1 /* $NetBSD: uvm_aobj.c,v 1.122 2014/05/25 18:55:11 riastradh Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Chuck Silvers, Charles D. Cranor and 5 * 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp 29 */ 30 31 /* 32 * uvm_aobj.c: anonymous memory uvm_object pager 33 * 34 * author: Chuck Silvers <chuq@chuq.com> 35 * started: Jan-1998 36 * 37 * - design mostly from Chuck Cranor 38 */ 39 40 #include <sys/cdefs.h> 41 __KERNEL_RCSID(0, "$NetBSD: uvm_aobj.c,v 1.122 2014/05/25 18:55:11 riastradh Exp $"); 42 43 #include "opt_uvmhist.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kernel.h> 48 #include <sys/kmem.h> 49 #include <sys/pool.h> 50 #include <sys/atomic.h> 51 52 #include <uvm/uvm.h> 53 54 /* 55 * An anonymous UVM object (aobj) manages anonymous-memory. In addition to 56 * keeping the list of resident pages, it may also keep a list of allocated 57 * swap blocks. Depending on the size of the object, this list is either 58 * stored in an array (small objects) or in a hash table (large objects). 59 * 60 * Lock order 61 * 62 * uao_list_lock -> 63 * uvm_object::vmobjlock 64 */ 65 66 /* 67 * Note: for hash tables, we break the address space of the aobj into blocks 68 * of UAO_SWHASH_CLUSTER_SIZE pages, which shall be a power of two. 69 */ 70 71 #define UAO_SWHASH_CLUSTER_SHIFT 4 72 #define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT) 73 74 /* Get the "tag" for this page index. */ 75 #define UAO_SWHASH_ELT_TAG(idx) ((idx) >> UAO_SWHASH_CLUSTER_SHIFT) 76 #define UAO_SWHASH_ELT_PAGESLOT_IDX(idx) \ 77 ((idx) & (UAO_SWHASH_CLUSTER_SIZE - 1)) 78 79 /* Given an ELT and a page index, find the swap slot. */ 80 #define UAO_SWHASH_ELT_PAGESLOT(elt, idx) \ 81 ((elt)->slots[UAO_SWHASH_ELT_PAGESLOT_IDX(idx)]) 82 83 /* Given an ELT, return its pageidx base. */ 84 #define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \ 85 ((elt)->tag << UAO_SWHASH_CLUSTER_SHIFT) 86 87 /* The hash function. */ 88 #define UAO_SWHASH_HASH(aobj, idx) \ 89 (&(aobj)->u_swhash[(((idx) >> UAO_SWHASH_CLUSTER_SHIFT) \ 90 & (aobj)->u_swhashmask)]) 91 92 /* 93 * The threshold which determines whether we will use an array or a 94 * hash table to store the list of allocated swap blocks. 95 */ 96 #define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4) 97 #define UAO_USES_SWHASH(aobj) \ 98 ((aobj)->u_pages > UAO_SWHASH_THRESHOLD) 99 100 /* The number of buckets in a hash, with an upper bound. */ 101 #define UAO_SWHASH_MAXBUCKETS 256 102 #define UAO_SWHASH_BUCKETS(aobj) \ 103 (MIN((aobj)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, UAO_SWHASH_MAXBUCKETS)) 104 105 /* 106 * uao_swhash_elt: when a hash table is being used, this structure defines 107 * the format of an entry in the bucket list. 108 */ 109 110 struct uao_swhash_elt { 111 LIST_ENTRY(uao_swhash_elt) list; /* the hash list */ 112 voff_t tag; /* our 'tag' */ 113 int count; /* our number of active slots */ 114 int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */ 115 }; 116 117 /* 118 * uao_swhash: the swap hash table structure 119 */ 120 121 LIST_HEAD(uao_swhash, uao_swhash_elt); 122 123 /* 124 * uao_swhash_elt_pool: pool of uao_swhash_elt structures. 125 * Note: pages for this pool must not come from a pageable kernel map. 126 */ 127 static struct pool uao_swhash_elt_pool __cacheline_aligned; 128 129 /* 130 * uvm_aobj: the actual anon-backed uvm_object 131 * 132 * => the uvm_object is at the top of the structure, this allows 133 * (struct uvm_aobj *) == (struct uvm_object *) 134 * => only one of u_swslots and u_swhash is used in any given aobj 135 */ 136 137 struct uvm_aobj { 138 struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */ 139 pgoff_t u_pages; /* number of pages in entire object */ 140 int u_flags; /* the flags (see uvm_aobj.h) */ 141 int *u_swslots; /* array of offset->swapslot mappings */ 142 /* 143 * hashtable of offset->swapslot mappings 144 * (u_swhash is an array of bucket heads) 145 */ 146 struct uao_swhash *u_swhash; 147 u_long u_swhashmask; /* mask for hashtable */ 148 LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */ 149 int u_freelist; /* freelist to allocate pages from */ 150 }; 151 152 static void uao_free(struct uvm_aobj *); 153 static int uao_get(struct uvm_object *, voff_t, struct vm_page **, 154 int *, int, vm_prot_t, int, int); 155 static int uao_put(struct uvm_object *, voff_t, voff_t, int); 156 157 #if defined(VMSWAP) 158 static struct uao_swhash_elt *uao_find_swhash_elt 159 (struct uvm_aobj *, int, bool); 160 161 static bool uao_pagein(struct uvm_aobj *, int, int); 162 static bool uao_pagein_page(struct uvm_aobj *, int); 163 #endif /* defined(VMSWAP) */ 164 165 static struct vm_page *uao_pagealloc(struct uvm_object *, voff_t, int); 166 167 /* 168 * aobj_pager 169 * 170 * note that some functions (e.g. put) are handled elsewhere 171 */ 172 173 const struct uvm_pagerops aobj_pager = { 174 .pgo_reference = uao_reference, 175 .pgo_detach = uao_detach, 176 .pgo_get = uao_get, 177 .pgo_put = uao_put, 178 }; 179 180 /* 181 * uao_list: global list of active aobjs, locked by uao_list_lock 182 */ 183 184 static LIST_HEAD(aobjlist, uvm_aobj) uao_list __cacheline_aligned; 185 static kmutex_t uao_list_lock __cacheline_aligned; 186 187 /* 188 * hash table/array related functions 189 */ 190 191 #if defined(VMSWAP) 192 193 /* 194 * uao_find_swhash_elt: find (or create) a hash table entry for a page 195 * offset. 