xref: /freebsd/sys/vm/vm_page.h (revision 48c5129f93c5eb5419c87b08e4677d51513f1dc0)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * The Mach Operating System project at Carnegie-Mellon University.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	from: @(#)vm_page.h	8.2 (Berkeley) 12/13/93
33  *
34  *
35  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36  * All rights reserved.
37  *
38  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
39  *
40  * Permission to use, copy, modify and distribute this software and
41  * its documentation is hereby granted, provided that both the copyright
42  * notice and this permission notice appear in all copies of the
43  * software, derivative works or modified versions, and any portions
44  * thereof, and that both notices appear in supporting documentation.
45  *
46  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
49  *
50  * Carnegie Mellon requests users of this software to return to
51  *
52  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
53  *  School of Computer Science
54  *  Carnegie Mellon University
55  *  Pittsburgh PA 15213-3890
56  *
57  * any improvements or extensions that they make and grant Carnegie the
58  * rights to redistribute these changes.
59  *
60  * $FreeBSD$
61  */
62 
63 /*
64  *	Resident memory system definitions.
65  */
66 
67 #ifndef	_VM_PAGE_
68 #define	_VM_PAGE_
69 
70 #include <vm/pmap.h>
71 
72 /*
73  *	Management of resident (logical) pages.
74  *
75  *	A small structure is kept for each resident
76  *	page, indexed by page number.  Each structure
77  *	is an element of several lists:
78  *
79  *		A hash table bucket used to quickly
80  *		perform object/offset lookups
81  *
82  *		A list of all pages for a given object,
83  *		so they can be quickly deactivated at
84  *		time of deallocation.
85  *
86  *		An ordered list of pages due for pageout.
87  *
88  *	In addition, the structure contains the object
89  *	and offset to which this page belongs (for pageout),
90  *	and sundry status bits.
91  *
92  *	In general, operations on this structure's mutable fields are
93  *	synchronized using either one of or a combination of the lock on the
94  *	object that the page belongs to (O), the pool lock for the page (P),
95  *	or the lock for either the free or paging queue (Q).  If a field is
96  *	annotated below with two of these locks, then holding either lock is
97  *	sufficient for read access, but both locks are required for write
98  *	access.
99  *
100  *	In contrast, the synchronization of accesses to the page's
101  *	dirty field is machine dependent (M).  In the
102  *	machine-independent layer, the lock on the object that the
103  *	page belongs to must be held in order to operate on the field.
104  *	However, the pmap layer is permitted to set all bits within
105  *	the field without holding that lock.  If the underlying
106  *	architecture does not support atomic read-modify-write
107  *	operations on the field's type, then the machine-independent
108  *	layer uses a 32-bit atomic on the aligned 32-bit word that
109  *	contains the dirty field.  In the machine-independent layer,
110  *	the implementation of read-modify-write operations on the
111  *	field is encapsulated in vm_page_clear_dirty_mask().
112  */
113 
114 #if PAGE_SIZE == 4096
115 #define VM_PAGE_BITS_ALL 0xffu
116 typedef uint8_t vm_page_bits_t;
117 #elif PAGE_SIZE == 8192
118 #define VM_PAGE_BITS_ALL 0xffffu
119 typedef uint16_t vm_page_bits_t;
120 #elif PAGE_SIZE == 16384
121 #define VM_PAGE_BITS_ALL 0xffffffffu
122 typedef uint32_t vm_page_bits_t;
123 #elif PAGE_SIZE == 32768
124 #define VM_PAGE_BITS_ALL 0xfffffffffffffffflu
125 typedef uint64_t vm_page_bits_t;
126 #endif
127 
128 struct vm_page {
129 	TAILQ_ENTRY(vm_page) pageq;	/* page queue or free list (Q)	*/
130 	TAILQ_ENTRY(vm_page) listq;	/* pages in same object (O) 	*/
131 	struct vm_page *left;		/* splay tree link (O)		*/
132 	struct vm_page *right;		/* splay tree link (O)		*/
133 
134 	vm_object_t object;		/* which object am I in (O,P)*/
135 	vm_pindex_t pindex;		/* offset into object (O,P) */
136 	vm_paddr_t phys_addr;		/* physical address of page */
137 	struct md_page md;		/* machine dependant stuff */
138 	uint8_t	queue;			/* page queue index (P,Q) */
139 	int8_t segind;
140 	short hold_count;		/* page hold count (P) */
141 	uint8_t	order;			/* index of the buddy queue */
142 	uint8_t pool;
143 	u_short cow;			/* page cow mapping count (P) */
144 	u_int wire_count;		/* wired down maps refs (P) */
145 	uint8_t aflags;			/* access is atomic */
146 	uint8_t oflags;			/* page VPO_* flags (O) */
147 	uint16_t flags;			/* page PG_* flags (P) */
148 	u_char	act_count;		/* page usage count (O) */
149 	u_char	busy;			/* page busy count (O) */
150 	/* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
151 	/* so, on normal X86 kernels, they must be at least 8 bits wide */
152 	vm_page_bits_t valid;		/* map of valid DEV_BSIZE chunks (O) */
153 	vm_page_bits_t dirty;		/* map of dirty DEV_BSIZE chunks (M) */
154 };
155 
156 /*
157  * Page flags stored in oflags:
158  *
159  * Access to these page flags is synchronized by the lock on the object
160  * containing the page (O).
