include/linux/page-flags.h

   1 /*
   2  * Macros for manipulating and testing page->flags
   3  */
   4
   5 #ifndef PAGE_FLAGS_H
   6 #define PAGE_FLAGS_H
   7
   8 #include <linux/types.h>
   9 #include <linux/bug.h>
  10 #include <linux/mmdebug.h>
  11 #ifndef __GENERATING_BOUNDS_H
  12 #include <linux/mm_types.h>
  13 #include <generated/bounds.h>
  14 #endif /* !__GENERATING_BOUNDS_H */
  15
  16 /*
  17  * Various page->flags bits:
  18  *
  19  * PG_reserved is set for special pages, which can never be swapped out. Some
  20  * of them might not even exist (eg empty_bad_page)...
  21  *
  22  * The PG_private bitflag is set on pagecache pages if they contain filesystem
  23  * specific data (which is normally at page->private). It can be used by
  24  * private allocations for its own usage.
  25  *
  26  * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
  27  * and cleared when writeback _starts_ or when read _completes_. PG_writeback
  28  * is set before writeback starts and cleared when it finishes.
  29  *
  30  * PG_locked also pins a page in pagecache, and blocks truncation of the file
  31  * while it is held.
  32  *
  33  * page_waitqueue(page) is a wait queue of all tasks waiting for the page
  34  * to become unlocked.
  35  *
  36  * PG_uptodate tells whether the page's contents is valid.  When a read
  37  * completes, the page becomes uptodate, unless a disk I/O error happened.
  38  *
  39  * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
  40  * file-backed pagecache (see mm/vmscan.c).
  41  *
  42  * PG_error is set to indicate that an I/O error occurred on this page.
  43  *
  44  * PG_arch_1 is an architecture specific page state bit.  The generic code
  45  * guarantees that this bit is cleared for a page when it first is entered into
  46  * the page cache.
  47  *
  48  * PG_highmem pages are not permanently mapped into the kernel virtual address
  49  * space, they need to be kmapped separately for doing IO on the pages.  The
  50  * struct page (these bits with information) are always mapped into kernel
  51  * address space...
  52  *
  53  * PG_hwpoison indicates that a page got corrupted in hardware and contains
  54  * data with incorrect ECC bits that triggered a machine check. Accessing is
  55  * not safe since it may cause another machine check. Don't touch!
  56  */
  57
  58 /*
  59  * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
  60  * locked- and dirty-page accounting.
  61  *
  62  * The page flags field is split into two parts, the main flags area
  63  * which extends from the low bits upwards, and the fields area which
  64  * extends from the high bits downwards.
  65  *
  66  *  | FIELD | ... | FLAGS |
  67  *  N-1           ^       0
  68  *               (NR_PAGEFLAGS)
  69  *
  70  * The fields area is reserved for fields mapping zone, node (for NUMA) and
  71  * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
  72  * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
  73  */
  74 enum pageflags {
  75         PG_locked,              /* Page is locked. Don't touch. */
  76         PG_error,
  77         PG_referenced,
  78         PG_uptodate,
  79         PG_dirty,
  80         PG_lru,
  81         PG_active,
  82         PG_slab,
  83         PG_owner_priv_1,        /* Owner use. If pagecache, fs may use*/
  84         PG_arch_1,
  85         PG_reserved,
  86         PG_private,             /* If pagecache, has fs-private data */
  87         PG_private_2,           /* If pagecache, has fs aux data */
  88         PG_writeback,           /* Page is under writeback */
  89         PG_head,                /* A head page */
  90         PG_swapcache,           /* Swap page: swp_entry_t in private */
  91         PG_mappedtodisk,        /* Has blocks allocated on-disk */
  92         PG_reclaim,             /* To be reclaimed asap */
  93         PG_swapbacked,          /* Page is backed by RAM/swap */
  94         PG_unevictable,         /* Page is "unevictable"  */
  95 #ifdef CONFIG_MMU
  96         PG_mlocked,             /* Page is vma mlocked */
  97 #endif
  98 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
  99         PG_uncached,            /* Page has been mapped as uncached */
 100 #endif
 101 #ifdef CONFIG_MEMORY_FAILURE
 102         PG_hwpoison,            /* hardware poisoned page. Don't touch */
 103 #endif
 104 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 105         PG_compound_lock,
 106 #endif
 107 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 108         PG_young,
 109         PG_idle,
 110 #endif
 111         __NR_PAGEFLAGS,
 112
 113         /* Filesystems */
 114         PG_checked = PG_owner_priv_1,
 115
 116         /* Two page bits are conscripted by FS-Cache to maintain local caching
 117          * state.  These bits are set on pages belonging to the netfs's inodes
 118          * when those inodes are being locally cached.
