sys/vm/vm_pageout.c

   1 /*-
   2  * Copyright (c) 1991 Regents of the University of California.
   3  * All rights reserved.
   4  * Copyright (c) 1994 John S. Dyson
   5  * All rights reserved.
   6  * Copyright (c) 1994 David Greenman
   7  * All rights reserved.
   8  * Copyright (c) 2005 Yahoo! Technologies Norway AS
   9  * All rights reserved.
  10  *
  11  * This code is derived from software contributed to Berkeley by
  12  * The Mach Operating System project at Carnegie-Mellon University.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. All advertising materials mentioning features or use of this software
  23  *    must display the following acknowledgement:
  24  *      This product includes software developed by the University of
  25  *      California, Berkeley and its contributors.
  26  * 4. Neither the name of the University nor the names of its contributors
  27  *    may be used to endorse or promote products derived from this software
  28  *    without specific prior written permission.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  40  * SUCH DAMAGE.
  41  *
  42  *      from: @(#)vm_pageout.c  7.4 (Berkeley) 5/7/91
  43  *
  44  *
  45  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
  46  * All rights reserved.
  47  *
  48  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
  49  *
  50  * Permission to use, copy, modify and distribute this software and
  51  * its documentation is hereby granted, provided that both the copyright
  52  * notice and this permission notice appear in all copies of the
  53  * software, derivative works or modified versions, and any portions
  54  * thereof, and that both notices appear in supporting documentation.
  55  *
  56  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  57  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
  58  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  59  *
  60  * Carnegie Mellon requests users of this software to return to
  61  *
  62  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  63  *  School of Computer Science
  64  *  Carnegie Mellon University
  65  *  Pittsburgh PA 15213-3890
  66  *
  67  * any improvements or extensions that they make and grant Carnegie the
  68  * rights to redistribute these changes.
  69  */
  70
  71 /*
  72  *      The proverbial page-out daemon.
  73  */
  74
  75 #include <sys/cdefs.h>
  76 __FBSDID("$FreeBSD$");
  77
  78 #include "opt_vm.h"
  79 #include "opt_kdtrace.h"
  80 #include <sys/param.h>
  81 #include <sys/systm.h>
  82 #include <sys/kernel.h>
  83 #include <sys/eventhandler.h>
  84 #include <sys/lock.h>
  85 #include <sys/mutex.h>
  86 #include <sys/proc.h>
  87 #include <sys/kthread.h>
  88 #include <sys/ktr.h>
  89 #include <sys/mount.h>
  90 #include <sys/racct.h>
  91 #include <sys/resourcevar.h>
  92 #include <sys/sched.h>
  93 #include <sys/sdt.h>
  94 #include <sys/signalvar.h>
  95 #include <sys/smp.h>
  96 #include <sys/vnode.h>
  97 #include <sys/vmmeter.h>
  98 #include <sys/rwlock.h>
  99 #include <sys/sx.h>
 100 #include <sys/sysctl.h>
 101
 102 #include <vm/vm.h>
 103 #include <vm/vm_param.h>
 104 #include <vm/vm_object.h>
 105 #include <vm/vm_page.h>
 106 #include <vm/vm_map.h>
 107 #include <vm/vm_pageout.h>
 108 #include <vm/vm_pager.h>
 109 #include <vm/vm_phys.h>
 110 #include <vm/swap_pager.h>
 111 #include <vm/vm_extern.h>
 112 #include <vm/uma.h>
 113
 114 /*
 115  * System initialization
 116  */
 117
 118 /* the kernel process "vm_pageout"*/
 119 static void vm_pageout(void);
 120 static void vm_pageout_init(void);
 121 static int vm_pageout_clean(vm_page_t m);
 122 static int vm_pageout_cluster(vm_page_t m);
 123 static void vm_pageout_scan(struct vm_domain *vmd, int pass);
 124 static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass);
 125
 126 SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init,
 127     NULL);
 128
 129 struct proc *pageproc;
 130
 131 static struct kproc_desc page_kp = {
 132         "pagedaemon",
 133         vm_pageout,
 134         &pageproc
 135 };
 136 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start,
 137     &page_kp);
 138
 139 SDT_PROVIDER_DEFINE(vm);
 140 SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache);
 141 SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan);
 142
 143 #if !defined(NO_SWAPPING)
 144 /* the kernel process "vm_daemon"*/
 145 static void vm_daemon(void);
 146 static struct   proc *vmproc;
 147
 148 static struct kproc_desc vm_kp = {
 149         "vmdaemon",
 150         vm_daemon,
 151         &vmproc
 152 };
 153 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
 154 #endif
 155
 156
 157 int vm_pages_needed;            /* Event on which pageout daemon sleeps */
 158 int vm_pageout_deficit;         /* Estimated number of pages deficit */
 159 int vm_pageout_pages_needed;    /* flag saying that the pageout daemon needs pages */
 160 int vm_pageout_wakeup_thresh;
 161
 162 #if !defined(NO_SWAPPING)
 163 static int vm_pageout_req_swapout;      /* XXX */
 164 static int vm_daemon_needed;
 165 static struct mtx vm_daemon_mtx;
 166 /* Allow for use by vm_pageout before vm_daemon is initialized. */
 167 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
 168 #endif
 169 static int vm_max_launder = 32;
 170 static int vm_pageout_update_period;
 171 static int defer_swap_pageouts;
 172 static int disable_swap_pageouts;
 173 static int lowmem_period = 10;
 174 static int lowmem_ticks;
 175
