for swp_entry_t if folio_test_swapcache(). 270 * @_mapcount: Do not access this member directly. Use folio_mapcount() to 271 * find out how many times this folio is mapped by userspace. 272 * @_refcount: Do not access this member directly. Use folio_ref_count() 273 * to find how many references there are to this folio. 274 * @memcg_data: Memory Control Group data. 275 * @_entire_mapcount: Do not use directly, call folio_entire_mapcount(). 276 * @_nr_pages_mapped: Do not use directly, call folio_mapcount(). 277 * @_pincount: Do not use directly, call folio_maybe_dma_pinned(). 278 * @_folio_nr_pages: Do not use directly, call folio_nr_pages(). 279 * @_hugetlb_subpool: Do not use directly, use accessor in hugetlb.h. 280 * @_hugetlb_cgroup: Do not use directly, use accessor in hugetlb_cgroup.h. 281 * @_hugetlb_cgroup_rsvd: Do not use directly, use accessor in hugetlb_cgroup.h. 282 * @_hugetlb_hwpoison: Do not use directly, call raw_hwp_list_head(). 283 * @_deferred_list: Folios to be split under memory pressure. 284 * 285 * A folio is a physically, virtually and logically contiguous set 286 * of bytes. It is a power-of-two in size, and it is aligned to that 287 * same power-of-two. It is at least as large as %PAGE_SIZE. If it is 288 * in the page cache, it is at a file offset which is a multiple of that 289 * power-of-two. It may be mapped into userspace at an address which is 290 * at an arbitrary page offset, but its kernel virtual address is aligned 291 * to its size. 292 */ 293 struct folio { 294 /* private: don't document the anon union */ 295 union { 296 struct { 297 /* public: */ 298 unsigned long flags; 299 union { 300 struct list_head lru; 301 /* private: avoid cluttering the output */ 302 struct { 303 void *__filler; 304 /* public: */ 305 unsigned int mlock_count; 306 /* private: */ 307 }; 308 /* public: */ 309 }; 310 struct address_space *mapping; 311 pgoff_t index; 312 union { 313 void *private; 314 swp_entry_t swap; 315 }; 316 atomic_t _mapcount; 317 atomic_t _refcount; 318 #ifdef CONFIG_MEMCG 319 unsigned long memcg_data; 320 #endif 321 /* private: the union with struct page is transitional */ 322 }; 323 struct page page; 324 }; 325 union { 326 struct { 327 unsigned long _flags_1; 328 unsigned long _head_1; 329 unsigned long _folio_avail; 330 /* public: */ 331 atomic_t _entire_mapcount; 332 atomic_t _nr_pages_mapped; 333 atomic_t _pincount; 334 #ifdef CONFIG_64BIT 335 unsigned int _folio_nr_pages; 336 #endif 337 /* private: the union with struct page is transitional */ 338 }; 339 struct page __page_1; 340 }; 341 union { 342 struct { 343 unsigned long _flags_2; 344 unsigned long _head_2; 345 /* public: */ 346 void *_hugetlb_subpool; 347 void *_hugetlb_cgroup; 348 void *_hugetlb_cgroup_rsvd; 349 void *_hugetlb_hwpoison; 350 /* private: the union with struct page is transitional */ 351 }; 352 struct { 353 unsigned long _flags_2a; 354 unsigned long _head_2a; 355 /* public: */ 356 struct list_head _deferred_list; 357 /* private: the union with struct page is transitional */ 358 }; 359 struct page __page_2; 360 }; 361 }; 362 363 #define FOLIO_MATCH(pg, fl) \ 364 static_assert(offsetof(struct page, pg) == offsetof(struct folio, fl)) 365 FOLIO_MATCH(flags, flags); 366 FOLIO_MATCH(lru, lru); 367 FOLIO_MATCH(mapping, mapping); 368 FOLIO_MATCH(compound_head, lru); 369 FOLIO_MATCH(index, index); 370 FOLIO_MATCH(private, private); 371 FOLIO_MATCH(_mapcount, _mapcount); 372 FOLIO_MATCH(_refcount, _refcount); 373 #ifdef CONFIG_MEMCG 374 FOLIO_MATCH(memcg_data, memcg_data); 375 #endif 376 #undef FOLIO_MATCH 377 #define FOLIO_MATCH(pg, fl) \ 378 static_assert(offsetof(struct folio, fl) == \ 379 offsetof(struct page, pg) + sizeof(struct page)) 380 FOLIO_MATCH(flags, _flags_1); 381 FOLIO_MATCH(compound_head, _head_1); 382 #undef FOLIO_MATCH 383 #define FOLIO_MATCH(pg, fl) \ 384 static_assert(offsetof(struct folio, fl) == \ 385 offsetof(struct page, pg) + 2 * sizeof(struct page)) 386 FOLIO_MATCH(flags, _flags_2); 387 FOLIO_MATCH(compound_head, _head_2); 388 FOLIO_MATCH(flags, _flags_2a); 389 FOLIO_MATCH(compound_head, _head_2a); 390 #undef FOLIO_MATCH 391 392 /** 393 * struct ptdesc - Memory descriptor for page tables. 394 * @__page_flags: Same as page flags. Unused for page tables. 395 * @pt_rcu_head: For freeing page table pages. 396 * @pt_list: List of used page tables. Used for s390 and x86. 397 * @_pt_pad_1: Padding that aliases with page's compound head. 398 * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs. 399 * @__page_mapping: Aliases with page->mapping. Unused for page tables. 400 * @pt_mm: Used for x86 pgds. 401 * @pt_frag_refcount: For fragmented page table tracking. Powerpc and s390 only. 402 * @_pt_pad_2: Padding to ensure proper alignment. 