1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Macros for manipulating and testing page->flags 4 */ 5 6 #ifndef PAGE_FLAGS_H 7 #define PAGE_FLAGS_H 8 9 #include <linux/types.h> 10 #include <linux/bug.h> 11 #include <linux/mmdebug.h> 12 #ifndef __GENERATING_BOUNDS_H 13 #include <linux/mm_types.h> 14 #include <generated/bounds.h> 15 #endif /* !__GENERATING_BOUNDS_H */ 16 17 /* 18 * Various page->flags bits: 19 * 20 * PG_reserved is set for special pages, which can never be swapped out. Some 21 * of them might not even exist... 22 * 23 * The PG_private bitflag is set on pagecache pages if they contain filesystem 24 * specific data (which is normally at page->private). It can be used by 25 * private allocations for its own usage. 26 * 27 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O 28 * and cleared when writeback _starts_ or when read _completes_. PG_writeback 29 * is set before writeback starts and cleared when it finishes. 30 * 31 * PG_locked also pins a page in pagecache, and blocks truncation of the file 32 * while it is held. 33 * 34 * page_waitqueue(page) is a wait queue of all tasks waiting for the page 35 * to become unlocked. 36 * 37 * PG_uptodate tells whether the page's contents is valid. When a read 38 * completes, the page becomes uptodate, unless a disk I/O error happened. 39 * 40 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and 41 * file-backed pagecache (see mm/vmscan.c). 42 * 43 * PG_error is set to indicate that an I/O error occurred on this page. 44 * 45 * PG_arch_1 is an architecture specific page state bit. The generic code 46 * guarantees that this bit is cleared for a page when it first is entered into 47 * the page cache. 48 * 49 * PG_hwpoison indicates that a page got corrupted in hardware and contains 50 * data with incorrect ECC bits that triggered a machine check. Accessing is 51 * not safe since it may cause another machine check. Don't touch! 52 */ 53 54 /* 55 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break 56 * locked- and dirty-page accounting. 57 * 58 * The page flags field is split into two parts, the main flags area 59 * which extends from the low bits upwards, and the fields area which 60 * extends from the high bits downwards. 61 * 62 * | FIELD | ... | FLAGS | 63 * N-1 ^ 0 64 * (NR_PAGEFLAGS) 65 * 66 * The fields area is reserved for fields mapping zone, node (for NUMA) and 67 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like 68 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). 69 */ 70 enum pageflags { 71 PG_locked, /* Page is locked. Don't touch. */ 72 PG_referenced, 73 PG_uptodate, 74 PG_dirty, 75 PG_lru, 76 PG_active, 77 PG_workingset, 78 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */ 79 PG_error, 80 PG_slab, 81 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ 82 PG_arch_1, 83 PG_reserved, 84 PG_private, /* If pagecache, has fs-private data */ 85 PG_private_2, /* If pagecache, has fs aux data */ 86 PG_writeback, /* Page is under writeback */ 87 PG_head, /* A head page */ 88 PG_mappedtodisk, /* Has blocks allocated on-disk */ 89 PG_reclaim, /* To be reclaimed asap */ 90 PG_swapbacked, /* Page is backed by RAM/swap */ 91 PG_unevictable, /* Page is "unevictable" */ 92 #ifdef CONFIG_MMU 93 PG_mlocked, /* Page is vma mlocked */ 94 #endif 95 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 96 PG_uncached, /* Page has been mapped as uncached */ 97 #endif 98 #ifdef CONFIG_MEMORY_FAILURE 99 PG_hwpoison, /* hardware poisoned page. Don't touch */ 100 #endif 101 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 102 PG_young, 103 PG_idle, 104 #endif 105 __NR_PAGEFLAGS, 106 107 /* Filesystems */ 108 PG_checked = PG_owner_priv_1, 109 110 /* SwapBacked */ 111 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ 112 113 /* Two page bits are conscripted by FS-Cache to maintain local caching 114 * state. These bits are set on pages belonging to the netfs's inodes 115 * when those inodes are being locally cached. 