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1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Macros for manipulating and testing page->flags
9 #include <linux/types.h>
10 #include <linux/bug.h>
11 #include <linux/mmdebug.h>
12 #ifndef __GENERATING_BOUNDS_H
13 #include <linux/mm_types.h>
14 #include <generated/bounds.h>
15 #endif /* !__GENERATING_BOUNDS_H */
18 * Various page->flags bits:
20 * PG_reserved is set for special pages. The "struct page" of such a page
21 * should in general not be touched (e.g. set dirty) except by its owner.
22 * Pages marked as PG_reserved include:
23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
25 * - Pages reserved or allocated early during boot (before the page allocator
26 * was initialized). This includes (depending on the architecture) the
27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
28 * much more. Once (if ever) freed, PG_reserved is cleared and they will
29 * be given to the page allocator.
30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
31 * to read/write these pages might end badly. Don't touch!
33 * - Pages not added to the page allocator when onlining a section because
34 * they were excluded via the online_page_callback() or because they are
36 * - Pages allocated in the context of kexec/kdump (loaded kernel image,
37 * control pages, vmcoreinfo)
38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
39 * not marked PG_reserved (as they might be in use by somebody else who does
40 * not respect the caching strategy).
41 * - Pages part of an offline section (struct pages of offline sections should
42 * not be trusted as they will be initialized when first onlined).
44 * - Pages holding CPU notes for POWER Firmware Assisted Dump
45 * - Device memory (e.g. PMEM, DAX, HMM)
46 * Some PG_reserved pages will be excluded from the hibernation image.
47 * PG_reserved does in general not hinder anybody from dumping or swapping
48 * and is no longer required for remap_pfn_range(). ioremap might require it.
49 * Consequently, PG_reserved for a page mapped into user space can indicate
50 * the zero page, the vDSO, MMIO pages or device memory.
52 * The PG_private bitflag is set on pagecache pages if they contain filesystem
53 * specific data (which is normally at page->private). It can be used by
54 * private allocations for its own usage.
56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
58 * is set before writeback starts and cleared when it finishes.
60 * PG_locked also pins a page in pagecache, and blocks truncation of the file
63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
66 * PG_swapbacked is set when a page uses swap as a backing storage. This are
67 * usually PageAnon or shmem pages but please note that even anonymous pages
68 * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
69 * a result of MADV_FREE).
71 * PG_uptodate tells whether the page's contents is valid. When a read
72 * completes, the page becomes uptodate, unless a disk I/O error happened.
74 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
75 * file-backed pagecache (see mm/vmscan.c).
77 * PG_error is set to indicate that an I/O error occurred on this page.
79 * PG_arch_1 is an architecture specific page state bit. The generic code
80 * guarantees that this bit is cleared for a page when it first is entered into
83 * PG_hwpoison indicates that a page got corrupted in hardware and contains
84 * data with incorrect ECC bits that triggered a machine check. Accessing is
85 * not safe since it may cause another machine check. Don't touch!
89 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
90 * locked- and dirty-page accounting.
92 * The page flags field is split into two parts, the main flags area
93 * which extends from the low bits upwards, and the fields area which
94 * extends from the high bits downwards.
96 * | FIELD | ... | FLAGS |
100 * The fields area is reserved for fields mapping zone, node (for NUMA) and
101 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
102 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
105 PG_locked
, /* Page is locked. Don't touch. */
112 PG_waiters
, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
115 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
118 PG_private
, /* If pagecache, has fs-private data */
119 PG_private_2
, /* If pagecache, has fs aux data */
120 PG_writeback
, /* Page is under writeback */
121 PG_head
, /* A head page */
122 PG_mappedtodisk
, /* Has blocks allocated on-disk */
123 PG_reclaim
, /* To be reclaimed asap */
124 PG_swapbacked
, /* Page is backed by RAM/swap */
125 PG_unevictable
, /* Page is "unevictable" */
127 PG_mlocked
, /* Page is vma mlocked */
129 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
130 PG_uncached
, /* Page has been mapped as uncached */
132 #ifdef CONFIG_MEMORY_FAILURE
133 PG_hwpoison
, /* hardware poisoned page. Don't touch */
135 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
142 PG_checked
= PG_owner_priv_1
,
145 PG_swapcache
= PG_owner_priv_1
, /* Swap page: swp_entry_t in private */
147 /* Two page bits are conscripted by FS-Cache to maintain local caching
148 * state. These bits are set on pages belonging to the netfs's inodes
149 * when those inodes are being locally cached.
