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 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 105         PG_young,
 106         PG_idle,
 107 #endif
 108         __NR_PAGEFLAGS,
 109
 110         /* Filesystems */
 111         PG_checked = PG_owner_priv_1,
 112
 113         /* Two page bits are conscripted by FS-Cache to maintain local caching
 114          * state.  These bits are set on pages belonging to the netfs's inodes
 115          * when those inodes are being locally cached.
 116          */
 117         PG_fscache = PG_private_2,      /* page backed by cache */
 118
 119         /* XEN */
 120         /* Pinned in Xen as a read-only pagetable page. */
 121         PG_pinned = PG_owner_priv_1,
 122         /* Pinned as part of domain save (see xen_mm_pin_all()). */
 123         PG_savepinned = PG_dirty,
 124         /* Has a grant mapping of another (foreign) domain's page. */
 125         PG_foreign = PG_owner_priv_1,
 126
 127         /* SLOB */
 128         PG_slob_free = PG_private,
 129
 130         /* Compound pages. Stored in first tail page's flags */
 131         PG_double_map = PG_private_2,
 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 __always_inline int PageTail(struct page *page)
 148 {
 149         return READ_ONCE(page->compound_head) & 1;
 150 }
 151
 152 static __always_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 __always_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 __always_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 __always_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 __always_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 __always_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 __always_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 __always_inline int TestClearPage##uname(struct page *page)      \
 212         { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 213
 214 #define PAGEFLAG(uname, lname, policy)                                  \
 215         TESTPAGEFLAG(uname, lname, policy)                              \
 216         SETPAGEFLAG(uname, lname, policy)                               \
 217         CLEARPAGEFLAG(uname, lname, policy)
 218
 219 #define __PAGEFLAG(uname, lname, policy)                                \
 220         TESTPAGEFLAG(uname, lname, policy)                              \
 221         __SETPAGEFLAG(uname, lname, policy)                             \
 222         __CLEARPAGEFLAG(uname, lname, policy)
 223
 224 #define TESTSCFLAG(uname, lname, policy)                                \
 225         TESTSETFLAG(uname, lname, policy)                               \
 226         TESTCLEARFLAG(uname, lname, policy)
 227
 228 #define TESTPAGEFLAG_FALSE(uname)                                       \
 229 static inline int Page##uname(const struct page *page) { return 0; }
 230
 231 #define SETPAGEFLAG_NOOP(uname)                                         \
 232 static inline void SetPage##uname(struct page *page) {  }
 233
 234 #define CLEARPAGEFLAG_NOOP(uname)                                       \
 235 static inline void ClearPage##uname(struct page *page) {  }
 236
 237 #define __CLEARPAGEFLAG_NOOP(uname)                                     \
 238 static inline void __ClearPage##uname(struct page *page) {  }
 239
 240 #define TESTSETFLAG_FALSE(uname)                                        \
 241 static inline int TestSetPage##uname(struct page *page) { return 0; }
 242
 243 #define TESTCLEARFLAG_FALSE(uname)                                      \
 244 static inline int TestClearPage##uname(struct page *page) { return 0; }
 245
 246 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)                 \
 247         SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
 248
 249 #define TESTSCFLAG_FALSE(uname)                                         \
 250         TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 251
 252 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 253 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 254 PAGEFLAG(Referenced, referenced, PF_HEAD)
 255         TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
 256         __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
 257 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
 258         __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
 259 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
 260 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
 261         TESTCLEARFLAG(Active, active, PF_HEAD)
 262 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
 263 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
 264 PAGEFLAG(Checked, checked, PF_NO_COMPOUND)         /* Used by some filesystems */
 265
 266 /* Xen */
 267 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
 268         TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
 269 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
 270 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
 271
 272 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 273         __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 274 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 275         __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 276         __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 277
 278 /*
 279  * Private page markings that may be used by the filesystem that owns the page
 280  * for its own purposes.
 281  * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 282  */
 283 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
 284         __CLEARPAGEFLAG(Private, private, PF_ANY)
 285 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
 286 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 287         TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 288
 289 /*
 290  * Only test-and-set exist for PG_writeback.  The unconditional operators are
 291  * risky: they bypass page accounting.
 292  */
 293 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
 294         TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
 295 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)
 296
 297 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 298 PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
 299         TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
 300 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 301         TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 302
 303 #ifdef CONFIG_HIGHMEM
 304 /*
 305  * Must use a macro here due to header dependency issues. page_zone() is not
 306  * available at this point.
