include/linux/page-flags.h

   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_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 135         PG_young,
 136         PG_idle,
 137 #endif
 138 #ifdef CONFIG_64BIT
 139         PG_arch_2,
 140 #endif
 141 #ifdef CONFIG_KASAN_HW_TAGS
 142         PG_skip_kasan_poison,
 143 #endif
 144         __NR_PAGEFLAGS,
 145
 146         /* Filesystems */
 147         PG_checked = PG_owner_priv_1,
 148
 149         /* SwapBacked */
 150         PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
 151
 152         /* Two page bits are conscripted by FS-Cache to maintain local caching
 153          * state.  These bits are set on pages belonging to the netfs's inodes
 154          * when those inodes are being locally cached.
 155          */
 156         PG_fscache = PG_private_2,      /* page backed by cache */
 157
 158         /* XEN */
 159         /* Pinned in Xen as a read-only pagetable page. */
 160         PG_pinned = PG_owner_priv_1,
 161         /* Pinned as part of domain save (see xen_mm_pin_all()). */
 162         PG_savepinned = PG_dirty,
 163         /* Has a grant mapping of another (foreign) domain's page. */
 164         PG_foreign = PG_owner_priv_1,
 165         /* Remapped by swiotlb-xen. */
 166         PG_xen_remapped = PG_owner_priv_1,
 167
 168         /* SLOB */
 169         PG_slob_free = PG_private,
 170
 171         /* Compound pages. Stored in first tail page's flags */
 172         PG_double_map = PG_workingset,
 173
 174         /* non-lru isolated movable page */
 175         PG_isolated = PG_reclaim,
 176
 177         /* Only valid for buddy pages. Used to track pages that are reported */
 178         PG_reported = PG_uptodate,
 179 };
 180
 181 #define PAGEFLAGS_MASK          ((1UL << NR_PAGEFLAGS) - 1)
 182
 183 #ifndef __GENERATING_BOUNDS_H
 184
 185 static inline unsigned long _compound_head(const struct page *page)
 186 {
 187         unsigned long head = READ_ONCE(page->compound_head);
 188
 189         if (unlikely(head & 1))
 190                 return head - 1;
 191         return (unsigned long)page;
 192 }
 193
 194 #define compound_head(page)     ((typeof(page))_compound_head(page))
 195
 196 static __always_inline int PageTail(struct page *page)
 197 {
 198         return READ_ONCE(page->compound_head) & 1;
 199 }
 200
 201 static __always_inline int PageCompound(struct page *page)
 202 {
 203         return test_bit(PG_head, &page->flags) || PageTail(page);
 204 }
 205
 206 #define PAGE_POISON_PATTERN     -1l
 207 static inline int PagePoisoned(const struct page *page)
 208 {
 209         return page->flags == PAGE_POISON_PATTERN;
 210 }
 211
 212 #ifdef CONFIG_DEBUG_VM
 213 void page_init_poison(struct page *page, size_t size);
 214 #else
 215 static inline void page_init_poison(struct page *page, size_t size)
 216 {
 217 }
 218 #endif
 219
 220 /*
 221  * Page flags policies wrt compound pages
 222  *
 223  * PF_POISONED_CHECK
 224  *     check if this struct page poisoned/uninitialized
 225  *
 226  * PF_ANY:
 227  *     the page flag is relevant for small, head and tail pages.
 228  *
 229  * PF_HEAD:
 230  *     for compound page all operations related to the page flag applied to
 231  *     head page.
 232  *
 233  * PF_ONLY_HEAD:
 234  *     for compound page, callers only ever operate on the head page.
 235  *
 236  * PF_NO_TAIL:
 237  *     modifications of the page flag must be done on small or head pages,
 238  *     checks can be done on tail pages too.
 239  *
 240  * PF_NO_COMPOUND:
 241  *     the page flag is not relevant for compound pages.
 242  *
 243  * PF_SECOND:
 244  *     the page flag is stored in the first tail page.
