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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Macros for manipulating and testing page->flags
3 */
4
5#ifndef PAGE_FLAGS_H
6#define PAGE_FLAGS_H
7
Andrew Mortonf886ed42006-06-23 02:03:06 -07008#include <linux/types.h>
Christoph Lameter9223b412008-04-28 02:12:48 -07009#ifndef __GENERATING_BOUNDS_H
Christoph Lameter6d777952007-05-06 14:49:40 -070010#include <linux/mm_types.h>
Christoph Lameter9223b412008-04-28 02:12:48 -070011#include <linux/bounds.h>
12#endif /* !__GENERATING_BOUNDS_H */
Andrew Mortonf886ed42006-06-23 02:03:06 -070013
Linus Torvalds1da177e2005-04-16 15:20:36 -070014/*
15 * Various page->flags bits:
16 *
17 * PG_reserved is set for special pages, which can never be swapped out. Some
18 * of them might not even exist (eg empty_bad_page)...
19 *
Nick Pigginda6052f2006-09-25 23:31:35 -070020 * The PG_private bitflag is set on pagecache pages if they contain filesystem
21 * specific data (which is normally at page->private). It can be used by
22 * private allocations for its own usage.
Linus Torvalds1da177e2005-04-16 15:20:36 -070023 *
Nick Pigginda6052f2006-09-25 23:31:35 -070024 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
25 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
26 * is set before writeback starts and cleared when it finishes.
27 *
28 * PG_locked also pins a page in pagecache, and blocks truncation of the file
29 * while it is held.
30 *
31 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
32 * to become unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 *
34 * PG_uptodate tells whether the page's contents is valid. When a read
35 * completes, the page becomes uptodate, unless a disk I/O error happened.
36 *
Nick Pigginda6052f2006-09-25 23:31:35 -070037 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
38 * file-backed pagecache (see mm/vmscan.c).
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 *
40 * PG_error is set to indicate that an I/O error occurred on this page.
41 *
42 * PG_arch_1 is an architecture specific page state bit. The generic code
43 * guarantees that this bit is cleared for a page when it first is entered into
44 * the page cache.
45 *
46 * PG_highmem pages are not permanently mapped into the kernel virtual address
47 * space, they need to be kmapped separately for doing IO on the pages. The
48 * struct page (these bits with information) are always mapped into kernel
49 * address space...
Nick Pigginda6052f2006-09-25 23:31:35 -070050 *
51 * PG_buddy is set to indicate that the page is free and in the buddy system
52 * (see mm/page_alloc.c).
53 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 */
55
56/*
57 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
Andy Whitcroft91fc8ab2006-04-10 22:53:01 -070058 * locked- and dirty-page accounting.
59 *
60 * The page flags field is split into two parts, the main flags area
61 * which extends from the low bits upwards, and the fields area which
62 * extends from the high bits downwards.
63 *
64 * | FIELD | ... | FLAGS |
Christoph Lameter9223b412008-04-28 02:12:48 -070065 * N-1 ^ 0
66 * (NR_PAGEFLAGS)
Andy Whitcroft91fc8ab2006-04-10 22:53:01 -070067 *
Christoph Lameter9223b412008-04-28 02:12:48 -070068 * The fields area is reserved for fields mapping zone, node (for NUMA) and
69 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
70 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 */
Christoph Lametere2683182008-04-28 02:12:47 -070072enum pageflags {
73 PG_locked, /* Page is locked. Don't touch. */
74 PG_error,
75 PG_referenced,
76 PG_uptodate,
77 PG_dirty,
78 PG_lru,
79 PG_active,
80 PG_slab,
81 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
Christoph Lametere2683182008-04-28 02:12:47 -070082 PG_arch_1,
83 PG_reserved,
84 PG_private, /* If pagecache, has fs-private data */
85 PG_writeback, /* Page is under writeback */
Christoph Lametere20b8cc2008-04-28 02:12:55 -070086#ifdef CONFIG_PAGEFLAGS_EXTENDED
87 PG_head, /* A head page */
88 PG_tail, /* A tail page */
89#else
Christoph Lametere2683182008-04-28 02:12:47 -070090 PG_compound, /* A compound page */
Christoph Lametere20b8cc2008-04-28 02:12:55 -070091#endif
Christoph Lametere2683182008-04-28 02:12:47 -070092 PG_swapcache, /* Swap page: swp_entry_t in private */
93 PG_mappedtodisk, /* Has blocks allocated on-disk */
94 PG_reclaim, /* To be reclaimed asap */
Christoph Lametere2683182008-04-28 02:12:47 -070095 PG_buddy, /* Page is free, on buddy lists */
Rik van Rielb2e18532008-10-18 20:26:30 -070096 PG_swapbacked, /* Page is backed by RAM/swap */
Lee Schermerhorn894bc312008-10-18 20:26:39 -070097#ifdef CONFIG_UNEVICTABLE_LRU
98 PG_unevictable, /* Page is "unevictable" */
Nick Pigginb291f002008-10-18 20:26:44 -070099 PG_mlocked, /* Page is vma mlocked */
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700100#endif
Christoph Lameter602c4d12008-04-28 02:12:52 -0700101#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
102 PG_uncached, /* Page has been mapped as uncached */
Andrew Mortonf886ed42006-06-23 02:03:06 -0700103#endif
Andy Whitcroft0cad47c2008-07-23 21:27:16 -0700104 __NR_PAGEFLAGS,
105
106 /* Filesystems */