151 PG_fscache
= PG_private_2
, /* page backed by cache */
154 /* Pinned in Xen as a read-only pagetable page. */
155 PG_pinned
= PG_owner_priv_1
,
156 /* Pinned as part of domain save (see xen_mm_pin_all()). */
157 PG_savepinned
= PG_dirty
,
158 /* Has a grant mapping of another (foreign) domain's page. */
159 PG_foreign
= PG_owner_priv_1
,
160 /* Remapped by swiotlb-xen. */
161 PG_xen_remapped
= PG_owner_priv_1
,
164 PG_slob_free
= PG_private
,
166 /* Compound pages. Stored in first tail page's flags */
167 PG_double_map
= PG_private_2
,
169 /* non-lru isolated movable page */
170 PG_isolated
= PG_reclaim
,
172 /* Only valid for buddy pages. Used to track pages that are reported */
173 PG_reported
= PG_uptodate
,
176 #ifndef __GENERATING_BOUNDS_H
178 struct page
; /* forward declaration */
180 static inline struct page
*compound_head(struct page
*page
)
182 unsigned long head
= READ_ONCE(page
->compound_head
);
184 if (unlikely(head
& 1))
185 return (struct page
*) (head
- 1);
189 static __always_inline
int PageTail(struct page
*page
)
191 return READ_ONCE(page
->compound_head
) & 1;
194 static __always_inline
int PageCompound(struct page
*page
)
196 return test_bit(PG_head
, &page
->flags
) || PageTail(page
);
199 #define PAGE_POISON_PATTERN -1l
200 static inline int PagePoisoned(const struct page
*page
)
202 return page
->flags
== PAGE_POISON_PATTERN
;
205 #ifdef CONFIG_DEBUG_VM
206 void page_init_poison(struct page
*page
, size_t size
);
208 static inline void page_init_poison(struct page
*page
, size_t size
)
214 * Page flags policies wrt compound pages
217 * check if this struct page poisoned/uninitialized
220 * the page flag is relevant for small, head and tail pages.
223 * for compound page all operations related to the page flag applied to
227 * for compound page, callers only ever operate on the head page.
230 * modifications of the page flag must be done on small or head pages,
231 * checks can be done on tail pages too.
234 * the page flag is not relevant for compound pages.
236 #define PF_POISONED_CHECK(page) ({ \
237 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
239 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
240 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
241 #define PF_ONLY_HEAD(page, enforce) ({ \
242 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
243 PF_POISONED_CHECK(page); })
244 #define PF_NO_TAIL(page, enforce) ({ \
245 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
246 PF_POISONED_CHECK(compound_head(page)); })
247 #define PF_NO_COMPOUND(page, enforce) ({ \
248 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
249 PF_POISONED_CHECK(page); })
252 * Macros to create function definitions for page flags
254 #define TESTPAGEFLAG(uname, lname, policy) \
255 static __always_inline int Page##uname(struct page *page) \
256 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
258 #define SETPAGEFLAG(uname, lname, policy) \
259 static __always_inline void SetPage##uname(struct page *page) \
260 { set_bit(PG_##lname, &policy(page, 1)->flags); }
262 #define CLEARPAGEFLAG(uname, lname, policy) \
263 static __always_inline void ClearPage##uname(struct page *page) \
264 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
266 #define __SETPAGEFLAG(uname, lname, policy) \
267 static __always_inline void __SetPage##uname(struct page *page) \
268 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
270 #define __CLEARPAGEFLAG(uname, lname, policy) \
271 static __always_inline void __ClearPage##uname(struct page *page) \
272 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
