1 /* $NetBSD: uvm_anon.c,v 1.22 2002/09/21 06:16:07 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 1.22 2002/09/21 06:16:07 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->an_lock); 129 anon[lcv].u.an_nxt = uvm.afree; 130 uvm.afree = &anon[lcv]; 131 simple_lock_init(&uvm.afree->an_lock); 132 } 133 simple_unlock(&uvm.afreelock); 134 return 0; 135 } 136 137 /* 138 * remove anons from the free pool. 139 */ 140 void 141 uvm_anon_remove(count) 142 int count; 143 { 144 /* 145 * we never actually free any anons, to avoid allocation overhead. 146 * XXX someday we might want to try to free anons. 147 */ 148 149 simple_lock(&uvm.afreelock); 150 uvmexp.nanonneeded -= count; 151 simple_unlock(&uvm.afreelock); 152 } 153 154 /* 155 * allocate an anon 156 * 157 * => new anon is returned locked! 158 */ 159 struct vm_anon * 160 uvm_analloc() 161 { 162 struct vm_anon *a; 163 164 simple_lock(&uvm.afreelock); 165 a = uvm.afree; 166 if (a) { 167 uvm.afree = a->u.an_nxt; 168 uvmexp.nfreeanon--; 169 a->an_ref = 1; 170 a->an_swslot = 0; 171 a->u.an_page = NULL; /* so we can free quickly */ 172 LOCK_ASSERT(simple_lock_held(&a->an_lock) == 0); 173 simple_lock(&a->an_lock); 174 } 175 simple_unlock(&uvm.afreelock); 176 return(a); 177 } 178 179 /* 180 * uvm_anfree: free a single anon structure 181 * 182 * => caller must remove anon from its amap before calling (if it was in 183 * an amap). 184 * => anon must be unlocked and have a zero reference count. 185 * => we may lock the pageq's. 186 */ 187 188 void 189 uvm_anfree(anon) 190 struct vm_anon *anon; 191 { 192 struct vm_page *pg; 193 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 194 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 195 196 KASSERT(anon->an_ref == 0); 197 LOCK_ASSERT(!simple_lock_held(&anon->an_lock)); 198 199 /* 200 * get page 201 */ 202 203 pg = anon->u.an_page; 204 205 /* 206 * if there is a resident page and it is loaned, then anon may not 207 * own it. call out to uvm_anon_lockpage() to ensure the real owner 208 * of the page has been identified and locked. 209 */ 210 211 if (pg && pg->loan_count) { 212 simple_lock(&anon->an_lock); 213 pg = uvm_anon_lockloanpg(anon); 214 simple_unlock(&anon->an_lock); 215 } 216 217 /* 218 * if we have a resident page, we must dispose of it before freeing 219 * the anon. 220 */ 221 222 if (pg) { 223 224 /* 225 * if the page is owned by a uobject (now locked), then we must 226 * kill the loan on the page rather than free it. 227 */ 228 229 if (pg->uobject) { 230 uvm_lock_pageq(); 231 KASSERT(pg->loan_count > 0); 232 pg->loan_count--; 233 pg->uanon = NULL; 234 uvm_unlock_pageq(); 235 simple_unlock(&pg->uobject->vmobjlock); 236 } else { 237 238 /* 239 * page has no uobject, so we must be the owner of it. 240 * if page is busy then we wait until it is not busy, 241 * and then free it. 242 */ 243 244 KASSERT((pg->flags & PG_RELEASED) == 0); 245 simple_lock(&anon->an_lock); 246 pmap_page_protect(pg, VM_PROT_NONE); 247 while ((pg = anon->u.an_page) && 248 (pg->flags & PG_BUSY) != 0) { 249 pg->flags |= PG_WANTED; 250 UVM_UNLOCK_AND_WAIT(pg, &anon->an_lock, 0, 251 "anfree", 0); 252 simple_lock(&anon->an_lock); 253 } 254 if (pg) { 255 uvm_lock_pageq(); 256 uvm_pagefree(pg); 257 uvm_unlock_pageq(); 258 } 259 simple_unlock(&anon->an_lock); 260 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 261 "freed now!", anon, pg, 0, 0); 262 } 263 } 264 if (pg == NULL && anon->an_swslot != 0) { 265 /* this page is no longer only in swap. */ 266 simple_lock(&uvm.swap_data_lock); 267 KASSERT(uvmexp.swpgonly > 0); 268 uvmexp.swpgonly--; 269 simple_unlock(&uvm.swap_data_lock); 270 } 271 272 /* 273 * free any swap resources. 274 */ 275 276 uvm_anon_dropswap(anon); 277 278 /* 279 * now that we've stripped the data areas from the anon, 280 * free the anon itself. 281 */ 282 283 simple_lock(&uvm.afreelock); 284 anon->u.an_nxt = uvm.afree; 285 uvm.afree = anon; 286 uvmexp.nfreeanon++; 287 simple_unlock(&uvm.afreelock); 288 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 289 } 290 291 /* 292 * uvm_anon_dropswap: release any swap resources from this anon. 293 * 294 * => anon must be locked or have a reference count of 0. 295 */ 296 void 297 uvm_anon_dropswap(anon) 298 struct vm_anon *anon; 299 { 300 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 301 302 if (anon->an_swslot == 0) 303 return; 304 305 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 306 anon, anon->an_swslot, 0, 0); 307 uvm_swap_free(anon->an_swslot, 1); 308 anon->an_swslot = 0; 309 } 310 311 /* 312 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 313 * 314 * => anon is locked by caller 315 * => on return: anon is locked 316 * if there is a resident page: 317 * if it has a uobject, it is locked by us 318 * if it is ownerless, we take over as owner 319 * we return the resident page (it can change during 320 * this function) 321 * => note that the only time an anon has an ownerless resident page 322 * is if the page was loaned from a uvm_object and the uvm_object 323 * disowned it 324 * => this only needs to be called when you want to do an operation 325 * on an anon's resident page and that page has a non-zero loan 326 * count. 