196 * 197 * => the object should be locked by the caller 198 */ 199 200 static struct uao_swhash_elt * 201 uao_find_swhash_elt(struct uvm_aobj *aobj, int pageidx, bool create) 202 { 203 struct uao_swhash *swhash; 204 struct uao_swhash_elt *elt; 205 voff_t page_tag; 206 207 swhash = UAO_SWHASH_HASH(aobj, pageidx); 208 page_tag = UAO_SWHASH_ELT_TAG(pageidx); 209 210 /* 211 * now search the bucket for the requested tag 212 */ 213 214 LIST_FOREACH(elt, swhash, list) { 215 if (elt->tag == page_tag) { 216 return elt; 217 } 218 } 219 if (!create) { 220 return NULL; 221 } 222 223 /* 224 * allocate a new entry for the bucket and init/insert it in 225 */ 226 227 elt = pool_get(&uao_swhash_elt_pool, PR_NOWAIT); 228 if (elt == NULL) { 229 return NULL; 230 } 231 LIST_INSERT_HEAD(swhash, elt, list); 232 elt->tag = page_tag; 233 elt->count = 0; 234 memset(elt->slots, 0, sizeof(elt->slots)); 235 return elt; 236 } 237 238 /* 239 * uao_find_swslot: find the swap slot number for an aobj/pageidx 240 * 241 * => object must be locked by caller 242 */ 243 244 int 245 uao_find_swslot(struct uvm_object *uobj, int pageidx) 246 { 247 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 248 struct uao_swhash_elt *elt; 249 250 /* 251 * if noswap flag is set, then we never return a slot 252 */ 253 254 if (aobj->u_flags & UAO_FLAG_NOSWAP) 255 return 0; 256 257 /* 258 * if hashing, look in hash table. 259 */ 260 261 if (UAO_USES_SWHASH(aobj)) { 262 elt = uao_find_swhash_elt(aobj, pageidx, false); 263 return elt ? UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) : 0; 264 } 265 266 /* 267 * otherwise, look in the array 268 */ 269 270 return aobj->u_swslots[pageidx]; 271 } 272 273 /* 274 * uao_set_swslot: set the swap slot for a page in an aobj. 275 * 276 * => setting a slot to zero frees the slot 277 * => object must be locked by caller 278 * => we return the old slot number, or -1 if we failed to allocate 279 * memory to record the new slot number 280 */ 281 282 int 283 uao_set_swslot(struct uvm_object *uobj, int pageidx, int slot) 284 { 285 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 286 struct uao_swhash_elt *elt; 287 int oldslot; 288 UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist); 289 UVMHIST_LOG(pdhist, "aobj %p pageidx %d slot %d", 290 aobj, pageidx, slot, 0); 291 292 KASSERT(mutex_owned(uobj->vmobjlock) || uobj->uo_refs == 0); 293 294 /* 295 * if noswap flag is set, then we can't set a non-zero slot. 296 */ 297 298 if (aobj->u_flags & UAO_FLAG_NOSWAP) { 299 KASSERTMSG(slot == 0, "uao_set_swslot: no swap object"); 300 return 0; 301 } 302 303 /* 304 * are we using a hash table? if so, add it in the hash. 305 */ 306 307 if (UAO_USES_SWHASH(aobj)) { 308 309 /* 310 * Avoid allocating an entry just to free it again if 311 * the page had not swap slot in the first place, and 312 * we are freeing. 313 */ 314 315 elt = uao_find_swhash_elt(aobj, pageidx, slot != 0); 316 if (elt == NULL) { 317 return slot ? -1 : 0; 318 } 319 320 oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx); 321 UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot; 322 323 /* 324 * now adjust the elt's reference counter and free it if we've 325 * dropped it to zero. 326 */ 327 328 if (slot) { 329 if (oldslot == 0) 330 elt->count++; 331 } else { 332 if (oldslot) 333 elt->count--; 334 335 if (elt->count == 0) { 336 LIST_REMOVE(elt, list); 337 pool_put(&uao_swhash_elt_pool, elt); 338 } 339 } 340 } else { 341 /* we are using an array */ 342 oldslot = aobj->u_swslots[pageidx]; 343 aobj->u_swslots[pageidx] = slot; 344 } 345 return oldslot; 346 } 347 348 #endif /* defined(VMSWAP) */ 349 350 /* 351 * end of hash/array functions 352 */ 353 354 /* 355 * uao_free: free all resources held by an aobj, and then free the aobj 356 * 357 * => the aobj should be dead 358 */ 359 360 static void 361 uao_free(struct uvm_aobj *aobj) 362 { 363 struct uvm_object *uobj = &aobj->u_obj; 364 365 KASSERT(mutex_owned(uobj->vmobjlock)); 366 uao_dropswap_range(uobj, 0, 0); 367 mutex_exit(uobj->vmobjlock); 368 369 #if defined(VMSWAP) 370 if (UAO_USES_SWHASH(aobj)) { 371 372 /* 373 * free the hash table itself. 374 */ 375 376 hashdone(aobj->u_swhash, HASH_LIST, aobj->u_swhashmask); 377 } else { 378 379 /* 380 * free the array itsself. 