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. The "struct page" of such a page 21 * should in general not be touched (e.g. set dirty) except by its owner. 22 * Pages marked as PG_reserved include: 23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS, 24 * initrd, HW tables) 25 * - Pages reserved or allocated early during boot (before the page allocator 26 * was initialized). This includes (depending on the architecture) the 27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much 28 * much more. Once (if ever) freed, PG_reserved is cleared and they will 29 * be given to the page allocator. 30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying 31 * to read/write these pages might end badly. Don't touch! 32 * - The zero page(s) 33 * - Pages not added to the page allocator when onlining a section because 34 * they were excluded via the online_page_callback() or because they are 35 * PG_hwpoison. 36 * - Pages allocated in the context of kexec/kdump (loaded kernel image, 37 * control pages, vmcoreinfo) 38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are 39 * not marked PG_reserved (as they might be in use by somebody else who does 40 * not respect the caching strategy). 41 * - Pages part of an offline section (struct pages of offline sections should 42 * not be trusted as they will be initialized when first onlined). 43 * - MCA pages on ia64 44 * - Pages holding CPU notes for POWER Firmware Assisted Dump 45 * - Device memory (e.g. PMEM, DAX, HMM) 46 * Some PG_reserved pages will be excluded from the hibernation image. 47 * PG_reserved does in general not hinder anybody from dumping or swapping 48 * and is no longer required for remap_pfn_range(). ioremap might require it. 49 * Consequently, PG_reserved for a page mapped into user space can indicate 50 * the zero page, the vDSO, MMIO pages or device memory. 51 * 52 * The PG_private bitflag is set on pagecache pages if they contain filesystem 53 * specific data (which is normally at page->private). It can be used by 54 * private allocations for its own usage. 55 * 56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O 57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback 58 * is set before writeback starts and cleared when it finishes. 59 * 60 * PG_locked also pins a page in pagecache, and blocks truncation of the file 61 * while it is held. 62 * 63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page 64 * to become unlocked. 65 * 66 * PG_swapbacked is set when a page uses swap as a backing storage. This are 67 * usually PageAnon or shmem pages but please note that even anonymous pages 68 * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as 69 * a result of MADV_FREE). 70 * 71 * PG_uptodate tells whether the page's contents is valid. When a read 72 * completes, the page becomes uptodate, unless a disk I/O error happened. 73 * 74 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and 75 * file-backed pagecache (see mm/vmscan.c). 76 * 77 * PG_error is set to indicate that an I/O error occurred on this page. 78 * 79 * PG_arch_1 is an architecture specific page state bit. The generic code 80 * guarantees that this bit is cleared for a page when it first is entered into 81 * the page cache. 82 * 83 * PG_hwpoison indicates that a page got corrupted in hardware and contains 84 * data with incorrect ECC bits that triggered a machine check. Accessing is 85 * not safe since it may cause another machine check. Don't touch! 86 */ 87 88 /* 89 * Don't use the pageflags directly. Use the PageFoo macros. 90 * 91 * The page flags field is split into two parts, the main flags area 92 * which extends from the low bits upwards, and the fields area which 93 * extends from the high bits downwards. 94 * 95 * | FIELD | ... | FLAGS | 96 * N-1 ^ 0 97 * (NR_PAGEFLAGS) 98 * 99 * The fields area is reserved for fields mapping zone, node (for NUMA) and 100 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like 101 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). 