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 __SETPAGEFLAG(Referenced, referenced)
202 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
203 PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
204 PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
205 TESTCLEARFLAG(Active, active)
206 __PAGEFLAG(Slab, slab)
207 PAGEFLAG(Checked, checked) /* Used by some filesystems */
208 PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
209 PAGEFLAG(SavePinned, savepinned); /* Xen */
210 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
211 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
212 __SETPAGEFLAG(SwapBacked, swapbacked)
214 __PAGEFLAG(SlobFree, slob_free)
217 * Private page markings that may be used by the filesystem that owns the page
218 * for its own purposes.
219 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
221 PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
222 __CLEARPAGEFLAG(Private, private)
223 PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
224 PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
227 * Only test-and-set exist for PG_writeback. The unconditional operators are
228 * risky: they bypass page accounting.
230 TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
231 PAGEFLAG(MappedToDisk, mappedtodisk)
233 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
234 PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
235 PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)
237 #ifdef CONFIG_HIGHMEM
239 * Must use a macro here due to header dependency issues. page_zone() is not
240 * available at this point.
242 #define PageHighMem(__p) is_highmem(page_zone(__p))
244 PAGEFLAG_FALSE(HighMem)
248 PAGEFLAG(SwapCache, swapcache)
250 PAGEFLAG_FALSE(SwapCache)
251 SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache)
254 PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
255 TESTCLEARFLAG(Unevictable, unevictable)
258 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
259 TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
261 PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked)
262 TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
265 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
266 PAGEFLAG(Uncached, uncached)
268 PAGEFLAG_FALSE(Uncached)
271 #ifdef CONFIG_MEMORY_FAILURE
272 PAGEFLAG(HWPoison, hwpoison)
273 TESTSCFLAG(HWPoison, hwpoison)
274 #define __PG_HWPOISON (1UL << PG_hwpoison)
276 PAGEFLAG_FALSE(HWPoison)
277 #define __PG_HWPOISON 0
280 u64 stable_page_flags(struct page *page);
282 static inline int PageUptodate(struct page *page)
284 int ret = test_bit(PG_uptodate, &(page)->flags);
287 * Must ensure that the data we read out of the page is loaded
288 * _after_ we've loaded page->flags to check for PageUptodate.
289 * We can skip the barrier if the page is not uptodate, because
290 * we wouldn't be reading anything from it.
292 * See SetPageUptodate() for the other side of the story.
300 static inline void __SetPageUptodate(struct page *page)
303 __set_bit(PG_uptodate, &(page)->flags);
306 static inline void SetPageUptodate(struct page *page)
309 * Memory barrier must be issued before setting the PG_uptodate bit,
310 * so that all previous stores issued in order to bring the page
311 * uptodate are actually visible before PageUptodate becomes true.
314 set_bit(PG_uptodate, &(page)->flags);
317 CLEARPAGEFLAG(Uptodate, uptodate)
319 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
321 int test_clear_page_writeback(struct page *page);
322 int __test_set_page_writeback(struct page *page, bool keep_write);
324 #define test_set_page_writeback(page) \
325 __test_set_page_writeback(page, false)
326 #define test_set_page_writeback_keepwrite(page) \
327 __test_set_page_writeback(page, true)
329 static inline void set_page_writeback(struct page *page)
331 test_set_page_writeback(page);
334 static inline void set_page_writeback_keepwrite(struct page *page)
336 test_set_page_writeback_keepwrite(page);
339 #ifdef CONFIG_PAGEFLAGS_EXTENDED
341 * System with lots of page flags available. This allows separate
342 * flags for PageHead() and PageTail() checks of compound pages so that bit
343 * tests can be used in performance sensitive paths. PageCompound is
344 * generally not used in hot code paths except arch/powerpc/mm/init_64.c
345 * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
346 * and avoid handling those in real mode.
348 __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head)
349 __PAGEFLAG(Tail, tail)
351 static inline int PageCompound(struct page *page)
353 return page->flags & ((1L << PG_head) | (1L << PG_tail));
356 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
357 static inline void ClearPageCompound(struct page *page)
359 BUG_ON(!PageHead(page));
364 #define PG_head_mask ((1L << PG_head))
368 * Reduce page flag use as much as possible by overlapping
369 * compound page flags with the flags used for page cache pages. Possible
370 * because PageCompound is always set for compound pages and not for
371 * pages on the LRU and/or pagecache.
