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 #ifdef CONFIG_PAGEFLAGS_EXTENDED
  90         PG_head,                /* A head page */
  91         PG_tail,                /* A tail page */
  92 #else
  93         PG_compound,            /* A compound page */
  94 #endif
  95         PG_swapcache,           /* Swap page: swp_entry_t in private */
  96         PG_mappedtodisk,        /* Has blocks allocated on-disk */
  97         PG_reclaim,             /* To be reclaimed asap */
  98         PG_swapbacked,          /* Page is backed by RAM/swap */
  99         PG_unevictable,         /* Page is "unevictable"  */
 100 #ifdef CONFIG_MMU
 101         PG_mlocked,             /* Page is vma mlocked */
 102 #endif
 103 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 104         PG_uncached,            /* Page has been mapped as uncached */
 105 #endif
 106 #ifdef CONFIG_MEMORY_FAILURE
 107         PG_hwpoison,            /* hardware poisoned page. Don't touch */
 108 #endif
 109 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 110         PG_compound_lock,
 111 #endif
 112 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 113         PG_young,
 114         PG_idle,
 115 #endif
 116         __NR_PAGEFLAGS,
 117
 118         /* Filesystems */
 119         PG_checked = PG_owner_priv_1,
 120
 121         /* Two page bits are conscripted by FS-Cache to maintain local caching
 122          * state.  These bits are set on pages belonging to the netfs's inodes
 123          * when those inodes are being locally cached.
 124          */
 125         PG_fscache = PG_private_2,      /* page backed by cache */
 126
 127         /* XEN */
 128         /* Pinned in Xen as a read-only pagetable page. */
 129         PG_pinned = PG_owner_priv_1,
 130         /* Pinned as part of domain save (see xen_mm_pin_all()). */
 131         PG_savepinned = PG_dirty,
 132         /* Has a grant mapping of another (foreign) domain's page. */
 133         PG_foreign = PG_owner_priv_1,
 134
 135         /* SLOB */
 136         PG_slob_free = PG_private,
 137 };
 138
 139 #ifndef __GENERATING_BOUNDS_H
 140
 141 /*
 142  * Macros to create function definitions for page flags
 143  */
 144 #define TESTPAGEFLAG(uname, lname)                                      \
 145 static inline int Page##uname(const struct page *page)                  \
 146                         { return test_bit(PG_##lname, &page->flags); }
 147
 148 #define SETPAGEFLAG(uname, lname)                                       \
 149 static inline void SetPage##uname(struct page *page)                    \
 150                         { set_bit(PG_##lname, &page->flags); }
 151
 152 #define CLEARPAGEFLAG(uname, lname)                                     \
 153 static inline void ClearPage##uname(struct page *page)                  \
 154                         { clear_bit(PG_##lname, &page->flags); }
 155
 156 #define __SETPAGEFLAG(uname, lname)                                     \
 157 static inline void __SetPage##uname(struct page *page)                  \
 158                         { __set_bit(PG_##lname, &page->flags); }
 159
 160 #define __CLEARPAGEFLAG(uname, lname)                                   \
 161 static inline void __ClearPage##uname(struct page *page)                \
 162                         { __clear_bit(PG_##lname, &page->flags); }
 163
 164 #define TESTSETFLAG(uname, lname)                                       \
 165 static inline int TestSetPage##uname(struct page *page)                 \
 166                 { return test_and_set_bit(PG_##lname, &page->flags); }
 167
 168 #define TESTCLEARFLAG(uname, lname)                                     \
 169 static inline int TestClearPage##uname(struct page *page)               \
 170                 { return test_and_clear_bit(PG_##lname, &page->flags); }
 171
 172 #define __TESTCLEARFLAG(uname, lname)                                   \
 173 static inline int __TestClearPage##uname(struct page *page)             \
 174                 { return __test_and_clear_bit(PG_##lname, &page->flags); }
 175
 176 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname)               \
 177         SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
 178
 179 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname)             \
 180         __SETPAGEFLAG(uname, lname)  __CLEARPAGEFLAG(uname, lname)
 181
 182 #define TESTSCFLAG(uname, lname)                                        \
 183         TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
 184
 185 #define TESTPAGEFLAG_FALSE(uname)                                       \
 186 static inline int Page##uname(const struct page *page) { return 0; }
 187
 188 #define SETPAGEFLAG_NOOP(uname)                                         \
 189 static inline void SetPage##uname(struct page *page) {  }