161  *
162  * Note: VPO_UNMANAGED (used by OBJT_DEVICE, OBJT_PHYS and OBJT_SG)
163  * 	 indicates that the page is not under PV management but
164  * 	 otherwise should be treated as a normal page.  Pages not
165  * 	 under PV management cannot be paged out via the
166  * 	 object/vm_page_t because there is no knowledge of their pte
167  * 	 mappings, and such pages are also not on any PQ queue.
168  *
169  */
170 #define	VPO_BUSY	0x01		/* page is in transit */
171 #define	VPO_WANTED	0x02		/* someone is waiting for page */
172 #define	VPO_UNMANAGED	0x04		/* no PV management for page */
173 #define	VPO_SWAPINPROG	0x08		/* swap I/O in progress on page */
174 #define	VPO_NOSYNC	0x10		/* do not collect for syncer */
175 
176 #define	PQ_NONE		255
177 #define	PQ_INACTIVE	0
178 #define	PQ_ACTIVE	1
179 #define	PQ_COUNT	2
180 
181 TAILQ_HEAD(pglist, vm_page);
182 
183 struct vm_pagequeue {
184 	struct mtx	pq_mutex;
185 	struct pglist	pq_pl;
186 	int *const	pq_cnt;
187 	const char *const pq_name;
188 } __aligned(CACHE_LINE_SIZE);
189 
190 extern struct vm_pagequeue vm_pagequeues[PQ_COUNT];
191 
192 #define	vm_pagequeue_assert_locked(pq)	mtx_assert(&(pq)->pq_mutex, MA_OWNED)
193 #define	vm_pagequeue_init_lock(pq)	mtx_init(&(pq)->pq_mutex,	\
194 	    (pq)->pq_name, "vm pagequeue", MTX_DEF | MTX_DUPOK);
195 #define	vm_pagequeue_lock(pq)		mtx_lock(&(pq)->pq_mutex)
196 #define	vm_pagequeue_unlock(pq)		mtx_unlock(&(pq)->pq_mutex)
197 
198 extern struct mtx_padalign vm_page_queue_free_mtx;
199 extern struct mtx_padalign pa_lock[];
200 
201 #if defined(__arm__)
202 #define	PDRSHIFT	PDR_SHIFT
203 #elif !defined(PDRSHIFT)
204 #define PDRSHIFT	21
205 #endif
206 
207 #define	pa_index(pa)	((pa) >> PDRSHIFT)
208 #define	PA_LOCKPTR(pa)	((struct mtx *)(&pa_lock[pa_index(pa) % PA_LOCK_COUNT]))
209 #define	PA_LOCKOBJPTR(pa)	((struct lock_object *)PA_LOCKPTR((pa)))
210 #define	PA_LOCK(pa)	mtx_lock(PA_LOCKPTR(pa))
211 #define	PA_TRYLOCK(pa)	mtx_trylock(PA_LOCKPTR(pa))
212 #define	PA_UNLOCK(pa)	mtx_unlock(PA_LOCKPTR(pa))
213 #define	PA_UNLOCK_COND(pa) 			\
214 	do {		   			\
215 		if ((pa) != 0) {		\
216 			PA_UNLOCK((pa));	\
217 			(pa) = 0;		\
218 		}				\
219 	} while (0)
220 
221 #define	PA_LOCK_ASSERT(pa, a)	mtx_assert(PA_LOCKPTR(pa), (a))
222 
223 #ifdef KLD_MODULE
224 #define	vm_page_lock(m)		vm_page_lock_KBI((m), LOCK_FILE, LOCK_LINE)
225 #define	vm_page_unlock(m)	vm_page_unlock_KBI((m), LOCK_FILE, LOCK_LINE)
226 #define	vm_page_trylock(m)	vm_page_trylock_KBI((m), LOCK_FILE, LOCK_LINE)
227 #if defined(INVARIANTS)
228 #define	vm_page_lock_assert(m, a)		\
229     vm_page_lock_assert_KBI((m), (a), __FILE__, __LINE__)
230 #else
