1 /* $NetBSD: uvm_anon.c,v 1.27 2004/01/06 15:56:49 chs Exp $ */ 2 3 /* 4 * 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * All rights reserved. 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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Charles D. Cranor and 19 * Washington University. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /* 36 * uvm_anon.c: uvm anon ops 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.27 2004/01/06 15:56:49 chs Exp $"); 41 42 #include "opt_uvmhist.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/proc.h> 47 #include <sys/malloc.h> 48 #include <sys/pool.h> 49 #include <sys/kernel.h> 50 51 #include <uvm/uvm.h> 52 #include <uvm/uvm_swap.h> 53 54 /* 55 * anonblock_list: global list of anon blocks, 56 * locked by swap_syscall_lock (since we never remove 57 * anything from this list and we only add to it via swapctl(2)). 58 */ 59 60 struct uvm_anonblock { 61 LIST_ENTRY(uvm_anonblock) list; 62 int count; 63 struct vm_anon *anons; 64 }; 65 static LIST_HEAD(anonlist, uvm_anonblock) anonblock_list; 66 67 68 static boolean_t anon_pagein __P((struct vm_anon *)); 69 70 71 /* 72 * allocate anons 73 */ 74 void 75 uvm_anon_init() 76 { 77 int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */ 78 79 simple_lock_init(&uvm.afreelock); 80 LIST_INIT(&anonblock_list); 81 82 /* 83 * Allocate the initial anons. 84 */ 85 uvm_anon_add(nanon); 86 } 87 88 /* 89 * add some more anons to the free pool. called when we add 90 * more swap space. 91 * 92 * => swap_syscall_lock should be held (protects anonblock_list). 93 */ 94 int 95 uvm_anon_add(count) 96 int count; 97 { 98 struct uvm_anonblock *anonblock; 99 struct vm_anon *anon; 100 int lcv, needed; 101 102 simple_lock(&uvm.afreelock); 103 uvmexp.nanonneeded += count; 104 needed = uvmexp.nanonneeded - uvmexp.nanon; 105 simple_unlock(&uvm.afreelock); 106 107 if (needed <= 0) { 108 return 0; 109 } 110 anon = (void *)uvm_km_alloc(kernel_map, sizeof(*anon) * needed); 111 if (anon == NULL) { 112 simple_lock(&uvm.afreelock); 113 uvmexp.nanonneeded -= count; 114 simple_unlock(&uvm.afreelock); 115 return ENOMEM; 116 } 117 MALLOC(anonblock, void *, sizeof(*anonblock), M_UVMAMAP, M_WAITOK); 118 119 anonblock->count = needed; 120 anonblock->anons = anon; 121 LIST_INSERT_HEAD(&anonblock_list, anonblock, list); 122 memset(anon, 0, sizeof(*anon) * needed); 123 124 simple_lock(&uvm.afreelock); 125 uvmexp.nanon += needed; 126 uvmexp.nfreeanon += needed; 127 for (lcv = 0; lcv < needed; lcv++) { 128 simple_lock_init(&anon[lcv].an_lock); 129 anon[lcv].u.an_nxt = uvm.afree; 130 uvm.afree = &anon[lcv]; 131 } 132 simple_unlock(&uvm.afreelock); 133 return 0; 134 } 135 136 /* 137 * remove anons from the free pool. 138 */ 139 void 140 uvm_anon_remove(count) 141 int count; 142 { 143 /* 144 * we never actually free any anons, to avoid allocation overhead. 145 * XXX someday we might want to try to free anons. 146 */ 147 148 simple_lock(&uvm.afreelock); 149 uvmexp.nanonneeded -= count; 150 simple_unlock(&uvm.afreelock); 151 } 152 153 /* 154 * allocate an anon 155 * 156 * => new anon is returned locked! 157 */ 158 struct vm_anon * 159 uvm_analloc() 160 { 161 struct vm_anon *a; 162 163 simple_lock(&uvm.afreelock); 164 a = uvm.afree; 165 if (a) { 166 uvm.afree = a->u.an_nxt; 167 uvmexp.nfreeanon--; 168 a->an_ref = 1; 169 a->an_swslot = 0; 170 a->u.an_page = NULL; /* so we can free quickly */ 171 LOCK_ASSERT(simple_lock_held(&a->an_lock) == 0); 172 simple_lock(&a->an_lock); 173 } 174 simple_unlock(&uvm.afreelock); 175 return(a); 176 } 177 178 /* 179 * uvm_anfree: free a single anon structure 180 * 181 * => caller must remove anon from its amap before calling (if it was in 182 * an amap). 183 * => anon must be unlocked and have a zero reference count. 