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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_uptodate tells whether the page's contents is valid. When a read
67 * completes, the page becomes uptodate, unless a disk I/O error happened.
69 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
70 * file-backed pagecache (see mm/vmscan.c).
72 * PG_error is set to indicate that an I/O error occurred on this page.
74 * PG_arch_1 is an architecture specific page state bit. The generic code
75 * guarantees that this bit is cleared for a page when it first is entered into
78 * PG_hwpoison indicates that a page got corrupted in hardware and contains
79 * data with incorrect ECC bits that triggered a machine check. Accessing is
80 * not safe since it may cause another machine check. Don't touch!
84 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
85 * locked- and dirty-page accounting.
87 * The page flags field is split into two parts, the main flags area
88 * which extends from the low bits upwards, and the fields area which
89 * extends from the high bits downwards.
91 * | FIELD | ... | FLAGS |
95 * The fields area is reserved for fields mapping zone, node (for NUMA) and
96 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
97 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
100 PG_locked
, /* Page is locked. Don't touch. */
107 PG_waiters
, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
110 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
113 PG_private
, /* If pagecache, has fs-private data */
114 PG_private_2
, /* If pagecache, has fs aux data */
115 PG_writeback
, /* Page is under writeback */
116 PG_head
, /* A head page */
117 PG_mappedtodisk
, /* Has blocks allocated on-disk */
118 PG_reclaim
, /* To be reclaimed asap */
119 PG_swapbacked
, /* Page is backed by RAM/swap */
120 PG_unevictable
, /* Page is "unevictable" */
122 PG_mlocked
, /* Page is vma mlocked */
124 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
125 PG_uncached
, /* Page has been mapped as uncached */
127 #ifdef CONFIG_MEMORY_FAILURE
128 PG_hwpoison
, /* hardware poisoned page. Don't touch */
130 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
137 PG_checked
= PG_owner_priv_1
,
140 PG_swapcache
= PG_owner_priv_1
, /* Swap page: swp_entry_t in private */
142 /* Two page bits are conscripted by FS-Cache to maintain local caching
143 * state. These bits are set on pages belonging to the netfs's inodes
144 * when those inodes are being locally cached.
146 PG_fscache
= PG_private_2
, /* page backed by cache */
149 /* Pinned in Xen as a read-only pagetable page. */
150 PG_pinned
= PG_owner_priv_1
,
151 /* Pinned as part of domain save (see xen_mm_pin_all()). */
152 PG_savepinned
= PG_dirty
,
153 /* Has a grant mapping of another (foreign) domain's page. */
154 PG_foreign
= PG_owner_priv_1
,
155 /* Remapped by swiotlb-xen. */
156 PG_xen_remapped
= PG_owner_priv_1
,
159 PG_slob_free
= PG_private
,
161 /* Compound pages. Stored in first tail page's flags */
162 PG_double_map
= PG_private_2
,
164 /* non-lru isolated movable page */
165 PG_isolated
= PG_reclaim
,
168 #ifndef __GENERATING_BOUNDS_H
170 struct page
; /* forward declaration */
172 static inline struct page
*compound_head(struct page
*page
)
174 unsigned long head
= READ_ONCE(page
->compound_head
);
176 if (unlikely(head
& 1))
177 return (struct page
*) (head
- 1);
181 static __always_inline
int PageTail(struct page
*page
)
183 return READ_ONCE(page
->compound_head
) & 1;
186 static __always_inline
int PageCompound(struct page
*page
)
188 return test_bit(PG_head
, &page
->flags
) || PageTail(page
);
191 #define PAGE_POISON_PATTERN -1l
192 static inline int PagePoisoned(const struct page
*page
)
194 return page
->flags
== PAGE_POISON_PATTERN
;
197 #ifdef CONFIG_DEBUG_VM
198 void page_init_poison(struct page
*page
, size_t size
);
200 static inline void page_init_poison(struct page
*page
, size_t size
)
206 * Page flags policies wrt compound pages
209 * check if this struct page poisoned/uninitialized
212 * the page flag is relevant for small, head and tail pages.
215 * for compound page all operations related to the page flag applied to
219 * for compound page, callers only ever operate on the head page.
