1 /* $OpenBSD: uvm_anon.c,v 1.21 2002/03/14 01:27:18 millert Exp $ */
2 /* $NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 chs Exp $ */
3
4 /*
5 *
6 * Copyright (c) 1997 Charles D. Cranor and Washington University.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by Charles D. Cranor and
20 * Washington University.
21 * 4. The name of the author may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 /*
37 * uvm_anon.c: uvm anon ops
38 */
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/proc.h>
43 #include <sys/malloc.h>
44 #include <sys/pool.h>
45 #include <sys/kernel.h>
46
47 #include <uvm/uvm.h>
48 #include <uvm/uvm_swap.h>
49
50 /*
51 * anonblock_list: global list of anon blocks,
52 * locked by swap_syscall_lock (since we never remove
53 * anything from this list and we only add to it via swapctl(2)).
54 */
55
56 struct uvm_anonblock {
57 LIST_ENTRY(uvm_anonblock) list;
58 int count;
59 struct vm_anon *anons;
60 };
61 static LIST_HEAD(anonlist, uvm_anonblock) anonblock_list;
62
63
64 static boolean_t anon_pagein(struct vm_anon *);
65
66
67 /*
68 * allocate anons
69 */
70 void
uvm_anon_init()71 uvm_anon_init()
72 {
73 int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */
74
75 simple_lock_init(&uvm.afreelock);
76 LIST_INIT(&anonblock_list);
77
78 /*
79 * Allocate the initial anons.
80 */
81 uvm_anon_add(nanon);
82 }
83
84 /*
85 * add some more anons to the free pool. called when we add
86 * more swap space.
87 *
88 * => swap_syscall_lock should be held (protects anonblock_list).
89 */
90 int
uvm_anon_add(count)91 uvm_anon_add(count)
92 int count;
93 {
94 struct uvm_anonblock *anonblock;
95 struct vm_anon *anon;
96 int lcv, needed;
97
98 simple_lock(&uvm.afreelock);
99 uvmexp.nanonneeded += count;
100 needed = uvmexp.nanonneeded - uvmexp.nanon;
101 simple_unlock(&uvm.afreelock);
102
103 if (needed <= 0) {
104 return 0;
105 }
106
107 anon = (void *)uvm_km_alloc(kernel_map, sizeof(*anon) * needed);
108
109 /* XXX Should wait for VM to free up. */
110 if (anon == NULL) {
111 printf("uvm_anon_add: can not allocate %d anons\n", needed);
112 panic("uvm_anon_add");
113 }
114
115 MALLOC(anonblock, void *, sizeof(*anonblock), M_UVMAMAP, M_WAITOK);
116
117 anonblock->count = needed;
118 anonblock->anons = anon;
119 LIST_INSERT_HEAD(&anonblock_list, anonblock, list);
120 memset(anon, 0, sizeof(*anon) * needed);
121
122 simple_lock(&uvm.afreelock);
123 uvmexp.nanon += needed;
124 uvmexp.nfreeanon += needed;
125 for (lcv = 0; lcv < needed; lcv++) {
126 simple_lock_init(&anon->an_lock);
127 anon[lcv].u.an_nxt = uvm.afree;
128 uvm.afree = &anon[lcv];
129 simple_lock_init(&uvm.afree->an_lock);
130 }
131 simple_unlock(&uvm.afreelock);
132 return 0;
133 }
134
135 /*
136 * remove anons from the free pool.
137 */
138 void
uvm_anon_remove(count)139 uvm_anon_remove(count)
140 int count;
141 {
142 /*
143 * we never actually free any anons, to avoid allocation overhead.
144 * XXX someday we might want to try to free anons.
145 */
146
147 simple_lock(&uvm.afreelock);
148 uvmexp.nanonneeded -= count;
149 simple_unlock(&uvm.afreelock);
150 }
151
152 /*
153 * allocate an anon
154 */
155 struct vm_anon *
uvm_analloc()156 uvm_analloc()
157 {
158 struct vm_anon *a;
159
160 simple_lock(&uvm.afreelock);
161 a = uvm.afree;
162 if (a) {
163 uvm.afree = a->u.an_nxt;
164 uvmexp.nfreeanon--;
165 a->an_ref = 1;
166 a->an_swslot = 0;
167 a->u.an_page = NULL; /* so we can free quickly */
168 }
169 simple_unlock(&uvm.afreelock);
170 return(a);
171 }
172
173 /*
174 * uvm_anfree: free a single anon structure
175 *
176 * => caller must remove anon from its amap before calling (if it was in
177 * an amap).
178 * => anon must be unlocked and have a zero reference count.
179 * => we may lock the pageq's.