403 * @ptl: Lock for the page table. 404 * @__page_type: Same as page->page_type. Unused for page tables. 405 * @_refcount: Same as page refcount. Used for s390 page tables. 406 * @pt_memcg_data: Memcg data. Tracked for page tables here. 407 * 408 * This struct overlays struct page for now. Do not modify without a good 409 * understanding of the issues. 410 */ 411 struct ptdesc { 412 unsigned long __page_flags; 413 414 union { 415 struct rcu_head pt_rcu_head; 416 struct list_head pt_list; 417 struct { 418 unsigned long _pt_pad_1; 419 pgtable_t pmd_huge_pte; 420 }; 421 }; 422 unsigned long __page_mapping; 423 424 union { 425 struct mm_struct *pt_mm; 426 atomic_t pt_frag_refcount; 427 }; 428 429 union { 430 unsigned long _pt_pad_2; 431 #if ALLOC_SPLIT_PTLOCKS 432 spinlock_t *ptl; 433 #else 434 spinlock_t ptl; 435 #endif 436 }; 437 unsigned int __page_type; 438 atomic_t _refcount; 439 #ifdef CONFIG_MEMCG 440 unsigned long pt_memcg_data; 441 #endif 442 }; 443 444 #define TABLE_MATCH(pg, pt) \ 445 static_assert(offsetof(struct page, pg) == offsetof(struct ptdesc, pt)) 446 TABLE_MATCH(flags, __page_flags); 447 TABLE_MATCH(compound_head, pt_list); 448 TABLE_MATCH(compound_head, _pt_pad_1); 449 TABLE_MATCH(mapping, __page_mapping); 450 TABLE_MATCH(rcu_head, pt_rcu_head); 451 TABLE_MATCH(page_type, __page_type); 452 TABLE_MATCH(_refcount, _refcount); 453 #ifdef CONFIG_MEMCG 454 TABLE_MATCH(memcg_data, pt_memcg_data); 455 #endif 456 #undef TABLE_MATCH 457 static_assert(sizeof(struct ptdesc) <= sizeof(struct page)); 458 459 #define ptdesc_page(pt) (_Generic((pt), \ 460 const struct ptdesc *: (const struct page *)(pt), \ 461 struct ptdesc *: (struct page *)(pt))) 462 463 #define ptdesc_folio(pt) (_Generic((pt), \ 464 const struct ptdesc *: (const struct folio *)(pt), \ 465 struct ptdesc *: (struct folio *)(pt))) 466 467 #define page_ptdesc(p) (_Generic((p), \ 468 const struct page *: (const struct ptdesc *)(p), \ 469 struct page *: (struct ptdesc *)(p))) 470 471 /* 472 * Used for sizing the vmemmap region on some architectures 473 */ 474 #define STRUCT_PAGE_MAX_SHIFT (order_base_2(sizeof(struct page))) 475 476 #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) 477 #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE) 478 479 /* 480 * page_private can be used on tail pages. However, PagePrivate is only 481 * checked by the VM on the head page. So page_private on the tail pages 482 * should be used for data that's ancillary to the head page (eg attaching 483 * buffer heads to tail pages after attaching buffer heads to the head page) 484 */ 485 #define page_private(page) ((page)->private) 486 487 static inline void set_page_private(struct page *page, unsigned long private) 488 { 489 page->private = private; 490 } 491 492 static inline void *folio_get_private(struct folio *folio) 493 { 494 return folio->private; 495 } 496 497 struct page_frag_cache { 498 void * va; 499 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) 500 __u16 offset; 501 __u16 size; 502 #else 503 __u32 offset; 504 #endif 505 /* we maintain a pagecount bias, so that we dont dirty cache line 506 * containing page->_refcount every time we allocate a fragment. 507 */ 508 unsigned int pagecnt_bias; 509 bool pfmemalloc; 510 }; 511 512 typedef unsigned long vm_flags_t; 513 514 /* 515 * A region containing a mapping of a non-memory backed file under NOMMU 516 * conditions. These are held in a global tree and are pinned by the VMAs that 517 * map parts of them. 518 */ 519 struct vm_region { 520 struct rb_node vm_rb; /* link in global region tree */ 521 vm_flags_t vm_flags; /* VMA vm_flags */ 522 unsigned long vm_start; /* start address of region */ 523 unsigned long vm_end; /* region initialised to here */ 524 unsigned long vm_top; /* region allocated to here */ 525 unsigned long vm_pgoff; /* the offset in vm_file corresponding to vm_start */ 526 struct file *vm_file; /* the backing file or NULL */ 527 528 int vm_usage; /* region usage count (access under nommu_region_sem) */ 529 bool vm_icache_flushed : 1; /* true if the icache has been flushed for 530 * this region */ 531 }; 532 533 #ifdef CONFIG_USERFAULTFD 534 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, }) 535 struct vm_userfaultfd_ctx { 536 struct userfaultfd_ctx *ctx; 537 }; 538 #else /* CONFIG_USERFAULTFD */ 539 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {}) 540 struct vm_userfaultfd_ctx {}; 541 #endif /* CONFIG_USERFAULTFD */ 542 543 struct anon_vma_name { 544 struct kref kref; 545 /* The name needs to be at the end because it is dynamically sized. */ 546 char name[]; 547 }; 548 549 struct vma_lock { 550 struct rw_semaphore lock; 551 }; 552 553 struct vma_numab_state { 554 unsigned long next_scan; 555 unsigned long next_pid_reset; 556 unsigned long access_pids[2]; 557 }; 558 559 /* 560 * This struct describes a virtual memory area. There is one of these 561 * per VM-area/task. A VM area is any part of the process virtual memory 562 * space that has a special rule for the page-fault handlers (ie a shared 563 * library, the executable area etc). 