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 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 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 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 * 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 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 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 * 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 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 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