102 */ 103 enum pageflags { 104 PG_locked, /* Page is locked. Don't touch. */ 105 PG_referenced, 106 PG_uptodate, 107 PG_dirty, 108 PG_lru, 109 PG_active, 110 PG_workingset, 111 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */ 112 PG_error, 113 PG_slab, 114 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ 115 PG_arch_1, 116 PG_reserved, 117 PG_private, /* If pagecache, has fs-private data */ 118 PG_private_2, /* If pagecache, has fs aux data */ 119 PG_writeback, /* Page is under writeback */ 120 PG_head, /* A head page */ 121 PG_mappedtodisk, /* Has blocks allocated on-disk */ 122 PG_reclaim, /* To be reclaimed asap */ 123 PG_swapbacked, /* Page is backed by RAM/swap */ 124 PG_unevictable, /* Page is "unevictable" */ 125 #ifdef CONFIG_MMU 126 PG_mlocked, /* Page is vma mlocked */ 127 #endif 128 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 129 PG_uncached, /* Page has been mapped as uncached */ 130 #endif 131 #ifdef CONFIG_MEMORY_FAILURE 132 PG_hwpoison, /* hardware poisoned page. Don't touch */ 133 #endif 134 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 135 PG_young, 136 PG_idle, 137 #endif 138 #ifdef CONFIG_64BIT 139 PG_arch_2, 140 #endif 141 __NR_PAGEFLAGS, 142 143 /* Filesystems */ 144 PG_checked = PG_owner_priv_1, 145 146 /* SwapBacked */ 147 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ 148 149 /* Two page bits are conscripted by FS-Cache to maintain local caching 150 * state. These bits are set on pages belonging to the netfs's inodes 151 * when those inodes are being locally cached. 152 */ 153 PG_fscache = PG_private_2, /* page backed by cache */ 154 155 /* XEN */ 156 /* Pinned in Xen as a read-only pagetable page. */ 157 PG_pinned = PG_owner_priv_1, 158 /* Pinned as part of domain save (see xen_mm_pin_all()). */ 159 PG_savepinned = PG_dirty, 160 /* Has a grant mapping of another (foreign) domain's page. */ 161 PG_foreign = PG_owner_priv_1, 162 /* Remapped by swiotlb-xen. */ 163 PG_xen_remapped = PG_owner_priv_1, 164 165 /* SLOB */ 166 PG_slob_free = PG_private, 167 168 /* Compound pages. Stored in first tail page's flags */ 169 PG_double_map = PG_workingset, 170 171 /* non-lru isolated movable page */ 172 PG_isolated = PG_reclaim, 173 174 /* Only valid for buddy pages. Used to track pages that are reported */ 175 PG_reported = PG_uptodate, 176 }; 177 178 #ifndef __GENERATING_BOUNDS_H 179 180 struct page; /* forward declaration */ 181 182 static inline struct page *compound_head(struct page *page) 183 { 184 unsigned long head = READ_ONCE(page->compound_head); 185 186 if (unlikely(head & 1)) 187 return (struct page *) (head - 1); 188 return page; 189 } 190 191 static __always_inline int PageTail(struct page *page) 192 { 193 return READ_ONCE(page->compound_head) & 1; 194 } 195 196 static __always_inline int PageCompound(struct page *page) 197 { 198 return test_bit(PG_head, &page->flags) || PageTail(page); 199 } 200 201 #define PAGE_POISON_PATTERN -1l 202 static inline int PagePoisoned(const struct page *page) 203 { 204 return page->flags == PAGE_POISON_PATTERN; 205 } 206 207 #ifdef CONFIG_DEBUG_VM 208 void page_init_poison(struct page *page, size_t size); 209 #else 210 static inline void page_init_poison(struct page *page, size_t size) 211 { 212 } 213 #endif 214 215 /* 216 * Page flags policies wrt compound pages 217 * 218 * PF_POISONED_CHECK 219 * check if this struct page poisoned/uninitialized 220 * 221 * PF_ANY: 222 * the page flag is relevant for small, head and tail pages. 223 * 224 * PF_HEAD: 225 * for compound page all operations related to the page flag applied to 226 * head page. 227 * 228 * PF_ONLY_HEAD: 229 * for compound page, callers only ever operate on the head page. 230 * 231 * PF_NO_TAIL: 232 * modifications of the page flag must be done on small or head pages, 233 * checks can be done on tail pages too. 234 * 235 * PF_NO_COMPOUND: 236 * the page flag is not relevant for compound pages. 237 * 238 * PF_SECOND: 239 * the page flag is stored in the first tail page. 240 */ 241 #define PF_POISONED_CHECK(page) ({ \ 242 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \ 243 page; }) 244 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page) 245 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page)) 246 #define PF_ONLY_HEAD(page, enforce) ({ \ 247 VM_BUG_ON_PGFLAGS(PageTail(page), page); \ 248 PF_POISONED_CHECK(page); }) 249 #define PF_NO_TAIL(page, enforce) ({ \ 250 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ 251 PF_POISONED_CHECK(compound_head(page)); }) 252 #define PF_NO_COMPOUND(page, enforce) ({ \ 253 