1 /* $OpenBSD: uvm_pdaemon.c,v 1.74 2014/11/16 12:31:00 deraadt Exp $ */ 2 /* $NetBSD: uvm_pdaemon.c,v 1.23 2000/08/20 10:24:14 bjh21 Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * Copyright (c) 1991, 1993, The Regents of the University of California. 7 * 8 * All rights reserved. 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. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94 38 * from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 */ 64 65 /* 66 * uvm_pdaemon.c: the page daemon 67 */ 68 69 #include <sys/param.h> 70 #include <sys/systm.h> 71 #include <sys/kernel.h> 72 #include <sys/pool.h> 73 #include <sys/buf.h> 74 #include <sys/vnode.h> 75 #include <sys/mount.h> 76 77 #ifdef HIBERNATE 78 #include <sys/hibernate.h> 79 #endif 80 81 #include <uvm/uvm.h> 82 83 /* 84 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 85 * in a pass thru the inactive list when swap is full. the value should be 86 * "small"... if it's too large we'll cycle the active pages thru the inactive 87 * queue too quickly to for them to be referenced and avoid being freed. 88 */ 89 90 #define UVMPD_NUMDIRTYREACTS 16 91 92 93 /* 94 * local prototypes 95 */ 96 97 void uvmpd_scan(void); 98 boolean_t uvmpd_scan_inactive(struct pglist *); 99 void uvmpd_tune(void); 100 void uvmpd_drop(struct pglist *); 101 102 /* 103 * uvm_wait: wait (sleep) for the page daemon to free some pages 104 * 105 * => should be called with all locks released 106 * => should _not_ be called by the page daemon (to avoid deadlock) 107 */ 108 109 void 110 uvm_wait(const char *wmsg) 111 { 112 int timo = 0; 113 114 /* check for page daemon going to sleep (waiting for itself) */ 115 if (curproc == uvm.pagedaemon_proc) { 116 printf("uvm_wait emergency bufbackoff\n"); 117 if (bufbackoff(NULL, 4) == 0) 118 return; 119 /* 120 * now we have a problem: the pagedaemon wants to go to 121 * sleep until it frees more memory. but how can it 122 * free more memory if it is asleep? that is a deadlock. 123 * we have two options: 124 * [1] panic now 125 * [2] put a timeout on the sleep, thus causing the 126 * pagedaemon to only pause (rather than sleep forever) 127 * 128 * note that option [2] will only help us if we get lucky 129 * and some other process on the system breaks the deadlock 130 * by exiting or freeing memory (thus allowing the pagedaemon 131 * to continue). for now we panic if DEBUG is defined, 132 * otherwise we hope for the best with option [2] (better 133 * yet, this should never happen in the first place!). 134 */ 135 136 printf("pagedaemon: deadlock detected!\n"); 137 timo = hz >> 3; /* set timeout */ 138 #if defined(DEBUG) 139 /* DEBUG: panic so we can debug it */ 140 panic("pagedaemon deadlock"); 141 #endif 142 } 143 144 uvm_lock_fpageq(); 145 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 146 msleep(&uvmexp.free, &uvm.fpageqlock, PVM | PNORELOCK, wmsg, timo); 147 } 148 149 /* 150 * uvmpd_tune: tune paging parameters 151 * 152 * => called whenever memory is added to (or removed from?) the system 153 * => caller must call with page queues locked 154 */ 155 156 void 157 uvmpd_tune(void) 158 { 159 160 uvmexp.freemin = uvmexp.npages / 30; 161 162 /* between 16k and 512k */ 163 /* XXX: what are these values good for? */ 164 uvmexp.freemin = max(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 165 #if 0 166 uvmexp.freemin = min(uvmexp.freemin, (512*1024) >> PAGE_SHIFT); 167 #endif 168 169 /* Make sure there's always a user page free. */ 170 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 171 uvmexp.freemin = uvmexp.reserve_kernel + 1; 172 173 