274 #define TESTSETFLAG(uname, lname, policy) \
275 static __always_inline int TestSetPage##uname(struct page *page) \
276 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
278 #define TESTCLEARFLAG(uname, lname, policy) \
279 static __always_inline int TestClearPage##uname(struct page *page) \
280 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
282 #define PAGEFLAG(uname, lname, policy) \
283 TESTPAGEFLAG(uname, lname, policy) \
284 SETPAGEFLAG(uname, lname, policy) \
285 CLEARPAGEFLAG(uname, lname, policy)
287 #define __PAGEFLAG(uname, lname, policy) \
288 TESTPAGEFLAG(uname, lname, policy) \
289 __SETPAGEFLAG(uname, lname, policy) \
290 __CLEARPAGEFLAG(uname, lname, policy)
292 #define TESTSCFLAG(uname, lname, policy) \
293 TESTSETFLAG(uname, lname, policy) \
294 TESTCLEARFLAG(uname, lname, policy)
296 #define TESTPAGEFLAG_FALSE(uname) \
297 static inline int Page##uname(const struct page *page) { return 0; }
299 #define SETPAGEFLAG_NOOP(uname) \
300 static inline void SetPage##uname(struct page *page) { }
302 #define CLEARPAGEFLAG_NOOP(uname) \
303 static inline void ClearPage##uname(struct page *page) { }
305 #define __CLEARPAGEFLAG_NOOP(uname) \
306 static inline void __ClearPage##uname(struct page *page) { }
308 #define TESTSETFLAG_FALSE(uname) \
309 static inline int TestSetPage##uname(struct page *page) { return 0; }
311 #define TESTCLEARFLAG_FALSE(uname) \
312 static inline int TestClearPage##uname(struct page *page) { return 0; }
314 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
315 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
317 #define TESTSCFLAG_FALSE(uname) \
318 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
320 __PAGEFLAG(Locked
, locked
, PF_NO_TAIL
)
321 PAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
) __CLEARPAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
)
322 PAGEFLAG(Error
, error
, PF_NO_TAIL
) TESTCLEARFLAG(Error
, error
, PF_NO_TAIL
)
323 PAGEFLAG(Referenced
, referenced
, PF_HEAD
)
324 TESTCLEARFLAG(Referenced
, referenced
, PF_HEAD
)
325 __SETPAGEFLAG(Referenced
, referenced
, PF_HEAD
)
326 PAGEFLAG(Dirty
, dirty
, PF_HEAD
) TESTSCFLAG(Dirty
, dirty
, PF_HEAD
)
327 __CLEARPAGEFLAG(Dirty
, dirty
, PF_HEAD
)
328 PAGEFLAG(LRU
, lru
, PF_HEAD
) __CLEARPAGEFLAG(LRU
, lru
, PF_HEAD
)
329 PAGEFLAG(Active
, active
, PF_HEAD
) __CLEARPAGEFLAG(Active
, active
, PF_HEAD
)
330 TESTCLEARFLAG(Active
, active
, PF_HEAD
)
331 PAGEFLAG(Workingset
, workingset
, PF_HEAD
)
332 TESTCLEARFLAG(Workingset
, workingset
, PF_HEAD
)
333 __PAGEFLAG(Slab
, slab
, PF_NO_TAIL
)
334 __PAGEFLAG(SlobFree
, slob_free
, PF_NO_TAIL
)
335 PAGEFLAG(Checked
, checked
, PF_NO_COMPOUND
) /* Used by some filesystems */
338 PAGEFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
339 TESTSCFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
340 PAGEFLAG(SavePinned
, savepinned
, PF_NO_COMPOUND
);
341 PAGEFLAG(Foreign
, foreign
, PF_NO_COMPOUND
);
342 PAGEFLAG(XenRemapped
, xen_remapped
, PF_NO_COMPOUND
)
343 TESTCLEARFLAG(XenRemapped
, xen_remapped
, PF_NO_COMPOUND
)
345 PAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
346 __CLEARPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
347 __SETPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
348 PAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
349 __CLEARPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
350 __SETPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
353 * Private page markings that may be used by the filesystem that owns the page
354 * for its own purposes.
