2 * Macros for manipulating and testing page->flags
8 #include <linux/types.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 */
17 * Various page->flags bits:
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)...
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.
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.
30 * PG_locked also pins a page in pagecache, and blocks truncation of the file
33 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
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.
39 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
40 * file-backed pagecache (see mm/vmscan.c).
42 * PG_error is set to indicate that an I/O error occurred on this page.
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
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
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!
59 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
60 * locked- and dirty-page accounting.
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.
66 * | FIELD | ... | FLAGS |
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).
75 PG_locked, /* Page is locked. Don't touch. */
83 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
86 PG_private, /* If pagecache, has fs-private data */
87 PG_private_2, /* If pagecache, has fs aux data */
88 PG_writeback, /* Page is under writeback */
89 #ifdef CONFIG_PAGEFLAGS_EXTENDED
90 PG_head, /* A head page */
91 PG_tail, /* A tail page */
93 PG_compound, /* A compound page */
95 PG_swapcache, /* Swap page: swp_entry_t in private */
96 PG_mappedtodisk, /* Has blocks allocated on-disk */
97 PG_reclaim, /* To be reclaimed asap */
98 PG_swapbacked, /* Page is backed by RAM/swap */
99 PG_unevictable, /* Page is "unevictable" */
101 PG_mlocked, /* Page is vma mlocked */
103 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
104 PG_uncached, /* Page has been mapped as uncached */
106 #ifdef CONFIG_MEMORY_FAILURE
107 PG_hwpoison, /* hardware poisoned page. Don't touch */
109 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
115 PG_checked = PG_owner_priv_1,
117 /* Two page bits are conscripted by FS-Cache to maintain local caching
118 * state. These bits are set on pages belonging to the netfs's inodes
119 * when those inodes are being locally cached.
121 PG_fscache = PG_private_2, /* page backed by cache */
124 PG_pinned = PG_owner_priv_1,
125 PG_savepinned = PG_dirty,
128 PG_slob_free = PG_private,
131 #ifndef __GENERATING_BOUNDS_H
134 * Macros to create function definitions for page flags
136 #define TESTPAGEFLAG(uname, lname) \
137 static inline int Page##uname(const struct page *page) \
138 { return test_bit(PG_##lname, &page->flags); }
140 #define SETPAGEFLAG(uname, lname) \
141 static inline void SetPage##uname(struct page *page) \
142 { set_bit(PG_##lname, &page->flags); }
144 #define CLEARPAGEFLAG(uname, lname) \
145 static inline void ClearPage##uname(struct page *page) \
146 { clear_bit(PG_##lname, &page->flags); }
148 #define __SETPAGEFLAG(uname, lname) \
149 static inline void __SetPage##uname(struct page *page) \
150 { __set_bit(PG_##lname, &page->flags); }
152 #define __CLEARPAGEFLAG(uname, lname) \
153 static inline void __ClearPage##uname(struct page *page) \
154 { __clear_bit(PG_##lname, &page->flags); }
156 #define TESTSETFLAG(uname, lname) \
157 static inline int TestSetPage##uname(struct page *page) \
158 { return test_and_set_bit(PG_##lname, &page->flags); }
160 #define TESTCLEARFLAG(uname, lname) \
161 static inline int TestClearPage##uname(struct page *page) \
162 { return test_and_clear_bit(PG_##lname, &page->flags); }
164 #define __TESTCLEARFLAG(uname, lname) \
165 static inline int __TestClearPage##uname(struct page *page) \
166 { return __test_and_clear_bit(PG_##lname, &page->flags); }
168 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
169 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
171 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
172 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
174 #define PAGEFLAG_FALSE(uname) \
175 static inline int Page##uname(const struct page *page) \
178 #define TESTSCFLAG(uname, lname) \
179 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
181 #define SETPAGEFLAG_NOOP(uname) \
182 static inline void SetPage##uname(struct page *page) { }
184 #define CLEARPAGEFLAG_NOOP(uname) \
185 static inline void ClearPage##uname(struct page *page) { }
187 #define __CLEARPAGEFLAG_NOOP(uname) \
188 static inline void __ClearPage##uname(struct page *page) { }
190 #define TESTCLEARFLAG_FALSE(uname) \
191 static inline int TestClearPage##uname(struct page *page) { return 0; }
193 #define __TESTCLEARFLAG_FALSE(uname) \
194 static inline int __TestClearPage##uname(struct page *page) { return 0; }
196 struct page; /* forward declaration */
198 TESTPAGEFLAG(Locked, locked)
199 PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
200 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
201 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
202 PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
203 PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
204 TESTCLEARFLAG(Active, active)
205 __PAGEFLAG(Slab, slab)
206 PAGEFLAG(Checked, checked) /* Used by some filesystems */
207 PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
208 PAGEFLAG(SavePinned, savepinned); /* Xen */
209 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
210 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
211 __SETPAGEFLAG(SwapBacked, swapbacked)
213 __PAGEFLAG(SlobFree, slob_free)
216 * Private page markings that may be used by the filesystem that owns the page
217 * for its own purposes.
