1 /* $OpenBSD: uvm_pdaemon.c,v 1.89 2021/03/01 09:13:33 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 #if defined(__amd64__) || defined(__arm64__) || \ 85 defined(__i386__) || defined(__loongson__) || \ 86 defined(__macppc__) || defined(__sparc64__) 87 #include "drm.h" 88 #endif 89 90 #if NDRM > 0 91 extern void drmbackoff(long); 92 #endif 93 94 /* 95 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 96 * in a pass thru the inactive list when swap is full. the value should be 97 * "small"... if it's too large we'll cycle the active pages thru the inactive 98 * queue too quickly to for them to be referenced and avoid being freed. 99 */ 100 101 #define UVMPD_NUMDIRTYREACTS 16 102 103 104 /* 105 * local prototypes 106 */ 107 108 void uvmpd_scan(void); 109 boolean_t uvmpd_scan_inactive(struct pglist *); 110 void uvmpd_tune(void); 111 void uvmpd_drop(struct pglist *); 112 113 /* 114 * uvm_wait: wait (sleep) for the page daemon to free some pages 115 * 116 * => should be called with all locks released 117 * => should _not_ be called by the page daemon (to avoid deadlock) 118 */ 119 120 void 121 uvm_wait(const char *wmsg) 122 { 123 uint64_t timo = INFSLP; 124 125 #ifdef DIAGNOSTIC 126 if (curproc == &proc0) 127 panic("%s: cannot sleep for memory during boot", __func__); 128 #endif 129 130 /* check for page daemon going to sleep (waiting for itself) */ 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 /* now lock page queues and recompute inactive count */ 251 uvm_lock_pageq(); 252 if (npages != uvmexp.npages) { /* check for new pages? */ 253 npages = uvmexp.npages; 254 uvmpd_tune(); 255 } 256 257 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 258 if (uvmexp.inactarg <= uvmexp.freetarg) { 259 uvmexp.inactarg = uvmexp.freetarg + 1; 260 } 261 262 /* Reclaim pages from the buffer cache if possible. */ 263 size = 0; 264 if (pma != NULL) 265 size += pma->pm_size >> PAGE_SHIFT; 266 if (uvmexp.free - BUFPAGES_DEFICIT < uvmexp.freetarg) 267 size += uvmexp.freetarg - (uvmexp.free - 268 BUFPAGES_DEFICIT); 269 if (size == 0) 270 size = 16; /* XXX */ 271 uvm_unlock_pageq(); 272 (void) bufbackoff(&constraint, size * 2); 273 #if NDRM > 0 274 drmbackoff(size * 2); 275 #endif 276 uvm_lock_pageq(); 277 278 /* Scan if needed to meet our targets. */ 279 if (pma != NULL || 280 ((uvmexp.free - BUFPAGES_DEFICIT) < uvmexp.freetarg) || 281 ((uvmexp.inactive + BUFPAGES_INACT) < uvmexp.inactarg)) { 282 uvmpd_scan(); 283 } 284 285 /* 286 * if there's any free memory to be had, 287 * wake up any waiters. 288 */ 289 uvm_lock_fpageq(); 290 if (uvmexp.free > uvmexp.reserve_kernel || 291 uvmexp.paging == 0) { 292 wakeup(&uvmexp.free); 293 } 294 295 if (pma != NULL) { 296 /* 297 * XXX If UVM_PMA_FREED isn't set, no pages 298 * were freed. Should we set UVM_PMA_FAIL in 299 * that case? 300 */ 301 pma->pm_flags &= ~UVM_PMA_BUSY; 302 if (pma->pm_flags & UVM_PMA_FREED) { 303 pma->pm_flags &= ~UVM_PMA_LINKED; 304 TAILQ_REMOVE(&uvm.pmr_control.allocs, pma, 305 pmq); 306 wakeup(pma); 307 } 308 } 309 uvm_unlock_fpageq(); 310 311 /* scan done. unlock page queues (only lock we are holding) */ 312 uvm_unlock_pageq(); 313 314 sched_pause(yield); 315 } 316 /*NOTREACHED*/ 317 } 318 319 320 /* 321 * uvm_aiodone_daemon: main loop for the aiodone daemon. 322 */ 323 void 324 uvm_aiodone_daemon(void *arg) 325 { 326 int s, free; 327 struct buf *bp, *nbp; 328 329 uvm.aiodoned_proc = curproc; 330 331 for (;;) { 332 /* 333 * Check for done aio structures. If we've got structures to 334 * process, do so. Otherwise sleep while avoiding races. 