355 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
357 PAGEFLAG(Private
, private, PF_ANY
) __SETPAGEFLAG(Private
, private, PF_ANY
)
358 __CLEARPAGEFLAG(Private
, private, PF_ANY
)
359 PAGEFLAG(Private2
, private_2
, PF_ANY
) TESTSCFLAG(Private2
, private_2
, PF_ANY
)
360 PAGEFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
361 TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
364 * Only test-and-set exist for PG_writeback. The unconditional operators are
365 * risky: they bypass page accounting.
367 TESTPAGEFLAG(Writeback
, writeback
, PF_NO_TAIL
)
368 TESTSCFLAG(Writeback
, writeback
, PF_NO_TAIL
)
369 PAGEFLAG(MappedToDisk
, mappedtodisk
, PF_NO_TAIL
)
371 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
372 PAGEFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
373 TESTCLEARFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
374 PAGEFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
375 TESTCLEARFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
377 #ifdef CONFIG_HIGHMEM
379 * Must use a macro here due to header dependency issues. page_zone() is not
380 * available at this point.
382 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
384 PAGEFLAG_FALSE(HighMem
)
388 static __always_inline
int PageSwapCache(struct page
*page
)
390 #ifdef CONFIG_THP_SWAP
391 page
= compound_head(page
);
393 return PageSwapBacked(page
) && test_bit(PG_swapcache
, &page
->flags
);
396 SETPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
397 CLEARPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
399 PAGEFLAG_FALSE(SwapCache
)
402 PAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
403 __CLEARPAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
404 TESTCLEARFLAG(Unevictable
, unevictable
, PF_HEAD
)
407 PAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
408 __CLEARPAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
409 TESTSCFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
411 PAGEFLAG_FALSE(Mlocked
) __CLEARPAGEFLAG_NOOP(Mlocked
)
412 TESTSCFLAG_FALSE(Mlocked
)
415 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
416 PAGEFLAG(Uncached
, uncached
, PF_NO_COMPOUND
)
418 PAGEFLAG_FALSE(Uncached
)
421 #ifdef CONFIG_MEMORY_FAILURE
422 PAGEFLAG(HWPoison
, hwpoison
, PF_ANY
)
423 TESTSCFLAG(HWPoison
, hwpoison
, PF_ANY
)
424 #define __PG_HWPOISON (1UL << PG_hwpoison)
425 extern bool set_hwpoison_free_buddy_page(struct page
*page
);
427 PAGEFLAG_FALSE(HWPoison
)
428 static inline bool set_hwpoison_free_buddy_page(struct page
*page
)
432 #define __PG_HWPOISON 0
435 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
436 TESTPAGEFLAG(Young
, young
, PF_ANY
)
437 SETPAGEFLAG(Young
, young
, PF_ANY
)
438 TESTCLEARFLAG(Young
, young
, PF_ANY
)
439 PAGEFLAG(Idle
, idle
, PF_ANY
)
443 * PageReported() is used to track reported free pages within the Buddy
444 * allocator. We can use the non-atomic version of the test and set
445 * operations as both should be shielded with the zone lock to prevent
446 * any possible races on the setting or clearing of the bit.
448 __PAGEFLAG(Reported
, reported
, PF_NO_COMPOUND
)
451 * On an anonymous page mapped into a user virtual memory area,
452 * page->mapping points to its anon_vma, not to a struct address_space;
453 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
455 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
456 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
457 * bit; and then page->mapping points, not to an anon_vma, but to a private
458 * structure which KSM associates with that merged page. See ksm.h.
460 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
461 * page and then page->mapping points a struct address_space.
463 * Please note that, confusingly, "page_mapping" refers to the inode
464 * address_space which maps the page from disk; whereas "page_mapped"
465 * refers to user virtual address space into which the page is mapped.