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 174 if (uvmexp.freetarg <= uvmexp.freemin) 175 uvmexp.freetarg = uvmexp.freemin + 1; 176 177 /* uvmexp.inactarg: computed in main daemon loop */ 178 179 uvmexp.wiredmax = uvmexp.npages / 3; 180 } 181 182 /* 183 * uvm_pageout: the main loop for the pagedaemon 184 */ 185 void 186 uvm_pageout(void *arg) 187 { 188 struct uvm_constraint_range constraint; 189 struct uvm_pmalloc *pma; 190 int work_done; 191 int npages = 0; 192 193 /* ensure correct priority and set paging parameters... */ 194 uvm.pagedaemon_proc = curproc; 195 (void) spl0(); 196 uvm_lock_pageq(); 197 npages = uvmexp.npages; 198 uvmpd_tune(); 199 uvm_unlock_pageq(); 200 201 for (;;) { 202 long size; 203 work_done = 0; /* No work done this iteration. */ 204 205 uvm_lock_fpageq(); 206 207 if (TAILQ_EMPTY(&uvm.pmr_control.allocs)) { 208 msleep(&uvm.pagedaemon, &uvm.fpageqlock, PVM, 209 "pgdaemon", 0); 210 uvmexp.pdwoke++; 211 } 212 213 if ((pma = TAILQ_FIRST(&uvm.pmr_control.allocs)) != NULL) { 214 pma->pm_flags |= UVM_PMA_BUSY; 215 constraint = pma->pm_constraint; 216 } else 217 constraint = no_constraint; 218 219 uvm_unlock_fpageq(); 220 221 /* now lock page queues and recompute inactive count */ 222 uvm_lock_pageq(); 223 if (npages != uvmexp.npages) { /* check for new pages? */ 224 npages = uvmexp.npages; 225 uvmpd_tune(); 226 } 227 228 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 229 if (uvmexp.inactarg <= uvmexp.freetarg) { 230 uvmexp.inactarg = uvmexp.freetarg + 1; 231 } 232 233 /* Reclaim pages from the buffer cache if possible. */ 234 size = 0; 235 if (pma != NULL) 236 size += pma->pm_size >> PAGE_SHIFT; 237 if (uvmexp.free - BUFPAGES_DEFICIT < uvmexp.freetarg) 238 size += uvmexp.freetarg - (uvmexp.free - 239 BUFPAGES_DEFICIT); 240 (void) bufbackoff(&constraint, size * 2); 241 242 /* Scan if needed to meet our targets. */ 243 if (pma != NULL || 244 ((uvmexp.free - BUFPAGES_DEFICIT) < uvmexp.freetarg) || 245 ((uvmexp.inactive + BUFPAGES_INACT) < uvmexp.inactarg)) { 246 uvmpd_scan(); 247 work_done = 1; /* XXX we hope... */ 248 } 249 250 /* 251 * if there's any free memory to be had, 252 * wake up any waiters. 253 */ 254 uvm_lock_fpageq(); 255 if (uvmexp.free > uvmexp.reserve_kernel || 256 uvmexp.paging == 0) { 257 wakeup(&uvmexp.free); 258 } 259 260 if (pma != NULL) { 261 pma->pm_flags &= ~UVM_PMA_BUSY; 262 if (!work_done) 263 pma->pm_flags |= UVM_PMA_FAIL; 264 if (pma->pm_flags & (UVM_PMA_FAIL | UVM_PMA_FREED)) { 265 pma->pm_flags &= ~UVM_PMA_LINKED; 266 TAILQ_REMOVE(&uvm.pmr_control.allocs, pma, 267 pmq); 268 } 269 wakeup(pma); 270 } 271 uvm_unlock_fpageq(); 272 273 /* scan done. unlock page queues (only lock we are holding) */ 274 uvm_unlock_pageq(); 275 276 sched_pause(); 277 } 278 /*NOTREACHED*/ 279 } 280 281 282 /* 283 * uvm_aiodone_daemon: main loop for the aiodone daemon. 284 */ 285 void 286 uvm_aiodone_daemon(void *arg) 287 { 288 int s, free; 289 struct buf *bp, *nbp; 290 291 uvm.aiodoned_proc = curproc; 292 293 for (;;) { 294 /* 295 * Check for done aio structures. If we've got structures to 296 * process, do so. Otherwise sleep while avoiding races. 