1 /* $OpenBSD: uvm_pdaemon.c,v 1.134 2025/01/25 08:55:52 mpi 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 unsigned long 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 *, int, int); 106 int uvmpd_scan_inactive(struct uvm_pmalloc *, int); 107 void uvmpd_scan_active(struct uvm_pmalloc *, int, int); 108 void uvmpd_tune(void); 109 void uvmpd_drop(struct pglist *); 110 int uvmpd_dropswap(struct vm_page *); 111 112 /* 113 * uvm_wait: wait (sleep) for the page daemon to free some pages 114 * 115 * => should be called with all locks released 116 * => should _not_ be called by the page daemon (to avoid deadlock) 117 */ 118 119 void 120 uvm_wait(const char *wmsg) 121 { 122 uint64_t timo = INFSLP; 123 124 #ifdef DIAGNOSTIC 125 if (curproc == &proc0) 126 panic("%s: cannot sleep for memory during boot", __func__); 127 #endif 128 129 /* 130 * check for page daemon going to sleep (waiting for itself) 131 */ 132 if (curproc == uvm.pagedaemon_proc) { 133 printf("uvm_wait emergency bufbackoff\n"); 134 if (bufbackoff(NULL, 4) >= 4) 135 return; 136 /* 137 * now we have a problem: the pagedaemon wants to go to 138 * sleep until it frees more memory. but how can it 139 * free more memory if it is asleep? that is a deadlock. 140 * we have two options: 141 * [1] panic now 142 * [2] put a timeout on the sleep, thus causing the 143 * pagedaemon to only pause (rather than sleep forever) 144 * 145 * note that option [2] will only help us if we get lucky 146 * and some other process on the system breaks the deadlock 147 * by exiting or freeing memory (thus allowing the pagedaemon 148 * to continue). for now we panic if DEBUG is defined, 149 * otherwise we hope for the best with option [2] (better 150 * yet, this should never happen in the first place!). 151 */ 152 153 printf("pagedaemon: deadlock detected!\n"); 154 timo = MSEC_TO_NSEC(125); /* set timeout */ 155 #if defined(DEBUG) 156 /* DEBUG: panic so we can debug it */ 157 panic("pagedaemon deadlock"); 158 #endif 159 } 160 161 uvm_lock_fpageq(); 162 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 163 msleep_nsec(&uvmexp.free, &uvm.fpageqlock, PVM | PNORELOCK, wmsg, timo); 164 } 165 166 /* 167 * uvmpd_tune: tune paging parameters 168 */ 169 void 170 uvmpd_tune(void) 171 { 172 int val; 173 174 val = uvmexp.npages / 30; 175 176 /* XXX: what are these values good for? */ 177 val = max(val, (16*1024) >> PAGE_SHIFT); 178 179 /* Make sure there's always a user page free. */ 180 if (val < uvmexp.reserve_kernel + 1) 181 val = uvmexp.reserve_kernel + 1; 182 uvmexp.freemin = val; 183 184 /* Calculate free target. */ 185 val = (uvmexp.freemin * 4) / 3; 186 if (val <= uvmexp.freemin) 187 val = uvmexp.freemin + 1; 188 uvmexp.freetarg = val; 189 190 uvmexp.wiredmax = uvmexp.npages / 3; 191 } 192 193 /* 194 * Indicate to the page daemon that a nowait call failed and it should 195 * recover at least some memory in the most restricted region (assumed 196 * to be dma_constraint). 