231 #define	vm_page_lock_assert(m, a)
232 #endif
233 #else	/* !KLD_MODULE */
234 #define	vm_page_lockptr(m)	(PA_LOCKPTR(VM_PAGE_TO_PHYS((m))))
235 #define	vm_page_lock(m)		mtx_lock(vm_page_lockptr((m)))
236 #define	vm_page_unlock(m)	mtx_unlock(vm_page_lockptr((m)))
237 #define	vm_page_trylock(m)	mtx_trylock(vm_page_lockptr((m)))
238 #define	vm_page_lock_assert(m, a)	mtx_assert(vm_page_lockptr((m)), (a))
239 #endif
240 
241 /*
242  * The vm_page's aflags are updated using atomic operations.  To set or clear
243  * these flags, the functions vm_page_aflag_set() and vm_page_aflag_clear()
244  * must be used.  Neither these flags nor these functions are part of the KBI.
245  *
246  * PGA_REFERENCED may be cleared only if the object containing the page is
247  * locked.  It is set by both the MI and MD VM layers.  However, kernel
248  * loadable modules should not directly set this flag.  They should call
249  * vm_page_reference() instead.
250  *
251  * PGA_WRITEABLE is set exclusively on managed pages by pmap_enter().  When it
252  * does so, the page must be VPO_BUSY.  The MI VM layer must never access this
253  * flag directly.  Instead, it should call pmap_page_is_write_mapped().
254  *
255  * PGA_EXECUTABLE may be set by pmap routines, and indicates that a page has
256  * at least one executable mapping.  It is not consumed by the MI VM layer.
257  */
258 #define	PGA_WRITEABLE	0x01		/* page may be mapped writeable */
259 #define	PGA_REFERENCED	0x02		/* page has been referenced */
260 #define	PGA_EXECUTABLE	0x04		/* page may be mapped executable */
261 
262 /*
263  * Page flags.  If changed at any other time than page allocation or
264  * freeing, the modification must be protected by the vm_page lock.
265  */
266 #define	PG_CACHED	0x0001		/* page is cached */
267 #define	PG_FREE		0x0002		/* page is free */
268 #define	PG_FICTITIOUS	0x0004		/* physical page doesn't exist */
269 #define	PG_ZERO		0x0008		/* page is zeroed */
270 #define	PG_MARKER	0x0010		/* special queue marker page */
271 #define	PG_SLAB		0x0020		/* object pointer is actually a slab */
272 #define	PG_WINATCFLS	0x0040		/* flush dirty page on inactive q */
273 #define	PG_NODUMP	0x0080		/* don't include this page in a dump */
274 #define	PG_UNHOLDFREE	0x0100		/* delayed free of a held page */
275 
276 /*
277  * Misc constants.
278  */
279 #define ACT_DECLINE		1
280 #define ACT_ADVANCE		3
281 #define ACT_INIT		5
282 #define ACT_MAX			64
283 
284 #ifdef _KERNEL
285 
286 #include <sys/systm.h>
287 
288 #include <machine/atomic.h>
289 
290 /*
291  * Each pageable resident page falls into one of five lists:
292  *
293  *	free
294  *		Available for allocation now.