467 #define PAGE_MAPPING_ANON 0x1
468 #define PAGE_MAPPING_MOVABLE 0x2
469 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
470 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
472 static __always_inline
int PageMappingFlags(struct page
*page
)
474 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) != 0;
477 static __always_inline
int PageAnon(struct page
*page
)
479 page
= compound_head(page
);
480 return ((unsigned long)page
->mapping
& PAGE_MAPPING_ANON
) != 0;
483 static __always_inline
int __PageMovable(struct page
*page
)
485 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
486 PAGE_MAPPING_MOVABLE
;
491 * A KSM page is one of those write-protected "shared pages" or "merged pages"
492 * which KSM maps into multiple mms, wherever identical anonymous page content
493 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
494 * anon_vma, but to that page's node of the stable tree.
496 static __always_inline
int PageKsm(struct page
*page
)
498 page
= compound_head(page
);
499 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
503 TESTPAGEFLAG_FALSE(Ksm
)
506 u64
stable_page_flags(struct page
*page
);
508 static inline int PageUptodate(struct page
*page
)
511 page
= compound_head(page
);
512 ret
= test_bit(PG_uptodate
, &(page
)->flags
);
514 * Must ensure that the data we read out of the page is loaded
515 * _after_ we've loaded page->flags to check for PageUptodate.
516 * We can skip the barrier if the page is not uptodate, because
517 * we wouldn't be reading anything from it.
519 * See SetPageUptodate() for the other side of the story.
527 static __always_inline
void __SetPageUptodate(struct page
*page
)
529 VM_BUG_ON_PAGE(PageTail(page
), page
);
531 __set_bit(PG_uptodate
, &page
->flags
);
534 static __always_inline
void SetPageUptodate(struct page
*page
)
536 VM_BUG_ON_PAGE(PageTail(page
), page
);
538 * Memory barrier must be issued before setting the PG_uptodate bit,
539 * so that all previous stores issued in order to bring the page
540 * uptodate are actually visible before PageUptodate becomes true.
543 set_bit(PG_uptodate
, &page
->flags
);
546 CLEARPAGEFLAG(Uptodate
, uptodate
, PF_NO_TAIL
)
548 int test_clear_page_writeback(struct page
*page
);
549 int __test_set_page_writeback(struct page
*page
, bool keep_write
);
551 #define test_set_page_writeback(page) \
552 __test_set_page_writeback(page, false)
553 #define test_set_page_writeback_keepwrite(page) \
554 __test_set_page_writeback(page, true)
556 static inline void set_page_writeback(struct page
*page
)
558 test_set_page_writeback(page
);
561 static inline void set_page_writeback_keepwrite(struct page
*page
)
563 test_set_page_writeback_keepwrite(page
);
566 __PAGEFLAG(Head
, head
, PF_ANY
) CLEARPAGEFLAG(Head
, head
, PF_ANY
)
568 static __always_inline
void set_compound_head(struct page
*page
, struct page
*head
)
570 WRITE_ONCE(page
->compound_head
, (unsigned long)head
+ 1);
573 static __always_inline
void clear_compound_head(struct page
*page
)
575 WRITE_ONCE(page
->compound_head
, 0);
578 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
579 static inline void ClearPageCompound(struct page
*page
)
581 BUG_ON(!PageHead(page
));
586 #define PG_head_mask ((1UL << PG_head))
588 #ifdef CONFIG_HUGETLB_PAGE
589 int PageHuge(struct page
*page
);
590 int PageHeadHuge(struct page
*page
);
591 bool page_huge_active(struct page
*page
);
593 TESTPAGEFLAG_FALSE(Huge
)
594 TESTPAGEFLAG_FALSE(HeadHuge
)
596 static inline bool page_huge_active(struct page
*page
)
603 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
605 * PageHuge() only returns true for hugetlbfs pages, but not for
606 * normal or transparent huge pages.