564 */ 565 struct vm_area_struct { 566 /* The first cache line has the info for VMA tree walking. */ 567 568 union { 569 struct { 570 /* VMA covers [vm_start; vm_end) addresses within mm */ 571 unsigned long vm_start; 572 unsigned long vm_end; 573 }; 574 #ifdef CONFIG_PER_VMA_LOCK 575 struct rcu_head vm_rcu; /* Used for deferred freeing. */ 576 #endif 577 }; 578 579 struct mm_struct *vm_mm; /* The address space we belong to. */ 580 pgprot_t vm_page_prot; /* Access permissions of this VMA. */ 581 582 /* 583 * Flags, see mm.h. 584 * To modify use vm_flags_{init|reset|set|clear|mod} functions. 585 */ 586 union { 587 const vm_flags_t vm_flags; 588 vm_flags_t __private __vm_flags; 589 }; 590 591 #ifdef CONFIG_PER_VMA_LOCK 592 /* 593 * Can only be written (using WRITE_ONCE()) while holding both: 594 * - mmap_lock (in write mode) 595 * - vm_lock->lock (in write mode) 596 * Can be read reliably while holding one of: 597 * - mmap_lock (in read or write mode) 598 * - vm_lock->lock (in read or write mode) 599 * Can be read unreliably (using READ_ONCE()) for pessimistic bailout 600 * while holding nothing (except RCU to keep the VMA struct allocated). 601 * 602 * This sequence counter is explicitly allowed to overflow; sequence 603 * counter reuse can only lead to occasional unnecessary use of the 604 * slowpath. 605 */ 606 int vm_lock_seq; 607 struct vma_lock *vm_lock; 608 609 /* Flag to indicate areas detached from the mm->mm_mt tree */ 610 bool detached; 611 #endif 612 613 /* 614 * For areas with an address space and backing store, 615 * linkage into the address_space->i_mmap interval tree. 616 * 617 */ 618 struct { 619 struct rb_node rb; 620 unsigned long rb_subtree_last; 621 } shared; 622 623 /* 624 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma 625 * list, after a COW of one of the file pages. A MAP_SHARED vma 626 * can only be in the i_mmap tree. An anonymous MAP_PRIVATE, stack 627 * or brk vma (with NULL file) can only be in an anon_vma list. 628 */ 629 struct list_head anon_vma_chain; /* Serialized by mmap_lock & 630 * page_table_lock */ 631 struct anon_vma *anon_vma; /* Serialized by page_table_lock */ 632 633 /* Function pointers to deal with this struct. */ 634 const struct vm_operations_struct *vm_ops; 635 636 /* Information about our backing store: */ 637 unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE 638 units */ 639 struct file * vm_file; /* File we map to (can be NULL). */ 640 void * vm_private_data; /* was vm_pte (shared mem) */ 641 642 #ifdef CONFIG_ANON_VMA_NAME 643 /* 644 * For private and shared anonymous mappings, a pointer to a null 645 * terminated string containing the name given to the vma, or NULL if 646 * unnamed. Serialized by mmap_lock. Use anon_vma_name to access. 647 */ 648 struct anon_vma_name *anon_name; 649 #endif 650 #ifdef CONFIG_SWAP 651 atomic_long_t swap_readahead_info; 652 #endif 653 #ifndef CONFIG_MMU 654 struct vm_region *vm_region; /* NOMMU mapping region */ 655 #endif 656 #ifdef CONFIG_NUMA 657 struct mempolicy *vm_policy; /* NUMA policy for the VMA */ 658 #endif 659 #ifdef CONFIG_NUMA_BALANCING 660 struct vma_numab_state *numab_state; /* NUMA Balancing state */ 661 #endif 662 struct vm_userfaultfd_ctx vm_userfaultfd_ctx; 663 } __randomize_layout; 664 665 #ifdef CONFIG_SCHED_MM_CID 666 struct mm_cid { 667 u64 time; 668 int cid; 669 }; 670 #endif 671 672 struct kioctx_table; 673 struct mm_struct { 674 struct { 675 /* 676 * Fields which are often written to are placed in a separate 677 * cache line. 678 */ 679 struct { 680 /** 681 * @mm_count: The number of references to &struct 682 * mm_struct (@mm_users count as 1). 683 * 684 * Use mmgrab()/mmdrop() to modify. When this drops to 685 * 0, the &struct mm_struct is freed. 686 */ 687 atomic_t mm_count; 688 } ____cacheline_aligned_in_smp; 689 690 struct maple_tree mm_mt; 691 #ifdef CONFIG_MMU 692 unsigned long (*get_unmapped_area) (struct file *filp, 693 unsigned long addr, unsigned long len, 694 unsigned long pgoff, unsigned long flags); 695 #endif 696 unsigned long mmap_base; /* base of mmap area */ 697 unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */ 698 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES 699 /* Base addresses for compatible mmap() */ 700 unsigned long mmap_compat_base; 701 unsigned long mmap_compat_legacy_base; 702 #endif 703 unsigned long task_size; /* size of task vm space */ 704 pgd_t * pgd; 705 706 #ifdef CONFIG_MEMBARRIER 707 /** 708 * @membarrier_state: Flags controlling membarrier behavior. 