295  *
296  *	cache
297  *		Almost available for allocation. Still associated with
298  *		an object, but clean and immediately freeable.
299  *
300  *	hold
301  *		Will become free after a pending I/O operation
302  *		completes.
303  *
304  * The following lists are LRU sorted:
305  *
306  *	inactive
307  *		Low activity, candidates for reclamation.
308  *		This is the list of pages that should be
309  *		paged out next.
310  *
311  *	active
312  *		Pages that are "active" i.e. they have been
313  *		recently referenced.
314  *
315  */
316 
317 extern int vm_page_zero_count;
318 
319 extern vm_page_t vm_page_array;		/* First resident page in table */
320 extern long vm_page_array_size;		/* number of vm_page_t's */
321 extern long first_page;			/* first physical page number */
322 
323 #define	VM_PAGE_IS_FREE(m)	(((m)->flags & PG_FREE) != 0)
324 
325 #define VM_PAGE_TO_PHYS(entry)	((entry)->phys_addr)
326 
327 vm_page_t vm_phys_paddr_to_vm_page(vm_paddr_t pa);
328 
329 vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa);
330 
331 /* page allocation classes: */
332 #define VM_ALLOC_NORMAL		0
333 #define VM_ALLOC_INTERRUPT	1
334 #define VM_ALLOC_SYSTEM		2
335 #define	VM_ALLOC_CLASS_MASK	3
336 /* page allocation flags: */
337 #define	VM_ALLOC_WIRED		0x0020	/* non pageable */
338 #define	VM_ALLOC_ZERO		0x0040	/* Try to obtain a zeroed page */
339 #define	VM_ALLOC_RETRY		0x0080	/* Mandatory with vm_page_grab() */
340 #define	VM_ALLOC_NOOBJ		0x0100	/* No associated object */
341 #define	VM_ALLOC_NOBUSY		0x0200	/* Do not busy the page */
342 #define	VM_ALLOC_IFCACHED	0x0400	/* Fail if the page is not cached */
343 #define	VM_ALLOC_IFNOTCACHED	0x0800	/* Fail if the page is cached */
344 #define	VM_ALLOC_IGN_SBUSY	0x1000	/* vm_page_grab() only */
345 #define	VM_ALLOC_NODUMP		0x2000	/* don't include in dump */
346 
347 #define	VM_ALLOC_COUNT_SHIFT	16
348 #define	VM_ALLOC_COUNT(count)	((count) << VM_ALLOC_COUNT_SHIFT)
349 
350 #ifdef M_NOWAIT
351 static inline int
352 malloc2vm_flags(int malloc_flags)
353 {
354 	int pflags;
355 
356 	pflags = (malloc_flags & M_USE_RESERVE) != 0 ? VM_ALLOC_INTERRUPT :
357 	    VM_ALLOC_SYSTEM;
358 	if ((malloc_flags & M_ZERO) != 0)
359 		pflags |= VM_ALLOC_ZERO;
360 	if ((malloc_flags & M_NODUMP) != 0)
361 		pflags |= VM_ALLOC_NODUMP;
362 	return (pflags);
363 }
364 #endif
365 
366 void vm_page_busy(vm_page_t m);
367 void vm_page_flash(vm_page_t m);
368 void vm_page_io_start(vm_page_t m);
369 void vm_page_io_finish(vm_page_t m);
370 void vm_page_hold(vm_page_t mem);
371 void vm_page_unhold(vm_page_t mem);
372 void vm_page_free(vm_page_t m);
373 void vm_page_free_zero(vm_page_t m);
374 void vm_page_wakeup(vm_page_t m);
375 
376 void vm_page_activate (vm_page_t);
377 vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
378 vm_page_t vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
379     u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
380     vm_paddr_t boundary, vm_memattr_t memattr);
381 vm_page_t vm_page_alloc_freelist(int, int);
382 vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
383 void vm_page_cache(vm_page_t);
384 void vm_page_cache_free(vm_object_t, vm_pindex_t, vm_pindex_t);
385 void vm_page_cache_transfer(vm_object_t, vm_pindex_t, vm_object_t);
386 int vm_page_try_to_cache (vm_page_t);
387 int vm_page_try_to_free (vm_page_t);