116 */ 117 PG_fscache = PG_private_2, /* page backed by cache */ 118 119 /* XEN */ 120 /* Pinned in Xen as a read-only pagetable page. */ 121 PG_pinned = PG_owner_priv_1, 122 /* Pinned as part of domain save (see xen_mm_pin_all()). */ 123 PG_savepinned = PG_dirty, 124 /* Has a grant mapping of another (foreign) domain's page. */ 125 PG_foreign = PG_owner_priv_1, 126 127 /* SLOB */ 128 PG_slob_free = PG_private, 129 130 /* Compound pages. Stored in first tail page's flags */ 131 PG_double_map = PG_private_2, 132 133 /* non-lru isolated movable page */ 134 PG_isolated = PG_reclaim, 135 }; 136 137 #ifndef __GENERATING_BOUNDS_H 138 139 struct page; /* forward declaration */ 140 141 static inline struct page *compound_head(struct page *page) 142 { 143 unsigned long head = READ_ONCE(page->compound_head); 144 145 if (unlikely(head & 1)) 146 return (struct page *) (head - 1); 147 return page; 148 } 149 150 static __always_inline int PageTail(struct page *page) 151 { 152 return READ_ONCE(page->compound_head) & 1; 153 } 154 155 static __always_inline int PageCompound(struct page *page) 156 { 157 return test_bit(PG_head, &page->flags) || PageTail(page); 158 } 159 160 #define PAGE_POISON_PATTERN -1l 161 static inline int PagePoisoned(const struct page *page) 162 { 163 return page->flags == PAGE_POISON_PATTERN; 164 } 165 166 #ifdef CONFIG_DEBUG_VM 167 void page_init_poison(struct page *page, size_t size); 168 #else 169 static inline void page_init_poison(struct page *page, size_t size) 170 { 171 } 172 #endif 173 174 /* 175 * Page flags policies wrt compound pages 176 * 177 * PF_POISONED_CHECK 178 * check if this struct page poisoned/uninitialized 179 * 180 * PF_ANY: 181 * the page flag is relevant for small, head and tail pages. 182 * 183 * PF_HEAD: 184 * for compound page all operations related to the page flag applied to 185 * head page. 186 * 187 * PF_ONLY_HEAD: 188 * for compound page, callers only ever operate on the head page. 189 * 190 * PF_NO_TAIL: 191 * modifications of the page flag must be done on small or head pages, 192 * checks can be done on tail pages too. 193 * 194 * PF_NO_COMPOUND: 195 * the page flag is not relevant for compound pages. 196 */ 197 #define PF_POISONED_CHECK(page) ({ \ 198 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \ 199 page; }) 200 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page) 201 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page)) 202 #define PF_ONLY_HEAD(page, enforce) ({ \ 203 VM_BUG_ON_PGFLAGS(PageTail(page), page); \ 204 PF_POISONED_CHECK(page); }) 205 #define PF_NO_TAIL(page, enforce) ({ \ 206 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ 207 PF_POISONED_CHECK(compound_head(page)); }) 208 #define PF_NO_COMPOUND(page, enforce) ({ \ 209 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \ 210 PF_POISONED_CHECK(page); }) 211 212 /* 213 * Macros to create function definitions for page flags 214 */ 215 #define TESTPAGEFLAG(uname, lname, policy) \ 216 static __always_inline int Page##uname(struct page *page) \ 217 { return test_bit(PG_##lname, &policy(page, 0)->flags); } 218 219 #define SETPAGEFLAG(uname, lname, policy) \ 220 static __always_inline void SetPage##uname(struct page *page) \ 221 { set_bit(PG_##lname, &policy(page, 1)->flags); } 222 223 #define CLEARPAGEFLAG(uname, lname, policy) \ 224 static __always_inline void ClearPage##uname(struct page *page) \ 225 { clear_bit(PG_##lname, &policy(page, 1)->flags); } 226 227 #define __SETPAGEFLAG(uname, lname, policy) \ 228 static __always_inline void __SetPage##uname(struct page *page) \ 229 { __set_bit(PG_##lname, &policy(page, 1)->flags); } 230 231 #define __CLEARPAGEFLAG(uname, lname, policy) \ 232 static __always_inline void __ClearPage##uname(struct page *page) \ 233 { __clear_bit(PG_##lname, &policy(page, 1)->flags); } 234 235 #define TESTSETFLAG(uname, lname, policy) \ 236 static __always_inline int TestSetPage##uname(struct page *page) \ 237 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); } 238 239 #define TESTCLEARFLAG(uname, lname, policy) \ 240 static __always_inline int TestClearPage##uname(struct page *page) \ 241 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); } 242 243 #define PAGEFLAG(uname, lname, policy) \ 244 TESTPAGEFLAG(uname, lname, policy) \ 245 SETPAGEFLAG(uname, lname, policy) \ 246 CLEARPAGEFLAG(uname, lname, policy) 247 248 #define __PAGEFLAG(uname, lname, policy) \ 249 TESTPAGEFLAG(uname, lname, policy) \ 250 __SETPAGEFLAG(uname, lname, policy) \ 251 __CLEARPAGEFLAG(uname, lname, policy) 252 253 #define TESTSCFLAG(uname, lname, policy) \ 254 TESTSETFLAG(uname, lname, policy) \ 255 TESTCLEARFLAG(uname, lname, policy) 256 257 #define TESTPAGEFLAG_FALSE(uname) \ 258 static inline int Page##uname(const struct page *page) { return 0; } 259 260 #define SETPAGEFLAG_NOOP(uname) \ 261 static inline void SetPage##uname(struct page *page) { } 262 263 #define CLEARPAGEFLAG_NOOP(uname) \ 264 static inline void ClearPage##uname(struct page *page) { } 265 266 #define __CLEARPAGEFLAG_NOOP(uname) \ 267 static inline void __ClearPage##uname(struct page *page) { } 268 269 #define TESTSETFLAG_FALSE(uname) \ 270 static inline int TestSetPage##uname(struct page *page) { return 0; } 271 272 #define TESTCLEARFLAG_FALSE(uname) \ 273 static inline int TestClearPage##uname(struct page *page) { return 0; } 274 275 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \ 276 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname) 277 278 #define TESTSCFLAG_FALSE(uname) \ 279 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname) 280 281 __PAGEFLAG(Locked, locked, PF_NO_TAIL) 282 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) 283 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND) 284 PAGEFLAG(Referenced, referenced, PF_HEAD) 285 TESTCLEARFLAG(Referenced, referenced, PF_HEAD) 286 __SETPAGEFLAG(Referenced, referenced, PF_HEAD) 287 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD) 288 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD) 289 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD) 290 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) 291 TESTCLEARFLAG(Active, active, PF_HEAD) 292 PAGEFLAG(Workingset, workingset, PF_HEAD) 293 TESTCLEARFLAG(Workingset, workingset, PF_HEAD) 294 __PAGEFLAG(Slab, slab, PF_NO_TAIL) 295 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL) 296 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */ 297 298 /* Xen */ 299 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND) 300 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND) 301 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND); 302 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND); 303 304 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 305 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 306 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 307 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 308 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 309 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 310 311 /* 312 * Private page markings that may be used by the filesystem that owns the page 313 * for its own purposes. 314 * - PG_private and PG_private_2 cause releasepage() and co to be invoked 315 */ 316 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY) 317 __CLEARPAGEFLAG(Private, private, PF_ANY) 318 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY) 319 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 320 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 321 322 /* 323 * Only test-and-set exist for PG_writeback. The unconditional operators are 324 * risky: they bypass page accounting. 