709 * 710 * This field is close to @pgd to hopefully fit in the same 711 * cache-line, which needs to be touched by switch_mm(). 712 */ 713 atomic_t membarrier_state; 714 #endif 715 716 /** 717 * @mm_users: The number of users including userspace. 718 * 719 * Use mmget()/mmget_not_zero()/mmput() to modify. When this 720 * drops to 0 (i.e. when the task exits and there are no other 721 * temporary reference holders), we also release a reference on 722 * @mm_count (which may then free the &struct mm_struct if 723 * @mm_count also drops to 0). 724 */ 725 atomic_t mm_users; 726 727 #ifdef CONFIG_SCHED_MM_CID 728 /** 729 * @pcpu_cid: Per-cpu current cid. 730 * 731 * Keep track of the currently allocated mm_cid for each cpu. 732 * The per-cpu mm_cid values are serialized by their respective 733 * runqueue locks. 734 */ 735 struct mm_cid __percpu *pcpu_cid; 736 /* 737 * @mm_cid_next_scan: Next mm_cid scan (in jiffies). 738 * 739 * When the next mm_cid scan is due (in jiffies). 740 */ 741 unsigned long mm_cid_next_scan; 742 #endif 743 #ifdef CONFIG_MMU 744 atomic_long_t pgtables_bytes; /* size of all page tables */ 745 #endif 746 int map_count; /* number of VMAs */ 747 748 spinlock_t page_table_lock; /* Protects page tables and some 749 * counters 750 */ 751 /* 752 * With some kernel config, the current mmap_lock's offset 753 * inside 'mm_struct' is at 0x120, which is very optimal, as 754 * its two hot fields 'count' and 'owner' sit in 2 different 755 * cachelines, and when mmap_lock is highly contended, both 756 * of the 2 fields will be accessed frequently, current layout 757 * will help to reduce cache bouncing. 758 * 759 * So please be careful with adding new fields before 760 * mmap_lock, which can easily push the 2 fields into one 761 * cacheline. 762 */ 763 struct rw_semaphore mmap_lock; 764 765 struct list_head mmlist; /* List of maybe swapped mm's. These 766 * are globally strung together off 767 * init_mm.mmlist, and are protected 768 * by mmlist_lock 769 */ 770 #ifdef CONFIG_PER_VMA_LOCK 771 /* 772 * This field has lock-like semantics, meaning it is sometimes 773 * accessed with ACQUIRE/RELEASE semantics. 774 * Roughly speaking, incrementing the sequence number is 775 * equivalent to releasing locks on VMAs; reading the sequence 776 * number can be part of taking a read lock on a VMA. 777 * 778 * Can be modified under write mmap_lock using RELEASE 779 * semantics. 780 * Can be read with no other protection when holding write 781 * mmap_lock. 782 * Can be read with ACQUIRE semantics if not holding write 783 * mmap_lock. 784 */ 785 int mm_lock_seq; 786 #endif 787 788 789 unsigned long hiwater_rss; /* High-watermark of RSS usage */ 790 unsigned long hiwater_vm; /* High-water virtual memory usage */ 791 792 unsigned long total_vm; /* Total pages mapped */ 793 unsigned long locked_vm; /* Pages that have PG_mlocked set */ 794 atomic64_t pinned_vm; /* Refcount permanently increased */ 795 unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */ 796 unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */ 797 unsigned long stack_vm; /* VM_STACK */ 798 unsigned long def_flags; 799 800 /** 801 * @write_protect_seq: Locked when any thread is write 802 * protecting pages mapped by this mm to enforce a later COW, 803 * for instance during page table copying for fork(). 804 */ 805 seqcount_t write_protect_seq; 806 807 spinlock_t arg_lock; /* protect the below fields */ 808 809 unsigned long start_code, end_code, start_data, end_data; 810 unsigned long start_brk, brk, start_stack; 811 unsigned long arg_start, arg_end, env_start, env_end; 812 813 unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */ 814 815 struct percpu_counter rss_stat[NR_MM_COUNTERS]; 816 817 struct linux_binfmt *binfmt; 818 819 /* Architecture-specific MM context */ 820 mm_context_t context; 821 822 unsigned long flags; /* Must use atomic bitops to access */ 823 824 #ifdef CONFIG_AIO 825 spinlock_t ioctx_lock; 826 struct kioctx_table __rcu *ioctx_table; 827 #endif 828 #ifdef CONFIG_MEMCG 829 /* 830 * "owner" points to a task that is regarded as the canonical 831 * user/owner of this mm. All of the following must be true in 832 * order for it to be changed: 833 * 834 * current == mm->owner 835 * current->mm != mm 836 * new_owner->mm == mm 837 * new_owner->alloc_lock is held 838 */ 839 struct task_struct __rcu *owner; 840 #endif 841 struct user_namespace *user_ns; 842 843 /* store ref to file /proc/<pid>/exe symlink points to */ 844 struct file __rcu *exe_file; 845 #ifdef CONFIG_MMU_NOTIFIER 846 struct mmu_notifier_subscriptions *notifier_subscriptions; 847 #endif 848 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 849 pgtable_t pmd_huge_pte; /* protected by page_table_lock */ 850 #endif 851 #ifdef CONFIG_NUMA_BALANCING 852 /* 853 * numa_next_scan is the next time that PTEs will be remapped 854 * PROT_NONE to trigger NUMA hinting faults; such faults gather 855 * statistics and migrate pages to new nodes if necessary. 