 307  */
 308 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
 309 #else
 310 PAGEFLAG_FALSE(HighMem)
 311 #endif
 312
 313 #ifdef CONFIG_SWAP
 314 PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)
 315 #else
 316 PAGEFLAG_FALSE(SwapCache)
 317 #endif
 318
 319 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
 320         __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
 321         TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
 322
 323 #ifdef CONFIG_MMU
 324 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 325         __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 326         TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
 327 #else
 328 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
 329         TESTSCFLAG_FALSE(Mlocked)
 330 #endif
 331
 332 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 333 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
 334 #else
 335 PAGEFLAG_FALSE(Uncached)
 336 #endif
 337
 338 #ifdef CONFIG_MEMORY_FAILURE
 339 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 340 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 341 #define __PG_HWPOISON (1UL << PG_hwpoison)
 342 #else
 343 PAGEFLAG_FALSE(HWPoison)
 344 #define __PG_HWPOISON 0
 345 #endif
 346
 347 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 348 TESTPAGEFLAG(Young, young, PF_ANY)
 349 SETPAGEFLAG(Young, young, PF_ANY)
 350 TESTCLEARFLAG(Young, young, PF_ANY)
 351 PAGEFLAG(Idle, idle, PF_ANY)
 352 #endif
 353
 354 /*
 355  * On an anonymous page mapped into a user virtual memory area,
 356  * page->mapping points to its anon_vma, not to a struct address_space;
 357  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 358  *
 359  * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 360  * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
 361  * and then page->mapping points, not to an anon_vma, but to a private
 362  * structure which KSM associates with that merged page.  See ksm.h.
 363  *
 364  * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
 365  *
 366  * Please note that, confusingly, "page_mapping" refers to the inode
 367  * address_space which maps the page from disk; whereas "page_mapped"
 368  * refers to user virtual address space into which the page is mapped.
 369  */
 370 #define PAGE_MAPPING_ANON       1
 371 #define PAGE_MAPPING_KSM        2
 372 #define PAGE_MAPPING_FLAGS      (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
 373
 374 static __always_inline int PageAnonHead(struct page *page)
 375 {
 376         return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 377 }
 378
 379 static __always_inline int PageAnon(struct page *page)
 380 {
 381         page = compound_head(page);
 382         return PageAnonHead(page);
 383 }
 384
 385 #ifdef CONFIG_KSM
 386 /*
 387  * A KSM page is one of those write-protected "shared pages" or "merged pages"
 388  * which KSM maps into multiple mms, wherever identical anonymous page content
 389  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 390  * anon_vma, but to that page's node of the stable tree.
 391  */
 392 static __always_inline int PageKsm(struct page *page)
 393 {
 394         page = compound_head(page);
 395         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 396                                 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 397 }
 398 #else
 399 TESTPAGEFLAG_FALSE(Ksm)
 400 #endif
 401
 402 u64 stable_page_flags(struct page *page);
 403
 404 static inline int PageUptodate(struct page *page)
 405 {
 406         int ret;
 407         page = compound_head(page);
 408         ret = test_bit(PG_uptodate, &(page)->flags);
 409         /*
 410          * Must ensure that the data we read out of the page is loaded
 411          * _after_ we've loaded page->flags to check for PageUptodate.
 412          * We can skip the barrier if the page is not uptodate, because
 413          * we wouldn't be reading anything from it.
 414          *
 415          * See SetPageUptodate() for the other side of the story.
 416          */
 417         if (ret)
 418                 smp_rmb();
 419
 420         return ret;
 421 }
 422
 423 static __always_inline void __SetPageUptodate(struct page *page)
 424 {
 425         VM_BUG_ON_PAGE(PageTail(page), page);
 426         smp_wmb();
 427         __set_bit(PG_uptodate, &page->flags);
 428 }
 429
 430 static __always_inline void SetPageUptodate(struct page *page)
 431 {
 432         VM_BUG_ON_PAGE(PageTail(page), page);
 433         /*
 434          * Memory barrier must be issued before setting the PG_uptodate bit,
 435          * so that all previous stores issued in order to bring the page
 436          * uptodate are actually visible before PageUptodate becomes true.