381 */ 382 383 kmem_free(aobj->u_swslots, aobj->u_pages * sizeof(int)); 384 } 385 #endif /* defined(VMSWAP) */ 386 387 /* 388 * finally free the aobj itself 389 */ 390 391 uvm_obj_destroy(uobj, true); 392 kmem_free(aobj, sizeof(struct uvm_aobj)); 393 } 394 395 /* 396 * pager functions 397 */ 398 399 /* 400 * uao_create: create an aobj of the given size and return its uvm_object. 401 * 402 * => for normal use, flags are always zero 403 * => for the kernel object, the flags are: 404 * UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once) 405 * UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ") 406 */ 407 408 struct uvm_object * 409 uao_create(vsize_t size, int flags) 410 { 411 static struct uvm_aobj kernel_object_store; 412 static kmutex_t kernel_object_lock; 413 static int kobj_alloced __diagused = 0; 414 pgoff_t pages = round_page(size) >> PAGE_SHIFT; 415 struct uvm_aobj *aobj; 416 int refs; 417 418 /* 419 * Allocate a new aobj, unless kernel object is requested. 420 */ 421 422 if (flags & UAO_FLAG_KERNOBJ) { 423 KASSERT(!kobj_alloced); 424 aobj = &kernel_object_store; 425 aobj->u_pages = pages; 426 aobj->u_flags = UAO_FLAG_NOSWAP; 427 refs = UVM_OBJ_KERN; 428 kobj_alloced = UAO_FLAG_KERNOBJ; 429 } else if (flags & UAO_FLAG_KERNSWAP) { 430 KASSERT(kobj_alloced == UAO_FLAG_KERNOBJ); 431 aobj = &kernel_object_store; 432 kobj_alloced = UAO_FLAG_KERNSWAP; 433 refs = 0xdeadbeaf; /* XXX: gcc */ 434 } else { 435 aobj = kmem_alloc(sizeof(struct uvm_aobj), KM_SLEEP); 436 aobj->u_pages = pages; 437 aobj->u_flags = 0; 438 refs = 1; 439 } 440 441 /* 442 * no freelist by default 443 */ 444 445 aobj->u_freelist = VM_NFREELIST; 446 447 /* 448 * allocate hash/array if necessary 449 * 450 * note: in the KERNSWAP case no need to worry about locking since 451 * we are still booting we should be the only thread around. 452 */ 453 454 if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) { 455 #if defined(VMSWAP) 456 const int kernswap = (flags & UAO_FLAG_KERNSWAP) != 0; 457 458 /* allocate hash table or array depending on object size */ 459 if (UAO_USES_SWHASH(aobj)) { 460 aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj), 461 HASH_LIST, kernswap ? false : true, 462 &aobj->u_swhashmask); 463 if (aobj->u_swhash == NULL) 464 panic("uao_create: hashinit swhash failed"); 465 } else { 466 aobj->u_swslots = kmem_zalloc(pages * sizeof(int), 467 kernswap ? KM_NOSLEEP : KM_SLEEP); 468 if (aobj->u_swslots == NULL) 469 panic("uao_create: swslots allocation failed"); 470 } 471 #endif /* defined(VMSWAP) */ 472 473 if (flags) { 474 aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */ 475 return &aobj->u_obj; 476 } 477 } 478 479 /* 480 * Initialise UVM object. 481 */ 482 483 const bool kernobj = (flags & UAO_FLAG_KERNOBJ) != 0; 484 uvm_obj_init(&aobj->u_obj, &aobj_pager, !kernobj, refs); 485 if (__predict_false(kernobj)) { 486 /* Initialisation only once, for UAO_FLAG_KERNOBJ. */ 487 mutex_init(&kernel_object_lock, MUTEX_DEFAULT, IPL_NONE); 488 uvm_obj_setlock(&aobj->u_obj, &kernel_object_lock); 489 } 490 491 /* 492 * now that aobj is ready, add it to the global list 493 */ 494 495 mutex_enter(&uao_list_lock); 496 LIST_INSERT_HEAD(&uao_list, aobj, u_list); 497 mutex_exit(&uao_list_lock); 498 return(&aobj->u_obj); 499 } 500 501 /* 502 * uao_set_pgfl: allocate pages only from the specified freelist. 503 * 504 * => must be called before any pages are allocated for the object. 505 * => reset by setting it to VM_NFREELIST, meaning any freelist. 506 */ 507 508 void 509 uao_set_pgfl(struct uvm_object *uobj, int freelist) 510 { 511 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 512 513 KASSERTMSG((0 <= freelist), "invalid freelist %d", freelist); 514 KASSERTMSG((freelist <= VM_NFREELIST), "invalid freelist %d", 515 freelist); 516 517 aobj->u_freelist = freelist; 518 } 519 520 /* 521 * uao_pagealloc: allocate a page for aobj. 522 */ 523 524 static inline struct vm_page * 525 uao_pagealloc(struct uvm_object *uobj, voff_t offset, int flags) 526 { 527 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 528 529 if (__predict_true(aobj->u_freelist == VM_NFREELIST)) 530 return uvm_pagealloc(uobj, offset, NULL, flags); 531 else 532 return uvm_pagealloc_strat(uobj, offset, NULL, flags, 533 UVM_PGA_STRAT_ONLY, aobj->u_freelist); 534 } 535 536 /* 537 * uao_init: set up aobj pager subsystem 538 * 539 * => called at boot time from uvm_pager_init() 540 */ 541 542 void 543 uao_init(void) 544 { 545 static int uao_initialized; 546 547 if (uao_initialized) 548 return; 549 uao_initialized = true; 550 LIST_INIT(&uao_list); 551 mutex_init(&uao_list_lock, MUTEX_DEFAULT, IPL_NONE); 552 pool_init(&uao_swhash_elt_pool, sizeof(struct uao_swhash_elt), 553 0, 0, 0, "uaoeltpl", NULL, IPL_VM); 554 } 555 556 /* 557 * uao_reference: hold a reference to an anonymous UVM object. 