1 /* $OpenBSD: uvm_aobj.c,v 1.36 2009/03/20 15:19:04 oga Exp $ */ 2 /* $NetBSD: uvm_aobj.c,v 1.39 2001/02/18 21:19:08 chs Exp $ */ 3 4 /* 5 * Copyright (c) 1998 Chuck Silvers, Charles D. Cranor and 6 * Washington University. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by Charles D. Cranor and 20 * Washington University. 21 * 4. The name of the author may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 * 35 * from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp 36 */ 37 /* 38 * uvm_aobj.c: anonymous memory uvm_object pager 39 * 40 * author: Chuck Silvers <chuq@chuq.com> 41 * started: Jan-1998 42 * 43 * - design mostly from Chuck Cranor 44 */ 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/proc.h> 49 #include <sys/malloc.h> 50 #include <sys/kernel.h> 51 #include <sys/pool.h> 52 #include <sys/kernel.h> 53 54 #include <uvm/uvm.h> 55 56 /* 57 * an aobj manages anonymous-memory backed uvm_objects. in addition 58 * to keeping the list of resident pages, it also keeps a list of 59 * allocated swap blocks. depending on the size of the aobj this list 60 * of allocated swap blocks is either stored in an array (small objects) 61 * or in a hash table (large objects). 62 */ 63 64 /* 65 * local structures 66 */ 67 68 /* 69 * for hash tables, we break the address space of the aobj into blocks 70 * of UAO_SWHASH_CLUSTER_SIZE pages. we require the cluster size to 71 * be a power of two. 72 */ 73 74 #define UAO_SWHASH_CLUSTER_SHIFT 4 75 #define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT) 76 77 /* get the "tag" for this page index */ 78 #define UAO_SWHASH_ELT_TAG(PAGEIDX) \ 79 ((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) 80 81 /* given an ELT and a page index, find the swap slot */ 82 #define UAO_SWHASH_ELT_PAGESLOT(ELT, PAGEIDX) \ 83 ((ELT)->slots[(PAGEIDX) & (UAO_SWHASH_CLUSTER_SIZE - 1)]) 84 85 /* given an ELT, return its pageidx base */ 86 #define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \ 87 ((ELT)->tag << UAO_SWHASH_CLUSTER_SHIFT) 88 89 /* 90 * the swhash hash function 91 */ 92 #define UAO_SWHASH_HASH(AOBJ, PAGEIDX) \ 93 (&(AOBJ)->u_swhash[(((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) \ 94 & (AOBJ)->u_swhashmask)]) 95 96 /* 97 * the swhash threshold determines if we will use an array or a 98 * hash table to store the list of allocated swap blocks. 99 */ 100 101 #define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4) 102 #define UAO_USES_SWHASH(AOBJ) \ 103 ((AOBJ)->u_pages > UAO_SWHASH_THRESHOLD) /* use hash? */ 104 105 /* 106 * the number of buckets in a swhash, with an upper bound 107 */ 108 #define UAO_SWHASH_MAXBUCKETS 256 109 #define UAO_SWHASH_BUCKETS(AOBJ) \ 110 (min((AOBJ)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, \ 111 UAO_SWHASH_MAXBUCKETS)) 112 113 114 /* 115 * uao_swhash_elt: when a hash table is being used, this structure defines 116 * the format of an entry in the bucket list. 117 */ 118 119 struct uao_swhash_elt { 120 LIST_ENTRY(uao_swhash_elt) list; /* the hash list */ 121 voff_t tag; /* our 'tag' */ 122 int count; /* our number of active slots */ 123 int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */ 124 }; 125 126 /* 127 * uao_swhash: the swap hash table structure 128 */ 129 130 LIST_HEAD(uao_swhash, uao_swhash_elt); 131 132 /* 133 * uao_swhash_elt_pool: pool of uao_swhash_elt structures 134 */ 135 136 struct pool uao_swhash_elt_pool; 137 138 /* 139 * uvm_aobj: the actual anon-backed uvm_object 140 * 141 * => the uvm_object is at the top of the structure, this allows 142 * (struct uvm_device *) == (struct uvm_object *) 143 * => only one of u_swslots and u_swhash is used in any given aobj 144 */ 145 146 struct uvm_aobj { 147 struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */ 148 int u_pages; /* number of pages in entire object */ 149 int u_flags; /* the flags (see uvm_aobj.h) */ 150 int *u_swslots; /* array of offset->swapslot mappings */ 151 /* 152 * hashtable of offset->swapslot mappings 153 * (u_swhash is an array of bucket heads) 154 */ 155 struct uao_swhash *u_swhash; 156 u_long u_swhashmask; /* mask for hashtable */ 157 LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */ 158 }; 159 160 /* 161 * uvm_aobj_pool: pool of uvm_aobj structures 162 */ 163 164 struct pool uvm_aobj_pool; 165 166 /* 167 * local functions 168 */ 169 170 static struct uao_swhash_elt *uao_find_swhash_elt(struct uvm_aobj *, int, 171 boolean_t); 172 static int uao_find_swslot(struct uvm_aobj *, int); 173 static boolean_t uao_flush(struct uvm_object *, voff_t, 174 voff_t, int); 175 static void uao_free(struct uvm_aobj *); 176 static int uao_get(struct uvm_object *, voff_t, 177 vm_page_t *, int *, int, vm_prot_t, 178 int, int); 179 static boolean_t uao_releasepg(struct vm_page *, 180 struct vm_page **); 181 static boolean_t uao_pagein(struct uvm_aobj *, int, int); 182 static boolean_t uao_pagein_page(struct uvm_aobj *, int); 183 184 /* 185 * aobj_pager 186 * 187 * note that some functions (e.g. put) are handled elsewhere 188 */ 189 190 struct uvm_pagerops aobj_pager = { 191 NULL, /* init */ 192 uao_reference, /* reference */ 193 uao_detach, /* detach */ 194 NULL, /* fault */ 195 uao_flush, /* flush */ 196 uao_get, /* get */ 197 NULL, /* put (done by pagedaemon) */ 198 NULL, /* cluster */ 199 NULL, /* mk_pcluster */ 200 uao_releasepg /* releasepg */ 201 }; 202 203 /* 204 * uao_list: global list of active aobjs, locked by uao_list_lock 205 */ 206 207 static LIST_HEAD(aobjlist, uvm_aobj) uao_list; 208 static simple_lock_data_t uao_list_lock; 209 210 211 /* 212 * functions 213 */ 214 215 /* 216 * hash table/array related functions 217 */ 218 219 /* 220 * uao_find_swhash_elt: find (or create) a hash table entry for a page 221 * offset. 