1 /* $OpenBSD: uvm_pdaemon.c,v 1.105 2022/09/10 20:35:29 miod 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/proc.h> 74 #include <sys/buf.h> 75 #include <sys/mount.h> 76 #include <sys/atomic.h> 77 78 #ifdef HIBERNATE 79 #include <sys/hibernate.h> 80 #endif 81 82 #include <uvm/uvm.h> 83 84 #include "drm.h" 85 86 #if NDRM > 0 87 extern void drmbackoff(long); 88 #endif 89 90 /* 91 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 92 * in a pass thru the inactive list when swap is full. the value should be 93 * "small"... if it's too large we'll cycle the active pages thru the inactive 94 * queue too quickly to for them to be referenced and avoid being freed. 95 */ 96 97 #define UVMPD_NUMDIRTYREACTS 16 98 99 100 /* 101 * local prototypes 102 */ 103 104 struct rwlock *uvmpd_trylockowner(struct vm_page *); 105 void uvmpd_scan(struct uvm_pmalloc *); 106 void uvmpd_scan_inactive(struct uvm_pmalloc *, struct pglist *); 107 void uvmpd_tune(void); 108 void uvmpd_drop(struct pglist *); 109 void uvmpd_dropswap(struct vm_page *); 110 111 /* 112 * uvm_wait: wait (sleep) for the page daemon to free some pages 113 * 114 * => should be called with all locks released 115 * => should _not_ be called by the page daemon (to avoid deadlock) 116 */ 117 118 void 119 uvm_wait(const char *wmsg) 120 { 121 uint64_t timo = INFSLP; 122 123 #ifdef DIAGNOSTIC 124 if (curproc == &proc0) 125 panic("%s: cannot sleep for memory during boot", __func__); 126 #endif 127 128 /* 129 * check for page daemon going to sleep (waiting for itself) 130 */ 131 if (curproc == uvm.pagedaemon_proc) { 132 printf("uvm_wait emergency bufbackoff\n"); 133 if (bufbackoff(NULL, 4) == 0) 134 return; 135 /* 136 * now we have a problem: the pagedaemon wants to go to 137 * sleep until it frees more memory. but how can it 138 * free more memory if it is asleep? that is a deadlock. 139 * we have two options: 140 * [1] panic now 141 * [2] put a timeout on the sleep, thus causing the 142 * pagedaemon to only pause (rather than sleep forever) 143 * 144 * note that option [2] will only help us if we get lucky 145 * and some other process on the system breaks the deadlock 146 * by exiting or freeing memory (thus allowing the pagedaemon 147 * to continue). for now we panic if DEBUG is defined, 148 * otherwise we hope for the best with option [2] (better 149 * yet, this should never happen in the first place!). 150 */ 151 152 printf("pagedaemon: deadlock detected!\n"); 153 timo = MSEC_TO_NSEC(125); /* set timeout */ 154 #if defined(DEBUG) 155 /* DEBUG: panic so we can debug it */ 156 panic("pagedaemon deadlock"); 157 #endif 158 } 159 160 uvm_lock_fpageq(); 161 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 162 msleep_nsec(&uvmexp.free, &uvm.fpageqlock, PVM | PNORELOCK, wmsg, timo); 163 } 164 165 /* 166 * uvmpd_tune: tune paging parameters 167 * 168 * => called whenever memory is added to (or removed from?) the system 169 * => caller must call with page queues locked 170 */ 171 172 void 173 uvmpd_tune(void) 174 { 175 176 uvmexp.freemin = uvmexp.npages / 30; 177 178 /* between 16k and 512k */ 179 /* XXX: what are these values good for? */ 180 uvmexp.freemin = max(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 