 437          */
 438         smp_wmb();
 439         set_bit(PG_uptodate, &page->flags);
 440 }
 441
 442 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
 443
 444 int test_clear_page_writeback(struct page *page);
 445 int __test_set_page_writeback(struct page *page, bool keep_write);
 446
 447 #define test_set_page_writeback(page)                   \
 448         __test_set_page_writeback(page, false)
 449 #define test_set_page_writeback_keepwrite(page) \
 450         __test_set_page_writeback(page, true)
 451
 452 static inline void set_page_writeback(struct page *page)
 453 {
 454         test_set_page_writeback(page);
 455 }
 456
 457 static inline void set_page_writeback_keepwrite(struct page *page)
 458 {
 459         test_set_page_writeback_keepwrite(page);
 460 }
 461
 462 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
 463
 464 static __always_inline void set_compound_head(struct page *page, struct page *head)
 465 {
 466         WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
 467 }
 468
 469 static __always_inline void clear_compound_head(struct page *page)
 470 {
 471         WRITE_ONCE(page->compound_head, 0);
 472 }
 473
 474 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 475 static inline void ClearPageCompound(struct page *page)
 476 {
 477         BUG_ON(!PageHead(page));
 478         ClearPageHead(page);
 479 }
 480 #endif
 481
 482 #define PG_head_mask ((1UL << PG_head))
 483
 484 #ifdef CONFIG_HUGETLB_PAGE
 485 int PageHuge(struct page *page);
 486 int PageHeadHuge(struct page *page);
 487 bool page_huge_active(struct page *page);
 488 #else
 489 TESTPAGEFLAG_FALSE(Huge)
 490 TESTPAGEFLAG_FALSE(HeadHuge)
 491
 492 static inline bool page_huge_active(struct page *page)
 493 {
 494         return 0;
 495 }
 496 #endif
 497
 498
 499 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 500 /*
 501  * PageHuge() only returns true for hugetlbfs pages, but not for
 502  * normal or transparent huge pages.
 503  *
 504  * PageTransHuge() returns true for both transparent huge and
 505  * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 506  * called only in the core VM paths where hugetlbfs pages can't exist.
 507  */
 508 static inline int PageTransHuge(struct page *page)
 509 {
 510         VM_BUG_ON_PAGE(PageTail(page), page);
 511         return PageHead(page);
 512 }
 513
 514 /*
 515  * PageTransCompound returns true for both transparent huge pages
 516  * and hugetlbfs pages, so it should only be called when it's known
 517  * that hugetlbfs pages aren't involved.
 518  */
 519 static inline int PageTransCompound(struct page *page)
 520 {
 521         return PageCompound(page);
 522 }
 523
 524 /*
 525  * PageTransCompoundMap is the same as PageTransCompound, but it also
 526  * guarantees the primary MMU has the entire compound page mapped
 527  * through pmd_trans_huge, which in turn guarantees the secondary MMUs
 528  * can also map the entire compound page. This allows the secondary
 529  * MMUs to call get_user_pages() only once for each compound page and
 530  * to immediately map the entire compound page with a single secondary
 531  * MMU fault. If there will be a pmd split later, the secondary MMUs
 532  * will get an update through the MMU notifier invalidation through
 533  * split_huge_pmd().
 534  *
 535  * Unlike PageTransCompound, this is safe to be called only while
 536  * split_huge_pmd() cannot run from under us, like if protected by the
 537  * MMU notifier, otherwise it may result in page->_mapcount < 0 false
 538  * positives.
 539  */
 540 static inline int PageTransCompoundMap(struct page *page)
 541 {
 542         return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
 543 }
 544
 545 /*
 546  * PageTransTail returns true for both transparent huge pages
 547  * and hugetlbfs pages, so it should only be called when it's known
 548  * that hugetlbfs pages aren't involved.
 549  */
 550 static inline int PageTransTail(struct page *page)
 551 {
 552         return PageTail(page);
 553 }
 554
 555 /*
 556  * PageDoubleMap indicates that the compound page is mapped with PTEs as well
 557  * as PMDs.
 558  *
 559  * This is required for optimization of rmap operations for THP: we can postpone
 560  * per small page mapcount accounting (and its overhead from atomic operations)
 561  * until the first PMD split.
 562  *
 563  * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
 564  * by one. This reference will go away with last compound_mapcount.
 565  *
 566  * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
 567  */
 568 static inline int PageDoubleMap(struct page *page)
 569 {
 570         return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
 571 }
 572
 573 static inline int TestSetPageDoubleMap(struct page *page)
 574 {
 575         VM_BUG_ON_PAGE(!PageHead(page), page);
 576         return test_and_set_bit(PG_double_map, &page[1].flags);
 577 }
 578
 579 static inline int TestClearPageDoubleMap(struct page *page)
 580 {
 581         VM_BUG_ON_PAGE(!PageHead(page), page);
 582         return test_and_clear_bit(PG_double_map, &page[1].flags);
 583 }
 584
 585 #else
 586 TESTPAGEFLAG_FALSE(TransHuge)
 587 TESTPAGEFLAG_FALSE(TransCompound)
 588 TESTPAGEFLAG_FALSE(TransCompoundMap)
 589 TESTPAGEFLAG_FALSE(TransTail)
 590 TESTPAGEFLAG_FALSE(DoubleMap)
 591         TESTSETFLAG_FALSE(DoubleMap)
 592         TESTCLEARFLAG_FALSE(DoubleMap)
 593 #endif
 594
 595 /*
 596  * PageBuddy() indicate that the page is free and in the buddy system
 597  * (see mm/page_alloc.c).
