1 /* $NetBSD: uvm_anon.c,v 1.17 2001/05/25 04:06:12 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 "opt_uvmhist.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/proc.h> 44 #include <sys/malloc.h> 45 #include <sys/pool.h> 46 #include <sys/kernel.h> 47 48 #include <uvm/uvm.h> 49 #include <uvm/uvm_swap.h> 50 51 /* 52 * anonblock_list: global list of anon blocks, 53 * locked by swap_syscall_lock (since we never remove 54 * anything from this list and we only add to it via swapctl(2)). 55 */ 56 57 struct uvm_anonblock { 58 LIST_ENTRY(uvm_anonblock) list; 59 int count; 60 struct vm_anon *anons; 61 }; 62 static LIST_HEAD(anonlist, uvm_anonblock) anonblock_list; 63 64 65 static boolean_t anon_pagein __P((struct vm_anon *)); 66 67 68 /* 69 * allocate anons 70 */ 71 void 72 uvm_anon_init() 73 { 74 int nanon = uvmexp.free - (uvmexp.free / 16); /* XXXCDC ??? */ 75 76 simple_lock_init(&uvm.afreelock); 77 LIST_INIT(&anonblock_list); 78 79 /* 80 * Allocate the initial anons. 81 */ 82 uvm_anon_add(nanon); 83 } 84 85 /* 86 * add some more anons to the free pool. called when we add 87 * more swap space. 88 * 89 * => swap_syscall_lock should be held (protects anonblock_list). 90 */ 91 int 92 uvm_anon_add(count) 93 int count; 94 { 95 struct uvm_anonblock *anonblock; 96 struct vm_anon *anon; 97 int lcv, needed; 98 99 simple_lock(&uvm.afreelock); 100 uvmexp.nanonneeded += count; 101 needed = uvmexp.nanonneeded - uvmexp.nanon; 102 simple_unlock(&uvm.afreelock); 103 104 if (needed <= 0) { 105 return 0; 106 } 107 anon = (void *)uvm_km_alloc(kernel_map, sizeof(*anon) * needed); 108 if (anon == NULL) { 109 simple_lock(&uvm.afreelock); 110 uvmexp.nanonneeded -= count; 111 simple_unlock(&uvm.afreelock); 112 return ENOMEM; 113 } 114 MALLOC(anonblock, void *, sizeof(*anonblock), M_UVMAMAP, M_WAITOK); 115 116 anonblock->count = needed; 117 anonblock->anons = anon; 118 LIST_INSERT_HEAD(&anonblock_list, anonblock, list); 119 memset(anon, 0, sizeof(*anon) * needed); 120 121 simple_lock(&uvm.afreelock); 122 uvmexp.nanon += needed; 123 uvmexp.nfreeanon += needed; 124 for (lcv = 0; lcv < needed; lcv++) { 125 simple_lock_init(&anon->an_lock); 126 anon[lcv].u.an_nxt = uvm.afree; 127 uvm.afree = &anon[lcv]; 128 simple_lock_init(&uvm.afree->an_lock); 129 } 130 simple_unlock(&uvm.afreelock); 131 return 0; 132 } 133 134 /* 135 * remove anons from the free pool. 136 */ 137 void 138 uvm_anon_remove(count) 139 int count; 140 { 141 /* 142 * we never actually free any anons, to avoid allocation overhead. 143 * XXX someday we might want to try to free anons. 144 */ 145 146 simple_lock(&uvm.afreelock); 147 uvmexp.nanonneeded -= count; 148 simple_unlock(&uvm.afreelock); 149 } 150 151 /* 152 * allocate an anon 153 * 154 * => new anon is returned locked! 155 */ 156 struct vm_anon * 157 uvm_analloc() 158 { 159 struct vm_anon *a; 160 161 simple_lock(&uvm.afreelock); 162 a = uvm.afree; 163 if (a) { 164 uvm.afree = a->u.an_nxt; 165 uvmexp.nfreeanon--; 166 a->an_ref = 1; 167 a->an_swslot = 0; 168 a->u.an_page = NULL; /* so we can free quickly */ 169 LOCK_ASSERT(simple_lock_held(&a->an_lock) == 0); 170 simple_lock(&a->an_lock); 171 } 172 simple_unlock(&uvm.afreelock); 173 return(a); 174 } 175 176 /* 177 * uvm_anfree: free a single anon structure 178 * 179 * => caller must remove anon from its amap before calling (if it was in 180 * an amap). 181 * => anon must be unlocked and have a zero reference count. 182 * => we may lock the pageq's. 183 */ 184 void 185 uvm_anfree(anon) 186 struct vm_anon *anon; 187 { 188 struct vm_page *pg; 189 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 190 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 191 192 KASSERT(anon->an_ref == 0); 193 LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); 194 195 /* 196 * get page 197 */ 198 199 pg = anon->u.an_page; 200 201 /* 202 * if there is a resident page and it is loaned, then anon may not 203 * own it. call out to uvm_anon_lockpage() to ensure the real owner 204 * of the page has been identified and locked. 205 */ 206 207 if (pg && pg->loan_count) 208 pg = uvm_anon_lockloanpg(anon); 209 210 /* 211 * if we have a resident page, we must dispose of it before freeing 212 * the anon. 213 */ 214 215 if (pg) { 216 217 /* 218 * if the page is owned by a uobject (now locked), then we must 219 * kill the loan on the page rather than free it. 220 */ 221 222 if (pg->uobject) { 223 uvm_lock_pageq(); 224 KASSERT(pg->loan_count > 0); 225 pg->loan_count--; 226 pg->uanon = NULL; 227 uvm_unlock_pageq(); 228 simple_unlock(&pg->uobject->vmobjlock); 229 } else { 230 231 /* 232 * page has no uobject, so we must be the owner of it. 233 * 234 * if page is busy then we just mark it as released 235 * (who ever has it busy must check for this when they 236 * wake up). if the page is not busy then we can 237 * free it now. 238 */ 239 240 if ((pg->flags & PG_BUSY) != 0) { 241 /* tell them to dump it when done */ 242 pg->flags |= PG_RELEASED; 243 UVMHIST_LOG(maphist, 244 " anon 0x%x, page 0x%x: BUSY (released!)", 245 anon, pg, 0, 0); 246 return; 247 } 248 pmap_page_protect(pg, VM_PROT_NONE); 249 uvm_lock_pageq(); /* lock out pagedaemon */ 250 uvm_pagefree(pg); /* bye bye */ 251 uvm_unlock_pageq(); /* free the daemon */ 252 UVMHIST_LOG(maphist,"anon 0x%x, page 0x%x: freed now!", 253 anon, pg, 0, 0); 254 } 255 } 256 257 /* 258 * free any swap resources. 