1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 70 /* 71 * Page fault handling module. 72 */ 73 74 #include <sys/cdefs.h> 75 __FBSDID("$FreeBSD$"); 76 77 #include "opt_vm.h" 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/lock.h> 83 #include <sys/mutex.h> 84 #include <sys/proc.h> 85 #include <sys/resourcevar.h> 86 #include <sys/sysctl.h> 87 #include <sys/vmmeter.h> 88 #include <sys/vnode.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_object.h> 95 #include <vm/vm_page.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_kern.h> 98 #include <vm/vm_pager.h> 99 #include <vm/vm_extern.h> 100 101 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */ 102 103 #define PFBAK 4 104 #define PFFOR 4 105 #define PAGEORDER_SIZE (PFBAK+PFFOR) 106 107 static int prefault_pageorder[] = { 108 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 109 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 110 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 111 -4 * PAGE_SIZE, 4 * PAGE_SIZE 112 }; 113 114 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 115 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 116 117 #define VM_FAULT_READ_AHEAD 8 118 #define VM_FAULT_READ_BEHIND 7 119 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) 120 121 struct faultstate { 122 vm_page_t m; 123 vm_object_t object; 124 vm_pindex_t pindex; 125 vm_page_t first_m; 126 vm_object_t first_object; 127 vm_pindex_t first_pindex; 128 vm_map_t map; 129 vm_map_entry_t entry; 130 int lookup_still_valid; 131 struct vnode *vp; 132 int vfslocked; 133 }; 134 135 static inline void 136 release_page(struct faultstate *fs) 137 { 138 139 vm_page_wakeup(fs->m); 140 vm_page_lock(fs->m); 141 vm_page_deactivate(fs->m); 142 vm_page_unlock(fs->m); 143 fs->m = NULL; 144 } 145 146 static inline void 147 unlock_map(struct faultstate *fs) 148 { 149 150 if (fs->lookup_still_valid) { 151 vm_map_lookup_done(fs->map, fs->entry); 152 fs->lookup_still_valid = FALSE; 153 } 154 } 155 156 static void 157 unlock_and_deallocate(struct faultstate *fs) 158 { 159 160 vm_object_pip_wakeup(fs->object); 161 VM_OBJECT_UNLOCK(fs->object); 162 if (fs->object != fs->first_object) { 163 VM_OBJECT_LOCK(fs->first_object); 164 vm_page_lock(fs->first_m); 165 vm_page_free(fs->first_m); 166 vm_page_unlock(fs->first_m); 167 vm_object_pip_wakeup(fs->first_object); 168 VM_OBJECT_UNLOCK(fs->first_object); 169 fs->first_m = NULL; 170 } 171 vm_object_deallocate(fs->first_object); 172 unlock_map(fs); 173 if (fs->vp != NULL) { 174 vput(fs->vp); 175 fs->vp = NULL; 176 } 177 VFS_UNLOCK_GIANT(fs->vfslocked); 178 fs->vfslocked = 0; 179 } 180 181 /* 182 * TRYPAGER - used by vm_fault to calculate whether the pager for the 183 * current object *might* contain the page. 184 * 185 * default objects are zero-fill, there is no real pager. 186 */ 187 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 188 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 189 190 /* 191 * vm_fault: 192 * 193 * Handle a page fault occurring at the given address, 194 * requiring the given permissions, in the map specified. 195 * If successful, the page is inserted into the 196 * associated physical map. 197 * 198 * NOTE: the given address should be truncated to the 199 * proper page address. 200 * 201 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 202 * a standard error specifying why the fault is fatal is returned. 203 * 204 * 205 * The map in question must be referenced, and remains so. 206 * Caller may hold no locks. 207 */ 208 int 209 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 210 int fault_flags) 211 { 212 vm_prot_t prot; 213 int is_first_object_locked, result; 214 boolean_t growstack, wired; 215 int map_generation; 216 vm_object_t next_object; 217 vm_page_t marray[VM_FAULT_READ], mt, mt_prev; 218 int hardfault; 219 int faultcount, ahead, behind, alloc_req; 220 struct faultstate fs; 221 struct vnode *vp; 222 int locked, error; 223 224 hardfault = 0; 225 growstack = TRUE; 226 PCPU_INC(cnt.v_vm_faults); 227 fs.vp = NULL; 228 fs.vfslocked = 0; 229 faultcount = behind = 0; 230 231 RetryFault:; 232 233 /* 234 * Find the backing store object and offset into it to begin the 235 * search. 