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \ 254 PF_POISONED_CHECK(page); }) 255 #define PF_SECOND(page, enforce) ({ \ 256 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \ 257 PF_POISONED_CHECK(&page[1]); }) 258 259 /* 260 * Macros to create function definitions for page flags 261 */ 262 #define TESTPAGEFLAG(uname, lname, policy) \ 263 static __always_inline int Page##uname(struct page *page) \ 264 { return test_bit(PG_##lname, &policy(page, 0)->flags); } 265 266 #define SETPAGEFLAG(uname, lname, policy) \ 267 static __always_inline void SetPage##uname(struct page *page) \ 268 { set_bit(PG_##lname, &policy(page, 1)->flags); } 269 270 #define CLEARPAGEFLAG(uname, lname, policy) \ 271 static __always_inline void ClearPage##uname(struct page *page) \ 272 { clear_bit(PG_##lname, &policy(page, 1)->flags); } 273 274 #define __SETPAGEFLAG(uname, lname, policy) \ 275 static __always_inline void __SetPage##uname(struct page *page) \ 276 { __set_bit(PG_##lname, &policy(page, 1)->flags); } 277 278 #define __CLEARPAGEFLAG(uname, lname, policy) \ 279 static __always_inline void __ClearPage##uname(struct page *page) \ 280 { __clear_bit(PG_##lname, &policy(page, 1)->flags); } 281 282 #define TESTSETFLAG(uname, lname, policy) \ 283 static __always_inline int TestSetPage##uname(struct page *page) \ 284 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); } 285 286 #define TESTCLEARFLAG(uname, lname, policy) \ 287 static __always_inline int TestClearPage##uname(struct page *page) \ 288 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); } 289 290 #define PAGEFLAG(uname, lname, policy) \ 291 TESTPAGEFLAG(uname, lname, policy) \ 292 SETPAGEFLAG(uname, lname, policy) \ 293 CLEARPAGEFLAG(uname, lname, policy) 294 295 #define __PAGEFLAG(uname, lname, policy) \ 296 TESTPAGEFLAG(uname, lname, policy) \ 297 __SETPAGEFLAG(uname, lname, policy) \ 298 __CLEARPAGEFLAG(uname, lname, policy) 299 300 #define TESTSCFLAG(uname, lname, policy) \ 301 TESTSETFLAG(uname, lname, policy) \ 302 TESTCLEARFLAG(uname, lname, policy) 303 304 #define TESTPAGEFLAG_FALSE(uname) \ 305 static inline int Page##uname(const struct page *page) { return 0; } 306 307 #define SETPAGEFLAG_NOOP(uname) \ 308 static inline void SetPage##uname(struct page *page) { } 309 310 #define CLEARPAGEFLAG_NOOP(uname) \ 311 static inline void ClearPage##uname(struct page *page) { } 312 313 #define __CLEARPAGEFLAG_NOOP(uname) \ 314 static inline void __ClearPage##uname(struct page *page) { } 315 316 #define TESTSETFLAG_FALSE(uname) \ 317 static inline int TestSetPage##uname(struct page *page) { return 0; } 318 319 #define TESTCLEARFLAG_FALSE(uname) \ 320 static inline int TestClearPage##uname(struct page *page) { return 0; } 321 322 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \ 323 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname) 324 325 #define TESTSCFLAG_FALSE(uname) \ 326 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname) 327 328 __PAGEFLAG(Locked, locked, PF_NO_TAIL) 329 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) 330 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL) 331 PAGEFLAG(Referenced, referenced, PF_HEAD) 332 TESTCLEARFLAG(Referenced, referenced, PF_HEAD) 333 __SETPAGEFLAG(Referenced, referenced, PF_HEAD) 334 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD) 335 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD) 336 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD) 337 TESTCLEARFLAG(LRU, lru, PF_HEAD) 338 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) 339 TESTCLEARFLAG(Active, active, PF_HEAD) 340 PAGEFLAG(Workingset, workingset, PF_HEAD) 341 TESTCLEARFLAG(Workingset, workingset, PF_HEAD) 342 __PAGEFLAG(Slab, slab, PF_NO_TAIL) 343 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL) 344 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */ 345 346 /* Xen */ 347 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND) 348 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND) 349 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND); 350 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND); 351 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND) 352 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND) 353 354 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 355 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 356 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) 357 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 358 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 359 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) 360 361 /* 362 * Private page markings that may be used by the filesystem that owns the page 363 * for its own purposes. 