222 * modifications of the page flag must be done on small or head pages,
223 * checks can be done on tail pages too.
226 * the page flag is not relevant for compound pages.
228 #define PF_POISONED_CHECK(page) ({ \
229 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
231 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
232 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
233 #define PF_ONLY_HEAD(page, enforce) ({ \
234 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
235 PF_POISONED_CHECK(page); })
236 #define PF_NO_TAIL(page, enforce) ({ \
237 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
238 PF_POISONED_CHECK(compound_head(page)); })
239 #define PF_NO_COMPOUND(page, enforce) ({ \
240 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
241 PF_POISONED_CHECK(page); })
244 * Macros to create function definitions for page flags
246 #define TESTPAGEFLAG(uname, lname, policy) \
247 static __always_inline int Page##uname(struct page *page) \
248 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
250 #define SETPAGEFLAG(uname, lname, policy) \
251 static __always_inline void SetPage##uname(struct page *page) \
252 { set_bit(PG_##lname, &policy(page, 1)->flags); }
254 #define CLEARPAGEFLAG(uname, lname, policy) \
255 static __always_inline void ClearPage##uname(struct page *page) \
256 { clear_bit(PG_##lname, &policy(page, 1)->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 TESTSETFLAG(uname, lname, policy) \
267 static __always_inline int TestSetPage##uname(struct page *page) \
268 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
270 #define TESTCLEARFLAG(uname, lname, policy) \
271 static __always_inline int TestClearPage##uname(struct page *page) \
272 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
274 #define PAGEFLAG(uname, lname, policy) \
275 TESTPAGEFLAG(uname, lname, policy) \
276 SETPAGEFLAG(uname, lname, policy) \
277 CLEARPAGEFLAG(uname, lname, policy)
279 #define __PAGEFLAG(uname, lname, policy) \
280 TESTPAGEFLAG(uname, lname, policy) \
281 __SETPAGEFLAG(uname, lname, policy) \
282 __CLEARPAGEFLAG(uname, lname, policy)
284 #define TESTSCFLAG(uname, lname, policy) \
285 TESTSETFLAG(uname, lname, policy) \
286 TESTCLEARFLAG(uname, lname, policy)
288 #define TESTPAGEFLAG_FALSE(uname) \
289 static inline int Page##uname(const struct page *page) { return 0; }
291 #define SETPAGEFLAG_NOOP(uname) \
292 static inline void SetPage##uname(struct page *page) { }
294 #define CLEARPAGEFLAG_NOOP(uname) \
295 static inline void ClearPage##uname(struct page *page) { }
297 #define __CLEARPAGEFLAG_NOOP(uname) \
298 static inline void __ClearPage##uname(struct page *page) { }
300 #define TESTSETFLAG_FALSE(uname) \
301 static inline int TestSetPage##uname(struct page *page) { return 0; }
303 #define TESTCLEARFLAG_FALSE(uname) \
304 static inline int TestClearPage##uname(struct page *page) { return 0; }
306 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
307 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
309 #define TESTSCFLAG_FALSE(uname) \
310 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
312 __PAGEFLAG(Locked
, locked
, PF_NO_TAIL
)
313 PAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
) __CLEARPAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
)
314 PAGEFLAG(Error
, error
, PF_NO_TAIL
) TESTCLEARFLAG(Error
, error
, PF_NO_TAIL
)
315 PAGEFLAG(Referenced
, referenced
, PF_HEAD
)
316 TESTCLEARFLAG(Referenced
, referenced
, PF_HEAD
)
317 __SETPAGEFLAG(Referenced
, referenced
, PF_HEAD
)
318 PAGEFLAG(Dirty
, dirty
, PF_HEAD
) TESTSCFLAG(Dirty
, dirty
, PF_HEAD
)
319 __CLEARPAGEFLAG(Dirty
, dirty
, PF_HEAD
)
320 PAGEFLAG(LRU
, lru
, PF_HEAD
) __CLEARPAGEFLAG(LRU
, lru
, PF_HEAD
)
321 PAGEFLAG(Active
, active
, PF_HEAD
) __CLEARPAGEFLAG(Active
, active
, PF_HEAD
)
322 TESTCLEARFLAG(Active
, active
, PF_HEAD
)
323 PAGEFLAG(Workingset
, workingset
, PF_HEAD
)
324 TESTCLEARFLAG(Workingset
, workingset
, PF_HEAD
)
325 __PAGEFLAG(Slab
, slab
, PF_NO_TAIL
)
326 __PAGEFLAG(SlobFree
, slob_free
, PF_NO_TAIL
)
327 PAGEFLAG(Checked
, checked
, PF_NO_COMPOUND
) /* Used by some filesystems */
330 PAGEFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
331 TESTSCFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
332 PAGEFLAG(SavePinned
, savepinned
, PF_NO_COMPOUND
);
333 PAGEFLAG(Foreign
, foreign
, PF_NO_COMPOUND
);
334 PAGEFLAG(XenRemapped
, xen_remapped
, PF_NO_COMPOUND
)
335 TESTCLEARFLAG(XenRemapped
, xen_remapped
, PF_NO_COMPOUND
)
337 PAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
338 __CLEARPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
339 __SETPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
340 PAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
341 __CLEARPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
342 __SETPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
345 * Private page markings that may be used by the filesystem that owns the page
346 * for its own purposes.