222 * 223 * => the object should be locked by the caller 224 */ 225 226 static struct uao_swhash_elt * 227 uao_find_swhash_elt(struct uvm_aobj *aobj, int pageidx, boolean_t create) 228 { 229 struct uao_swhash *swhash; 230 struct uao_swhash_elt *elt; 231 voff_t page_tag; 232 233 swhash = UAO_SWHASH_HASH(aobj, pageidx); /* first hash to get bucket */ 234 page_tag = UAO_SWHASH_ELT_TAG(pageidx); /* tag to search for */ 235 236 /* 237 * now search the bucket for the requested tag 238 */ 239 LIST_FOREACH(elt, swhash, list) { 240 if (elt->tag == page_tag) 241 return(elt); 242 } 243 244 /* fail now if we are not allowed to create a new entry in the bucket */ 245 if (!create) 246 return NULL; 247 248 249 /* 250 * allocate a new entry for the bucket and init/insert it in 251 */ 252 elt = pool_get(&uao_swhash_elt_pool, PR_WAITOK); 253 LIST_INSERT_HEAD(swhash, elt, list); 254 elt->tag = page_tag; 255 elt->count = 0; 256 memset(elt->slots, 0, sizeof(elt->slots)); 257 258 return(elt); 259 } 260 261 /* 262 * uao_find_swslot: find the swap slot number for an aobj/pageidx 263 * 264 * => object must be locked by caller 265 */ 266 __inline static int 267 uao_find_swslot(struct uvm_aobj *aobj, int pageidx) 268 { 269 270 /* 271 * if noswap flag is set, then we never return a slot 272 */ 273 274 if (aobj->u_flags & UAO_FLAG_NOSWAP) 275 return(0); 276 277 /* 278 * if hashing, look in hash table. 279 */ 280 281 if (UAO_USES_SWHASH(aobj)) { 282 struct uao_swhash_elt *elt = 283 uao_find_swhash_elt(aobj, pageidx, FALSE); 284 285 if (elt) 286 return(UAO_SWHASH_ELT_PAGESLOT(elt, pageidx)); 287 else 288 return(0); 289 } 290 291 /* 292 * otherwise, look in the array 293 */ 294 return(aobj->u_swslots[pageidx]); 295 } 296 297 /* 298 * uao_set_swslot: set the swap slot for a page in an aobj. 299 * 300 * => setting a slot to zero frees the slot 301 * => object must be locked by caller 302 */ 303 int 304 uao_set_swslot(struct uvm_object *uobj, int pageidx, int slot) 305 { 306 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 307 int oldslot; 308 UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist); 309 UVMHIST_LOG(pdhist, "aobj %p pageidx %ld slot %ld", 310 aobj, pageidx, slot, 0); 311 312 /* 313 * if noswap flag is set, then we can't set a slot 314 */ 315 316 if (aobj->u_flags & UAO_FLAG_NOSWAP) { 317 318 if (slot == 0) 319 return(0); /* a clear is ok */ 320 321 /* but a set is not */ 322 printf("uao_set_swslot: uobj = %p\n", uobj); 323 panic("uao_set_swslot: attempt to set a slot on a NOSWAP object"); 324 } 325 326 /* 327 * are we using a hash table? if so, add it in the hash. 328 */ 329 330 if (UAO_USES_SWHASH(aobj)) { 331 332 /* 333 * Avoid allocating an entry just to free it again if 334 * the page had not swap slot in the first place, and 335 * we are freeing. 336 */ 337 338 struct uao_swhash_elt *elt = 339 uao_find_swhash_elt(aobj, pageidx, slot ? TRUE : FALSE); 340 if (elt == NULL) { 341 KASSERT(slot == 0); 342 return (0); 343 } 344 345 oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx); 346 UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot; 347 348 /* 349 * now adjust the elt's reference counter and free it if we've 350 * dropped it to zero. 351 */ 352 353 /* an allocation? */ 354 if (slot) { 355 if (oldslot == 0) 356 elt->count++; 357 } else { /* freeing slot ... */ 358 if (oldslot) /* to be safe */ 359 elt->count--; 360 361 if (elt->count == 0) { 362 LIST_REMOVE(elt, list); 363 pool_put(&uao_swhash_elt_pool, elt); 364 } 365 } 366 } else { 367 /* we are using an array */ 368 oldslot = aobj->u_swslots[pageidx]; 369 aobj->u_swslots[pageidx] = slot; 370 } 371 return (oldslot); 372 } 373 374 /* 375 * end of hash/array functions 376 */ 377 378 /* 379 * uao_free: free all resources held by an aobj, and then free the aobj 380 * 381 * => the aobj should be dead 382 */ 383 static void 384 uao_free(struct uvm_aobj *aobj) 385 { 386 387 simple_unlock(&aobj->u_obj.vmobjlock); 388 389 if (UAO_USES_SWHASH(aobj)) { 390 int i, hashbuckets = aobj->u_swhashmask + 1; 391 392 /* 393 * free the swslots from each hash bucket, 394 * then the hash bucket, and finally the hash table itself. 