181 #if 0 182 uvmexp.freemin = min(uvmexp.freemin, (512*1024) >> PAGE_SHIFT); 183 #endif 184 185 /* Make sure there's always a user page free. */ 186 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 187 uvmexp.freemin = uvmexp.reserve_kernel + 1; 188 189 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 190 if (uvmexp.freetarg <= uvmexp.freemin) 191 uvmexp.freetarg = uvmexp.freemin + 1; 192 193 /* uvmexp.inactarg: computed in main daemon loop */ 194 195 uvmexp.wiredmax = uvmexp.npages / 3; 196 } 197 198 /* 199 * Indicate to the page daemon that a nowait call failed and it should 200 * recover at least some memory in the most restricted region (assumed 201 * to be dma_constraint). 202 */ 203 volatile int uvm_nowait_failed; 204 205 /* 206 * uvm_pageout: the main loop for the pagedaemon 207 */ 208 void 209 uvm_pageout(void *arg) 210 { 211 struct uvm_constraint_range constraint; 212 struct uvm_pmalloc *pma; 213 int npages = 0; 214 215 /* ensure correct priority and set paging parameters... */ 216 uvm.pagedaemon_proc = curproc; 217 (void) spl0(); 218 uvm_lock_pageq(); 219 npages = uvmexp.npages; 220 uvmpd_tune(); 221 uvm_unlock_pageq(); 222 223 for (;;) { 224 long size; 225 226 uvm_lock_fpageq(); 227 if (!uvm_nowait_failed && TAILQ_EMPTY(&uvm.pmr_control.allocs)) { 228 msleep_nsec(&uvm.pagedaemon, &uvm.fpageqlock, PVM, 229 "pgdaemon", INFSLP); 230 uvmexp.pdwoke++; 231 } 232 233 if ((pma = TAILQ_FIRST(&uvm.pmr_control.allocs)) != NULL) { 234 pma->pm_flags |= UVM_PMA_BUSY; 235 constraint = pma->pm_constraint; 236 } else { 237 if (uvm_nowait_failed) { 238 /* 239 * XXX realisticly, this is what our 240 * nowait callers probably care about 241 */ 242 constraint = dma_constraint; 243 uvm_nowait_failed = 0; 244 } else 245 constraint = no_constraint; 246 } 247 248 uvm_unlock_fpageq(); 249 250 /* 251 * now lock page queues and recompute inactive count 252 */ 253 uvm_lock_pageq(); 254 if (npages != uvmexp.npages) { /* check for new pages? */ 255 npages = uvmexp.npages; 256 uvmpd_tune(); 257 } 258 259 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 260 if (uvmexp.inactarg <= uvmexp.freetarg) { 261 uvmexp.inactarg = uvmexp.freetarg + 1; 262 } 263 264 /* Reclaim pages from the buffer cache if possible. */ 265 size = 0; 266 if (pma != NULL) 267 size += pma->pm_size >> PAGE_SHIFT; 268 if (uvmexp.free - BUFPAGES_DEFICIT < uvmexp.freetarg) 269 size += uvmexp.freetarg - (uvmexp.free - 270 BUFPAGES_DEFICIT); 271 if (size == 0) 272 size = 16; /* XXX */ 273 uvm_unlock_pageq(); 274 (void) bufbackoff(&constraint, size * 2); 275 #if NDRM > 0 276 drmbackoff(size * 2); 277 #endif 278 uvm_lock_pageq(); 279 280 /* 281 * scan if needed 282 */ 283 if (pma != NULL || 284 ((uvmexp.free - BUFPAGES_DEFICIT) < uvmexp.freetarg) || 285 ((uvmexp.inactive + BUFPAGES_INACT) < uvmexp.inactarg)) { 286 uvmpd_scan(pma); 287 } 288 289 /* 290 * if there's any free memory to be had, 291 * wake up any waiters. 