 176 #if defined(NO_SWAPPING)
 177 static int vm_swap_enabled = 0;
 178 static int vm_swap_idle_enabled = 0;
 179 #else
 180 static int vm_swap_enabled = 1;
 181 static int vm_swap_idle_enabled = 0;
 182 #endif
 183
 184 static int vm_panic_on_oom = 0;
 185
 186 SYSCTL_INT(_vm, OID_AUTO, panic_on_oom,
 187         CTLFLAG_RWTUN, &vm_panic_on_oom, 0,
 188         "panic on out of memory instead of killing the largest process");
 189
 190 SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh,
 191         CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0,
 192         "free page threshold for waking up the pageout daemon");
 193
 194 SYSCTL_INT(_vm, OID_AUTO, max_launder,
 195         CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
 196
 197 SYSCTL_INT(_vm, OID_AUTO, pageout_update_period,
 198         CTLFLAG_RW, &vm_pageout_update_period, 0,
 199         "Maximum active LRU update period");
 200
 201 SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0,
 202         "Low memory callback period");
 203
 204 #if defined(NO_SWAPPING)
 205 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
 206         CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout");
 207 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
 208         CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
 209 #else
 210 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
 211         CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
 212 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
 213         CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
 214 #endif
 215
 216 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
 217         CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
 218
 219 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
 220         CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
 221
 222 static int pageout_lock_miss;
 223 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
 224         CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
 225
 226 #define VM_PAGEOUT_PAGE_COUNT 16
 227 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
 228
 229 int vm_page_max_wired;          /* XXX max # of wired pages system-wide */
 230 SYSCTL_INT(_vm, OID_AUTO, max_wired,
 231         CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
 232
 233 static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
 234 static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t,
 235     vm_paddr_t);
 236 #if !defined(NO_SWAPPING)
 237 static void vm_pageout_map_deactivate_pages(vm_map_t, long);
 238 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
 239 static void vm_req_vmdaemon(int req);
 240 #endif
 241 static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *);
 242
 243 /*
 244  * Initialize a dummy page for marking the caller's place in the specified
 245  * paging queue.  In principle, this function only needs to set the flag
 246  * PG_MARKER.  Nonetheless, it wirte busies and initializes the hold count
 247  * to one as safety precautions.
 248  */
 249 static void
 250 vm_pageout_init_marker(vm_page_t marker, u_short queue)
 251 {
 252
 253         bzero(marker, sizeof(*marker));
 254         marker->flags = PG_MARKER;
 255         marker->busy_lock = VPB_SINGLE_EXCLUSIVER;
 256         marker->queue = queue;
 257         marker->hold_count = 1;
 258 }
 259
 260 /*
 261  * vm_pageout_fallback_object_lock:
 262  *
 263  * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is
 264  * known to have failed and page queue must be either PQ_ACTIVE or
 265  * PQ_INACTIVE.  To avoid lock order violation, unlock the page queues
 266  * while locking the vm object.  Use marker page to detect page queue
 267  * changes and maintain notion of next page on page queue.  Return
 268  * TRUE if no changes were detected, FALSE otherwise.  vm object is
 269  * locked on return.
 270  *
 271  * This function depends on both the lock portion of struct vm_object
 272  * and normal struct vm_page being type stable.
 273  */
 274 static boolean_t
 275 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
 276 {
 277         struct vm_page marker;
 278         struct vm_pagequeue *pq;
 279         boolean_t unchanged;
 280         u_short queue;
 281         vm_object_t object;
 282
 283         queue = m->queue;
 284         vm_pageout_init_marker(&marker, queue);
 285         pq = vm_page_pagequeue(m);
 286         object = m->object;
 287
 288         TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
 289         vm_pagequeue_unlock(pq);
 290         vm_page_unlock(m);
 291         VM_OBJECT_WLOCK(object);
 292         vm_page_lock(m);
 293         vm_pagequeue_lock(pq);
 294
 295         /* Page queue might have changed. */
 296         *next = TAILQ_NEXT(&marker, plinks.q);
 297         unchanged = (m->queue == queue &&
 298                      m->object == object &&
 299                      &marker == TAILQ_NEXT(m, plinks.q));
 300         TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
 301         return (unchanged);
 302 }
 303
 304 /*
 305  * Lock the page while holding the page queue lock.  Use marker page
 306  * to detect page queue changes and maintain notion of next page on
 307  * page queue.  Return TRUE if no changes were detected, FALSE
 308  * otherwise.  The page is locked on return. The page queue lock might
 309  * be dropped and reacquired.
 310  *
 311  * This function depends on normal struct vm_page being type stable.