 245  */
 246 #define PF_POISONED_CHECK(page) ({                                      \
 247                 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page);            \
 248                 page; })
 249 #define PF_ANY(page, enforce)   PF_POISONED_CHECK(page)
 250 #define PF_HEAD(page, enforce)  PF_POISONED_CHECK(compound_head(page))
 251 #define PF_ONLY_HEAD(page, enforce) ({                                  \
 252                 VM_BUG_ON_PGFLAGS(PageTail(page), page);                \
 253                 PF_POISONED_CHECK(page); })
 254 #define PF_NO_TAIL(page, enforce) ({                                    \
 255                 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);     \
 256                 PF_POISONED_CHECK(compound_head(page)); })
 257 #define PF_NO_COMPOUND(page, enforce) ({                                \
 258                 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
 259                 PF_POISONED_CHECK(page); })
 260 #define PF_SECOND(page, enforce) ({                                     \
 261                 VM_BUG_ON_PGFLAGS(!PageHead(page), page);               \
 262                 PF_POISONED_CHECK(&page[1]); })
 263
 264 /*
 265  * Macros to create function definitions for page flags
 266  */
 267 #define TESTPAGEFLAG(uname, lname, policy)                              \
 268 static __always_inline int Page##uname(struct page *page)               \
 269         { return test_bit(PG_##lname, &policy(page, 0)->flags); }
 270
 271 #define SETPAGEFLAG(uname, lname, policy)                               \
 272 static __always_inline void SetPage##uname(struct page *page)           \
 273         { set_bit(PG_##lname, &policy(page, 1)->flags); }
 274
 275 #define CLEARPAGEFLAG(uname, lname, policy)                             \
 276 static __always_inline void ClearPage##uname(struct page *page)         \
 277         { clear_bit(PG_##lname, &policy(page, 1)->flags); }
 278
 279 #define __SETPAGEFLAG(uname, lname, policy)                             \
 280 static __always_inline void __SetPage##uname(struct page *page)         \
 281         { __set_bit(PG_##lname, &policy(page, 1)->flags); }
 282
 283 #define __CLEARPAGEFLAG(uname, lname, policy)                           \
 284 static __always_inline void __ClearPage##uname(struct page *page)       \
 285         { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
 286
 287 #define TESTSETFLAG(uname, lname, policy)                               \
 288 static __always_inline int TestSetPage##uname(struct page *page)        \
 289         { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
 290
 291 #define TESTCLEARFLAG(uname, lname, policy)                             \
 292 static __always_inline int TestClearPage##uname(struct page *page)      \
 293         { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 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 __PAGEFLAG(uname, lname, policy)                                \
 301         TESTPAGEFLAG(uname, lname, policy)                              \
 302         __SETPAGEFLAG(uname, lname, policy)                             \
 303         __CLEARPAGEFLAG(uname, lname, policy)
 304
 305 #define TESTSCFLAG(uname, lname, policy)                                \
 306         TESTSETFLAG(uname, lname, policy)                               \
 307         TESTCLEARFLAG(uname, lname, policy)
 308
 309 #define TESTPAGEFLAG_FALSE(uname)                                       \
 310 static inline int Page##uname(const struct page *page) { return 0; }
 311
 312 #define SETPAGEFLAG_NOOP(uname)                                         \
 313 static inline void SetPage##uname(struct page *page) {  }
 314
 315 #define CLEARPAGEFLAG_NOOP(uname)                                       \
 316 static inline void ClearPage##uname(struct page *page) {  }
 317
 318 #define __CLEARPAGEFLAG_NOOP(uname)                                     \
 319 static inline void __ClearPage##uname(struct page *page) {  }
 320
 321 #define TESTSETFLAG_FALSE(uname)                                        \
 322 static inline int TestSetPage##uname(struct page *page) { return 0; }
 323
 324 #define TESTCLEARFLAG_FALSE(uname)                                      \
 325 static inline int TestClearPage##uname(struct page *page) { return 0; }
 326
 327 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)                 \
 328         SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
 329
 330 #define TESTSCFLAG_FALSE(uname)                                         \
 331         TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 332
 333 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 334 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
 335 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
 336 PAGEFLAG(Referenced, referenced, PF_HEAD)
 337         TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
 338         __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
 339 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
 340         __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
 341 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
 342         TESTCLEARFLAG(LRU, lru, PF_HEAD)
 343 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
 344         TESTCLEARFLAG(Active, active, PF_HEAD)
 345 PAGEFLAG(Workingset, workingset, PF_HEAD)
 346         TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
 347 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
 348 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
 349 PAGEFLAG(Checked, checked, PF_NO_COMPOUND)         /* Used by some filesystems */
 350
 351 /* Xen */
 352 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
 353         TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
 354 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
 355 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
 356 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
 357         TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
 358
 359 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 360         __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 361         __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 362 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 363         __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 364         __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 365
 366 /*
 367  * Private page markings that may be used by the filesystem that owns the page
 368  * for its own purposes.