 190
 191 #define CLEARPAGEFLAG_NOOP(uname)                                       \
 192 static inline void ClearPage##uname(struct page *page) {  }
 193
 194 #define __CLEARPAGEFLAG_NOOP(uname)                                     \
 195 static inline void __ClearPage##uname(struct page *page) {  }
 196
 197 #define TESTSETFLAG_FALSE(uname)                                        \
 198 static inline int TestSetPage##uname(struct page *page) { return 0; }
 199
 200 #define TESTCLEARFLAG_FALSE(uname)                                      \
 201 static inline int TestClearPage##uname(struct page *page) { return 0; }
 202
 203 #define __TESTCLEARFLAG_FALSE(uname)                                    \
 204 static inline int __TestClearPage##uname(struct page *page) { return 0; }
 205
 206 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)                 \
 207         SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
 208
 209 #define TESTSCFLAG_FALSE(uname)                                         \
 210         TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 211
 212 struct page;    /* forward declaration */
 213
 214 TESTPAGEFLAG(Locked, locked)
 215 PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
 216 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
 217         __SETPAGEFLAG(Referenced, referenced)
 218 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
 219 PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
 220 PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
 221         TESTCLEARFLAG(Active, active)
 222 __PAGEFLAG(Slab, slab)
 223 PAGEFLAG(Checked, checked)              /* Used by some filesystems */
 224 PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned)     /* Xen */
 225 PAGEFLAG(SavePinned, savepinned);                       /* Xen */
 226 PAGEFLAG(Foreign, foreign);                             /* Xen */
 227 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
 228 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
 229         __SETPAGEFLAG(SwapBacked, swapbacked)
 230
 231 __PAGEFLAG(SlobFree, slob_free)
 232
 233 /*
 234  * Private page markings that may be used by the filesystem that owns the page
 235  * for its own purposes.
 236  * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 237  */
 238 PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
 239         __CLEARPAGEFLAG(Private, private)
 240 PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
 241 PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
 242
 243 /*
 244  * Only test-and-set exist for PG_writeback.  The unconditional operators are
 245  * risky: they bypass page accounting.
 246  */
 247 TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
 248 PAGEFLAG(MappedToDisk, mappedtodisk)
 249
 250 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 251 PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
 252 PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)
 253
 254 #ifdef CONFIG_HIGHMEM
 255 /*
 256  * Must use a macro here due to header dependency issues. page_zone() is not
 257  * available at this point.
 258  */
 259 #define PageHighMem(__p) is_highmem(page_zone(__p))
 260 #else
 261 PAGEFLAG_FALSE(HighMem)
 262 #endif
 263
 264 #ifdef CONFIG_SWAP
 265 PAGEFLAG(SwapCache, swapcache)
 266 #else
 267 PAGEFLAG_FALSE(SwapCache)
 268 #endif
 269
 270 PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
 271         TESTCLEARFLAG(Unevictable, unevictable)
 272
 273 #ifdef CONFIG_MMU
 274 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
 275         TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
 276 #else
 277 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
 278         TESTSCFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
 279 #endif
 280
 281 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 282 PAGEFLAG(Uncached, uncached)
 283 #else
 284 PAGEFLAG_FALSE(Uncached)
 285 #endif
 286
 287 #ifdef CONFIG_MEMORY_FAILURE
 288 PAGEFLAG(HWPoison, hwpoison)
 289 TESTSCFLAG(HWPoison, hwpoison)
 290 #define __PG_HWPOISON (1UL << PG_hwpoison)
 291 #else
 292 PAGEFLAG_FALSE(HWPoison)
 293 #define __PG_HWPOISON 0
 294 #endif
 295
 296 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 297 TESTPAGEFLAG(Young, young)
 298 SETPAGEFLAG(Young, young)
 299 TESTCLEARFLAG(Young, young)
 300 PAGEFLAG(Idle, idle)
 301 #endif
 302
 303 /*
 304  * On an anonymous page mapped into a user virtual memory area,
 305  * page->mapping points to its anon_vma, not to a struct address_space;
 306  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 307  *
 308  * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 309  * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
 310  * and then page->mapping points, not to an anon_vma, but to a private
 311  * structure which KSM associates with that merged page.  See ksm.h.