 312  */
 313 static boolean_t
 314 vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
 315 {
 316         struct vm_page marker;
 317         struct vm_pagequeue *pq;
 318         boolean_t unchanged;
 319         u_short queue;
 320
 321         vm_page_lock_assert(m, MA_NOTOWNED);
 322         if (vm_page_trylock(m))
 323                 return (TRUE);
 324
 325         queue = m->queue;
 326         vm_pageout_init_marker(&marker, queue);
 327         pq = vm_page_pagequeue(m);
 328
 329         TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
 330         vm_pagequeue_unlock(pq);
 331         vm_page_lock(m);
 332         vm_pagequeue_lock(pq);
 333
 334         /* Page queue might have changed. */
 335         *next = TAILQ_NEXT(&marker, plinks.q);
 336         unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q));
 337         TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
 338         return (unchanged);
 339 }
 340
 341 /*
 342  * vm_pageout_clean:
 343  *
 344  * Clean the page and remove it from the laundry.
 345  *
 346  * We set the busy bit to cause potential page faults on this page to
 347  * block.  Note the careful timing, however, the busy bit isn't set till
 348  * late and we cannot do anything that will mess with the page.
 349  */
 350 static int
 351 vm_pageout_cluster(vm_page_t m)
 352 {
 353         vm_object_t object;
 354         vm_page_t mc[2*vm_pageout_page_count], pb, ps;
 355         int pageout_count;
 356         int ib, is, page_base;
 357         vm_pindex_t pindex = m->pindex;
 358
 359         vm_page_lock_assert(m, MA_OWNED);
 360         object = m->object;
 361         VM_OBJECT_ASSERT_WLOCKED(object);
 362
 363         /*
 364          * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
 365          * with the new swapper, but we could have serious problems paging
 366          * out other object types if there is insufficient memory.
 367          *
 368          * Unfortunately, checking free memory here is far too late, so the
 369          * check has been moved up a procedural level.
 370          */
 371
 372         /*
 373          * Can't clean the page if it's busy or held.
 374          */
 375         vm_page_assert_unbusied(m);
 376         KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m));
 377         vm_page_unlock(m);
 378
 379         mc[vm_pageout_page_count] = pb = ps = m;
 380         pageout_count = 1;
 381         page_base = vm_pageout_page_count;
 382         ib = 1;
 383         is = 1;
 384
 385         /*
 386          * Scan object for clusterable pages.
 387          *
 388          * We can cluster ONLY if: ->> the page is NOT
 389          * clean, wired, busy, held, or mapped into a
 390          * buffer, and one of the following:
 391          * 1) The page is inactive, or a seldom used
 392          *    active page.
 393          * -or-
 394          * 2) we force the issue.
 395          *
 396          * During heavy mmap/modification loads the pageout
 397          * daemon can really fragment the underlying file
 398          * due to flushing pages out of order and not trying
 399          * align the clusters (which leave sporatic out-of-order
 400          * holes).  To solve this problem we do the reverse scan
 401          * first and attempt to align our cluster, then do a
 402          * forward scan if room remains.
 403          */
 404 more:
 405         while (ib && pageout_count < vm_pageout_page_count) {
 406                 vm_page_t p;
 407
 408                 if (ib > pindex) {
 409                         ib = 0;
 410                         break;
 411                 }
 412
 413                 if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) {
 414                         ib = 0;
 415                         break;
 416                 }
 417                 vm_page_lock(p);
 418                 vm_page_test_dirty(p);
 419                 if (p->dirty == 0 ||
 420                     p->queue != PQ_INACTIVE ||
 421                     p->hold_count != 0) {       /* may be undergoing I/O */
 422                         vm_page_unlock(p);
 423                         ib = 0;
 424                         break;
 425                 }
 426                 vm_page_unlock(p);
 427                 mc[--page_base] = pb = p;
 428                 ++pageout_count;
 429                 ++ib;
 430                 /*
 431                  * alignment boundry, stop here and switch directions.  Do
 432                  * not clear ib.
 433                  */
 434                 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
 435                         break;
 436         }
 437
 438         while (pageout_count < vm_pageout_page_count &&
 439             pindex + is < object->size) {
 440                 vm_page_t p;
 441
 442                 if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
 443                         break;
 444                 vm_page_lock(p);
 445                 vm_page_test_dirty(p);
 446                 if (p->dirty == 0 ||
 447                     p->queue != PQ_INACTIVE ||
 448                     p->hold_count != 0) {       /* may be undergoing I/O */
 449                         vm_page_unlock(p);
 450                         break;
 451                 }
 452                 vm_page_unlock(p);
 453                 mc[page_base + pageout_count] = ps = p;
 454                 ++pageout_count;
 455                 ++is;
 456         }
 457
 458         /*
 459          * If we exhausted our forward scan, continue with the reverse scan
 460          * when possible, even past a page boundry.  This catches boundry
 461          * conditions.
 462          */
 463         if (ib && pageout_count < vm_pageout_page_count)
 464                 goto more;
 465
 466         /*
 467          * we allow reads during pageouts...
 468          */
 469         return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL,
 470             NULL));
 471 }
 472
 473 /*
 474  * vm_pageout_flush() - launder the given pages
 475  *
 476  *      The given pages are laundered.  Note that we setup for the start of
 477  *      I/O ( i.e. busy the page ), mark it read-only, and bump the object
 478  *      reference count all in here rather then in the parent.  If we want
 479  *      the parent to do more sophisticated things we may have to change
 480  *      the ordering.
 481  *
 482  *      Returned runlen is the count of pages between mreq and first
 483  *      page after mreq with status VM_PAGER_AGAIN.
 484  *      *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL
 485  *      for any page in runlen set.