236 */ 237 fs.map = map; 238 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 239 &fs.first_object, &fs.first_pindex, &prot, &wired); 240 if (result != KERN_SUCCESS) { 241 if (growstack && result == KERN_INVALID_ADDRESS && 242 map != kernel_map) { 243 result = vm_map_growstack(curproc, vaddr); 244 if (result != KERN_SUCCESS) 245 return (KERN_FAILURE); 246 growstack = FALSE; 247 goto RetryFault; 248 } 249 return (result); 250 } 251 252 map_generation = fs.map->timestamp; 253 254 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 255 panic("vm_fault: fault on nofault entry, addr: %lx", 256 (u_long)vaddr); 257 } 258 259 /* 260 * Make a reference to this object to prevent its disposal while we 261 * are messing with it. Once we have the reference, the map is free 262 * to be diddled. Since objects reference their shadows (and copies), 263 * they will stay around as well. 264 * 265 * Bump the paging-in-progress count to prevent size changes (e.g. 266 * truncation operations) during I/O. This must be done after 267 * obtaining the vnode lock in order to avoid possible deadlocks. 268 */ 269 VM_OBJECT_LOCK(fs.first_object); 270 vm_object_reference_locked(fs.first_object); 271 vm_object_pip_add(fs.first_object, 1); 272 273 fs.lookup_still_valid = TRUE; 274 275 if (wired) 276 fault_type = prot | (fault_type & VM_PROT_COPY); 277 278 fs.first_m = NULL; 279 280 /* 281 * Search for the page at object/offset. 282 */ 283 fs.object = fs.first_object; 284 fs.pindex = fs.first_pindex; 285 while (TRUE) { 286 /* 287 * If the object is dead, we stop here 288 */ 289 if (fs.object->flags & OBJ_DEAD) { 290 unlock_and_deallocate(&fs); 291 return (KERN_PROTECTION_FAILURE); 292 } 293 294 /* 295 * See if page is resident 296 */ 297 fs.m = vm_page_lookup(fs.object, fs.pindex); 298 if (fs.m != NULL) { 299 /* 300 * check for page-based copy on write. 301 * We check fs.object == fs.first_object so 302 * as to ensure the legacy COW mechanism is 303 * used when the page in question is part of 304 * a shadow object. Otherwise, vm_page_cowfault() 305 * removes the page from the backing object, 306 * which is not what we want. 307 */ 308 vm_page_lock(fs.m); 309 if ((fs.m->cow) && 310 (fault_type & VM_PROT_WRITE) && 311 (fs.object == fs.first_object)) { 312 vm_page_cowfault(fs.m); 313 unlock_and_deallocate(&fs); 314 goto RetryFault; 315 } 316 317 /* 318 * Wait/Retry if the page is busy. We have to do this 319 * if the page is busy via either VPO_BUSY or 320 * vm_page_t->busy because the vm_pager may be using 321 * vm_page_t->busy for pageouts ( and even pageins if 322 * it is the vnode pager ), and we could end up trying 323 * to pagein and pageout the same page simultaneously. 324 * 325 * We can theoretically allow the busy case on a read 326 * fault if the page is marked valid, but since such 327 * pages are typically already pmap'd, putting that 328 * special case in might be more effort then it is 329 * worth. We cannot under any circumstances mess 330 * around with a vm_page_t->busy page except, perhaps, 331 * to pmap it. 332 */ 333 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) { 334 /* 335 * Reference the page before unlocking and 336 * sleeping so that the page daemon is less 337 * likely to reclaim it. 338 */ 339 vm_page_lock_queues(); 340 vm_page_flag_set(fs.m, PG_REFERENCED); 341 vm_page_unlock_queues(); 342 vm_page_unlock(fs.m); 343 if (fs.object != fs.first_object) { 344 if (!VM_OBJECT_TRYLOCK( 345 fs.first_object)) { 346 VM_OBJECT_UNLOCK(fs.object); 347 VM_OBJECT_LOCK(fs.first_object); 348 VM_OBJECT_LOCK(fs.object); 349 } 350 vm_page_lock(fs.first_m); 351 vm_page_free(fs.first_m); 352 vm_page_unlock(fs.first_m); 353 vm_object_pip_wakeup(fs.first_object); 354 VM_OBJECT_UNLOCK(fs.first_object); 355 fs.first_m = NULL; 356 } 357 unlock_map(&fs); 358 if (fs.m == vm_page_lookup(fs.object, 359 fs.pindex)) { 360 vm_page_sleep_if_busy(fs.m, TRUE, 361 "vmpfw"); 362 } 363 vm_object_pip_wakeup(fs.object); 364 VM_OBJECT_UNLOCK(fs.object); 365 PCPU_INC(cnt.v_intrans); 366 vm_object_deallocate(fs.first_object); 367 goto RetryFault; 368 } 369 vm_pageq_remove(fs.m); 370 vm_page_unlock(fs.m); 371 372 /* 373 * Mark page busy for other processes, and the 374 * pagedaemon. If it still isn't completely valid 375 * (readable), jump to readrest, else break-out ( we 376 * found the page ). 377 */ 378 vm_page_busy(fs.m); 379 if (fs.m->valid != VM_PAGE_BITS_ALL && 380 fs.m->object != kernel_object && fs.m->object != kmem_object) { 381 goto readrest; 382 } 383 384 break; 385 } 386 387 /* 388 * Page is not resident, If this is the search termination 389 * or the pager might contain the page, allocate a new page. 390 */ 391 if (TRYPAGER || fs.object == fs.first_object) { 392 if (fs.pindex >= fs.object->size) { 393 unlock_and_deallocate(&fs); 394 return (KERN_PROTECTION_FAILURE); 395 } 396 397 /* 398 * Allocate a new page for this object/offset pair. 399 * 400 * Unlocked read of the p_flag is harmless. At 401 * worst, the P_KILLED might be not observed 402 * there, and allocation can fail, causing 403 * restart and new reading of the p_flag. 404 */ 405 fs.m = NULL; 406 if (!vm_page_count_severe() || P_KILLED(curproc)) { 407 #if VM_NRESERVLEVEL > 0 408 if ((fs.object->flags & OBJ_COLORED) == 0) { 409 fs.object->flags |= OBJ_COLORED; 410 fs.object->pg_color = atop(vaddr) - 411 fs.pindex; 412 } 413 #endif 414 alloc_req = P_KILLED(curproc) ? 