 312  *
 313  * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
 314  *
 315  * Please note that, confusingly, "page_mapping" refers to the inode
 316  * address_space which maps the page from disk; whereas "page_mapped"
 317  * refers to user virtual address space into which the page is mapped.
 318  */
 319 #define PAGE_MAPPING_ANON       1
 320 #define PAGE_MAPPING_KSM        2
 321 #define PAGE_MAPPING_FLAGS      (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
 322
 323 static inline int PageAnon(struct page *page)
 324 {
 325         return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 326 }
 327
 328 #ifdef CONFIG_KSM
 329 /*
 330  * A KSM page is one of those write-protected "shared pages" or "merged pages"
 331  * which KSM maps into multiple mms, wherever identical anonymous page content
 332  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 333  * anon_vma, but to that page's node of the stable tree.
 334  */
 335 static inline int PageKsm(struct page *page)
 336 {
 337         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 338                                 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 339 }
 340 #else
 341 TESTPAGEFLAG_FALSE(Ksm)
 342 #endif
 343
 344 u64 stable_page_flags(struct page *page);
 345
 346 static inline int PageUptodate(struct page *page)
 347 {
 348         int ret = test_bit(PG_uptodate, &(page)->flags);
 349
 350         /*
 351          * Must ensure that the data we read out of the page is loaded
 352          * _after_ we've loaded page->flags to check for PageUptodate.
 353          * We can skip the barrier if the page is not uptodate, because
 354          * we wouldn't be reading anything from it.
 355          *
 356          * See SetPageUptodate() for the other side of the story.
 357          */
 358         if (ret)
 359                 smp_rmb();
 360
 361         return ret;
 362 }
 363
 364 static inline void __SetPageUptodate(struct page *page)
 365 {
 366         smp_wmb();
 367         __set_bit(PG_uptodate, &(page)->flags);
 368 }
 369
 370 static inline void SetPageUptodate(struct page *page)
 371 {
 372         /*
 373          * Memory barrier must be issued before setting the PG_uptodate bit,
 374          * so that all previous stores issued in order to bring the page
 375          * uptodate are actually visible before PageUptodate becomes true.
 376          */
 377         smp_wmb();
 378         set_bit(PG_uptodate, &(page)->flags);
 379 }
 380
 381 CLEARPAGEFLAG(Uptodate, uptodate)
 382
 383 int test_clear_page_writeback(struct page *page);
 384 int __test_set_page_writeback(struct page *page, bool keep_write);
 385
 386 #define test_set_page_writeback(page)                   \
 387         __test_set_page_writeback(page, false)
 388 #define test_set_page_writeback_keepwrite(page) \
 389         __test_set_page_writeback(page, true)
 390
 391 static inline void set_page_writeback(struct page *page)
 392 {
 393         test_set_page_writeback(page);
 394 }
 395
 396 static inline void set_page_writeback_keepwrite(struct page *page)
 397 {
 398         test_set_page_writeback_keepwrite(page);
 399 }
 400
 401 #ifdef CONFIG_PAGEFLAGS_EXTENDED
 402 /*
 403  * System with lots of page flags available. This allows separate
 404  * flags for PageHead() and PageTail() checks of compound pages so that bit
 405  * tests can be used in performance sensitive paths. PageCompound is
 406  * generally not used in hot code paths except arch/powerpc/mm/init_64.c
 407  * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
 408  * and avoid handling those in real mode.