335 */ 336 mtx_enter(&uvm.aiodoned_lock); 337 while ((bp = TAILQ_FIRST(&uvm.aio_done)) == NULL) 338 msleep_nsec(&uvm.aiodoned, &uvm.aiodoned_lock, 339 PVM, "aiodoned", INFSLP); 340 /* Take the list for ourselves. */ 341 TAILQ_INIT(&uvm.aio_done); 342 mtx_leave(&uvm.aiodoned_lock); 343 344 /* process each i/o that's done. */ 345 free = uvmexp.free; 346 while (bp != NULL) { 347 if (bp->b_flags & B_PDAEMON) { 348 uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT; 349 } 350 nbp = TAILQ_NEXT(bp, b_freelist); 351 s = splbio(); /* b_iodone must by called at splbio */ 352 (*bp->b_iodone)(bp); 353 splx(s); 354 bp = nbp; 355 356 sched_pause(yield); 357 } 358 uvm_lock_fpageq(); 359 wakeup(free <= uvmexp.reserve_kernel ? &uvm.pagedaemon : 360 &uvmexp.free); 361 uvm_unlock_fpageq(); 362 } 363 } 364 365 366 367 /* 368 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 369 * 370 * => called with page queues locked 371 * => we work on meeting our free target by converting inactive pages 372 * into free pages. 373 * => we handle the building of swap-backed clusters 374 * => we return TRUE if we are exiting because we met our target 375 */ 376 377 boolean_t 378 uvmpd_scan_inactive(struct pglist *pglst) 379 { 380 boolean_t retval = FALSE; /* assume we haven't hit target */ 381 int free, result; 382 struct vm_page *p, *nextpg; 383 struct uvm_object *uobj; 384 struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; 385 int npages; 386 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; /* XXX: see below */ 387 int swnpages, swcpages; /* XXX: see below */ 388 int swslot; 389 struct vm_anon *anon; 390 boolean_t swap_backed; 391 vaddr_t start; 392 int dirtyreacts; 393 394 /* 395 * note: we currently keep swap-backed pages on a separate inactive 396 * list from object-backed pages. however, merging the two lists 397 * back together again hasn't been ruled out. thus, we keep our 398 * swap cluster in "swpps" rather than in pps (allows us to mix 399 * clustering types in the event of a mixed inactive queue). 400 */ 401 /* 402 * swslot is non-zero if we are building a swap cluster. we want 403 * to stay in the loop while we have a page to scan or we have 404 * a swap-cluster to build. 405 */ 406 swslot = 0; 407 swnpages = swcpages = 0; 408 free = 0; 409 dirtyreacts = 0; 410 411 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 412 /* 413 * note that p can be NULL iff we have traversed the whole 414 * list and need to do one final swap-backed clustered pageout. 415 */ 416 uobj = NULL; 417 anon = NULL; 418 419 if (p) { 420 /* 421 * update our copy of "free" and see if we've met 422 * our target 423 */ 424 free = uvmexp.free - BUFPAGES_DEFICIT; 425 426 if (free + uvmexp.paging >= uvmexp.freetarg << 2 || 427 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 428 retval = TRUE; 429 430 if (swslot == 0) { 431 /* exit now if no swap-i/o pending */ 432 break; 433 } 434 435 /* set p to null to signal final swap i/o */ 436 p = NULL; 437 } 438 } 439 440 if (p) { /* if (we have a new page to consider) */ 441 /* 442 * we are below target and have a new page to consider. 443 */ 444 uvmexp.pdscans++; 445 nextpg = TAILQ_NEXT(p, pageq); 446 447 /* 448 * move referenced pages back to active queue and 449 * skip to next page (unlikely to happen since 450 * inactive pages shouldn't have any valid mappings 451 * and we cleared reference before deactivating). 