292 */ 293 uvm_lock_fpageq(); 294 if (uvmexp.free > uvmexp.reserve_kernel || 295 uvmexp.paging == 0) { 296 wakeup(&uvmexp.free); 297 } 298 299 if (pma != NULL) { 300 /* 301 * XXX If UVM_PMA_FREED isn't set, no pages 302 * were freed. Should we set UVM_PMA_FAIL in 303 * that case? 304 */ 305 pma->pm_flags &= ~UVM_PMA_BUSY; 306 if (pma->pm_flags & UVM_PMA_FREED) { 307 pma->pm_flags &= ~UVM_PMA_LINKED; 308 TAILQ_REMOVE(&uvm.pmr_control.allocs, pma, 309 pmq); 310 wakeup(pma); 311 } 312 } 313 uvm_unlock_fpageq(); 314 315 /* 316 * scan done. unlock page queues (the only lock we are holding) 317 */ 318 uvm_unlock_pageq(); 319 320 sched_pause(yield); 321 } 322 /*NOTREACHED*/ 323 } 324 325 326 /* 327 * uvm_aiodone_daemon: main loop for the aiodone daemon. 328 */ 329 void 330 uvm_aiodone_daemon(void *arg) 331 { 332 int s, free; 333 struct buf *bp, *nbp; 334 335 uvm.aiodoned_proc = curproc; 336 337 for (;;) { 338 /* 339 * Check for done aio structures. If we've got structures to 340 * process, do so. Otherwise sleep while avoiding races. 341 */ 342 mtx_enter(&uvm.aiodoned_lock); 343 while ((bp = TAILQ_FIRST(&uvm.aio_done)) == NULL) 344 msleep_nsec(&uvm.aiodoned, &uvm.aiodoned_lock, 345 PVM, "aiodoned", INFSLP); 346 /* Take the list for ourselves. */ 347 TAILQ_INIT(&uvm.aio_done); 348 mtx_leave(&uvm.aiodoned_lock); 349 350 /* process each i/o that's done. */ 351 free = uvmexp.free; 352 while (bp != NULL) { 353 if (bp->b_flags & B_PDAEMON) { 354 uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT; 355 } 356 nbp = TAILQ_NEXT(bp, b_freelist); 357 s = splbio(); /* b_iodone must by called at splbio */ 358 (*bp->b_iodone)(bp); 359 splx(s); 360 bp = nbp; 361 362 sched_pause(yield); 363 } 364 uvm_lock_fpageq(); 365 wakeup(free <= uvmexp.reserve_kernel ? &uvm.pagedaemon : 366 &uvmexp.free); 367 uvm_unlock_fpageq(); 368 } 369 } 370 371 /* 372 * uvmpd_trylockowner: trylock the page's owner. 373 * 374 * => return the locked rwlock on success. otherwise, return NULL. 375 */ 376 struct rwlock * 377 uvmpd_trylockowner(struct vm_page *pg) 378 { 379 380 struct uvm_object *uobj = pg->uobject; 381 struct rwlock *slock; 382 383 if (uobj != NULL) { 384 slock = uobj->vmobjlock; 385 } else { 386 struct vm_anon *anon = pg->uanon; 387 388 KASSERT(anon != NULL); 389 slock = anon->an_lock; 390 } 391 392 if (rw_enter(slock, RW_WRITE|RW_NOSLEEP)) { 393 return NULL; 394 } 395 396 return slock; 397 } 398 399 400 /* 401 * uvmpd_dropswap: free any swap allocated to this page. 402 * 403 * => called with owner locked. 404 */ 405 void 406 uvmpd_dropswap(struct vm_page *pg) 407 { 408 struct vm_anon *anon = pg->uanon; 409 410 if ((pg->pg_flags & PQ_ANON) && anon->an_swslot) { 411 uvm_swap_free(anon->an_swslot, 1); 412 anon->an_swslot = 0; 413 } else if (pg->pg_flags & PQ_AOBJ) { 414 uao_dropswap(pg->uobject, pg->offset >> PAGE_SHIFT); 415 } 416 } 417 418 /* 419 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 420 * 421 * => called with page queues locked 422 * => we work on meeting our free target by converting inactive pages 423 * into free pages. 