107 PG_checked = PG_owner_priv_1,
108
109 /* XEN */
110 PG_pinned = PG_owner_priv_1,
111 PG_savepinned = PG_dirty,
Andy Whitcroft8a380822008-07-23 21:27:18 -0700112
Andy Whitcroft9023cb72008-07-23 21:27:19 -0700113 /* SLOB */
114 PG_slob_page = PG_active,
115 PG_slob_free = PG_private,
116
Andy Whitcroft8a380822008-07-23 21:27:18 -0700117 /* SLUB */
118 PG_slub_frozen = PG_active,
119 PG_slub_debug = PG_error,
Christoph Lametere2683182008-04-28 02:12:47 -0700120};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
Christoph Lameter9223b412008-04-28 02:12:48 -0700122#ifndef __GENERATING_BOUNDS_H
123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124/*
Christoph Lameterf94a62e2008-04-28 02:12:49 -0700125 * Macros to create function definitions for page flags
126 */
127#define TESTPAGEFLAG(uname, lname) \
128static inline int Page##uname(struct page *page) \
129 { return test_bit(PG_##lname, &page->flags); }
130
131#define SETPAGEFLAG(uname, lname) \
132static inline void SetPage##uname(struct page *page) \
133 { set_bit(PG_##lname, &page->flags); }
134
135#define CLEARPAGEFLAG(uname, lname) \
136static inline void ClearPage##uname(struct page *page) \
137 { clear_bit(PG_##lname, &page->flags); }
138
139#define __SETPAGEFLAG(uname, lname) \
140static inline void __SetPage##uname(struct page *page) \
141 { __set_bit(PG_##lname, &page->flags); }
142
143#define __CLEARPAGEFLAG(uname, lname) \
144static inline void __ClearPage##uname(struct page *page) \
145 { __clear_bit(PG_##lname, &page->flags); }
146
147#define TESTSETFLAG(uname, lname) \
148static inline int TestSetPage##uname(struct page *page) \
149 { return test_and_set_bit(PG_##lname, &page->flags); }
150
151#define TESTCLEARFLAG(uname, lname) \
152static inline int TestClearPage##uname(struct page *page) \
153 { return test_and_clear_bit(PG_##lname, &page->flags); }
154
155
156#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
157 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
158
159#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
160 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
161
Christoph Lameterec7cade2008-04-28 02:12:53 -0700162#define PAGEFLAG_FALSE(uname) \
163static inline int Page##uname(struct page *page) \
164 { return 0; }
165
Christoph Lameterf94a62e2008-04-28 02:12:49 -0700166#define TESTSCFLAG(uname, lname) \
167 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
168
Lee Schermerhorn8a7a8542008-10-18 20:26:37 -0700169#define SETPAGEFLAG_NOOP(uname) \
170static inline void SetPage##uname(struct page *page) { }
171
172#define CLEARPAGEFLAG_NOOP(uname) \
173static inline void ClearPage##uname(struct page *page) { }
174
175#define __CLEARPAGEFLAG_NOOP(uname) \
176static inline void __ClearPage##uname(struct page *page) { }
177
178#define TESTCLEARFLAG_FALSE(uname) \
179static inline int TestClearPage##uname(struct page *page) { return 0; }
180
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700181struct page; /* forward declaration */
182
Nick Piggin529ae9a2008-08-02 12:01:03 +0200183TESTPAGEFLAG(Locked, locked)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700184PAGEFLAG(Error, error)
185PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
186PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
187PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
188PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700189 TESTCLEARFLAG(Active, active)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700190__PAGEFLAG(Slab, slab)
Andy Whitcroft0cad47c2008-07-23 21:27:16 -0700191PAGEFLAG(Checked, checked) /* Used by some filesystems */
192PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
193PAGEFLAG(SavePinned, savepinned); /* Xen */
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700194PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
195PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
196 __SETPAGEFLAG(Private, private)
Rik van Rielb2e18532008-10-18 20:26:30 -0700197PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700198
Andy Whitcroft9023cb72008-07-23 21:27:19 -0700199__PAGEFLAG(SlobPage, slob_page)
200__PAGEFLAG(SlobFree, slob_free)
201
Andy Whitcroft8a380822008-07-23 21:27:18 -0700202__PAGEFLAG(SlubFrozen, slub_frozen)
203__PAGEFLAG(SlubDebug, slub_debug)
204
Christoph Lameterf94a62e2008-04-28 02:12:49 -0700205/*
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700206 * Only test-and-set exist for PG_writeback. The unconditional operators are
207 * risky: they bypass page accounting.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 */
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700209TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
210__PAGEFLAG(Buddy, buddy)
211PAGEFLAG(MappedToDisk, mappedtodisk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700213/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
214PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
Christoph Lameter0a128b22008-04-28 02:12:52 -0700215PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700217#ifdef CONFIG_HIGHMEM
218/*
219 * Must use a macro here due to header dependency issues. page_zone() is not
220 * available at this point.