452 */ 453 454 if (pmap_is_referenced(p)) { 455 uvm_pageactivate(p); 456 uvmexp.pdreact++; 457 continue; 458 } 459 460 if (p->pg_flags & PQ_ANON) { 461 anon = p->uanon; 462 KASSERT(anon != NULL); 463 if (rw_enter(anon->an_lock, 464 RW_WRITE|RW_NOSLEEP)) { 465 /* lock failed, skip this page */ 466 continue; 467 } 468 if (p->pg_flags & PG_BUSY) { 469 rw_exit(anon->an_lock); 470 uvmexp.pdbusy++; 471 /* someone else owns page, skip it */ 472 continue; 473 } 474 uvmexp.pdanscan++; 475 } else { 476 uobj = p->uobject; 477 KASSERT(uobj != NULL); 478 if (p->pg_flags & PG_BUSY) { 479 uvmexp.pdbusy++; 480 /* someone else owns page, skip it */ 481 continue; 482 } 483 uvmexp.pdobscan++; 484 } 485 486 /* 487 * we now have the page queues locked. 488 * the page is not busy. if the page is clean we 489 * can free it now and continue. 490 */ 491 if (p->pg_flags & PG_CLEAN) { 492 if (p->pg_flags & PQ_SWAPBACKED) { 493 /* this page now lives only in swap */ 494 uvmexp.swpgonly++; 495 } 496 497 /* zap all mappings with pmap_page_protect... */ 498 pmap_page_protect(p, PROT_NONE); 499 uvm_pagefree(p); 500 uvmexp.pdfreed++; 501 502 if (anon) { 503 504 /* 505 * an anonymous page can only be clean 506 * if it has backing store assigned. 507 */ 508 509 KASSERT(anon->an_swslot != 0); 510 511 /* remove from object */ 512 anon->an_page = NULL; 513 rw_exit(anon->an_lock); 514 } 515 continue; 516 } 517 518 /* 519 * this page is dirty, skip it if we'll have met our 520 * free target when all the current pageouts complete. 521 */ 522 if (free + uvmexp.paging > uvmexp.freetarg << 2) { 523 if (anon) { 524 rw_exit(anon->an_lock); 525 } 526 continue; 527 } 528 529 /* 530 * this page is dirty, but we can't page it out 531 * since all pages in swap are only in swap. 532 * reactivate it so that we eventually cycle 533 * all pages thru the inactive queue. 534 */ 535 if ((p->pg_flags & PQ_SWAPBACKED) && uvm_swapisfull()) { 536 dirtyreacts++; 537 uvm_pageactivate(p); 538 if (anon) { 539 rw_exit(anon->an_lock); 540 } 541 continue; 542 } 543 544 /* 545 * if the page is swap-backed and dirty and swap space 546 * is full, free any swap allocated to the page 547 * so that other pages can be paged out. 548 */ 549 KASSERT(uvmexp.swpginuse <= uvmexp.swpages); 550 if ((p->pg_flags & PQ_SWAPBACKED) && 551 uvmexp.swpginuse == uvmexp.swpages) { 552 553 if ((p->pg_flags & PQ_ANON) && 554 p->uanon->an_swslot) { 555 uvm_swap_free(p->uanon->an_swslot, 1); 556 p->uanon->an_swslot = 0; 557 } 558 if (p->pg_flags & PQ_AOBJ) { 559 uao_dropswap(p->uobject, 560 p->offset >> PAGE_SHIFT); 561 } 562 } 563 564 /* 565 * the page we are looking at is dirty. we must 566 * clean it before it can be freed. to do this we 567 * first mark the page busy so that no one else will 568 * touch the page. we write protect all the mappings 569 * of the page so that no one touches it while it is 570 * in I/O. 571 */ 572 573 swap_backed = ((p->pg_flags & PQ_SWAPBACKED) != 0); 574 atomic_setbits_int(&p->pg_flags, PG_BUSY); 575 UVM_PAGE_OWN(p, "scan_inactive"); 576 pmap_page_protect(p, PROT_READ); 577 uvmexp.pgswapout++; 578 579 /* 580 * for swap-backed pages we need to (re)allocate 581 * swap space. 582 */ 583 if (swap_backed) { 584 /* free old swap slot (if any) */ 585 if (anon) { 586 if (anon->an_swslot) { 587 uvm_swap_free(anon->an_swslot, 588 1); 589 anon->an_swslot = 0; 590 } 591 } else { 592 uao_dropswap(uobj, 593 p->offset >> PAGE_SHIFT); 594 } 595 596 /* start new cluster (if necessary) */ 597 if (swslot == 0) { 598 swnpages = MAXBSIZE >> PAGE_SHIFT; 599 swslot = uvm_swap_alloc(&swnpages, 600 TRUE); 601 if (swslot == 0) { 602 /* no swap? give up! */ 603 atomic_clearbits_int( 604 &p->pg_flags, 605 PG_BUSY); 606 UVM_PAGE_OWN(p, NULL); 607 if (anon) 608 rw_exit(anon->an_lock); 609 continue; 610 } 611 swcpages = 0; /* cluster is empty */ 612 } 613 614 /* add block to cluster */ 615 swpps[swcpages] = p; 616 if (anon) 617 anon->an_swslot = swslot + swcpages; 618 else 619 uao_set_swslot(uobj, 620 p->offset >> PAGE_SHIFT, 621 swslot + swcpages); 622 swcpages++; 623 } 624 } else { 625 /* if p == NULL we must be doing a last swap i/o */ 626 swap_backed = TRUE; 627 } 628 629 /* 630 * now consider doing the pageout. 