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]; 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 VM_OBJECT_UNLOCK(fs.object); 344 if (fs.object != fs.first_object) { 345 VM_OBJECT_LOCK(fs.first_object); 346 vm_page_lock(fs.first_m); 347 vm_page_free(fs.first_m); 348 vm_page_unlock(fs.first_m); 349 vm_object_pip_wakeup(fs.first_object); 350 VM_OBJECT_UNLOCK(fs.first_object); 351 fs.first_m = NULL; 352 } 353 unlock_map(&fs); 354 VM_OBJECT_LOCK(fs.object); 355 if (fs.m == vm_page_lookup(fs.object, 356 fs.pindex)) { 357 vm_page_sleep_if_busy(fs.m, TRUE, 358 "vmpfw"); 359 } 360 vm_object_pip_wakeup(fs.object); 361 VM_OBJECT_UNLOCK(fs.object); 362 PCPU_INC(cnt.v_intrans); 363 vm_object_deallocate(fs.first_object); 364 goto RetryFault; 365 } 366 vm_pageq_remove(fs.m); 367 vm_page_unlock(fs.m); 368 369 /* 370 * Mark page busy for other processes, and the 371 * pagedaemon. If it still isn't completely valid 372 * (readable), jump to readrest, else break-out ( we 373 * found the page ). 374 */ 375 vm_page_busy(fs.m); 376 if (fs.m->valid != VM_PAGE_BITS_ALL && 377 fs.m->object != kernel_object && fs.m->object != kmem_object) { 378 goto readrest; 379 } 380 381 break; 382 } 383 384 /* 385 * Page is not resident, If this is the search termination 386 * or the pager might contain the page, allocate a new page. 387 */ 388 if (TRYPAGER || fs.object == fs.first_object) { 389 if (fs.pindex >= fs.object->size) { 390 unlock_and_deallocate(&fs); 391 return (KERN_PROTECTION_FAILURE); 392 } 393 394 /* 395 * Allocate a new page for this object/offset pair. 396 * 397 * Unlocked read of the p_flag is harmless. At 398 * worst, the P_KILLED might be not observed 399 * there, and allocation can fail, causing 400 * restart and new reading of the p_flag. 401 */ 402 fs.m = NULL; 403 if (!vm_page_count_severe() || P_KILLED(curproc)) { 404 #if VM_NRESERVLEVEL > 0 405 if ((fs.object->flags & OBJ_COLORED) == 0) { 406 fs.object->flags |= OBJ_COLORED; 407 fs.object->pg_color = atop(vaddr) - 408 fs.pindex; 409 } 410 #endif 411 alloc_req = P_KILLED(curproc) ? 412 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 413 if (fs.object->type != OBJT_VNODE && 414 fs.object->backing_object == NULL) 415 alloc_req |= VM_ALLOC_ZERO; 416 fs.m = vm_page_alloc(fs.object, fs.pindex, 417 alloc_req); 418 } 419 if (fs.m == NULL) { 420 unlock_and_deallocate(&fs); 421 VM_WAITPFAULT; 422 goto RetryFault; 423 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 424 break; 425 } 426 427 readrest: 428 /* 429 * We have found a valid page or we have allocated a new page. 430 * The page thus may not be valid or may not be entirely 431 * valid. 432 * 433 * Attempt to fault-in the page if there is a chance that the 434 * pager has it, and potentially fault in additional pages 435 * at the same time. 436 */ 437 if (TRYPAGER) { 438 int rv; 439 int reqpage = 0; 440 u_char behavior = vm_map_entry_behavior(fs.entry); 441 442 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 443 P_KILLED(curproc)) { 444 ahead = 0; 445 behind = 0; 446 } else { 447 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 448 if (behind > VM_FAULT_READ_BEHIND) 449 behind = VM_FAULT_READ_BEHIND; 450 451 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 452 if (ahead > VM_FAULT_READ_AHEAD) 453 ahead = VM_FAULT_READ_AHEAD; 454 } 455 is_first_object_locked = FALSE; 456 if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 457 (behavior != MAP_ENTRY_BEHAV_RANDOM && 458 fs.pindex >= fs.entry->lastr && 459 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) && 460 (fs.first_object == fs.object || 461 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) && 462 fs.first_object->type != OBJT_DEVICE && 463 fs.first_object->type != OBJT_PHYS && 464 fs.first_object->type != OBJT_SG) { 465 vm_pindex_t firstpindex, tmppindex; 466 467 if (fs.first_pindex < 2 * VM_FAULT_READ) 468 firstpindex = 0; 469 else 470 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 471 472 /* 473 * note: partially valid pages cannot be 474 * included in the lookahead - NFS piecemeal 475 * writes will barf on it badly. 