364 * - PG_private and PG_private_2 cause releasepage() and co to be invoked 365 */ 366 PAGEFLAG(Private, private, PF_ANY) 367 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY) 368 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 369 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY) 370 371 /* 372 * Only test-and-set exist for PG_writeback. The unconditional operators are 373 * risky: they bypass page accounting. 374 */ 375 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL) 376 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL) 377 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL) 378 379 /* PG_readahead is only used for reads; PG_reclaim is only for writes */ 380 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) 381 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) 382 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) 383 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND) 384 385 #ifdef CONFIG_HIGHMEM 386 /* 387 * Must use a macro here due to header dependency issues. page_zone() is not 388 * available at this point. 389 */ 390 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) 391 #else 392 PAGEFLAG_FALSE(HighMem) 393 #endif 394 395 #ifdef CONFIG_SWAP 396 static __always_inline int PageSwapCache(struct page *page) 397 { 398 #ifdef CONFIG_THP_SWAP 399 page = compound_head(page); 400 #endif 401 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); 402 403 } 404 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 405 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) 406 #else 407 PAGEFLAG_FALSE(SwapCache) 408 #endif 409 410 PAGEFLAG(Unevictable, unevictable, PF_HEAD) 411 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD) 412 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD) 413 414 #ifdef CONFIG_MMU 415 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 416 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) 417 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL) 418 #else 419 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked) 420 TESTSCFLAG_FALSE(Mlocked) 421 #endif 422 423 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 424 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND) 425 #else 426 PAGEFLAG_FALSE(Uncached) 427 #endif 428 429 #ifdef CONFIG_MEMORY_FAILURE 430 PAGEFLAG(HWPoison, hwpoison, PF_ANY) 431 TESTSCFLAG(HWPoison, hwpoison, PF_ANY) 432 #define __PG_HWPOISON (1UL << PG_hwpoison) 433 extern bool take_page_off_buddy(struct page *page); 434 #else 435 PAGEFLAG_FALSE(HWPoison) 436 #define __PG_HWPOISON 0 437 #endif 438 439 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT) 440 TESTPAGEFLAG(Young, young, PF_ANY) 441 SETPAGEFLAG(Young, young, PF_ANY) 442 TESTCLEARFLAG(Young, young, PF_ANY) 443 PAGEFLAG(Idle, idle, PF_ANY) 444 #endif 445 446 /* 447 * PageReported() is used to track reported free pages within the Buddy 448 * allocator. We can use the non-atomic version of the test and set 449 * operations as both should be shielded with the zone lock to prevent 450 * any possible races on the setting or clearing of the bit. 451 */ 452 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND) 453 454 /* 455 * On an anonymous page mapped into a user virtual memory area, 456 * page->mapping points to its anon_vma, not to a struct address_space; 457 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h. 458 * 459 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled, 460 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON 461 * bit; and then page->mapping points, not to an anon_vma, but to a private 462 * structure which KSM associates with that merged page. See ksm.h. 463 * 464 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable 465 * page and then page->mapping points a struct address_space. 