 369  * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 370  */
 371 PAGEFLAG(Private, private, PF_ANY)
 372 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
 373 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 374         TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 375
 376 /*
 377  * Only test-and-set exist for PG_writeback.  The unconditional operators are
 378  * risky: they bypass page accounting.
 379  */
 380 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
 381         TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
 382 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
 383
 384 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 385 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
 386         TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
 387 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 388         TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 389
 390 #ifdef CONFIG_HIGHMEM
 391 /*
 392  * Must use a macro here due to header dependency issues. page_zone() is not
 393  * available at this point.
 394  */
 395 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
 396 #else
 397 PAGEFLAG_FALSE(HighMem)
 398 #endif
 399
 400 #ifdef CONFIG_SWAP
 401 static __always_inline int PageSwapCache(struct page *page)
 402 {
 403 #ifdef CONFIG_THP_SWAP
 404         page = compound_head(page);
 405 #endif
 406         return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
 407
 408 }
 409 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
 410 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
 411 #else
 412 PAGEFLAG_FALSE(SwapCache)
 413 #endif
 414
 415 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
 416         __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
 417         TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
 418
 419 #ifdef CONFIG_MMU
 420 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 421         __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 422         TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
 423 #else
 424 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
 425         TESTSCFLAG_FALSE(Mlocked)
 426 #endif
 427
 428 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 429 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
 430 #else
 431 PAGEFLAG_FALSE(Uncached)
 432 #endif
 433
 434 #ifdef CONFIG_MEMORY_FAILURE
 435 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 436 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 437 #define __PG_HWPOISON (1UL << PG_hwpoison)
 438 extern bool take_page_off_buddy(struct page *page);
 439 #else
 440 PAGEFLAG_FALSE(HWPoison)
 441 #define __PG_HWPOISON 0
 442 #endif
 443
 444 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 445 TESTPAGEFLAG(Young, young, PF_ANY)
 446 SETPAGEFLAG(Young, young, PF_ANY)
 447 TESTCLEARFLAG(Young, young, PF_ANY)
 448 PAGEFLAG(Idle, idle, PF_ANY)
 449 #endif
 450
 451 #ifdef CONFIG_KASAN_HW_TAGS
 452 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
 453 #else
 454 PAGEFLAG_FALSE(SkipKASanPoison)
 455 #endif
 456
 457 /*
 458  * PageReported() is used to track reported free pages within the Buddy
 459  * allocator. We can use the non-atomic version of the test and set
 460  * operations as both should be shielded with the zone lock to prevent
 461  * any possible races on the setting or clearing of the bit.
 462  */
 463 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
 464
 465 /*
 466  * On an anonymous page mapped into a user virtual memory area,
 467  * page->mapping points to its anon_vma, not to a struct address_space;
 468  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 469  *
 470  * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 471  * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
 472  * bit; and then page->mapping points, not to an anon_vma, but to a private
 473  * structure which KSM associates with that merged page.  See ksm.h.
 474  *
 475  * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
 476  * page and then page->mapping points a struct address_space.
 477  *
 478  * Please note that, confusingly, "page_mapping" refers to the inode
 479  * address_space which maps the page from disk; whereas "page_mapped"
 480  * refers to user virtual address space into which the page is mapped.
 481  */
 482 #define PAGE_MAPPING_ANON       0x1
 483 #define PAGE_MAPPING_MOVABLE    0x2
 484 #define PAGE_MAPPING_KSM        (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 485 #define PAGE_MAPPING_FLAGS      (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 486
 487 static __always_inline int PageMappingFlags(struct page *page)
 488 {
 489         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
 490 }
 491
 492 static __always_inline int PageAnon(struct page *page)
 493 {
 494         page = compound_head(page);
 495         return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 496 }
 497
 498 static __always_inline int __PageMovable(struct page *page)
 499 {
 500         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 501                                 PAGE_MAPPING_MOVABLE;
 502 }
 503
 504 #ifdef CONFIG_KSM
 505 /*
 506  * A KSM page is one of those write-protected "shared pages" or "merged pages"
 507  * which KSM maps into multiple mms, wherever identical anonymous page content
 508  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 509  * anon_vma, but to that page's node of the stable tree.