558 */ 559 void 560 uao_reference(struct uvm_object *uobj) 561 { 562 /* Kernel object is persistent. */ 563 if (UVM_OBJ_IS_KERN_OBJECT(uobj)) { 564 return; 565 } 566 atomic_inc_uint(&uobj->uo_refs); 567 } 568 569 /* 570 * uao_detach: drop a reference to an anonymous UVM object. 571 */ 572 void 573 uao_detach(struct uvm_object *uobj) 574 { 575 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 576 struct vm_page *pg; 577 578 UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist); 579 580 /* 581 * Detaching from kernel object is a NOP. 582 */ 583 584 if (UVM_OBJ_IS_KERN_OBJECT(uobj)) 585 return; 586 587 /* 588 * Drop the reference. If it was the last one, destroy the object. 589 */ 590 591 UVMHIST_LOG(maphist," (uobj=0x%x) ref=%d", uobj,uobj->uo_refs,0,0); 592 if (atomic_dec_uint_nv(&uobj->uo_refs) > 0) { 593 UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0); 594 return; 595 } 596 597 /* 598 * Remove the aobj from the global list. 599 */ 600 601 mutex_enter(&uao_list_lock); 602 LIST_REMOVE(aobj, u_list); 603 mutex_exit(&uao_list_lock); 604 605 /* 606 * Free all the pages left in the aobj. For each page, when the 607 * page is no longer busy (and thus after any disk I/O that it is 608 * involved in is complete), release any swap resources and free 609 * the page itself. 610 */ 611 612 mutex_enter(uobj->vmobjlock); 613 mutex_enter(&uvm_pageqlock); 614 while ((pg = TAILQ_FIRST(&uobj->memq)) != NULL) { 615 pmap_page_protect(pg, VM_PROT_NONE); 616 if (pg->flags & PG_BUSY) { 617 pg->flags |= PG_WANTED; 618 mutex_exit(&uvm_pageqlock); 619 UVM_UNLOCK_AND_WAIT(pg, uobj->vmobjlock, false, 620 "uao_det", 0); 621 mutex_enter(uobj->vmobjlock); 622 mutex_enter(&uvm_pageqlock); 623 continue; 624 } 625 uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT); 626 uvm_pagefree(pg); 627 } 628 mutex_exit(&uvm_pageqlock); 629 630 /* 631 * Finally, free the anonymous UVM object itself. 632 */ 633 634 uao_free(aobj); 635 } 636 637 /* 638 * uao_put: flush pages out of a uvm object 639 * 640 * => object should be locked by caller. we may _unlock_ the object 641 * if (and only if) we need to clean a page (PGO_CLEANIT). 642 * XXXJRT Currently, however, we don't. In the case of cleaning 643 * XXXJRT a page, we simply just deactivate it. Should probably 644 * XXXJRT handle this better, in the future (although "flushing" 645 * XXXJRT anonymous memory isn't terribly important). 646 * => if PGO_CLEANIT is not set, then we will neither unlock the object 647 * or block. 648 * => if PGO_ALLPAGE is set, then all pages in the object are valid targets 649 * for flushing. 650 * => NOTE: we rely on the fact that the object's memq is a TAILQ and 651 * that new pages are inserted on the tail end of the list. thus, 652 * we can make a complete pass through the object in one go by starting 653 * at the head and working towards the tail (new pages are put in 654 * front of us). 655 * => NOTE: we are allowed to lock the page queues, so the caller 656 * must not be holding the lock on them [e.g. pagedaemon had 657 * better not call us with the queues locked] 658 * => we return 0 unless we encountered some sort of I/O error 659 * XXXJRT currently never happens, as we never directly initiate 660 * XXXJRT I/O 661 * 662 * note on page traversal: 663 * we can traverse the pages in an object either by going down the 664 * linked list in "uobj->memq", or we can go over the address range 665 * by page doing hash table lookups for each address. depending 666 * on how many pages are in the object it may be cheaper to do one 667 * or the other. we set "by_list" to true if we are using memq. 668 * if the cost of a hash lookup was equal to the cost of the list 669 * traversal we could compare the number of pages in the start->stop 670 * range to the total number of pages in the object. however, it 671 * seems that a hash table lookup is more expensive than the linked 672 * list traversal, so we multiply the number of pages in the 673 * start->stop range by a penalty which we define below. 674 */ 675 676 static int 677 uao_put(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) 678 { 679 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 680 struct vm_page *pg, *nextpg, curmp, endmp; 681 bool by_list; 682 voff_t curoff; 683 UVMHIST_FUNC("uao_put"); UVMHIST_CALLED(maphist); 684 685 KASSERT(mutex_owned(uobj->vmobjlock)); 686 687 curoff = 0; 688 if (flags & PGO_ALLPAGES) { 689 start = 0; 690 stop = aobj->u_pages << PAGE_SHIFT; 691 by_list = true; /* always go by the list */ 692 } else { 693 start = trunc_page(start); 694 if (stop == 0) { 695 stop = aobj->u_pages << PAGE_SHIFT; 696 } else { 697 stop = round_page(stop); 698 } 699 if (stop > (aobj->u_pages << PAGE_SHIFT)) { 700 printf("uao_flush: strange, got an out of range " 701 "flush (fixed)\n"); 702 stop = aobj->u_pages << PAGE_SHIFT; 703 } 704 by_list = (uobj->uo_npages <= 705 ((stop - start) >> PAGE_SHIFT) * UVM_PAGE_TREE_PENALTY); 706 } 707 UVMHIST_LOG(maphist, 708 " flush start=0x%lx, stop=0x%x, by_list=%d, flags=0x%x", 709 start, stop, by_list, flags); 710 711 /* 712 * Don't need to do any work here if we're not freeing 713 * or deactivating pages. 