476 */ 477 for (tmppindex = fs.first_pindex - 1; 478 tmppindex >= firstpindex; 479 --tmppindex) { 480 vm_page_t mt; 481 482 mt = vm_page_lookup(fs.first_object, tmppindex); 483 if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL)) 484 break; 485 if (mt->busy || 486 (mt->oflags & VPO_BUSY)) 487 continue; 488 vm_page_lock(mt); 489 if (mt->hold_count || 490 mt->wire_count) { 491 vm_page_unlock(mt); 492 continue; 493 } 494 pmap_remove_all(mt); 495 if (mt->dirty != 0) 496 vm_page_deactivate(mt); 497 else 498 vm_page_cache(mt); 499 vm_page_unlock(mt); 500 } 501 ahead += behind; 502 behind = 0; 503 } 504 if (is_first_object_locked) 505 VM_OBJECT_UNLOCK(fs.first_object); 506 507 /* 508 * Call the pager to retrieve the data, if any, after 509 * releasing the lock on the map. We hold a ref on 510 * fs.object and the pages are VPO_BUSY'd. 511 */ 512 unlock_map(&fs); 513 514 vnode_lock: 515 if (fs.object->type == OBJT_VNODE) { 516 vp = fs.object->handle; 517 if (vp == fs.vp) 518 goto vnode_locked; 519 else if (fs.vp != NULL) { 520 vput(fs.vp); 521 fs.vp = NULL; 522 } 523 locked = VOP_ISLOCKED(vp); 524 525 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 526 fs.vfslocked = 1; 527 if (!mtx_trylock(&Giant)) { 528 VM_OBJECT_UNLOCK(fs.object); 529 mtx_lock(&Giant); 530 VM_OBJECT_LOCK(fs.object); 531 goto vnode_lock; 532 } 533 } 534 if (locked != LK_EXCLUSIVE) 535 locked = LK_SHARED; 536 /* Do not sleep for vnode lock while fs.m is busy */ 537 error = vget(vp, locked | LK_CANRECURSE | 538 LK_NOWAIT, curthread); 539 if (error != 0) { 540 int vfslocked; 541 542 vfslocked = fs.vfslocked; 543 fs.vfslocked = 0; /* Keep Giant */ 544 vhold(vp); 545 release_page(&fs); 546 unlock_and_deallocate(&fs); 547 error = vget(vp, locked | LK_RETRY | 548 LK_CANRECURSE, curthread); 549 vdrop(vp); 550 fs.vp = vp; 551 fs.vfslocked = vfslocked; 552 KASSERT(error == 0, 553 ("vm_fault: vget failed")); 554 goto RetryFault; 555 } 556 fs.vp = vp; 557 } 558 vnode_locked: 559 KASSERT(fs.vp == NULL || !fs.map->system_map, 560 ("vm_fault: vnode-backed object mapped by system map")); 561 562 /* 563 * now we find out if any other pages should be paged 564 * in at this time this routine checks to see if the 565 * pages surrounding this fault reside in the same 566 * object as the page for this fault. If they do, 567 * then they are faulted in also into the object. The 568 * array "marray" returned contains an array of 569 * vm_page_t structs where one of them is the 570 * vm_page_t passed to the routine. The reqpage 571 * return value is the index into the marray for the 572 * vm_page_t passed to the routine. 573 * 574 * fs.m plus the additional pages are VPO_BUSY'd. 575 */ 576 faultcount = vm_fault_additional_pages( 577 fs.m, behind, ahead, marray, &reqpage); 578 579 rv = faultcount ? 580 vm_pager_get_pages(fs.object, marray, faultcount, 581 reqpage) : VM_PAGER_FAIL; 582 583 if (rv == VM_PAGER_OK) { 584 /* 585 * Found the page. Leave it busy while we play 586 * with it. 587 */ 588 589 /* 590 * Relookup in case pager changed page. Pager 591 * is responsible for disposition of old page 592 * if moved. 