395 */ 396 for (i = 0; i < hashbuckets; i++) { 397 struct uao_swhash_elt *elt, *next; 398 399 for (elt = LIST_FIRST(&aobj->u_swhash[i]); 400 elt != NULL; 401 elt = next) { 402 int j; 403 404 for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++) { 405 int slot = elt->slots[j]; 406 407 if (slot == 0) { 408 continue; 409 } 410 uvm_swap_free(slot, 1); 411 412 /* 413 * this page is no longer 414 * only in swap. 415 */ 416 simple_lock(&uvm.swap_data_lock); 417 uvmexp.swpgonly--; 418 simple_unlock(&uvm.swap_data_lock); 419 } 420 421 next = LIST_NEXT(elt, list); 422 pool_put(&uao_swhash_elt_pool, elt); 423 } 424 } 425 free(aobj->u_swhash, M_UVMAOBJ); 426 } else { 427 int i; 428 429 /* 430 * free the array 431 */ 432 433 for (i = 0; i < aobj->u_pages; i++) { 434 int slot = aobj->u_swslots[i]; 435 436 if (slot) { 437 uvm_swap_free(slot, 1); 438 439 /* this page is no longer only in swap. */ 440 simple_lock(&uvm.swap_data_lock); 441 uvmexp.swpgonly--; 442 simple_unlock(&uvm.swap_data_lock); 443 } 444 } 445 free(aobj->u_swslots, M_UVMAOBJ); 446 } 447 448 /* 449 * finally free the aobj itself 450 */ 451 pool_put(&uvm_aobj_pool, aobj); 452 } 453 454 /* 455 * pager functions 456 */ 457 458 /* 459 * uao_create: create an aobj of the given size and return its uvm_object. 460 * 461 * => for normal use, flags are always zero 462 * => for the kernel object, the flags are: 463 * UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once) 464 * UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ") 465 */ 466 struct uvm_object * 467 uao_create(vsize_t size, int flags) 468 { 469 static struct uvm_aobj kernel_object_store; /* home of kernel_object */ 470 static int kobj_alloced = 0; /* not allocated yet */ 471 int pages = round_page(size) >> PAGE_SHIFT; 472 struct uvm_aobj *aobj; 473 474 /* 475 * malloc a new aobj unless we are asked for the kernel object 476 */ 477 if (flags & UAO_FLAG_KERNOBJ) { /* want kernel object? */ 478 if (kobj_alloced) 479 panic("uao_create: kernel object already allocated"); 480 481 aobj = &kernel_object_store; 482 aobj->u_pages = pages; 483 aobj->u_flags = UAO_FLAG_NOSWAP; /* no swap to start */ 484 /* we are special, we never die */ 485 aobj->u_obj.uo_refs = UVM_OBJ_KERN; 486 kobj_alloced = UAO_FLAG_KERNOBJ; 487 } else if (flags & UAO_FLAG_KERNSWAP) { 488 aobj = &kernel_object_store; 489 if (kobj_alloced != UAO_FLAG_KERNOBJ) 490 panic("uao_create: asked to enable swap on kernel object"); 491 kobj_alloced = UAO_FLAG_KERNSWAP; 492 } else { /* normal object */ 493 aobj = pool_get(&uvm_aobj_pool, PR_WAITOK); 494 aobj->u_pages = pages; 495 aobj->u_flags = 0; /* normal object */ 496 aobj->u_obj.uo_refs = 1; /* start with 1 reference */ 497 } 498 499 /* 500 * allocate hash/array if necessary 501 * 502 * note: in the KERNSWAP case no need to worry about locking since 503 * we are still booting we should be the only thread around. 504 */ 505 if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) { 506 int mflags = (flags & UAO_FLAG_KERNSWAP) != 0 ? 507 M_NOWAIT : M_WAITOK; 508 509 /* allocate hash table or array depending on object size */ 510 if (UAO_USES_SWHASH(aobj)) { 511 aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj), 512 M_UVMAOBJ, mflags, &aobj->u_swhashmask); 513 if (aobj->u_swhash == NULL) 514 panic("uao_create: hashinit swhash failed"); 515 } else { 516 aobj->u_swslots = malloc(pages * sizeof(int), 517 M_UVMAOBJ, mflags|M_ZERO); 518 if (aobj->u_swslots == NULL) 519 panic("uao_create: malloc swslots failed"); 520 } 521 522 if (flags) { 523 aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */ 524 return(&aobj->u_obj); 525 /* done! */ 526 } 527 } 528 529 /* 530 * init aobj fields 531 */ 532 simple_lock_init(&aobj->u_obj.vmobjlock); 533 aobj->u_obj.pgops = &aobj_pager; 534 TAILQ_INIT(&aobj->u_obj.memq); 535 aobj->u_obj.uo_npages = 0; 536 537 /* 538 * now that aobj is ready, add it to the global list 539 */ 540 simple_lock(&uao_list_lock); 541 LIST_INSERT_HEAD(&uao_list, aobj, u_list); 542 simple_unlock(&uao_list_lock); 543 544 /* 545 * done! 546 */ 547 return(&aobj->u_obj); 548 } 549 550 551 552 /* 553 * uao_init: set up aobj pager subsystem 554 * 555 * => called at boot time from uvm_pager_init() 556 */ 557 void 558 uao_init(void) 559 { 560 static int uao_initialized; 561 562 if (uao_initialized) 563 return; 564 uao_initialized = TRUE; 565 566 LIST_INIT(&uao_list); 567 simple_lock_init(&uao_list_lock); 568 569 /* 570 * NOTE: Pages fror this pool must not come from a pageable 571 * kernel map! 572 */ 573 pool_init(&uao_swhash_elt_pool, sizeof(struct uao_swhash_elt), 574 0, 0, 0, "uaoeltpl", &pool_allocator_nointr); 575 576 pool_init(&uvm_aobj_pool, sizeof(struct uvm_aobj), 0, 0, 0, 577 "aobjpl", &pool_allocator_nointr); 578 } 579 580 /* 581 * uao_reference: add a ref to an aobj 582 * 583 * => aobj must be unlocked 584 * => just lock it and call the locked version 585 */ 586 void 587 uao_reference(struct uvm_object *uobj) 588 { 589 simple_lock(&uobj->vmobjlock); 590 uao_reference_locked(uobj); 591 simple_unlock(&uobj->vmobjlock); 592 } 593 594 /* 595 * uao_reference_locked: add a ref to an aobj that is already locked 596 * 597 * => aobj must be locked 598 * this needs to be separate from the normal routine 599 * since sometimes we need to add a reference to an aobj when 600 * it's already locked. 