466 * 467 * Please note that, confusingly, "page_mapping" refers to the inode 468 * address_space which maps the page from disk; whereas "page_mapped" 469 * refers to user virtual address space into which the page is mapped. 470 */ 471 #define PAGE_MAPPING_ANON 0x1 472 #define PAGE_MAPPING_MOVABLE 0x2 473 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 474 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) 475 476 static __always_inline int PageMappingFlags(struct page *page) 477 { 478 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0; 479 } 480 481 static __always_inline int PageAnon(struct page *page) 482 { 483 page = compound_head(page); 484 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0; 485 } 486 487 static __always_inline int __PageMovable(struct page *page) 488 { 489 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 490 PAGE_MAPPING_MOVABLE; 491 } 492 493 #ifdef CONFIG_KSM 494 /* 495 * A KSM page is one of those write-protected "shared pages" or "merged pages" 496 * which KSM maps into multiple mms, wherever identical anonymous page content 497 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any 498 * anon_vma, but to that page's node of the stable tree. 499 */ 500 static __always_inline int PageKsm(struct page *page) 501 { 502 page = compound_head(page); 503 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == 504 PAGE_MAPPING_KSM; 505 } 506 #else 507 TESTPAGEFLAG_FALSE(Ksm) 508 #endif 509 510 u64 stable_page_flags(struct page *page); 511 512 static inline int PageUptodate(struct page *page) 513 { 514 int ret; 515 page = compound_head(page); 516 ret = test_bit(PG_uptodate, &(page)->flags); 517 /* 518 * Must ensure that the data we read out of the page is loaded 519 * _after_ we've loaded page->flags to check for PageUptodate. 520 * We can skip the barrier if the page is not uptodate, because 521 * we wouldn't be reading anything from it. 522 * 523 * See SetPageUptodate() for the other side of the story. 524 */ 525 if (ret) 526 smp_rmb(); 527 528 return ret; 529 } 530 531 static __always_inline void __SetPageUptodate(struct page *page) 532 { 533 VM_BUG_ON_PAGE(PageTail(page), page); 534 smp_wmb(); 535 __set_bit(PG_uptodate, &page->flags); 536 } 537 538 static __always_inline void SetPageUptodate(struct page *page) 539 { 540 VM_BUG_ON_PAGE(PageTail(page), page); 541 /* 542 * Memory barrier must be issued before setting the PG_uptodate bit, 543 * so that all previous stores issued in order to bring the page 544 * uptodate are actually visible before PageUptodate becomes true. 545 */ 546 smp_wmb(); 547 set_bit(PG_uptodate, &page->flags); 548 } 549 550 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL) 551 552 int test_clear_page_writeback(struct page *page); 553 int __test_set_page_writeback(struct page *page, bool keep_write); 554 555 #define test_set_page_writeback(page) \ 556 __test_set_page_writeback(page, false) 557 #define test_set_page_writeback_keepwrite(page) \ 558 __test_set_page_writeback(page, true) 559 560 static inline void set_page_writeback(struct page *page) 561 { 562 test_set_page_writeback(page); 563 } 564 565 static inline void set_page_writeback_keepwrite(struct page *page) 566 { 567 test_set_page_writeback_keepwrite(page); 568 } 569 570 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY) 571 572 static __always_inline void set_compound_head(struct page *page, struct page *head) 573 { 574 WRITE_ONCE(page->compound_head, (unsigned long)head + 1); 575 } 576 577 static __always_inline void clear_compound_head(struct page *page) 578 { 579 WRITE_ONCE(page->compound_head, 0); 580 } 581 582 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 583 static inline void ClearPageCompound(struct page *page) 584 { 585 BUG_ON(!PageHead(page)); 586 ClearPageHead(page); 587 } 588 #endif 589 590 #define PG_head_mask ((1UL << PG_head)) 591 592 #ifdef CONFIG_HUGETLB_PAGE 593 int PageHuge(struct page *page); 594 int PageHeadHuge(struct page *page); 595 bool page_huge_active(struct page *page); 596 #else 597 TESTPAGEFLAG_FALSE(Huge) 598 TESTPAGEFLAG_FALSE(HeadHuge) 599 600 static inline bool page_huge_active(struct page *page) 601 { 602 return 0; 603 } 604 #endif 605 606 607 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 608 /* 609 * PageHuge() only returns true for hugetlbfs pages, but not for 610 * normal or transparent huge pages. 