259 */ 260 uvm_anon_dropswap(anon); 261 262 /* 263 * now that we've stripped the data areas from the anon, free the anon 264 * itself! 265 */ 266 simple_lock(&uvm.afreelock); 267 anon->u.an_nxt = uvm.afree; 268 uvm.afree = anon; 269 uvmexp.nfreeanon++; 270 simple_unlock(&uvm.afreelock); 271 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 272 } 273 274 /* 275 * uvm_anon_dropswap: release any swap resources from this anon. 276 * 277 * => anon must be locked or have a reference count of 0. 278 */ 279 void 280 uvm_anon_dropswap(anon) 281 struct vm_anon *anon; 282 { 283 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 284 285 if (anon->an_swslot == 0) 286 return; 287 288 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 289 anon, anon->an_swslot, 0, 0); 290 uvm_swap_free(anon->an_swslot, 1); 291 anon->an_swslot = 0; 292 293 if (anon->u.an_page == NULL) { 294 /* this page is no longer only in swap. */ 295 simple_lock(&uvm.swap_data_lock); 296 uvmexp.swpgonly--; 297 simple_unlock(&uvm.swap_data_lock); 298 } 299 } 300 301 /* 302 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 303 * 304 * => anon is locked by caller 305 * => on return: anon is locked 306 * if there is a resident page: 307 * if it has a uobject, it is locked by us 308 * if it is ownerless, we take over as owner 309 * we return the resident page (it can change during 310 * this function) 311 * => note that the only time an anon has an ownerless resident page 312 * is if the page was loaned from a uvm_object and the uvm_object 313 * disowned it 314 * => this only needs to be called when you want to do an operation 315 * on an anon's resident page and that page has a non-zero loan 316 * count. 317 */ 318 struct vm_page * 319 uvm_anon_lockloanpg(anon) 320 struct vm_anon *anon; 321 { 322 struct vm_page *pg; 323 boolean_t locked = FALSE; 324 325 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 326 327 /* 328 * loop while we have a resident page that has a non-zero loan count. 329 * if we successfully get our lock, we will "break" the loop. 330 * note that the test for pg->loan_count is not protected -- this 331 * may produce false positive results. note that a false positive 332 * result may cause us to do more work than we need to, but it will 333 * not produce an incorrect result. 334 */ 335 336 while (((pg = anon->u.an_page) != NULL) && pg->loan_count != 0) { 337 338 /* 339 * quickly check to see if the page has an object before 340 * bothering to lock the page queues. this may also produce 341 * a false positive result, but that's ok because we do a real 342 * check after that. 343 * 344 * XXX: quick check -- worth it? need volatile? 345 */ 346 347 if (pg->uobject) { 348 349 uvm_lock_pageq(); 350 if (pg->uobject) { /* the "real" check */ 351 locked = 352 simple_lock_try(&pg->uobject->vmobjlock); 353 } else { 354 /* object disowned before we got PQ lock */ 355 locked = TRUE; 356 } 357 uvm_unlock_pageq(); 358 359 /* 360 * if we didn't get a lock (try lock failed), then we 361 * toggle our anon lock and try again 362 */ 363 364 if (!locked) { 365 simple_unlock(&anon->an_lock); 366 367 /* 368 * someone locking the object has a chance to 369 * lock us right now 370 */ 371 372 simple_lock(&anon->an_lock); 373 continue; 374 } 375 } 376 377 /* 378 * if page is un-owned [i.e. the object dropped its ownership], 379 * then we can take over as owner! 380 */ 381 382 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 383 uvm_lock_pageq(); 384 pg->pqflags |= PQ_ANON; /* take ownership... */ 385 pg->loan_count--; /* ... and drop our loan */ 386 uvm_unlock_pageq(); 387 } 388 389 /* 390 * we did it! break the loop 391 */ 392 393 break; 394 } 395 return(pg); 396 } 397 398 399 400 /* 401 * page in every anon that is paged out to a range of swslots. 402 * 403 * swap_syscall_lock should be held (protects anonblock_list). 404 */ 405 406 boolean_t 407 anon_swap_off(startslot, endslot) 408 int startslot, endslot; 409 { 410 struct uvm_anonblock *anonblock; 411 412 for (anonblock = LIST_FIRST(&anonblock_list); 413 anonblock != NULL; 414 anonblock = LIST_NEXT(anonblock, 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