601 */ 602 void 603 uao_reference_locked(struct uvm_object *uobj) 604 { 605 UVMHIST_FUNC("uao_reference"); UVMHIST_CALLED(maphist); 606 607 /* 608 * kernel_object already has plenty of references, leave it alone. 609 */ 610 611 if (UVM_OBJ_IS_KERN_OBJECT(uobj)) 612 return; 613 614 uobj->uo_refs++; /* bump! */ 615 UVMHIST_LOG(maphist, "<- done (uobj=%p, ref = %ld)", 616 uobj, uobj->uo_refs,0,0); 617 } 618 619 620 /* 621 * uao_detach: drop a reference to an aobj 622 * 623 * => aobj must be unlocked 624 * => just lock it and call the locked version 625 */ 626 void 627 uao_detach(struct uvm_object *uobj) 628 { 629 simple_lock(&uobj->vmobjlock); 630 uao_detach_locked(uobj); 631 } 632 633 634 /* 635 * uao_detach_locked: drop a reference to an aobj 636 * 637 * => aobj must be locked, and is unlocked (or freed) upon return. 638 * this needs to be separate from the normal routine 639 * since sometimes we need to detach from an aobj when 640 * it's already locked. 641 */ 642 void 643 uao_detach_locked(struct uvm_object *uobj) 644 { 645 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 646 struct vm_page *pg, *next; 647 boolean_t busybody; 648 UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist); 649 650 /* 651 * detaching from kernel_object is a noop. 652 */ 653 if (UVM_OBJ_IS_KERN_OBJECT(uobj)) { 654 simple_unlock(&uobj->vmobjlock); 655 return; 656 } 657 658 UVMHIST_LOG(maphist," (uobj=%p) ref=%ld", uobj,uobj->uo_refs,0,0); 659 uobj->uo_refs--; /* drop ref! */ 660 if (uobj->uo_refs) { /* still more refs? */ 661 simple_unlock(&uobj->vmobjlock); 662 UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0); 663 return; 664 } 665 666 /* 667 * remove the aobj from the global list. 668 */ 669 simple_lock(&uao_list_lock); 670 LIST_REMOVE(aobj, u_list); 671 simple_unlock(&uao_list_lock); 672 673 /* 674 * free all the pages that aren't PG_BUSY, 675 * mark for release any that are. 676 */ 677 busybody = FALSE; 678 for (pg = TAILQ_FIRST(&uobj->memq); pg != NULL; pg = next) { 679 next = TAILQ_NEXT(pg, listq); 680 if (pg->pg_flags & PG_BUSY) { 681 atomic_setbits_int(&pg->pg_flags, PG_RELEASED); 682 busybody = TRUE; 683 continue; 684 } 685 686 /* zap the mappings, free the swap slot, free the page */ 687 pmap_page_protect(pg, VM_PROT_NONE); 688 uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT); 689 uvm_lock_pageq(); 690 uvm_pagefree(pg); 691 uvm_unlock_pageq(); 692 } 693 694 /* 695 * if we found any busy pages, we're done for now. 696 * mark the aobj for death, releasepg will finish up for us. 697 */ 698 if (busybody) { 699 aobj->u_flags |= UAO_FLAG_KILLME; 700 simple_unlock(&aobj->u_obj.vmobjlock); 701 return; 702 } 703 704 /* 705 * finally, free the rest. 706 */ 707 uao_free(aobj); 708 } 709 710 /* 711 * uao_flush: "flush" pages out of a uvm object 712 * 713 * => object should be locked by caller. we may _unlock_ the object 714 * if (and only if) we need to clean a page (PGO_CLEANIT). 715 * XXXJRT Currently, however, we don't. In the case of cleaning 716 * XXXJRT a page, we simply just deactivate it. Should probably 717 * XXXJRT handle this better, in the future (although "flushing" 718 * XXXJRT anonymous memory isn't terribly important). 719 * => if PGO_CLEANIT is not set, then we will neither unlock the object 720 * or block. 721 * => if PGO_ALLPAGE is set, then all pages in the object are valid targets 722 * for flushing. 723 * => NOTE: we rely on the fact that the object's memq is a TAILQ and 724 * that new pages are inserted on the tail end of the list. thus, 725 * we can make a complete pass through the object in one go by starting 726 * at the head and working towards the tail (new pages are put in 727 * front of us). 728 * => NOTE: we are allowed to lock the page queues, so the caller 729 * must not be holding the lock on them [e.g. pagedaemon had 730 * better not call us with the queues locked] 731 * => we return TRUE unless we encountered some sort of I/O error 732 * XXXJRT currently never happens, as we never directly initiate 733 * XXXJRT I/O 734 * 735 * comment on "cleaning" object and PG_BUSY pages: 736 * this routine is holding the lock on the object. the only time 737 * that is can run into a PG_BUSY page that it does not own is if 738 * some other process has started I/O on the page (e.g. either 739 * a pagein or a pageout). if the PG_BUSY page is being paged 740 * in, then it can not be dirty (!PG_CLEAN) because no one has 741 * had a change to modify it yet. if the PG_BUSY page is being 742 * paged out then it means that someone else has already started 743 * cleaning the page for us (how nice!). in this case, if we 744 * have syncio specified, then after we make our pass through the 745 * object we need to wait for the other PG_BUSY pages to clear 746 * off (i.e. we need to do an iosync). also note that once a 747 * page is PG_BUSY is must stary in its object until it is un-busyed. 748 * XXXJRT We never actually do this, as we are "flushing" anonymous 749 * XXXJRT memory, which doesn't have persistent backing store. 