 510  */
 511 static __always_inline int PageKsm(struct page *page)
 512 {
 513         page = compound_head(page);
 514         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 515                                 PAGE_MAPPING_KSM;
 516 }
 517 #else
 518 TESTPAGEFLAG_FALSE(Ksm)
 519 #endif
 520
 521 u64 stable_page_flags(struct page *page);
 522
 523 static inline int PageUptodate(struct page *page)
 524 {
 525         int ret;
 526         page = compound_head(page);
 527         ret = test_bit(PG_uptodate, &(page)->flags);
 528         /*
 529          * Must ensure that the data we read out of the page is loaded
 530          * _after_ we've loaded page->flags to check for PageUptodate.
 531          * We can skip the barrier if the page is not uptodate, because
 532          * we wouldn't be reading anything from it.
 533          *
 534          * See SetPageUptodate() for the other side of the story.
 535          */
 536         if (ret)
 537                 smp_rmb();
 538
 539         return ret;
 540 }
 541
 542 static __always_inline void __SetPageUptodate(struct page *page)
 543 {
 544         VM_BUG_ON_PAGE(PageTail(page), page);
 545         smp_wmb();
 546         __set_bit(PG_uptodate, &page->flags);
 547 }
 548
 549 static __always_inline void SetPageUptodate(struct page *page)
 550 {
 551         VM_BUG_ON_PAGE(PageTail(page), page);
 552         /*
 553          * Memory barrier must be issued before setting the PG_uptodate bit,
 554          * so that all previous stores issued in order to bring the page
 555          * uptodate are actually visible before PageUptodate becomes true.
 556          */
 557         smp_wmb();
 558         set_bit(PG_uptodate, &page->flags);
 559 }
 560
 561 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
 562
 563 int test_clear_page_writeback(struct page *page);
 564 int __test_set_page_writeback(struct page *page, bool keep_write);
 565
 566 #define test_set_page_writeback(page)                   \
 567         __test_set_page_writeback(page, false)
 568 #define test_set_page_writeback_keepwrite(page) \
 569         __test_set_page_writeback(page, true)
 570
 571 static inline void set_page_writeback(struct page *page)
 572 {
 573         test_set_page_writeback(page);
 574 }
 575
 576 static inline void set_page_writeback_keepwrite(struct page *page)
 577 {
 578         test_set_page_writeback_keepwrite(page);
 579 }
 580
 581 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
 582
 583 static __always_inline void set_compound_head(struct page *page, struct page *head)
 584 {
 585         WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
 586 }
 587
 588 static __always_inline void clear_compound_head(struct page *page)
 589 {
 590         WRITE_ONCE(page->compound_head, 0);
 591 }
 592
 593 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 594 static inline void ClearPageCompound(struct page *page)
 595 {
 596         BUG_ON(!PageHead(page));
 597         ClearPageHead(page);
 598 }
 599 #endif
 600
 601 #define PG_head_mask ((1UL << PG_head))
 602
 603 #ifdef CONFIG_HUGETLB_PAGE
 604 int PageHuge(struct page *page);
 605 int PageHeadHuge(struct page *page);
 606 #else
 607 TESTPAGEFLAG_FALSE(Huge)
 608 TESTPAGEFLAG_FALSE(HeadHuge)
 609 #endif
 610
 611
 612 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 613 /*
 614  * PageHuge() only returns true for hugetlbfs pages, but not for
 615  * normal or transparent huge pages.
 616  *
 617  * PageTransHuge() returns true for both transparent huge and
 618  * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 619  * called only in the core VM paths where hugetlbfs pages can't exist.
 620  */
 621 static inline int PageTransHuge(struct page *page)
 622 {
 623         VM_BUG_ON_PAGE(PageTail(page), page);
 624         return PageHead(page);
 625 }
 626
 627 /*
 628  * PageTransCompound returns true for both transparent huge pages
 629  * and hugetlbfs pages, so it should only be called when it's known
 630  * that hugetlbfs pages aren't involved.
 631  */
 632 static inline int PageTransCompound(struct page *page)
 633 {
 634         return PageCompound(page);
 635 }
 636
 637 /*
 638  * PageTransTail returns true for both transparent huge pages
 639  * and hugetlbfs pages, so it should only be called when it's known
 640  * that hugetlbfs pages aren't involved.