856 */ 857 unsigned long numa_next_scan; 858 859 /* Restart point for scanning and remapping PTEs. */ 860 unsigned long numa_scan_offset; 861 862 /* numa_scan_seq prevents two threads remapping PTEs. */ 863 int numa_scan_seq; 864 #endif 865 /* 866 * An operation with batched TLB flushing is going on. Anything 867 * that can move process memory needs to flush the TLB when 868 * moving a PROT_NONE mapped page. 869 */ 870 atomic_t tlb_flush_pending; 871 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 872 /* See flush_tlb_batched_pending() */ 873 atomic_t tlb_flush_batched; 874 #endif 875 struct uprobes_state uprobes_state; 876 #ifdef CONFIG_PREEMPT_RT 877 struct rcu_head delayed_drop; 878 #endif 879 #ifdef CONFIG_HUGETLB_PAGE 880 atomic_long_t hugetlb_usage; 881 #endif 882 struct work_struct async_put_work; 883 884 #ifdef CONFIG_IOMMU_SVA 885 u32 pasid; 886 #endif 887 #ifdef CONFIG_KSM 888 /* 889 * Represent how many pages of this process are involved in KSM 890 * merging (not including ksm_zero_pages). 891 */ 892 unsigned long ksm_merging_pages; 893 /* 894 * Represent how many pages are checked for ksm merging 895 * including merged and not merged. 896 */ 897 unsigned long ksm_rmap_items; 898 /* 899 * Represent how many empty pages are merged with kernel zero 900 * pages when enabling KSM use_zero_pages. 901 */ 902 unsigned long ksm_zero_pages; 903 #endif /* CONFIG_KSM */ 904 #ifdef CONFIG_LRU_GEN 905 struct { 906 /* this mm_struct is on lru_gen_mm_list */ 907 struct list_head list; 908 /* 909 * Set when switching to this mm_struct, as a hint of 910 * whether it has been used since the last time per-node 911 * page table walkers cleared the corresponding bits. 912 */ 913 unsigned long bitmap; 914 #ifdef CONFIG_MEMCG 915 /* points to the memcg of "owner" above */ 916 struct mem_cgroup *memcg; 917 #endif 918 } lru_gen; 919 #endif /* CONFIG_LRU_GEN */ 920 } __randomize_layout; 921 922 /* 923 * The mm_cpumask needs to be at the end of mm_struct, because it 924 * is dynamically sized based on nr_cpu_ids. 925 */ 926 unsigned long cpu_bitmap[]; 927 }; 928 929 #define MM_MT_FLAGS (MT_FLAGS_ALLOC_RANGE | MT_FLAGS_LOCK_EXTERN | \ 930 MT_FLAGS_USE_RCU) 931 extern struct mm_struct init_mm; 932 933 /* Pointer magic because the dynamic array size confuses some compilers. */ 934 static inline void mm_init_cpumask(struct mm_struct *mm) 935 { 936 unsigned long cpu_bitmap = (unsigned long)mm; 937 938 cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap); 939 cpumask_clear((struct cpumask *)cpu_bitmap); 940 } 941 942 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ 943 static inline cpumask_t *mm_cpumask(struct mm_struct *mm) 944 { 945 return (struct cpumask *)&mm->cpu_bitmap; 946 } 947 948 #ifdef CONFIG_LRU_GEN 949 950 struct lru_gen_mm_list { 951 /* mm_struct list for page table walkers */ 952 struct list_head fifo; 953 /* protects the list above */ 954 spinlock_t lock; 955 }; 956 957 void lru_gen_add_mm(struct mm_struct *mm); 958 void lru_gen_del_mm(struct mm_struct *mm); 959 #ifdef CONFIG_MEMCG 960 void lru_gen_migrate_mm(struct mm_struct *mm); 961 #endif 962 963 static inline void lru_gen_init_mm(struct mm_struct *mm) 964 { 965 INIT_LIST_HEAD(&mm->lru_gen.list); 966 mm->lru_gen.bitmap = 0; 967 #ifdef CONFIG_MEMCG 968 mm->lru_gen.memcg = NULL; 969 #endif 970 } 971 972 static inline void lru_gen_use_mm(struct mm_struct *mm) 973 { 974 /* 975 * When the bitmap is set, page reclaim knows this mm_struct has been 976 * used since the last time it cleared the bitmap. So it might be worth 977 * walking the page tables of this mm_struct to clear the accessed bit. 978 */ 979 WRITE_ONCE(mm->lru_gen.bitmap, -1); 980 } 981 982 #else /* !CONFIG_LRU_GEN */ 983 984 static inline void lru_gen_add_mm(struct mm_struct *mm) 985 { 986 } 987 988 static inline void lru_gen_del_mm(struct mm_struct *mm) 989 { 990 } 991 992 #ifdef CONFIG_MEMCG 993 static inline void lru_gen_migrate_mm(struct mm_struct *mm) 994 { 995 } 996 #endif 997 998 static inline void lru_gen_init_mm(struct mm_struct *mm) 999 { 1000 } 1001 1002 static inline void lru_gen_use_mm(struct mm_struct *mm) 1003 { 1004 } 1005 1006 #endif /* CONFIG_LRU_GEN */ 1007 1008 struct vma_iterator { 1009 struct ma_state mas; 1010 }; 1011 1012 #define VMA_ITERATOR(name, __mm, __addr) \ 1013 struct vma_iterator name = { \ 1014 .mas = { \ 1015 .tree = &(__mm)->mm_mt, \ 1016 .index = __addr, \ 1017 .node = MAS_START, \ 1018 }, \ 1019 } 1020 1021 static inline void vma_iter_init(struct vma_iterator *vmi, 1022 struct mm_struct *mm, unsigned long addr) 1023 { 1024 mas_init(&vmi->mas, &mm->mm_mt, addr); 1025 } 1026 1027 #ifdef CONFIG_SCHED_MM_CID 1028 1029 enum mm_cid_state { 1030 MM_CID_UNSET = -1U, /* Unset state has lazy_put flag set. */ 1031 MM_CID_LAZY_PUT = (1U << 31), 1032 }; 1033 1034 static inline bool mm_cid_is_unset(int cid) 1035 { 1036 return cid == MM_CID_UNSET; 1037 } 1038 1039 static inline bool mm_cid_is_lazy_put(int cid) 1040 { 1041 return !mm_cid_is_unset(cid) && (cid & MM_CID_LAZY_PUT); 1042 } 1043 1044 static inline bool mm_cid_is_valid(int cid) 1045 { 1046 return !(cid & MM_CID_LAZY_PUT); 1047 } 1048 1049 static inline int mm_cid_set_lazy_put(int cid) 1050 { 1051 return cid | MM_CID_LAZY_PUT; 1052 } 1053 1054 static inline int mm_cid_clear_lazy_put(int cid) 1055 { 1056 return cid & ~MM_CID_LAZY_PUT; 1057 } 1058 1059 /* Accessor for struct mm_struct's cidmask. */ 1060 static inline cpumask_t *mm_cidmask(struct mm_struct *mm) 1061 { 1062 unsigned long cid_bitmap = (unsigned long)mm; 1063 1064 cid_bitmap += offsetof(struct mm_struct, cpu_bitmap); 1065 /* Skip cpu_bitmap */ 1066 cid_bitmap += cpumask_size(); 1067 return (struct cpumask *)cid_bitmap; 1068 } 1069 1070 static inline void mm_init_cid(struct mm_struct *mm) 1071 { 1072 int i; 1073 1074 for_each_possible_cpu(i) { 1075 struct mm_cid *pcpu_cid = per_cpu_ptr(mm->pcpu_cid, i); 1076 1077 pcpu_cid->cid = MM_CID_UNSET; 1078 pcpu_cid->time = 0; 1079 } 1080 cpumask_clear(mm_cidmask(mm)); 1081 } 1082 1083 static inline int mm_alloc_cid(struct mm_struct *mm) 1084 { 1085 mm->pcpu_cid = alloc_percpu(struct mm_cid); 1086 if (!mm->pcpu_cid) 1087 return -ENOMEM; 1088 mm_init_cid(mm); 1089 return 0; 1090 } 1091 1092 static inline void mm_destroy_cid(struct mm_struct *mm) 1093 { 1094 free_percpu(mm->pcpu_cid); 1095 mm->pcpu_cid = NULL; 1096 } 1097 1098 static inline unsigned int mm_cid_size(void) 1099 { 1100 return cpumask_size(); 1101 } 1102 #else /* CONFIG_SCHED_MM_CID */ 1103 static inline void mm_init_cid(struct mm_struct *mm) { } 1104 static inline int mm_alloc_cid(struct mm_struct *mm) { return 0; } 1105 static inline void mm_destroy_cid(struct mm_struct *mm) { } 1106 static inline unsigned int mm_cid_size(void) 1107 { 1108 return 0; 1109 } 1110 #endif /* CONFIG_SCHED_MM_CID */ 1111 1112 struct mmu_gather; 1113 extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm); 1114 extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm); 1115 extern void tlb_finish_mmu(struct mmu_gather *tlb); 1116 1117 struct vm_fault; 1118 1119 /** 1120 * typedef vm_fault_t - Return type for page fault handlers. 1121 * 1122 * Page fault handlers return a bitmask of %VM_FAULT values. 1123 */ 1124 typedef __bitwise unsigned int vm_fault_t; 1125 1126 /** 1127 * enum vm_fault_reason - Page fault handlers return a bitmask of 1128 * these values to tell the core VM what happened when handling the 1129 * fault. Used to decide whether a process gets delivered SIGBUS or 1130 * just gets major/minor fault counters bumped up. 1131 * 1132 * @VM_FAULT_OOM: Out Of Memory 1133 * @VM_FAULT_SIGBUS: Bad access 1134 * @VM_FAULT_MAJOR: Page read from storage 1135 * @VM_FAULT_HWPOISON: Hit poisoned small page 1136 * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded 1137 * in upper bits 1138 * @VM_FAULT_SIGSEGV: segmentation fault 1139 * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page 1140 * @VM_FAULT_LOCKED: ->fault locked the returned page 1141 * @VM_FAULT_RETRY: ->fault blocked, must retry 1142 * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small 1143 * @VM_FAULT_DONE_COW: ->fault has fully handled COW 1144 * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs 1145 * fsync() to complete (for synchronous page faults 1146 * in DAX) 1147 * @VM_FAULT_COMPLETED: ->fault completed, meanwhile mmap lock released 1148 * @VM_FAULT_HINDEX_MASK: mask HINDEX value 1149 * 1150 */ 1151 enum vm_fault_reason { 1152 VM_FAULT_OOM = (__force vm_fault_t)0x000001, 1153 VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002, 1154 VM_FAULT_MAJOR = (__force vm_fault_t)0x000004, 1155 VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010, 1156 VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020, 1157 VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040, 1158 VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100, 