327 */ 328 struct vm_page * 329 uvm_anon_lockloanpg(anon) 330 struct vm_anon *anon; 331 { 332 struct vm_page *pg; 333 boolean_t locked = FALSE; 334 335 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 336 337 /* 338 * loop while we have a resident page that has a non-zero loan count. 339 * if we successfully get our lock, we will "break" the loop. 340 * note that the test for pg->loan_count is not protected -- this 341 * may produce false positive results. note that a false positive 342 * result may cause us to do more work than we need to, but it will 343 * not produce an incorrect result. 344 */ 345 346 while (((pg = anon->u.an_page) != NULL) && pg->loan_count != 0) { 347 348 /* 349 * quickly check to see if the page has an object before 350 * bothering to lock the page queues. this may also produce 351 * a false positive result, but that's ok because we do a real 352 * check after that. 353 */ 354 355 if (pg->uobject) { 356 uvm_lock_pageq(); 357 if (pg->uobject) { 358 locked = 359 simple_lock_try(&pg->uobject->vmobjlock); 360 } else { 361 /* object disowned before we got PQ lock */ 362 locked = TRUE; 363 } 364 uvm_unlock_pageq(); 365 366 /* 367 * if we didn't get a lock (try lock failed), then we 368 * toggle our anon lock and try again 369 */ 370 371 if (!locked) { 372 simple_unlock(&anon->an_lock); 373 374 /* 375 * someone locking the object has a chance to 376 * lock us right now 377 */ 378 379 simple_lock(&anon->an_lock); 380 continue; 381 } 382 } 383 384 /* 385 * if page is un-owned [i.e. the object dropped its ownership], 386 * then we can take over as owner! 387 */ 388 389 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 390 uvm_lock_pageq(); 391 pg->pqflags |= PQ_ANON; 392 pg->loan_count--; 393 uvm_unlock_pageq(); 394 } 395 break; 396 } 397 return(pg); 398 } 399 400 401 402 /* 403 * page in every anon that is paged out to a range of swslots. 404 * 405 * swap_syscall_lock should be held (protects anonblock_list). 406 */ 407 408 boolean_t 409 anon_swap_off(startslot, endslot) 410 int startslot, endslot; 411 { 412 struct uvm_anonblock *anonblock; 413 414 LIST_FOREACH(anonblock, &anonblock_list, list) { 415 int i; 416 417 /* 418 * loop thru all the anons in the anonblock, 419 * paging in where needed. 420 */ 421 422 for (i = 0; i < anonblock->count; i++) { 423 struct vm_anon *anon = &anonblock->anons[i]; 424 int slot; 425 426 /* 427 * lock anon to work on it. 428 */ 429 430 simple_lock(&anon->an_lock); 431 432 /* 433 * is this anon's swap slot in range? 434 */ 435 436 slot = anon->an_swslot; 437 if (slot >= startslot && slot < endslot) { 438 boolean_t rv; 439 440 /* 441 * yup, page it in. 442 */ 443 444 /* locked: anon */ 445 rv = anon_pagein(anon); 446 /* unlocked: anon */ 447 448 if (rv) { 449 return rv; 450 } 451 } else { 452 453 /* 454 * nope, unlock and proceed. 455 */ 456 457 simple_unlock(&anon->an_lock); 458 } 459 } 460 } 461 return FALSE; 462 } 463 464 465 /* 466 * fetch an anon's page. 467 * 468 * => anon must be locked, and is unlocked upon return. 469 * => returns TRUE if pagein was aborted due to lack of memory. 470 */ 471 472 static boolean_t 473 anon_pagein(anon) 474 struct vm_anon *anon; 475 { 476 struct vm_page *pg; 477 struct uvm_object *uobj; 478 int rv; 479 480 /* locked: anon */ 481 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 482 483 rv = uvmfault_anonget(NULL, NULL, anon); 484 485 /* 486 * if rv == 0, anon is still locked, else anon 487 * is unlocked 488 */ 489 490 switch (rv) { 491 case 0: 492 break; 493 494 case EIO: 495 case ERESTART: 496 497 /* 498 * nothing more to do on errors. 499 * ERESTART can only mean that the anon was freed, 500 * so again there's nothing to do. 501 */ 502 503 return FALSE; 504 } 505 506 /* 507 * ok, we've got the page now. 508 * mark it as dirty, clear its swslot and un-busy it. 509 */ 510 511 pg = anon->u.an_page; 512 uobj = pg->uobject; 513 uvm_swap_free(anon->an_swslot, 1); 514 anon->an_swslot = 0; 515 pg->flags &= ~(PG_CLEAN); 516 517 /* 518 * deactivate the page (to put it on a page queue) 519 */ 520 521 pmap_clear_reference(pg); 522 uvm_lock_pageq(); 523 uvm_pagedeactivate(pg); 524 uvm_unlock_pageq(); 525 526 /* 527 * unlock the anon and we're done. 528 */ 529 530 simple_unlock(&anon->an_lock); 531 if (uobj) { 532 simple_unlock(&uobj->vmobjlock); 533 } 534 return FALSE; 535 } 536