197 */ 198 struct uvm_pmalloc nowait_pma; 199 200 static inline int 201 uvmpd_pma_done(struct uvm_pmalloc *pma) 202 { 203 if (pma == NULL || (pma->pm_flags & UVM_PMA_FREED)) 204 return 1; 205 return 0; 206 } 207 208 /* 209 * uvm_pageout: the main loop for the pagedaemon 210 */ 211 void 212 uvm_pageout(void *arg) 213 { 214 struct uvm_constraint_range constraint; 215 struct uvm_pmalloc *pma; 216 int shortage, inactive_shortage; 217 218 /* ensure correct priority and set paging parameters... */ 219 uvm.pagedaemon_proc = curproc; 220 (void) spl0(); 221 uvmpd_tune(); 222 223 /* 224 * XXX realistically, this is what our nowait callers probably 225 * care about. 226 */ 227 nowait_pma.pm_constraint = dma_constraint; 228 nowait_pma.pm_size = (16 << PAGE_SHIFT); /* XXX */ 229 nowait_pma.pm_flags = 0; 230 231 for (;;) { 232 long size; 233 234 uvm_lock_fpageq(); 235 if (TAILQ_EMPTY(&uvm.pmr_control.allocs) || uvmexp.paging > 0) { 236 msleep_nsec(&uvm.pagedaemon, &uvm.fpageqlock, PVM, 237 "pgdaemon", INFSLP); 238 uvmexp.pdwoke++; 239 } 240 241 if ((pma = TAILQ_FIRST(&uvm.pmr_control.allocs)) != NULL) { 242 pma->pm_flags |= UVM_PMA_BUSY; 243 constraint = pma->pm_constraint; 244 } else { 245 constraint = no_constraint; 246 } 247 /* How many pages do we need to free during this round? */ 248 shortage = uvmexp.freetarg - 249 (uvmexp.free + uvmexp.paging) + BUFPAGES_DEFICIT; 250 uvm_unlock_fpageq(); 251 252 /* 253 * now lock page queues and recompute inactive count 254 */ 255 uvm_lock_pageq(); 256 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 257 if (uvmexp.inactarg <= uvmexp.freetarg) { 258 uvmexp.inactarg = uvmexp.freetarg + 1; 259 } 260 inactive_shortage = 261 uvmexp.inactarg - uvmexp.inactive - BUFPAGES_INACT; 262 uvm_unlock_pageq(); 263 264 size = 0; 265 if (pma != NULL) 266 size += pma->pm_size >> PAGE_SHIFT; 267 if (shortage > 0) 268 size += shortage; 269 270 if (size == 0) { 271 /* 272 * Since the inactive target just got updated 273 * above, both `size' and `inactive_shortage' can 274 * be 0. 275 */ 276 if (inactive_shortage) { 277 uvm_lock_pageq(); 278 uvmpd_scan_active(NULL, 0, inactive_shortage); 279 uvm_unlock_pageq(); 280 } 281 continue; 282 } 283 284 /* Reclaim pages from the buffer cache if possible. */ 285 shortage -= bufbackoff(&constraint, size * 2); 286 #if NDRM > 0 287 shortage -= drmbackoff(size * 2); 288 #endif 289 if (shortage > 0) 290 shortage -= uvm_pmr_cache_drain(); 291 292 /* 293 * scan if needed 294 */ 295 uvm_lock_pageq(); 296 if (!uvmpd_pma_done(pma) || 297 (shortage > 0) || (inactive_shortage > 0)) { 298 uvmpd_scan(pma, shortage, inactive_shortage); 299 } 300 301 /* 302 * if there's any free memory to be had, 303 * wake up any waiters. 304 */ 305 uvm_lock_fpageq(); 306 if (uvmexp.free > uvmexp.reserve_kernel || uvmexp.paging == 0) { 307 wakeup(&uvmexp.free); 308 } 309 310 if (pma != NULL) { 311 /* 312 * XXX If UVM_PMA_FREED isn't set, no pages 313 * were freed. Should we set UVM_PMA_FAIL in 314 * that case? 315 */ 316 pma->pm_flags &= ~UVM_PMA_BUSY; 317 if (pma->pm_flags & UVM_PMA_FREED) { 318 pma->pm_flags &= ~UVM_PMA_LINKED; 319 TAILQ_REMOVE(&uvm.pmr_control.allocs, pma, pmq); 320 wakeup(pma); 321 } 322 } 323 uvm_unlock_fpageq(); 324 325 /* 326 * scan done. unlock page queues (the only lock we are holding) 327 */ 328 uvm_unlock_pageq(); 329 330 sched_pause(yield); 331 } 332 /*NOTREACHED*/ 333 } 334 335 336 /* 337 * uvm_aiodone_daemon: main loop for the aiodone daemon. 