221 */
Christoph Lameter0a128b22008-04-28 02:12:52 -0700222#define PageHighMem(__p) is_highmem(page_zone(__p))
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700223#else
Christoph Lameterec7cade2008-04-28 02:12:53 -0700224PAGEFLAG_FALSE(HighMem)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700225#endif
226
227#ifdef CONFIG_SWAP
228PAGEFLAG(SwapCache, swapcache)
229#else
Christoph Lameterec7cade2008-04-28 02:12:53 -0700230PAGEFLAG_FALSE(SwapCache)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700231#endif
232
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700233#ifdef CONFIG_UNEVICTABLE_LRU
234PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
235 TESTCLEARFLAG(Unevictable, unevictable)
Nick Pigginb291f002008-10-18 20:26:44 -0700236
237#define MLOCK_PAGES 1
238PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
239 TESTSCFLAG(Mlocked, mlocked)
240
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700241#else
Nick Pigginb291f002008-10-18 20:26:44 -0700242
243#define MLOCK_PAGES 0
244PAGEFLAG_FALSE(Mlocked)
245 SETPAGEFLAG_NOOP(Mlocked) TESTCLEARFLAG_FALSE(Mlocked)
246
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700247PAGEFLAG_FALSE(Unevictable) TESTCLEARFLAG_FALSE(Unevictable)
248 SETPAGEFLAG_NOOP(Unevictable) CLEARPAGEFLAG_NOOP(Unevictable)
249 __CLEARPAGEFLAG_NOOP(Unevictable)
250#endif
251
Christoph Lameter602c4d12008-04-28 02:12:52 -0700252#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700253PAGEFLAG(Uncached, uncached)
Christoph Lameter602c4d12008-04-28 02:12:52 -0700254#else
Christoph Lameterec7cade2008-04-28 02:12:53 -0700255PAGEFLAG_FALSE(Uncached)
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700256#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257
Nick Piggin0ed361d2008-02-04 22:29:34 -0800258static inline int PageUptodate(struct page *page)
259{
260 int ret = test_bit(PG_uptodate, &(page)->flags);
261
262 /*
263 * Must ensure that the data we read out of the page is loaded
264 * _after_ we've loaded page->flags to check for PageUptodate.
265 * We can skip the barrier if the page is not uptodate, because
266 * we wouldn't be reading anything from it.
267 *
268 * See SetPageUptodate() for the other side of the story.
269 */
270 if (ret)
271 smp_rmb();
272
273 return ret;
274}
275
276static inline void __SetPageUptodate(struct page *page)
277{
278 smp_wmb();
279 __set_bit(PG_uptodate, &(page)->flags);
Nick Piggin0ed361d2008-02-04 22:29:34 -0800280}
281
Heiko Carstens2dcea572006-09-29 01:58:41 -0700282static inline void SetPageUptodate(struct page *page)
283{
Nick Piggin0ed361d2008-02-04 22:29:34 -0800284#ifdef CONFIG_S390
Heiko Carstens2dcea572006-09-29 01:58:41 -0700285 if (!test_and_set_bit(PG_uptodate, &page->flags))
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200286 page_clear_dirty(page);
Christoph Lameterf6ac2352006-06-30 01:55:32 -0700287#else
Nick Piggin0ed361d2008-02-04 22:29:34 -0800288 /*
289 * Memory barrier must be issued before setting the PG_uptodate bit,
290 * so that all previous stores issued in order to bring the page
291 * uptodate are actually visible before PageUptodate becomes true.