297 */ 298 mtx_enter(&uvm.aiodoned_lock); 299 while ((bp = TAILQ_FIRST(&uvm.aio_done)) == NULL) 300 msleep(&uvm.aiodoned, &uvm.aiodoned_lock, 301 PVM, "aiodoned", 0); 302 /* Take the list for ourselves. */ 303 TAILQ_INIT(&uvm.aio_done); 304 mtx_leave(&uvm.aiodoned_lock); 305 306 /* process each i/o that's done. */ 307 free = uvmexp.free; 308 while (bp != NULL) { 309 if (bp->b_flags & B_PDAEMON) { 310 uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT; 311 } 312 nbp = TAILQ_NEXT(bp, b_freelist); 313 s = splbio(); /* b_iodone must by called at splbio */ 314 (*bp->b_iodone)(bp); 315 splx(s); 316 bp = nbp; 317 318 sched_pause(); 319 } 320 uvm_lock_fpageq(); 321 wakeup(free <= uvmexp.reserve_kernel ? &uvm.pagedaemon : 322 &uvmexp.free); 323 uvm_unlock_fpageq(); 324 } 325 } 326 327 328 329 /* 330 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 331 * 332 * => called with page queues locked 333 * => we work on meeting our free target by converting inactive pages 334 * into free pages. 335 * => we handle the building of swap-backed clusters 336 * => we return TRUE if we are exiting because we met our target 337 */ 338 339 boolean_t 340 uvmpd_scan_inactive(struct pglist *pglst) 341 { 342 boolean_t retval = FALSE; /* assume we haven't hit target */ 343 int free, result; 344 struct vm_page *p, *nextpg; 345 struct uvm_object *uobj; 346 struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; 347 int npages; 348 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; /* XXX: see below */ 349 int swnpages, swcpages; /* XXX: see below */ 350 int swslot; 351 struct vm_anon *anon; 352 boolean_t swap_backed; 353 vaddr_t start; 354 int dirtyreacts; 355 356 /* 357 * note: we currently keep swap-backed pages on a separate inactive 358 * list from object-backed pages. however, merging the two lists 359 * back together again hasn't been ruled out. thus, we keep our 360 * swap cluster in "swpps" rather than in pps (allows us to mix 361 * clustering types in the event of a mixed inactive queue). 362 */ 363 /* 364 * swslot is non-zero if we are building a swap cluster. we want 365 * to stay in the loop while we have a page to scan or we have 366 * a swap-cluster to build. 367 */ 368 swslot = 0; 369 swnpages = swcpages = 0; 370 free = 0; 371 dirtyreacts = 0; 372 373 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 374 /* 375 * note that p can be NULL iff we have traversed the whole 376 * list and need to do one final swap-backed clustered pageout. 377 */ 378 uobj = NULL; 379 anon = NULL; 380 381 if (p) { 382 /* 383 * update our copy of "free" and see if we've met 384 * our target 385 */ 386 free = uvmexp.free - BUFPAGES_DEFICIT; 387 388 if (free + uvmexp.paging >= uvmexp.freetarg << 2 || 389 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 390 retval = TRUE; 391 392 if (swslot == 0) { 393 /* exit now if no swap-i/o pending */ 394 break; 395 } 396 397 /* set p to null to signal final swap i/o */ 398 p = NULL; 399 } 400 } 401 402 if (p) { /* if (we have a new page to consider) */ 403 /* 404 * we are below target and have a new page to consider. 405 */ 406 uvmexp.pdscans++; 407 nextpg = TAILQ_NEXT(p, pageq); 408 409 /* 410 * move referenced pages back to active queue and 411 * skip to next page (unlikely to happen since 412 * inactive pages shouldn't have any valid mappings 413 * and we cleared reference before deactivating). 414 */ 415 416 if (pmap_is_referenced(p)) { 417 uvm_pageactivate(p); 418 uvmexp.pdreact++; 419 continue; 420 } 421 422 /* 423 * the only time we expect to see an ownerless page 424 * (i.e. a page with no uobject and !PQ_ANON) is if an 425 * anon has loaned a page from a uvm_object and the 426 * uvm_object has dropped the ownership. in that 427 * case, the anon can "take over" the loaned page 428 * and make it its own. 429 */ 430 431 /* is page part of an anon or ownerless ? */ 432 if ((p->pg_flags & PQ_ANON) || p->uobject == NULL) { 433 anon = p->uanon; 434 KASSERT(anon != NULL); 435 436 /* 437 * if the page is ownerless, claim it in the 438 * name of "anon"! 