338 */ 339 void 340 uvm_aiodone_daemon(void *arg) 341 { 342 int s, npages; 343 struct buf *bp, *nbp; 344 345 uvm.aiodoned_proc = curproc; 346 KERNEL_UNLOCK(); 347 348 for (;;) { 349 /* 350 * Check for done aio structures. If we've got structures to 351 * process, do so. Otherwise sleep while avoiding races. 352 */ 353 mtx_enter(&uvm.aiodoned_lock); 354 while ((bp = TAILQ_FIRST(&uvm.aio_done)) == NULL) 355 msleep_nsec(&uvm.aiodoned, &uvm.aiodoned_lock, 356 PVM, "aiodoned", INFSLP); 357 /* Take the list for ourselves. */ 358 TAILQ_INIT(&uvm.aio_done); 359 mtx_leave(&uvm.aiodoned_lock); 360 361 /* process each i/o that's done. */ 362 npages = 0; 363 KERNEL_LOCK(); 364 while (bp != NULL) { 365 if (bp->b_flags & B_PDAEMON) { 366 npages += bp->b_bufsize >> PAGE_SHIFT; 367 } 368 nbp = TAILQ_NEXT(bp, b_freelist); 369 s = splbio(); /* b_iodone must by called at splbio */ 370 (*bp->b_iodone)(bp); 371 splx(s); 372 bp = nbp; 373 374 sched_pause(yield); 375 } 376 KERNEL_UNLOCK(); 377 378 uvm_lock_fpageq(); 379 atomic_sub_int(&uvmexp.paging, npages); 380 wakeup(uvmexp.free <= uvmexp.reserve_kernel ? &uvm.pagedaemon : 381 &uvmexp.free); 382 uvm_unlock_fpageq(); 383 } 384 } 385 386 /* 387 * uvmpd_trylockowner: trylock the page's owner. 388 * 389 * => return the locked rwlock on success. otherwise, return NULL. 390 */ 391 struct rwlock * 392 uvmpd_trylockowner(struct vm_page *pg) 393 { 394 395 struct uvm_object *uobj = pg->uobject; 396 struct rwlock *slock; 397 398 if (uobj != NULL) { 399 slock = uobj->vmobjlock; 400 } else { 401 struct vm_anon *anon = pg->uanon; 402 403 KASSERT(anon != NULL); 404 slock = anon->an_lock; 405 } 406 407 if (rw_enter(slock, RW_WRITE|RW_NOSLEEP)) { 408 return NULL; 409 } 410 411 return slock; 412 } 413 414 /* 415 * uvmpd_dropswap: free any swap allocated to this page. 416 * 417 * => called with owner locked. 418 * => return 1 if a page had an associated slot. 419 */ 420 int 421 uvmpd_dropswap(struct vm_page *pg) 422 { 423 struct vm_anon *anon = pg->uanon; 424 int slot, result = 0; 425 426 if ((pg->pg_flags & PQ_ANON) && anon->an_swslot) { 427 uvm_swap_free(anon->an_swslot, 1); 428 anon->an_swslot = 0; 429 result = 1; 430 } else if (pg->pg_flags & PQ_AOBJ) { 431 slot = uao_dropswap(pg->uobject, pg->offset >> PAGE_SHIFT); 432 if (slot) 433 result = 1; 434 } 435 436 return result; 437 } 438 439 /* 440 * Return 1 if the page `p' belongs to the memory range described by 441 * 'constraint', 0 otherwise. 442 */ 443 static inline int 444 uvmpd_match_constraint(struct vm_page *p, 445 struct uvm_constraint_range *constraint) 446 { 447 paddr_t paddr; 448 449 paddr = atop(VM_PAGE_TO_PHYS(p)); 450 if (paddr >= constraint->ucr_low && paddr < constraint->ucr_high) 451 return 1; 452 453 return 0; 454 } 455 456 /* 457 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 458 * 459 * => called with page queues locked 460 * => we work on meeting our free target by converting inactive pages 461 * into free pages. 