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         /* non-lru isolated movable page */
 134         PG_isolated = PG_reclaim,
 135 };
 136
 137 #ifndef __GENERATING_BOUNDS_H
 138
 139 struct page;    /* forward declaration */
 140
 141 static inline struct page *compound_head(struct page *page)
 142 {
 143         unsigned long head = READ_ONCE(page->compound_head);
 144
 145         if (unlikely(head & 1))
 146                 return (struct page *) (head - 1);
 147         return page;
 148 }
 149
 150 static __always_inline int PageTail(struct page *page)
 151 {
 152         return READ_ONCE(page->compound_head) & 1;
 153 }
 154
 155 static __always_inline int PageCompound(struct page *page)
 156 {
 157         return test_bit(PG_head, &page->flags) || PageTail(page);
 158 }
 159
 160 /*
 161  * Page flags policies wrt compound pages
 162  *
 163  * PF_ANY:
 164  *     the page flag is relevant for small, head and tail pages.
 165  *
 166  * PF_HEAD:
 167  *     for compound page all operations related to the page flag applied to
 168  *     head page.
 169  *
 170  * PF_NO_TAIL:
 171  *     modifications of the page flag must be done on small or head pages,
 172  *     checks can be done on tail pages too.
 173  *
 174  * PF_NO_COMPOUND:
 175  *     the page flag is not relevant for compound pages.
 176  */
 177 #define PF_ANY(page, enforce)   page
 178 #define PF_HEAD(page, enforce)  compound_head(page)
 179 #define PF_NO_TAIL(page, enforce) ({                                    \
 180                 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);     \
 181                 compound_head(page);})
 182 #define PF_NO_COMPOUND(page, enforce) ({                                \
 183                 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
 184                 page;})
 185
 186 /*
 187  * Macros to create function definitions for page flags
 188  */
 189 #define TESTPAGEFLAG(uname, lname, policy)                              \
 190 static __always_inline int Page##uname(struct page *page)               \
 191         { return test_bit(PG_##lname, &policy(page, 0)->flags); }
 192
 193 #define SETPAGEFLAG(uname, lname, policy)                               \
 194 static __always_inline void SetPage##uname(struct page *page)           \
 195         { set_bit(PG_##lname, &policy(page, 1)->flags); }
 196
 197 #define CLEARPAGEFLAG(uname, lname, policy)                             \
 198 static __always_inline void ClearPage##uname(struct page *page)         \
 199         { clear_bit(PG_##lname, &policy(page, 1)->flags); }
 200
 201 #define __SETPAGEFLAG(uname, lname, policy)                             \
 202 static __always_inline void __SetPage##uname(struct page *page)         \
 203         { __set_bit(PG_##lname, &policy(page, 1)->flags); }
 204
 205 #define __CLEARPAGEFLAG(uname, lname, policy)                           \
 206 static __always_inline void __ClearPage##uname(struct page *page)       \
 207         { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
 208
 209 #define TESTSETFLAG(uname, lname, policy)                               \
 210 static __always_inline int TestSetPage##uname(struct page *page)        \
 211         { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
 212
 213 #define TESTCLEARFLAG(uname, lname, policy)                             \
 214 static __always_inline int TestClearPage##uname(struct page *page)      \
 215         { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
 216
 217 #define PAGEFLAG(uname, lname, policy)                                  \
 218         TESTPAGEFLAG(uname, lname, policy)                              \
 219         SETPAGEFLAG(uname, lname, policy)                               \
 220         CLEARPAGEFLAG(uname, lname, policy)
 221
 222 #define __PAGEFLAG(uname, lname, policy)                                \
 223         TESTPAGEFLAG(uname, lname, policy)                              \
 224         __SETPAGEFLAG(uname, lname, policy)                             \
 225         __CLEARPAGEFLAG(uname, lname, policy)
 226
 227 #define TESTSCFLAG(uname, lname, policy)                                \
 228         TESTSETFLAG(uname, lname, policy)                               \
 229         TESTCLEARFLAG(uname, lname, policy)
 230
 231 #define TESTPAGEFLAG_FALSE(uname)                                       \
 232 static inline int Page##uname(const struct page *page) { return 0; }
 233
 234 #define SETPAGEFLAG_NOOP(uname)                                         \
 235 static inline void SetPage##uname(struct page *page) {  }
 236
 237 #define CLEARPAGEFLAG_NOOP(uname)                                       \
 238 static inline void ClearPage##uname(struct page *page) {  }
 239
 240 #define __CLEARPAGEFLAG_NOOP(uname)                                     \
 241 static inline void __ClearPage##uname(struct page *page) {  }
 242
 243 #define TESTSETFLAG_FALSE(uname)                                        \
 244 static inline int TestSetPage##uname(struct page *page) { return 0; }
 245
 246 #define TESTCLEARFLAG_FALSE(uname)                                      \
 247 static inline int TestClearPage##uname(struct page *page) { return 0; }
 248
 249 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)                 \
 250         SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
 251
 252 #define TESTSCFLAG_FALSE(uname)                                         \
 253         TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 254
 255 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
 256 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 257 PAGEFLAG(Referenced, referenced, PF_HEAD)
 258         TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
 259         __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
 260 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