424 * => we handle the building of swap-backed clusters 425 * => we return TRUE if we are exiting because we met our target 426 */ 427 void 428 uvmpd_scan_inactive(struct uvm_pmalloc *pma, struct pglist *pglst) 429 { 430 int free, result; 431 struct vm_page *p, *nextpg; 432 struct uvm_object *uobj; 433 struct vm_page *pps[SWCLUSTPAGES], **ppsp; 434 int npages; 435 struct vm_page *swpps[SWCLUSTPAGES]; /* XXX: see below */ 436 struct rwlock *slock; 437 int swnpages, swcpages; /* XXX: see below */ 438 int swslot; 439 struct vm_anon *anon; 440 boolean_t swap_backed; 441 vaddr_t start; 442 int dirtyreacts; 443 444 /* 445 * swslot is non-zero if we are building a swap cluster. we want 446 * to stay in the loop while we have a page to scan or we have 447 * a swap-cluster to build. 448 */ 449 swslot = 0; 450 swnpages = swcpages = 0; 451 dirtyreacts = 0; 452 p = NULL; 453 454 /* Start with the first page on the list that fit in pma's ranges */ 455 if (pma != NULL) { 456 paddr_t paddr; 457 458 TAILQ_FOREACH(p, pglst, pageq) { 459 paddr = atop(VM_PAGE_TO_PHYS(p)); 460 if (paddr >= pma->pm_constraint.ucr_low && 461 paddr < pma->pm_constraint.ucr_high) 462 break; 463 } 464 465 } 466 467 if (p == NULL) { 468 p = TAILQ_FIRST(pglst); 469 pma = NULL; 470 } 471 472 for (; p != NULL || swslot != 0; p = nextpg) { 473 /* 474 * note that p can be NULL iff we have traversed the whole 475 * list and need to do one final swap-backed clustered pageout. 476 */ 477 uobj = NULL; 478 anon = NULL; 479 if (p) { 480 /* 481 * see if we've met our target 482 */ 483 free = uvmexp.free - BUFPAGES_DEFICIT; 484 if (((pma == NULL || (pma->pm_flags & UVM_PMA_FREED)) && 485 (free + uvmexp.paging >= uvmexp.freetarg << 2)) || 486 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 487 if (swslot == 0) { 488 /* exit now if no swap-i/o pending */ 489 break; 490 } 491 492 /* set p to null to signal final swap i/o */ 493 p = NULL; 494 nextpg = NULL; 495 } 496 } 497 if (p) { /* if (we have a new page to consider) */ 498 /* 499 * we are below target and have a new page to consider. 500 */ 501 uvmexp.pdscans++; 502 nextpg = TAILQ_NEXT(p, pageq); 503 504 anon = p->uanon; 505 uobj = p->uobject; 506 507 /* 508 * first we attempt to lock the object that this page 509 * belongs to. if our attempt fails we skip on to 510 * the next page (no harm done). it is important to 511 * "try" locking the object as we are locking in the 512 * wrong order (pageq -> object) and we don't want to 513 * deadlock. 514 */ 515 slock = uvmpd_trylockowner(p); 516 if (slock == NULL) { 517 continue; 518 } 519 520 /* 521 * move referenced pages back to active queue 522 * and skip to next page. 523 */ 524 if (pmap_is_referenced(p)) { 525 uvm_pageactivate(p); 526 rw_exit(slock); 527 uvmexp.pdreact++; 528 continue; 529 } 530 531 if (p->pg_flags & PG_BUSY) { 532 rw_exit(slock); 533 uvmexp.pdbusy++; 534 continue; 535 } 536 537 /* does the page belong to an object? */ 538 if (uobj != NULL) { 539 uvmexp.pdobscan++; 540 } else { 541 KASSERT(anon != NULL); 542 uvmexp.pdanscan++; 543 } 544 545 /* 546 * we now have the page queues locked. 547 * the page is not busy. if the page is clean we 548 * can free it now and continue. 549 */ 550 if (p->pg_flags & PG_CLEAN) { 551 if (p->pg_flags & PQ_SWAPBACKED) { 552 /* this page now lives only in swap */ 553 atomic_inc_int(&uvmexp.swpgonly); 554 } 555 556 /* zap all mappings with pmap_page_protect... */ 557 pmap_page_protect(p, PROT_NONE); 558 uvm_pagefree(p); 559 uvmexp.pdfreed++; 560 561 if (anon) { 562 563 /* 564 * an anonymous page can only be clean 565 * if it has backing store assigned. 