180 */
181 void
uvm_anfree(anon)182 uvm_anfree(anon)
183 struct vm_anon *anon;
184 {
185 struct vm_page *pg;
186 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist);
187 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0);
188
189 /*
190 * get page
191 */
192
193 pg = anon->u.an_page;
194
195 /*
196 * if there is a resident page and it is loaned, then anon may not
197 * own it. call out to uvm_anon_lockpage() to ensure the real owner
198 * of the page has been identified and locked.
199 */
200
201 if (pg && pg->loan_count)
202 pg = uvm_anon_lockloanpg(anon);
203
204 /*
205 * if we have a resident page, we must dispose of it before freeing
206 * the anon.
207 */
208
209 if (pg) {
210
211 /*
212 * if the page is owned by a uobject (now locked), then we must
213 * kill the loan on the page rather than free it.
214 */
215
216 if (pg->uobject) {
217 uvm_lock_pageq();
218 KASSERT(pg->loan_count > 0);
219 pg->loan_count--;
220 pg->uanon = NULL;
221 uvm_unlock_pageq();
222 simple_unlock(&pg->uobject->vmobjlock);
223 } else {
224
225 /*
226 * page has no uobject, so we must be the owner of it.
227 *
228 * if page is busy then we just mark it as released
229 * (who ever has it busy must check for this when they
230 * wake up). if the page is not busy then we can
231 * free it now.
232 */
233
234 if ((pg->flags & PG_BUSY) != 0) {
235 /* tell them to dump it when done */
236 pg->flags |= PG_RELEASED;
237 UVMHIST_LOG(maphist,
238 " anon 0x%x, page 0x%x: BUSY (released!)",
239 anon, pg, 0, 0);
240 return;
241 }
242 pmap_page_protect(pg, VM_PROT_NONE);
243 uvm_lock_pageq(); /* lock out pagedaemon */
244 uvm_pagefree(pg); /* bye bye */
245 uvm_unlock_pageq(); /* free the daemon */
246 UVMHIST_LOG(maphist,"anon 0x%x, page 0x%x: freed now!",
247 anon, pg, 0, 0);
248 }
249 }
250
251 /*
252 * free any swap resources.
253 */
254 uvm_anon_dropswap(anon);
255
256 /*
257 * now that we've stripped the data areas from the anon, free the anon
258 * itself!
259 */
260 simple_lock(&uvm.afreelock);
261 anon->u.an_nxt = uvm.afree;
262 uvm.afree = anon;
263 uvmexp.nfreeanon++;
264 simple_unlock(&uvm.afreelock);
265 UVMHIST_LOG(maphist,"<- done!",0,0,0,0);
266 }
267
268 /*
269 * uvm_anon_dropswap: release any swap resources from this anon.
270 *
271 * => anon must be locked or have a reference count of 0.
272 */
273 void
uvm_anon_dropswap(anon)274 uvm_anon_dropswap(anon)
275 struct vm_anon *anon;
276 {
277 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist);
278
279 if (anon->an_swslot == 0)
280 return;
281
282 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x",
283 anon, anon->an_swslot, 0, 0);
284 uvm_swap_free(anon->an_swslot, 1);
285 anon->an_swslot = 0;
286
287 if (anon->u.an_page == NULL) {
288 /* this page is no longer only in swap. */
289 simple_lock(&uvm.swap_data_lock);
290 uvmexp.swpgonly--;
291 simple_unlock(&uvm.swap_data_lock);
292 }
293 }
294
295 /*
296 * uvm_anon_lockloanpg: given a locked anon, lock its resident page
297 *
298 * => anon is locked by caller
299 * => on return: anon is locked
300 * if there is a resident page:
301 * if it has a uobject, it is locked by us
302 * if it is ownerless, we take over as owner
303 * we return the resident page (it can change during
304 * this function)
305 * => note that the only time an anon has an ownerless resident page
306 * is if the page was loaned from a uvm_object and the uvm_object
307 * disowned it
308 * => this only needs to be called when you want to do an operation
309 * on an anon's resident page and that page has a non-zero loan
310 * count.
311 */
312 struct vm_page *
uvm_anon_lockloanpg(anon)313 uvm_anon_lockloanpg(anon)
314 struct vm_anon *anon;
315 {
316 struct vm_page *pg;
317 boolean_t locked = FALSE;
318
319 /*
320 * loop while we have a resident page that has a non-zero loan count.
321 * if we successfully get our lock, we will "break" the loop.
322 * note that the test for pg->loan_count is not protected -- this
323 * may produce false positive results. note that a false positive
324 * result may cause us to do more work than we need to, but it will
325 * not produce an incorrect result.
326 */
327
328 while (((pg = anon->u.an_page) != NULL) && pg->loan_count != 0) {
329
330 /*
331 * quickly check to see if the page has an object before
332 * bothering to lock the page queues. this may also produce
333 * a false positive result, but that's ok because we do a real
334 * check after that.
335 *
336 * XXX: quick check -- worth it? need volatile?