 261         __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
 262 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
 263 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
 264         TESTCLEARFLAG(Active, active, PF_HEAD)
 265 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
 266 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
 267 PAGEFLAG(Checked, checked, PF_NO_COMPOUND)         /* Used by some filesystems */
 268
 269 /* Xen */
 270 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
 271         TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
 272 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
 273 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
 274
 275 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 276         __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 277 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 278         __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 279         __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 280
 281 /*
 282  * Private page markings that may be used by the filesystem that owns the page
 283  * for its own purposes.
 284  * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 285  */
 286 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
 287         __CLEARPAGEFLAG(Private, private, PF_ANY)
 288 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
 289 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 290         TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 291
 292 /*
 293  * Only test-and-set exist for PG_writeback.  The unconditional operators are
 294  * risky: they bypass page accounting.
 295  */
 296 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
 297         TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
 298 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
 299
 300 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
 301 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
 302         TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
 303 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 304         TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 305
 306 #ifdef CONFIG_HIGHMEM
 307 /*
 308  * Must use a macro here due to header dependency issues. page_zone() is not
 309  * available at this point.
 310  */
 311 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
 312 #else
 313 PAGEFLAG_FALSE(HighMem)
 314 #endif
 315
 316 #ifdef CONFIG_SWAP
 317 PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)
 318 #else
 319 PAGEFLAG_FALSE(SwapCache)
 320 #endif
 321
 322 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
 323         __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
 324         TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
 325
 326 #ifdef CONFIG_MMU
 327 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 328         __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
 329         TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
 330 #else
 331 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
 332         TESTSCFLAG_FALSE(Mlocked)
 333 #endif
 334
 335 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 336 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
 337 #else
 338 PAGEFLAG_FALSE(Uncached)
 339 #endif
 340
 341 #ifdef CONFIG_MEMORY_FAILURE
 342 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 343 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 344 #define __PG_HWPOISON (1UL << PG_hwpoison)
 345 #else
 346 PAGEFLAG_FALSE(HWPoison)
 347 #define __PG_HWPOISON 0
 348 #endif
 349
 350 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
 351 TESTPAGEFLAG(Young, young, PF_ANY)
 352 SETPAGEFLAG(Young, young, PF_ANY)
 353 TESTCLEARFLAG(Young, young, PF_ANY)
 354 PAGEFLAG(Idle, idle, PF_ANY)
 355 #endif
 356
 357 /*
 358  * On an anonymous page mapped into a user virtual memory area,
 359  * page->mapping points to its anon_vma, not to a struct address_space;
 360  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 361  *
 362  * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 363  * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
 364  * bit; and then page->mapping points, not to an anon_vma, but to a private
 365  * structure which KSM associates with that merged page.  See ksm.h.
 366  *
 367  * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
 368  * page and then page->mapping points a struct address_space.
 369  *
 370  * Please note that, confusingly, "page_mapping" refers to the inode
 371  * address_space which maps the page from disk; whereas "page_mapped"
 372  * refers to user virtual address space into which the page is mapped.
 373  */
 374 #define PAGE_MAPPING_ANON       0x1
 375 #define PAGE_MAPPING_MOVABLE    0x2
 376 #define PAGE_MAPPING_KSM        (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 377 #define PAGE_MAPPING_FLAGS      (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 378
 379 static __always_inline int PageMappingFlags(struct page *page)
 380 {
 381         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
 382 }
 383
 384 static __always_inline int PageAnon(struct page *page)
 385 {
 386         page = compound_head(page);
 387         return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 388 }
 389
 390 static __always_inline int __PageMovable(struct page *page)
 391 {
 392         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 393                                 PAGE_MAPPING_MOVABLE;
 394 }
 395
 396 #ifdef CONFIG_KSM
 397 /*
 398  * A KSM page is one of those write-protected "shared pages" or "merged pages"
 399  * which KSM maps into multiple mms, wherever identical anonymous page content
 400  * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 401  * anon_vma, but to that page's node of the stable tree.