631 * 632 * for swap-backed pages, we do the pageout if we have either 633 * filled the cluster (in which case (swnpages == swcpages) or 634 * run out of pages (p == NULL). 635 * 636 * for object pages, we always do the pageout. 637 */ 638 if (swap_backed) { 639 if (p) { /* if we just added a page to cluster */ 640 if (anon) 641 rw_exit(anon->an_lock); 642 643 /* cluster not full yet? */ 644 if (swcpages < swnpages) 645 continue; 646 } 647 648 /* starting I/O now... set up for it */ 649 npages = swcpages; 650 ppsp = swpps; 651 /* for swap-backed pages only */ 652 start = (vaddr_t) swslot; 653 654 /* if this is final pageout we could have a few 655 * extra swap blocks */ 656 if (swcpages < swnpages) { 657 uvm_swap_free(swslot + swcpages, 658 (swnpages - swcpages)); 659 } 660 } else { 661 /* normal object pageout */ 662 ppsp = pps; 663 npages = sizeof(pps) / sizeof(struct vm_page *); 664 /* not looked at because PGO_ALLPAGES is set */ 665 start = 0; 666 } 667 668 /* 669 * now do the pageout. 670 * 671 * for swap_backed pages we have already built the cluster. 672 * for !swap_backed pages, uvm_pager_put will call the object's 673 * "make put cluster" function to build a cluster on our behalf. 674 * 675 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 676 * it to free the cluster pages for us on a successful I/O (it 677 * always does this for un-successful I/O requests). this 678 * allows us to do clustered pageout without having to deal 679 * with cluster pages at this level. 680 * 681 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 682 * IN: locked: page queues 683 * OUT: locked: 684 * !locked: pageqs 685 */ 686 687 uvmexp.pdpageouts++; 688 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 689 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 690 691 /* 692 * if we did i/o to swap, zero swslot to indicate that we are 693 * no longer building a swap-backed cluster. 694 */ 695 696 if (swap_backed) 697 swslot = 0; /* done with this cluster */ 698 699 /* 700 * first, we check for VM_PAGER_PEND which means that the 701 * async I/O is in progress and the async I/O done routine 702 * will clean up after us. in this case we move on to the 703 * next page. 704 * 705 * there is a very remote chance that the pending async i/o can 706 * finish _before_ we get here. if that happens, our page "p" 707 * may no longer be on the inactive queue. so we verify this 708 * when determining the next page (starting over at the head if 709 * we've lost our inactive page). 710 */ 711 712 if (result == VM_PAGER_PEND) { 713 uvmexp.paging += npages; 714 uvm_lock_pageq(); 715 uvmexp.pdpending++; 716 if (p) { 717 if (p->pg_flags & PQ_INACTIVE) 718 nextpg = TAILQ_NEXT(p, pageq); 719 else 720 nextpg = TAILQ_FIRST(pglst); 721 } else { 722 nextpg = NULL; 723 } 724 continue; 725 } 726 727 /* clean up "p" if we have one */ 728 if (p) { 729 /* 730 * the I/O request to "p" is done and uvm_pager_put 731 * has freed any cluster pages it may have allocated 732 * during I/O. all that is left for us to do is 733 * clean up page "p" (which is still PG_BUSY). 734 * 735 * our result could be one of the following: 736 * VM_PAGER_OK: successful pageout 737 * 738 * VM_PAGER_AGAIN: tmp resource shortage, we skip 739 * to next page 740 * VM_PAGER_{FAIL,ERROR,BAD}: an error. we 741 * "reactivate" page to get it out of the way (it 742 * will eventually drift back into the inactive 743 * queue for a retry). 