608 * PageTransHuge() returns true for both transparent huge and
609 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
610 * called only in the core VM paths where hugetlbfs pages can't exist.
612 static inline int PageTransHuge(struct page
*page
)
614 VM_BUG_ON_PAGE(PageTail(page
), page
);
615 return PageHead(page
);
619 * PageTransCompound returns true for both transparent huge pages
620 * and hugetlbfs pages, so it should only be called when it's known
621 * that hugetlbfs pages aren't involved.
623 static inline int PageTransCompound(struct page
*page
)
625 return PageCompound(page
);
629 * PageTransCompoundMap is the same as PageTransCompound, but it also
630 * guarantees the primary MMU has the entire compound page mapped
631 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
632 * can also map the entire compound page. This allows the secondary
633 * MMUs to call get_user_pages() only once for each compound page and
634 * to immediately map the entire compound page with a single secondary
635 * MMU fault. If there will be a pmd split later, the secondary MMUs
636 * will get an update through the MMU notifier invalidation through
639 * Unlike PageTransCompound, this is safe to be called only while
640 * split_huge_pmd() cannot run from under us, like if protected by the
641 * MMU notifier, otherwise it may result in page->_mapcount check false
644 * We have to treat page cache THP differently since every subpage of it
645 * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE
646 * mapped in the current process so comparing subpage's _mapcount to
647 * compound_mapcount to filter out PTE mapped case.
649 static inline int PageTransCompoundMap(struct page
*page
)
653 if (!PageTransCompound(page
))
657 return atomic_read(&page
->_mapcount
) < 0;
659 head
= compound_head(page
);
660 /* File THP is PMD mapped and not PTE mapped */
661 return atomic_read(&page
->_mapcount
) ==
662 atomic_read(compound_mapcount_ptr(head
));
666 * PageTransTail returns true for both transparent huge pages
667 * and hugetlbfs pages, so it should only be called when it's known
668 * that hugetlbfs pages aren't involved.
670 static inline int PageTransTail(struct page
*page
)
672 return PageTail(page
);
676 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
679 * This is required for optimization of rmap operations for THP: we can postpone
680 * per small page mapcount accounting (and its overhead from atomic operations)
681 * until the first PMD split.
683 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
684 * by one. This reference will go away with last compound_mapcount.
686 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
688 static inline int PageDoubleMap(struct page
*page
)
690 return PageHead(page
) && test_bit(PG_double_map
, &page
[1].flags
);
693 static inline void SetPageDoubleMap(struct page
*page
)
695 VM_BUG_ON_PAGE(!PageHead(page
), page
);
696 set_bit(PG_double_map
, &page
[1].flags
);
699 static inline void ClearPageDoubleMap(struct page
*page
)
701 VM_BUG_ON_PAGE(!PageHead(page
), page
);
702 clear_bit(PG_double_map
, &page
[1].flags
);
704 static inline int TestSetPageDoubleMap(struct page
*page
)
706 VM_BUG_ON_PAGE(!PageHead(page
), page
);
707 return test_and_set_bit(PG_double_map
, &page
[1].flags
);
710 static inline int TestClearPageDoubleMap(struct page
*page
)
712 VM_BUG_ON_PAGE(!PageHead(page
), page
);
713 return test_and_clear_bit(PG_double_map
, &page
[1].flags
);
717 TESTPAGEFLAG_FALSE(TransHuge
)
718 TESTPAGEFLAG_FALSE(TransCompound
)
719 TESTPAGEFLAG_FALSE(TransCompoundMap
)
720 TESTPAGEFLAG_FALSE(TransTail
)
721 PAGEFLAG_FALSE(DoubleMap
)
722 TESTSETFLAG_FALSE(DoubleMap
)
723 TESTCLEARFLAG_FALSE(DoubleMap
)
727 * For pages that are never mapped to userspace (and aren't PageSlab),
728 * page_type may be used. Because it is initialised to -1, we invert the
729 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
730 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
731 * low bits so that an underflow or overflow of page_mapcount() won't be
732 * mistaken for a page type value.