184 * => we may lock the pageq's. 185 */ 186 187 void 188 uvm_anfree(anon) 189 struct vm_anon *anon; 190 { 191 struct vm_page *pg; 192 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 193 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 194 195 KASSERT(anon->an_ref == 0); 196 LOCK_ASSERT(!simple_lock_held(&anon->an_lock)); 197 198 /* 199 * get page 200 */ 201 202 pg = anon->u.an_page; 203 204 /* 205 * if there is a resident page and it is loaned, then anon may not 206 * own it. call out to uvm_anon_lockpage() to ensure the real owner 207 * of the page has been identified and locked. 208 */ 209 210 if (pg && pg->loan_count) { 211 simple_lock(&anon->an_lock); 212 pg = uvm_anon_lockloanpg(anon); 213 simple_unlock(&anon->an_lock); 214 } 215 216 /* 217 * if we have a resident page, we must dispose of it before freeing 218 * the anon. 219 */ 220 221 if (pg) { 222 223 /* 224 * if the page is owned by a uobject (now locked), then we must 225 * kill the loan on the page rather than free it. 226 */ 227 228 if (pg->uobject) { 229 uvm_lock_pageq(); 230 KASSERT(pg->loan_count > 0); 231 pg->loan_count--; 232 pg->uanon = NULL; 233 uvm_unlock_pageq(); 234 simple_unlock(&pg->uobject->vmobjlock); 235 } else { 236 237 /* 238 * page has no uobject, so we must be the owner of it. 239 * if page is busy then we wait until it is not busy, 240 * and then free it. 241 */ 242 243 KASSERT((pg->flags & PG_RELEASED) == 0); 244 simple_lock(&anon->an_lock); 245 pmap_page_protect(pg, VM_PROT_NONE); 246 while ((pg = anon->u.an_page) && 247 (pg->flags & PG_BUSY) != 0) { 248 pg->flags |= PG_WANTED; 249 UVM_UNLOCK_AND_WAIT(pg, &anon->an_lock, 0, 250 "anfree", 0); 251 simple_lock(&anon->an_lock); 252 } 253 if (pg) { 254 uvm_lock_pageq(); 255 uvm_pagefree(pg); 256 uvm_unlock_pageq(); 257 } 258 simple_unlock(&anon->an_lock); 259 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 260 "freed now!", anon, pg, 0, 0); 261 } 262 } 263 if (pg == NULL && anon->an_swslot > 0) { 264 /* this page is no longer only in swap. */ 265 simple_lock(&uvm.swap_data_lock); 266 KASSERT(uvmexp.swpgonly > 0); 267 uvmexp.swpgonly--; 268 simple_unlock(&uvm.swap_data_lock); 269 } 270 271 /* 272 * free any swap resources. 273 */ 274 275 uvm_anon_dropswap(anon); 276 277 /* 278 * now that we've stripped the data areas from the anon, 279 * free the anon itself. 280 */ 281 282 simple_lock(&uvm.afreelock); 283 anon->u.an_nxt = uvm.afree; 284 uvm.afree = anon; 285 uvmexp.nfreeanon++; 286 simple_unlock(&uvm.afreelock); 287 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 288 } 289 290 /* 291 * uvm_anon_dropswap: release any swap resources from this anon. 292 * 293 * => anon must be locked or have a reference count of 0. 294 */ 295 void 296 uvm_anon_dropswap(anon) 297 struct vm_anon *anon; 298 { 299 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 300 301 if (anon->an_swslot == 0) 302 return; 303 304 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 305 anon, anon->an_swslot, 0, 0); 306 uvm_swap_free(anon->an_swslot, 1); 307 anon->an_swslot = 0; 308 } 309 310 /* 311 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 312 * 313 * => anon is locked by caller 314 * => on return: anon is locked 315 * if there is a resident page: 316 * if it has a uobject, it is locked by us 317 * if it is ownerless, we take over as owner 318 * we return the resident page (it can change during 319 * this function) 320 * => note that the only time an anon has an ownerless resident page 321 * is if the page was loaned from a uvm_object and the uvm_object 322 * disowned it 323 * => this only needs to be called when you want to do an operation 324 * on an anon's resident page and that page has a non-zero loan 325 * count. 326 */ 327 struct vm_page * 328 uvm_anon_lockloanpg(anon) 329 struct vm_anon *anon; 330 { 331 struct vm_page *pg; 332 boolean_t locked = FALSE; 333 334 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 335 336 /* 337 * loop while we have a resident page that has a non-zero loan count. 338 * if we successfully get our lock, we will "break" the loop. 339 * note that the test for pg->loan_count is not protected -- this 340 * may produce false positive results. note that a false positive 341 * result may cause us to do more work than we need to, but it will 342 * not produce an incorrect result. 