1159 VM_FAULT_LOCKED = (__force vm_fault_t)0x000200, 1160 VM_FAULT_RETRY = (__force vm_fault_t)0x000400, 1161 VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800, 1162 VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000, 1163 VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000, 1164 VM_FAULT_COMPLETED = (__force vm_fault_t)0x004000, 1165 VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000, 1166 }; 1167 1168 /* Encode hstate index for a hwpoisoned large page */ 1169 #define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16)) 1170 #define VM_FAULT_GET_HINDEX(x) (((__force unsigned int)(x) >> 16) & 0xf) 1171 1172 #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \ 1173 VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \ 1174 VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK) 1175 1176 #define VM_FAULT_RESULT_TRACE \ 1177 { VM_FAULT_OOM, "OOM" }, \ 1178 { VM_FAULT_SIGBUS, "SIGBUS" }, \ 1179 { VM_FAULT_MAJOR, "MAJOR" }, \ 1180 { VM_FAULT_HWPOISON, "HWPOISON" }, \ 1181 { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \ 1182 { VM_FAULT_SIGSEGV, "SIGSEGV" }, \ 1183 { VM_FAULT_NOPAGE, "NOPAGE" }, \ 1184 { VM_FAULT_LOCKED, "LOCKED" }, \ 1185 { VM_FAULT_RETRY, "RETRY" }, \ 1186 { VM_FAULT_FALLBACK, "FALLBACK" }, \ 1187 { VM_FAULT_DONE_COW, "DONE_COW" }, \ 1188 { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \ 1189 { VM_FAULT_COMPLETED, "COMPLETED" } 1190 1191 struct vm_special_mapping { 1192 const char *name; /* The name, e.g. "[vdso]". */ 1193 1194 /* 1195 * If .fault is not provided, this points to a 1196 * NULL-terminated array of pages that back the special mapping. 1197 * 1198 * This must not be NULL unless .fault is provided. 1199 */ 1200 struct page **pages; 1201 1202 /* 1203 * If non-NULL, then this is called to resolve page faults 1204 * on the special mapping. If used, .pages is not checked. 1205 */ 1206 vm_fault_t (*fault)(const struct vm_special_mapping *sm, 1207 struct vm_area_struct *vma, 1208 struct vm_fault *vmf); 1209 1210 int (*mremap)(const struct vm_special_mapping *sm, 1211 struct vm_area_struct *new_vma); 1212 }; 1213 1214 enum tlb_flush_reason { 1215 TLB_FLUSH_ON_TASK_SWITCH, 1216 TLB_REMOTE_SHOOTDOWN, 1217 TLB_LOCAL_SHOOTDOWN, 1218 TLB_LOCAL_MM_SHOOTDOWN, 1219 TLB_REMOTE_SEND_IPI, 1220 NR_TLB_FLUSH_REASONS, 1221 }; 1222 1223 /** 1224 * enum fault_flag - Fault flag definitions. 1225 * @FAULT_FLAG_WRITE: Fault was a write fault. 1226 * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE. 1227 * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked. 1228 * @FAULT_FLAG_RETRY_NOWAIT: Don't drop mmap_lock and wait when retrying. 1229 * @FAULT_FLAG_KILLABLE: The fault task is in SIGKILL killable region. 1230 * @FAULT_FLAG_TRIED: The fault has been tried once. 1231 * @FAULT_FLAG_USER: The fault originated in userspace. 1232 * @FAULT_FLAG_REMOTE: The fault is not for current task/mm. 1233 * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch. 1234 * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals. 1235 * @FAULT_FLAG_UNSHARE: The fault is an unsharing request to break COW in a 1236 * COW mapping, making sure that an exclusive anon page is 1237 * mapped after the fault. 1238 * @FAULT_FLAG_ORIG_PTE_VALID: whether the fault has vmf->orig_pte cached. 1239 * We should only access orig_pte if this flag set. 1240 * @FAULT_FLAG_VMA_LOCK: The fault is handled under VMA lock. 1241 * 1242 * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify 1243 * whether we would allow page faults to retry by specifying these two 1244 * fault flags correctly. Currently there can be three legal combinations: 1245 * 1246 * (a) ALLOW_RETRY and !TRIED: this means the page fault allows retry, and 1247 * this is the first try 1248 * 1249 * (b) ALLOW_RETRY and TRIED: this means the page fault allows retry, and 1250 * we've already tried at least once 1251 * 1252 * (c) !ALLOW_RETRY and !TRIED: this means the page fault does not allow retry 1253 * 1254 * The unlisted combination (!ALLOW_RETRY && TRIED) is illegal and should never 1255 * be used. Note that page faults can be allowed to retry for multiple times, 1256 * in which case we'll have an initial fault with flags (a) then later on 1257 * continuous faults with flags (b). We should always try to detect pending 1258 * signals before a retry to make sure the continuous page faults can still be 1259 * interrupted if necessary. 1260 * 1261 * The combination FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE is illegal. 1262 * FAULT_FLAG_UNSHARE is ignored and treated like an ordinary read fault when 1263 * applied to mappings that are not COW mappings. 