415 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 416 if (fs.object->type != OBJT_VNODE && 417 fs.object->backing_object == NULL) 418 alloc_req |= VM_ALLOC_ZERO; 419 fs.m = vm_page_alloc(fs.object, fs.pindex, 420 alloc_req); 421 } 422 if (fs.m == NULL) { 423 unlock_and_deallocate(&fs); 424 VM_WAITPFAULT; 425 goto RetryFault; 426 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 427 break; 428 } 429 430 readrest: 431 /* 432 * We have found a valid page or we have allocated a new page. 433 * The page thus may not be valid or may not be entirely 434 * valid. 435 * 436 * Attempt to fault-in the page if there is a chance that the 437 * pager has it, and potentially fault in additional pages 438 * at the same time. 439 */ 440 if (TRYPAGER) { 441 int rv; 442 int reqpage = 0; 443 u_char behavior = vm_map_entry_behavior(fs.entry); 444 445 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 446 P_KILLED(curproc)) { 447 ahead = 0; 448 behind = 0; 449 } else { 450 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 451 if (behind > VM_FAULT_READ_BEHIND) 452 behind = VM_FAULT_READ_BEHIND; 453 454 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 455 if (ahead > VM_FAULT_READ_AHEAD) 456 ahead = VM_FAULT_READ_AHEAD; 457 } 458 is_first_object_locked = FALSE; 459 if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 460 (behavior != MAP_ENTRY_BEHAV_RANDOM && 461 fs.pindex >= fs.entry->lastr && 462 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) && 463 (fs.first_object == fs.object || 464 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) && 465 fs.first_object->type != OBJT_DEVICE && 466 fs.first_object->type != OBJT_PHYS && 467 fs.first_object->type != OBJT_SG) { 468 vm_pindex_t firstpindex; 469 470 if (fs.first_pindex < 2 * VM_FAULT_READ) 471 firstpindex = 0; 472 else 473 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 474 mt = fs.first_object != fs.object ? 475 fs.first_m : fs.m; 476 KASSERT(mt != NULL, ("vm_fault: missing mt")); 477 KASSERT((mt->oflags & VPO_BUSY) != 0, 478 ("vm_fault: mt %p not busy", mt)); 479 mt_prev = vm_page_prev(mt); 480 481 /* 482 * note: partially valid pages cannot be 483 * included in the lookahead - NFS piecemeal 484 * writes will barf on it badly. 485 */ 486 while ((mt = mt_prev) != NULL && 487 mt->pindex >= firstpindex && 488 mt->valid == VM_PAGE_BITS_ALL) { 489 mt_prev = vm_page_prev(mt); 490 if (mt->busy || 491 (mt->oflags & VPO_BUSY)) 492 continue; 493 vm_page_lock(mt); 494 if (mt->hold_count || 495 mt->wire_count) { 496 vm_page_unlock(mt); 497 continue; 498 } 499 pmap_remove_all(mt); 500 if (mt->dirty != 0) 501 vm_page_deactivate(mt); 502 else 503 vm_page_cache(mt); 504 vm_page_unlock(mt); 505 } 506 ahead += behind; 507 behind = 0; 508 } 509 if (is_first_object_locked) 510 VM_OBJECT_UNLOCK(fs.first_object); 511 512 /* 513 * Call the pager to retrieve the data, if any, after 514 * releasing the lock on the map. We hold a ref on 515 * fs.object and the pages are VPO_BUSY'd. 516 */ 517 unlock_map(&fs); 518 519 vnode_lock: 520 if (fs.object->type == OBJT_VNODE) { 521 vp = fs.object->handle; 522 if (vp == fs.vp) 523 goto vnode_locked; 524 else if (fs.vp != NULL) { 525 vput(fs.vp); 526 fs.vp = NULL; 527 } 528 locked = VOP_ISLOCKED(vp); 529 530 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 531 fs.vfslocked = 1; 532 if (!mtx_trylock(&Giant)) { 533 VM_OBJECT_UNLOCK(fs.object); 534 mtx_lock(&Giant); 535 VM_OBJECT_LOCK(fs.object); 536 goto vnode_lock; 537 } 538 } 539 if (locked != LK_EXCLUSIVE) 540 locked = LK_SHARED; 541 /* Do not sleep for vnode lock while fs.m is busy */ 542 error = vget(vp, locked | LK_CANRECURSE | 543 LK_NOWAIT, curthread); 544 if (error != 0) { 545 int vfslocked; 546 547 vfslocked = fs.vfslocked; 548 fs.vfslocked = 0; /* Keep Giant */ 549 vhold(vp); 550 release_page(&fs); 551 unlock_and_deallocate(&fs); 552 error = vget(vp, locked | LK_RETRY | 553 LK_CANRECURSE, curthread); 554 vdrop(vp); 555 fs.vp = vp; 556 fs.vfslocked = vfslocked; 557 KASSERT(error == 0, 558 ("vm_fault: vget failed")); 559 goto RetryFault; 560 } 561 fs.vp = vp; 562 } 563 vnode_locked: 564 KASSERT(fs.vp == NULL || !fs.map->system_map, 565 ("vm_fault: vnode-backed object mapped by system map")); 566 567 /* 568 * now we find out if any other pages should be paged 569 * in at this time this routine checks to see if the 570 * pages surrounding this fault reside in the same 571 * object as the page for this fault. If they do, 572 * then they are faulted in also into the object. The 573 * array "marray" returned contains an array of 574 * vm_page_t structs where one of them is the 575 * vm_page_t passed to the routine. The reqpage 576 * return value is the index into the marray for the 577 * vm_page_t passed to the routine. 