439 */ 440 if ((p->pg_flags & PQ_ANON) == 0) { 441 KASSERT(p->loan_count > 0); 442 p->loan_count--; 443 atomic_setbits_int(&p->pg_flags, 444 PQ_ANON); 445 /* anon now owns it */ 446 } 447 if (p->pg_flags & PG_BUSY) { 448 uvmexp.pdbusy++; 449 /* someone else owns page, skip it */ 450 continue; 451 } 452 uvmexp.pdanscan++; 453 } else { 454 uobj = p->uobject; 455 KASSERT(uobj != NULL); 456 if (p->pg_flags & PG_BUSY) { 457 uvmexp.pdbusy++; 458 /* someone else owns page, skip it */ 459 continue; 460 } 461 uvmexp.pdobscan++; 462 } 463 464 /* 465 * we now have the page queues locked. 466 * the page is not busy. if the page is clean we 467 * can free it now and continue. 468 */ 469 if (p->pg_flags & PG_CLEAN) { 470 if (p->pg_flags & PQ_SWAPBACKED) { 471 /* this page now lives only in swap */ 472 uvmexp.swpgonly++; 473 } 474 475 /* zap all mappings with pmap_page_protect... */ 476 pmap_page_protect(p, PROT_NONE); 477 uvm_pagefree(p); 478 uvmexp.pdfreed++; 479 480 if (anon) { 481 482 /* 483 * an anonymous page can only be clean 484 * if it has backing store assigned. 485 */ 486 487 KASSERT(anon->an_swslot != 0); 488 489 /* remove from object */ 490 anon->an_page = NULL; 491 } 492 continue; 493 } 494 495 /* 496 * this page is dirty, skip it if we'll have met our 497 * free target when all the current pageouts complete. 498 */ 499 if (free + uvmexp.paging > uvmexp.freetarg << 2) { 500 continue; 501 } 502 503 /* 504 * this page is dirty, but we can't page it out 505 * since all pages in swap are only in swap. 506 * reactivate it so that we eventually cycle 507 * all pages thru the inactive queue. 508 */ 509 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 510 if ((p->pg_flags & PQ_SWAPBACKED) && 511 uvmexp.swpgonly == uvmexp.swpages) { 512 dirtyreacts++; 513 uvm_pageactivate(p); 514 continue; 515 } 516 517 /* 518 * if the page is swap-backed and dirty and swap space 519 * is full, free any swap allocated to the page 520 * so that other pages can be paged out. 521 */ 522 KASSERT(uvmexp.swpginuse <= uvmexp.swpages); 523 if ((p->pg_flags & PQ_SWAPBACKED) && 524 uvmexp.swpginuse == uvmexp.swpages) { 525 526 if ((p->pg_flags & PQ_ANON) && 527 p->uanon->an_swslot) { 528 uvm_swap_free(p->uanon->an_swslot, 1); 529 p->uanon->an_swslot = 0; 530 } 531 if (p->pg_flags & PQ_AOBJ) { 532 uao_dropswap(p->uobject, 533 p->offset >> PAGE_SHIFT); 534 } 535 } 536 537 /* 538 * the page we are looking at is dirty. we must 539 * clean it before it can be freed. to do this we 540 * first mark the page busy so that no one else will 541 * touch the page. we write protect all the mappings 542 * of the page so that no one touches it while it is 543 * in I/O. 544 */ 545 546 swap_backed = ((p->pg_flags & PQ_SWAPBACKED) != 0); 547 atomic_setbits_int(&p->pg_flags, PG_BUSY); 548 UVM_PAGE_OWN(p, "scan_inactive"); 549 pmap_page_protect(p, PROT_READ); 550 uvmexp.pgswapout++; 551 552 /* 553 * for swap-backed pages we need to (re)allocate 554 * swap space. 555 */ 556 if (swap_backed) { 557 /* free old swap slot (if any) */ 558 if (anon) { 559 if (anon->an_swslot) { 560 uvm_swap_free(anon->an_swslot, 561 1); 562 anon->an_swslot = 0; 563 } 564 } else { 565 uao_dropswap(uobj, 566 p->offset >> PAGE_SHIFT); 567 } 568 569 /* start new cluster (if necessary) */ 570 if (swslot == 0) { 571 swnpages = MAXBSIZE >> PAGE_SHIFT; 572 swslot = uvm_swap_alloc(&swnpages, 573 TRUE); 574 if (swslot == 0) { 575 /* no swap? give up! */ 576 atomic_clearbits_int( 577 &p->pg_flags, 578 PG_BUSY); 579 UVM_PAGE_OWN(p, NULL); 580 continue; 581 } 582 swcpages = 0; /* cluster is empty */ 583 } 584 585 /* add block to cluster */ 586 swpps[swcpages] = p; 587 if (anon) 588 anon->an_swslot = swslot + swcpages; 589 else 590 uao_set_swslot(uobj, 591 p->offset >> PAGE_SHIFT, 592 swslot + swcpages); 593 swcpages++; 594 } 595 } else { 596 /* if p == NULL we must be doing a last swap i/o */ 597 swap_backed = TRUE; 598 } 599 600 /* 601 * now consider doing the pageout. 