566 */ 567 568 KASSERT(anon->an_swslot != 0); 569 570 /* remove from object */ 571 anon->an_page = NULL; 572 } 573 rw_exit(slock); 574 continue; 575 } 576 577 /* 578 * this page is dirty, skip it if we'll have met our 579 * free target when all the current pageouts complete. 580 */ 581 if ((pma == NULL || (pma->pm_flags & UVM_PMA_FREED)) && 582 (free + uvmexp.paging > uvmexp.freetarg << 2)) { 583 rw_exit(slock); 584 continue; 585 } 586 587 /* 588 * this page is dirty, but we can't page it out 589 * since all pages in swap are only in swap. 590 * reactivate it so that we eventually cycle 591 * all pages thru the inactive queue. 592 */ 593 if ((p->pg_flags & PQ_SWAPBACKED) && uvm_swapisfull()) { 594 dirtyreacts++; 595 uvm_pageactivate(p); 596 rw_exit(slock); 597 continue; 598 } 599 600 /* 601 * if the page is swap-backed and dirty and swap space 602 * is full, free any swap allocated to the page 603 * so that other pages can be paged out. 604 */ 605 KASSERT(uvmexp.swpginuse <= uvmexp.swpages); 606 if ((p->pg_flags & PQ_SWAPBACKED) && 607 uvmexp.swpginuse == uvmexp.swpages) { 608 uvmpd_dropswap(p); 609 } 610 611 /* 612 * the page we are looking at is dirty. we must 613 * clean it before it can be freed. to do this we 614 * first mark the page busy so that no one else will 615 * touch the page. we write protect all the mappings 616 * of the page so that no one touches it while it is 617 * in I/O. 618 */ 619 620 swap_backed = ((p->pg_flags & PQ_SWAPBACKED) != 0); 621 atomic_setbits_int(&p->pg_flags, PG_BUSY); 622 UVM_PAGE_OWN(p, "scan_inactive"); 623 pmap_page_protect(p, PROT_READ); 624 uvmexp.pgswapout++; 625 626 /* 627 * for swap-backed pages we need to (re)allocate 628 * swap space. 629 */ 630 if (swap_backed) { 631 /* free old swap slot (if any) */ 632 uvmpd_dropswap(p); 633 634 /* start new cluster (if necessary) */ 635 if (swslot == 0) { 636 swnpages = SWCLUSTPAGES; 637 swslot = uvm_swap_alloc(&swnpages, 638 TRUE); 639 if (swslot == 0) { 640 /* no swap? give up! */ 641 atomic_clearbits_int( 642 &p->pg_flags, 643 PG_BUSY); 644 UVM_PAGE_OWN(p, NULL); 645 rw_exit(slock); 646 continue; 647 } 648 swcpages = 0; /* cluster is empty */ 649 } 650 651 /* add block to cluster */ 652 swpps[swcpages] = p; 653 if (anon) 654 anon->an_swslot = swslot + swcpages; 655 else 656 uao_set_swslot(uobj, 657 p->offset >> PAGE_SHIFT, 658 swslot + swcpages); 659 swcpages++; 660 } 661 } else { 662 /* if p == NULL we must be doing a last swap i/o */ 663 swap_backed = TRUE; 664 } 665 666 /* 667 * now consider doing the pageout. 668 * 669 * for swap-backed pages, we do the pageout if we have either 670 * filled the cluster (in which case (swnpages == swcpages) or 671 * run out of pages (p == NULL). 672 * 673 * for object pages, we always do the pageout. 674 */ 675 if (swap_backed) { 676 if (p) { /* if we just added a page to cluster */ 677 rw_exit(slock); 678 679 /* cluster not full yet? */ 680 if (swcpages < swnpages) 681 continue; 682 } 683 684 /* starting I/O now... set up for it */ 685 npages = swcpages; 686 ppsp = swpps; 687 /* for swap-backed pages only */ 688 start = (vaddr_t) swslot; 689 690 /* if this is final pageout we could have a few 691 * extra swap blocks */ 692 if (swcpages < swnpages) { 693 uvm_swap_free(swslot + swcpages, 694 (swnpages - swcpages)); 695 } 696 } else { 697 /* normal object pageout */ 698 ppsp = pps; 699 npages = sizeof(pps) / sizeof(struct vm_page *); 700 /* not looked at because PGO_ALLPAGES is set */ 701 start = 0; 702 } 703 704 /* 705 * now do the pageout. 