593 */ 594 fs.m = vm_page_lookup(fs.object, fs.pindex); 595 if (!fs.m) { 596 unlock_and_deallocate(&fs); 597 goto RetryFault; 598 } 599 600 hardfault++; 601 break; /* break to PAGE HAS BEEN FOUND */ 602 } 603 /* 604 * Remove the bogus page (which does not exist at this 605 * object/offset); before doing so, we must get back 606 * our object lock to preserve our invariant. 607 * 608 * Also wake up any other process that may want to bring 609 * in this page. 610 * 611 * If this is the top-level object, we must leave the 612 * busy page to prevent another process from rushing 613 * past us, and inserting the page in that object at 614 * the same time that we are. 615 */ 616 if (rv == VM_PAGER_ERROR) 617 printf("vm_fault: pager read error, pid %d (%s)\n", 618 curproc->p_pid, curproc->p_comm); 619 /* 620 * Data outside the range of the pager or an I/O error 621 */ 622 /* 623 * XXX - the check for kernel_map is a kludge to work 624 * around having the machine panic on a kernel space 625 * fault w/ I/O error. 626 */ 627 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 628 (rv == VM_PAGER_BAD)) { 629 vm_page_lock(fs.m); 630 vm_page_free(fs.m); 631 vm_page_unlock(fs.m); 632 fs.m = NULL; 633 unlock_and_deallocate(&fs); 634 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 635 } 636 if (fs.object != fs.first_object) { 637 vm_page_lock(fs.m); 638 vm_page_free(fs.m); 639 vm_page_unlock(fs.m); 640 fs.m = NULL; 641 /* 642 * XXX - we cannot just fall out at this 643 * point, m has been freed and is invalid! 644 */ 645 } 646 } 647 648 /* 649 * We get here if the object has default pager (or unwiring) 650 * or the pager doesn't have the page. 651 */ 652 if (fs.object == fs.first_object) 653 fs.first_m = fs.m; 654 655 /* 656 * Move on to the next object. Lock the next object before 657 * unlocking the current one. 658 */ 659 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 660 next_object = fs.object->backing_object; 661 if (next_object == NULL) { 662 /* 663 * If there's no object left, fill the page in the top 664 * object with zeros. 665 */ 666 if (fs.object != fs.first_object) { 667 vm_object_pip_wakeup(fs.object); 668 VM_OBJECT_UNLOCK(fs.object); 669 670 fs.object = fs.first_object; 671 fs.pindex = fs.first_pindex; 672 fs.m = fs.first_m; 673 VM_OBJECT_LOCK(fs.object); 674 } 675 fs.first_m = NULL; 676 677 /* 678 * Zero the page if necessary and mark it valid. 679 */ 680 if ((fs.m->flags & PG_ZERO) == 0) { 681 pmap_zero_page(fs.m); 682 } else { 683 PCPU_INC(cnt.v_ozfod); 684 } 685 PCPU_INC(cnt.v_zfod); 686 fs.m->valid = VM_PAGE_BITS_ALL; 687 break; /* break to PAGE HAS BEEN FOUND */ 688 } else { 689 KASSERT(fs.object != next_object, 690 ("object loop %p", next_object)); 691 VM_OBJECT_LOCK(next_object); 692 vm_object_pip_add(next_object, 1); 693 if (fs.object != fs.first_object) 694 vm_object_pip_wakeup(fs.object); 695 VM_OBJECT_UNLOCK(fs.object); 696 fs.object = next_object; 697 } 698 } 699 700 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 701 ("vm_fault: not busy after main loop")); 702 703 /* 704 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 705 * is held.] 706 */ 707 708 /* 709 * If the page is being written, but isn't already owned by the 710 * top-level object, we have to copy it into a new page owned by the 711 * top-level object. 712 */ 713 if (fs.object != fs.first_object) { 714 /* 715 * We only really need to copy if we want to write it. 716 */ 717 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 718 /* 719 * This allows pages to be virtually copied from a 720 * backing_object into the first_object, where the 721 * backing object has no other refs to it, and cannot 722 * gain any more refs. Instead of a bcopy, we just 723 * move the page from the backing object to the 724 * first object. Note that we must mark the page 725 * dirty in the first object so that it will go out 726 * to swap when needed. 