 486  */
 487 int
 488 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
 489     boolean_t *eio)
 490 {
 491         vm_object_t object = mc[0]->object;
 492         int pageout_status[count];
 493         int numpagedout = 0;
 494         int i, runlen;
 495
 496         VM_OBJECT_ASSERT_WLOCKED(object);
 497
 498         /*
 499          * Initiate I/O.  Bump the vm_page_t->busy counter and
 500          * mark the pages read-only.
 501          *
 502          * We do not have to fixup the clean/dirty bits here... we can
 503          * allow the pager to do it after the I/O completes.
 504          *
 505          * NOTE! mc[i]->dirty may be partial or fragmented due to an
 506          * edge case with file fragments.
 507          */
 508         for (i = 0; i < count; i++) {
 509                 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
 510                     ("vm_pageout_flush: partially invalid page %p index %d/%d",
 511                         mc[i], i, count));
 512                 vm_page_sbusy(mc[i]);
 513                 pmap_remove_write(mc[i]);
 514         }
 515         vm_object_pip_add(object, count);
 516
 517         vm_pager_put_pages(object, mc, count, flags, pageout_status);
 518
 519         runlen = count - mreq;
 520         if (eio != NULL)
 521                 *eio = FALSE;
 522         for (i = 0; i < count; i++) {
 523                 vm_page_t mt = mc[i];
 524
 525                 KASSERT(pageout_status[i] == VM_PAGER_PEND ||
 526                     !pmap_page_is_write_mapped(mt),
 527                     ("vm_pageout_flush: page %p is not write protected", mt));
 528                 switch (pageout_status[i]) {
 529                 case VM_PAGER_OK:
 530                 case VM_PAGER_PEND:
 531                         numpagedout++;
 532                         break;
 533                 case VM_PAGER_BAD:
 534                         /*
 535                          * Page outside of range of object. Right now we
 536                          * essentially lose the changes by pretending it
 537                          * worked.
 538                          */
 539                         vm_page_undirty(mt);
 540                         break;
 541                 case VM_PAGER_ERROR:
 542                 case VM_PAGER_FAIL:
 543                         /*
 544                          * If page couldn't be paged out, then reactivate the
 545                          * page so it doesn't clog the inactive list.  (We
 546                          * will try paging out it again later).
 547                          */
 548                         vm_page_lock(mt);
 549                         vm_page_activate(mt);
 550                         vm_page_unlock(mt);
 551                         if (eio != NULL && i >= mreq && i - mreq < runlen)
 552                                 *eio = TRUE;
 553                         break;
 554                 case VM_PAGER_AGAIN:
 555                         if (i >= mreq && i - mreq < runlen)
 556                                 runlen = i - mreq;
 557                         break;
 558                 }
 559
 560                 /*
 561                  * If the operation is still going, leave the page busy to
 562                  * block all other accesses. Also, leave the paging in
 563                  * progress indicator set so that we don't attempt an object
 564                  * collapse.
 565                  */
 566                 if (pageout_status[i] != VM_PAGER_PEND) {
 567                         vm_object_pip_wakeup(object);
 568                         vm_page_sunbusy(mt);
 569                 }
 570         }
 571         if (prunlen != NULL)
 572                 *prunlen = runlen;
 573         return (numpagedout);
 574 }
 575
 576 static boolean_t
 577 vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low,
 578     vm_paddr_t high)
 579 {
 580         struct mount *mp;
 581         struct vnode *vp;
 582         vm_object_t object;
 583         vm_paddr_t pa;
 584         vm_page_t m, m_tmp, next;
 585         int lockmode;
 586
 587         vm_pagequeue_lock(pq);
 588         TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) {
 589                 if ((m->flags & PG_MARKER) != 0)
 590                         continue;
 591                 pa = VM_PAGE_TO_PHYS(m);
 592                 if (pa < low || pa + PAGE_SIZE > high)
 593                         continue;
 594                 if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) {
 595                         vm_page_unlock(m);
 596                         continue;
 597                 }
 598                 object = m->object;
 599                 if ((!VM_OBJECT_TRYWLOCK(object) &&
 600                     (!vm_pageout_fallback_object_lock(m, &next) ||
 601                     m->hold_count != 0)) || vm_page_busied(m)) {
 602                         vm_page_unlock(m);
 603                         VM_OBJECT_WUNLOCK(object);
 604                         continue;
 605                 }
 606                 vm_page_test_dirty(m);
 607                 if (m->dirty == 0 && object->ref_count != 0)
 608                         pmap_remove_all(m);
 609                 if (m->dirty != 0) {
 610                         vm_page_unlock(m);
 611                         if (tries == 0 || (object->flags & OBJ_DEAD) != 0) {
 612                                 VM_OBJECT_WUNLOCK(object);
 613                                 continue;
 614                         }
 615                         if (object->type == OBJT_VNODE) {
 616                                 vm_pagequeue_unlock(pq);
 617                                 vp = object->handle;
 618                                 vm_object_reference_locked(object);
 619                                 VM_OBJECT_WUNLOCK(object);
 620                                 (void)vn_start_write(vp, &mp, V_WAIT);
 621                                 lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
 622                                     LK_SHARED : LK_EXCLUSIVE;
 623                                 vn_lock(vp, lockmode | LK_RETRY);
 624                                 VM_OBJECT_WLOCK(object);
 625                                 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
 626                                 VM_OBJECT_WUNLOCK(object);
 627                                 VOP_UNLOCK(vp, 0);
 628                                 vm_object_deallocate(object);
 629                                 vn_finished_write(mp);
 630                                 return (TRUE);
 631                         } else if (object->type == OBJT_SWAP ||
 632                             object->type == OBJT_DEFAULT) {
 633                                 vm_pagequeue_unlock(pq);
 634                                 m_tmp = m;
 635                                 vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC,
 636                                     0, NULL, NULL);
 637                                 VM_OBJECT_WUNLOCK(object);
 638                                 return (TRUE);
 639                         }
 640                 } else {
 641                         /*
 642                          * Dequeue here to prevent lock recursion in
 643                          * vm_page_cache().