578 * 579 * fs.m plus the additional pages are VPO_BUSY'd. 580 */ 581 faultcount = vm_fault_additional_pages( 582 fs.m, behind, ahead, marray, &reqpage); 583 584 rv = faultcount ? 585 vm_pager_get_pages(fs.object, marray, faultcount, 586 reqpage) : VM_PAGER_FAIL; 587 588 if (rv == VM_PAGER_OK) { 589 /* 590 * Found the page. Leave it busy while we play 591 * with it. 592 */ 593 594 /* 595 * Relookup in case pager changed page. Pager 596 * is responsible for disposition of old page 597 * if moved. 598 */ 599 fs.m = vm_page_lookup(fs.object, fs.pindex); 600 if (!fs.m) { 601 unlock_and_deallocate(&fs); 602 goto RetryFault; 603 } 604 605 hardfault++; 606 break; /* break to PAGE HAS BEEN FOUND */ 607 } 608 /* 609 * Remove the bogus page (which does not exist at this 610 * object/offset); before doing so, we must get back 611 * our object lock to preserve our invariant. 612 * 613 * Also wake up any other process that may want to bring 614 * in this page. 615 * 616 * If this is the top-level object, we must leave the 617 * busy page to prevent another process from rushing 618 * past us, and inserting the page in that object at 619 * the same time that we are. 620 */ 621 if (rv == VM_PAGER_ERROR) 622 printf("vm_fault: pager read error, pid %d (%s)\n", 623 curproc->p_pid, curproc->p_comm); 624 /* 625 * Data outside the range of the pager or an I/O error 626 */ 627 /* 628 * XXX - the check for kernel_map is a kludge to work 629 * around having the machine panic on a kernel space 630 * fault w/ I/O error. 631 */ 632 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 633 (rv == VM_PAGER_BAD)) { 634 vm_page_lock(fs.m); 635 vm_page_free(fs.m); 636 vm_page_unlock(fs.m); 637 fs.m = NULL; 638 unlock_and_deallocate(&fs); 639 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 640 } 641 if (fs.object != fs.first_object) { 642 vm_page_lock(fs.m); 643 vm_page_free(fs.m); 644 vm_page_unlock(fs.m); 645 fs.m = NULL; 646 /* 647 * XXX - we cannot just fall out at this 648 * point, m has been freed and is invalid! 649 */ 650 } 651 } 652 653 /* 654 * We get here if the object has default pager (or unwiring) 655 * or the pager doesn't have the page. 656 */ 657 if (fs.object == fs.first_object) 658 fs.first_m = fs.m; 659 660 /* 661 * Move on to the next object. Lock the next object before 662 * unlocking the current one. 663 */ 664 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 665 next_object = fs.object->backing_object; 666 if (next_object == NULL) { 667 /* 668 * If there's no object left, fill the page in the top 669 * object with zeros. 670 */ 671 if (fs.object != fs.first_object) { 672 vm_object_pip_wakeup(fs.object); 673 VM_OBJECT_UNLOCK(fs.object); 674 675 fs.object = fs.first_object; 676 fs.pindex = fs.first_pindex; 677 fs.m = fs.first_m; 678 VM_OBJECT_LOCK(fs.object); 679 } 680 fs.first_m = NULL; 681 682 /* 683 * Zero the page if necessary and mark it valid. 684 */ 685 if ((fs.m->flags & PG_ZERO) == 0) { 686 pmap_zero_page(fs.m); 687 } else { 688 PCPU_INC(cnt.v_ozfod); 689 } 690 PCPU_INC(cnt.v_zfod); 691 fs.m->valid = VM_PAGE_BITS_ALL; 692 break; /* break to PAGE HAS BEEN FOUND */ 693 } else { 694 KASSERT(fs.object != next_object, 695 ("object loop %p", next_object)); 696 VM_OBJECT_LOCK(next_object); 697 vm_object_pip_add(next_object, 1); 698 if (fs.object != fs.first_object) 699 vm_object_pip_wakeup(fs.object); 700 VM_OBJECT_UNLOCK(fs.object); 701 fs.object = next_object; 702 } 703 } 704 705 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 706 ("vm_fault: not busy after main loop")); 707 708 /* 709 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 710 * is held.] 711 */ 712 713 /* 714 * If the page is being written, but isn't already owned by the 715 * top-level object, we have to copy it into a new page owned by the 716 * top-level object. 717 */ 718 if (fs.object != fs.first_object) { 719 /* 720 * We only really need to copy if we want to write it. 721 */ 722 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 723 /* 724 * This allows pages to be virtually copied from a 725 * backing_object into the first_object, where the 726 * backing object has no other refs to it, and cannot 727 * gain any more refs. Instead of a bcopy, we just 728 * move the page from the backing object to the 729 * first object. Note that we must mark the page 730 * dirty in the first object so that it will go out 731 * to swap when needed. 