 119          */
 120         PG_fscache = PG_private_2,      /* page backed by cache */
 121
 122         /* XEN */
 123         /* Pinned in Xen as a read-only pagetable page. */
 124         PG_pinned = PG_owner_priv_1,
 125         /* Pinned as part of domain save (see xen_mm_pin_all()). */
 126         PG_savepinned = PG_dirty,
 127         /* Has a grant mapping of another (foreign) domain's page. */
 128         PG_foreign = PG_owner_priv_1,
 129
 130         /* SLOB */
 131         PG_slob_free = PG_private,
 132 };
 133
 134 #ifndef __GENERATING_BOUNDS_H
 135
 136 struct page;    /* forward declaration */
 137
 138 static inline struct page *compound_head(struct page *page)
 139 {
 140         unsigned long head = READ_ONCE(page->compound_head);
 141
 142         if (unlikely(head & 1))
 143                 return (struct page *) (head - 1);
 144         return page;
 145 }
 146
 147 static inline int PageTail(struct page *page)
 148 {
 149         return READ_ONCE(page->compound_head) & 1;
 150 }
 151
 152 static inline int PageCompound(struct page *page)
 153 {
 154         return test_bit(PG_head, &page->flags) || PageTail(page);
 155 }
 156
 157 /*
 158  * Page flags policies wrt compound pages
 159  *
 160  * PF_ANY:
 161  *     the page flag is relevant for small, head and tail pages.
 162  *
 163  * PF_HEAD:
 164  *     for compound page all operations related to the page flag applied to
 165  *     head page.
 166  *
 167  * PF_NO_TAIL:
 168  *     modifications of the page flag must be done on small or head pages,
 169  *     checks can be done on tail pages too.
 170  *
 171  * PF_NO_COMPOUND:
 172  *     the page flag is not relevant for compound pages.
 173  */
 174 #define PF_ANY(page, enforce)   page
 175 #define PF_HEAD(page, enforce)  compound_head(page)
 176 #define PF_NO_TAIL(page, enforce) ({                                    \
 177                 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);     \
 178                 compound_head(page);})
 179 #define PF_NO_COMPOUND(page, enforce) ({                                        \
 180                 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
 181                 page;})
 182
 183 /*
 184  * Macros to create function definitions for page flags
 185  */
 186 #define TESTPAGEFLAG(uname, lname, policy)                              \
 187 static inline int Page##uname(struct page *page)                        \
 188         { return test_bit(PG_##lname, &policy(page, 0)->flags); }
 189
 190 #define SETPAGEFLAG(uname, lname, policy)                               \
 191 static inline void SetPage##uname(struct page *page)                    \
 192         { set_bit(PG_##lname, &policy(page, 1)->flags); }
 193
 194 #define CLEARPAGEFLAG(uname, lname, policy)                             \
 195 static inline void ClearPage##uname(struct page *page)                  \
 196         { clear_bit(PG_##lname, &policy(page, 1)->flags); }
 197
 198 #define __SETPAGEFLAG(uname, lname, policy)                             \
 199 static inline void __SetPage##uname(struct page *page)                  \
 200         { __set_bit(PG_##lname, &policy(page, 1)->flags); }
 201
 202 #define __CLEARPAGEFLAG(uname, lname, policy)                           \
 203 static inline void __ClearPage##uname(struct page *page)                \
 204         { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
 205
 206 #define TESTSETFLAG(uname, lname, policy)                               \
 207 static inline int TestSetPage##uname(struct page *page)                 \
 208         { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
 209
 210 #define TESTCLEARFLAG(uname, lname, policy)                             \
 211 static inline int TestClearPage##uname(struct page *page)               \
 212         { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 213
 214 #define __TESTCLEARFLAG(uname, lname, policy)                           \
 215 static inline int __TestClearPage##uname(struct page *page)             \
 216         { return __test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 217