727 */ 728 is_first_object_locked = FALSE; 729 if ( 730 /* 731 * Only one shadow object 732 */ 733 (fs.object->shadow_count == 1) && 734 /* 735 * No COW refs, except us 736 */ 737 (fs.object->ref_count == 1) && 738 /* 739 * No one else can look this object up 740 */ 741 (fs.object->handle == NULL) && 742 /* 743 * No other ways to look the object up 744 */ 745 ((fs.object->type == OBJT_DEFAULT) || 746 (fs.object->type == OBJT_SWAP)) && 747 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 748 /* 749 * We don't chase down the shadow chain 750 */ 751 fs.object == fs.first_object->backing_object) { 752 /* 753 * get rid of the unnecessary page 754 */ 755 vm_page_lock(fs.first_m); 756 vm_page_free(fs.first_m); 757 vm_page_unlock(fs.first_m); 758 /* 759 * grab the page and put it into the 760 * process'es object. The page is 761 * automatically made dirty. 762 */ 763 vm_page_lock(fs.m); 764 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 765 vm_page_unlock(fs.m); 766 vm_page_busy(fs.m); 767 fs.first_m = fs.m; 768 fs.m = NULL; 769 PCPU_INC(cnt.v_cow_optim); 770 } else { 771 /* 772 * Oh, well, lets copy it. 773 */ 774 pmap_copy_page(fs.m, fs.first_m); 775 fs.first_m->valid = VM_PAGE_BITS_ALL; 776 if (wired && (fault_flags & 777 VM_FAULT_CHANGE_WIRING) == 0) { 778 vm_page_lock(fs.first_m); 779 vm_page_wire(fs.first_m); 780 vm_page_unlock(fs.first_m); 781 782 vm_page_lock(fs.m); 783 vm_page_unwire(fs.m, FALSE); 784 vm_page_unlock(fs.m); 785 } 786 /* 787 * We no longer need the old page or object. 788 */ 789 release_page(&fs); 790 } 791 /* 792 * fs.object != fs.first_object due to above 793 * conditional 794 */ 795 vm_object_pip_wakeup(fs.object); 796 VM_OBJECT_UNLOCK(fs.object); 797 /* 798 * Only use the new page below... 799 */ 800 fs.object = fs.first_object; 801 fs.pindex = fs.first_pindex; 802 fs.m = fs.first_m; 803 if (!is_first_object_locked) 804 VM_OBJECT_LOCK(fs.object); 805 PCPU_INC(cnt.v_cow_faults); 806 } else { 807 prot &= ~VM_PROT_WRITE; 808 } 809 } 810 811 /* 812 * We must verify that the maps have not changed since our last 813 * lookup. 814 */ 815 if (!fs.lookup_still_valid) { 816 vm_object_t retry_object; 817 vm_pindex_t retry_pindex; 818 vm_prot_t retry_prot; 819 820 if (!vm_map_trylock_read(fs.map)) { 821 release_page(&fs); 822 unlock_and_deallocate(&fs); 823 goto RetryFault; 824 } 825 fs.lookup_still_valid = TRUE; 826 if (fs.map->timestamp != map_generation) { 827 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 828 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 829 830 /* 831 * If we don't need the page any longer, put it on the inactive 832 * list (the easiest thing to do here). If no one needs it, 833 * pageout will grab it eventually. 834 */ 835 if (result != KERN_SUCCESS) { 836 release_page(&fs); 837 unlock_and_deallocate(&fs); 838 839 /* 840 * If retry of map lookup would have blocked then 841 * retry fault from start. 842 */ 843 if (result == KERN_FAILURE) 844 goto RetryFault; 845 return (result); 846 } 847 if ((retry_object != fs.first_object) || 848 (retry_pindex != fs.first_pindex)) { 849 release_page(&fs); 850 unlock_and_deallocate(&fs); 851 goto RetryFault; 852 } 853 854 /* 855 * Check whether the protection has changed or the object has 856 * been copied while we left the map unlocked. Changing from 857 * read to write permission is OK - we leave the page 858 * write-protected, and catch the write fault. Changing from 859 * write to read permission means that we can't mark the page 860 * write-enabled after all. 861 */ 862 prot &= retry_prot; 863 } 864 } 865 /* 866 * If the page was