732 */ 733 is_first_object_locked = FALSE; 734 if ( 735 /* 736 * Only one shadow object 737 */ 738 (fs.object->shadow_count == 1) && 739 /* 740 * No COW refs, except us 741 */ 742 (fs.object->ref_count == 1) && 743 /* 744 * No one else can look this object up 745 */ 746 (fs.object->handle == NULL) && 747 /* 748 * No other ways to look the object up 749 */ 750 ((fs.object->type == OBJT_DEFAULT) || 751 (fs.object->type == OBJT_SWAP)) && 752 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 753 /* 754 * We don't chase down the shadow chain 755 */ 756 fs.object == fs.first_object->backing_object) { 757 /* 758 * get rid of the unnecessary page 759 */ 760 vm_page_lock(fs.first_m); 761 vm_page_free(fs.first_m); 762 vm_page_unlock(fs.first_m); 763 /* 764 * grab the page and put it into the 765 * process'es object. The page is 766 * automatically made dirty. 767 */ 768 vm_page_lock(fs.m); 769 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 770 vm_page_unlock(fs.m); 771 vm_page_busy(fs.m); 772 fs.first_m = fs.m; 773 fs.m = NULL; 774 PCPU_INC(cnt.v_cow_optim); 775 } else { 776 /* 777 * Oh, well, lets copy it. 778 */ 779 pmap_copy_page(fs.m, fs.first_m); 780 fs.first_m->valid = VM_PAGE_BITS_ALL; 781 if (wired && (fault_flags & 782 VM_FAULT_CHANGE_WIRING) == 0) { 783 vm_page_lock(fs.first_m); 784 vm_page_wire(fs.first_m); 785 vm_page_unlock(fs.first_m); 786 787 vm_page_lock(fs.m); 788 vm_page_unwire(fs.m, FALSE); 789 vm_page_unlock(fs.m); 790 } 791 /* 792 * We no longer need the old page or object. 793 */ 794 release_page(&fs); 795 } 796 /* 797 * fs.object != fs.first_object due to above 798 * conditional 799 */ 800 vm_object_pip_wakeup(fs.object); 801 VM_OBJECT_UNLOCK(fs.object); 802 /* 803 * Only use the new page below... 804 */ 805 fs.object = fs.first_object; 806 fs.pindex = fs.first_pindex; 807 fs.m = fs.first_m; 808 if (!is_first_object_locked) 809 VM_OBJECT_LOCK(fs.object); 810 PCPU_INC(cnt.v_cow_faults); 811 } else { 812 prot &= ~VM_PROT_WRITE; 813 } 814 } 815 816 /* 817 * We must verify that the maps have not changed since our last 818 * lookup. 819 */ 820 if (!fs.lookup_still_valid) { 821 vm_object_t retry_object; 822 vm_pindex_t retry_pindex; 823 vm_prot_t retry_prot; 824 825 if (!vm_map_trylock_read(fs.map)) { 826 release_page(&fs); 827 unlock_and_deallocate(&fs); 828 goto RetryFault; 829 } 830 fs.lookup_still_valid = TRUE; 831 if (fs.map->timestamp != map_generation) { 832 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 833 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 834 835 /* 836 * If we don't need the page any longer, put it on the inactive 837 * list (the easiest thing to do here). If no one needs it, 838 * pageout will grab it eventually. 839 */ 840 if (result != KERN_SUCCESS) { 841 release_page(&fs); 842 unlock_and_deallocate(&fs); 843 844 /* 845 * If retry of map lookup would have blocked then 846 * retry fault from start. 847 */ 848 if (result == KERN_FAILURE) 849 goto RetryFault; 850 return (result); 851 } 852 if ((retry_object != fs.first_object) || 853 (retry_pindex != fs.first_pindex)) { 854 release_page(&fs); 855 unlock_and_deallocate(&fs); 856 goto RetryFault; 857 } 858 859 /* 860 * Check whether the protection has changed or the object has 861 * been copied while we left the map unlocked. Changing from 862 * read to write permission is OK - we leave the page 863 * write-protected, and catch the write fault. Changing from 864 * write to read permission means that we can't mark the page 865 * write-enabled after all. 866 */ 867 prot &= retry_prot; 868 } 869 } 870 /* 871 * If the page was filled by a pager, update the map entry's 872 * last read offset. Since the pager does not return the 873 * actual set of pages that it read, this update is based on 874 * the requested set. Typically, the requested and actual 875 * sets are the same. 876 * 877 * XXX The following assignment modifies the map 878 * without holding a write lock on it. 879 */ 880 if (hardfault) 881 fs.entry->lastr = fs.pindex + faultcount - behind; 882 883 if (prot & VM_PROT_WRITE) { 884 vm_object_set_writeable_dirty(fs.object); 885 886 /* 887 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 888 * if the page is already dirty to prevent data written with 889 * the expectation of being synced from not being synced. 890 * Likewise if this entry does not request NOSYNC then make 891 * sure the page isn't marked NOSYNC. Applications sharing 892 * data should use the same flags to avoid ping ponging. 