750 * 751 * note on page traversal: 752 * we can traverse the pages in an object either by going down the 753 * linked list in "uobj->memq", or we can go over the address range 754 * by page doing hash table lookups for each address. depending 755 * on how many pages are in the object it may be cheaper to do one 756 * or the other. we set "by_list" to true if we are using memq. 757 * if the cost of a hash lookup was equal to the cost of the list 758 * traversal we could compare the number of pages in the start->stop 759 * range to the total number of pages in the object. however, it 760 * seems that a hash table lookup is more expensive than the linked 761 * list traversal, so we multiply the number of pages in the 762 * start->stop range by a penalty which we define below. 763 */ 764 765 #define UAO_HASH_PENALTY 4 /* XXX: a guess */ 766 767 boolean_t 768 uao_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) 769 { 770 struct uvm_aobj *aobj = (struct uvm_aobj *) uobj; 771 struct vm_page *pp, *ppnext; 772 boolean_t retval, by_list; 773 voff_t curoff; 774 UVMHIST_FUNC("uao_flush"); UVMHIST_CALLED(maphist); 775 776 curoff = 0; /* XXX: shut up gcc */ 777 778 retval = TRUE; /* default to success */ 779 780 if (flags & PGO_ALLPAGES) { 781 start = 0; 782 stop = aobj->u_pages << PAGE_SHIFT; 783 by_list = TRUE; /* always go by the list */ 784 } else { 785 start = trunc_page(start); 786 stop = round_page(stop); 787 if (stop > (aobj->u_pages << PAGE_SHIFT)) { 788 printf("uao_flush: strange, got an out of range " 789 "flush (fixed)\n"); 790 stop = aobj->u_pages << PAGE_SHIFT; 791 } 792 by_list = (uobj->uo_npages <= 793 ((stop - start) >> PAGE_SHIFT) * UAO_HASH_PENALTY); 794 } 795 796 UVMHIST_LOG(maphist, 797 " flush start=0x%lx, stop=0x%lx, by_list=%ld, flags=0x%lx", 798 (u_long)start, (u_long)stop, by_list, flags); 799 800 /* 801 * Don't need to do any work here if we're not freeing 802 * or deactivating pages. 803 */ 804 if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) { 805 UVMHIST_LOG(maphist, 806 "<- done (no work to do)",0,0,0,0); 807 return (retval); 808 } 809 810 /* 811 * now do it. note: we must update ppnext in the body of loop or we 812 * will get stuck. we need to use ppnext because we may free "pp" 813 * before doing the next loop. 814 */ 815 816 if (by_list) { 817 pp = TAILQ_FIRST(&uobj->memq); 818 } else { 819 curoff = start; 820 pp = uvm_pagelookup(uobj, curoff); 821 } 822 823 ppnext = NULL; /* XXX: shut up gcc */ 824 uvm_lock_pageq(); /* page queues locked */ 825 826 /* locked: both page queues and uobj */ 827 for ( ; (by_list && pp != NULL) || 828 (!by_list && curoff < stop) ; pp = ppnext) { 829 if (by_list) { 830 ppnext = TAILQ_NEXT(pp, listq); 831 832 /* range check */ 833 if (pp->offset < start || pp->offset >= stop) 834 continue; 835 } else { 836 curoff += PAGE_SIZE; 837 if (curoff < stop) 838 ppnext = uvm_pagelookup(uobj, curoff); 839 840 /* null check */ 841 if (pp == NULL) 842 continue; 843 } 844 845 switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) { 846 /* 847 * XXX In these first 3 cases, we always just 848 * XXX deactivate the page. We may want to 849 * XXX handle the different cases more specifically 850 * XXX in the future. 851 */ 852 case PGO_CLEANIT|PGO_FREE: 853 case PGO_CLEANIT|PGO_DEACTIVATE: 854 case PGO_DEACTIVATE: 855 deactivate_it: 856 /* skip the page if it's loaned or wired */ 857 if (pp->loan_count != 0 || 858 pp->wire_count != 0) 859 continue; 860 861 #ifdef UBC 862 /* ...and deactivate the page. */ 863 pmap_clear_reference(pp); 864 #else 865 /* zap all mappings for the page. */ 866 pmap_page_protect(pp, VM_PROT_NONE); 867 868 /* ...and deactivate the page. */ 869 #endif 870 uvm_pagedeactivate(pp); 871 872 continue; 873 874 case PGO_FREE: 875 /* 876 * If there are multiple references to 877 * the object, just deactivate the page. 878 */ 879 if (uobj->uo_refs > 1) 880 goto deactivate_it; 881 882 /* XXX skip the page if it's loaned or wired */ 883 if (pp->loan_count != 0 || 884 pp->wire_count != 0) 885 continue; 886 887 /* 888 * mark the page as released if its busy. 889 */ 890 if (pp->pg_flags & PG_BUSY) { 891 atomic_setbits_int(&pp->pg_flags, PG_RELEASED); 892 continue; 893 } 894 895 /* zap all mappings for the page. */ 896 pmap_page_protect(pp, VM_PROT_NONE); 897 898 uao_dropswap(uobj, pp->offset >> PAGE_SHIFT); 899 uvm_pagefree(pp); 900 901 continue; 902 903 default: 904 panic("uao_flush: weird flags"); 905 } 906 } 907 908 uvm_unlock_pageq(); 909 910 UVMHIST_LOG(maphist, 911 "<- done, rv=%ld",retval,0,0,0); 912 return (retval); 913 } 914 915 /* 916 * uao_get: fetch me a page 917 * 918 * we have three cases: 919 * 1: page is resident -> just return the page. 920 * 2: page is zero-fill -> allocate a new page and zero it. 921 * 3: page is swapped out -> fetch the page from swap. 922 * 923 * cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot. 924 * so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES), 925 * then we will need to return VM_PAGER_UNLOCK. 