462 * => we handle the building of swap-backed clusters 463 * => we return TRUE if we are exiting because we met our target 464 */ 465 int 466 uvmpd_scan_inactive(struct uvm_pmalloc *pma, int shortage) 467 { 468 struct pglist *pglst = &uvm.page_inactive; 469 int result, freed = 0; 470 struct vm_page *p, *nextpg; 471 struct uvm_object *uobj; 472 struct vm_page *pps[SWCLUSTPAGES], **ppsp; 473 int npages; 474 struct vm_page *swpps[SWCLUSTPAGES]; /* XXX: see below */ 475 struct rwlock *slock; 476 int swnpages, swcpages; /* XXX: see below */ 477 int swslot; 478 struct vm_anon *anon; 479 boolean_t swap_backed; 480 vaddr_t start; 481 int dirtyreacts; 482 483 /* 484 * swslot is non-zero if we are building a swap cluster. we want 485 * to stay in the loop while we have a page to scan or we have 486 * a swap-cluster to build. 487 */ 488 swslot = 0; 489 swnpages = swcpages = 0; 490 dirtyreacts = 0; 491 p = NULL; 492 493 /* 494 * If a thread is waiting for us to release memory from a specific 495 * memory range start with the first page on the list that fits in 496 * it. 497 */ 498 TAILQ_FOREACH(p, pglst, pageq) { 499 if (uvmpd_pma_done(pma) || 500 uvmpd_match_constraint(p, &pma->pm_constraint)) 501 break; 502 } 503 504 for (; p != NULL || swslot != 0; p = nextpg) { 505 /* 506 * note that p can be NULL iff we have traversed the whole 507 * list and need to do one final swap-backed clustered pageout. 508 */ 509 uobj = NULL; 510 anon = NULL; 511 if (p) { 512 /* 513 * see if we've met our target 514 */ 515 if ((uvmpd_pma_done(pma) && 516 (uvmexp.paging >= (shortage - freed))) || 517 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 518 if (swslot == 0) { 519 /* exit now if no swap-i/o pending */ 520 break; 521 } 522 523 /* set p to null to signal final swap i/o */ 524 p = NULL; 525 nextpg = NULL; 526 } 527 } 528 if (p) { /* if (we have a new page to consider) */ 529 /* 530 * we are below target and have a new page to consider. 531 */ 532 uvmexp.pdscans++; 533 nextpg = TAILQ_NEXT(p, pageq); 534 535 /* 536 * If we are not short on memory and only interested 537 * in releasing pages from a given memory range, do not 538 * bother with other pages. 539 */ 540 if (uvmexp.paging >= (shortage - freed) && 541 !uvmpd_pma_done(pma) && 542 !uvmpd_match_constraint(p, &pma->pm_constraint)) 543 continue; 544 545 anon = p->uanon; 546 uobj = p->uobject; 547 548 /* 549 * first we attempt to lock the object that this page 550 * belongs to. if our attempt fails we skip on to 551 * the next page (no harm done). it is important to 552 * "try" locking the object as we are locking in the 553 * wrong order (pageq -> object) and we don't want to 554 * deadlock. 555 */ 556 slock = uvmpd_trylockowner(p); 557 if (slock == NULL) { 558 continue; 559 } 560 561 /* 562 * move referenced pages back to active queue 563 * and skip to next page. 564 */ 565 if (pmap_is_referenced(p)) { 566 uvm_pageactivate(p); 567 rw_exit(slock); 568 uvmexp.pdreact++; 569 continue; 570 } 571 572 if (p->pg_flags & PG_BUSY) { 573 rw_exit(slock); 574 uvmexp.pdbusy++; 575 continue; 576 } 577 578 /* does the page belong to an object? */ 579 if (uobj != NULL) { 580 uvmexp.pdobscan++; 581 } else { 582 KASSERT(anon != NULL); 583 uvmexp.pdanscan++; 584 } 585 586 /* 587 * we now have the page queues locked. 588 * the page is not busy. if the page is clean we 589 * can free it now and continue. 