706 * 707 * for swap_backed pages we have already built the cluster. 708 * for !swap_backed pages, uvm_pager_put will call the object's 709 * "make put cluster" function to build a cluster on our behalf. 710 * 711 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 712 * it to free the cluster pages for us on a successful I/O (it 713 * always does this for un-successful I/O requests). this 714 * allows us to do clustered pageout without having to deal 715 * with cluster pages at this level. 716 * 717 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 718 * IN: locked: page queues 719 * OUT: locked: 720 * !locked: pageqs 721 */ 722 723 uvmexp.pdpageouts++; 724 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 725 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 726 727 /* 728 * if we did i/o to swap, zero swslot to indicate that we are 729 * no longer building a swap-backed cluster. 730 */ 731 732 if (swap_backed) 733 swslot = 0; /* done with this cluster */ 734 735 /* 736 * first, we check for VM_PAGER_PEND which means that the 737 * async I/O is in progress and the async I/O done routine 738 * will clean up after us. in this case we move on to the 739 * next page. 740 * 741 * there is a very remote chance that the pending async i/o can 742 * finish _before_ we get here. if that happens, our page "p" 743 * may no longer be on the inactive queue. so we verify this 744 * when determining the next page (starting over at the head if 745 * we've lost our inactive page). 746 */ 747 748 if (result == VM_PAGER_PEND) { 749 uvmexp.paging += npages; 750 uvm_lock_pageq(); 751 uvmexp.pdpending++; 752 if (p) { 753 if (p->pg_flags & PQ_INACTIVE) 754 nextpg = TAILQ_NEXT(p, pageq); 755 else 756 nextpg = TAILQ_FIRST(pglst); 757 } else { 758 nextpg = NULL; 759 } 760 continue; 761 } 762 763 /* clean up "p" if we have one */ 764 if (p) { 765 /* 766 * the I/O request to "p" is done and uvm_pager_put 767 * has freed any cluster pages it may have allocated 768 * during I/O. all that is left for us to do is 769 * clean up page "p" (which is still PG_BUSY). 770 * 771 * our result could be one of the following: 772 * VM_PAGER_OK: successful pageout 773 * 774 * VM_PAGER_AGAIN: tmp resource shortage, we skip 775 * to next page 776 * VM_PAGER_{FAIL,ERROR,BAD}: an error. we 777 * "reactivate" page to get it out of the way (it 778 * will eventually drift back into the inactive 779 * queue for a retry). 