325 */ 326 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL) 327 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL) 328 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL) 329 330 /* PG_readahead is only used for reads; PG_reclaim is only for writes */ 331 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) 332 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) 333 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) 334 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND) 335 336 #ifdef CONFIG_HIGHMEM 337 /* 338 * Must use a macro here due to header dependency issues. page_zone() is not 339 * available at this point. 340 */ 341 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) 342 #else 343 PAGEFLAG_FALSE(HighMem) 344 #endif 345 346 #ifdef CONFIG_SWAP 347 static __always_inline int PageSwapCache(struct page *page) 348 { 349 #ifdef CONFIG_THP_SWAP 350 page = compound_head(page); 351 #endif 352 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); 353 354 } 355 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 356 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 357 #else 358 PAGEFLAG_FALSE(SwapCache) 359 #endif 360 361 PAGEFLAG(Unevictable, unevictable, PF_HEAD) 362 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD) 363 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD) 364 365 #ifdef CONFIG_MMU 366 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 367 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 368 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL) 369 #else 370 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked) 371 TESTSCFLAG_FALSE(Mlocked) 372 #endif 373 374 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 375 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND) 376 #else 377 PAGEFLAG_FALSE(Uncached) 378 #endif 379 380 #ifdef CONFIG_MEMORY_FAILURE 381 PAGEFLAG(HWPoison, hwpoison, PF_ANY) 382 TESTSCFLAG(HWPoison, hwpoison, PF_ANY) 383 #define __PG_HWPOISON (1UL << PG_hwpoison) 384 extern bool set_hwpoison_free_buddy_page(struct page *page); 385 #else 386 PAGEFLAG_FALSE(HWPoison) 387 static inline bool set_hwpoison_free_buddy_page(struct page *page) 388 { 389 return 0; 390 } 391 #define __PG_HWPOISON 0 392 #endif 393 394 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 395 TESTPAGEFLAG(Young, young, PF_ANY) 396 SETPAGEFLAG(Young, young, PF_ANY) 397 TESTCLEARFLAG(Young, young, PF_ANY) 398 PAGEFLAG(Idle, idle, PF_ANY) 399 #endif 400 401 /* 402 * On an anonymous page mapped into a user virtual memory area, 403 * page->mapping points to its anon_vma, not to a struct address_space; 404 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h. 405 * 406 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled, 407 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON 408 * bit; and then page->mapping points, not to an anon_vma, but to a private 409 * structure which KSM associates with that merged page. See ksm.h. 410 * 411 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable 412 * page and then page->mapping points a struct address_space. 413 * 414 * Please note that, confusingly, "page_mapping" refers to the inode 415 * address_space which maps the page from disk; whereas "page_mapped" 416 * refers to user virtual address space into which the page is mapped. 