590 */ 591 if (p->pg_flags & PG_CLEAN) { 592 if (p->pg_flags & PQ_SWAPBACKED) { 593 /* this page now lives only in swap */ 594 atomic_inc_int(&uvmexp.swpgonly); 595 } 596 597 /* zap all mappings with pmap_page_protect... */ 598 pmap_page_protect(p, PROT_NONE); 599 uvm_pagefree(p); 600 freed++; 601 602 if (anon) { 603 604 /* 605 * an anonymous page can only be clean 606 * if it has backing store assigned. 607 */ 608 609 KASSERT(anon->an_swslot != 0); 610 611 /* remove from object */ 612 anon->an_page = NULL; 613 } 614 rw_exit(slock); 615 continue; 616 } 617 618 /* 619 * this page is dirty, skip it if we'll have met our 620 * free target when all the current pageouts complete. 621 */ 622 if (uvmpd_pma_done(pma) && 623 (uvmexp.paging > (shortage - freed))) { 624 rw_exit(slock); 625 continue; 626 } 627 628 /* 629 * this page is dirty, but we can't page it out 630 * since all pages in swap are only in swap. 631 * reactivate it so that we eventually cycle 632 * all pages thru the inactive queue. 633 */ 634 if ((p->pg_flags & PQ_SWAPBACKED) && uvm_swapisfull()) { 635 dirtyreacts++; 636 uvm_pageactivate(p); 637 rw_exit(slock); 638 continue; 639 } 640 641 /* 642 * if the page is swap-backed and dirty and swap space 643 * is full, free any swap allocated to the page 644 * so that other pages can be paged out. 645 */ 646 if ((p->pg_flags & PQ_SWAPBACKED) && uvm_swapisfilled()) 647 uvmpd_dropswap(p); 648 649 /* 650 * the page we are looking at is dirty. we must 651 * clean it before it can be freed. to do this we 652 * first mark the page busy so that no one else will 653 * touch the page. we write protect all the mappings 654 * of the page so that no one touches it while it is 655 * in I/O. 656 */ 657 658 swap_backed = ((p->pg_flags & PQ_SWAPBACKED) != 0); 659 atomic_setbits_int(&p->pg_flags, PG_BUSY); 660 UVM_PAGE_OWN(p, "scan_inactive"); 661 pmap_page_protect(p, PROT_READ); 662 uvmexp.pgswapout++; 663 664 /* 665 * for swap-backed pages we need to (re)allocate 666 * swap space. 667 */ 668 if (swap_backed) { 669 /* free old swap slot (if any) */ 670 uvmpd_dropswap(p); 671 672 /* start new cluster (if necessary) */ 673 if (swslot == 0) { 674 swnpages = SWCLUSTPAGES; 675 swslot = uvm_swap_alloc(&swnpages, 676 TRUE); 677 if (swslot == 0) { 678 /* no swap? give up! */ 679 atomic_clearbits_int( 680 &p->pg_flags, 681 PG_BUSY); 682 UVM_PAGE_OWN(p, NULL); 683 rw_exit(slock); 684 continue; 685 } 686 swcpages = 0; /* cluster is empty */ 687 } 688 689 /* add block to cluster */ 690 swpps[swcpages] = p; 691 if (anon) 692 anon->an_swslot = swslot + swcpages; 693 else 694 uao_set_swslot(uobj, 695 p->offset >> PAGE_SHIFT, 696 swslot + swcpages); 697 swcpages++; 698 rw_exit(slock); 699 700 /* cluster not full yet? */ 701 if (swcpages < swnpages) 702 continue; 703 } 704 } else { 705 /* if p == NULL we must be doing a last swap i/o */ 706 swap_backed = TRUE; 707 } 708 709 /* 710 * now consider doing the pageout. 711 * 712 * for swap-backed pages, we do the pageout if we have either 713 * filled the cluster (in which case (swnpages == swcpages) or 714 * run out of pages (p == NULL). 715 * 716 * for object pages, we always do the pageout. 