 402  */
 403 static __always_inline int PageKsm(struct page *page)
 404 {
 405         page = compound_head(page);
 406         return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 407                                 PAGE_MAPPING_KSM;
 408 }
 409 #else
 410 TESTPAGEFLAG_FALSE(Ksm)
 411 #endif
 412
 413 u64 stable_page_flags(struct page *page);
 414
 415 static inline int PageUptodate(struct page *page)
 416 {
 417         int ret;
 418         page = compound_head(page);
 419         ret = test_bit(PG_uptodate, &(page)->flags);
 420         /*
 421          * Must ensure that the data we read out of the page is loaded
 422          * _after_ we've loaded page->flags to check for PageUptodate.
 423          * We can skip the barrier if the page is not uptodate, because
 424          * we wouldn't be reading anything from it.
 425          *
 426          * See SetPageUptodate() for the other side of the story.
 427          */
 428         if (ret)
 429                 smp_rmb();
 430
 431         return ret;
 432 }
 433
 434 static __always_inline void __SetPageUptodate(struct page *page)
 435 {
 436         VM_BUG_ON_PAGE(PageTail(page), page);
 437         smp_wmb();
 438         __set_bit(PG_uptodate, &page->flags);
 439 }
 440
 441 static __always_inline void SetPageUptodate(struct page *page)
 442 {
 443         VM_BUG_ON_PAGE(PageTail(page), page);
 444         /*
 445          * Memory barrier must be issued before setting the PG_uptodate bit,
 446          * so that all previous stores issued in order to bring the page
 447          * uptodate are actually visible before PageUptodate becomes true.
 448          */
 449         smp_wmb();
 450         set_bit(PG_uptodate, &page->flags);
 451 }
 452
 453 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
 454
 455 int test_clear_page_writeback(struct page *page);
 456 int __test_set_page_writeback(struct page *page, bool keep_write);
 457
 458 #define test_set_page_writeback(page)                   \
 459         __test_set_page_writeback(page, false)
 460 #define test_set_page_writeback_keepwrite(page) \
 461         __test_set_page_writeback(page, true)
 462
 463 static inline void set_page_writeback(struct page *page)
 464 {
 465         test_set_page_writeback(page);
 466 }
 467
 468 static inline void set_page_writeback_keepwrite(struct page *page)
 469 {
 470         test_set_page_writeback_keepwrite(page);
 471 }
 472
 473 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
 474
 475 static __always_inline void set_compound_head(struct page *page, struct page *head)
 476 {
 477         WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
 478 }
 479
 480 static __always_inline void clear_compound_head(struct page *page)
 481 {
 482         WRITE_ONCE(page->compound_head, 0);
 483 }
 484
 485 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 486 static inline void ClearPageCompound(struct page *page)
 487 {
 488         BUG_ON(!PageHead(page));
 489         ClearPageHead(page);
 490 }
 491 #endif
 492
 493 #define PG_head_mask ((1UL << PG_head))
 494
 495 #ifdef CONFIG_HUGETLB_PAGE
 496 int PageHuge(struct page *page);
 497 int PageHeadHuge(struct page *page);
 498 bool page_huge_active(struct page *page);
 499 #else
 500 TESTPAGEFLAG_FALSE(Huge)
 501 TESTPAGEFLAG_FALSE(HeadHuge)
 502
 503 static inline bool page_huge_active(struct page *page)
 504 {
 505         return 0;
 506 }
 507 #endif
 508
 509
 510 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 511 /*
 512  * PageHuge() only returns true for hugetlbfs pages, but not for
 513  * normal or transparent huge pages.
 514  *
 515  * PageTransHuge() returns true for both transparent huge and
 516  * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 517  * called only in the core VM paths where hugetlbfs pages can't exist.
 518  */
 519 static inline int PageTransHuge(struct page *page)
 520 {
 521         VM_BUG_ON_PAGE(PageTail(page), page);
 522         return PageHead(page);
 523 }
 524
 525 /*
 526  * PageTransCompound returns true for both transparent huge pages
 527  * and hugetlbfs pages, so it should only be called when it's known
 528  * that hugetlbfs pages aren't involved.