filled by a pager, update the map entry's 867 * last read offset. Since the pager does not return the 868 * actual set of pages that it read, this update is based on 869 * the requested set. Typically, the requested and actual 870 * sets are the same. 871 * 872 * XXX The following assignment modifies the map 873 * without holding a write lock on it. 874 */ 875 if (hardfault) 876 fs.entry->lastr = fs.pindex + faultcount - behind; 877 878 if (prot & VM_PROT_WRITE) { 879 vm_object_set_writeable_dirty(fs.object); 880 881 /* 882 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 883 * if the page is already dirty to prevent data written with 884 * the expectation of being synced from not being synced. 885 * Likewise if this entry does not request NOSYNC then make 886 * sure the page isn't marked NOSYNC. Applications sharing 887 * data should use the same flags to avoid ping ponging. 888 */ 889 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 890 if (fs.m->dirty == 0) 891 fs.m->oflags |= VPO_NOSYNC; 892 } else { 893 fs.m->oflags &= ~VPO_NOSYNC; 894 } 895 896 /* 897 * If the fault is a write, we know that this page is being 898 * written NOW so dirty it explicitly to save on 899 * pmap_is_modified() calls later. 900 * 901 * Also tell the backing pager, if any, that it should remove 902 * any swap backing since the page is now dirty. 903 */ 904 if ((fault_type & VM_PROT_WRITE) != 0 && 905 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) { 906 vm_page_dirty(fs.m); 907 vm_pager_page_unswapped(fs.m); 908 } 909 } 910 911 /* 912 * Page had better still be busy 913 */ 914 KASSERT(fs.m->oflags & VPO_BUSY, 915 ("vm_fault: page %p not busy!", fs.m)); 916 /* 917 * Page must be completely valid or it is not fit to 918 * map into user space. vm_pager_get_pages() ensures this. 919 */ 920 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 921 ("vm_fault: page %p partially invalid", fs.m)); 922 VM_OBJECT_UNLOCK(fs.object); 923 924 /* 925 * Put this page into the physical map. We had to do the unlock above 926 * because pmap_enter() may sleep. We don't put the page 927 * back on the active queue until later so that the pageout daemon 928 * won't find it (yet). 929 */ 930 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 931 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 932 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 933 VM_OBJECT_LOCK(fs.object); 934 vm_page_lock(fs.m); 935 936 /* 937 * If the page is not wired down, then put it where the pageout daemon 938 * can find it. 939 */ 940 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 941 if (wired) 942 vm_page_wire(fs.m); 943 else 944 vm_page_unwire(fs.m, 1); 945 } else 946 vm_page_activate(fs.m); 947 vm_page_unlock(fs.m); 948 vm_page_wakeup(fs.m); 949 950 /* 951 * Unlock everything, and return 952 */ 953 unlock_and_deallocate(&fs); 954 if (hardfault) 955 curthread->td_ru.ru_majflt++; 956 else 957 curthread->td_ru.ru_minflt++; 958 959 return (KERN_SUCCESS); 960 } 961 962 /* 963 * vm_fault_prefault provides a quick way of clustering 964 * pagefaults into a processes address space. It is a "cousin" 965 * of vm_map_pmap_enter, except it runs at page fault time instead 966 * of mmap time. 967 */ 968 static void 969 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 970 { 971 int i; 972 vm_offset_t addr, starta; 973 vm_pindex_t pindex; 974 vm_page_t m; 975 vm_object_t object; 976 977 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 978 return; 979 980 object = entry->object.vm_object; 981 982 starta = addra - PFBAK * PAGE_SIZE; 983 if (starta < entry->start) { 984 starta = entry->start; 985 } else if (starta > addra) { 986 starta = 0; 987 } 