717 */ 718 if (swap_backed) { 719 /* starting I/O now... set up for it */ 720 npages = swcpages; 721 ppsp = swpps; 722 /* for swap-backed pages only */ 723 start = (vaddr_t) swslot; 724 725 /* if this is final pageout we could have a few 726 * extra swap blocks */ 727 if (swcpages < swnpages) { 728 uvm_swap_free(swslot + swcpages, 729 (swnpages - swcpages)); 730 } 731 } else { 732 /* normal object pageout */ 733 ppsp = pps; 734 npages = sizeof(pps) / sizeof(struct vm_page *); 735 /* not looked at because PGO_ALLPAGES is set */ 736 start = 0; 737 } 738 739 /* 740 * now do the pageout. 741 * 742 * for swap_backed pages we have already built the cluster. 743 * for !swap_backed pages, uvm_pager_put will call the object's 744 * "make put cluster" function to build a cluster on our behalf. 745 * 746 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 747 * it to free the cluster pages for us on a successful I/O (it 748 * always does this for un-successful I/O requests). this 749 * allows us to do clustered pageout without having to deal 750 * with cluster pages at this level. 751 * 752 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 753 * IN: locked: page queues 754 * OUT: locked: 755 * !locked: pageqs 756 */ 757 758 uvmexp.pdpageouts++; 759 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 760 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 761 762 /* 763 * if we did i/o to swap, zero swslot to indicate that we are 764 * no longer building a swap-backed cluster. 765 */ 766 767 if (swap_backed) 768 swslot = 0; /* done with this cluster */ 769 770 /* 771 * first, we check for VM_PAGER_PEND which means that the 772 * async I/O is in progress and the async I/O done routine 773 * will clean up after us. in this case we move on to the 774 * next page. 775 * 776 * there is a very remote chance that the pending async i/o can 777 * finish _before_ we get here. if that happens, our page "p" 778 * may no longer be on the inactive queue. so we verify this 779 * when determining the next page (starting over at the head if 780 * we've lost our inactive page). 781 */ 782 783 if (result == VM_PAGER_PEND) { 784 atomic_add_int(&uvmexp.paging, npages); 785 uvm_lock_pageq(); 786 uvmexp.pdpending++; 787 if (p) { 788 if (p->pg_flags & PQ_INACTIVE) 789 nextpg = TAILQ_NEXT(p, pageq); 790 else 791 nextpg = TAILQ_FIRST(pglst); 792 } else { 793 nextpg = NULL; 794 } 795 continue; 796 } 797 798 /* clean up "p" if we have one */ 799 if (p) { 800 /* 801 * the I/O request to "p" is done and uvm_pager_put 802 * has freed any cluster pages it may have allocated 803 * during I/O. all that is left for us to do is 804 * clean up page "p" (which is still PG_BUSY). 805 * 806 * our result could be one of the following: 807 * VM_PAGER_OK: successful pageout 808 * 809 * VM_PAGER_AGAIN: tmp resource shortage, we skip 810 * to next page 811 * VM_PAGER_{FAIL,ERROR,BAD}: an error. we 812 * "reactivate" page to get it out of the way (it 813 * will eventually drift back into the inactive 814 * queue for a retry). 