1 /* $NetBSD: uvm_anon.c,v 1.48 2007/11/13 08:48:28 yamt 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 1.48 2007/11/13 08:48:28 yamt 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 #include <uvm/uvm_pdpolicy.h> 54 55 static struct pool_cache uvm_anon_cache; 56 57 static int uvm_anon_ctor(void *, void *, int); 58 static void uvm_anon_dtor(void *, void *); 59 60 /* 61 * allocate anons 62 */ 63 void 64 uvm_anon_init(void) 65 { 66 67 pool_cache_bootstrap(&uvm_anon_cache, sizeof(struct vm_anon), 0, 0, 0, 68 "anonpl", NULL, IPL_NONE, uvm_anon_ctor, uvm_anon_dtor, NULL); 69 } 70 71 static int 72 uvm_anon_ctor(void *arg, void *object, int flags) 73 { 74 struct vm_anon *anon = object; 75 76 anon->an_ref = 0; 77 simple_lock_init(&anon->an_lock); 78 anon->an_page = NULL; 79 #if defined(VMSWAP) 80 anon->an_swslot = 0; 81 #endif /* defined(VMSWAP) */ 82 83 return 0; 84 } 85 86 static void 87 uvm_anon_dtor(void *arg, void *object) 88 { 89 90 /* nothing yet */ 91 } 92 93 /* 94 * allocate an anon 95 * 96 * => new anon is returned locked! 97 */ 98 struct vm_anon * 99 uvm_analloc(void) 100 { 101 struct vm_anon *anon; 102 103 anon = pool_cache_get(&uvm_anon_cache, PR_NOWAIT); 104 if (anon) { 105 KASSERT(anon->an_ref == 0); 106 LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); 107 KASSERT(anon->an_page == NULL); 108 #if defined(VMSWAP) 109 KASSERT(anon->an_swslot == 0); 110 #endif /* defined(VMSWAP) */ 111 anon->an_ref = 1; 112 simple_lock(&anon->an_lock); 113 } 114 return anon; 115 } 116 117 /* 118 * uvm_anfree: free a single anon structure 119 * 120 * => caller must remove anon from its amap before calling (if it was in 121 * an amap). 122 * => anon must be unlocked and have a zero reference count. 123 * => we may lock the pageq's. 124 */ 125 126 void 127 uvm_anfree(struct vm_anon *anon) 128 { 129 struct vm_page *pg; 130 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 131 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 132 133 KASSERT(anon->an_ref == 0); 134 135 /* 136 * get page 137 */ 138 139 pg = anon->an_page; 140 141 /* 142 * if there is a resident page and it is loaned, then anon may not 143 * own it. call out to uvm_anon_lockpage() to ensure the real owner 144 * of the page has been identified and locked. 145 */ 146 147 if (pg && pg->loan_count) { 148 simple_lock(&anon->an_lock); 149 pg = uvm_anon_lockloanpg(anon); 150 simple_unlock(&anon->an_lock); 151 } 152 153 /* 154 * if we have a resident page, we must dispose of it before freeing 155 * the anon. 156 */ 157 158 if (pg) { 159 160 /* 161 * if the page is owned by a uobject (now locked), then we must 162 * kill the loan on the page rather than free it. 163 */ 164 165 if (pg->uobject) { 166 uvm_lock_pageq(); 167 KASSERT(pg->loan_count > 0); 168 pg->loan_count--; 169 pg->uanon = NULL; 170 uvm_unlock_pageq(); 171 simple_unlock(&pg->uobject->vmobjlock); 172 } else { 173 174 /* 175 * page has no uobject, so we must be the owner of it. 176 */ 177 178 KASSERT((pg->flags & PG_RELEASED) == 0); 179 simple_lock(&anon->an_lock); 180 pmap_page_protect(pg, VM_PROT_NONE); 181 182 /* 183 * if the page is busy, mark it as PG_RELEASED 184 * so that uvm_anon_release will release it later. 185 */ 186 187 if (pg->flags & PG_BUSY) { 188 pg->flags |= PG_RELEASED; 189 simple_unlock(&anon->an_lock); 190 return; 191 } 192 uvm_lock_pageq(); 193 uvm_pagefree(pg); 194 uvm_unlock_pageq(); 195 simple_unlock(&anon->an_lock); 196 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 197 "freed now!", anon, pg, 0, 0); 198 } 199 } 200 #if defined(VMSWAP) 201 if (pg == NULL && anon->an_swslot > 0) { 202 /* this page is no longer only in swap. */ 203 mutex_enter(&uvm_swap_data_lock); 204 KASSERT(uvmexp.swpgonly > 0); 205 uvmexp.swpgonly--; 206 mutex_exit(&uvm_swap_data_lock); 207 } 208 #endif /* defined(VMSWAP) */ 209 210 /* 211 * free any swap resources. 212 */ 213 214 uvm_anon_dropswap(anon); 215 216 /* 217 * give a page replacement hint. 218 */ 219 220 uvmpdpol_anfree(anon); 221 222 /* 223 * now that we've stripped the data areas from the anon, 224 * free the anon itself. 225 */ 226 227 KASSERT(anon->an_page == NULL); 228 #if defined(VMSWAP) 229 KASSERT(anon->an_swslot == 0); 230 #endif /* defined(VMSWAP) */ 231 232 pool_cache_put(&uvm_anon_cache, anon); 233 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 234 } 235 236 #if defined(VMSWAP) 237 238 /* 239 * uvm_anon_dropswap: release any swap resources from this anon. 240 * 241 * => anon must be locked or have a reference count of 0. 