 218 #define PAGEFLAG(uname, lname, policy)                                  \
 219         TESTPAGEFLAG(uname, lname, policy)                              \
 220         SETPAGEFLAG(uname, lname, policy)                               \
 221         CLEARPAGEFLAG(uname, lname, policy)
 222
 223 #define __PAGEFLAG(uname, lname, policy)                                \
 224         TESTPAGEFLAG(uname, lname, policy)                              \
 225         __SETPAGEFLAG(uname, lname, policy)                             \
 226         __CLEARPAGEFLAG(uname, lname, policy)
 227
 228 #define TESTSCFLAG(uname, lname, policy)                                \
 229         TESTSETFLAG(uname, lname, policy)                               \
 230         TESTCLEARFLAG(uname, lname, policy)
 231
 232 #define TESTPAGEFLAG_FALSE(uname)                                       \
 233 static inline int Page##uname(const struct page *page) { return 0; }
 234
 235 #define SETPAGEFLAG_NOOP(uname)                                         \
 236 static inline void SetPage##uname(struct page *page) {  }
 237
 238 #define CLEARPAGEFLAG_NOOP(uname)                                       \
 239 static inline void ClearPage##uname(struct page *page) {  }
 240
 241 #define __CLEARPAGEFLAG_NOOP(uname)                                     \
 242 static inline void __ClearPage##uname(struct page *page) {  }
 243
 244 #define TESTSETFLAG_FALSE(uname)                                        \
 245 static inline int TestSetPage##uname(struct page *page) { return 0; }
 246
 247 #define TESTCLEARFLAG_FALSE(uname)                                      \
 248 static inline int TestClearPage##uname(struct page *page) { return 0; }
 249
 250 #define __TESTCLEARFLAG_FALSE(uname)                                    \
 251 static inline int __TestClearPage##uname(struct page *page) { return 0; }
 252
 253 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)                 \
 254         SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
 255
 256 #define TESTSCFLAG_FALSE(uname)                                         \
 257         TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 258
 259 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 260 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 261 PAGEFLAG(Referenced, referenced, PF_ANY) TESTCLEARFLAG(Referenced, referenced, PF_ANY)
 262         __SETPAGEFLAG(Referenced, referenced, PF_ANY)
 263 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
 264         __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
 265 PAGEFLAG(LRU, lru, PF_ANY) __CLEARPAGEFLAG(LRU, lru, PF_ANY)
 266 PAGEFLAG(Active, active, PF_ANY) __CLEARPAGEFLAG(Active, active, PF_ANY)
 267         TESTCLEARFLAG(Active, active, PF_ANY)
 268 __PAGEFLAG(Slab, slab, PF_ANY)
 269 PAGEFLAG(Checked, checked, PF_NO_COMPOUND)         /* Used by some filesystems */
 270 PAGEFLAG(Pinned, pinned, PF_ANY) TESTSCFLAG(Pinned, pinned, PF_ANY)     /* Xen */
 271 PAGEFLAG(SavePinned, savepinned, PF_ANY);                       /* Xen */
 272 PAGEFLAG(Foreign, foreign, PF_ANY);                             /* Xen */
 273 PAGEFLAG(Reserved, reserved, PF_ANY) __CLEARPAGEFLAG(Reserved, reserved, PF_ANY)
 274 PAGEFLAG(SwapBacked, swapbacked, PF_ANY)
 275         __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_ANY)
 276         __SETPAGEFLAG(SwapBacked, swapbacked, PF_ANY)
 277
 278 __PAGEFLAG(SlobFree, slob_free, PF_ANY)
 279
 280 /*
 281  * Private page markings that may be used by the filesystem that owns the page
 282  * for its own purposes.
 283  * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 284  */
 285 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
 286         __CLEARPAGEFLAG(Private, private, PF_ANY)
 287 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
 288 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 289         TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 290
 291 /*
 292  * Only test-and-set exist for PG_writeback.  The unconditional operators are
 293  * risky: they bypass page accounting.