 641  */
 642 static inline int PageTransTail(struct page *page)
 643 {
 644         return PageTail(page);
 645 }
 646
 647 /*
 648  * PageDoubleMap indicates that the compound page is mapped with PTEs as well
 649  * as PMDs.
 650  *
 651  * This is required for optimization of rmap operations for THP: we can postpone
 652  * per small page mapcount accounting (and its overhead from atomic operations)
 653  * until the first PMD split.
 654  *
 655  * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
 656  * by one. This reference will go away with last compound_mapcount.
 657  *
 658  * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
 659  */
 660 PAGEFLAG(DoubleMap, double_map, PF_SECOND)
 661         TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
 662 #else
 663 TESTPAGEFLAG_FALSE(TransHuge)
 664 TESTPAGEFLAG_FALSE(TransCompound)
 665 TESTPAGEFLAG_FALSE(TransCompoundMap)
 666 TESTPAGEFLAG_FALSE(TransTail)
 667 PAGEFLAG_FALSE(DoubleMap)
 668         TESTSCFLAG_FALSE(DoubleMap)
 669 #endif
 670
 671 /*
 672  * Check if a page is currently marked HWPoisoned. Note that this check is
 673  * best effort only and inherently racy: there is no way to synchronize with
 674  * failing hardware.
 675  */
 676 static inline bool is_page_hwpoison(struct page *page)
 677 {
 678         if (PageHWPoison(page))
 679                 return true;
 680         return PageHuge(page) && PageHWPoison(compound_head(page));
 681 }
 682
 683 /*
 684  * For pages that are never mapped to userspace (and aren't PageSlab),
 685  * page_type may be used.  Because it is initialised to -1, we invert the
 686  * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
 687  * __ClearPageFoo *sets* the bit used for PageFoo.  We reserve a few high and
 688  * low bits so that an underflow or overflow of page_mapcount() won't be
 689  * mistaken for a page type value.
 690  */
 691
 692 #define PAGE_TYPE_BASE  0xf0000000
 693 /* Reserve              0x0000007f to catch underflows of page_mapcount */
 694 #define PAGE_MAPCOUNT_RESERVE   -128
 695 #define PG_buddy        0x00000080
 696 #define PG_offline      0x00000100
 697 #define PG_table        0x00000200
 698 #define PG_guard        0x00000400
 699
 700 #define PageType(page, flag)                                            \
 701         ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
 702
 703 static inline int page_has_type(struct page *page)
 704 {
 705         return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
 706 }
 707
 708 #define PAGE_TYPE_OPS(uname, lname)                                     \
 709 static __always_inline int Page##uname(struct page *page)               \
 710 {                                                                       \
 711         return PageType(page, PG_##lname);                              \
 712 }                                                                       \
 713 static __always_inline void __SetPage##uname(struct page *page)         \
 714 {                                                                       \
 715         VM_BUG_ON_PAGE(!PageType(page, 0), page);                       \
 716         page->page_type &= ~PG_##lname;                                 \
 717 }                                                                       \
 718 static __always_inline void __ClearPage##uname(struct page *page)       \
 719 {                                                                       \
 720         VM_BUG_ON_PAGE(!Page##uname(page), page);                       \
 721         page->page_type |= PG_##lname;                                  \
 722 }
 723
 724 /*
 725  * PageBuddy() indicates that the page is free and in the buddy system
 726  * (see mm/page_alloc.c).
 727  */
 728 PAGE_TYPE_OPS(Buddy, buddy)
 729
 730 /*
 731  * PageOffline() indicates that the page is logically offline although the
 732  * containing section is online. (e.g. inflated in a balloon driver or
 733  * not onlined when onlining the section).
 734  * The content of these pages is effectively stale. Such pages should not
 735  * be touched (read/write/dump/save) except by their owner.
 736  *
 737  * If a driver wants to allow to offline unmovable PageOffline() pages without
 738  * putting them back to the buddy, it can do so via the memory notifier by
 739  * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
 740  * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
 741  * pages (now with a reference count of zero) are treated like free pages,
 742  * allowing the containing memory block to get offlined. A driver that
 743  * relies on this feature is aware that re-onlining the memory block will
 744  * require to re-set the pages PageOffline() and not giving them to the
 745  * buddy via online_page_callback_t.