242 */ 243 void 244 uvm_anon_dropswap(struct vm_anon *anon) 245 { 246 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 247 248 if (anon->an_swslot == 0) 249 return; 250 251 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 252 anon, anon->an_swslot, 0, 0); 253 uvm_swap_free(anon->an_swslot, 1); 254 anon->an_swslot = 0; 255 } 256 257 #endif /* defined(VMSWAP) */ 258 259 /* 260 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 261 * 262 * => anon is locked by caller 263 * => on return: anon is locked 264 * if there is a resident page: 265 * if it has a uobject, it is locked by us 266 * if it is ownerless, we take over as owner 267 * we return the resident page (it can change during 268 * this function) 269 * => note that the only time an anon has an ownerless resident page 270 * is if the page was loaned from a uvm_object and the uvm_object 271 * disowned it 272 * => this only needs to be called when you want to do an operation 273 * on an anon's resident page and that page has a non-zero loan 274 * count. 275 */ 276 struct vm_page * 277 uvm_anon_lockloanpg(struct vm_anon *anon) 278 { 279 struct vm_page *pg; 280 bool locked = false; 281 282 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 283 284 /* 285 * loop while we have a resident page that has a non-zero loan count. 286 * if we successfully get our lock, we will "break" the loop. 287 * note that the test for pg->loan_count is not protected -- this 288 * may produce false positive results. note that a false positive 289 * result may cause us to do more work than we need to, but it will 290 * not produce an incorrect result. 291 */ 292 293 while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) { 294 295 /* 296 * quickly check to see if the page has an object before 297 * bothering to lock the page queues. this may also produce 298 * a false positive result, but that's ok because we do a real 299 * check after that. 300 */ 301 302 if (pg->uobject) { 303 uvm_lock_pageq(); 304 if (pg->uobject) { 305 locked = 306 simple_lock_try(&pg->uobject->vmobjlock); 307 } else { 308 /* object disowned before we got PQ lock */ 309 locked = true; 310 } 311 uvm_unlock_pageq(); 312 313 /* 314 * if we didn't get a lock (try lock failed), then we 315 * toggle our anon lock and try again 316 */ 317 318 if (!locked) { 319 simple_unlock(&anon->an_lock); 320 321 /* 322 * someone locking the object has a chance to 323 * lock us right now 324 */ 325 326 simple_lock(&anon->an_lock); 327 continue; 328 } 329 } 330 331 /* 332 * if page is un-owned [i.e. the object dropped its ownership], 333 * then we can take over as owner! 334 */ 335 336 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 337 uvm_lock_pageq(); 338 pg->pqflags |= PQ_ANON; 339 pg->loan_count--; 340 uvm_unlock_pageq(); 341 } 342 break; 343 } 344 return(pg); 345 } 346 347 #if defined(VMSWAP) 348 349 /* 350 * fetch an anon's page. 351 * 352 * => anon must be locked, and is unlocked upon return. 353 * => returns true if pagein was aborted due to lack of memory. 354 */ 355 356 bool 357 uvm_anon_pagein(struct vm_anon *anon) 358 { 359 struct vm_page *pg; 360 struct uvm_object *uobj; 361 int rv; 362 363 /* locked: anon */ 364 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 365 366 rv = uvmfault_anonget(NULL, NULL, anon); 367 368 /* 369 * if rv == 0, anon is still locked, else anon 370 * is unlocked 371 */ 372 373 switch (rv) { 374 case 0: 375 break; 376 377 case EIO: 378 case ERESTART: 379 380 /* 381 * nothing more to do on errors. 382 * ERESTART can only mean that the anon was freed, 383 * so again there's nothing to do. 384 */ 385 386 return false; 387 388 default: 389 return true; 390 } 391 392 /* 393 * ok, we've got the page now. 394 * mark it as dirty, clear its swslot and un-busy it. 395 */ 396 397 pg = anon->an_page; 398 uobj = pg->uobject; 399 if (anon->an_swslot > 0) 400 uvm_swap_free(anon->an_swslot, 1); 401 anon->an_swslot = 0; 402 pg->flags &= ~(PG_CLEAN); 403 404 /* 405 * deactivate the page (to put it on a page queue) 406 */ 407 408 pmap_clear_reference(pg); 409 uvm_lock_pageq(); 410 if (pg->wire_count == 0) 411 uvm_pagedeactivate(pg); 412 uvm_unlock_pageq(); 413 414 if (pg->flags & PG_WANTED) { 415 wakeup(pg); 416 pg->flags &= ~(PG_WANTED); 417 } 418 419 /* 420 * unlock the anon and we're done. 421 */ 422 423 simple_unlock(&anon->an_lock); 424 if (uobj) { 425 simple_unlock(&uobj->vmobjlock); 426 } 427 return false; 428 } 429 430 #endif /* defined(VMSWAP) */ 431 432 /* 433 * uvm_anon_release: release an anon and its page. 434 * 435 * => caller must lock the anon. 436 */ 437 438 void 439 uvm_anon_release(struct vm_anon *anon) 440 { 441 struct vm_page *pg = anon->an_page; 442 443 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 444 445 KASSERT(pg != NULL); 446 KASSERT((pg->flags & PG_RELEASED) != 0); 447 KASSERT((pg->flags & PG_BUSY) != 0); 448 KASSERT(pg->uobject == NULL); 449 KASSERT(pg->uanon == anon); 450 KASSERT(pg->loan_count == 0); 451 KASSERT(anon->an_ref == 0); 452 453 uvm_lock_pageq(); 454 uvm_pagefree(pg); 455 uvm_unlock_pageq(); 456 simple_unlock(&anon->an_lock); 457 458 KASSERT(anon->an_page == NULL); 459 460 uvm_anfree(anon); 461 } 462