988 989 for (i = 0; i < PAGEORDER_SIZE; i++) { 990 vm_object_t backing_object, lobject; 991 992 addr = addra + prefault_pageorder[i]; 993 if (addr > addra + (PFFOR * PAGE_SIZE)) 994 addr = 0; 995 996 if (addr < starta || addr >= entry->end) 997 continue; 998 999 if (!pmap_is_prefaultable(pmap, addr)) 1000 continue; 1001 1002 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1003 lobject = object; 1004 VM_OBJECT_LOCK(lobject); 1005 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1006 lobject->type == OBJT_DEFAULT && 1007 (backing_object = lobject->backing_object) != NULL) { 1008 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1009 0, ("vm_fault_prefault: unaligned object offset")); 1010 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1011 VM_OBJECT_LOCK(backing_object); 1012 VM_OBJECT_UNLOCK(lobject); 1013 lobject = backing_object; 1014 } 1015 /* 1016 * give-up when a page is not in memory 1017 */ 1018 if (m == NULL) { 1019 VM_OBJECT_UNLOCK(lobject); 1020 break; 1021 } 1022 if (m->valid == VM_PAGE_BITS_ALL && 1023 (m->flags & PG_FICTITIOUS) == 0) 1024 pmap_enter_quick(pmap, addr, m, entry->protection); 1025 VM_OBJECT_UNLOCK(lobject); 1026 } 1027 } 1028 1029 /* 1030 * vm_fault_quick: 1031 * 1032 * Ensure that the requested virtual address, which may be in userland, 1033 * is valid. Fault-in the page if necessary. Return -1 on failure. 1034 */ 1035 int 1036 vm_fault_quick(caddr_t v, int prot) 1037 { 1038 int r; 1039 1040 if (prot & VM_PROT_WRITE) 1041 r = subyte(v, fubyte(v)); 1042 else 1043 r = fubyte(v); 1044 return(r); 1045 } 1046 1047 /* 1048 * vm_fault_wire: 1049 * 1050 * Wire down a range of virtual addresses in a map. 1051 */ 1052 int 1053 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1054 boolean_t fictitious) 1055 { 1056 vm_offset_t va; 1057 int rv; 1058 1059 /* 1060 * We simulate a fault to get the page and enter it in the physical 1061 * map. For user wiring, we only ask for read access on currently 1062 * read-only sections. 1063 */ 1064 for (va = start; va < end; va += PAGE_SIZE) { 1065 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1066 if (rv) { 1067 if (va != start) 1068 vm_fault_unwire(map, start, va, fictitious); 1069 return (rv); 1070 } 1071 } 1072 return (KERN_SUCCESS); 1073 } 1074 1075 /* 1076 * vm_fault_unwire: 1077 * 1078 * Unwire a range of virtual addresses in a map. 1079 */ 1080 void 1081 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1082 boolean_t fictitious) 1083 { 1084 vm_paddr_t pa; 1085 vm_offset_t va; 1086 vm_page_t m; 1087 pmap_t pmap; 1088 1089 pmap = vm_map_pmap(map); 1090 1091 /* 1092 * Since the pages are wired down, we must be able to get their 1093 * mappings from the physical map system. 1094 */ 1095 for (va = start; va < end; va += PAGE_SIZE) { 1096 pa = pmap_extract(pmap, va); 1097 if (pa != 0) { 1098 pmap_change_wiring(pmap, va, FALSE); 1099 if (!fictitious) { 1100 m = PHYS_TO_VM_PAGE(pa); 1101 vm_page_lock(m); 1102 vm_page_unwire(m, TRUE); 1103 vm_page_unlock(m); 1104 } 1105 } 1106 } 1107 } 1108 1109 /* 1110 * Routine: 1111 * vm_fault_copy_entry 1112 * Function: 1113 * Create new shadow object backing dst_entry with private copy of 1114 * all underlying pages. When src_entry is equal to dst_entry, 1115 * function implements COW for wired-down map entry. Otherwise, 1116 * it forks wired entry into dst_map. 1117 * 1118 * In/out conditions: 1119 * The source and destination maps must be locked for write. 1120 * The source map entry must be wired down (or be a sharing map 1121 * entry corresponding to a main map entry that is wired down). 