714 */ 715 716 if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) { 717 mutex_exit(uobj->vmobjlock); 718 return 0; 719 } 720 721 /* 722 * Initialize the marker pages. See the comment in 723 * genfs_putpages() also. 724 */ 725 726 curmp.flags = PG_MARKER; 727 endmp.flags = PG_MARKER; 728 729 /* 730 * now do it. note: we must update nextpg in the body of loop or we 731 * will get stuck. we need to use nextpg if we'll traverse the list 732 * because we may free "pg" before doing the next loop. 733 */ 734 735 if (by_list) { 736 TAILQ_INSERT_TAIL(&uobj->memq, &endmp, listq.queue); 737 nextpg = TAILQ_FIRST(&uobj->memq); 738 } else { 739 curoff = start; 740 nextpg = NULL; /* Quell compiler warning */ 741 } 742 743 /* locked: uobj */ 744 for (;;) { 745 if (by_list) { 746 pg = nextpg; 747 if (pg == &endmp) 748 break; 749 nextpg = TAILQ_NEXT(pg, listq.queue); 750 if (pg->flags & PG_MARKER) 751 continue; 752 if (pg->offset < start || pg->offset >= stop) 753 continue; 754 } else { 755 if (curoff < stop) { 756 pg = uvm_pagelookup(uobj, curoff); 757 curoff += PAGE_SIZE; 758 } else 759 break; 760 if (pg == NULL) 761 continue; 762 } 763 764 /* 765 * wait and try again if the page is busy. 766 */ 767 768 if (pg->flags & PG_BUSY) { 769 if (by_list) { 770 TAILQ_INSERT_BEFORE(pg, &curmp, listq.queue); 771 } 772 pg->flags |= PG_WANTED; 773 UVM_UNLOCK_AND_WAIT(pg, uobj->vmobjlock, 0, 774 "uao_put", 0); 775 mutex_enter(uobj->vmobjlock); 776 if (by_list) { 777 nextpg = TAILQ_NEXT(&curmp, listq.queue); 778 TAILQ_REMOVE(&uobj->memq, &curmp, 779 listq.queue); 780 } else 781 curoff -= PAGE_SIZE; 782 continue; 783 } 784 785 switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) { 786 787 /* 788 * XXX In these first 3 cases, we always just 789 * XXX deactivate the page. We may want to 790 * XXX handle the different cases more specifically 791 * XXX in the future. 792 */ 793 794 case PGO_CLEANIT|PGO_FREE: 795 case PGO_CLEANIT|PGO_DEACTIVATE: 796 case PGO_DEACTIVATE: 797 deactivate_it: 798 mutex_enter(&uvm_pageqlock); 799 /* skip the page if it's wired */ 800 if (pg->wire_count == 0) { 801 uvm_pagedeactivate(pg); 802 } 803 mutex_exit(&uvm_pageqlock); 804 break; 805 806 case PGO_FREE: 807 /* 808 * If there are multiple references to 809 * the object, just deactivate the page. 810 */ 811 812 if (uobj->uo_refs > 1) 813 goto deactivate_it; 814 815 /* 816 * free the swap slot and the page. 817 */ 818 819 pmap_page_protect(pg, VM_PROT_NONE); 820 821 /* 822 * freeing swapslot here is not strictly necessary. 823 * however, leaving it here doesn't save much 824 * because we need to update swap accounting anyway. 825 */ 826 827 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 828 mutex_enter(&uvm_pageqlock); 829 uvm_pagefree(pg); 830 mutex_exit(&uvm_pageqlock); 831 break; 832 833 default: 834 panic("%s: impossible", __func__); 835 } 836 } 837 if (by_list) { 838 TAILQ_REMOVE(&uobj->memq, &endmp, listq.queue); 839 } 840 mutex_exit(uobj->vmobjlock); 841 return 0; 842 } 843 844 /* 845 * uao_get: fetch me a page 846 * 847 * we have three cases: 848 * 1: page is resident -> just return the page. 849 * 2: page is zero-fill -> allocate a new page and zero it. 850 * 3: page is swapped out -> fetch the page from swap. 851 * 852 * cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot. 853 * so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES), 854 * then we will need to return EBUSY. 855 * 856 * => prefer map unlocked (not required) 857 * => object must be locked! we will _unlock_ it before starting any I/O. 858 * => flags: PGO_ALLPAGES: get all of the pages 859 * PGO_LOCKED: fault data structures are locked 860 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx] 861 * => NOTE: caller must check for released pages!! 862 */ 863 864 static int 865 uao_get(struct uvm_object *uobj, voff_t offset, struct vm_page **pps, 866 int *npagesp, int centeridx, vm_prot_t access_type, int advice, int flags) 867 { 868 voff_t current_offset; 869 struct vm_page *ptmp = NULL; /* Quell compiler warning */ 870 int lcv, gotpages, maxpages, swslot, pageidx; 871 bool done; 872 UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist); 873 874 UVMHIST_LOG(pdhist, "aobj=%p offset=%d, flags=%d", 875 (struct uvm_aobj *)uobj, offset, flags,0); 876 877 /* 878 * get number of pages 879 */ 880 881 maxpages = *npagesp; 882 883 /* 884 * step 1: handled the case where fault data structures are locked. 