 409  */
 410 __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head)
 411 __PAGEFLAG(Tail, tail)
 412
 413 static inline int PageCompound(struct page *page)
 414 {
 415         return page->flags & ((1L << PG_head) | (1L << PG_tail));
 416
 417 }
 418 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 419 static inline void ClearPageCompound(struct page *page)
 420 {
 421         BUG_ON(!PageHead(page));
 422         ClearPageHead(page);
 423 }
 424 #endif
 425
 426 #define PG_head_mask ((1L << PG_head))
 427
 428 #else
 429 /*
 430  * Reduce page flag use as much as possible by overlapping
 431  * compound page flags with the flags used for page cache pages. Possible
 432  * because PageCompound is always set for compound pages and not for
 433  * pages on the LRU and/or pagecache.
 434  */
 435 TESTPAGEFLAG(Compound, compound)
 436 __SETPAGEFLAG(Head, compound)  __CLEARPAGEFLAG(Head, compound)
 437
 438 /*
 439  * PG_reclaim is used in combination with PG_compound to mark the
 440  * head and tail of a compound page. This saves one page flag
 441  * but makes it impossible to use compound pages for the page cache.
 442  * The PG_reclaim bit would have to be used for reclaim or readahead
 443  * if compound pages enter the page cache.
 444  *
 445  * PG_compound & PG_reclaim     => Tail page
 446  * PG_compound & ~PG_reclaim    => Head page
 447  */
 448 #define PG_head_mask ((1L << PG_compound))
 449 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
 450
 451 static inline int PageHead(struct page *page)
 452 {
 453         return ((page->flags & PG_head_tail_mask) == PG_head_mask);
 454 }
 455
 456 static inline int PageTail(struct page *page)
 457 {
 458         return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
 459 }
 460
 461 static inline void __SetPageTail(struct page *page)
 462 {
 463         page->flags |= PG_head_tail_mask;
 464 }
 465
 466 static inline void __ClearPageTail(struct page *page)
 467 {
 468         page->flags &= ~PG_head_tail_mask;
 469 }
 470
 471 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 472 static inline void ClearPageCompound(struct page *page)
 473 {
 474         BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound));
 475         clear_bit(PG_compound, &page->flags);
 476 }
 477 #endif
 478
 479 #endif /* !PAGEFLAGS_EXTENDED */
 480
 481 #ifdef CONFIG_HUGETLB_PAGE
 482 int PageHuge(struct page *page);
 483 int PageHeadHuge(struct page *page);
 484 bool page_huge_active(struct page *page);
 485 #else
 486 TESTPAGEFLAG_FALSE(Huge)
 487 TESTPAGEFLAG_FALSE(HeadHuge)
 488
 489 static inline bool page_huge_active(struct page *page)
 490 {
 491         return 0;
 492 }
 493 #endif
 494
 495
 496 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 497 /*
 498  * PageHuge() only returns true for hugetlbfs pages, but not for
 499  * normal or transparent huge pages.
 500  *
 501  * PageTransHuge() returns true for both transparent huge and
 502  * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 503  * called only in the core VM paths where hugetlbfs pages can't exist.
 504  */
 505 static inline int PageTransHuge(struct page *page)
 506 {
 507         VM_BUG_ON_PAGE(PageTail(page), page);
 508         return PageHead(page);
 509 }
 510
 511 /*
 512  * PageTransCompound returns true for both transparent huge pages
 513  * and hugetlbfs pages, so it should only be called when it's known
 514  * that hugetlbfs pages aren't involved.
 515  */
 516 static inline int PageTransCompound(struct page *page)
 517 {
 518         return PageCompound(page);
 519 }
 520
 521 /*
 522  * PageTransTail returns true for both transparent huge pages
 523  * and hugetlbfs pages, so it should only be called when it's known
 524  * that hugetlbfs pages aren't involved.
 525  */
 526 static inline int PageTransTail(struct page *page)
 527 {
 528         return PageTail(page);
 529 }
 530
 531 #else
 532
 533 static inline int PageTransHuge(struct page *page)
 534 {
 535         return 0;
 536 }
 537
 538 static inline int PageTransCompound(struct page *page)
 539 {
 540         return 0;
 541 }
 542
 543 static inline int PageTransTail(struct page *page)
 544 {
 545         return 0;
 546 }
 547 #endif
 548
 549 /*
 550  * PageBuddy() indicate that the page is free and in the buddy system
 551  * (see mm/page_alloc.c).
