1 /* $NetBSD: uvm_anon.c,v 1.47 2007/11/07 00:23:46 ad 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 1.47 2007/11/07 00:23:46 ad 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 POOL_INIT(uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 0, "anonpl", 56 &pool_allocator_nointr, IPL_NONE); 57 static struct pool_cache uvm_anon_cache; 58 59 static int uvm_anon_ctor(void *, void *, int); 60 static void uvm_anon_dtor(void *, void *); 61 62 /* 63 * allocate anons 64 */ 65 void 66 uvm_anon_init(void) 67 { 68 69 pool_cache_bootstrap(&uvm_anon_cache, sizeof(struct vm_anon), 0, 0, 0, 70 "anonpl", NULL, IPL_NONE, uvm_anon_ctor, uvm_anon_dtor, NULL); 71 } 72 73 static int 74 uvm_anon_ctor(void *arg, void *object, int flags) 75 { 76 struct vm_anon *anon = object; 77 78 anon->an_ref = 0; 79 simple_lock_init(&anon->an_lock); 80 anon->an_page = NULL; 81 #if defined(VMSWAP) 82 anon->an_swslot = 0; 83 #endif /* defined(VMSWAP) */ 84 85 return 0; 86 } 87 88 static void 89 uvm_anon_dtor(void *arg, void *object) 90 { 91 92 /* nothing yet */ 93 } 94 95 /* 96 * allocate an anon 97 * 98 * => new anon is returned locked! 99 */ 100 struct vm_anon * 101 uvm_analloc(void) 102 { 103 struct vm_anon *anon; 104 105 anon = pool_cache_get(&uvm_anon_cache, PR_NOWAIT); 106 if (anon) { 107 KASSERT(anon->an_ref == 0); 108 LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); 109 KASSERT(anon->an_page == NULL); 110 #if defined(VMSWAP) 111 KASSERT(anon->an_swslot == 0); 112 #endif /* defined(VMSWAP) */ 113 anon->an_ref = 1; 114 simple_lock(&anon->an_lock); 115 } 116 return anon; 117 } 118 119 /* 120 * uvm_anfree: free a single anon structure 121 * 122 * => caller must remove anon from its amap before calling (if it was in 123 * an amap). 124 * => anon must be unlocked and have a zero reference count. 125 * => we may lock the pageq's. 126 */ 127 128 void 129 uvm_anfree(struct vm_anon *anon) 130 { 131 struct vm_page *pg; 132 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 133 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 134 135 KASSERT(anon->an_ref == 0); 136 137 /* 138 * get page 139 */ 140 141 pg = anon->an_page; 142 143 /* 144 * if there is a resident page and it is loaned, then anon may not 145 * own it. call out to uvm_anon_lockpage() to ensure the real owner 146 * of the page has been identified and locked. 147 */ 148 149 if (pg && pg->loan_count) { 150 simple_lock(&anon->an_lock); 151 pg = uvm_anon_lockloanpg(anon); 152 simple_unlock(&anon->an_lock); 153 } 154 155 /* 156 * if we have a resident page, we must dispose of it before freeing 157 * the anon. 158 */ 159 160 if (pg) { 161 162 /* 163 * if the page is owned by a uobject (now locked), then we must 164 * kill the loan on the page rather than free it. 165 */ 166 167 if (pg->uobject) { 168 uvm_lock_pageq(); 169 KASSERT(pg->loan_count > 0); 170 pg->loan_count--; 171 pg->uanon = NULL; 172 uvm_unlock_pageq(); 173 simple_unlock(&pg->uobject->vmobjlock); 174 } else { 175 176 /* 177 * page has no uobject, so we must be the owner of it. 178 */ 179 180 KASSERT((pg->flags & PG_RELEASED) == 0); 181 simple_lock(&anon->an_lock); 182 pmap_page_protect(pg, VM_PROT_NONE); 183 184 /* 185 * if the page is busy, mark it as PG_RELEASED 186 * so that uvm_anon_release will release it later. 187 */ 188 189 if (pg->flags & PG_BUSY) { 190 pg->flags |= PG_RELEASED; 191 simple_unlock(&anon->an_lock); 192 return; 193 } 194 uvm_lock_pageq(); 195 uvm_pagefree(pg); 196 uvm_unlock_pageq(); 197 simple_unlock(&anon->an_lock); 198 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 199 "freed now!", anon, pg, 0, 0); 200 } 201 } 202 #if defined(VMSWAP) 203 if (pg == NULL && anon->an_swslot > 0) { 204 /* this page is no longer only in swap. */ 205 mutex_enter(&uvm_swap_data_lock); 206 KASSERT(uvmexp.swpgonly > 0); 207 uvmexp.swpgonly--; 208 mutex_exit(&uvm_swap_data_lock); 209 } 210 #endif /* defined(VMSWAP) */ 211 212 /* 213 * free any swap resources. 214 */ 215 216 uvm_anon_dropswap(anon); 217 218 /* 219 * give a page replacement hint. 220 */ 221 222 uvmpdpol_anfree(anon); 223 224 /* 225 * now that we've stripped the data areas from the anon, 226 * free the anon itself. 227 */ 228 229 KASSERT(anon->an_page == NULL); 230 #if defined(VMSWAP) 231 KASSERT(anon->an_swslot == 0); 232 #endif /* defined(VMSWAP) */ 233 234 pool_cache_put(&uvm_anon_cache, anon); 235 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 236 } 237 238 #if defined(VMSWAP) 239 240 /* 241 * uvm_anon_dropswap: release any swap resources from this anon. 242 * 243 * => anon must be locked or have a reference count of 0. 