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