347 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
349 PAGEFLAG(Private
, private, PF_ANY
) __SETPAGEFLAG(Private
, private, PF_ANY
)
350 __CLEARPAGEFLAG(Private
, private, PF_ANY
)
351 PAGEFLAG(Private2
, private_2
, PF_ANY
) TESTSCFLAG(Private2
, private_2
, PF_ANY
)
352 PAGEFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
353 TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
356 * Only test-and-set exist for PG_writeback. The unconditional operators are
357 * risky: they bypass page accounting.
359 TESTPAGEFLAG(Writeback
, writeback
, PF_NO_TAIL
)
360 TESTSCFLAG(Writeback
, writeback
, PF_NO_TAIL
)
361 PAGEFLAG(MappedToDisk
, mappedtodisk
, PF_NO_TAIL
)
363 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
364 PAGEFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
365 TESTCLEARFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
366 PAGEFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
367 TESTCLEARFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
369 #ifdef CONFIG_HIGHMEM
371 * Must use a macro here due to header dependency issues. page_zone() is not
372 * available at this point.
374 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
376 PAGEFLAG_FALSE(HighMem
)
380 static __always_inline
int PageSwapCache(struct page
*page
)
382 #ifdef CONFIG_THP_SWAP
383 page
= compound_head(page
);
385 return PageSwapBacked(page
) && test_bit(PG_swapcache
, &page
->flags
);
388 SETPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
389 CLEARPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
391 PAGEFLAG_FALSE(SwapCache
)
394 PAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
395 __CLEARPAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
396 TESTCLEARFLAG(Unevictable
, unevictable
, PF_HEAD
)
399 PAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
400 __CLEARPAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
401 TESTSCFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
403 PAGEFLAG_FALSE(Mlocked
) __CLEARPAGEFLAG_NOOP(Mlocked
)
404 TESTSCFLAG_FALSE(Mlocked
)
407 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
408 PAGEFLAG(Uncached
, uncached
, PF_NO_COMPOUND
)
410 PAGEFLAG_FALSE(Uncached
)
413 #ifdef CONFIG_MEMORY_FAILURE
414 PAGEFLAG(HWPoison
, hwpoison
, PF_ANY
)
415 TESTSCFLAG(HWPoison
, hwpoison
, PF_ANY
)
416 #define __PG_HWPOISON (1UL << PG_hwpoison)
417 extern bool set_hwpoison_free_buddy_page(struct page
*page
);
419 PAGEFLAG_FALSE(HWPoison
)
420 static inline bool set_hwpoison_free_buddy_page(struct page
*page
)
424 #define __PG_HWPOISON 0
427 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
428 TESTPAGEFLAG(Young
, young
, PF_ANY
)
429 SETPAGEFLAG(Young
, young
, PF_ANY
)
430 TESTCLEARFLAG(Young
, young
, PF_ANY
)
431 PAGEFLAG(Idle
, idle
, PF_ANY
)
435 * On an anonymous page mapped into a user virtual memory area,
436 * page->mapping points to its anon_vma, not to a struct address_space;
437 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
439 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
440 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
441 * bit; and then page->mapping points, not to an anon_vma, but to a private
442 * structure which KSM associates with that merged page. See ksm.h.