893 */ 894 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 895 if (fs.m->dirty == 0) 896 fs.m->oflags |= VPO_NOSYNC; 897 } else { 898 fs.m->oflags &= ~VPO_NOSYNC; 899 } 900 901 /* 902 * If the fault is a write, we know that this page is being 903 * written NOW so dirty it explicitly to save on 904 * pmap_is_modified() calls later. 905 * 906 * Also tell the backing pager, if any, that it should remove 907 * any swap backing since the page is now dirty. 908 */ 909 if ((fault_type & VM_PROT_WRITE) != 0 && 910 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) { 911 vm_page_dirty(fs.m); 912 vm_pager_page_unswapped(fs.m); 913 } 914 } 915 916 /* 917 * Page had better still be busy 918 */ 919 KASSERT(fs.m->oflags & VPO_BUSY, 920 ("vm_fault: page %p not busy!", fs.m)); 921 /* 922 * Page must be completely valid or it is not fit to 923 * map into user space. vm_pager_get_pages() ensures this. 924 */ 925 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 926 ("vm_fault: page %p partially invalid", fs.m)); 927 VM_OBJECT_UNLOCK(fs.object); 928 929 /* 930 * Put this page into the physical map. We had to do the unlock above 931 * because pmap_enter() may sleep. We don't put the page 932 * back on the active queue until later so that the pageout daemon 933 * won't find it (yet). 934 */ 935 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 936 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 937 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 938 VM_OBJECT_LOCK(fs.object); 939 vm_page_lock(fs.m); 940 941 /* 942 * If the page is not wired down, then put it where the pageout daemon 943 * can find it. 944 */ 945 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 946 if (wired) 947 vm_page_wire(fs.m); 948 else 949 vm_page_unwire(fs.m, 1); 950 } else 951 vm_page_activate(fs.m); 952 vm_page_unlock(fs.m); 953 vm_page_wakeup(fs.m); 954 955 /* 956 * Unlock everything, and return 957 */ 958 unlock_and_deallocate(&fs); 959 if (hardfault) 960 curthread->td_ru.ru_majflt++; 961 else 962 curthread->td_ru.ru_minflt++; 963 964 return (KERN_SUCCESS); 965 } 966 967 /* 968 * vm_fault_prefault provides a quick way of clustering 969 * pagefaults into a processes address space. It is a "cousin" 970 * of vm_map_pmap_enter, except it runs at page fault time instead 971 * of mmap time. 972 */ 973 static void 974 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 975 { 976 int i; 977 vm_offset_t addr, starta; 978 vm_pindex_t pindex; 979 vm_page_t m; 980 vm_object_t object; 981 982 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 983 return; 984 985 object = entry->object.vm_object; 986 987 starta = addra - PFBAK * PAGE_SIZE; 988 if (starta < entry->start) { 989 starta = entry->start; 990 } else if (starta > addra) { 991 starta = 0; 992 } 993 994 for (i = 0; i < PAGEORDER_SIZE; i++) { 995 vm_object_t backing_object, lobject; 996 997 addr = addra + prefault_pageorder[i]; 998 if (addr > addra + (PFFOR * PAGE_SIZE)) 999 addr = 0; 1000 1001 if (addr < starta || addr >= entry->end) 1002 continue; 1003 1004 if (!pmap_is_prefaultable(pmap, addr)) 1005 continue; 1006 1007 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1008 lobject = object; 1009 VM_OBJECT_LOCK(lobject); 1010 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1011 lobject->type == OBJT_DEFAULT && 1012 (backing_object = lobject->backing_object) != NULL) { 1013 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1014 0, ("vm_fault_prefault: unaligned object offset")); 1015 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1016 VM_OBJECT_LOCK(backing_object); 1017 VM_OBJECT_UNLOCK(lobject); 1018 lobject = backing_object; 1019 } 1020 /* 1021 * give-up when a page is not in memory 1022 */ 1023 if (m == NULL) { 1024 VM_OBJECT_UNLOCK(lobject); 1025 break; 1026 } 1027 if (m->valid == VM_PAGE_BITS_ALL && 1028 (m->flags & PG_FICTITIOUS) == 0) 1029 pmap_enter_quick(pmap, addr, m, entry->protection); 1030 VM_OBJECT_UNLOCK(lobject); 1031 } 1032 } 1033 1034 /* 1035 * vm_fault_quick: 1036 * 1037 * Ensure that the requested virtual address, which may be in userland, 1038 * is valid. Fault-in the page if necessary. Return -1 on failure. 1039 */ 1040 int 1041 vm_fault_quick(caddr_t v, int prot) 1042 { 1043 int r; 1044 1045 if (prot & VM_PROT_WRITE) 1046 r = subyte(v, fubyte(v)); 1047 else 1048 r = fubyte(v); 1049 return(r); 1050 } 1051 1052 /* 1053 * vm_fault_wire: 1054 * 1055 * Wire down a range of virtual addresses in a map. 1056 */ 1057 int 1058 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1059 boolean_t fictitious) 1060 { 1061 vm_offset_t va; 1062 int rv; 1063 1064 /* 1065 * We simulate a fault to get the page and enter it in the physical 1066 * map. For user wiring, we only ask for read access on currently 1067 * read-only sections. 