1 /* $NetBSD: uvm_anon.c,v 1.36 2005/07/31 04:04:47 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 1.36 2005/07/31 04:04:47 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 54 static POOL_INIT(uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 0, "anonpl", 55 &pool_allocator_nointr); 56 static struct pool_cache uvm_anon_pool_cache; 57 58 static int uvm_anon_ctor(void *, void *, int); 59 60 /* 61 * allocate anons 62 */ 63 void 64 uvm_anon_init(void) 65 { 66 67 pool_cache_init(&uvm_anon_pool_cache, &uvm_anon_pool, 68 uvm_anon_ctor, NULL, 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 anon->an_swslot = 0; 80 81 return 0; 82 } 83 84 /* 85 * allocate an anon 86 * 87 * => new anon is returned locked! 88 */ 89 struct vm_anon * 90 uvm_analloc(void) 91 { 92 struct vm_anon *anon; 93 94 anon = pool_cache_get(&uvm_anon_pool_cache, PR_NOWAIT); 95 if (anon) { 96 KASSERT(anon->an_ref == 0); 97 LOCK_ASSERT(simple_lock_held(&anon->an_lock) == 0); 98 KASSERT(anon->an_page == NULL); 99 KASSERT(anon->an_swslot == 0); 100 anon->an_ref = 1; 101 simple_lock(&anon->an_lock); 102 } 103 return anon; 104 } 105 106 /* 107 * uvm_anfree: free a single anon structure 108 * 109 * => caller must remove anon from its amap before calling (if it was in 110 * an amap). 111 * => anon must be unlocked and have a zero reference count. 112 * => we may lock the pageq's. 113 */ 114 115 void 116 uvm_anfree(struct vm_anon *anon) 117 { 118 struct vm_page *pg; 119 UVMHIST_FUNC("uvm_anfree"); UVMHIST_CALLED(maphist); 120 UVMHIST_LOG(maphist,"(anon=0x%x)", anon, 0,0,0); 121 122 KASSERT(anon->an_ref == 0); 123 LOCK_ASSERT(!simple_lock_held(&anon->an_lock)); 124 125 /* 126 * get page 127 */ 128 129 pg = anon->an_page; 130 131 /* 132 * if there is a resident page and it is loaned, then anon may not 133 * own it. call out to uvm_anon_lockpage() to ensure the real owner 134 * of the page has been identified and locked. 135 */ 136 137 if (pg && pg->loan_count) { 138 simple_lock(&anon->an_lock); 139 pg = uvm_anon_lockloanpg(anon); 140 simple_unlock(&anon->an_lock); 141 } 142 143 /* 144 * if we have a resident page, we must dispose of it before freeing 145 * the anon. 146 */ 147 148 if (pg) { 149 150 /* 151 * if the page is owned by a uobject (now locked), then we must 152 * kill the loan on the page rather than free it. 153 */ 154 155 if (pg->uobject) { 156 uvm_lock_pageq(); 157 KASSERT(pg->loan_count > 0); 158 pg->loan_count--; 159 pg->uanon = NULL; 160 uvm_unlock_pageq(); 161 simple_unlock(&pg->uobject->vmobjlock); 162 } else { 163 164 /* 165 * page has no uobject, so we must be the owner of it. 166 */ 167 168 KASSERT((pg->flags & PG_RELEASED) == 0); 169 simple_lock(&anon->an_lock); 170 pmap_page_protect(pg, VM_PROT_NONE); 171 172 /* 173 * if the page is busy, mark it as PG_RELEASED 174 * so that uvm_anon_release will release it later. 175 */ 176 177 if (pg->flags & PG_BUSY) { 178 pg->flags |= PG_RELEASED; 179 simple_unlock(&anon->an_lock); 180 return; 181 } 182 uvm_lock_pageq(); 183 uvm_pagefree(pg); 184 uvm_unlock_pageq(); 185 simple_unlock(&anon->an_lock); 186 UVMHIST_LOG(maphist, "anon 0x%x, page 0x%x: " 187 "freed now!", anon, pg, 0, 0); 188 } 189 } 190 if (pg == NULL && anon->an_swslot > 0) { 191 /* this page is no longer only in swap. */ 192 simple_lock(&uvm.swap_data_lock); 193 KASSERT(uvmexp.swpgonly > 0); 194 uvmexp.swpgonly--; 195 simple_unlock(&uvm.swap_data_lock); 196 } 197 198 /* 199 * free any swap resources. 200 */ 201 202 uvm_anon_dropswap(anon); 203 204 /* 205 * now that we've stripped the data areas from the anon, 206 * free the anon itself. 207 */ 208 209 KASSERT(anon->an_page == NULL); 210 KASSERT(anon->an_swslot == 0); 211 212 pool_cache_put(&uvm_anon_pool_cache, anon); 213 UVMHIST_LOG(maphist,"<- done!",0,0,0,0); 214 } 215 216 /* 217 * uvm_anon_dropswap: release any swap resources from this anon. 218 * 219 * => anon must be locked or have a reference count of 0. 220 */ 221 void 222 uvm_anon_dropswap(struct vm_anon *anon) 223 { 224 UVMHIST_FUNC("uvm_anon_dropswap"); UVMHIST_CALLED(maphist); 225 226 if (anon->an_swslot == 0) 227 return; 228 229 UVMHIST_LOG(maphist,"freeing swap for anon %p, paged to swslot 0x%x", 230 anon, anon->an_swslot, 0, 0); 231 uvm_swap_free(anon->an_swslot, 1); 232 anon->an_swslot = 0; 233 } 234 235 /* 236 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 237 * 238 * => anon is locked by caller 239 * => on return: anon is locked 240 * if there is a resident page: 241 * if it has a uobject, it is locked by us 242 * if it is ownerless, we take over as owner 243 * we return the resident page (it can change during 244 * this function) 245 * => note that the only time an anon has an ownerless resident page 246 * is if the page was loaned from a uvm_object and the uvm_object 247 * disowned it 248 * => this only needs to be called when you want to do an operation 249 * on an anon's resident page and that page has a non-zero loan 250 * count. 