337 */
338
339 if (pg->uobject) {
340
341 uvm_lock_pageq();
342 if (pg->uobject) { /* the "real" check */
343 locked =
344 simple_lock_try(&pg->uobject->vmobjlock);
345 } else {
346 /* object disowned before we got PQ lock */
347 locked = TRUE;
348 }
349 uvm_unlock_pageq();
350
351 /*
352 * if we didn't get a lock (try lock failed), then we
353 * toggle our anon lock and try again
354 */
355
356 if (!locked) {
357 simple_unlock(&anon->an_lock);
358
359 /*
360 * someone locking the object has a chance to
361 * lock us right now
362 */
363
364 simple_lock(&anon->an_lock);
365 continue;
366 }
367 }
368
369 /*
370 * if page is un-owned [i.e. the object dropped its ownership],
371 * then we can take over as owner!
372 */
373
374 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) {
375 uvm_lock_pageq();
376 pg->pqflags |= PQ_ANON; /* take ownership... */
377 pg->loan_count--; /* ... and drop our loan */
378 uvm_unlock_pageq();
379 }
380
381 /*
382 * we did it! break the loop
383 */
384
385 break;
386 }
387 return(pg);
388 }
389
390
391
392 /*
393 * page in every anon that is paged out to a range of swslots.
394 *
395 * swap_syscall_lock should be held (protects anonblock_list).
396 */
397
398 boolean_t
anon_swap_off(startslot,endslot)399 anon_swap_off(startslot, endslot)
400 int startslot, endslot;
401 {
402 struct uvm_anonblock *anonblock;
403
404 for (anonblock = LIST_FIRST(&anonblock_list);
405 anonblock != NULL;
406 anonblock = LIST_NEXT(anonblock, list)) {
407 int i;
408
409 /*
410 * loop thru all the anons in the anonblock,
411 * paging in where needed.
412 */
413
414 for (i = 0; i < anonblock->count; i++) {
415 struct vm_anon *anon = &anonblock->anons[i];
416 int slot;
417
418 /*
419 * lock anon to work on it.
420 */
421
422 simple_lock(&anon->an_lock);
423
424 /*
425 * is this anon's swap slot in range?
426 */
427
428 slot = anon->an_swslot;
429 if (slot >= startslot && slot < endslot) {
430 boolean_t rv;
431
432 /*
433 * yup, page it in.
434 */
435
436 /* locked: anon */
437 rv = anon_pagein(anon);
438 /* unlocked: anon */
439
440 if (rv) {
441 return rv;
442 }
443 } else {
444
445 /*
446 * nope, unlock and proceed.
447 */
448
449 simple_unlock(&anon->an_lock);
450 }
451 }
452 }
453 return FALSE;
454 }
455
456
457 /*
458 * fetch an anon's page.
459 *
460 * => anon must be locked, and is unlocked upon return.
461 * => returns TRUE if pagein was aborted due to lack of memory.
462 */
463
464 static boolean_t
anon_pagein(anon)465 anon_pagein(anon)
466 struct vm_anon *anon;
467 {
468 struct vm_page *pg;
469 struct uvm_object *uobj;
470 int rv;
471
472 /* locked: anon */
473 rv = uvmfault_anonget(NULL, NULL, anon);
474 /*
475 * if rv == VM_PAGER_OK, anon is still locked, else anon
476 * is unlocked
477 */
478
479 switch (rv) {
480 case VM_PAGER_OK:
481 break;
482
483 case VM_PAGER_ERROR:
484 case VM_PAGER_REFAULT:
485
486 /*
487 * nothing more to do on errors.
488 * VM_PAGER_REFAULT can only mean that the anon was freed,
489 * so again there's nothing to do.
490 */
491
492 return FALSE;
493
494 default:
495 #ifdef DIAGNOSTIC
496 panic("anon_pagein: uvmfault_anonget -> %d", rv);
497 #else
498 return FALSE;
499 #endif
500 }
501
502 /*
503 * ok, we've got the page now.
504 * mark it as dirty, clear its swslot and un-busy it.
505 */
506
507 pg = anon->u.an_page;
508 uobj = pg->uobject;
509 uvm_swap_free(anon->an_swslot, 1);
510 anon->an_swslot = 0;
511 pg->flags &= ~(PG_CLEAN);
512
513 /*
514 * deactivate the page (to put it on a page queue)
515 */
516
517 pmap_clear_reference(pg);
518 #ifndef UBC
519 pmap_page_protect(pg, VM_PROT_NONE);
520 #endif
521 uvm_lock_pageq();
522 uvm_pagedeactivate(pg);
523 uvm_unlock_pageq();
524
525 /*
526 * unlock the anon and we're done.
527 */
528
529 simple_unlock(&anon->an_lock);
530 if (uobj) {
531 simple_unlock(&uobj->vmobjlock);
532 }
533 return FALSE;
534 }
535