744 * VM_PAGER_UNLOCK: should never see this as it is 745 * only valid for "get" operations 746 */ 747 748 /* relock p's object: page queues not lock yet, so 749 * no need for "try" */ 750 751 /* !swap_backed case: already locked... */ 752 if (swap_backed) { 753 if (anon) 754 rw_enter(anon->an_lock, RW_WRITE); 755 } 756 757 #ifdef DIAGNOSTIC 758 if (result == VM_PAGER_UNLOCK) 759 panic("pagedaemon: pageout returned " 760 "invalid 'unlock' code"); 761 #endif 762 763 /* handle PG_WANTED now */ 764 if (p->pg_flags & PG_WANTED) 765 wakeup(p); 766 767 atomic_clearbits_int(&p->pg_flags, PG_BUSY|PG_WANTED); 768 UVM_PAGE_OWN(p, NULL); 769 770 /* released during I/O? Can only happen for anons */ 771 if (p->pg_flags & PG_RELEASED) { 772 KASSERT(anon != NULL); 773 /* 774 * remove page so we can get nextpg, 775 * also zero out anon so we don't use 776 * it after the free. 777 */ 778 anon->an_page = NULL; 779 p->uanon = NULL; 780 781 rw_exit(anon->an_lock); 782 uvm_anfree(anon); /* kills anon */ 783 pmap_page_protect(p, PROT_NONE); 784 anon = NULL; 785 uvm_lock_pageq(); 786 nextpg = TAILQ_NEXT(p, pageq); 787 /* free released page */ 788 uvm_pagefree(p); 789 } else { /* page was not released during I/O */ 790 uvm_lock_pageq(); 791 nextpg = TAILQ_NEXT(p, pageq); 792 if (result != VM_PAGER_OK) { 793 /* pageout was a failure... */ 794 if (result != VM_PAGER_AGAIN) 795 uvm_pageactivate(p); 796 pmap_clear_reference(p); 797 /* XXXCDC: if (swap_backed) FREE p's 798 * swap block? */ 799 } else { 800 /* pageout was a success... */ 801 pmap_clear_reference(p); 802 pmap_clear_modify(p); 803 atomic_setbits_int(&p->pg_flags, 804 PG_CLEAN); 805 } 806 } 807 808 /* 809 * drop object lock (if there is an object left). do 810 * a safety check of nextpg to make sure it is on the 811 * inactive queue (it should be since PG_BUSY pages on 812 * the inactive queue can't be re-queued [note: not 813 * true for active queue]). 814 */ 815 if (anon) 816 rw_exit(anon->an_lock); 817 818 if (nextpg && (nextpg->pg_flags & PQ_INACTIVE) == 0) { 819 nextpg = TAILQ_FIRST(pglst); /* reload! */ 820 } 821 } else { 822 /* 823 * if p is null in this loop, make sure it stays null 824 * in the next loop. 825 */ 826 nextpg = NULL; 827 828 /* 829 * lock page queues here just so they're always locked 830 * at the end of the loop. 831 */ 832 uvm_lock_pageq(); 833 } 834 } 835 return (retval); 836 } 837 838 /* 839 * uvmpd_scan: scan the page queues and attempt to meet our targets. 840 * 841 * => called with pageq's locked 842 */ 843 844 void 845 uvmpd_scan(void) 846 { 847 int free, inactive_shortage, swap_shortage, pages_freed; 848 struct vm_page *p, *nextpg; 849 struct uvm_object *uobj; 850 boolean_t got_it; 851 852 MUTEX_ASSERT_LOCKED(&uvm.pageqlock); 853 854 uvmexp.pdrevs++; /* counter */ 855 uobj = NULL; 856 857 /* 858 * get current "free" page count 859 */ 860 free = uvmexp.free - BUFPAGES_DEFICIT; 861 862 #ifndef __SWAP_BROKEN 863 /* 864 * swap out some processes if we are below our free target. 865 * we need to unlock the page queues for this. 866 */ 867 if (free < uvmexp.freetarg) { 868 uvmexp.pdswout++; 869 uvm_unlock_pageq(); 870 uvm_swapout_threads(); 871 uvm_lock_pageq(); 872 } 873 #endif 874 875 /* 876 * now we want to work on meeting our targets. first we work on our 877 * free target by converting inactive pages into free pages. then 878 * we work on meeting our inactive target by converting active pages 879 * to inactive ones. 880 */ 881 882 /* 883 * alternate starting queue between swap and object based on the 884 * low bit of uvmexp.pdrevs (which we bump by one each call). 