1 /* $NetBSD: uvm_anon.c,v 1.40 2006/10/12 01:32:52 christos 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 1.40 2006/10/12 01:32:52 christos 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); 57 static struct pool_cache uvm_anon_pool_cache; 58 59 static int uvm_anon_ctor(void *, void *, int); 60 61 /* 62 * allocate anons 63 */ 64 void 65 uvm_anon_init(void) 66 { 67 68 pool_cache_init(&uvm_anon_pool_cache, &uvm_anon_pool, 69 uvm_anon_ctor, NULL, NULL); 70 } 71 72 static int 73 uvm_anon_ctor(void *arg __unused, void *object, int flags __unused) 74 { 75 struct vm_anon *anon = object; 76 77 anon->an_ref = 0; 78 simple_lock_init(&anon->an_lock); 79 anon->an_page = NULL; 80 #if defined(VMSWAP) 81 anon->an_swslot = 0; 82 #endif /* defined(VMSWAP) */ 83 84 return 0; 85 } 86 87 /* 88 * allocate an anon 89 * 90 * => new anon is returned locked! 91 */ 92 struct vm_anon * 93 uvm_analloc(void) 94 { 95 struct vm_anon *anon; 96 97 anon = pool_cache_get(&uvm_anon_pool_cache, PR_NOWAIT); 98 if (anon) { 99 KASSERT(anon->an_ref == 0); 100 LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); 101 KASSERT(anon->an_page == NULL); 102 #if defined(VMSWAP) 103 KASSERT(anon->an_swslot == 0); 104 #endif /* defined(VMSWAP) */ 105 anon->an_ref = 1; 106 simple_lock(&anon->an_lock); 107 } 108 return anon; 109 } 110 111 /* 112 * uvm_anfree: free a single anon structure 113 * 114 * => caller must remove anon from its amap before calling (if it was in 115 * an amap). 116 * => anon must be unlocked and have a zero reference count. 117 * => we may lock the pageq's. 118 */ 119 120 void 121 uvm_anfree(struct vm_anon *anon) 122 { 123 struct vm_page *pg; 124 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 125 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 126 127 KASSERT(anon->an_ref == 0); 128 LOCK_ASSERT(!simple_lock_held(&anon->an_lock)); 129 130 /* 131 * get page 132 */ 133 134 pg = anon->an_page; 135 136 /* 137 * if there is a resident page and it is loaned, then anon may not 138 * own it. call out to uvm_anon_lockpage() to ensure the real owner 139 * of the page has been identified and locked. 140 */ 141 142 if (pg && pg->loan_count) { 143 simple_lock(&anon->an_lock); 144 pg = uvm_anon_lockloanpg(anon); 145 simple_unlock(&anon->an_lock); 146 } 147 148 /* 149 * if we have a resident page, we must dispose of it before freeing 150 * the anon. 151 */ 152 153 if (pg) { 154 155 /* 156 * if the page is owned by a uobject (now locked), then we must 157 * kill the loan on the page rather than free it. 158 */ 159 160 if (pg->uobject) { 161 uvm_lock_pageq(); 162 KASSERT(pg->loan_count > 0); 163 pg->loan_count--; 164 pg->uanon = NULL; 165 uvm_unlock_pageq(); 166 simple_unlock(&pg->uobject->vmobjlock); 167 } else { 168 169 /* 170 * page has no uobject, so we must be the owner of it. 171 */ 172 173 KASSERT((pg->flags & PG_RELEASED) == 0); 174 simple_lock(&anon->an_lock); 175 pmap_page_protect(pg, VM_PROT_NONE); 176 177 /* 178 * if the page is busy, mark it as PG_RELEASED 179 * so that uvm_anon_release will release it later. 180 */ 181 182 if (pg->flags & PG_BUSY) { 183 pg->flags |= PG_RELEASED; 184 simple_unlock(&anon->an_lock); 185 return; 186 } 187 uvm_lock_pageq(); 188 uvm_pagefree(pg); 189 uvm_unlock_pageq(); 190 simple_unlock(&anon->an_lock); 191 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 192 "freed now!", anon, pg, 0, 0); 193 } 194 } 195 #if defined(VMSWAP) 196 if (pg == NULL && anon->an_swslot > 0) { 197 /* this page is no longer only in swap. */ 198 simple_lock(&uvm.swap_data_lock); 199 KASSERT(uvmexp.swpgonly > 0); 200 uvmexp.swpgonly--; 201 simple_unlock(&uvm.swap_data_lock); 202 } 203 #endif /* defined(VMSWAP) */ 204 205 /* 206 * free any swap resources. 207 */ 208 209 uvm_anon_dropswap(anon); 210 211 /* 212 * give a page replacement hint. 213 */ 214 215 uvmpdpol_anfree(anon); 216 217 /* 218 * now that we've stripped the data areas from the anon, 219 * free the anon itself. 220 */ 221 222 KASSERT(anon->an_page == NULL); 223 #if defined(VMSWAP) 224 KASSERT(anon->an_swslot == 0); 225 #endif /* defined(VMSWAP) */ 226 227 pool_cache_put(&uvm_anon_pool_cache, anon); 228 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 229 } 230 231 #if defined(VMSWAP) 232 233 /* 234 * uvm_anon_dropswap: release any swap resources from this anon. 235 * 236 * => anon must be locked or have a reference count of 0. 