926 * 927 * => prefer map unlocked (not required) 928 * => object must be locked! we will _unlock_ it before starting any I/O. 929 * => flags: PGO_ALLPAGES: get all of the pages 930 * PGO_LOCKED: fault data structures are locked 931 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx] 932 * => NOTE: caller must check for released pages!! 933 */ 934 static int 935 uao_get(struct uvm_object *uobj, voff_t offset, struct vm_page **pps, 936 int *npagesp, int centeridx, vm_prot_t access_type, int advice, int flags) 937 { 938 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 939 voff_t current_offset; 940 vm_page_t ptmp; 941 int lcv, gotpages, maxpages, swslot, rv, pageidx; 942 boolean_t done; 943 UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist); 944 945 UVMHIST_LOG(pdhist, "aobj=%p offset=%ld, flags=%ld", 946 aobj, (u_long)offset, flags,0); 947 948 /* 949 * get number of pages 950 */ 951 maxpages = *npagesp; 952 953 /* 954 * step 1: handled the case where fault data structures are locked. 955 */ 956 957 if (flags & PGO_LOCKED) { 958 /* 959 * step 1a: get pages that are already resident. only do 960 * this if the data structures are locked (i.e. the first 961 * time through). 962 */ 963 964 done = TRUE; /* be optimistic */ 965 gotpages = 0; /* # of pages we got so far */ 966 967 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 968 lcv++, current_offset += PAGE_SIZE) { 969 /* do we care about this page? if not, skip it */ 970 if (pps[lcv] == PGO_DONTCARE) 971 continue; 972 973 ptmp = uvm_pagelookup(uobj, current_offset); 974 975 /* 976 * if page is new, attempt to allocate the page, 977 * zero-fill'd. 978 */ 979 if (ptmp == NULL && uao_find_swslot(aobj, 980 current_offset >> PAGE_SHIFT) == 0) { 981 ptmp = uvm_pagealloc(uobj, current_offset, 982 NULL, UVM_PGA_ZERO); 983 if (ptmp) { 984 /* new page */ 985 atomic_clearbits_int(&ptmp->pg_flags, 986 PG_BUSY|PG_FAKE); 987 atomic_setbits_int(&ptmp->pg_flags, 988 PQ_AOBJ); 989 UVM_PAGE_OWN(ptmp, NULL); 990 } 991 } 992 993 /* 994 * to be useful must get a non-busy, non-released page 995 */ 996 if (ptmp == NULL || 997 (ptmp->pg_flags & (PG_BUSY|PG_RELEASED)) != 0) { 998 if (lcv == centeridx || 999 (flags & PGO_ALLPAGES) != 0) 1000 /* need to do a wait or I/O! */ 1001 done = FALSE; 1002 continue; 1003 } 1004 1005 /* 1006 * useful page: busy/lock it and plug it in our 1007 * result array 1008 */ 1009 /* caller must un-busy this page */ 1010 atomic_setbits_int(&ptmp->pg_flags, PG_BUSY); 1011 UVM_PAGE_OWN(ptmp, "uao_get1"); 1012 pps[lcv] = ptmp; 1013 gotpages++; 1014 1015 } /* "for" lcv loop */ 1016 1017 /* 1018 * step 1b: now we've either done everything needed or we 1019 * to unlock and do some waiting or I/O. 1020 */ 1021 1022 UVMHIST_LOG(pdhist, "<- done (done=%ld)", done, 0,0,0); 1023 1024 *npagesp = gotpages; 1025 if (done) 1026 /* bingo! */ 1027 return(VM_PAGER_OK); 1028 else 1029 /* EEK! Need to unlock and I/O */ 1030 return(VM_PAGER_UNLOCK); 1031 } 1032 1033 /* 1034 * step 2: get non-resident or busy pages. 1035 * object is locked. data structures are unlocked. 1036 */ 1037 1038 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 1039 lcv++, current_offset += PAGE_SIZE) { 1040 1041 /* 1042 * - skip over pages we've already gotten or don't want 1043 * - skip over pages we don't _have_ to get 1044 */ 1045 1046 if (pps[lcv] != NULL || 1047 (lcv != centeridx && (flags & PGO_ALLPAGES) == 0)) 1048 continue; 1049 1050 pageidx = current_offset >> PAGE_SHIFT; 1051 1052 /* 1053 * we have yet to locate the current page (pps[lcv]). we 1054 * first look for a page that is already at the current offset. 1055 * if we find a page, we check to see if it is busy or 1056 * released. if that is the case, then we sleep on the page 1057 * until it is no longer busy or released and repeat the lookup. 1058 * if the page we found is neither busy nor released, then we 1059 * busy it (so we own it) and plug it into pps[lcv]. this 1060 * 'break's the following while loop and indicates we are 1061 * ready to move on to the next page in the "lcv" loop above. 1062 * 1063 * if we exit the while loop with pps[lcv] still set to NULL, 1064 * then it means that we allocated a new busy/fake/clean page 1065 * ptmp in the object and we need to do I/O to fill in the data. 1066 */ 1067 1068 /* top of "pps" while loop */ 1069 while (pps[lcv] == NULL) { 1070 /* look for a resident page */ 1071 ptmp = uvm_pagelookup(uobj, current_offset); 1072 1073 /* not resident? allocate one now (if we can) */ 1074 if (ptmp == NULL) { 1075 1076 ptmp = uvm_pagealloc(uobj, current_offset, 1077 NULL, 0); 1078 1079 /* out of RAM? */ 1080 if (ptmp == NULL) { 1081 simple_unlock(&uobj->vmobjlock); 1082 UVMHIST_LOG(pdhist, 1083 "sleeping, ptmp == NULL\n",0,0,0,0); 1084 uvm_wait("uao_getpage"); 1085 simple_lock(&uobj->vmobjlock); 1086 /* goto top of pps while loop */ 1087 continue; 1088 } 1089 1090 /* 1091 * safe with PQ's unlocked: because we just 1092 * alloc'd the page 1093 */ 1094 atomic_setbits_int(&ptmp->pg_flags, PQ_AOBJ); 1095 1096 /* 1097 * got new page ready for I/O. break pps while 1098 * loop. pps[lcv] is still NULL. 1099 */ 1100 break; 1101 } 1102 1103 /* page is there, see if we need to wait on it */ 1104 if ((ptmp->pg_flags & (PG_BUSY|PG_RELEASED)) != 0) { 1105 atomic_setbits_int(&ptmp->pg_flags, PG_WANTED); 1106 UVMHIST_LOG(pdhist, 1107 "sleeping, ptmp->flags 0x%lx\n", 1108 ptmp->pg_flags,0,0,0); 1109 UVM_UNLOCK_AND_WAIT(ptmp, &uobj->vmobjlock, 1110 FALSE, "uao_get", 0); 1111 simple_lock(&uobj->vmobjlock); 1112 continue; /* goto top of pps while loop */ 1113 } 1114 1115 /* 1116 * if we get here then the page has become resident and 1117 * unbusy between steps 1 and 2. we busy it now (so we 1118 * own it) and set pps[lcv] (so that we exit the while 1119 * loop). 