735 #define PAGE_TYPE_BASE 0xf0000000
736 /* Reserve 0x0000007f to catch underflows of page_mapcount */
737 #define PAGE_MAPCOUNT_RESERVE -128
738 #define PG_buddy 0x00000080
739 #define PG_offline 0x00000100
740 #define PG_kmemcg 0x00000200
741 #define PG_table 0x00000400
742 #define PG_guard 0x00000800
744 #define PageType(page, flag) \
745 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
747 static inline int page_has_type(struct page
*page
)
749 return (int)page
->page_type
< PAGE_MAPCOUNT_RESERVE
;
752 #define PAGE_TYPE_OPS(uname, lname) \
753 static __always_inline int Page##uname(struct page *page) \
755 return PageType(page, PG_##lname); \
757 static __always_inline void __SetPage##uname(struct page *page) \
759 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
760 page->page_type &= ~PG_##lname; \
762 static __always_inline void __ClearPage##uname(struct page *page) \
764 VM_BUG_ON_PAGE(!Page##uname(page), page); \
765 page->page_type |= PG_##lname; \
769 * PageBuddy() indicates that the page is free and in the buddy system
770 * (see mm/page_alloc.c).
772 PAGE_TYPE_OPS(Buddy
, buddy
)
775 * PageOffline() indicates that the page is logically offline although the
776 * containing section is online. (e.g. inflated in a balloon driver or
777 * not onlined when onlining the section).
778 * The content of these pages is effectively stale. Such pages should not
779 * be touched (read/write/dump/save) except by their owner.
781 PAGE_TYPE_OPS(Offline
, offline
)
784 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
785 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
787 PAGE_TYPE_OPS(Kmemcg
, kmemcg
)
790 * Marks pages in use as page tables.
792 PAGE_TYPE_OPS(Table
, table
)
795 * Marks guardpages used with debug_pagealloc.
797 PAGE_TYPE_OPS(Guard
, guard
)
799 extern bool is_free_buddy_page(struct page
*page
);
801 __PAGEFLAG(Isolated
, isolated
, PF_ANY
);
804 * If network-based swap is enabled, sl*b must keep track of whether pages
805 * were allocated from pfmemalloc reserves.
807 static inline int PageSlabPfmemalloc(struct page
*page
)
809 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
810 return PageActive(page
);
813 static inline void SetPageSlabPfmemalloc(struct page
*page
)
815 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
819 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
821 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
822 __ClearPageActive(page
);
825 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
827 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
828 ClearPageActive(page
);
832 #define __PG_MLOCKED (1UL << PG_mlocked)
834 #define __PG_MLOCKED 0
838 * Flags checked when a page is freed. Pages being freed should not have
839 * these flags set. It they are, there is a problem.
841 #define PAGE_FLAGS_CHECK_AT_FREE \
842 (1UL << PG_lru | 1UL << PG_locked | \
843 1UL << PG_private | 1UL << PG_private_2 | \
844 1UL << PG_writeback | 1UL << PG_reserved | \
845 1UL << PG_slab | 1UL << PG_active | \
846 1UL << PG_unevictable | __PG_MLOCKED)
849 * Flags checked when a page is prepped for return by the page allocator.
850 * Pages being prepped should not have these flags set. It they are set,
851 * there has been a kernel bug or struct page corruption.
853 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
854 * alloc-free cycle to prevent from reusing the page.
856 #define PAGE_FLAGS_CHECK_AT_PREP \
857 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
859 #define PAGE_FLAGS_PRIVATE \
860 (1UL << PG_private | 1UL << PG_private_2)
862 * page_has_private - Determine if page has private stuff
863 * @page: The page to be checked
865 * Determine if a page has private stuff, indicating that release routines
866 * should be invoked upon it.
868 static inline int page_has_private(struct page
*page
)
870 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
877 #undef PF_NO_COMPOUND
878 #endif /* !__GENERATING_BOUNDS_H */
880 #endif /* PAGE_FLAGS_H */