 552  *
 553  * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
 554  * -2 so that an underflow of the page_mapcount() won't be mistaken
 555  * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
 556  * efficiently by most CPU architectures.
 557  */
 558 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
 559
 560 static inline int PageBuddy(struct page *page)
 561 {
 562         return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
 563 }
 564
 565 static inline void __SetPageBuddy(struct page *page)
 566 {
 567         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 568         atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 569 }
 570
 571 static inline void __ClearPageBuddy(struct page *page)
 572 {
 573         VM_BUG_ON_PAGE(!PageBuddy(page), page);
 574         atomic_set(&page->_mapcount, -1);
 575 }
 576
 577 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
 578
 579 static inline int PageBalloon(struct page *page)
 580 {
 581         return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
 582 }
 583
 584 static inline void __SetPageBalloon(struct page *page)
 585 {
 586         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 587         atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
 588 }
 589
 590 static inline void __ClearPageBalloon(struct page *page)
 591 {
 592         VM_BUG_ON_PAGE(!PageBalloon(page), page);
 593         atomic_set(&page->_mapcount, -1);
 594 }
 595
 596 /*
 597  * If network-based swap is enabled, sl*b must keep track of whether pages
 598  * were allocated from pfmemalloc reserves.
 599  */
 600 static inline int PageSlabPfmemalloc(struct page *page)
 601 {
 602         VM_BUG_ON_PAGE(!PageSlab(page), page);
 603         return PageActive(page);
 604 }
 605
 606 static inline void SetPageSlabPfmemalloc(struct page *page)
 607 {
 608         VM_BUG_ON_PAGE(!PageSlab(page), page);
 609         SetPageActive(page);
 610 }
 611
 612 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 613 {
 614         VM_BUG_ON_PAGE(!PageSlab(page), page);
 615         __ClearPageActive(page);
 616 }
 617
 618 static inline void ClearPageSlabPfmemalloc(struct page *page)
 619 {
 620         VM_BUG_ON_PAGE(!PageSlab(page), page);
 621         ClearPageActive(page);
 622 }
 623
 624 #ifdef CONFIG_MMU
 625 #define __PG_MLOCKED            (1 << PG_mlocked)
 626 #else
 627 #define __PG_MLOCKED            0
 628 #endif
 629
 630 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 631 #define __PG_COMPOUND_LOCK              (1 << PG_compound_lock)
 632 #else
 633 #define __PG_COMPOUND_LOCK              0
 634 #endif
 635
 636 /*
 637  * Flags checked when a page is freed.  Pages being freed should not have
 638  * these flags set.  It they are, there is a problem.
 639  */
 640 #define PAGE_FLAGS_CHECK_AT_FREE \
 641         (1 << PG_lru     | 1 << PG_locked    | \
 642          1 << PG_private | 1 << PG_private_2 | \
 643          1 << PG_writeback | 1 << PG_reserved | \
 644          1 << PG_slab    | 1 << PG_swapcache | 1 << PG_active | \
 645          1 << PG_unevictable | __PG_MLOCKED | \
 646          __PG_COMPOUND_LOCK)
 647
 648 /*
 649  * Flags checked when a page is prepped for return by the page allocator.
 650  * Pages being prepped should not have these flags set.  It they are set,
 651  * there has been a kernel bug or struct page corruption.
 652  *
 653  * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 654  * alloc-free cycle to prevent from reusing the page.
 655  */
 656 #define PAGE_FLAGS_CHECK_AT_PREP        \
 657         (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
 658
 659 #define PAGE_FLAGS_PRIVATE                              \
 660         (1 << PG_private | 1 << PG_private_2)
 661 /**
 662  * page_has_private - Determine if page has private stuff
 663  * @page: The page to be checked
 664  *
 665  * Determine if a page has private stuff, indicating that release routines
 666  * should be invoked upon it.
 667  */
 668 static inline int page_has_private(struct page *page)
 669 {
 670         return !!(page->flags & PAGE_FLAGS_PRIVATE);
 671 }
 672
 673 #endif /* !__GENERATING_BOUNDS_H */
 674
 675 #endif  /* PAGE_FLAGS_H */