1264 */ 1265 enum fault_flag { 1266 FAULT_FLAG_WRITE = 1 << 0, 1267 FAULT_FLAG_MKWRITE = 1 << 1, 1268 FAULT_FLAG_ALLOW_RETRY = 1 << 2, 1269 FAULT_FLAG_RETRY_NOWAIT = 1 << 3, 1270 FAULT_FLAG_KILLABLE = 1 << 4, 1271 FAULT_FLAG_TRIED = 1 << 5, 1272 FAULT_FLAG_USER = 1 << 6, 1273 FAULT_FLAG_REMOTE = 1 << 7, 1274 FAULT_FLAG_INSTRUCTION = 1 << 8, 1275 FAULT_FLAG_INTERRUPTIBLE = 1 << 9, 1276 FAULT_FLAG_UNSHARE = 1 << 10, 1277 FAULT_FLAG_ORIG_PTE_VALID = 1 << 11, 1278 FAULT_FLAG_VMA_LOCK = 1 << 12, 1279 }; 1280 1281 typedef unsigned int __bitwise zap_flags_t; 1282 1283 /* 1284 * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each 1285 * other. Here is what they mean, and how to use them: 1286 * 1287 * 1288 * FIXME: For pages which are part of a filesystem, mappings are subject to the 1289 * lifetime enforced by the filesystem and we need guarantees that longterm 1290 * users like RDMA and V4L2 only establish mappings which coordinate usage with 1291 * the filesystem. Ideas for this coordination include revoking the longterm 1292 * pin, delaying writeback, bounce buffer page writeback, etc. As FS DAX was 1293 * added after the problem with filesystems was found FS DAX VMAs are 1294 * specifically failed. Filesystem pages are still subject to bugs and use of 1295 * FOLL_LONGTERM should be avoided on those pages. 1296 * 1297 * In the CMA case: long term pins in a CMA region would unnecessarily fragment 1298 * that region. And so, CMA attempts to migrate the page before pinning, when 1299 * FOLL_LONGTERM is specified. 1300 * 1301 * FOLL_PIN indicates that a special kind of tracking (not just page->_refcount, 1302 * but an additional pin counting system) will be invoked. This is intended for 1303 * anything that gets a page reference and then touches page data (for example, 1304 * Direct IO). This lets the filesystem know that some non-file-system entity is 1305 * potentially changing the pages' data. In contrast to FOLL_GET (whose pages 1306 * are released via put_page()), FOLL_PIN pages must be released, ultimately, by 1307 * a call to unpin_user_page(). 1308 * 1309 * FOLL_PIN is similar to FOLL_GET: both of these pin pages. They use different 1310 * and separate refcounting mechanisms, however, and that means that each has 1311 * its own acquire and release mechanisms: 1312 * 1313 * FOLL_GET: get_user_pages*() to acquire, and put_page() to release. 1314 * 1315 * FOLL_PIN: pin_user_pages*() to acquire, and unpin_user_pages to release. 1316 * 1317 * FOLL_PIN and FOLL_GET are mutually exclusive for a given function call. 1318 * (The underlying pages may experience both FOLL_GET-based and FOLL_PIN-based 1319 * calls applied to them, and that's perfectly OK. This is a constraint on the 1320 * callers, not on the pages.) 1321 * 1322 * FOLL_PIN should be set internally by the pin_user_pages*() APIs, never 1323 * directly by the caller. That's in order to help avoid mismatches when 1324 * releasing pages: get_user_pages*() pages must be released via put_page(), 1325 * while pin_user_pages*() pages must be released via unpin_user_page(). 1326 * 1327 * Please see Documentation/core-api/pin_user_pages.rst for more information. 1328 */ 1329 1330 enum { 1331 /* check pte is writable */ 1332 FOLL_WRITE = 1 << 0, 1333 /* do get_page on page */ 1334 FOLL_GET = 1 << 1, 1335 /* give error on hole if it would be zero */ 1336 FOLL_DUMP = 1 << 2, 1337 /* get_user_pages read/write w/o permission */ 1338 FOLL_FORCE = 1 << 3, 1339 /* 1340 * if a disk transfer is needed, start the IO and return without waiting 1341 * upon it 1342 */ 1343 FOLL_NOWAIT = 1 << 4, 1344 /* do not fault in pages */ 1345 FOLL_NOFAULT = 1 << 5, 1346 /* check page is hwpoisoned */ 1347 FOLL_HWPOISON = 1 << 6, 1348 /* don't do file mappings */ 1349 FOLL_ANON = 1 << 7, 1350 /* 1351 * FOLL_LONGTERM indicates that the page will be held for an indefinite 1352 * time period _often_ under userspace control. This is in contrast to 1353 * iov_iter_get_pages(), whose usages are transient. 1354 */ 1355 FOLL_LONGTERM = 1 << 8, 1356 /* split huge pmd before returning */ 1357 FOLL_SPLIT_PMD = 1 << 9, 1358 /* allow returning PCI P2PDMA pages */ 1359 FOLL_PCI_P2PDMA = 1 << 10, 1360 /* allow interrupts from generic signals */ 1361 FOLL_INTERRUPTIBLE = 1 << 11, 1362 /* 1363 * Always honor (trigger) NUMA hinting faults. 1364 * 1365 * FOLL_WRITE implicitly honors NUMA hinting faults because a 1366 * PROT_NONE-mapped page is not writable (exceptions with FOLL_FORCE 1367 * apply). get_user_pages_fast_only() always implicitly honors NUMA 1368 * hinting faults. 1369 */ 1370 FOLL_HONOR_NUMA_FAULT = 1 << 12, 1371 1372 /* See also internal only FOLL flags in mm/internal.h */ 1373 }; 1374 1375 #endif /* _LINUX_MM_TYPES_H */ 1376