 529  */
 530 static inline int PageTransCompound(struct page *page)
 531 {
 532         return PageCompound(page);
 533 }
 534
 535 /*
 536  * PageTransCompoundMap is the same as PageTransCompound, but it also
 537  * guarantees the primary MMU has the entire compound page mapped
 538  * through pmd_trans_huge, which in turn guarantees the secondary MMUs
 539  * can also map the entire compound page. This allows the secondary
 540  * MMUs to call get_user_pages() only once for each compound page and
 541  * to immediately map the entire compound page with a single secondary
 542  * MMU fault. If there will be a pmd split later, the secondary MMUs
 543  * will get an update through the MMU notifier invalidation through
 544  * split_huge_pmd().
 545  *
 546  * Unlike PageTransCompound, this is safe to be called only while
 547  * split_huge_pmd() cannot run from under us, like if protected by the
 548  * MMU notifier, otherwise it may result in page->_mapcount < 0 false
 549  * positives.
 550  */
 551 static inline int PageTransCompoundMap(struct page *page)
 552 {
 553         return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
 554 }
 555
 556 /*
 557  * PageTransTail returns true for both transparent huge pages
 558  * and hugetlbfs pages, so it should only be called when it's known
 559  * that hugetlbfs pages aren't involved.
 560  */
 561 static inline int PageTransTail(struct page *page)
 562 {
 563         return PageTail(page);
 564 }
 565
 566 /*
 567  * PageDoubleMap indicates that the compound page is mapped with PTEs as well
 568  * as PMDs.
 569  *
 570  * This is required for optimization of rmap operations for THP: we can postpone
 571  * per small page mapcount accounting (and its overhead from atomic operations)
 572  * until the first PMD split.
 573  *
 574  * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
 575  * by one. This reference will go away with last compound_mapcount.
 576  *
 577  * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
 578  */
 579 static inline int PageDoubleMap(struct page *page)
 580 {
 581         return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
 582 }
 583
 584 static inline void SetPageDoubleMap(struct page *page)
 585 {
 586         VM_BUG_ON_PAGE(!PageHead(page), page);
 587         set_bit(PG_double_map, &page[1].flags);
 588 }
 589
 590 static inline void ClearPageDoubleMap(struct page *page)
 591 {
 592         VM_BUG_ON_PAGE(!PageHead(page), page);
 593         clear_bit(PG_double_map, &page[1].flags);
 594 }
 595 static inline int TestSetPageDoubleMap(struct page *page)
 596 {
 597         VM_BUG_ON_PAGE(!PageHead(page), page);
 598         return test_and_set_bit(PG_double_map, &page[1].flags);
 599 }
 600
 601 static inline int TestClearPageDoubleMap(struct page *page)
 602 {
 603         VM_BUG_ON_PAGE(!PageHead(page), page);
 604         return test_and_clear_bit(PG_double_map, &page[1].flags);
 605 }
 606
 607 #else
 608 TESTPAGEFLAG_FALSE(TransHuge)
 609 TESTPAGEFLAG_FALSE(TransCompound)
 610 TESTPAGEFLAG_FALSE(TransCompoundMap)
 611 TESTPAGEFLAG_FALSE(TransTail)
 612 PAGEFLAG_FALSE(DoubleMap)
 613         TESTSETFLAG_FALSE(DoubleMap)
 614         TESTCLEARFLAG_FALSE(DoubleMap)
 615 #endif
 616
 617 /*
 618  * For pages that are never mapped to userspace, page->mapcount may be
 619  * used for storing extra information about page type. Any value used
 620  * for this purpose must be <= -2, but it's better start not too close
 621  * to -2 so that an underflow of the page_mapcount() won't be mistaken
 622  * for a special page.