 294  */
 295 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
 296         TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
 297 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)
 298
 299 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 300 PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
 301         TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
 302 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 303         TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 304
 305 #ifdef CONFIG_HIGHMEM
 306 /*
 307  * Must use a macro here due to header dependency issues. page_zone() is not
 308  * available at this point.
 309  */
 310 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
 311 #else
 312 PAGEFLAG_FALSE(HighMem)
 313 #endif
 314
 315 #ifdef CONFIG_SWAP
 316 PAGEFLAG(SwapCache, swapcache, PF_ANY)
 317 #else
 318 PAGEFLAG_FALSE(SwapCache)
 319 #endif
 320
 321 PAGEFLAG(Unevictable, unevictable, PF_ANY)
 322         __CLEARPAGEFLAG(Unevictable, unevictable, PF_ANY)
 323         TESTCLEARFLAG(Unevictable, unevictable, PF_ANY)
 324
 325 #ifdef CONFIG_MMU
 326 PAGEFLAG(Mlocked, mlocked, PF_ANY) __CLEARPAGEFLAG(Mlocked, mlocked, PF_ANY)
 327         TESTSCFLAG(Mlocked, mlocked, PF_ANY) __TESTCLEARFLAG(Mlocked, mlocked, PF_ANY)
 328 #else
 329 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
 330         TESTSCFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
 331 #endif
 332
 333 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 334 PAGEFLAG(Uncached, uncached, PF_ANY)
 335 #else
 336 PAGEFLAG_FALSE(Uncached)
 337 #endif
 338
 339 #ifdef CONFIG_MEMORY_FAILURE
 340 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 341 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 342 #define __PG_HWPOISON (1UL << PG_hwpoison)
 343 #else
 344 PAGEFLAG_FALSE(HWPoison)
 345 #define __PG_HWPOISON 0
 346 #endif
 347
 348 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 349 TESTPAGEFLAG(Young, young, PF_ANY)
 350 SETPAGEFLAG(Young, young, PF_ANY)
 351 TESTCLEARFLAG(Young, young, PF_ANY)
 352 PAGEFLAG(Idle, idle, PF_ANY)
 353 #endif
 354
 355 /*
 356  * On an anonymous page mapped into a user virtual memory area,
 357  * page->mapping points to its anon_vma, not to a struct address_space;
 358  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 359  *
 360  * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 361  * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
 362  * and then page->mapping points, not to an anon_vma, but to a private
 363  * structure which KSM associates with that merged page.  See ksm.h.
 364  *
 365  * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
 366  *
 367  * Please note that, confusingly, "page_mapping" refers to the inode
 368  * address_space which maps the page from disk; whereas "page_mapped"
 369  * refers to user virtual address space into which the page is mapped.
 370  */
 371 #define PAGE_MAPPING_ANON       1
 372 #define PAGE_MAPPING_KSM        2
 373 #define PAGE_MAPPING_FLAGS      (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
 374
 375 static inline int PageAnon(struct page *page)
 376 {
 377         return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 378 }
 379
 380 #ifdef CONFIG_KSM
 381 /*
 382  * A KSM page is one of those write-protected "shared pages" or "merged pages"
 383  * which KSM maps into multiple mms, wherever identical anonymous page content
 384  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 385  * anon_vma, but to that page's node of the stable tree.
 386  */
 387 static inline int PageKsm(struct page *page)
 388 {
 389         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 390                                 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 391 }
 392 #else
 393 TESTPAGEFLAG_FALSE(Ksm)
 394 #endif
 395
 396 u64 stable_page_flags(struct page *page);
 397
 398 static inline int PageUptodate(struct page *page)
 399 {
 400         int ret = test_bit(PG_uptodate, &(page)->flags);
 401
 402         /*
 403          * Must ensure that the data we read out of the page is loaded
 404          * _after_ we've loaded page->flags to check for PageUptodate.
 405          * We can skip the barrier if the page is not uptodate, because
 406          * we wouldn't be reading anything from it.
 407          *
 408          * See SetPageUptodate() for the other side of the story.