218 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
220 PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
221 __CLEARPAGEFLAG(Private, private)
222 PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
223 PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
226 * Only test-and-set exist for PG_writeback. The unconditional operators are
227 * risky: they bypass page accounting.
229 TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
230 PAGEFLAG(MappedToDisk, mappedtodisk)
232 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
233 PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
234 PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)
236 #ifdef CONFIG_HIGHMEM
238 * Must use a macro here due to header dependency issues. page_zone() is not
239 * available at this point.
241 #define PageHighMem(__p) is_highmem(page_zone(__p))
243 PAGEFLAG_FALSE(HighMem)
247 PAGEFLAG(SwapCache, swapcache)
249 PAGEFLAG_FALSE(SwapCache)
250 SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache)
253 PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
254 TESTCLEARFLAG(Unevictable, unevictable)
257 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
258 TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
260 PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked)
261 TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
264 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
265 PAGEFLAG(Uncached, uncached)
267 PAGEFLAG_FALSE(Uncached)
270 #ifdef CONFIG_MEMORY_FAILURE
271 PAGEFLAG(HWPoison, hwpoison)
272 TESTSCFLAG(HWPoison, hwpoison)
273 #define __PG_HWPOISON (1UL << PG_hwpoison)
275 PAGEFLAG_FALSE(HWPoison)
276 #define __PG_HWPOISON 0
279 u64 stable_page_flags(struct page *page);
281 static inline int PageUptodate(struct page *page)
283 int ret = test_bit(PG_uptodate, &(page)->flags);
286 * Must ensure that the data we read out of the page is loaded
287 * _after_ we've loaded page->flags to check for PageUptodate.
288 * We can skip the barrier if the page is not uptodate, because
289 * we wouldn't be reading anything from it.
291 * See SetPageUptodate() for the other side of the story.
299 static inline void __SetPageUptodate(struct page *page)
302 __set_bit(PG_uptodate, &(page)->flags);
305 static inline void SetPageUptodate(struct page *page)
308 * Memory barrier must be issued before setting the PG_uptodate bit,
309 * so that all previous stores issued in order to bring the page
310 * uptodate are actually visible before PageUptodate becomes true.
313 set_bit(PG_uptodate, &(page)->flags);
316 CLEARPAGEFLAG(Uptodate, uptodate)
318 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
320 int test_clear_page_writeback(struct page *page);
321 int test_set_page_writeback(struct page *page);
323 static inline void set_page_writeback(struct page *page)
325 test_set_page_writeback(page);
328 #ifdef CONFIG_PAGEFLAGS_EXTENDED
330 * System with lots of page flags available. This allows separate
331 * flags for PageHead() and PageTail() checks of compound pages so that bit
332 * tests can be used in performance sensitive paths. PageCompound is
333 * generally not used in hot code paths except arch/powerpc/mm/init_64.c
334 * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
335 * and avoid handling those in real mode.
337 __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head)
338 __PAGEFLAG(Tail, tail)
340 static inline int PageCompound(struct page *page)
342 return page->flags & ((1L << PG_head) | (1L << PG_tail));
345 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
346 static inline void ClearPageCompound(struct page *page)
348 BUG_ON(!PageHead(page));
354 * Reduce page flag use as much as possible by overlapping
355 * compound page flags with the flags used for page cache pages. Possible
356 * because PageCompound is always set for compound pages and not for
357 * pages on the LRU and/or pagecache.