885 */ 886 887 if (flags & PGO_LOCKED) { 888 889 /* 890 * step 1a: get pages that are already resident. only do 891 * this if the data structures are locked (i.e. the first 892 * time through). 893 */ 894 895 done = true; /* be optimistic */ 896 gotpages = 0; /* # of pages we got so far */ 897 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 898 lcv++, current_offset += PAGE_SIZE) { 899 /* do we care about this page? if not, skip it */ 900 if (pps[lcv] == PGO_DONTCARE) 901 continue; 902 ptmp = uvm_pagelookup(uobj, current_offset); 903 904 /* 905 * if page is new, attempt to allocate the page, 906 * zero-fill'd. 907 */ 908 909 if (ptmp == NULL && uao_find_swslot(uobj, 910 current_offset >> PAGE_SHIFT) == 0) { 911 ptmp = uao_pagealloc(uobj, current_offset, 912 UVM_FLAG_COLORMATCH|UVM_PGA_ZERO); 913 if (ptmp) { 914 /* new page */ 915 ptmp->flags &= ~(PG_FAKE); 916 ptmp->pqflags |= PQ_AOBJ; 917 goto gotpage; 918 } 919 } 920 921 /* 922 * to be useful must get a non-busy page 923 */ 924 925 if (ptmp == NULL || (ptmp->flags & PG_BUSY) != 0) { 926 if (lcv == centeridx || 927 (flags & PGO_ALLPAGES) != 0) 928 /* need to do a wait or I/O! */ 929 done = false; 930 continue; 931 } 932 933 /* 934 * useful page: busy/lock it and plug it in our 935 * result array 936 */ 937 938 /* caller must un-busy this page */ 939 ptmp->flags |= PG_BUSY; 940 UVM_PAGE_OWN(ptmp, "uao_get1"); 941 gotpage: 942 pps[lcv] = ptmp; 943 gotpages++; 944 } 945 946 /* 947 * step 1b: now we've either done everything needed or we 948 * to unlock and do some waiting or I/O. 949 */ 950 951 UVMHIST_LOG(pdhist, "<- done (done=%d)", done, 0,0,0); 952 *npagesp = gotpages; 953 if (done) 954 return 0; 955 else 956 return EBUSY; 957 } 958 959 /* 960 * step 2: get non-resident or busy pages. 961 * object is locked. data structures are unlocked. 962 */ 963 964 if ((flags & PGO_SYNCIO) == 0) { 965 goto done; 966 } 967 968 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 969 lcv++, current_offset += PAGE_SIZE) { 970 971 /* 972 * - skip over pages we've already gotten or don't want 973 * - skip over pages we don't _have_ to get 974 */ 975 976 if (pps[lcv] != NULL || 977 (lcv != centeridx && (flags & PGO_ALLPAGES) == 0)) 978 continue; 979 980 pageidx = current_offset >> PAGE_SHIFT; 981 982 /* 983 * we have yet to locate the current page (pps[lcv]). we 984 * first look for a page that is already at the current offset. 985 * if we find a page, we check to see if it is busy or 986 * released. if that is the case, then we sleep on the page 987 * until it is no longer busy or released and repeat the lookup. 988 * if the page we found is neither busy nor released, then we 989 * busy it (so we own it) and plug it into pps[lcv]. this 990 * 'break's the following while loop and indicates we are 991 * ready to move on to the next page in the "lcv" loop above. 992 * 993 * if we exit the while loop with pps[lcv] still set to NULL, 994 * then it means that we allocated a new busy/fake/clean page 995 * ptmp in the object and we need to do I/O to fill in the data. 996 */ 997 998 /* top of "pps" while loop */ 999 while (pps[lcv] == NULL) { 1000 /* look for a resident page */ 1001 ptmp = uvm_pagelookup(uobj, current_offset); 1002 1003 /* not resident? allocate one now (if we can) */ 1004 if (ptmp == NULL) { 1005 1006 ptmp = uao_pagealloc(uobj, current_offset, 0); 1007 1008 /* out of RAM? */ 1009 if (ptmp == NULL) { 1010 mutex_exit(uobj->vmobjlock); 1011 UVMHIST_LOG(pdhist, 1012 "sleeping, ptmp == NULL\n",0,0,0,0); 1013 uvm_wait("uao_getpage"); 1014 mutex_enter(uobj->vmobjlock); 1015 continue; 1016 } 1017 1018 /* 1019 * safe with PQ's unlocked: because we just 1020 * alloc'd the page 1021 */ 1022 1023 ptmp->pqflags |= PQ_AOBJ; 1024 1025 /* 1026 * got new page ready for I/O. break pps while 1027 * loop. pps[lcv] is still NULL. 1028 */ 1029 1030 break; 1031 } 1032 1033 /* page is there, see if we need to wait on it */ 1034 if ((ptmp->flags & PG_BUSY) != 0) { 1035 ptmp->flags |= PG_WANTED; 1036 UVMHIST_LOG(pdhist, 1037 "sleeping, ptmp->flags 0x%x\n", 1038 ptmp->flags,0,0,0); 1039 UVM_UNLOCK_AND_WAIT(ptmp, uobj->vmobjlock, 1040 false, "uao_get", 0); 1041 mutex_enter(uobj->vmobjlock); 1042 continue; 1043 } 1044 1045 /* 1046 * if we get here then the page has become resident and 1047 * unbusy between steps 1 and 2. we busy it now (so we 1048 * own it) and set pps[lcv] (so that we exit the while 1049 * loop). 1050 */ 1051 1052 /* we own it, caller must un-busy */ 1053 ptmp->flags |= PG_BUSY; 1054 UVM_PAGE_OWN(ptmp, "uao_get2"); 1055 pps[lcv] = ptmp; 1056 } 1057 1058 /* 1059 * if we own the valid page at the correct offset, pps[lcv] will 1060 * point to it. nothing more to do except go to the next page. 1061 */ 1062 1063 if (pps[lcv]) 1064 continue; /* next lcv */ 1065 1066 /* 1067 * we have a "fake/busy/clean" page that we just allocated. 