417 */ 418 #define PAGE_MAPPING_ANON 0x1 419 #define PAGE_MAPPING_MOVABLE 0x2 420 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 421 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 422 423 static __always_inline int PageMappingFlags(struct page *page) 424 { 425 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0; 426 } 427 428 static __always_inline int PageAnon(struct page *page) 429 { 430 page = compound_head(page); 431 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0; 432 } 433 434 static __always_inline int __PageMovable(struct page *page) 435 { 436 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 437 PAGE_MAPPING_MOVABLE; 438 } 439 440 #ifdef CONFIG_KSM 441 /* 442 * A KSM page is one of those write-protected "shared pages" or "merged pages" 443 * which KSM maps into multiple mms, wherever identical anonymous page content 444 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any 445 * anon_vma, but to that page's node of the stable tree. 446 */ 447 static __always_inline int PageKsm(struct page *page) 448 { 449 page = compound_head(page); 450 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 451 PAGE_MAPPING_KSM; 452 } 453 #else 454 TESTPAGEFLAG_FALSE(Ksm) 455 #endif 456 457 u64 stable_page_flags(struct page *page); 458 459 static inline int PageUptodate(struct page *page) 460 { 461 int ret; 462 page = compound_head(page); 463 ret = test_bit(PG_uptodate, &(page)->flags); 464 /* 465 * Must ensure that the data we read out of the page is loaded 466 * _after_ we've loaded page->flags to check for PageUptodate. 467 * We can skip the barrier if the page is not uptodate, because 468 * we wouldn't be reading anything from it. 469 * 470 * See SetPageUptodate() for the other side of the story. 471 */ 472 if (ret) 473 smp_rmb(); 474 475 return ret; 476 } 477 478 static __always_inline void __SetPageUptodate(struct page *page) 479 { 480 VM_BUG_ON_PAGE(PageTail(page), page); 481 smp_wmb(); 482 __set_bit(PG_uptodate, &page->flags); 483 } 484 485 static __always_inline void SetPageUptodate(struct page *page) 486 { 487 VM_BUG_ON_PAGE(PageTail(page), page); 488 /* 489 * Memory barrier must be issued before setting the PG_uptodate bit, 490 * so that all previous stores issued in order to bring the page 491 * uptodate are actually visible before PageUptodate becomes true. 492 */ 493 smp_wmb(); 494 set_bit(PG_uptodate, &page->flags); 495 } 496 497 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL) 498 499 int test_clear_page_writeback(struct page *page); 500 int __test_set_page_writeback(struct page *page, bool keep_write); 501 502 #define test_set_page_writeback(page) \ 503 __test_set_page_writeback(page, false) 504 #define test_set_page_writeback_keepwrite(page) \ 505 __test_set_page_writeback(page, true) 506 507 static inline void set_page_writeback(struct page *page) 508 { 509 test_set_page_writeback(page); 510 } 511 512 static inline void set_page_writeback_keepwrite(struct page *page) 513 { 514 test_set_page_writeback_keepwrite(page); 515 } 516 517 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY) 518 519 static __always_inline void set_compound_head(struct page *page, struct page *head) 520 { 521 WRITE_ONCE(page->compound_head, (unsigned long)head + 1); 522 } 523 524 static __always_inline void clear_compound_head(struct page *page) 525 { 526 WRITE_ONCE(page->compound_head, 0); 527 } 528 529 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 530 static inline void ClearPageCompound(struct page *page) 531 { 532 BUG_ON(!PageHead(page)); 533 ClearPageHead(page); 534 } 535 #endif 536 537 #define PG_head_mask ((1UL << PG_head)) 538 539 #ifdef CONFIG_HUGETLB_PAGE 540 int PageHuge(struct page *page); 541 int PageHeadHuge(struct page *page); 542 bool page_huge_active(struct page *page); 543 #else 544 TESTPAGEFLAG_FALSE(Huge) 545 TESTPAGEFLAG_FALSE(HeadHuge) 546 547 static inline bool page_huge_active(struct page *page) 548 { 549 return 0; 550 } 551 #endif 552 553 554 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 555 /* 556 * PageHuge() only returns true for hugetlbfs pages, but not for 557 * normal or transparent huge pages. 558 * 559 * PageTransHuge() returns true for both transparent huge and 560 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be 561 * called only in the core VM paths where hugetlbfs pages can't exist. 