1122 */ 1123 void 1124 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1125 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1126 vm_ooffset_t *fork_charge) 1127 { 1128 vm_object_t backing_object, dst_object, object, src_object; 1129 vm_pindex_t dst_pindex, pindex, src_pindex; 1130 vm_prot_t access, prot; 1131 vm_offset_t vaddr; 1132 vm_page_t dst_m; 1133 vm_page_t src_m; 1134 boolean_t src_readonly, upgrade; 1135 1136 #ifdef lint 1137 src_map++; 1138 #endif /* lint */ 1139 1140 upgrade = src_entry == dst_entry; 1141 1142 src_object = src_entry->object.vm_object; 1143 src_pindex = OFF_TO_IDX(src_entry->offset); 1144 src_readonly = (src_entry->protection & VM_PROT_WRITE) == 0; 1145 1146 /* 1147 * Create the top-level object for the destination entry. (Doesn't 1148 * actually shadow anything - we copy the pages directly.) 1149 */ 1150 dst_object = vm_object_allocate(OBJT_DEFAULT, 1151 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1152 #if VM_NRESERVLEVEL > 0 1153 dst_object->flags |= OBJ_COLORED; 1154 dst_object->pg_color = atop(dst_entry->start); 1155 #endif 1156 1157 VM_OBJECT_LOCK(dst_object); 1158 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1159 ("vm_fault_copy_entry: vm_object not NULL")); 1160 dst_entry->object.vm_object = dst_object; 1161 dst_entry->offset = 0; 1162 dst_object->charge = dst_entry->end - dst_entry->start; 1163 if (fork_charge != NULL) { 1164 KASSERT(dst_entry->uip == NULL, 1165 ("vm_fault_copy_entry: leaked swp charge")); 1166 dst_object->uip = curthread->td_ucred->cr_ruidinfo; 1167 uihold(dst_object->uip); 1168 *fork_charge += dst_object->charge; 1169 } else { 1170 dst_object->uip = dst_entry->uip; 1171 dst_entry->uip = NULL; 1172 } 1173 access = prot = dst_entry->protection; 1174 /* 1175 * If not an upgrade, then enter the mappings in the pmap as 1176 * read and/or execute accesses. Otherwise, enter them as 1177 * write accesses. 1178 * 1179 * A writeable large page mapping is only created if all of 1180 * the constituent small page mappings are modified. Marking 1181 * PTEs as modified on inception allows promotion to happen 1182 * without taking potentially large number of soft faults. 1183 */ 1184 if (!upgrade) 1185 access &= ~VM_PROT_WRITE; 1186 1187 /* 1188 * Loop through all of the pages in the entry's range, copying each 1189 * one from the source object (it should be there) to the destination 1190 * object. 1191 */ 1192 for (vaddr = dst_entry->start, dst_pindex = 0; 1193 vaddr < dst_entry->end; 1194 vaddr += PAGE_SIZE, dst_pindex++) { 1195 1196 /* 1197 * Allocate a page in the destination object. 1198 */ 1199 do { 1200 dst_m = vm_page_alloc(dst_object, dst_pindex, 1201 VM_ALLOC_NORMAL); 1202 if (dst_m == NULL) { 1203 VM_OBJECT_UNLOCK(dst_object); 1204 VM_WAIT; 1205 VM_OBJECT_LOCK(dst_object); 1206 } 1207 } while (dst_m == NULL); 1208 1209 /* 1210 * Find the page in the source object, and copy it in. 1211 * (Because the source is wired down, the page will be in 1212 * memory.) 1213 */ 1214 VM_OBJECT_LOCK(src_object); 1215 object = src_object; 1216 pindex = src_pindex + dst_pindex; 1217 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1218 src_readonly && 1219 (backing_object = object->backing_object) != NULL) { 1220 /* 1221 * Allow fallback to backing objects if we are reading. 1222 */ 1223 VM_OBJECT_LOCK(backing_object); 1224 pindex += OFF_TO_IDX(object->backing_object_offset); 1225 VM_OBJECT_UNLOCK(object); 1226 object = backing_object; 1227 } 1228 if (src_m == NULL) 1229 panic("vm_fault_copy_wired: page missing"); 1230 pmap_copy_page(src_m, dst_m); 1231 VM_OBJECT_UNLOCK(object); 1232 dst_m->valid = VM_PAGE_BITS_ALL; 1233 VM_OBJECT_UNLOCK(dst_object); 1234 1235 /* 1236 * Enter it in the pmap. If a wired, copy-on-write 1237 * mapping is being replaced by a write-enabled 1238 * mapping, then wire that new mapping. 