780 * VM_PAGER_UNLOCK: should never see this as it is 781 * only valid for "get" operations 782 */ 783 784 /* relock p's object: page queues not lock yet, so 785 * no need for "try" */ 786 787 /* !swap_backed case: already locked... */ 788 if (swap_backed) { 789 rw_enter(slock, RW_WRITE); 790 } 791 792 #ifdef DIAGNOSTIC 793 if (result == VM_PAGER_UNLOCK) 794 panic("pagedaemon: pageout returned " 795 "invalid 'unlock' code"); 796 #endif 797 798 /* handle PG_WANTED now */ 799 if (p->pg_flags & PG_WANTED) 800 wakeup(p); 801 802 atomic_clearbits_int(&p->pg_flags, PG_BUSY|PG_WANTED); 803 UVM_PAGE_OWN(p, NULL); 804 805 /* released during I/O? Can only happen for anons */ 806 if (p->pg_flags & PG_RELEASED) { 807 KASSERT(anon != NULL); 808 /* 809 * remove page so we can get nextpg, 810 * also zero out anon so we don't use 811 * it after the free. 812 */ 813 anon->an_page = NULL; 814 p->uanon = NULL; 815 816 rw_exit(anon->an_lock); 817 uvm_anfree(anon); /* kills anon */ 818 pmap_page_protect(p, PROT_NONE); 819 anon = NULL; 820 uvm_lock_pageq(); 821 nextpg = TAILQ_NEXT(p, pageq); 822 /* free released page */ 823 uvm_pagefree(p); 824 } else { /* page was not released during I/O */ 825 uvm_lock_pageq(); 826 nextpg = TAILQ_NEXT(p, pageq); 827 if (result != VM_PAGER_OK) { 828 /* pageout was a failure... */ 829 if (result != VM_PAGER_AGAIN) 830 uvm_pageactivate(p); 831 pmap_clear_reference(p); 832 /* XXXCDC: if (swap_backed) FREE p's 833 * swap block? */ 834 } else { 835 /* pageout was a success... */ 836 pmap_clear_reference(p); 837 pmap_clear_modify(p); 838 atomic_setbits_int(&p->pg_flags, 839 PG_CLEAN); 840 } 841 } 842 843 /* 844 * drop object lock (if there is an object left). do 845 * a safety check of nextpg to make sure it is on the 846 * inactive queue (it should be since PG_BUSY pages on 847 * the inactive queue can't be re-queued [note: not 848 * true for active queue]). 849 */ 850 rw_exit(slock); 851 852 if (nextpg && (nextpg->pg_flags & PQ_INACTIVE) == 0) { 853 nextpg = TAILQ_FIRST(pglst); /* reload! */ 854 } 855 } else { 856 /* 857 * if p is null in this loop, make sure it stays null 858 * in the next loop. 859 */ 860 nextpg = NULL; 861 862 /* 863 * lock page queues here just so they're always locked 864 * at the end of the loop. 865 */ 866 uvm_lock_pageq(); 867 } 868 } 869 } 870 871 /* 872 * uvmpd_scan: scan the page queues and attempt to meet our targets. 873 * 874 * => called with pageq's locked 875 */ 876 877 void 878 uvmpd_scan(struct uvm_pmalloc *pma) 879 { 880 int free, inactive_shortage, swap_shortage, pages_freed; 881 struct vm_page *p, *nextpg; 882 struct rwlock *slock; 883 884 MUTEX_ASSERT_LOCKED(&uvm.pageqlock); 885 886 uvmexp.pdrevs++; /* counter */ 887 888 /* 889 * get current "free" page count 890 */ 891 free = uvmexp.free - BUFPAGES_DEFICIT; 892 893 #ifdef __HAVE_PMAP_COLLECT 894 /* 895 * swap out some processes if we are below our free target. 896 * we need to unlock the page queues for this. 897 */ 898 if (free < uvmexp.freetarg) { 899 uvmexp.pdswout++; 900 uvm_unlock_pageq(); 901 uvm_swapout_threads(); 902 uvm_lock_pageq(); 903 } 904 #endif 905 906 /* 907 * now we want to work on meeting our targets. first we work on our 908 * free target by converting inactive pages into free pages. then 909 * we work on meeting our inactive target by converting active pages 910 * to inactive ones. 911 */ 912 913 pages_freed = uvmexp.pdfreed; 914 (void) uvmpd_scan_inactive(pma, &uvm.page_inactive); 915 pages_freed = uvmexp.pdfreed - pages_freed; 916 917 /* 918 * we have done the scan to get free pages. now we work on meeting 919 * our inactive target. 