562 */ 563 static inline int PageTransHuge(struct page *page) 564 { 565 VM_BUG_ON_PAGE(PageTail(page), page); 566 return PageHead(page); 567 } 568 569 /* 570 * PageTransCompound returns true for both transparent huge pages 571 * and hugetlbfs pages, so it should only be called when it's known 572 * that hugetlbfs pages aren't involved. 573 */ 574 static inline int PageTransCompound(struct page *page) 575 { 576 return PageCompound(page); 577 } 578 579 /* 580 * PageTransCompoundMap is the same as PageTransCompound, but it also 581 * guarantees the primary MMU has the entire compound page mapped 582 * through pmd_trans_huge, which in turn guarantees the secondary MMUs 583 * can also map the entire compound page. This allows the secondary 584 * MMUs to call get_user_pages() only once for each compound page and 585 * to immediately map the entire compound page with a single secondary 586 * MMU fault. If there will be a pmd split later, the secondary MMUs 587 * will get an update through the MMU notifier invalidation through 588 * split_huge_pmd(). 589 * 590 * Unlike PageTransCompound, this is safe to be called only while 591 * split_huge_pmd() cannot run from under us, like if protected by the 592 * MMU notifier, otherwise it may result in page->_mapcount < 0 false 593 * positives. 594 */ 595 static inline int PageTransCompoundMap(struct page *page) 596 { 597 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0; 598 } 599 600 /* 601 * PageTransTail returns true for both transparent huge pages 602 * and hugetlbfs pages, so it should only be called when it's known 603 * that hugetlbfs pages aren't involved. 604 */ 605 static inline int PageTransTail(struct page *page) 606 { 607 return PageTail(page); 608 } 609 610 /* 611 * PageDoubleMap indicates that the compound page is mapped with PTEs as well 612 * as PMDs. 613 * 614 * This is required for optimization of rmap operations for THP: we can postpone 615 * per small page mapcount accounting (and its overhead from atomic operations) 616 * until the first PMD split. 617 * 618 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up 619 * by one. This reference will go away with last compound_mapcount. 620 * 621 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap(). 622 */ 623 static inline int PageDoubleMap(struct page *page) 624 { 625 return PageHead(page) && test_bit(PG_double_map, &page[1].flags); 626 } 627 628 static inline void SetPageDoubleMap(struct page *page) 629 { 630 VM_BUG_ON_PAGE(!PageHead(page), page); 631 set_bit(PG_double_map, &page[1].flags); 632 } 633 634 static inline void ClearPageDoubleMap(struct page *page) 635 { 636 VM_BUG_ON_PAGE(!PageHead(page), page); 637 clear_bit(PG_double_map, &page[1].flags); 638 } 639 static inline int TestSetPageDoubleMap(struct page *page) 640 { 641 VM_BUG_ON_PAGE(!PageHead(page), page); 642 return test_and_set_bit(PG_double_map, &page[1].flags); 643 } 644 645 static inline int TestClearPageDoubleMap(struct page *page) 646 { 647 VM_BUG_ON_PAGE(!PageHead(page), page); 648 return test_and_clear_bit(PG_double_map, &page[1].flags); 649 } 650 651 #else 652 TESTPAGEFLAG_FALSE(TransHuge) 653 TESTPAGEFLAG_FALSE(TransCompound) 654 TESTPAGEFLAG_FALSE(TransCompoundMap) 655 TESTPAGEFLAG_FALSE(TransTail) 656 PAGEFLAG_FALSE(DoubleMap) 657 TESTSETFLAG_FALSE(DoubleMap) 658 TESTCLEARFLAG_FALSE(DoubleMap) 659 #endif 660 661 /* 662 * For pages that are never mapped to userspace (and aren't PageSlab), 663 * page_type may be used. Because it is initialised to -1, we invert the 664 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and 665 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and 666 * low bits so that an underflow or overflow of page_mapcount() won't be 667 * mistaken for a page type value. 