611 * 612 * PageTransHuge() returns true for both transparent huge and 613 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be 614 * called only in the core VM paths where hugetlbfs pages can't exist. 615 */ 616 static inline int PageTransHuge(struct page *page) 617 { 618 VM_BUG_ON_PAGE(PageTail(page), page); 619 return PageHead(page); 620 } 621 622 /* 623 * PageTransCompound returns true for both transparent huge pages 624 * and hugetlbfs pages, so it should only be called when it's known 625 * that hugetlbfs pages aren't involved. 626 */ 627 static inline int PageTransCompound(struct page *page) 628 { 629 return PageCompound(page); 630 } 631 632 /* 633 * PageTransCompoundMap is the same as PageTransCompound, but it also 634 * guarantees the primary MMU has the entire compound page mapped 635 * through pmd_trans_huge, which in turn guarantees the secondary MMUs 636 * can also map the entire compound page. This allows the secondary 637 * MMUs to call get_user_pages() only once for each compound page and 638 * to immediately map the entire compound page with a single secondary 639 * MMU fault. If there will be a pmd split later, the secondary MMUs 640 * will get an update through the MMU notifier invalidation through 641 * split_huge_pmd(). 642 * 643 * Unlike PageTransCompound, this is safe to be called only while 644 * split_huge_pmd() cannot run from under us, like if protected by the 645 * MMU notifier, otherwise it may result in page->_mapcount check false 646 * positives. 647 * 648 * We have to treat page cache THP differently since every subpage of it 649 * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE 650 * mapped in the current process so comparing subpage's _mapcount to 651 * compound_mapcount to filter out PTE mapped case. 652 */ 653 static inline int PageTransCompoundMap(struct page *page) 654 { 655 struct page *head; 656 657 if (!PageTransCompound(page)) 658 return 0; 659 660 if (PageAnon(page)) 661 return atomic_read(&page->_mapcount) < 0; 662 663 head = compound_head(page); 664 /* File THP is PMD mapped and not PTE mapped */ 665 return atomic_read(&page->_mapcount) == 666 atomic_read(compound_mapcount_ptr(head)); 667 } 668 669 /* 670 * PageTransTail returns true for both transparent huge pages 671 * and hugetlbfs pages, so it should only be called when it's known 672 * that hugetlbfs pages aren't involved. 673 */ 674 static inline int PageTransTail(struct page *page) 675 { 676 return PageTail(page); 677 } 678 679 /* 680 * PageDoubleMap indicates that the compound page is mapped with PTEs as well 681 * as PMDs. 682 * 683 * This is required for optimization of rmap operations for THP: we can postpone 684 * per small page mapcount accounting (and its overhead from atomic operations) 685 * until the first PMD split. 686 * 687 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up 688 * by one. This reference will go away with last compound_mapcount. 689 * 690 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap(). 691 */ 692 PAGEFLAG(DoubleMap, double_map, PF_SECOND) 693 TESTSCFLAG(DoubleMap, double_map, PF_SECOND) 694 #else 695 TESTPAGEFLAG_FALSE(TransHuge) 696 TESTPAGEFLAG_FALSE(TransCompound) 697 TESTPAGEFLAG_FALSE(TransCompoundMap) 698 TESTPAGEFLAG_FALSE(TransTail) 699 PAGEFLAG_FALSE(DoubleMap) 700 TESTSCFLAG_FALSE(DoubleMap) 701 #endif 702 703 /* 704 * For pages that are never mapped to userspace (and aren't PageSlab), 705 * page_type may be used. Because it is initialised to -1, we invert the 706 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and 707 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and 708 * low bits so that an underflow or overflow of page_mapcount() won't be 709 * mistaken for a page type value. 710 */ 711 712 #define PAGE_TYPE_BASE 0xf0000000 713 /* Reserve 0x0000007f to catch underflows of page_mapcount */ 714 #define PAGE_MAPCOUNT_RESERVE -128 715 #define PG_buddy 0x00000080 716 #define PG_offline 0x00000100 717 #define PG_table 0x00000200 718 #define PG_guard 0x00000400 719 720 #define PageType(page, flag) \ 721 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) 722 723 static inline int page_has_type(struct page *page) 724 { 725 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE; 726 } 727 728 #define PAGE_TYPE_OPS(uname, lname) \ 729 static __always_inline int Page##uname(struct page *page) \ 730 { \ 731 return PageType(page, PG_##lname); \ 732 } \ 733 static __always_inline void __SetPage##uname(struct page *page) \ 734 { \ 735 VM_BUG_ON_PAGE(!PageType(page, 0), page); \ 736 page->page_type &= ~PG_##lname; \ 737 } \ 738 static __always_inline void __ClearPage##uname(struct page *page) \ 739 { \ 740 VM_BUG_ON_PAGE(!Page##uname(page), page); \ 741 page->page_type |= PG_##lname; \ 742 } 743 744 /* 745 * PageBuddy() indicates that the page is free and in the buddy system 746 * (see mm/page_alloc.c). 