1239 */ 1240 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1241 1242 /* 1243 * Mark it no longer busy, and put it on the active list. 1244 */ 1245 VM_OBJECT_LOCK(dst_object); 1246 1247 if (upgrade) { 1248 vm_page_lock(src_m); 1249 vm_page_unwire(src_m, 0); 1250 vm_page_unlock(src_m); 1251 1252 vm_page_lock(dst_m); 1253 vm_page_wire(dst_m); 1254 vm_page_unlock(dst_m); 1255 } else { 1256 vm_page_lock(dst_m); 1257 vm_page_activate(dst_m); 1258 vm_page_unlock(dst_m); 1259 } 1260 vm_page_wakeup(dst_m); 1261 } 1262 VM_OBJECT_UNLOCK(dst_object); 1263 if (upgrade) { 1264 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1265 vm_object_deallocate(src_object); 1266 } 1267 } 1268 1269 1270 /* 1271 * This routine checks around the requested page for other pages that 1272 * might be able to be faulted in. This routine brackets the viable 1273 * pages for the pages to be paged in. 1274 * 1275 * Inputs: 1276 * m, rbehind, rahead 1277 * 1278 * Outputs: 1279 * marray (array of vm_page_t), reqpage (index of requested page) 1280 * 1281 * Return value: 1282 * number of pages in marray 1283 */ 1284 static int 1285 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1286 vm_page_t m; 1287 int rbehind; 1288 int rahead; 1289 vm_page_t *marray; 1290 int *reqpage; 1291 { 1292 int i,j; 1293 vm_object_t object; 1294 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1295 vm_page_t rtm; 1296 int cbehind, cahead; 1297 1298 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1299 1300 object = m->object; 1301 pindex = m->pindex; 1302 cbehind = cahead = 0; 1303 1304 /* 1305 * if the requested page is not available, then give up now 1306 */ 1307 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1308 return 0; 1309 } 1310 1311 if ((cbehind == 0) && (cahead == 0)) { 1312 *reqpage = 0; 1313 marray[0] = m; 1314 return 1; 1315 } 1316 1317 if (rahead > cahead) { 1318 rahead = cahead; 1319 } 1320 1321 if (rbehind > cbehind) { 1322 rbehind = cbehind; 1323 } 1324 1325 /* 1326 * scan backward for the read behind pages -- in memory 1327 */ 1328 if (pindex > 0) { 1329 if (rbehind > pindex) { 1330 rbehind = pindex; 1331 startpindex = 0; 1332 } else { 1333 startpindex = pindex - rbehind; 1334 } 1335 1336 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1337 rtm->pindex >= startpindex) 1338 startpindex = rtm->pindex + 1; 1339 1340 /* tpindex is unsigned; beware of numeric underflow. */ 1341 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1342 tpindex < pindex; i++, tpindex--) { 1343 1344 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1345 VM_ALLOC_IFNOTCACHED); 1346 if (rtm == NULL) { 1347 /* 1348 * Shift the allocated pages to the 1349 * beginning of the array. 1350 */ 1351 for (j = 0; j < i; j++) { 1352 marray[j] = marray[j + tpindex + 1 - 1353 startpindex]; 1354 } 1355 break; 1356 } 1357 1358 marray[tpindex - startpindex] = rtm; 1359 } 1360 } else { 1361 startpindex = 0; 1362 i = 0; 1363 } 1364 1365 marray[i] = m; 1366 /* page offset of the required page */ 1367 *reqpage = i; 1368 1369 tpindex = pindex + 1; 1370 i++; 1371 1372 /* 1373 * scan forward for the read ahead pages 1374 */ 1375 endpindex = tpindex + rahead; 1376 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1377 endpindex = rtm->pindex; 1378 if (endpindex > object->size) 1379 endpindex = object->size; 1380 1381 for (; tpindex < endpindex; i++, tpindex++) { 1382 1383 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1384 VM_ALLOC_IFNOTCACHED); 1385 if (rtm == NULL) { 1386 break; 1387 } 1388 1389 marray[i] = rtm; 1390 } 1391 1392 /* return number of pages */ 1393 return i; 1394 } 1395