244 */ 245 void 246 uvm_anon_dropswap(struct vm_anon *anon) 247 { 248 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 249 250 if (anon->an_swslot == 0) 251 return; 252 253 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 254 anon, anon->an_swslot, 0, 0); 255 uvm_swap_free(anon->an_swslot, 1); 256 anon->an_swslot = 0; 257 } 258 259 #endif /* defined(VMSWAP) */ 260 261 /* 262 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 263 * 264 * => anon is locked by caller 265 * => on return: anon is locked 266 * if there is a resident page: 267 * if it has a uobject, it is locked by us 268 * if it is ownerless, we take over as owner 269 * we return the resident page (it can change during 270 * this function) 271 * => note that the only time an anon has an ownerless resident page 272 * is if the page was loaned from a uvm_object and the uvm_object 273 * disowned it 274 * => this only needs to be called when you want to do an operation 275 * on an anon's resident page and that page has a non-zero loan 276 * count. 277 */ 278 struct vm_page * 279 uvm_anon_lockloanpg(struct vm_anon *anon) 280 { 281 struct vm_page *pg; 282 bool locked = false; 283 284 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 285 286 /* 287 * loop while we have a resident page that has a non-zero loan count. 288 * if we successfully get our lock, we will "break" the loop. 289 * note that the test for pg->loan_count is not protected -- this 290 * may produce false positive results. note that a false positive 291 * result may cause us to do more work than we need to, but it will 292 * not produce an incorrect result. 293 */ 294 295 while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) { 296 297 /* 298 * quickly check to see if the page has an object before 299 * bothering to lock the page queues. this may also produce 300 * a false positive result, but that's ok because we do a real 301 * check after that. 302 */ 303 304 if (pg->uobject) { 305 uvm_lock_pageq(); 306 if (pg->uobject) { 307 locked = 308 simple_lock_try(&pg->uobject->vmobjlock); 309 } else { 310 /* object disowned before we got PQ lock */ 311 locked = true; 312 } 313 uvm_unlock_pageq(); 314 315 /* 316 * if we didn't get a lock (try lock failed), then we 317 * toggle our anon lock and try again 318 */ 319 320 if (!locked) { 321 simple_unlock(&anon->an_lock); 322 323 /* 324 * someone locking the object has a chance to 325 * lock us right now 326 */ 327 328 simple_lock(&anon->an_lock); 329 continue; 330 } 331 } 332 333 /* 334 * if page is un-owned [i.e. the object dropped its ownership], 335 * then we can take over as owner! 336 */ 337 338 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 339 uvm_lock_pageq(); 340 pg->pqflags |= PQ_ANON; 341 pg->loan_count--; 342 uvm_unlock_pageq(); 343 } 344 break; 345 } 346 return(pg); 347 } 348 349 #if defined(VMSWAP) 350 351 /* 352 * fetch an anon's page. 353 * 354 * => anon must be locked, and is unlocked upon return. 355 * => returns true if pagein was aborted due to lack of memory. 356 */ 357 358 bool 359 uvm_anon_pagein(struct vm_anon *anon) 360 { 361 struct vm_page *pg; 362 struct uvm_object *uobj; 363 int rv; 364 365 /* locked: anon */ 366 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 367 368 rv = uvmfault_anonget(NULL, NULL, anon); 369 370 /* 371 * if rv == 0, anon is still locked, else anon 372 * is unlocked 373 */ 374 375 switch (rv) { 376 case 0: 377 break; 378 379 case EIO: 380 case ERESTART: 381 382 /* 383 * nothing more to do on errors. 384 * ERESTART can only mean that the anon was freed, 385 * so again there's nothing to do. 386 */ 387 388 return false; 389 390 default: 391 return true; 392 } 393 394 /* 395 * ok, we've got the page now. 396 * mark it as dirty, clear its swslot and un-busy it. 397 */ 398 399 pg = anon->an_page; 400 uobj = pg->uobject; 401 if (anon->an_swslot > 0) 402 uvm_swap_free(anon->an_swslot, 1); 403 anon->an_swslot = 0; 404 pg->flags &= ~(PG_CLEAN); 405 406 /* 407 * deactivate the page (to put it on a page queue) 408 */ 409 410 pmap_clear_reference(pg); 411 uvm_lock_pageq(); 412 if (pg->wire_count == 0) 413 uvm_pagedeactivate(pg); 414 uvm_unlock_pageq(); 415 416 if (pg->flags & PG_WANTED) { 417 wakeup(pg); 418 pg->flags &= ~(PG_WANTED); 419 } 420 421 /* 422 * unlock the anon and we're done. 423 */ 424 425 simple_unlock(&anon->an_lock); 426 if (uobj) { 427 simple_unlock(&uobj->vmobjlock); 428 } 429 return false; 430 } 431 432 #endif /* defined(VMSWAP) */ 433 434 /* 435 * uvm_anon_release: release an anon and its page. 436 * 437 * => caller must lock the anon. 438 */ 439 440 void 441 uvm_anon_release(struct vm_anon *anon) 442 { 443 struct vm_page *pg = anon->an_page; 444 445 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 446 447 KASSERT(pg != NULL); 448 KASSERT((pg->flags & PG_RELEASED) != 0); 449 KASSERT((pg->flags & PG_BUSY) != 0); 450 KASSERT(pg->uobject == NULL); 451 KASSERT(pg->uanon == anon); 452 KASSERT(pg->loan_count == 0); 453 KASSERT(anon->an_ref == 0); 454 455 uvm_lock_pageq(); 456 uvm_pagefree(pg); 457 uvm_unlock_pageq(); 458 simple_unlock(&anon->an_lock); 459 460 KASSERT(anon->an_page == NULL); 461 462 uvm_anfree(anon); 463 } 464