251 */ 252 struct vm_page * 253 uvm_anon_lockloanpg(struct vm_anon *anon) 254 { 255 struct vm_page *pg; 256 boolean_t locked = FALSE; 257 258 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 259 260 /* 261 * loop while we have a resident page that has a non-zero loan count. 262 * if we successfully get our lock, we will "break" the loop. 263 * note that the test for pg->loan_count is not protected -- this 264 * may produce false positive results. note that a false positive 265 * result may cause us to do more work than we need to, but it will 266 * not produce an incorrect result. 267 */ 268 269 while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) { 270 271 /* 272 * quickly check to see if the page has an object before 273 * bothering to lock the page queues. this may also produce 274 * a false positive result, but that's ok because we do a real 275 * check after that. 276 */ 277 278 if (pg->uobject) { 279 uvm_lock_pageq(); 280 if (pg->uobject) { 281 locked = 282 simple_lock_try(&pg->uobject->vmobjlock); 283 } else { 284 /* object disowned before we got PQ lock */ 285 locked = TRUE; 286 } 287 uvm_unlock_pageq(); 288 289 /* 290 * if we didn't get a lock (try lock failed), then we 291 * toggle our anon lock and try again 292 */ 293 294 if (!locked) { 295 simple_unlock(&anon->an_lock); 296 297 /* 298 * someone locking the object has a chance to 299 * lock us right now 300 */ 301 302 simple_lock(&anon->an_lock); 303 continue; 304 } 305 } 306 307 /* 308 * if page is un-owned [i.e. the object dropped its ownership], 309 * then we can take over as owner! 310 */ 311 312 if (pg->uobject == NULL && (pg->pqflags & PQ_ANON) == 0) { 313 uvm_lock_pageq(); 314 pg->pqflags |= PQ_ANON; 315 pg->loan_count--; 316 uvm_unlock_pageq(); 317 } 318 break; 319 } 320 return(pg); 321 } 322 323 /* 324 * fetch an anon's page. 325 * 326 * => anon must be locked, and is unlocked upon return. 327 * => returns TRUE if pagein was aborted due to lack of memory. 328 */ 329 330 boolean_t 331 uvm_anon_pagein(struct vm_anon *anon) 332 { 333 struct vm_page *pg; 334 struct uvm_object *uobj; 335 int rv; 336 337 /* locked: anon */ 338 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 339 340 rv = uvmfault_anonget(NULL, NULL, anon); 341 342 /* 343 * if rv == 0, anon is still locked, else anon 344 * is unlocked 345 */ 346 347 switch (rv) { 348 case 0: 349 break; 350 351 case EIO: 352 case ERESTART: 353 354 /* 355 * nothing more to do on errors. 356 * ERESTART can only mean that the anon was freed, 357 * so again there's nothing to do. 358 */ 359 360 return FALSE; 361 362 default: 363 return TRUE; 364 } 365 366 /* 367 * ok, we've got the page now. 368 * mark it as dirty, clear its swslot and un-busy it. 369 */ 370 371 pg = anon->an_page; 372 uobj = pg->uobject; 373 if (anon->an_swslot > 0) 374 uvm_swap_free(anon->an_swslot, 1); 375 anon->an_swslot = 0; 376 pg->flags &= ~(PG_CLEAN); 377 378 /* 379 * deactivate the page (to put it on a page queue) 380 */ 381 382 pmap_clear_reference(pg); 383 uvm_lock_pageq(); 384 if (pg->wire_count == 0) 385 uvm_pagedeactivate(pg); 386 uvm_unlock_pageq(); 387 388 if (pg->flags & PG_WANTED) { 389 wakeup(pg); 390 pg->flags &= ~(PG_WANTED); 391 } 392 393 /* 394 * unlock the anon and we're done. 395 */ 396 397 simple_unlock(&anon->an_lock); 398 if (uobj) { 399 simple_unlock(&uobj->vmobjlock); 400 } 401 return FALSE; 402 } 403 404 /* 405 * uvm_anon_release: release an anon and its page. 406 * 407 * => caller must lock the anon. 408 */ 409 410 void 411 uvm_anon_release(struct vm_anon *anon) 412 { 413 struct vm_page *pg = anon->an_page; 414 415 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 416 417 KASSERT(pg != NULL); 418 KASSERT((pg->flags & PG_RELEASED) != 0); 419 KASSERT((pg->flags & PG_BUSY) != 0); 420 KASSERT(pg->uobject == NULL); 421 KASSERT(pg->uanon == anon); 422 KASSERT(pg->loan_count == 0); 423 KASSERT(anon->an_ref == 0); 424 425 uvm_lock_pageq(); 426 uvm_pagefree(pg); 427 uvm_unlock_pageq(); 428 simple_unlock(&anon->an_lock); 429 430 KASSERT(anon->an_page == NULL); 431 432 uvm_anfree(anon); 433 } 434