237 */ 238 void 239 uvm_anon_dropswap(struct vm_anon *anon) 240 { 241 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 242 243 if (anon->an_swslot == 0) 244 return; 245 246 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 247 anon, anon->an_swslot, 0, 0); 248 uvm_swap_free(anon->an_swslot, 1); 249 anon->an_swslot = 0; 250 } 251 252 #endif /* defined(VMSWAP) */ 253 254 /* 255 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 256 * 257 * => anon is locked by caller 258 * => on return: anon is locked 259 * if there is a resident page: 260 * if it has a uobject, it is locked by us 261 * if it is ownerless, we take over as owner 262 * we return the resident page (it can change during 263 * this function) 264 * => note that the only time an anon has an ownerless resident page 265 * is if the page was loaned from a uvm_object and the uvm_object 266 * disowned it 267 * => this only needs to be called when you want to do an operation 268 * on an anon's resident page and that page has a non-zero loan 269 * count. 270 */ 271 struct vm_page * 272 uvm_anon_lockloanpg(struct vm_anon *anon) 273 { 274 struct vm_page *pg; 275 boolean_t locked = FALSE; 276 277 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 278 279 /* 280 * loop while we have a resident page that has a non-zero loan count. 281 * if we successfully get our lock, we will "break" the loop. 282 * note that the test for pg->loan_count is not protected -- this 283 * may produce false positive results. note that a false positive 284 * result may cause us to do more work than we need to, but it will 285 * not produce an incorrect result. 286 */ 287 288 while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) { 289 290 /* 291 * quickly check to see if the page has an object before 292 * bothering to lock the page queues. this may also produce 293 * a false positive result, but that's ok because we do a real 294 * check after that. 295 */ 296 297 if (pg->uobject) { 298 uvm_lock_pageq(); 299 if (pg->uobject) { 300 locked = 301 simple_lock_try(&pg->uobject->vmobjlock); 302 } else { 303 /* object disowned before we got PQ lock */ 304 locked = TRUE; 305 } 306 uvm_unlock_pageq(); 307 308 /* 309 * if we didn't get a lock (try lock failed), then we 310 * toggle our anon lock and try again 311 */ 312 313 if (!locked) { 314 simple_unlock(&anon->an_lock); 315 316 /* 317 * someone locking the object has a chance to 318 * lock us right now 319 */ 320 321 simple_lock(&anon->an_lock); 322 continue; 323 } 324 } 325 326 /* 327 * if page is un-owned [i.e. the object dropped its ownership], 328 * then we can take over as owner! 329 */ 330 331 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 332 uvm_lock_pageq(); 333 pg->pqflags |= PQ_ANON; 334 pg->loan_count--; 335 uvm_unlock_pageq(); 336 } 337 break; 338 } 339 return(pg); 340 } 341 342 #if defined(VMSWAP) 343 344 /* 345 * fetch an anon's page. 346 * 347 * => anon must be locked, and is unlocked upon return. 348 * => returns TRUE if pagein was aborted due to lack of memory. 349 */ 350 351 boolean_t 352 uvm_anon_pagein(struct vm_anon *anon) 353 { 354 struct vm_page *pg; 355 struct uvm_object *uobj; 356 int rv; 357 358 /* locked: anon */ 359 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 360 361 rv = uvmfault_anonget(NULL, NULL, anon); 362 363 /* 364 * if rv == 0, anon is still locked, else anon 365 * is unlocked 366 */ 367 368 switch (rv) { 369 case 0: 370 break; 371 372 case EIO: 373 case ERESTART: 374 375 /* 376 * nothing more to do on errors. 377 * ERESTART can only mean that the anon was freed, 378 * so again there's nothing to do. 379 */ 380 381 return FALSE; 382 383 default: 384 return TRUE; 385 } 386 387 /* 388 * ok, we've got the page now. 389 * mark it as dirty, clear its swslot and un-busy it. 390 */ 391 392 pg = anon->an_page; 393 uobj = pg->uobject; 394 if (anon->an_swslot > 0) 395 uvm_swap_free(anon->an_swslot, 1); 396 anon->an_swslot = 0; 397 pg->flags &= ~(PG_CLEAN); 398 399 /* 400 * deactivate the page (to put it on a page queue) 401 */ 402 403 pmap_clear_reference(pg); 404 uvm_lock_pageq(); 405 if (pg->wire_count == 0) 406 uvm_pagedeactivate(pg); 407 uvm_unlock_pageq(); 408 409 if (pg->flags & PG_WANTED) { 410 wakeup(pg); 411 pg->flags &= ~(PG_WANTED); 412 } 413 414 /* 415 * unlock the anon and we're done. 416 */ 417 418 simple_unlock(&anon->an_lock); 419 if (uobj) { 420 simple_unlock(&uobj->vmobjlock); 421 } 422 return FALSE; 423 } 424 425 #endif /* defined(VMSWAP) */ 426 427 /* 428 * uvm_anon_release: release an anon and its page. 429 * 430 * => caller must lock the anon. 431 */ 432 433 void 434 uvm_anon_release(struct vm_anon *anon) 435 { 436 struct vm_page *pg = anon->an_page; 437 438 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 439 440 KASSERT(pg != NULL); 441 KASSERT((pg->flags & PG_RELEASED) != 0); 442 KASSERT((pg->flags & PG_BUSY) != 0); 443 KASSERT(pg->uobject == NULL); 444 KASSERT(pg->uanon == anon); 445 KASSERT(pg->loan_count == 0); 446 KASSERT(anon->an_ref == 0); 447 448 uvm_lock_pageq(); 449 uvm_pagefree(pg); 450 uvm_unlock_pageq(); 451 simple_unlock(&anon->an_lock); 452 453 KASSERT(anon->an_page == NULL); 454 455 uvm_anfree(anon); 456 } 457