 746  *
 747  * There are drivers that mark a page PageOffline() and expect there won't be
 748  * any further access to page content. PFN walkers that read content of random
 749  * pages should check PageOffline() and synchronize with such drivers using
 750  * page_offline_freeze()/page_offline_thaw().
 751  */
 752 PAGE_TYPE_OPS(Offline, offline)
 753
 754 extern void page_offline_freeze(void);
 755 extern void page_offline_thaw(void);
 756 extern void page_offline_begin(void);
 757 extern void page_offline_end(void);
 758
 759 /*
 760  * Marks pages in use as page tables.
 761  */
 762 PAGE_TYPE_OPS(Table, table)
 763
 764 /*
 765  * Marks guardpages used with debug_pagealloc.
 766  */
 767 PAGE_TYPE_OPS(Guard, guard)
 768
 769 extern bool is_free_buddy_page(struct page *page);
 770
 771 __PAGEFLAG(Isolated, isolated, PF_ANY);
 772
 773 /*
 774  * If network-based swap is enabled, sl*b must keep track of whether pages
 775  * were allocated from pfmemalloc reserves.
 776  */
 777 static inline int PageSlabPfmemalloc(struct page *page)
 778 {
 779         VM_BUG_ON_PAGE(!PageSlab(page), page);
 780         return PageActive(page);
 781 }
 782
 783 /*
 784  * A version of PageSlabPfmemalloc() for opportunistic checks where the page
 785  * might have been freed under us and not be a PageSlab anymore.
 786  */
 787 static inline int __PageSlabPfmemalloc(struct page *page)
 788 {
 789         return PageActive(page);
 790 }
 791
 792 static inline void SetPageSlabPfmemalloc(struct page *page)
 793 {
 794         VM_BUG_ON_PAGE(!PageSlab(page), page);
 795         SetPageActive(page);
 796 }
 797
 798 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 799 {
 800         VM_BUG_ON_PAGE(!PageSlab(page), page);
 801         __ClearPageActive(page);
 802 }
 803
 804 static inline void ClearPageSlabPfmemalloc(struct page *page)
 805 {
 806         VM_BUG_ON_PAGE(!PageSlab(page), page);
 807         ClearPageActive(page);
 808 }
 809
 810 #ifdef CONFIG_MMU
 811 #define __PG_MLOCKED            (1UL << PG_mlocked)
 812 #else
 813 #define __PG_MLOCKED            0
 814 #endif
 815
 816 /*
 817  * Flags checked when a page is freed.  Pages being freed should not have
 818  * these flags set.  If they are, there is a problem.
 819  */
 820 #define PAGE_FLAGS_CHECK_AT_FREE                                \
 821         (1UL << PG_lru          | 1UL << PG_locked      |       \
 822          1UL << PG_private      | 1UL << PG_private_2   |       \
 823          1UL << PG_writeback    | 1UL << PG_reserved    |       \
 824          1UL << PG_slab         | 1UL << PG_active      |       \
 825          1UL << PG_unevictable  | __PG_MLOCKED)
 826
 827 /*
 828  * Flags checked when a page is prepped for return by the page allocator.
 829  * Pages being prepped should not have these flags set.  If they are set,
 830  * there has been a kernel bug or struct page corruption.
 831  *
 832  * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 833  * alloc-free cycle to prevent from reusing the page.
 834  */
 835 #define PAGE_FLAGS_CHECK_AT_PREP        \
 836         (PAGEFLAGS_MASK & ~__PG_HWPOISON)
 837
 838 #define PAGE_FLAGS_PRIVATE                              \
 839         (1UL << PG_private | 1UL << PG_private_2)
 840 /**
 841  * page_has_private - Determine if page has private stuff
 842  * @page: The page to be checked
 843  *
 844  * Determine if a page has private stuff, indicating that release routines
 845  * should be invoked upon it.
 846  */
 847 static inline int page_has_private(struct page *page)
 848 {
 849         return !!(page->flags & PAGE_FLAGS_PRIVATE);
 850 }
 851
 852 #undef PF_ANY
 853 #undef PF_HEAD
 854 #undef PF_ONLY_HEAD
 855 #undef PF_NO_TAIL
 856 #undef PF_NO_COMPOUND
 857 #undef PF_SECOND
 858 #endif /* !__GENERATING_BOUNDS_H */
 859
 860 #endif  /* PAGE_FLAGS_H */