885 */ 886 got_it = FALSE; 887 pages_freed = uvmexp.pdfreed; /* XXX - int */ 888 if ((uvmexp.pdrevs & 1) != 0 && uvmexp.nswapdev != 0) 889 got_it = uvmpd_scan_inactive(&uvm.page_inactive_swp); 890 if (!got_it) 891 got_it = uvmpd_scan_inactive(&uvm.page_inactive_obj); 892 if (!got_it && (uvmexp.pdrevs & 1) == 0 && uvmexp.nswapdev != 0) 893 (void) uvmpd_scan_inactive(&uvm.page_inactive_swp); 894 pages_freed = uvmexp.pdfreed - pages_freed; 895 896 /* 897 * we have done the scan to get free pages. now we work on meeting 898 * our inactive target. 899 */ 900 inactive_shortage = uvmexp.inactarg - uvmexp.inactive - BUFPAGES_INACT; 901 902 /* 903 * detect if we're not going to be able to page anything out 904 * until we free some swap resources from active pages. 905 */ 906 swap_shortage = 0; 907 if (uvmexp.free < uvmexp.freetarg && 908 uvmexp.swpginuse == uvmexp.swpages && 909 !uvm_swapisfull() && 910 pages_freed == 0) { 911 swap_shortage = uvmexp.freetarg - uvmexp.free; 912 } 913 914 for (p = TAILQ_FIRST(&uvm.page_active); 915 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 916 p = nextpg) { 917 nextpg = TAILQ_NEXT(p, pageq); 918 919 /* skip this page if it's busy. */ 920 if (p->pg_flags & PG_BUSY) 921 continue; 922 923 if (p->pg_flags & PQ_ANON) { 924 KASSERT(p->uanon != NULL); 925 if (rw_enter(p->uanon->an_lock, RW_WRITE|RW_NOSLEEP)) 926 continue; 927 } else 928 KASSERT(p->uobject != NULL); 929 930 /* 931 * if there's a shortage of swap, free any swap allocated 932 * to this page so that other pages can be paged out. 933 */ 934 if (swap_shortage > 0) { 935 if ((p->pg_flags & PQ_ANON) && p->uanon->an_swslot) { 936 uvm_swap_free(p->uanon->an_swslot, 1); 937 p->uanon->an_swslot = 0; 938 atomic_clearbits_int(&p->pg_flags, PG_CLEAN); 939 swap_shortage--; 940 } 941 if (p->pg_flags & PQ_AOBJ) { 942 int slot = uao_set_swslot(p->uobject, 943 p->offset >> PAGE_SHIFT, 0); 944 if (slot) { 945 uvm_swap_free(slot, 1); 946 atomic_clearbits_int(&p->pg_flags, 947 PG_CLEAN); 948 swap_shortage--; 949 } 950 } 951 } 952 953 /* 954 * deactivate this page if there's a shortage of 955 * inactive pages. 956 */ 957 if (inactive_shortage > 0) { 958 pmap_page_protect(p, PROT_NONE); 959 /* no need to check wire_count as pg is "active" */ 960 uvm_pagedeactivate(p); 961 uvmexp.pddeact++; 962 inactive_shortage--; 963 } 964 if (p->pg_flags & PQ_ANON) 965 rw_exit(p->uanon->an_lock); 966 } 967 } 968 969 #ifdef HIBERNATE 970 971 /* 972 * uvmpd_drop: drop clean pages from list 973 */ 974 void 975 uvmpd_drop(struct pglist *pglst) 976 { 977 struct vm_page *p, *nextpg; 978 979 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 980 nextpg = TAILQ_NEXT(p, pageq); 981 982 if (p->pg_flags & PQ_ANON || p->uobject == NULL) 983 continue; 984 985 if (p->pg_flags & PG_BUSY) 986 continue; 987 988 if (p->pg_flags & PG_CLEAN) { 989 /* 990 * we now have the page queues locked. 991 * the page is not busy. if the page is clean we 992 * can free it now and continue. 993 */ 994 if (p->pg_flags & PG_CLEAN) { 995 if (p->pg_flags & PQ_SWAPBACKED) { 996 /* this page now lives only in swap */ 997 uvmexp.swpgonly++; 998 } 999 1000 /* zap all mappings with pmap_page_protect... */ 1001 pmap_page_protect(p, PROT_NONE); 1002 uvm_pagefree(p); 1003 } 1004 } 1005 } 1006 } 1007 1008 void 1009 uvmpd_hibernate(void) 1010 { 1011 uvm_lock_pageq(); 1012 1013 uvmpd_drop(&uvm.page_inactive_swp); 1014 uvmpd_drop(&uvm.page_inactive_obj); 1015 uvmpd_drop(&uvm.page_active); 1016 1017 uvm_unlock_pageq(); 1018 } 1019 1020 #endif 1021