 598  *
 599  * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
 600  * -2 so that an underflow of the page_mapcount() won't be mistaken
 601  * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
 602  * efficiently by most CPU architectures.
 603  */
 604 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
 605
 606 static inline int PageBuddy(struct page *page)
 607 {
 608         return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
 609 }
 610
 611 static inline void __SetPageBuddy(struct page *page)
 612 {
 613         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 614         atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 615 }
 616
 617 static inline void __ClearPageBuddy(struct page *page)
 618 {
 619         VM_BUG_ON_PAGE(!PageBuddy(page), page);
 620         atomic_set(&page->_mapcount, -1);
 621 }
 622
 623 extern bool is_free_buddy_page(struct page *page);
 624
 625 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
 626
 627 static inline int PageBalloon(struct page *page)
 628 {
 629         return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
 630 }
 631
 632 static inline void __SetPageBalloon(struct page *page)
 633 {
 634         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 635         atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
 636 }
 637
 638 static inline void __ClearPageBalloon(struct page *page)
 639 {
 640         VM_BUG_ON_PAGE(!PageBalloon(page), page);
 641         atomic_set(&page->_mapcount, -1);
 642 }
 643
 644 /*
 645  * If network-based swap is enabled, sl*b must keep track of whether pages
 646  * were allocated from pfmemalloc reserves.
 647  */
 648 static inline int PageSlabPfmemalloc(struct page *page)
 649 {
 650         VM_BUG_ON_PAGE(!PageSlab(page), page);
 651         return PageActive(page);
 652 }
 653
 654 static inline void SetPageSlabPfmemalloc(struct page *page)
 655 {
 656         VM_BUG_ON_PAGE(!PageSlab(page), page);
 657         SetPageActive(page);
 658 }
 659
 660 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 661 {
 662         VM_BUG_ON_PAGE(!PageSlab(page), page);
 663         __ClearPageActive(page);
 664 }
 665
 666 static inline void ClearPageSlabPfmemalloc(struct page *page)
 667 {
 668         VM_BUG_ON_PAGE(!PageSlab(page), page);
 669         ClearPageActive(page);
 670 }
 671
 672 #ifdef CONFIG_MMU
 673 #define __PG_MLOCKED            (1UL << PG_mlocked)
 674 #else
 675 #define __PG_MLOCKED            0
 676 #endif
 677
 678 /*
 679  * Flags checked when a page is freed.  Pages being freed should not have
 680  * these flags set.  It they are, there is a problem.
 681  */
 682 #define PAGE_FLAGS_CHECK_AT_FREE \
 683         (1UL << PG_lru   | 1UL << PG_locked    | \
 684          1UL << PG_private | 1UL << PG_private_2 | \
 685          1UL << PG_writeback | 1UL << PG_reserved | \
 686          1UL << PG_slab  | 1UL << PG_swapcache | 1UL << PG_active | \
 687          1UL << PG_unevictable | __PG_MLOCKED)
 688
 689 /*
 690  * Flags checked when a page is prepped for return by the page allocator.
 691  * Pages being prepped should not have these flags set.  It they are set,
 692  * there has been a kernel bug or struct page corruption.
 693  *
 694  * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 695  * alloc-free cycle to prevent from reusing the page.
 696  */
 697 #define PAGE_FLAGS_CHECK_AT_PREP        \
 698         (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
 699
 700 #define PAGE_FLAGS_PRIVATE                              \
 701         (1UL << PG_private | 1UL << PG_private_2)
 702 /**
 703  * page_has_private - Determine if page has private stuff
 704  * @page: The page to be checked
 705  *
 706  * Determine if a page has private stuff, indicating that release routines
 707  * should be invoked upon it.
 708  */
 709 static inline int page_has_private(struct page *page)
 710 {
 711         return !!(page->flags & PAGE_FLAGS_PRIVATE);
 712 }
 713
 714 #undef PF_ANY
 715 #undef PF_HEAD
 716 #undef PF_NO_TAIL
 717 #undef PF_NO_COMPOUND
 718 #endif /* !__GENERATING_BOUNDS_H */
 719
 720 #endif  /* PAGE_FLAGS_H */