1068 * do the needed "i/o", either reading from swap or zeroing. 1069 */ 1070 1071 swslot = uao_find_swslot(uobj, pageidx); 1072 1073 /* 1074 * just zero the page if there's nothing in swap. 1075 */ 1076 1077 if (swslot == 0) { 1078 1079 /* 1080 * page hasn't existed before, just zero it. 1081 */ 1082 1083 uvm_pagezero(ptmp); 1084 } else { 1085 #if defined(VMSWAP) 1086 int error; 1087 1088 UVMHIST_LOG(pdhist, "pagein from swslot %d", 1089 swslot, 0,0,0); 1090 1091 /* 1092 * page in the swapped-out page. 1093 * unlock object for i/o, relock when done. 1094 */ 1095 1096 mutex_exit(uobj->vmobjlock); 1097 error = uvm_swap_get(ptmp, swslot, PGO_SYNCIO); 1098 mutex_enter(uobj->vmobjlock); 1099 1100 /* 1101 * I/O done. check for errors. 1102 */ 1103 1104 if (error != 0) { 1105 UVMHIST_LOG(pdhist, "<- done (error=%d)", 1106 error,0,0,0); 1107 if (ptmp->flags & PG_WANTED) 1108 wakeup(ptmp); 1109 1110 /* 1111 * remove the swap slot from the aobj 1112 * and mark the aobj as having no real slot. 1113 * don't free the swap slot, thus preventing 1114 * it from being used again. 1115 */ 1116 1117 swslot = uao_set_swslot(uobj, pageidx, 1118 SWSLOT_BAD); 1119 if (swslot > 0) { 1120 uvm_swap_markbad(swslot, 1); 1121 } 1122 1123 mutex_enter(&uvm_pageqlock); 1124 uvm_pagefree(ptmp); 1125 mutex_exit(&uvm_pageqlock); 1126 mutex_exit(uobj->vmobjlock); 1127 return error; 1128 } 1129 #else /* defined(VMSWAP) */ 1130 panic("%s: pagein", __func__); 1131 #endif /* defined(VMSWAP) */ 1132 } 1133 1134 if ((access_type & VM_PROT_WRITE) == 0) { 1135 ptmp->flags |= PG_CLEAN; 1136 pmap_clear_modify(ptmp); 1137 } 1138 1139 /* 1140 * we got the page! clear the fake flag (indicates valid 1141 * data now in page) and plug into our result array. note 1142 * that page is still busy. 1143 * 1144 * it is the callers job to: 1145 * => check if the page is released 1146 * => unbusy the page 1147 * => activate the page 1148 */ 1149 1150 ptmp->flags &= ~PG_FAKE; 1151 pps[lcv] = ptmp; 1152 } 1153 1154 /* 1155 * finally, unlock object and return. 1156 */ 1157 1158 done: 1159 mutex_exit(uobj->vmobjlock); 1160 UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0); 1161 return 0; 1162 } 1163 1164 #if defined(VMSWAP) 1165 1166 /* 1167 * uao_dropswap: release any swap resources from this aobj page. 1168 * 1169 * => aobj must be locked or have a reference count of 0. 1170 */ 1171 1172 void 1173 uao_dropswap(struct uvm_object *uobj, int pageidx) 1174 { 1175 int slot; 1176 1177 slot = uao_set_swslot(uobj, pageidx, 0); 1178 if (slot) { 1179 uvm_swap_free(slot, 1); 1180 } 1181 } 1182 1183 /* 1184 * page in every page in every aobj that is paged-out to a range of swslots. 1185 * 1186 * => nothing should be locked. 1187 * => returns true if pagein was aborted due to lack of memory. 1188 */ 1189 1190 bool 1191 uao_swap_off(int startslot, int endslot) 1192 { 1193 struct uvm_aobj *aobj; 1194 1195 /* 1196 * Walk the list of all anonymous UVM objects. Grab the first. 1197 */ 1198 mutex_enter(&uao_list_lock); 1199 if ((aobj = LIST_FIRST(&uao_list)) == NULL) { 1200 mutex_exit(&uao_list_lock); 1201 return false; 1202 } 1203 uao_reference(&aobj->u_obj); 1204 1205 do { 1206 struct uvm_aobj *nextaobj; 1207 bool rv; 1208 1209 /* 1210 * Prefetch the next object and immediately hold a reference 1211 * on it, so neither the current nor the next entry could 1212 * disappear while we are iterating. 1213 */ 1214 if ((nextaobj = LIST_NEXT(aobj, u_list)) != NULL) { 1215 uao_reference(&nextaobj->u_obj); 1216 } 1217 mutex_exit(&uao_list_lock); 1218 1219 /* 1220 * Page in all pages in the swap slot range. 1221 */ 1222 mutex_enter(aobj->u_obj.vmobjlock); 1223 rv = uao_pagein(aobj, startslot, endslot); 1224 mutex_exit(aobj->u_obj.vmobjlock); 1225 1226 /* Drop the reference of the current object. */ 1227 uao_detach(&aobj->u_obj); 1228 if (rv) { 1229 if (nextaobj) { 1230 uao_detach(&nextaobj->u_obj); 1231 } 1232 return rv; 1233 } 1234 1235 aobj = nextaobj; 1236 mutex_enter(&uao_list_lock); 1237 } while (aobj); 1238 1239 mutex_exit(&uao_list_lock); 1240 return false; 1241 } 1242 1243 /* 1244 * page in any pages from aobj in the given range. 1245 * 1246 * => aobj must be locked and is returned locked. 1247 * => returns true if pagein was aborted due to lack of memory. 1248 */ 1249 static bool 1250 uao_pagein(struct uvm_aobj *aobj, int startslot, int endslot) 1251 { 1252 bool rv; 1253 1254 if (UAO_USES_SWHASH(aobj)) { 1255 struct uao_swhash_elt *elt; 1256 int buck; 1257 1258 restart: 1259 for (buck = aobj->u_swhashmask; buck >= 0; buck--) { 1260 for (elt = LIST_FIRST(&aobj->u_swhash[buck]); 1261 elt != NULL; 1262 elt = LIST_NEXT(elt, list)) { 1263 int i; 1264 1265 for (i = 0; i < UAO_SWHASH_CLUSTER_SIZE; i++) { 1266 int slot = elt->slots[i]; 1267 1268 /* 1269 * if the slot isn't in range, skip it. 1270 */ 1271 1272 if (slot < startslot || 1273 slot >= endslot) { 1274 continue; 1275 } 1276 1277 /* 1278 * process the page, 1279 * the start over on this object 1280 * since the swhash elt 1281 * may have been freed. 