668 */ 669 670 #define PAGE_TYPE_BASE 0xf0000000 671 /* Reserve 0x0000007f to catch underflows of page_mapcount */ 672 #define PAGE_MAPCOUNT_RESERVE -128 673 #define PG_buddy 0x00000080 674 #define PG_balloon 0x00000100 675 #define PG_kmemcg 0x00000200 676 #define PG_table 0x00000400 677 678 #define PageType(page, flag) \ 679 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) 680 681 static inline int page_has_type(struct page *page) 682 { 683 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE; 684 } 685 686 #define PAGE_TYPE_OPS(uname, lname) \ 687 static __always_inline int Page##uname(struct page *page) \ 688 { \ 689 return PageType(page, PG_##lname); \ 690 } \ 691 static __always_inline void __SetPage##uname(struct page *page) \ 692 { \ 693 VM_BUG_ON_PAGE(!PageType(page, 0), page); \ 694 page->page_type &= ~PG_##lname; \ 695 } \ 696 static __always_inline void __ClearPage##uname(struct page *page) \ 697 { \ 698 VM_BUG_ON_PAGE(!Page##uname(page), page); \ 699 page->page_type |= PG_##lname; \ 700 } 701 702 /* 703 * PageBuddy() indicates that the page is free and in the buddy system 704 * (see mm/page_alloc.c). 705 */ 706 PAGE_TYPE_OPS(Buddy, buddy) 707 708 /* 709 * PageBalloon() is true for pages that are on the balloon page list 710 * (see mm/balloon_compaction.c). 711 */ 712 PAGE_TYPE_OPS(Balloon, balloon) 713 714 /* 715 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on 716 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free. 717 */ 718 PAGE_TYPE_OPS(Kmemcg, kmemcg) 719 720 /* 721 * Marks pages in use as page tables. 722 */ 723 PAGE_TYPE_OPS(Table, table) 724 725 extern bool is_free_buddy_page(struct page *page); 726 727 __PAGEFLAG(Isolated, isolated, PF_ANY); 728 729 /* 730 * If network-based swap is enabled, sl*b must keep track of whether pages 731 * were allocated from pfmemalloc reserves. 732 */ 733 static inline int PageSlabPfmemalloc(struct page *page) 734 { 735 VM_BUG_ON_PAGE(!PageSlab(page), page); 736 return PageActive(page); 737 } 738 739 static inline void SetPageSlabPfmemalloc(struct page *page) 740 { 741 VM_BUG_ON_PAGE(!PageSlab(page), page); 742 SetPageActive(page); 743 } 744 745 static inline void __ClearPageSlabPfmemalloc(struct page *page) 746 { 747 VM_BUG_ON_PAGE(!PageSlab(page), page); 748 __ClearPageActive(page); 749 } 750 751 static inline void ClearPageSlabPfmemalloc(struct page *page) 752 { 753 VM_BUG_ON_PAGE(!PageSlab(page), page); 754 ClearPageActive(page); 755 } 756 757 #ifdef CONFIG_MMU 758 #define __PG_MLOCKED (1UL << PG_mlocked) 759 #else 760 #define __PG_MLOCKED 0 761 #endif 762 763 /* 764 * Flags checked when a page is freed. Pages being freed should not have 765 * these flags set. It they are, there is a problem. 766 */ 767 #define PAGE_FLAGS_CHECK_AT_FREE \ 768 (1UL << PG_lru | 1UL << PG_locked | \ 769 1UL << PG_private | 1UL << PG_private_2 | \ 770 1UL << PG_writeback | 1UL << PG_reserved | \ 771 1UL << PG_slab | 1UL << PG_active | \ 772 1UL << PG_unevictable | __PG_MLOCKED) 773 774 /* 775 * Flags checked when a page is prepped for return by the page allocator. 776 * Pages being prepped should not have these flags set. It they are set, 777 * there has been a kernel bug or struct page corruption. 778 * 779 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's 780 * alloc-free cycle to prevent from reusing the page. 781 */ 782 #define PAGE_FLAGS_CHECK_AT_PREP \ 783 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON) 784 785 #define PAGE_FLAGS_PRIVATE \ 786 (1UL << PG_private | 1UL << PG_private_2) 787 /** 788 * page_has_private - Determine if page has private stuff 789 * @page: The page to be checked 790 * 791 * Determine if a page has private stuff, indicating that release routines 792 * should be invoked upon it. 793 */ 794 static inline int page_has_private(struct page *page) 795 { 796 return !!(page->flags & PAGE_FLAGS_PRIVATE); 797 } 798 799 #undef PF_ANY 800 #undef PF_HEAD 801 #undef PF_ONLY_HEAD 802 #undef PF_NO_TAIL 803 #undef PF_NO_COMPOUND 804 #endif /* !__GENERATING_BOUNDS_H */ 805 806 #endif /* PAGE_FLAGS_H */ 807