343 */ 344 345 while (((pg = anon->u.an_page) != NULL) && pg->loan_count != 0) { 346 347 /* 348 * quickly check to see if the page has an object before 349 * bothering to lock the page queues. this may also produce 350 * a false positive result, but that's ok because we do a real 351 * check after that. 352 */ 353 354 if (pg->uobject) { 355 uvm_lock_pageq(); 356 if (pg->uobject) { 357 locked = 358 simple_lock_try(&pg->uobject->vmobjlock); 359 } else { 360 /* object disowned before we got PQ lock */ 361 locked = TRUE; 362 } 363 uvm_unlock_pageq(); 364 365 /* 366 * if we didn't get a lock (try lock failed), then we 367 * toggle our anon lock and try again 368 */ 369 370 if (!locked) { 371 simple_unlock(&anon->an_lock); 372 373 /* 374 * someone locking the object has a chance to 375 * lock us right now 376 */ 377 378 simple_lock(&anon->an_lock); 379 continue; 380 } 381 } 382 383 /* 384 * if page is un-owned [i.e. the object dropped its ownership], 385 * then we can take over as owner! 386 */ 387 388 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 389 uvm_lock_pageq(); 390 pg->pqflags |= PQ_ANON; 391 pg->loan_count--; 392 uvm_unlock_pageq(); 393 } 394 break; 395 } 396 return(pg); 397 } 398 399 400 401 /* 402 * page in every anon that is paged out to a range of swslots. 403 * 404 * swap_syscall_lock should be held (protects anonblock_list). 405 */ 406 407 boolean_t 408 anon_swap_off(startslot, endslot) 409 int startslot, endslot; 410 { 411 struct uvm_anonblock *anonblock; 412 413 LIST_FOREACH(anonblock, &anonblock_list, list) { 414 int i; 415 416 /* 417 * loop thru all the anons in the anonblock, 418 * paging in where needed. 419 */ 420 421 for (i = 0; i < anonblock->count; i++) { 422 struct vm_anon *anon = &anonblock->anons[i]; 423 int slot; 424 425 /* 426 * lock anon to work on it. 427 */ 428 429 simple_lock(&anon->an_lock); 430 431 /* 432 * is this anon's swap slot in range? 433 */ 434 435 slot = anon->an_swslot; 436 if (slot >= startslot && slot < endslot) { 437 boolean_t rv; 438 439 /* 440 * yup, page it in. 441 */ 442 443 /* locked: anon */ 444 rv = anon_pagein(anon); 445 /* unlocked: anon */ 446 447 if (rv) { 448 return rv; 449 } 450 } else { 451 452 /* 453 * nope, unlock and proceed. 454 */ 455 456 simple_unlock(&anon->an_lock); 457 } 458 } 459 } 460 return FALSE; 461 } 462 463 464 /* 465 * fetch an anon's page. 466 * 467 * => anon must be locked, and is unlocked upon return. 468 * => returns TRUE if pagein was aborted due to lack of memory. 469 */ 470 471 static boolean_t 472 anon_pagein(anon) 473 struct vm_anon *anon; 474 { 475 struct vm_page *pg; 476 struct uvm_object *uobj; 477 int rv; 478 479 /* locked: anon */ 480 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 481 482 rv = uvmfault_anonget(NULL, NULL, anon); 483 484 /* 485 * if rv == 0, anon is still locked, else anon 486 * is unlocked 487 */ 488 489 switch (rv) { 490 case 0: 491 break; 492 493 case EIO: 494 case ERESTART: 495 496 /* 497 * nothing more to do on errors. 498 * ERESTART can only mean that the anon was freed, 499 * so again there's nothing to do. 500 */ 501 502 return FALSE; 503 504 default: 505 return TRUE; 506 } 507 508 /* 509 * ok, we've got the page now. 510 * mark it as dirty, clear its swslot and un-busy it. 511 */ 512 513 pg = anon->u.an_page; 514 uobj = pg->uobject; 515 if (anon->an_swslot > 0) 516 uvm_swap_free(anon->an_swslot, 1); 517 anon->an_swslot = 0; 518 pg->flags &= ~(PG_CLEAN); 519 520 /* 521 * deactivate the page (to put it on a page queue) 522 */ 523 524 pmap_clear_reference(pg); 525 uvm_lock_pageq(); 526 if (pg->wire_count == 0) 527 uvm_pagedeactivate(pg); 528 uvm_unlock_pageq(); 529 530 if (pg->flags & PG_WANTED) { 531 wakeup(pg); 532 pg->flags &= ~(PG_WANTED); 533 } 534 535 /* 536 * unlock the anon and we're done. 537 */ 538 539 simple_unlock(&anon->an_lock); 540 if (uobj) { 541 simple_unlock(&uobj->vmobjlock); 542 } 543 return FALSE; 544 } 545