1120 */ 1121 /* we own it, caller must un-busy */ 1122 atomic_setbits_int(&ptmp->pg_flags, PG_BUSY); 1123 UVM_PAGE_OWN(ptmp, "uao_get2"); 1124 pps[lcv] = ptmp; 1125 } 1126 1127 /* 1128 * if we own the valid page at the correct offset, pps[lcv] will 1129 * point to it. nothing more to do except go to the next page. 1130 */ 1131 if (pps[lcv]) 1132 continue; /* next lcv */ 1133 1134 /* 1135 * we have a "fake/busy/clean" page that we just allocated. 1136 * do the needed "i/o", either reading from swap or zeroing. 1137 */ 1138 swslot = uao_find_swslot(aobj, pageidx); 1139 1140 /* 1141 * just zero the page if there's nothing in swap. 1142 */ 1143 if (swslot == 0) 1144 { 1145 /* 1146 * page hasn't existed before, just zero it. 1147 */ 1148 uvm_pagezero(ptmp); 1149 } else { 1150 UVMHIST_LOG(pdhist, "pagein from swslot %ld", 1151 swslot, 0,0,0); 1152 1153 /* 1154 * page in the swapped-out page. 1155 * unlock object for i/o, relock when done. 1156 */ 1157 simple_unlock(&uobj->vmobjlock); 1158 rv = uvm_swap_get(ptmp, swslot, PGO_SYNCIO); 1159 simple_lock(&uobj->vmobjlock); 1160 1161 /* 1162 * I/O done. check for errors. 1163 */ 1164 if (rv != VM_PAGER_OK) 1165 { 1166 UVMHIST_LOG(pdhist, "<- done (error=%ld)", 1167 rv,0,0,0); 1168 if (ptmp->pg_flags & PG_WANTED) 1169 wakeup(ptmp); 1170 1171 /* 1172 * remove the swap slot from the aobj 1173 * and mark the aobj as having no real slot. 1174 * don't free the swap slot, thus preventing 1175 * it from being used again. 1176 */ 1177 swslot = uao_set_swslot(&aobj->u_obj, pageidx, 1178 SWSLOT_BAD); 1179 uvm_swap_markbad(swslot, 1); 1180 1181 atomic_clearbits_int(&ptmp->pg_flags, 1182 PG_WANTED|PG_BUSY); 1183 UVM_PAGE_OWN(ptmp, NULL); 1184 uvm_lock_pageq(); 1185 uvm_pagefree(ptmp); 1186 uvm_unlock_pageq(); 1187 1188 simple_unlock(&uobj->vmobjlock); 1189 return (rv); 1190 } 1191 } 1192 1193 /* 1194 * we got the page! clear the fake flag (indicates valid 1195 * data now in page) and plug into our result array. note 1196 * that page is still busy. 1197 * 1198 * it is the callers job to: 1199 * => check if the page is released 1200 * => unbusy the page 1201 * => activate the page 1202 */ 1203 1204 /* data is valid ... */ 1205 atomic_clearbits_int(&ptmp->pg_flags, PG_FAKE); 1206 pmap_clear_modify(ptmp); /* ... and clean */ 1207 pps[lcv] = ptmp; 1208 1209 } /* lcv loop */ 1210 1211 /* 1212 * finally, unlock object and return. 1213 */ 1214 1215 simple_unlock(&uobj->vmobjlock); 1216 UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0); 1217 return(VM_PAGER_OK); 1218 } 1219 1220 /* 1221 * uao_releasepg: handle released page in an aobj 1222 * 1223 * => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need 1224 * to dispose of. 1225 * => caller must handle PG_WANTED case 1226 * => called with page's object locked, pageq's unlocked 1227 * => returns TRUE if page's object is still alive, FALSE if we 1228 * killed the page's object. if we return TRUE, then we 1229 * return with the object locked. 1230 * => if (nextpgp != NULL) => we return the next page on the queue, and return 1231 * with the page queues locked [for pagedaemon] 1232 * => if (nextpgp == NULL) => we return with page queues unlocked [normal case] 1233 * => we kill the aobj if it is not referenced and we are suppose to 1234 * kill it ("KILLME"). 1235 */ 1236 static boolean_t 1237 uao_releasepg(struct vm_page *pg, struct vm_page **nextpgp /* OUT */) 1238 { 1239 struct uvm_aobj *aobj = (struct uvm_aobj *) pg->uobject; 1240 1241 KASSERT(pg->pg_flags & PG_RELEASED); 1242 1243 /* 1244 * dispose of the page [caller handles PG_WANTED] and swap slot. 1245 */ 1246 pmap_page_protect(pg, VM_PROT_NONE); 1247 uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT); 1248 uvm_lock_pageq(); 1249 if (nextpgp) 1250 *nextpgp = TAILQ_NEXT(pg, pageq); /* next page for daemon */ 1251 uvm_pagefree(pg); 1252 if (!nextpgp) 1253 uvm_unlock_pageq(); /* keep locked for daemon */ 1254 1255 /* 1256 * if we're not killing the object, we're done. 1257 */ 1258 if ((aobj->u_flags & UAO_FLAG_KILLME) == 0) 1259 return TRUE; 1260 KASSERT(aobj->u_obj.uo_refs == 0); 1261 1262 /* 1263 * if there are still pages in the object, we're done for now. 1264 */ 1265 if (aobj->u_obj.uo_npages != 0) 1266 return TRUE; 1267 1268 KASSERT(TAILQ_EMPTY(&aobj->u_obj.memq)); 1269 1270 /* 1271 * finally, free the rest. 1272 */ 1273 uao_free(aobj); 1274 1275 return FALSE; 1276 } 1277 1278 1279 /* 1280 * uao_dropswap: release any swap resources from this aobj page. 1281 * 1282 * => aobj must be locked or have a reference count of 0. 