1068 */ 1069 for (va = start; va < end; va += PAGE_SIZE) { 1070 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1071 if (rv) { 1072 if (va != start) 1073 vm_fault_unwire(map, start, va, fictitious); 1074 return (rv); 1075 } 1076 } 1077 return (KERN_SUCCESS); 1078 } 1079 1080 /* 1081 * vm_fault_unwire: 1082 * 1083 * Unwire a range of virtual addresses in a map. 1084 */ 1085 void 1086 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1087 boolean_t fictitious) 1088 { 1089 vm_paddr_t pa; 1090 vm_offset_t va; 1091 vm_page_t m; 1092 pmap_t pmap; 1093 1094 pmap = vm_map_pmap(map); 1095 1096 /* 1097 * Since the pages are wired down, we must be able to get their 1098 * mappings from the physical map system. 1099 */ 1100 for (va = start; va < end; va += PAGE_SIZE) { 1101 pa = pmap_extract(pmap, va); 1102 if (pa != 0) { 1103 pmap_change_wiring(pmap, va, FALSE); 1104 if (!fictitious) { 1105 m = PHYS_TO_VM_PAGE(pa); 1106 vm_page_lock(m); 1107 vm_page_unwire(m, TRUE); 1108 vm_page_unlock(m); 1109 } 1110 } 1111 } 1112 } 1113 1114 /* 1115 * Routine: 1116 * vm_fault_copy_entry 1117 * Function: 1118 * Create new shadow object backing dst_entry with private copy of 1119 * all underlying pages. When src_entry is equal to dst_entry, 1120 * function implements COW for wired-down map entry. Otherwise, 1121 * it forks wired entry into dst_map. 1122 * 1123 * In/out conditions: 1124 * The source and destination maps must be locked for write. 1125 * The source map entry must be wired down (or be a sharing map 1126 * entry corresponding to a main map entry that is wired down). 1127 */ 1128 void 1129 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1130 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1131 vm_ooffset_t *fork_charge) 1132 { 1133 vm_object_t backing_object, dst_object, object, src_object; 1134 vm_pindex_t dst_pindex, pindex, src_pindex; 1135 vm_prot_t access, prot; 1136 vm_offset_t vaddr; 1137 vm_page_t dst_m; 1138 vm_page_t src_m; 1139 boolean_t src_readonly, upgrade; 1140 1141 #ifdef lint 1142 src_map++; 1143 #endif /* lint */ 1144 1145 upgrade = src_entry == dst_entry; 1146 1147 src_object = src_entry->object.vm_object; 1148 src_pindex = OFF_TO_IDX(src_entry->offset); 1149 src_readonly = (src_entry->protection & VM_PROT_WRITE) == 0; 1150 1151 /* 1152 * Create the top-level object for the destination entry. (Doesn't 1153 * actually shadow anything - we copy the pages directly.) 1154 */ 1155 dst_object = vm_object_allocate(OBJT_DEFAULT, 1156 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1157 #if VM_NRESERVLEVEL > 0 1158 dst_object->flags |= OBJ_COLORED; 1159 dst_object->pg_color = atop(dst_entry->start); 1160 #endif 1161 1162 VM_OBJECT_LOCK(dst_object); 1163 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1164 ("vm_fault_copy_entry: vm_object not NULL")); 1165 dst_entry->object.vm_object = dst_object; 1166 dst_entry->offset = 0; 1167 dst_object->charge = dst_entry->end - dst_entry->start; 1168 if (fork_charge != NULL) { 1169 KASSERT(dst_entry->uip == NULL, 1170 ("vm_fault_copy_entry: leaked swp charge")); 1171 dst_object->uip = curthread->td_ucred->cr_ruidinfo; 1172 uihold(dst_object->uip); 1173 *fork_charge += dst_object->charge; 1174 } else { 1175 dst_object->uip = dst_entry->uip; 1176 dst_entry->uip = NULL; 1177 } 1178 access = prot = dst_entry->protection; 1179 /* 1180 * If not an upgrade, then enter the mappings in the pmap as 1181 * read and/or execute accesses. Otherwise, enter them as 1182 * write accesses. 1183 * 1184 * A writeable large page mapping is only created if all of 1185 * the constituent small page mappings are modified. Marking 1186 * PTEs as modified on inception allows promotion to happen 1187 * without taking potentially large number of soft faults. 1188 */ 1189 if (!upgrade) 1190 access &= ~VM_PROT_WRITE; 1191 1192 /* 1193 * Loop through all of the pages in the entry's range, copying each 1194 * one from the source object (it should be there) to the destination 1195 * object. 1196 */ 1197 for (vaddr = dst_entry->start, dst_pindex = 0; 1198 vaddr < dst_entry->end; 1199 vaddr += PAGE_SIZE, dst_pindex++) { 1200 1201 /* 1202 * Allocate a page in the destination object. 1203 */ 1204 do { 1205 dst_m = vm_page_alloc(dst_object, dst_pindex, 1206 VM_ALLOC_NORMAL); 1207 if (dst_m == NULL) { 1208 VM_OBJECT_UNLOCK(dst_object); 1209 VM_WAIT; 1210 VM_OBJECT_LOCK(dst_object); 1211 } 1212 } while (dst_m == NULL); 1213 1214 /* 1215 * Find the page in the source object, and copy it in. 1216 * (Because the source is wired down, the page will be in 1217 * memory.) 