602 * 603 * for swap-backed pages, we do the pageout if we have either 604 * filled the cluster (in which case (swnpages == swcpages) or 605 * run out of pages (p == NULL). 606 * 607 * for object pages, we always do the pageout. 608 */ 609 if (swap_backed) { 610 if (p) { /* if we just added a page to cluster */ 611 /* cluster not full yet? */ 612 if (swcpages < swnpages) 613 continue; 614 } 615 616 /* starting I/O now... set up for it */ 617 npages = swcpages; 618 ppsp = swpps; 619 /* for swap-backed pages only */ 620 start = (vaddr_t) swslot; 621 622 /* if this is final pageout we could have a few 623 * extra swap blocks */ 624 if (swcpages < swnpages) { 625 uvm_swap_free(swslot + swcpages, 626 (swnpages - swcpages)); 627 } 628 } else { 629 /* normal object pageout */ 630 ppsp = pps; 631 npages = sizeof(pps) / sizeof(struct vm_page *); 632 /* not looked at because PGO_ALLPAGES is set */ 633 start = 0; 634 } 635 636 /* 637 * now do the pageout. 638 * 639 * for swap_backed pages we have already built the cluster. 640 * for !swap_backed pages, uvm_pager_put will call the object's 641 * "make put cluster" function to build a cluster on our behalf. 642 * 643 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 644 * it to free the cluster pages for us on a successful I/O (it 645 * always does this for un-successful I/O requests). this 646 * allows us to do clustered pageout without having to deal 647 * with cluster pages at this level. 648 * 649 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 650 * IN: locked: page queues 651 * OUT: locked: 652 * !locked: pageqs 653 */ 654 655 uvmexp.pdpageouts++; 656 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 657 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 658 659 /* 660 * if we did i/o to swap, zero swslot to indicate that we are 661 * no longer building a swap-backed cluster. 662 */ 663 664 if (swap_backed) 665 swslot = 0; /* done with this cluster */ 666 667 /* 668 * first, we check for VM_PAGER_PEND which means that the 669 * async I/O is in progress and the async I/O done routine 670 * will clean up after us. in this case we move on to the 671 * next page. 672 * 673 * there is a very remote chance that the pending async i/o can 674 * finish _before_ we get here. if that happens, our page "p" 675 * may no longer be on the inactive queue. so we verify this 676 * when determining the next page (starting over at the head if 677 * we've lost our inactive page). 678 */ 679 680 if (result == VM_PAGER_PEND) { 681 uvmexp.paging += npages; 682 uvm_lock_pageq(); 683 uvmexp.pdpending++; 684 if (p) { 685 if (p->pg_flags & PQ_INACTIVE) 686 nextpg = TAILQ_NEXT(p, pageq); 687 else 688 nextpg = TAILQ_FIRST(pglst); 689 } else { 690 nextpg = NULL; 691 } 692 continue; 693 } 694 695 /* clean up "p" if we have one */ 696 if (p) { 697 /* 698 * the I/O request to "p" is done and uvm_pager_put 699 * has freed any cluster pages it may have allocated 700 * during I/O. all that is left for us to do is 701 * clean up page "p" (which is still PG_BUSY). 