747 */ 748 PAGE_TYPE_OPS(Buddy, buddy) 749 750 /* 751 * PageOffline() indicates that the page is logically offline although the 752 * containing section is online. (e.g. inflated in a balloon driver or 753 * not onlined when onlining the section). 754 * The content of these pages is effectively stale. Such pages should not 755 * be touched (read/write/dump/save) except by their owner. 756 * 757 * If a driver wants to allow to offline unmovable PageOffline() pages without 758 * putting them back to the buddy, it can do so via the memory notifier by 759 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the 760 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline() 761 * pages (now with a reference count of zero) are treated like free pages, 762 * allowing the containing memory block to get offlined. A driver that 763 * relies on this feature is aware that re-onlining the memory block will 764 * require to re-set the pages PageOffline() and not giving them to the 765 * buddy via online_page_callback_t. 766 */ 767 PAGE_TYPE_OPS(Offline, offline) 768 769 /* 770 * Marks pages in use as page tables. 771 */ 772 PAGE_TYPE_OPS(Table, table) 773 774 /* 775 * Marks guardpages used with debug_pagealloc. 776 */ 777 PAGE_TYPE_OPS(Guard, guard) 778 779 extern bool is_free_buddy_page(struct page *page); 780 781 __PAGEFLAG(Isolated, isolated, PF_ANY); 782 783 /* 784 * If network-based swap is enabled, sl*b must keep track of whether pages 785 * were allocated from pfmemalloc reserves. 786 */ 787 static inline int PageSlabPfmemalloc(struct page *page) 788 { 789 VM_BUG_ON_PAGE(!PageSlab(page), page); 790 return PageActive(page); 791 } 792 793 static inline void SetPageSlabPfmemalloc(struct page *page) 794 { 795 VM_BUG_ON_PAGE(!PageSlab(page), page); 796 SetPageActive(page); 797 } 798 799 static inline void __ClearPageSlabPfmemalloc(struct page *page) 800 { 801 VM_BUG_ON_PAGE(!PageSlab(page), page); 802 __ClearPageActive(page); 803 } 804 805 static inline void ClearPageSlabPfmemalloc(struct page *page) 806 { 807 VM_BUG_ON_PAGE(!PageSlab(page), page); 808 ClearPageActive(page); 809 } 810 811 #ifdef CONFIG_MMU 812 #define __PG_MLOCKED (1UL << PG_mlocked) 813 #else 814 #define __PG_MLOCKED 0 815 #endif 816 817 /* 818 * Flags checked when a page is freed. Pages being freed should not have 819 * these flags set. It they are, there is a problem. 820 */ 821 #define PAGE_FLAGS_CHECK_AT_FREE \ 822 (1UL << PG_lru | 1UL << PG_locked | \ 823 1UL << PG_private | 1UL << PG_private_2 | \ 824 1UL << PG_writeback | 1UL << PG_reserved | \ 825 1UL << PG_slab | 1UL << PG_active | \ 826 1UL << PG_unevictable | __PG_MLOCKED) 827 828 /* 829 * Flags checked when a page is prepped for return by the page allocator. 830 * Pages being prepped should not have these flags set. It they are set, 831 * there has been a kernel bug or struct page corruption. 832 * 833 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's 834 * alloc-free cycle to prevent from reusing the page. 835 */ 836 #define PAGE_FLAGS_CHECK_AT_PREP \ 837 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON) 838 839 #define PAGE_FLAGS_PRIVATE \ 840 (1UL << PG_private | 1UL << PG_private_2) 841 /** 842 * page_has_private - Determine if page has private stuff 843 * @page: The page to be checked 844 * 845 * Determine if a page has private stuff, indicating that release routines 846 * should be invoked upon it. 847 */ 848 static inline int page_has_private(struct page *page) 849 { 850 return !!(page->flags & PAGE_FLAGS_PRIVATE); 851 } 852 853 #undef PF_ANY 854 #undef PF_HEAD 855 #undef PF_ONLY_HEAD 856 #undef PF_NO_TAIL 857 #undef PF_NO_COMPOUND 858 #undef PF_SECOND 859 #endif /* !__GENERATING_BOUNDS_H */ 860 861 #endif /* PAGE_FLAGS_H */ 862