444 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
445 * page and then page->mapping points a struct address_space.
447 * Please note that, confusingly, "page_mapping" refers to the inode
448 * address_space which maps the page from disk; whereas "page_mapped"
449 * refers to user virtual address space into which the page is mapped.
451 #define PAGE_MAPPING_ANON 0x1
452 #define PAGE_MAPPING_MOVABLE 0x2
453 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
454 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
456 static __always_inline
int PageMappingFlags(struct page
*page
)
458 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) != 0;
461 static __always_inline
int PageAnon(struct page
*page
)
463 page
= compound_head(page
);
464 return ((unsigned long)page
->mapping
& PAGE_MAPPING_ANON
) != 0;
467 static __always_inline
int __PageMovable(struct page
*page
)
469 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
470 PAGE_MAPPING_MOVABLE
;
475 * A KSM page is one of those write-protected "shared pages" or "merged pages"
476 * which KSM maps into multiple mms, wherever identical anonymous page content
477 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
478 * anon_vma, but to that page's node of the stable tree.
480 static __always_inline
int PageKsm(struct page
*page
)
482 page
= compound_head(page
);
483 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
487 TESTPAGEFLAG_FALSE(Ksm
)
490 u64
stable_page_flags(struct page
*page
);
492 static inline int PageUptodate(struct page
*page
)
495 page
= compound_head(page
);
496 ret
= test_bit(PG_uptodate
, &(page
)->flags
);
498 * Must ensure that the data we read out of the page is loaded
499 * _after_ we've loaded page->flags to check for PageUptodate.
500 * We can skip the barrier if the page is not uptodate, because
501 * we wouldn't be reading anything from it.
503 * See SetPageUptodate() for the other side of the story.
511 static __always_inline
void __SetPageUptodate(struct page
*page
)
513 VM_BUG_ON_PAGE(PageTail(page
), page
);
515 __set_bit(PG_uptodate
, &page
->flags
);
518 static __always_inline
void SetPageUptodate(struct page
*page
)
520 VM_BUG_ON_PAGE(PageTail(page
), page
);
522 * Memory barrier must be issued before setting the PG_uptodate bit,
523 * so that all previous stores issued in order to bring the page
524 * uptodate are actually visible before PageUptodate becomes true.
527 set_bit(PG_uptodate
, &page
->flags
);
530 CLEARPAGEFLAG(Uptodate
, uptodate
, PF_NO_TAIL
)
532 int test_clear_page_writeback(struct page
*page
);
533 int __test_set_page_writeback(struct page
*page
, bool keep_write
);
535 #define test_set_page_writeback(page) \
536 __test_set_page_writeback(page, false)
537 #define test_set_page_writeback_keepwrite(page) \
538 __test_set_page_writeback(page, true)
540 static inline void set_page_writeback(struct page
*page
)
542 test_set_page_writeback(page
);
545 static inline void set_page_writeback_keepwrite(struct page
*page
)
547 test_set_page_writeback_keepwrite(page
);
550 __PAGEFLAG(Head
, head
, PF_ANY
) CLEARPAGEFLAG(Head
, head
, PF_ANY
)
552 static __always_inline
void set_compound_head(struct page
*page
, struct page
*head
)
554 WRITE_ONCE(page
->compound_head
, (unsigned long)head
+ 1);
557 static __always_inline
void clear_compound_head(struct page
*page
)
559 WRITE_ONCE(page
->compound_head
, 0);
562 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
563 static inline void ClearPageCompound(struct page
*page
)
565 BUG_ON(!PageHead(page
));
570 #define PG_head_mask ((1UL << PG_head))
572 #ifdef CONFIG_HUGETLB_PAGE
573 int PageHuge(struct page
*page
);
574 int PageHeadHuge(struct page
*page
);
575 bool page_huge_active(struct page
*page
);
577 TESTPAGEFLAG_FALSE(Huge
)
578 TESTPAGEFLAG_FALSE(HeadHuge
)
580 static inline bool page_huge_active(struct page
*page
)
587 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
589 * PageHuge() only returns true for hugetlbfs pages, but not for
590 * normal or transparent huge pages.