702 * 703 * our result could be one of the following: 704 * VM_PAGER_OK: successful pageout 705 * 706 * VM_PAGER_AGAIN: tmp resource shortage, we skip 707 * to next page 708 * VM_PAGER_{FAIL,ERROR,BAD}: an error. we 709 * "reactivate" page to get it out of the way (it 710 * will eventually drift back into the inactive 711 * queue for a retry). 712 * VM_PAGER_UNLOCK: should never see this as it is 713 * only valid for "get" operations 714 */ 715 716 /* relock p's object: page queues not lock yet, so 717 * no need for "try" */ 718 719 #ifdef DIAGNOSTIC 720 if (result == VM_PAGER_UNLOCK) 721 panic("pagedaemon: pageout returned " 722 "invalid 'unlock' code"); 723 #endif 724 725 /* handle PG_WANTED now */ 726 if (p->pg_flags & PG_WANTED) 727 wakeup(p); 728 729 atomic_clearbits_int(&p->pg_flags, PG_BUSY|PG_WANTED); 730 UVM_PAGE_OWN(p, NULL); 731 732 /* released during I/O? Can only happen for anons */ 733 if (p->pg_flags & PG_RELEASED) { 734 KASSERT(anon != NULL); 735 /* 736 * remove page so we can get nextpg, 737 * also zero out anon so we don't use 738 * it after the free. 739 */ 740 anon->an_page = NULL; 741 p->uanon = NULL; 742 743 uvm_anfree(anon); /* kills anon */ 744 pmap_page_protect(p, PROT_NONE); 745 anon = NULL; 746 uvm_lock_pageq(); 747 nextpg = TAILQ_NEXT(p, pageq); 748 /* free released page */ 749 uvm_pagefree(p); 750 } else { /* page was not released during I/O */ 751 uvm_lock_pageq(); 752 nextpg = TAILQ_NEXT(p, pageq); 753 if (result != VM_PAGER_OK) { 754 /* pageout was a failure... */ 755 if (result != VM_PAGER_AGAIN) 756 uvm_pageactivate(p); 757 pmap_clear_reference(p); 758 /* XXXCDC: if (swap_backed) FREE p's 759 * swap block? */ 760 } else { 761 /* pageout was a success... */ 762 pmap_clear_reference(p); 763 pmap_clear_modify(p); 764 atomic_setbits_int(&p->pg_flags, 765 PG_CLEAN); 766 } 767 } 768 769 /* 770 * drop object lock (if there is an object left). do 771 * a safety check of nextpg to make sure it is on the 772 * inactive queue (it should be since PG_BUSY pages on 773 * the inactive queue can't be re-queued [note: not 774 * true for active queue]). 775 */ 776 777 if (nextpg && (nextpg->pg_flags & PQ_INACTIVE) == 0) { 778 nextpg = TAILQ_FIRST(pglst); /* reload! */ 779 } 780 } else { 781 /* 782 * if p is null in this loop, make sure it stays null 783 * in the next loop. 784 */ 785 nextpg = NULL; 786 787 /* 788 * lock page queues here just so they're always locked 789 * at the end of the loop. 790 */ 791 uvm_lock_pageq(); 792 } 793 } 794 return (retval); 795 } 796 797 /* 798 * uvmpd_scan: scan the page queues and attempt to meet our targets. 799 * 800 * => called with pageq's locked 801 */ 802 803 void 804 uvmpd_scan(void) 805 { 806 int free, inactive_shortage, swap_shortage, pages_freed; 807 struct vm_page *p, *nextpg; 808 struct uvm_object *uobj; 809 boolean_t got_it; 810 811 uvmexp.pdrevs++; /* counter */ 812 uobj = NULL; 813 814 /* 815 * get current "free" page count 816 */ 817 free = uvmexp.free - BUFPAGES_DEFICIT; 818 819 #ifndef __SWAP_BROKEN 820 /* 821 * swap out some processes if we are below our free target. 822 * we need to unlock the page queues for this. 823 */ 824 if (free < uvmexp.freetarg) { 825 uvmexp.pdswout++; 826 uvm_unlock_pageq(); 827 uvm_swapout_threads(); 828 uvm_lock_pageq(); 829 } 830 #endif 831 832 /* 833 * now we want to work on meeting our targets. first we work on our 834 * free target by converting inactive pages into free pages. then 835 * we work on meeting our inactive target by converting active pages 836 * to inactive ones. 837 */ 838 839 /* 840 * alternate starting queue between swap and object based on the 841 * low bit of uvmexp.pdrevs (which we bump by one each call). 