292 *
293 * s390 doesn't need an explicit smp_wmb here because the test and
294 * set bit already provides full barriers.
295 */
296 smp_wmb();
297 set_bit(PG_uptodate, &(page)->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298#endif
Nick Piggin0ed361d2008-02-04 22:29:34 -0800299}
300
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700301CLEARPAGEFLAG(Uptodate, uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302
Linus Torvaldsfba25912006-12-20 13:46:42 -0800303extern void cancel_dirty_page(struct page *page, unsigned int account_size);
304
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305int test_clear_page_writeback(struct page *page);
306int test_set_page_writeback(struct page *page);
307
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308static inline void set_page_writeback(struct page *page)
309{
310 test_set_page_writeback(page);
311}
312
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700313#ifdef CONFIG_PAGEFLAGS_EXTENDED
314/*
315 * System with lots of page flags available. This allows separate
316 * flags for PageHead() and PageTail() checks of compound pages so that bit
317 * tests can be used in performance sensitive paths. PageCompound is
318 * generally not used in hot code paths.
319 */
320__PAGEFLAG(Head, head)
321__PAGEFLAG(Tail, tail)
322
323static inline int PageCompound(struct page *page)
324{
325 return page->flags & ((1L << PG_head) | (1L << PG_tail));
326
327}
328#else
329/*
330 * Reduce page flag use as much as possible by overlapping
331 * compound page flags with the flags used for page cache pages. Possible
332 * because PageCompound is always set for compound pages and not for
333 * pages on the LRU and/or pagecache.
334 */
Christoph Lameter6a1e7f72008-04-28 02:12:50 -0700335TESTPAGEFLAG(Compound, compound)
336__PAGEFLAG(Head, compound)
337
338/*
339 * PG_reclaim is used in combination with PG_compound to mark the
340 * head and tail of a compound page. This saves one page flag
341 * but makes it impossible to use compound pages for the page cache.
342 * The PG_reclaim bit would have to be used for reclaim or readahead
343 * if compound pages enter the page cache.
344 *
345 * PG_compound & PG_reclaim => Tail page
346 * PG_compound & ~PG_reclaim => Head page
347 */
348#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
349
350static inline int PageTail(struct page *page)
351{
352 return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
353}
354
355static inline void __SetPageTail(struct page *page)
356{
357 page->flags |= PG_head_tail_mask;
358}
359
360static inline void __ClearPageTail(struct page *page)
361{
362 page->flags &= ~PG_head_tail_mask;
363}
364
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700365#endif /* !PAGEFLAGS_EXTENDED */
Russ Andersondfa7e202008-06-09 11:18:45 -0500366
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700367#ifdef CONFIG_UNEVICTABLE_LRU
Nick Pigginb291f002008-10-18 20:26:44 -0700368#define __PG_UNEVICTABLE (1 << PG_unevictable)
369#define __PG_MLOCKED (1 << PG_mlocked)
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700370#else
Nick Pigginb291f002008-10-18 20:26:44 -0700371#define __PG_UNEVICTABLE 0
372#define __PG_MLOCKED 0
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700373#endif
374
Russ Andersondfa7e202008-06-09 11:18:45 -0500375#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
376 1 << PG_buddy | 1 << PG_writeback | \
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700377 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
Nick Pigginb291f002008-10-18 20:26:44 -0700378 __PG_UNEVICTABLE | __PG_MLOCKED)
Russ Andersondfa7e202008-06-09 11:18:45 -0500379
380/*
381 * Flags checked in bad_page(). Pages on the free list should not have
382 * these flags set. It they are, there is a problem.
383 */
Rik van Rielb2e18532008-10-18 20:26:30 -0700384#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | \
385 1 << PG_reclaim | 1 << PG_dirty | 1 << PG_swapbacked)
Russ Andersondfa7e202008-06-09 11:18:45 -0500386
387/*
388 * Flags checked when a page is freed. Pages being freed should not have
389 * these flags set. It they are, there is a problem.
390 */
391#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved)
392
393/*
394 * Flags checked when a page is prepped for return by the page allocator.
395 * Pages being prepped should not have these flags set. It they are, there
396 * is a problem.
397 */
Rik van Rielb2e18532008-10-18 20:26:30 -0700398#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \
399 1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked)
Russ Andersondfa7e202008-06-09 11:18:45 -0500400
Christoph Lameter9223b412008-04-28 02:12:48 -0700401#endif /* !__GENERATING_BOUNDS_H */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402#endif /* PAGE_FLAGS_H */