 623  */
 624 #define PAGE_MAPCOUNT_OPS(uname, lname)                                 \
 625 static __always_inline int Page##uname(struct page *page)               \
 626 {                                                                       \
 627         return atomic_read(&page->_mapcount) ==                         \
 628                                 PAGE_##lname##_MAPCOUNT_VALUE;          \
 629 }                                                                       \
 630 static __always_inline void __SetPage##uname(struct page *page)         \
 631 {                                                                       \
 632         VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);      \
 633         atomic_set(&page->_mapcount, PAGE_##lname##_MAPCOUNT_VALUE);    \
 634 }                                                                       \
 635 static __always_inline void __ClearPage##uname(struct page *page)       \
 636 {                                                                       \
 637         VM_BUG_ON_PAGE(!Page##uname(page), page);                       \
 638         atomic_set(&page->_mapcount, -1);                               \
 639 }
 640
 641 /*
 642  * PageBuddy() indicate that the page is free and in the buddy system
 643  * (see mm/page_alloc.c).
 644  */
 645 #define PAGE_BUDDY_MAPCOUNT_VALUE               (-128)
 646 PAGE_MAPCOUNT_OPS(Buddy, BUDDY)
 647
 648 /*
 649  * PageBalloon() is set on pages that are on the balloon page list
 650  * (see mm/balloon_compaction.c).
 651  */
 652 #define PAGE_BALLOON_MAPCOUNT_VALUE             (-256)
 653 PAGE_MAPCOUNT_OPS(Balloon, BALLOON)
 654
 655 /*
 656  * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
 657  * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
 658  */
 659 #define PAGE_KMEMCG_MAPCOUNT_VALUE              (-512)
 660 PAGE_MAPCOUNT_OPS(Kmemcg, KMEMCG)
 661
 662 extern bool is_free_buddy_page(struct page *page);
 663
 664 __PAGEFLAG(Isolated, isolated, PF_ANY);
 665
 666 /*
 667  * If network-based swap is enabled, sl*b must keep track of whether pages
 668  * were allocated from pfmemalloc reserves.
 669  */
 670 static inline int PageSlabPfmemalloc(struct page *page)
 671 {
 672         VM_BUG_ON_PAGE(!PageSlab(page), page);
 673         return PageActive(page);
 674 }
 675
 676 static inline void SetPageSlabPfmemalloc(struct page *page)
 677 {
 678         VM_BUG_ON_PAGE(!PageSlab(page), page);
 679         SetPageActive(page);
 680 }
 681
 682 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 683 {
 684         VM_BUG_ON_PAGE(!PageSlab(page), page);
 685         __ClearPageActive(page);
 686 }
 687
 688 static inline void ClearPageSlabPfmemalloc(struct page *page)
 689 {
 690         VM_BUG_ON_PAGE(!PageSlab(page), page);
 691         ClearPageActive(page);
 692 }
 693
 694 #ifdef CONFIG_MMU
 695 #define __PG_MLOCKED            (1UL << PG_mlocked)
 696 #else
 697 #define __PG_MLOCKED            0
 698 #endif
 699
 700 /*
 701  * Flags checked when a page is freed.  Pages being freed should not have
 702  * these flags set.  It they are, there is a problem.
 703  */
 704 #define PAGE_FLAGS_CHECK_AT_FREE \
 705         (1UL << PG_lru   | 1UL << PG_locked    | \
 706          1UL << PG_private | 1UL << PG_private_2 | \
 707          1UL << PG_writeback | 1UL << PG_reserved | \
 708          1UL << PG_slab  | 1UL << PG_swapcache | 1UL << PG_active | \
 709          1UL << PG_unevictable | __PG_MLOCKED)
 710
 711 /*
 712  * Flags checked when a page is prepped for return by the page allocator.
 713  * Pages being prepped should not have these flags set.  It they are set,
 714  * there has been a kernel bug or struct page corruption.
 715  *
 716  * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 717  * alloc-free cycle to prevent from reusing the page.
 718  */
 719 #define PAGE_FLAGS_CHECK_AT_PREP        \
 720         (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
 721
 722 #define PAGE_FLAGS_PRIVATE                              \
 723         (1UL << PG_private | 1UL << PG_private_2)
 724 /**
 725  * page_has_private - Determine if page has private stuff
 726  * @page: The page to be checked
 727  *
 728  * Determine if a page has private stuff, indicating that release routines
 729  * should be invoked upon it.
 730  */
 731 static inline int page_has_private(struct page *page)
 732 {
 733         return !!(page->flags & PAGE_FLAGS_PRIVATE);
 734 }
 735
 736 #undef PF_ANY
 737 #undef PF_HEAD
 738 #undef PF_NO_TAIL
 739 #undef PF_NO_COMPOUND
 740 #endif /* !__GENERATING_BOUNDS_H */
 741
 742 #endif  /* PAGE_FLAGS_H */