359 TESTPAGEFLAG(Compound, compound)
360 __SETPAGEFLAG(Head, compound) __CLEARPAGEFLAG(Head, compound)
363 * PG_reclaim is used in combination with PG_compound to mark the
364 * head and tail of a compound page. This saves one page flag
365 * but makes it impossible to use compound pages for the page cache.
366 * The PG_reclaim bit would have to be used for reclaim or readahead
367 * if compound pages enter the page cache.
369 * PG_compound & PG_reclaim => Tail page
370 * PG_compound & ~PG_reclaim => Head page
372 #define PG_head_mask ((1L << PG_compound))
373 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
375 static inline int PageHead(struct page *page)
377 return ((page->flags & PG_head_tail_mask) == PG_head_mask);
380 static inline int PageTail(struct page *page)
382 return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
385 static inline void __SetPageTail(struct page *page)
387 page->flags |= PG_head_tail_mask;
390 static inline void __ClearPageTail(struct page *page)
392 page->flags &= ~PG_head_tail_mask;
395 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
396 static inline void ClearPageCompound(struct page *page)
398 BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound));
399 clear_bit(PG_compound, &page->flags);
403 #endif /* !PAGEFLAGS_EXTENDED */
405 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
407 * PageHuge() only returns true for hugetlbfs pages, but not for
408 * normal or transparent huge pages.
410 * PageTransHuge() returns true for both transparent huge and
411 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
412 * called only in the core VM paths where hugetlbfs pages can't exist.
414 static inline int PageTransHuge(struct page *page)
416 VM_BUG_ON_PAGE(PageTail(page), page);
417 return PageHead(page);
421 * PageTransCompound returns true for both transparent huge pages
422 * and hugetlbfs pages, so it should only be called when it's known
423 * that hugetlbfs pages aren't involved.
425 static inline int PageTransCompound(struct page *page)
427 return PageCompound(page);
431 * PageTransTail returns true for both transparent huge pages
432 * and hugetlbfs pages, so it should only be called when it's known
433 * that hugetlbfs pages aren't involved.
435 static inline int PageTransTail(struct page *page)
437 return PageTail(page);
442 static inline int PageTransHuge(struct page *page)
447 static inline int PageTransCompound(struct page *page)
452 static inline int PageTransTail(struct page *page)
459 * If network-based swap is enabled, sl*b must keep track of whether pages
460 * were allocated from pfmemalloc reserves.
462 static inline int PageSlabPfmemalloc(struct page *page)
464 VM_BUG_ON_PAGE(!PageSlab(page), page);
465 return PageActive(page);
468 static inline void SetPageSlabPfmemalloc(struct page *page)
470 VM_BUG_ON_PAGE(!PageSlab(page), page);
474 static inline void __ClearPageSlabPfmemalloc(struct page *page)
476 VM_BUG_ON_PAGE(!PageSlab(page), page);
477 __ClearPageActive(page);
480 static inline void ClearPageSlabPfmemalloc(struct page *page)
482 VM_BUG_ON_PAGE(!PageSlab(page), page);
483 ClearPageActive(page);
487 #define __PG_MLOCKED (1 << PG_mlocked)
489 #define __PG_MLOCKED 0
492 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
493 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
495 #define __PG_COMPOUND_LOCK 0
499 * Flags checked when a page is freed. Pages being freed should not have
500 * these flags set. It they are, there is a problem.
502 #define PAGE_FLAGS_CHECK_AT_FREE \
503 (1 << PG_lru | 1 << PG_locked | \
504 1 << PG_private | 1 << PG_private_2 | \
505 1 << PG_writeback | 1 << PG_reserved | \
506 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
507 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
511 * Flags checked when a page is prepped for return by the page allocator.
512 * Pages being prepped should not have any flags set. It they are set,
513 * there has been a kernel bug or struct page corruption.
515 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
517 #define PAGE_FLAGS_PRIVATE \
518 (1 << PG_private | 1 << PG_private_2)
520 * page_has_private - Determine if page has private stuff
521 * @page: The page to be checked
523 * Determine if a page has private stuff, indicating that release routines
524 * should be invoked upon it.
526 static inline int page_has_private(struct page *page)
528 return !!(page->flags & PAGE_FLAGS_PRIVATE);
531 #endif /* !__GENERATING_BOUNDS_H */
533 #endif /* PAGE_FLAGS_H */