388 void vm_page_dontneed(vm_page_t);
389 void vm_page_deactivate (vm_page_t);
390 void vm_page_dequeue(vm_page_t m);
391 void vm_page_dequeue_locked(vm_page_t m);
392 vm_page_t vm_page_find_least(vm_object_t, vm_pindex_t);
393 vm_page_t vm_page_getfake(vm_paddr_t paddr, vm_memattr_t memattr);
394 void vm_page_initfake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr);
395 void vm_page_insert (vm_page_t, vm_object_t, vm_pindex_t);
396 boolean_t vm_page_is_cached(vm_object_t object, vm_pindex_t pindex);
397 vm_page_t vm_page_lookup (vm_object_t, vm_pindex_t);
398 vm_page_t vm_page_next(vm_page_t m);
399 int vm_page_pa_tryrelock(pmap_t, vm_paddr_t, vm_paddr_t *);
400 vm_page_t vm_page_prev(vm_page_t m);
401 void vm_page_putfake(vm_page_t m);
402 void vm_page_readahead_finish(vm_page_t m);
403 void vm_page_reference(vm_page_t m);
404 void vm_page_remove (vm_page_t);
405 void vm_page_rename (vm_page_t, vm_object_t, vm_pindex_t);
406 void vm_page_requeue(vm_page_t m);
407 void vm_page_requeue_locked(vm_page_t m);
408 void vm_page_set_valid_range(vm_page_t m, int base, int size);
409 void vm_page_sleep(vm_page_t m, const char *msg);
410 vm_page_t vm_page_splay(vm_pindex_t, vm_page_t);
411 vm_offset_t vm_page_startup(vm_offset_t vaddr);
412 void vm_page_unhold_pages(vm_page_t *ma, int count);
413 void vm_page_unwire (vm_page_t, int);
414 void vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr);
415 void vm_page_wire (vm_page_t);
416 void vm_page_set_validclean (vm_page_t, int, int);
417 void vm_page_clear_dirty (vm_page_t, int, int);
418 void vm_page_set_invalid (vm_page_t, int, int);
419 int vm_page_is_valid (vm_page_t, int, int);
420 void vm_page_test_dirty (vm_page_t);
421 vm_page_bits_t vm_page_bits(int base, int size);
422 void vm_page_zero_invalid(vm_page_t m, boolean_t setvalid);
423 void vm_page_free_toq(vm_page_t m);
424 void vm_page_zero_idle_wakeup(void);
425 void vm_page_cowfault (vm_page_t);
426 int vm_page_cowsetup(vm_page_t);
427 void vm_page_cowclear (vm_page_t);
428 
429 void vm_page_dirty_KBI(vm_page_t m);
430 void vm_page_lock_KBI(vm_page_t m, const char *file, int line);
431 void vm_page_unlock_KBI(vm_page_t m, const char *file, int line);
432 int vm_page_trylock_KBI(vm_page_t m, const char *file, int line);
433 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
434 void vm_page_lock_assert_KBI(vm_page_t m, int a, const char *file, int line);
435 #endif
436 
437 #ifdef INVARIANTS
438 void vm_page_object_lock_assert(vm_page_t m);
439 #define	VM_PAGE_OBJECT_LOCK_ASSERT(m)	vm_page_object_lock_assert(m)
440 #else
441 #define	VM_PAGE_OBJECT_LOCK_ASSERT(m)	(void)0
442 #endif
443 
444 /*
445  * We want to use atomic updates for the aflags field, which is 8 bits wide.
446  * However, not all architectures support atomic operations on 8-bit
447  * destinations.  In order that we can easily use a 32-bit operation, we
448  * require that the aflags field be 32-bit aligned.
449  */
450 CTASSERT(offsetof(struct vm_page, aflags) % sizeof(uint32_t) == 0);
451 
452 /*
453  *	Clear the given bits in the specified page.
454  */
455 static inline void
456 vm_page_aflag_clear(vm_page_t m, uint8_t bits)
457 {
458 	uint32_t *addr, val;
459 
460 	/*
461 	 * The PGA_REFERENCED flag can only be cleared if the object
462 	 * containing the page is locked.