920 */ 921 inactive_shortage = uvmexp.inactarg - uvmexp.inactive - BUFPAGES_INACT; 922 923 /* 924 * detect if we're not going to be able to page anything out 925 * until we free some swap resources from active pages. 926 */ 927 free = uvmexp.free - BUFPAGES_DEFICIT; 928 swap_shortage = 0; 929 if (free < uvmexp.freetarg && 930 uvmexp.swpginuse == uvmexp.swpages && 931 !uvm_swapisfull() && 932 pages_freed == 0) { 933 swap_shortage = uvmexp.freetarg - free; 934 } 935 936 for (p = TAILQ_FIRST(&uvm.page_active); 937 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 938 p = nextpg) { 939 nextpg = TAILQ_NEXT(p, pageq); 940 if (p->pg_flags & PG_BUSY) { 941 continue; 942 } 943 944 /* 945 * lock the page's owner. 946 */ 947 slock = uvmpd_trylockowner(p); 948 if (slock == NULL) { 949 continue; 950 } 951 952 /* 953 * skip this page if it's busy. 954 */ 955 if ((p->pg_flags & PG_BUSY) != 0) { 956 rw_exit(slock); 957 continue; 958 } 959 960 /* 961 * if there's a shortage of swap, free any swap allocated 962 * to this page so that other pages can be paged out. 963 */ 964 if (swap_shortage > 0) { 965 if ((p->pg_flags & PQ_ANON) && p->uanon->an_swslot) { 966 uvm_swap_free(p->uanon->an_swslot, 1); 967 p->uanon->an_swslot = 0; 968 atomic_clearbits_int(&p->pg_flags, PG_CLEAN); 969 swap_shortage--; 970 } 971 if (p->pg_flags & PQ_AOBJ) { 972 int slot = uao_set_swslot(p->uobject, 973 p->offset >> PAGE_SHIFT, 0); 974 if (slot) { 975 uvm_swap_free(slot, 1); 976 atomic_clearbits_int(&p->pg_flags, 977 PG_CLEAN); 978 swap_shortage--; 979 } 980 } 981 } 982 983 /* 984 * deactivate this page if there's a shortage of 985 * inactive pages. 986 */ 987 if (inactive_shortage > 0) { 988 pmap_page_protect(p, PROT_NONE); 989 /* no need to check wire_count as pg is "active" */ 990 uvm_pagedeactivate(p); 991 uvmexp.pddeact++; 992 inactive_shortage--; 993 } 994 995 /* 996 * we're done with this page. 997 */ 998 rw_exit(slock); 999 } 1000 } 1001 1002 #ifdef HIBERNATE 1003 1004 /* 1005 * uvmpd_drop: drop clean pages from list 1006 */ 1007 void 1008 uvmpd_drop(struct pglist *pglst) 1009 { 1010 struct vm_page *p, *nextpg; 1011 1012 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 1013 nextpg = TAILQ_NEXT(p, pageq); 1014 1015 if (p->pg_flags & PQ_ANON || p->uobject == NULL) 1016 continue; 1017 1018 if (p->pg_flags & PG_BUSY) 1019 continue; 1020 1021 if (p->pg_flags & PG_CLEAN) { 1022 struct uvm_object * uobj = p->uobject; 1023 1024 rw_enter(uobj->vmobjlock, RW_WRITE); 1025 uvm_lock_pageq(); 1026 /* 1027 * we now have the page queues locked. 1028 * the page is not busy. if the page is clean we 1029 * can free it now and continue. 1030 */ 1031 if (p->pg_flags & PG_CLEAN) { 1032 if (p->pg_flags & PQ_SWAPBACKED) { 1033 /* this page now lives only in swap */ 1034 atomic_inc_int(&uvmexp.swpgonly); 1035 } 1036 1037 /* zap all mappings with pmap_page_protect... */ 1038 pmap_page_protect(p, PROT_NONE); 1039 uvm_pagefree(p); 1040 } 1041 uvm_unlock_pageq(); 1042 rw_exit(uobj->vmobjlock); 1043 } 1044 } 1045 } 1046 1047 void 1048 uvmpd_hibernate(void) 1049 { 1050 uvmpd_drop(&uvm.page_inactive); 1051 uvmpd_drop(&uvm.page_active); 1052 } 1053 1054 #endif 1055