 644                          */
 645                         vm_page_dequeue_locked(m);
 646                         vm_page_cache(m);
 647                         vm_page_unlock(m);
 648                 }
 649                 VM_OBJECT_WUNLOCK(object);
 650         }
 651         vm_pagequeue_unlock(pq);
 652         return (FALSE);
 653 }
 654
 655 /*
 656  * Increase the number of cached pages.  The specified value, "tries",
 657  * determines which categories of pages are cached:
 658  *
 659  *  0: All clean, inactive pages within the specified physical address range
 660  *     are cached.  Will not sleep.
 661  *  1: The vm_lowmem handlers are called.  All inactive pages within
 662  *     the specified physical address range are cached.  May sleep.
 663  *  2: The vm_lowmem handlers are called.  All inactive and active pages
 664  *     within the specified physical address range are cached.  May sleep.
 665  */
 666 void
 667 vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high)
 668 {
 669         int actl, actmax, inactl, inactmax, dom, initial_dom;
 670         static int start_dom = 0;
 671
 672         if (tries > 0) {
 673                 /*
 674                  * Decrease registered cache sizes.  The vm_lowmem handlers
 675                  * may acquire locks and/or sleep, so they can only be invoked
 676                  * when "tries" is greater than zero.
 677                  */
 678                 SDT_PROBE0(vm, , , vm__lowmem_cache);
 679                 EVENTHANDLER_INVOKE(vm_lowmem, 0);
 680
 681                 /*
 682                  * We do this explicitly after the caches have been drained
 683                  * above.
 684                  */
 685                 uma_reclaim();
 686         }
 687
 688         /*
 689          * Make the next scan start on the next domain.
 690          */
 691         initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains;
 692
 693         inactl = 0;
 694         inactmax = vm_cnt.v_inactive_count;
 695         actl = 0;
 696         actmax = tries < 2 ? 0 : vm_cnt.v_active_count;
 697         dom = initial_dom;
 698
 699         /*
 700          * Scan domains in round-robin order, first inactive queues,
 701          * then active.  Since domain usually owns large physically
 702          * contiguous chunk of memory, it makes sense to completely
 703          * exhaust one domain before switching to next, while growing
 704          * the pool of contiguous physical pages.
 705          *
 706          * Do not even start launder a domain which cannot contain
 707          * the specified address range, as indicated by segments
 708          * constituting the domain.
 709          */
 710 again:
 711         if (inactl < inactmax) {
 712                 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
 713                     low, high) &&
 714                     vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE],
 715                     tries, low, high)) {
 716                         inactl++;
 717                         goto again;
 718                 }
 719                 if (++dom == vm_ndomains)
 720                         dom = 0;
 721                 if (dom != initial_dom)
 722                         goto again;
 723         }
 724         if (actl < actmax) {
 725                 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
 726                     low, high) &&
 727                     vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE],
 728                       tries, low, high)) {
 729                         actl++;
 730                         goto again;
 731                 }
 732                 if (++dom == vm_ndomains)
 733                         dom = 0;
 734                 if (dom != initial_dom)
 735                         goto again;
 736         }
 737 }
 738
 739 #if !defined(NO_SWAPPING)
 740 /*
 741  *      vm_pageout_object_deactivate_pages
 742  *
 743  *      Deactivate enough pages to satisfy the inactive target
 744  *      requirements.
 745  *
 746  *      The object and map must be locked.
 747  */
 748 static void
 749 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
 750     long desired)
 751 {
 752         vm_object_t backing_object, object;
 753         vm_page_t p;
 754         int act_delta, remove_mode;
 755
 756         VM_OBJECT_ASSERT_LOCKED(first_object);
 757         if ((first_object->flags & OBJ_FICTITIOUS) != 0)
 758                 return;
 759         for (object = first_object;; object = backing_object) {
 760                 if (pmap_resident_count(pmap) <= desired)
 761                         goto unlock_return;
 762                 VM_OBJECT_ASSERT_LOCKED(object);
 763                 if ((object->flags & OBJ_UNMANAGED) != 0 ||
 764                     object->paging_in_progress != 0)
 765                         goto unlock_return;
 766
 767                 remove_mode = 0;
 768                 if (object->shadow_count > 1)
 769                         remove_mode = 1;
 770                 /*
 771                  * Scan the object's entire memory queue.