592 * PageTransHuge() returns true for both transparent huge and
593 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
594 * called only in the core VM paths where hugetlbfs pages can't exist.
596 static inline int PageTransHuge(struct page
*page
)
598 VM_BUG_ON_PAGE(PageTail(page
), page
);
599 return PageHead(page
);
603 * PageTransCompound returns true for both transparent huge pages
604 * and hugetlbfs pages, so it should only be called when it's known
605 * that hugetlbfs pages aren't involved.
607 static inline int PageTransCompound(struct page
*page
)
609 return PageCompound(page
);
613 * PageTransCompoundMap is the same as PageTransCompound, but it also
614 * guarantees the primary MMU has the entire compound page mapped
615 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
616 * can also map the entire compound page. This allows the secondary
617 * MMUs to call get_user_pages() only once for each compound page and
618 * to immediately map the entire compound page with a single secondary
619 * MMU fault. If there will be a pmd split later, the secondary MMUs
620 * will get an update through the MMU notifier invalidation through
623 * Unlike PageTransCompound, this is safe to be called only while
624 * split_huge_pmd() cannot run from under us, like if protected by the
625 * MMU notifier, otherwise it may result in page->_mapcount check false
628 * We have to treat page cache THP differently since every subpage of it
629 * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE
630 * mapped in the current process so comparing subpage's _mapcount to
631 * compound_mapcount to filter out PTE mapped case.
633 static inline int PageTransCompoundMap(struct page
*page
)
637 if (!PageTransCompound(page
))
641 return atomic_read(&page
->_mapcount
) < 0;
643 head
= compound_head(page
);
644 /* File THP is PMD mapped and not PTE mapped */
645 return atomic_read(&page
->_mapcount
) ==
646 atomic_read(compound_mapcount_ptr(head
));
650 * PageTransTail returns true for both transparent huge pages
651 * and hugetlbfs pages, so it should only be called when it's known
652 * that hugetlbfs pages aren't involved.
654 static inline int PageTransTail(struct page
*page
)
656 return PageTail(page
);
660 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
663 * This is required for optimization of rmap operations for THP: we can postpone
664 * per small page mapcount accounting (and its overhead from atomic operations)
665 * until the first PMD split.
667 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
668 * by one. This reference will go away with last compound_mapcount.
670 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
672 static inline int PageDoubleMap(struct page
*page
)
674 return PageHead(page
) && test_bit(PG_double_map
, &page
[1].flags
);
677 static inline void SetPageDoubleMap(struct page
*page
)
679 VM_BUG_ON_PAGE(!PageHead(page
), page
);
680 set_bit(PG_double_map
, &page
[1].flags
);
683 static inline void ClearPageDoubleMap(struct page
*page
)
685 VM_BUG_ON_PAGE(!PageHead(page
), page
);
686 clear_bit(PG_double_map
, &page
[1].flags
);
688 static inline int TestSetPageDoubleMap(struct page
*page
)
690 VM_BUG_ON_PAGE(!PageHead(page
), page
);
691 return test_and_set_bit(PG_double_map
, &page
[1].flags
);
694 static inline int TestClearPageDoubleMap(struct page
*page
)
696 VM_BUG_ON_PAGE(!PageHead(page
), page
);
697 return test_and_clear_bit(PG_double_map
, &page
[1].flags
);
701 TESTPAGEFLAG_FALSE(TransHuge
)
702 TESTPAGEFLAG_FALSE(TransCompound
)
703 TESTPAGEFLAG_FALSE(TransCompoundMap
)
704 TESTPAGEFLAG_FALSE(TransTail
)
705 PAGEFLAG_FALSE(DoubleMap
)
706 TESTSETFLAG_FALSE(DoubleMap
)
707 TESTCLEARFLAG_FALSE(DoubleMap
)
711 * For pages that are never mapped to userspace (and aren't PageSlab),
712 * page_type may be used. Because it is initialised to -1, we invert the
713 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
714 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
715 * low bits so that an underflow or overflow of page_mapcount() won't be
716 * mistaken for a page type value.