 409          */
 410         if (ret)
 411                 smp_rmb();
 412
 413         return ret;
 414 }
 415
 416 static inline void __SetPageUptodate(struct page *page)
 417 {
 418         smp_wmb();
 419         __set_bit(PG_uptodate, &page->flags);
 420 }
 421
 422 static inline void SetPageUptodate(struct page *page)
 423 {
 424         /*
 425          * Memory barrier must be issued before setting the PG_uptodate bit,
 426          * so that all previous stores issued in order to bring the page
 427          * uptodate are actually visible before PageUptodate becomes true.
 428          */
 429         smp_wmb();
 430         set_bit(PG_uptodate, &page->flags);
 431 }
 432
 433 CLEARPAGEFLAG(Uptodate, uptodate, PF_ANY)
 434
 435 int test_clear_page_writeback(struct page *page);
 436 int __test_set_page_writeback(struct page *page, bool keep_write);
 437
 438 #define test_set_page_writeback(page)                   \
 439         __test_set_page_writeback(page, false)
 440 #define test_set_page_writeback_keepwrite(page) \
 441         __test_set_page_writeback(page, true)
 442
 443 static inline void set_page_writeback(struct page *page)
 444 {
 445         test_set_page_writeback(page);
 446 }
 447
 448 static inline void set_page_writeback_keepwrite(struct page *page)
 449 {
 450         test_set_page_writeback_keepwrite(page);
 451 }
 452
 453 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
 454
 455 static inline void set_compound_head(struct page *page, struct page *head)
 456 {
 457         WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
 458 }
 459
 460 static inline void clear_compound_head(struct page *page)
 461 {
 462         WRITE_ONCE(page->compound_head, 0);
 463 }
 464
 465 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 466 static inline void ClearPageCompound(struct page *page)
 467 {
 468         BUG_ON(!PageHead(page));
 469         ClearPageHead(page);
 470 }
 471 #endif
 472
 473 #define PG_head_mask ((1L << PG_head))
 474
 475 #ifdef CONFIG_HUGETLB_PAGE
 476 int PageHuge(struct page *page);
 477 int PageHeadHuge(struct page *page);
 478 bool page_huge_active(struct page *page);
 479 #else
 480 TESTPAGEFLAG_FALSE(Huge)
 481 TESTPAGEFLAG_FALSE(HeadHuge)
 482
 483 static inline bool page_huge_active(struct page *page)
 484 {
 485         return 0;
 486 }
 487 #endif
 488
 489
 490 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 491 /*
 492  * PageHuge() only returns true for hugetlbfs pages, but not for
 493  * normal or transparent huge pages.
 494  *
 495  * PageTransHuge() returns true for both transparent huge and
 496  * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 497  * called only in the core VM paths where hugetlbfs pages can't exist.
 498  */
 499 static inline int PageTransHuge(struct page *page)
 500 {
 501         VM_BUG_ON_PAGE(PageTail(page), page);
 502         return PageHead(page);
 503 }
 504
 505 /*
 506  * PageTransCompound returns true for both transparent huge pages
 507  * and hugetlbfs pages, so it should only be called when it's known
 508  * that hugetlbfs pages aren't involved.
 509  */
 510 static inline int PageTransCompound(struct page *page)
 511 {
 512         return PageCompound(page);
 513 }
 514
 515 /*
 516  * PageTransTail returns true for both transparent huge pages
 517  * and hugetlbfs pages, so it should only be called when it's known
 518  * that hugetlbfs pages aren't involved.
 519  */
 520 static inline int PageTransTail(struct page *page)
 521 {
 522         return PageTail(page);
 523 }
 524
 525 #else
 526 TESTPAGEFLAG_FALSE(TransHuge)
 527 TESTPAGEFLAG_FALSE(TransCompound)
 528 TESTPAGEFLAG_FALSE(TransTail)
 529 #endif
 530
 531 /*
 532  * PageBuddy() indicate that the page is free and in the buddy system
 533  * (see mm/page_alloc.c).
 534  *
 535  * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
 536  * -2 so that an underflow of the page_mapcount() won't be mistaken
 537  * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
 538  * efficiently by most CPU architectures.