842 */ 843 got_it = FALSE; 844 pages_freed = uvmexp.pdfreed; /* XXX - int */ 845 if ((uvmexp.pdrevs & 1) != 0 && uvmexp.nswapdev != 0) 846 got_it = uvmpd_scan_inactive(&uvm.page_inactive_swp); 847 if (!got_it) 848 got_it = uvmpd_scan_inactive(&uvm.page_inactive_obj); 849 if (!got_it && (uvmexp.pdrevs & 1) == 0 && uvmexp.nswapdev != 0) 850 (void) uvmpd_scan_inactive(&uvm.page_inactive_swp); 851 pages_freed = uvmexp.pdfreed - pages_freed; 852 853 /* 854 * we have done the scan to get free pages. now we work on meeting 855 * our inactive target. 856 */ 857 inactive_shortage = uvmexp.inactarg - uvmexp.inactive - BUFPAGES_INACT; 858 859 /* 860 * detect if we're not going to be able to page anything out 861 * until we free some swap resources from active pages. 862 */ 863 swap_shortage = 0; 864 if (uvmexp.free < uvmexp.freetarg && 865 uvmexp.swpginuse == uvmexp.swpages && 866 uvmexp.swpgonly < uvmexp.swpages && 867 pages_freed == 0) { 868 swap_shortage = uvmexp.freetarg - uvmexp.free; 869 } 870 871 for (p = TAILQ_FIRST(&uvm.page_active); 872 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 873 p = nextpg) { 874 nextpg = TAILQ_NEXT(p, pageq); 875 if (p->pg_flags & PG_BUSY) 876 continue; 877 878 /* is page anon owned or ownerless? */ 879 if ((p->pg_flags & PQ_ANON) || p->uobject == NULL) { 880 KASSERT(p->uanon != NULL); 881 882 /* take over the page? */ 883 if ((p->pg_flags & PQ_ANON) == 0) { 884 KASSERT(p->loan_count > 0); 885 p->loan_count--; 886 atomic_setbits_int(&p->pg_flags, PQ_ANON); 887 } 888 } 889 890 /* skip this page if it's busy. */ 891 if ((p->pg_flags & PG_BUSY) != 0) { 892 continue; 893 } 894 895 /* 896 * if there's a shortage of swap, free any swap allocated 897 * to this page so that other pages can be paged out. 898 */ 899 if (swap_shortage > 0) { 900 if ((p->pg_flags & PQ_ANON) && p->uanon->an_swslot) { 901 uvm_swap_free(p->uanon->an_swslot, 1); 902 p->uanon->an_swslot = 0; 903 atomic_clearbits_int(&p->pg_flags, PG_CLEAN); 904 swap_shortage--; 905 } 906 if (p->pg_flags & PQ_AOBJ) { 907 int slot = uao_set_swslot(p->uobject, 908 p->offset >> PAGE_SHIFT, 0); 909 if (slot) { 910 uvm_swap_free(slot, 1); 911 atomic_clearbits_int(&p->pg_flags, 912 PG_CLEAN); 913 swap_shortage--; 914 } 915 } 916 } 917 918 /* 919 * deactivate this page if there's a shortage of 920 * inactive pages. 921 */ 922 if (inactive_shortage > 0) { 923 pmap_page_protect(p, PROT_NONE); 924 /* no need to check wire_count as pg is "active" */ 925 uvm_pagedeactivate(p); 926 uvmexp.pddeact++; 927 inactive_shortage--; 928 } 929 } 930 } 931 932 #ifdef HIBERNATE 933 934 /* 935 * uvmpd_drop: drop clean pages from list 936 */ 937 void 938 uvmpd_drop(struct pglist *pglst) 939 { 940 struct vm_page *p, *nextpg; 941 942 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 943 nextpg = TAILQ_NEXT(p, pageq); 944 945 if (p->pg_flags & PQ_ANON || p->uobject == NULL) 946 continue; 947 948 if (p->pg_flags & PG_BUSY) 949 continue; 950 951 if (p->pg_flags & PG_CLEAN) { 952 /* 953 * we now have the page queues locked. 954 * the page is not busy. if the page is clean we 955 * can free it now and continue. 956 */ 957 if (p->pg_flags & PG_CLEAN) { 958 if (p->pg_flags & PQ_SWAPBACKED) { 959 /* this page now lives only in swap */ 960 uvmexp.swpgonly++; 961 } 962 963 /* zap all mappings with pmap_page_protect... */ 964 pmap_page_protect(p, PROT_NONE); 965 uvm_pagefree(p); 966 } 967 } 968 } 969 } 970 971 void 972 uvmpd_hibernate(void) 973 { 974 uvm_lock_pageq(); 975 976 uvmpd_drop(&uvm.page_inactive_swp); 977 uvmpd_drop(&uvm.page_inactive_obj); 978 uvmpd_drop(&uvm.page_active); 979 980 uvm_unlock_pageq(); 981 } 982 983 #endif 984