719 #define PAGE_TYPE_BASE 0xf0000000
720 /* Reserve 0x0000007f to catch underflows of page_mapcount */
721 #define PAGE_MAPCOUNT_RESERVE -128
722 #define PG_buddy 0x00000080
723 #define PG_offline 0x00000100
724 #define PG_kmemcg 0x00000200
725 #define PG_table 0x00000400
726 #define PG_guard 0x00000800
728 #define PageType(page, flag) \
729 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
731 static inline int page_has_type(struct page
*page
)
733 return (int)page
->page_type
< PAGE_MAPCOUNT_RESERVE
;
736 #define PAGE_TYPE_OPS(uname, lname) \
737 static __always_inline int Page##uname(struct page *page) \
739 return PageType(page, PG_##lname); \
741 static __always_inline void __SetPage##uname(struct page *page) \
743 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
744 page->page_type &= ~PG_##lname; \
746 static __always_inline void __ClearPage##uname(struct page *page) \
748 VM_BUG_ON_PAGE(!Page##uname(page), page); \
749 page->page_type |= PG_##lname; \
753 * PageBuddy() indicates that the page is free and in the buddy system
754 * (see mm/page_alloc.c).
756 PAGE_TYPE_OPS(Buddy
, buddy
)
759 * PageOffline() indicates that the page is logically offline although the
760 * containing section is online. (e.g. inflated in a balloon driver or
761 * not onlined when onlining the section).
762 * The content of these pages is effectively stale. Such pages should not
763 * be touched (read/write/dump/save) except by their owner.
765 PAGE_TYPE_OPS(Offline
, offline
)
768 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
769 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
771 PAGE_TYPE_OPS(Kmemcg
, kmemcg
)
774 * Marks pages in use as page tables.
776 PAGE_TYPE_OPS(Table
, table
)
779 * Marks guardpages used with debug_pagealloc.
781 PAGE_TYPE_OPS(Guard
, guard
)
783 extern bool is_free_buddy_page(struct page
*page
);
785 __PAGEFLAG(Isolated
, isolated
, PF_ANY
);
788 * If network-based swap is enabled, sl*b must keep track of whether pages
789 * were allocated from pfmemalloc reserves.
791 static inline int PageSlabPfmemalloc(struct page
*page
)
793 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
794 return PageActive(page
);
797 static inline void SetPageSlabPfmemalloc(struct page
*page
)
799 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
803 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
805 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
806 __ClearPageActive(page
);
809 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
811 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
812 ClearPageActive(page
);
816 #define __PG_MLOCKED (1UL << PG_mlocked)
818 #define __PG_MLOCKED 0
822 * Flags checked when a page is freed. Pages being freed should not have
823 * these flags set. It they are, there is a problem.
825 #define PAGE_FLAGS_CHECK_AT_FREE \
826 (1UL << PG_lru | 1UL << PG_locked | \
827 1UL << PG_private | 1UL << PG_private_2 | \
828 1UL << PG_writeback | 1UL << PG_reserved | \
829 1UL << PG_slab | 1UL << PG_active | \
830 1UL << PG_unevictable | __PG_MLOCKED)
833 * Flags checked when a page is prepped for return by the page allocator.
834 * Pages being prepped should not have these flags set. It they are set,
835 * there has been a kernel bug or struct page corruption.
837 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
838 * alloc-free cycle to prevent from reusing the page.
840 #define PAGE_FLAGS_CHECK_AT_PREP \
841 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
843 #define PAGE_FLAGS_PRIVATE \
844 (1UL << PG_private | 1UL << PG_private_2)
846 * page_has_private - Determine if page has private stuff
847 * @page: The page to be checked
849 * Determine if a page has private stuff, indicating that release routines
850 * should be invoked upon it.
852 static inline int page_has_private(struct page
*page
)
854 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
861 #undef PF_NO_COMPOUND
862 #endif /* !__GENERATING_BOUNDS_H */
864 #endif /* PAGE_FLAGS_H */