815 * VM_PAGER_UNLOCK: should never see this as it is 816 * only valid for "get" operations 817 */ 818 819 /* relock p's object: page queues not lock yet, so 820 * no need for "try" */ 821 822 /* !swap_backed case: already locked... */ 823 if (swap_backed) { 824 rw_enter(slock, RW_WRITE); 825 } 826 827 #ifdef DIAGNOSTIC 828 if (result == VM_PAGER_UNLOCK) 829 panic("pagedaemon: pageout returned " 830 "invalid 'unlock' code"); 831 #endif 832 833 /* handle PG_WANTED now */ 834 if (p->pg_flags & PG_WANTED) 835 wakeup(p); 836 837 atomic_clearbits_int(&p->pg_flags, PG_BUSY|PG_WANTED); 838 UVM_PAGE_OWN(p, NULL); 839 840 /* released during I/O? Can only happen for anons */ 841 if (p->pg_flags & PG_RELEASED) { 842 KASSERT(anon != NULL); 843 /* 844 * remove page so we can get nextpg, 845 * also zero out anon so we don't use 846 * it after the free. 847 */ 848 anon->an_page = NULL; 849 p->uanon = NULL; 850 851 uvm_anfree(anon); /* kills anon */ 852 pmap_page_protect(p, PROT_NONE); 853 anon = NULL; 854 uvm_lock_pageq(); 855 nextpg = TAILQ_NEXT(p, pageq); 856 /* free released page */ 857 uvm_pagefree(p); 858 } else { /* page was not released during I/O */ 859 uvm_lock_pageq(); 860 nextpg = TAILQ_NEXT(p, pageq); 861 if (result != VM_PAGER_OK) { 862 /* pageout was a failure... */ 863 if (result != VM_PAGER_AGAIN) 864 uvm_pageactivate(p); 865 pmap_clear_reference(p); 866 } else { 867 /* pageout was a success... */ 868 pmap_clear_reference(p); 869 pmap_clear_modify(p); 870 atomic_setbits_int(&p->pg_flags, 871 PG_CLEAN); 872 } 873 } 874 875 /* 876 * drop object lock (if there is an object left). do 877 * a safety check of nextpg to make sure it is on the 878 * inactive queue (it should be since PG_BUSY pages on 879 * the inactive queue can't be re-queued [note: not 880 * true for active queue]). 881 */ 882 rw_exit(slock); 883 884 if (nextpg && (nextpg->pg_flags & PQ_INACTIVE) == 0) { 885 nextpg = TAILQ_FIRST(pglst); /* reload! */ 886 } 887 } else { 888 /* 889 * if p is null in this loop, make sure it stays null 890 * in the next loop. 891 */ 892 nextpg = NULL; 893 894 /* 895 * lock page queues here just so they're always locked 896 * at the end of the loop. 897 */ 898 uvm_lock_pageq(); 899 } 900 } 901 902 return freed; 903 } 904 905 /* 906 * uvmpd_scan: scan the page queues and attempt to meet our targets. 907 * 908 * => called with pageq's locked 909 */ 910 911 void 912 uvmpd_scan(struct uvm_pmalloc *pma, int shortage, int inactive_shortage) 913 { 914 int swap_shortage, pages_freed; 915 916 MUTEX_ASSERT_LOCKED(&uvm.pageqlock); 917 918 uvmexp.pdrevs++; /* counter */ 919 920 921 #ifdef __HAVE_PMAP_COLLECT 922 /* 923 * swap out some processes if we are below our free target. 924 * we need to unlock the page queues for this. 925 */ 926 if (shortage > 0) { 927 uvmexp.pdswout++; 928 uvm_unlock_pageq(); 929 shortage -= uvm_swapout_threads(); 930 uvm_lock_pageq(); 931 } 932 #endif 933 934 /* 935 * now we want to work on meeting our targets. first we work on our 936 * free target by converting inactive pages into free pages. then 937 * we work on meeting our inactive target by converting active pages 938 * to inactive ones. 939 */ 940 pages_freed = uvmpd_scan_inactive(pma, shortage); 941 uvmexp.pdfreed += pages_freed; 942 shortage -= pages_freed; 943 944 /* 945 * we have done the scan to get free pages. now we work on meeting 946 * our inactive target. 947 * 948 * detect if we're not going to be able to page anything out 949 * until we free some swap resources from active pages. 