 539  */
 540 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
 541
 542 static inline int PageBuddy(struct page *page)
 543 {
 544         return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
 545 }
 546
 547 static inline void __SetPageBuddy(struct page *page)
 548 {
 549         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 550         atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 551 }
 552
 553 static inline void __ClearPageBuddy(struct page *page)
 554 {
 555         VM_BUG_ON_PAGE(!PageBuddy(page), page);
 556         atomic_set(&page->_mapcount, -1);
 557 }
 558
 559 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
 560
 561 static inline int PageBalloon(struct page *page)
 562 {
 563         return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
 564 }
 565
 566 static inline void __SetPageBalloon(struct page *page)
 567 {
 568         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 569         atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
 570 }
 571
 572 static inline void __ClearPageBalloon(struct page *page)
 573 {
 574         VM_BUG_ON_PAGE(!PageBalloon(page), page);
 575         atomic_set(&page->_mapcount, -1);
 576 }
 577
 578 /*
 579  * If network-based swap is enabled, sl*b must keep track of whether pages
 580  * were allocated from pfmemalloc reserves.
 581  */
 582 static inline int PageSlabPfmemalloc(struct page *page)
 583 {
 584         VM_BUG_ON_PAGE(!PageSlab(page), page);
 585         return PageActive(page);
 586 }
 587
 588 static inline void SetPageSlabPfmemalloc(struct page *page)
 589 {
 590         VM_BUG_ON_PAGE(!PageSlab(page), page);
 591         SetPageActive(page);
 592 }
 593
 594 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 595 {
 596         VM_BUG_ON_PAGE(!PageSlab(page), page);
 597         __ClearPageActive(page);
 598 }
 599
 600 static inline void ClearPageSlabPfmemalloc(struct page *page)
 601 {
 602         VM_BUG_ON_PAGE(!PageSlab(page), page);
 603         ClearPageActive(page);
 604 }
 605
 606 #ifdef CONFIG_MMU
 607 #define __PG_MLOCKED            (1 << PG_mlocked)
 608 #else
 609 #define __PG_MLOCKED            0
 610 #endif
 611
 612 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 613 #define __PG_COMPOUND_LOCK              (1 << PG_compound_lock)
 614 #else
 615 #define __PG_COMPOUND_LOCK              0
 616 #endif
 617
 618 /*
 619  * Flags checked when a page is freed.  Pages being freed should not have
 620  * these flags set.  It they are, there is a problem.
 621  */
 622 #define PAGE_FLAGS_CHECK_AT_FREE \
 623         (1 << PG_lru     | 1 << PG_locked    | \
 624          1 << PG_private | 1 << PG_private_2 | \
 625          1 << PG_writeback | 1 << PG_reserved | \
 626          1 << PG_slab    | 1 << PG_swapcache | 1 << PG_active | \
 627          1 << PG_unevictable | __PG_MLOCKED | \
 628          __PG_COMPOUND_LOCK)
 629
 630 /*
 631  * Flags checked when a page is prepped for return by the page allocator.
 632  * Pages being prepped should not have these flags set.  It they are set,
 633  * there has been a kernel bug or struct page corruption.
 634  *
 635  * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 636  * alloc-free cycle to prevent from reusing the page.
 637  */
 638 #define PAGE_FLAGS_CHECK_AT_PREP        \
 639         (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
 640
 641 #define PAGE_FLAGS_PRIVATE                              \
 642         (1 << PG_private | 1 << PG_private_2)
 643 /**
 644  * page_has_private - Determine if page has private stuff
 645  * @page: The page to be checked
 646  *
 647  * Determine if a page has private stuff, indicating that release routines
 648  * should be invoked upon it.
 649  */
 650 static inline int page_has_private(struct page *page)
 651 {
 652         return !!(page->flags & PAGE_FLAGS_PRIVATE);
 653 }
 654
 655 #undef PF_ANY
 656 #undef PF_HEAD
 657 #undef PF_NO_TAIL
 658 #undef PF_NO_COMPOUND
 659 #endif /* !__GENERATING_BOUNDS_H */
 660
 661 #endif  /* PAGE_FLAGS_H */