1218 */ 1219 VM_OBJECT_LOCK(src_object); 1220 object = src_object; 1221 pindex = src_pindex + dst_pindex; 1222 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1223 src_readonly && 1224 (backing_object = object->backing_object) != NULL) { 1225 /* 1226 * Allow fallback to backing objects if we are reading. 1227 */ 1228 VM_OBJECT_LOCK(backing_object); 1229 pindex += OFF_TO_IDX(object->backing_object_offset); 1230 VM_OBJECT_UNLOCK(object); 1231 object = backing_object; 1232 } 1233 if (src_m == NULL) 1234 panic("vm_fault_copy_wired: page missing"); 1235 pmap_copy_page(src_m, dst_m); 1236 VM_OBJECT_UNLOCK(object); 1237 dst_m->valid = VM_PAGE_BITS_ALL; 1238 VM_OBJECT_UNLOCK(dst_object); 1239 1240 /* 1241 * Enter it in the pmap. If a wired, copy-on-write 1242 * mapping is being replaced by a write-enabled 1243 * mapping, then wire that new mapping. 1244 */ 1245 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1246 1247 /* 1248 * Mark it no longer busy, and put it on the active list. 1249 */ 1250 VM_OBJECT_LOCK(dst_object); 1251 1252 if (upgrade) { 1253 vm_page_lock(src_m); 1254 vm_page_unwire(src_m, 0); 1255 vm_page_unlock(src_m); 1256 1257 vm_page_lock(dst_m); 1258 vm_page_wire(dst_m); 1259 vm_page_unlock(dst_m); 1260 } else { 1261 vm_page_lock(dst_m); 1262 vm_page_activate(dst_m); 1263 vm_page_unlock(dst_m); 1264 } 1265 vm_page_wakeup(dst_m); 1266 } 1267 VM_OBJECT_UNLOCK(dst_object); 1268 if (upgrade) { 1269 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1270 vm_object_deallocate(src_object); 1271 } 1272 } 1273 1274 1275 /* 1276 * This routine checks around the requested page for other pages that 1277 * might be able to be faulted in. This routine brackets the viable 1278 * pages for the pages to be paged in. 1279 * 1280 * Inputs: 1281 * m, rbehind, rahead 1282 * 1283 * Outputs: 1284 * marray (array of vm_page_t), reqpage (index of requested page) 1285 * 1286 * Return value: 1287 * number of pages in marray 1288 */ 1289 static int 1290 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1291 vm_page_t m; 1292 int rbehind; 1293 int rahead; 1294 vm_page_t *marray; 1295 int *reqpage; 1296 { 1297 int i,j; 1298 vm_object_t object; 1299 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1300 vm_page_t rtm; 1301 int cbehind, cahead; 1302 1303 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1304 1305 object = m->object; 1306 pindex = m->pindex; 1307 cbehind = cahead = 0; 1308 1309 /* 1310 * if the requested page is not available, then give up now 1311 */ 1312 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1313 return 0; 1314 } 1315 1316 if ((cbehind == 0) && (cahead == 0)) { 1317 *reqpage = 0; 1318 marray[0] = m; 1319 return 1; 1320 } 1321 1322 if (rahead > cahead) { 1323 rahead = cahead; 1324 } 1325 1326 if (rbehind > cbehind) { 1327 rbehind = cbehind; 1328 } 1329 1330 /* 1331 * scan backward for the read behind pages -- in memory 1332 */ 1333 if (pindex > 0) { 1334 if (rbehind > pindex) { 1335 rbehind = pindex; 1336 startpindex = 0; 1337 } else { 1338 startpindex = pindex - rbehind; 1339 } 1340 1341 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1342 rtm->pindex >= startpindex) 1343 startpindex = rtm->pindex + 1; 1344 1345 /* tpindex is unsigned; beware of numeric underflow. */ 1346 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1347 tpindex < pindex; i++, tpindex--) { 1348 1349 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1350 VM_ALLOC_IFNOTCACHED); 1351 if (rtm == NULL) { 1352 /* 1353 * Shift the allocated pages to the 1354 * beginning of the array. 1355 */ 1356 for (j = 0; j < i; j++) { 1357 marray[j] = marray[j + tpindex + 1 - 1358 startpindex]; 1359 } 1360 break; 1361 } 1362 1363 marray[tpindex - startpindex] = rtm; 1364 } 1365 } else { 1366 startpindex = 0; 1367 i = 0; 1368 } 1369 1370 marray[i] = m; 1371 /* page offset of the required page */ 1372 *reqpage = i; 1373 1374 tpindex = pindex + 1; 1375 i++; 1376 1377 /* 1378 * scan forward for the read ahead pages 1379 */ 1380 endpindex = tpindex + rahead; 1381 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1382 endpindex = rtm->pindex; 1383 if (endpindex > object->size) 1384 endpindex = object->size; 1385 1386 for (; tpindex < endpindex; i++, tpindex++) { 1387 1388 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1389 VM_ALLOC_IFNOTCACHED); 1390 if (rtm == NULL) { 1391 break; 1392 } 1393 1394 marray[i] = rtm; 1395 } 1396 1397 /* return number of pages */ 1398 return i; 1399 } 1400