950 */ 951 swap_shortage = 0; 952 if ((shortage > 0) && uvm_swapisfilled() && !uvm_swapisfull() && 953 pages_freed == 0) { 954 swap_shortage = shortage; 955 } 956 957 uvmpd_scan_active(pma, swap_shortage, inactive_shortage); 958 } 959 960 void 961 uvmpd_scan_active(struct uvm_pmalloc *pma, int swap_shortage, 962 int inactive_shortage) 963 { 964 struct vm_page *p, *nextpg; 965 struct rwlock *slock; 966 967 MUTEX_ASSERT_LOCKED(&uvm.pageqlock); 968 969 for (p = TAILQ_FIRST(&uvm.page_active); 970 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 971 p = nextpg) { 972 nextpg = TAILQ_NEXT(p, pageq); 973 if (p->pg_flags & PG_BUSY) { 974 continue; 975 } 976 977 /* 978 * If we couldn't release enough pages from a given memory 979 * range try to deactivate them first... 980 * 981 * ...unless we are low on swap slots, in such case we are 982 * probably OOM and want to release swap resources as quickly 983 * as possible. 984 */ 985 if (inactive_shortage > 0 && swap_shortage == 0 && 986 !uvmpd_pma_done(pma) && 987 !uvmpd_match_constraint(p, &pma->pm_constraint)) 988 continue; 989 990 /* 991 * lock the page's owner. 992 */ 993 slock = uvmpd_trylockowner(p); 994 if (slock == NULL) { 995 continue; 996 } 997 998 /* 999 * skip this page if it's busy. 1000 */ 1001 if ((p->pg_flags & PG_BUSY) != 0) { 1002 rw_exit(slock); 1003 continue; 1004 } 1005 1006 /* 1007 * if there's a shortage of swap, free any swap allocated 1008 * to this page so that other pages can be paged out. 1009 */ 1010 if (swap_shortage > 0) { 1011 if (uvmpd_dropswap(p)) { 1012 atomic_clearbits_int(&p->pg_flags, PG_CLEAN); 1013 swap_shortage--; 1014 } 1015 } 1016 1017 /* 1018 * deactivate this page if there's a shortage of 1019 * inactive pages. 1020 */ 1021 if (inactive_shortage > 0) { 1022 /* no need to check wire_count as pg is "active" */ 1023 uvm_pagedeactivate(p); 1024 uvmexp.pddeact++; 1025 inactive_shortage--; 1026 } 1027 1028 /* 1029 * we're done with this page. 1030 */ 1031 rw_exit(slock); 1032 } 1033 } 1034 1035 #ifdef HIBERNATE 1036 1037 /* 1038 * uvmpd_drop: drop clean pages from list 1039 */ 1040 void 1041 uvmpd_drop(struct pglist *pglst) 1042 { 1043 struct vm_page *p, *nextpg; 1044 1045 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 1046 nextpg = TAILQ_NEXT(p, pageq); 1047 1048 if (p->pg_flags & PQ_ANON || p->uobject == NULL) 1049 continue; 1050 1051 if (p->pg_flags & PG_BUSY) 1052 continue; 1053 1054 if (p->pg_flags & PG_CLEAN) { 1055 struct uvm_object * uobj = p->uobject; 1056 1057 rw_enter(uobj->vmobjlock, RW_WRITE); 1058 uvm_lock_pageq(); 1059 /* 1060 * we now have the page queues locked. 1061 * the page is not busy. if the page is clean we 1062 * can free it now and continue. 1063 */ 1064 if (p->pg_flags & PG_CLEAN) { 1065 if (p->pg_flags & PQ_SWAPBACKED) { 1066 /* this page now lives only in swap */ 1067 atomic_inc_int(&uvmexp.swpgonly); 1068 } 1069 1070 /* zap all mappings with pmap_page_protect... */ 1071 pmap_page_protect(p, PROT_NONE); 1072 uvm_pagefree(p); 1073 } 1074 uvm_unlock_pageq(); 1075 rw_exit(uobj->vmobjlock); 1076 } 1077 } 1078 } 1079 1080 void 1081 uvmpd_hibernate(void) 1082 { 1083 uvmpd_drop(&uvm.page_inactive); 1084 uvmpd_drop(&uvm.page_active); 1085 } 1086 1087 #endif 1088