 772                  */
 773                 TAILQ_FOREACH(p, &object->memq, listq) {
 774                         if (pmap_resident_count(pmap) <= desired)
 775                                 goto unlock_return;
 776                         if (vm_page_busied(p))
 777                                 continue;
 778                         PCPU_INC(cnt.v_pdpages);
 779                         vm_page_lock(p);
 780                         if (p->wire_count != 0 || p->hold_count != 0 ||
 781                             !pmap_page_exists_quick(pmap, p)) {
 782                                 vm_page_unlock(p);
 783                                 continue;
 784                         }
 785                         act_delta = pmap_ts_referenced(p);
 786                         if ((p->aflags & PGA_REFERENCED) != 0) {
 787                                 if (act_delta == 0)
 788                                         act_delta = 1;
 789                                 vm_page_aflag_clear(p, PGA_REFERENCED);
 790                         }
 791                         if (p->queue != PQ_ACTIVE && act_delta != 0) {
 792                                 vm_page_activate(p);
 793                                 p->act_count += act_delta;
 794                         } else if (p->queue == PQ_ACTIVE) {
 795                                 if (act_delta == 0) {
 796                                         p->act_count -= min(p->act_count,
 797                                             ACT_DECLINE);
 798                                         if (!remove_mode && p->act_count == 0) {
 799                                                 pmap_remove_all(p);
 800                                                 vm_page_deactivate(p);
 801                                         } else
 802                                                 vm_page_requeue(p);
 803                                 } else {
 804                                         vm_page_activate(p);
 805                                         if (p->act_count < ACT_MAX -
 806                                             ACT_ADVANCE)
 807                                                 p->act_count += ACT_ADVANCE;
 808                                         vm_page_requeue(p);
 809                                 }
 810                         } else if (p->queue == PQ_INACTIVE)
 811                                 pmap_remove_all(p);
 812                         vm_page_unlock(p);
 813                 }
 814                 if ((backing_object = object->backing_object) == NULL)
 815                         goto unlock_return;
 816                 VM_OBJECT_RLOCK(backing_object);
 817                 if (object != first_object)
 818                         VM_OBJECT_RUNLOCK(object);
 819         }
 820 unlock_return:
 821         if (object != first_object)
 822                 VM_OBJECT_RUNLOCK(object);
 823 }
 824
 825 /*
 826  * deactivate some number of pages in a map, try to do it fairly, but
 827  * that is really hard to do.
 828  */
 829 static void
 830 vm_pageout_map_deactivate_pages(map, desired)
 831         vm_map_t map;
 832         long desired;
 833 {
 834         vm_map_entry_t tmpe;
 835         vm_object_t obj, bigobj;
 836         int nothingwired;
 837
 838         if (!vm_map_trylock(map))
 839                 return;
 840
 841         bigobj = NULL;
 842         nothingwired = TRUE;
 843
 844         /*
 845          * first, search out the biggest object, and try to free pages from
 846          * that.
 847          */
 848         tmpe = map->header.next;
 849         while (tmpe != &map->header) {
 850                 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
 851                         obj = tmpe->object.vm_object;
 852                         if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
 853                                 if (obj->shadow_count <= 1 &&
 854                                     (bigobj == NULL ||
 855                                      bigobj->resident_page_count < obj->resident_page_count)) {
 856                                         if (bigobj != NULL)
 857                                                 VM_OBJECT_RUNLOCK(bigobj);
 858                                         bigobj = obj;
 859                                 } else
 860                                         VM_OBJECT_RUNLOCK(obj);
 861                         }
 862                 }
 863                 if (tmpe->wired_count > 0)
 864                         nothingwired = FALSE;
 865                 tmpe = tmpe->next;
 866         }
 867
 868         if (bigobj != NULL) {
 869                 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
 870                 VM_OBJECT_RUNLOCK(bigobj);
 871         }
 872         /*
 873          * Next, hunt around for other pages to deactivate.  We actually
 874          * do this search sort of wrong -- .text first is not the best idea.
 875          */
 876         tmpe = map->header.next;
 877         while (tmpe != &map->header) {
 878                 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
 879                         break;
 880                 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
 881                         obj = tmpe->object.vm_object;
 882                         if (obj != NULL) {
 883                                 VM_OBJECT_RLOCK(obj);
 884                                 vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
 885                                 VM_OBJECT_RUNLOCK(obj);
 886                         }
 887                 }
 888                 tmpe = tmpe->next;
 889         }
 890
 891         /*
 892          * Remove all mappings if a process is swapped out, this will free page
 893          * table pages.
 894          */
 895         if (desired == 0 && nothingwired) {
 896                 pmap_remove(vm_map_pmap(map), vm_map_min(map),
 897                     vm_map_max(map));
 898         }
 899
 900         vm_map_unlock(map);
 901 }
 902 #endif          /* !defined(NO_SWAPPING) */
 903
 904 /*
 905  * Attempt to acquire all of the necessary locks to launder a page and
 906  * then call through the clustering layer to PUTPAGES.  Wait a short
 907  * time for a vnode lock.
 908  *
 909  * Requires the page and object lock on entry, releases both before return.
 910  * Returns 0 on success and an errno otherwise.