373 TESTPAGEFLAG(Compound, compound)
374 __SETPAGEFLAG(Head, compound) __CLEARPAGEFLAG(Head, compound)
377 * PG_reclaim is used in combination with PG_compound to mark the
378 * head and tail of a compound page. This saves one page flag
379 * but makes it impossible to use compound pages for the page cache.
380 * The PG_reclaim bit would have to be used for reclaim or readahead
381 * if compound pages enter the page cache.
383 * PG_compound & PG_reclaim => Tail page
384 * PG_compound & ~PG_reclaim => Head page
386 #define PG_head_mask ((1L << PG_compound))
387 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
389 static inline int PageHead(struct page *page)
391 return ((page->flags & PG_head_tail_mask) == PG_head_mask);
394 static inline int PageTail(struct page *page)
396 return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
399 static inline void __SetPageTail(struct page *page)
401 page->flags |= PG_head_tail_mask;
404 static inline void __ClearPageTail(struct page *page)
406 page->flags &= ~PG_head_tail_mask;
409 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
410 static inline void ClearPageCompound(struct page *page)
412 BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound));
413 clear_bit(PG_compound, &page->flags);
417 #endif /* !PAGEFLAGS_EXTENDED */
419 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
421 * PageHuge() only returns true for hugetlbfs pages, but not for
422 * normal or transparent huge pages.
424 * PageTransHuge() returns true for both transparent huge and
425 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
426 * called only in the core VM paths where hugetlbfs pages can't exist.
428 static inline int PageTransHuge(struct page *page)
430 VM_BUG_ON_PAGE(PageTail(page), page);
431 return PageHead(page);
435 * PageTransCompound returns true for both transparent huge pages
436 * and hugetlbfs pages, so it should only be called when it's known
437 * that hugetlbfs pages aren't involved.
439 static inline int PageTransCompound(struct page *page)
441 return PageCompound(page);
445 * PageTransTail returns true for both transparent huge pages
446 * and hugetlbfs pages, so it should only be called when it's known
447 * that hugetlbfs pages aren't involved.
449 static inline int PageTransTail(struct page *page)
451 return PageTail(page);
456 static inline int PageTransHuge(struct page *page)
461 static inline int PageTransCompound(struct page *page)
466 static inline int PageTransTail(struct page *page)
473 * If network-based swap is enabled, sl*b must keep track of whether pages
474 * were allocated from pfmemalloc reserves.
476 static inline int PageSlabPfmemalloc(struct page *page)
478 VM_BUG_ON_PAGE(!PageSlab(page), page);
479 return PageActive(page);
482 static inline void SetPageSlabPfmemalloc(struct page *page)
484 VM_BUG_ON_PAGE(!PageSlab(page), page);
488 static inline void __ClearPageSlabPfmemalloc(struct page *page)
490 VM_BUG_ON_PAGE(!PageSlab(page), page);
491 __ClearPageActive(page);
494 static inline void ClearPageSlabPfmemalloc(struct page *page)
496 VM_BUG_ON_PAGE(!PageSlab(page), page);
497 ClearPageActive(page);
501 #define __PG_MLOCKED (1 << PG_mlocked)
503 #define __PG_MLOCKED 0
506 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
507 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
509 #define __PG_COMPOUND_LOCK 0
513 * Flags checked when a page is freed. Pages being freed should not have
514 * these flags set. It they are, there is a problem.
516 #define PAGE_FLAGS_CHECK_AT_FREE \
517 (1 << PG_lru | 1 << PG_locked | \
518 1 << PG_private | 1 << PG_private_2 | \
519 1 << PG_writeback | 1 << PG_reserved | \
520 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
521 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
525 * Flags checked when a page is prepped for return by the page allocator.
526 * Pages being prepped should not have any flags set. It they are set,
527 * there has been a kernel bug or struct page corruption.
529 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
531 #define PAGE_FLAGS_PRIVATE \
532 (1 << PG_private | 1 << PG_private_2)
534 * page_has_private - Determine if page has private stuff
535 * @page: The page to be checked
537 * Determine if a page has private stuff, indicating that release routines
538 * should be invoked upon it.
540 static inline int page_has_private(struct page *page)
542 return !!(page->flags & PAGE_FLAGS_PRIVATE);
545 #endif /* !__GENERATING_BOUNDS_H */
547 #endif /* PAGE_FLAGS_H */