1282 */ 1283 1284 rv = uao_pagein_page(aobj, 1285 UAO_SWHASH_ELT_PAGEIDX_BASE(elt) + i); 1286 if (rv) { 1287 return rv; 1288 } 1289 goto restart; 1290 } 1291 } 1292 } 1293 } else { 1294 int i; 1295 1296 for (i = 0; i < aobj->u_pages; i++) { 1297 int slot = aobj->u_swslots[i]; 1298 1299 /* 1300 * if the slot isn't in range, skip it 1301 */ 1302 1303 if (slot < startslot || slot >= endslot) { 1304 continue; 1305 } 1306 1307 /* 1308 * process the page. 1309 */ 1310 1311 rv = uao_pagein_page(aobj, i); 1312 if (rv) { 1313 return rv; 1314 } 1315 } 1316 } 1317 1318 return false; 1319 } 1320 1321 /* 1322 * uao_pagein_page: page in a single page from an anonymous UVM object. 1323 * 1324 * => Returns true if pagein was aborted due to lack of memory. 1325 * => Object must be locked and is returned locked. 1326 */ 1327 1328 static bool 1329 uao_pagein_page(struct uvm_aobj *aobj, int pageidx) 1330 { 1331 struct uvm_object *uobj = &aobj->u_obj; 1332 struct vm_page *pg; 1333 int rv, npages; 1334 1335 pg = NULL; 1336 npages = 1; 1337 1338 KASSERT(mutex_owned(uobj->vmobjlock)); 1339 rv = uao_get(uobj, pageidx << PAGE_SHIFT, &pg, &npages, 1340 0, VM_PROT_READ | VM_PROT_WRITE, 0, PGO_SYNCIO); 1341 1342 /* 1343 * relock and finish up. 1344 */ 1345 1346 mutex_enter(uobj->vmobjlock); 1347 switch (rv) { 1348 case 0: 1349 break; 1350 1351 case EIO: 1352 case ERESTART: 1353 1354 /* 1355 * nothing more to do on errors. 1356 * ERESTART can only mean that the anon was freed, 1357 * so again there's nothing to do. 1358 */ 1359 1360 return false; 1361 1362 default: 1363 return true; 1364 } 1365 1366 /* 1367 * ok, we've got the page now. 1368 * mark it as dirty, clear its swslot and un-busy it. 1369 */ 1370 uao_dropswap(&aobj->u_obj, pageidx); 1371 1372 /* 1373 * make sure it's on a page queue. 1374 */ 1375 mutex_enter(&uvm_pageqlock); 1376 if (pg->wire_count == 0) 1377 uvm_pageenqueue(pg); 1378 mutex_exit(&uvm_pageqlock); 1379 1380 if (pg->flags & PG_WANTED) { 1381 wakeup(pg); 1382 } 1383 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_CLEAN|PG_FAKE); 1384 UVM_PAGE_OWN(pg, NULL); 1385 1386 return false; 1387 } 1388 1389 /* 1390 * uao_dropswap_range: drop swapslots in the range. 1391 * 1392 * => aobj must be locked and is returned locked. 1393 * => start is inclusive. end is exclusive. 1394 */ 1395 1396 void 1397 uao_dropswap_range(struct uvm_object *uobj, voff_t start, voff_t end) 1398 { 1399 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 1400 int swpgonlydelta = 0; 1401 1402 KASSERT(mutex_owned(uobj->vmobjlock)); 1403 1404 if (end == 0) { 1405 end = INT64_MAX; 1406 } 1407 1408 if (UAO_USES_SWHASH(aobj)) { 1409 int i, hashbuckets = aobj->u_swhashmask + 1; 1410 voff_t taghi; 1411 voff_t taglo; 1412 1413 taglo = UAO_SWHASH_ELT_TAG(start); 1414 taghi = UAO_SWHASH_ELT_TAG(end); 1415 1416 for (i = 0; i < hashbuckets; i++) { 1417 struct uao_swhash_elt *elt, *next; 1418 1419 for (elt = LIST_FIRST(&aobj->u_swhash[i]); 1420 elt != NULL; 1421 elt = next) { 1422 int startidx, endidx; 1423 int j; 1424 1425 next = LIST_NEXT(elt, list); 1426 1427 if (elt->tag < taglo || taghi < elt->tag) { 1428 continue; 1429 } 1430 1431 if (elt->tag == taglo) { 1432 startidx = 1433 UAO_SWHASH_ELT_PAGESLOT_IDX(start); 1434 } else { 1435 startidx = 0; 1436 } 1437 1438 if (elt->tag == taghi) { 1439 endidx = 1440 UAO_SWHASH_ELT_PAGESLOT_IDX(end); 1441 } else { 1442 endidx = UAO_SWHASH_CLUSTER_SIZE; 1443 } 1444 1445 for (j = startidx; j < endidx; j++) { 1446 int slot = elt->slots[j]; 1447 1448 KASSERT(uvm_pagelookup(&aobj->u_obj, 1449 (UAO_SWHASH_ELT_PAGEIDX_BASE(elt) 1450 + j) << PAGE_SHIFT) == NULL); 1451 if (slot > 0) { 1452 uvm_swap_free(slot, 1); 1453 swpgonlydelta++; 1454 KASSERT(elt->count > 0); 1455 elt->slots[j] = 0; 1456 elt->count--; 1457 } 1458 } 1459 1460 if (elt->count == 0) { 1461 LIST_REMOVE(elt, list); 1462 pool_put(&uao_swhash_elt_pool, elt); 1463 } 1464 } 1465 } 1466 } else { 1467 int i; 1468 1469 if (aobj->u_pages < end) { 1470 end = aobj->u_pages; 1471 } 1472 for (i = start; i < end; i++) { 1473 int slot = aobj->u_swslots[i]; 1474 1475 if (slot > 0) { 1476 uvm_swap_free(slot, 1); 1477 swpgonlydelta++; 1478 } 1479 } 1480 } 1481 1482 /* 1483 * adjust the counter of pages only in swap for all 1484 * the swap slots we've freed. 1485 */ 1486 1487 if (swpgonlydelta > 0) { 1488 mutex_enter(&uvm_swap_data_lock); 1489 KASSERT(uvmexp.swpgonly >= swpgonlydelta); 1490 uvmexp.swpgonly -= swpgonlydelta; 1491 mutex_exit(&uvm_swap_data_lock); 1492 } 1493 } 1494 1495 #endif /* defined(VMSWAP) */ 1496