 911  */
 912 static int
 913 vm_pageout_clean(vm_page_t m)
 914 {
 915         struct vnode *vp;
 916         struct mount *mp;
 917         vm_object_t object;
 918         vm_pindex_t pindex;
 919         int error, lockmode;
 920
 921         vm_page_assert_locked(m);
 922         object = m->object;
 923         VM_OBJECT_ASSERT_WLOCKED(object);
 924         error = 0;
 925         vp = NULL;
 926         mp = NULL;
 927
 928         /*
 929          * The object is already known NOT to be dead.   It
 930          * is possible for the vget() to block the whole
 931          * pageout daemon, but the new low-memory handling
 932          * code should prevent it.
 933          *
 934          * We can't wait forever for the vnode lock, we might
 935          * deadlock due to a vn_read() getting stuck in
 936          * vm_wait while holding this vnode.  We skip the
 937          * vnode if we can't get it in a reasonable amount
 938          * of time.
 939          */
 940         if (object->type == OBJT_VNODE) {
 941                 vm_page_unlock(m);
 942                 vp = object->handle;
 943                 if (vp->v_type == VREG &&
 944                     vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 945                         mp = NULL;
 946                         error = EDEADLK;
 947                         goto unlock_all;
 948                 }
 949                 KASSERT(mp != NULL,
 950                     ("vp %p with NULL v_mount", vp));
 951                 vm_object_reference_locked(object);
 952                 pindex = m->pindex;
 953                 VM_OBJECT_WUNLOCK(object);
 954                 lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
 955                     LK_SHARED : LK_EXCLUSIVE;
 956                 if (vget(vp, lockmode | LK_TIMELOCK, curthread)) {
 957                         vp = NULL;
 958                         error = EDEADLK;
 959                         goto unlock_mp;
 960                 }
 961                 VM_OBJECT_WLOCK(object);
 962                 vm_page_lock(m);
 963                 /*
 964                  * While the object and page were unlocked, the page
 965                  * may have been:
 966                  * (1) moved to a different queue,
 967                  * (2) reallocated to a different object,
 968                  * (3) reallocated to a different offset, or
 969                  * (4) cleaned.
 970                  */
 971                 if (m->queue != PQ_INACTIVE || m->object != object ||
 972                     m->pindex != pindex || m->dirty == 0) {
 973                         vm_page_unlock(m);
 974                         error = ENXIO;
 975                         goto unlock_all;
 976                 }
 977
 978                 /*
 979                  * The page may have been busied or held while the object
 980                  * and page locks were released.
 981                  */
 982                 if (vm_page_busied(m) || m->hold_count != 0) {
 983                         vm_page_unlock(m);
 984                         error = EBUSY;
 985                         goto unlock_all;
 986                 }
 987         }
 988
 989         /*
 990          * If a page is dirty, then it is either being washed
 991          * (but not yet cleaned) or it is still in the
 992          * laundry.  If it is still in the laundry, then we
 993          * start the cleaning operation.
 994          */
 995         if (vm_pageout_cluster(m) == 0)
 996                 error = EIO;
 997
 998 unlock_all:
 999         VM_OBJECT_WUNLOCK(object);
1000
1001 unlock_mp:
1002         vm_page_lock_assert(m, MA_NOTOWNED);
1003         if (mp != NULL) {
1004                 if (vp != NULL)
1005                         vput(vp);
1006                 vm_object_deallocate(object);
1007                 vn_finished_write(mp);
1008         }
1009
1010         return (error);
1011 }
1012
1013 /*
1014  *      vm_pageout_scan does the dirty work for the pageout daemon.
1015  *
1016  *      pass 0 - Update active LRU/deactivate pages
1017  *      pass 1 - Move inactive to cache or free
1018  *      pass 2 - Launder dirty pages
1019  */
1020 static void
1021 vm_pageout_scan(struct vm_domain *vmd, int pass)
1022 {
1023         vm_page_t m, next;
1024         struct vm_pagequeue *pq;
1025         vm_object_t object;
1026         long min_scan;
1027         int act_delta, addl_page_shortage, deficit, maxscan, page_shortage;
1028         int vnodes_skipped = 0;
1029         int maxlaunder, scan_tick, scanned;
1030         boolean_t queues_locked;
1031
1032         /*
1033          * If we need to reclaim memory ask kernel caches to return
1034          * some.  We rate limit to avoid thrashing.
1035          */
1036         if (vmd == &vm_dom[0] && pass > 0 &&
1037             (ticks - lowmem_ticks) / hz >= lowmem_period) {
1038                 /*
1039                  * Decrease registered cache sizes.
1040                  */
1041                 SDT_PROBE0(vm, , , vm__lowmem_scan);
1042                 EVENTHANDLER_INVOKE(vm_lowmem, 0);
1043                 /*
1044                  * We do this explicitly after the caches have been
1045                  * drained above.
1046                  */
1047                 uma_reclaim();
1048                 lowmem_ticks = ticks;
1049         }
1050
1051         /*
1052          * The addl_page_shortage is the number of temporarily
1053          * stuck pages in the inactive queue.  In other words, the
1054          * number of pages from the inactive count that should be
1055          * discounted in setting the target for the active queue scan.
1056          */
1057         addl_page_shortage = 0;
1058
1059         /*
1060          * Calculate the number of pages we want to either free or move
1061          * to the cache.
1062          */
1063         if (pass > 0) {
1064                 deficit = atomic_readandclear_int(&vm_pageout_deficit);
1065                 page_shortage = vm_paging_target() + deficit;
1066         } else
1067                 page_shortage = deficit = 0;
1068
1069         /*
1070          * maxlaunder limits the number of dirty pages we flush per scan.