463 	 */
464 	if ((bits & PGA_REFERENCED) != 0)
465 		VM_PAGE_OBJECT_LOCK_ASSERT(m);
466 
467 	/*
468 	 * Access the whole 32-bit word containing the aflags field with an
469 	 * atomic update.  Parallel non-atomic updates to the other fields
470 	 * within this word are handled properly by the atomic update.
471 	 */
472 	addr = (void *)&m->aflags;
473 	KASSERT(((uintptr_t)addr & (sizeof(uint32_t) - 1)) == 0,
474 	    ("vm_page_aflag_clear: aflags is misaligned"));
475 	val = bits;
476 #if BYTE_ORDER == BIG_ENDIAN
477 	val <<= 24;
478 #endif
479 	atomic_clear_32(addr, val);
480 }
481 
482 /*
483  *	Set the given bits in the specified page.
484  */
485 static inline void
486 vm_page_aflag_set(vm_page_t m, uint8_t bits)
487 {
488 	uint32_t *addr, val;
489 
490 	/*
491 	 * The PGA_WRITEABLE flag can only be set if the page is managed and
492 	 * VPO_BUSY.  Currently, this flag is only set by pmap_enter().
493 	 */
494 	KASSERT((bits & PGA_WRITEABLE) == 0 ||
495 	    (m->oflags & (VPO_UNMANAGED | VPO_BUSY)) == VPO_BUSY,
496 	    ("vm_page_aflag_set: PGA_WRITEABLE and !VPO_BUSY"));
497 
498 	/*
499 	 * Access the whole 32-bit word containing the aflags field with an
500 	 * atomic update.  Parallel non-atomic updates to the other fields
501 	 * within this word are handled properly by the atomic update.
502 	 */
503 	addr = (void *)&m->aflags;
504 	KASSERT(((uintptr_t)addr & (sizeof(uint32_t) - 1)) == 0,
505 	    ("vm_page_aflag_set: aflags is misaligned"));
506 	val = bits;
507 #if BYTE_ORDER == BIG_ENDIAN
508 	val <<= 24;
509 #endif
510 	atomic_set_32(addr, val);
511 }
512 
513 /*
514  *	vm_page_dirty:
515  *
516  *	Set all bits in the page's dirty field.
517  *
518  *	The object containing the specified page must be locked if the
519  *	call is made from the machine-independent layer.
520  *
521  *	See vm_page_clear_dirty_mask().
522  */
523 static __inline void
524 vm_page_dirty(vm_page_t m)
525 {
526 
527 	/* Use vm_page_dirty_KBI() under INVARIANTS to save memory. */
528 #if defined(KLD_MODULE) || defined(INVARIANTS)
529 	vm_page_dirty_KBI(m);
530 #else
531 	m->dirty = VM_PAGE_BITS_ALL;
532 #endif
533 }
534 
535 /*
536  *	vm_page_remque:
537  *
538  *	If the given page is in a page queue, then remove it from that page
539  *	queue.
540  *
541  *	The page must be locked.
542  */
543 static inline void
544 vm_page_remque(vm_page_t m)
545 {
546 
547 	if (m->queue != PQ_NONE)
548 		vm_page_dequeue(m);
549 }
550 
551 /*
552  *	vm_page_sleep_if_busy:
553  *
554  *	Sleep and release the page queues lock if VPO_BUSY is set or,
555  *	if also_m_busy is TRUE, busy is non-zero.  Returns TRUE if the
556  *	thread slept and the page queues lock was released.
557  *	Otherwise, retains the page queues lock and returns FALSE.
558  *
559  *	The object containing the given page must be locked.
560  */
561 static __inline int
562 vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg)
563 {
564 
565 	if ((m->oflags & VPO_BUSY) || (also_m_busy && m->busy)) {
566 		vm_page_sleep(m, msg);
567 		return (TRUE);
568 	}
569 	return (FALSE);
570 }
571 
572 /*
573  *	vm_page_undirty:
574  *
575  *	Set page to not be dirty.  Note: does not clear pmap modify bits
576  */
577 static __inline void
578 vm_page_undirty(vm_page_t m)
579 {
580 
581 	VM_PAGE_OBJECT_LOCK_ASSERT(m);
582 	m->dirty = 0;
583 }
584 
585 #endif				/* _KERNEL */
586 #endif				/* !_VM_PAGE_ */
587