1283 */ 1284 1285 void 1286 uao_dropswap(struct uvm_object *uobj, int pageidx) 1287 { 1288 int slot; 1289 1290 slot = uao_set_swslot(uobj, pageidx, 0); 1291 if (slot) { 1292 uvm_swap_free(slot, 1); 1293 } 1294 } 1295 1296 1297 /* 1298 * page in every page in every aobj that is paged-out to a range of swslots. 1299 * 1300 * => nothing should be locked. 1301 * => returns TRUE if pagein was aborted due to lack of memory. 1302 */ 1303 boolean_t 1304 uao_swap_off(int startslot, int endslot) 1305 { 1306 struct uvm_aobj *aobj, *nextaobj; 1307 1308 /* 1309 * walk the list of all aobjs. 1310 */ 1311 1312 restart: 1313 simple_lock(&uao_list_lock); 1314 1315 for (aobj = LIST_FIRST(&uao_list); 1316 aobj != NULL; 1317 aobj = nextaobj) { 1318 boolean_t rv; 1319 1320 /* 1321 * try to get the object lock, 1322 * start all over if we fail. 1323 * most of the time we'll get the aobj lock, 1324 * so this should be a rare case. 1325 */ 1326 if (!simple_lock_try(&aobj->u_obj.vmobjlock)) { 1327 simple_unlock(&uao_list_lock); 1328 goto restart; 1329 } 1330 1331 /* 1332 * add a ref to the aobj so it doesn't disappear 1333 * while we're working. 1334 */ 1335 uao_reference_locked(&aobj->u_obj); 1336 1337 /* 1338 * now it's safe to unlock the uao list. 1339 */ 1340 simple_unlock(&uao_list_lock); 1341 1342 /* 1343 * page in any pages in the swslot range. 1344 * if there's an error, abort and return the error. 1345 */ 1346 rv = uao_pagein(aobj, startslot, endslot); 1347 if (rv) { 1348 uao_detach_locked(&aobj->u_obj); 1349 return rv; 1350 } 1351 1352 /* 1353 * we're done with this aobj. 1354 * relock the list and drop our ref on the aobj. 1355 */ 1356 simple_lock(&uao_list_lock); 1357 nextaobj = LIST_NEXT(aobj, u_list); 1358 uao_detach_locked(&aobj->u_obj); 1359 } 1360 1361 /* 1362 * done with traversal, unlock the list 1363 */ 1364 simple_unlock(&uao_list_lock); 1365 return FALSE; 1366 } 1367 1368 1369 /* 1370 * page in any pages from aobj in the given range. 1371 * 1372 * => aobj must be locked and is returned locked. 1373 * => returns TRUE if pagein was aborted due to lack of memory. 1374 */ 1375 static boolean_t 1376 uao_pagein(struct uvm_aobj *aobj, int startslot, int endslot) 1377 { 1378 boolean_t rv; 1379 1380 if (UAO_USES_SWHASH(aobj)) { 1381 struct uao_swhash_elt *elt; 1382 int bucket; 1383 1384 restart: 1385 for (bucket = aobj->u_swhashmask; bucket >= 0; bucket--) { 1386 for (elt = LIST_FIRST(&aobj->u_swhash[bucket]); 1387 elt != NULL; 1388 elt = LIST_NEXT(elt, list)) { 1389 int i; 1390 1391 for (i = 0; i < UAO_SWHASH_CLUSTER_SIZE; i++) { 1392 int slot = elt->slots[i]; 1393 1394 /* 1395 * if the slot isn't in range, skip it. 1396 */ 1397 if (slot < startslot || 1398 slot >= endslot) { 1399 continue; 1400 } 1401 1402 /* 1403 * process the page, 1404 * the start over on this object 1405 * since the swhash elt 1406 * may have been freed. 1407 */ 1408 rv = uao_pagein_page(aobj, 1409 UAO_SWHASH_ELT_PAGEIDX_BASE(elt) + i); 1410 if (rv) { 1411 return rv; 1412 } 1413 goto restart; 1414 } 1415 } 1416 } 1417 } else { 1418 int i; 1419 1420 for (i = 0; i < aobj->u_pages; i++) { 1421 int slot = aobj->u_swslots[i]; 1422 1423 /* 1424 * if the slot isn't in range, skip it 1425 */ 1426 if (slot < startslot || slot >= endslot) { 1427 continue; 1428 } 1429 1430 /* 1431 * process the page. 1432 */ 1433 rv = uao_pagein_page(aobj, i); 1434 if (rv) { 1435 return rv; 1436 } 1437 } 1438 } 1439 1440 return FALSE; 1441 } 1442 1443 /* 1444 * page in a page from an aobj. used for swap_off. 1445 * returns TRUE if pagein was aborted due to lack of memory. 1446 * 1447 * => aobj must be locked and is returned locked. 1448 */ 1449 static boolean_t 1450 uao_pagein_page(struct uvm_aobj *aobj, int pageidx) 1451 { 1452 struct vm_page *pg; 1453 int rv, slot, npages; 1454 1455 pg = NULL; 1456 npages = 1; 1457 /* locked: aobj */ 1458 rv = uao_get(&aobj->u_obj, pageidx << PAGE_SHIFT, 1459 &pg, &npages, 0, VM_PROT_READ|VM_PROT_WRITE, 0, 0); 1460 /* unlocked: aobj */ 1461 1462 /* 1463 * relock and finish up. 1464 */ 1465 simple_lock(&aobj->u_obj.vmobjlock); 1466 1467 switch (rv) { 1468 case VM_PAGER_OK: 1469 break; 1470 1471 case VM_PAGER_ERROR: 1472 case VM_PAGER_REFAULT: 1473 /* 1474 * nothing more to do on errors. 1475 * VM_PAGER_REFAULT can only mean that the anon was freed, 1476 * so again there's nothing to do. 1477 */ 1478 return FALSE; 1479 1480 } 1481 KASSERT((pg->pg_flags & PG_RELEASED) == 0); 1482 1483 /* 1484 * ok, we've got the page now. 1485 * mark it as dirty, clear its swslot and un-busy it. 1486 */ 1487 slot = uao_set_swslot(&aobj->u_obj, pageidx, 0); 1488 uvm_swap_free(slot, 1); 1489 atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_CLEAN|PG_FAKE); 1490 UVM_PAGE_OWN(pg, NULL); 1491 1492 /* 1493 * deactivate the page (to put it on a page queue). 1494 */ 1495 pmap_clear_reference(pg); 1496 #ifndef UBC 1497 pmap_page_protect(pg, VM_PROT_NONE); 1498 #endif 1499 uvm_lock_pageq(); 1500 uvm_pagedeactivate(pg); 1501 uvm_unlock_pageq(); 1502 1503 return FALSE; 1504 } 1505