1071          * For most systems a smaller value (16 or 32) is more robust under
1072          * extreme memory and disk pressure because any unnecessary writes
1073          * to disk can result in extreme performance degredation.  However,
1074          * systems with excessive dirty pages (especially when MAP_NOSYNC is
1075          * used) will die horribly with limited laundering.  If the pageout
1076          * daemon cannot clean enough pages in the first pass, we let it go
1077          * all out in succeeding passes.
1078          */
1079         if ((maxlaunder = vm_max_launder) <= 1)
1080                 maxlaunder = 1;
1081         if (pass > 1)
1082                 maxlaunder = 10000;
1083
1084         /*
1085          * Start scanning the inactive queue for pages we can move to the
1086          * cache or free.  The scan will stop when the target is reached or
1087          * we have scanned the entire inactive queue.  Note that m->act_count
1088          * is not used to form decisions for the inactive queue, only for the
1089          * active queue.
1090          */
1091         pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
1092         maxscan = pq->pq_cnt;
1093         vm_pagequeue_lock(pq);
1094         queues_locked = TRUE;
1095         for (m = TAILQ_FIRST(&pq->pq_pl);
1096              m != NULL && maxscan-- > 0 && page_shortage > 0;
1097              m = next) {
1098                 vm_pagequeue_assert_locked(pq);
1099                 KASSERT(queues_locked, ("unlocked queues"));
1100                 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m));
1101
1102                 PCPU_INC(cnt.v_pdpages);
1103                 next = TAILQ_NEXT(m, plinks.q);
1104
1105                 /*
1106                  * skip marker pages
1107                  */
1108                 if (m->flags & PG_MARKER)
1109                         continue;
1110
1111                 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1112                     ("Fictitious page %p cannot be in inactive queue", m));
1113                 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1114                     ("Unmanaged page %p cannot be in inactive queue", m));
1115
1116                 /*
1117                  * The page or object lock acquisitions fail if the
1118                  * page was removed from the queue or moved to a
1119                  * different position within the queue.  In either
1120                  * case, addl_page_shortage should not be incremented.
1121                  */
1122                 if (!vm_pageout_page_lock(m, &next)) {
1123                         vm_page_unlock(m);
1124                         continue;
1125                 }
1126                 object = m->object;
1127                 if (!VM_OBJECT_TRYWLOCK(object) &&
1128                     !vm_pageout_fallback_object_lock(m, &next)) {
1129                         vm_page_unlock(m);
1130                         VM_OBJECT_WUNLOCK(object);
1131                         continue;
1132                 }
1133
1134                 /*
1135                  * Don't mess with busy pages, keep them at at the
1136                  * front of the queue, most likely they are being
1137                  * paged out.  Increment addl_page_shortage for busy
1138                  * pages, because they may leave the inactive queue
1139                  * shortly after page scan is finished.
1140                  */
1141                 if (vm_page_busied(m)) {
1142                         vm_page_unlock(m);
1143                         VM_OBJECT_WUNLOCK(object);
1144                         addl_page_shortage++;
1145                         continue;
1146                 }
1147
1148                 /*
1149                  * We unlock the inactive page queue, invalidating the
1150                  * 'next' pointer.  Use our marker to remember our
1151                  * place.
1152                  */
1153                 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q);
1154                 vm_pagequeue_unlock(pq);
1155                 queues_locked = FALSE;
1156
1157                 /*
1158                  * Invalid pages can be easily freed. They cannot be
1159                  * mapped, vm_page_free() asserts this.
1160                  */
1161                 if (m->valid == 0 && m->hold_count == 0) {
1162                         vm_page_free(m);
1163                         PCPU_INC(cnt.v_dfree);
1164                         --page_shortage;
1165                         goto drop_page;
1166                 }
1167
1168                 /*
1169                  * We bump the activation count if the page has been
1170                  * referenced while in the inactive queue.  This makes
1171                  * it less likely that the page will be added back to the
1172                  * inactive queue prematurely again.  Here we check the
1173                  * page tables (or emulated bits, if any), given the upper
1174                  * level VM system not knowing anything about existing
1175                  * references.
1176                  */
1177                 if ((m->aflags & PGA_REFERENCED) != 0) {
1178                         vm_page_aflag_clear(m, PGA_REFERENCED);
1179                         act_delta = 1;
1180                 } else
1181                         act_delta = 0;
1182                 if (object->ref_count != 0) {
1183                         act_delta += pmap_ts_referenced(m);
1184                 } else {
1185                         KASSERT(!pmap_page_is_mapped(m),
1186                             ("vm_pageout_scan: page %p is mapped", m));
1187                 }
1188
1189                 /*
1190                  * If the upper level VM system knows about any page
1191                  * references, we reactivate the page or requeue it.
1192                  */
1193                 if (act_delta != 0) {
1194                         if (object->ref_count != 0) {
1195                                 vm_page_activate(m);
1196                                 m->act_count += act_delta + ACT_ADVANCE;
1197                         } else {
1198                                 vm_pagequeue_lock(pq);
1199                                 queues_locked = TRUE;
1200                                 vm_page_requeue_locked(m);
1201                         }
1202                         goto drop_page;
1203                 }
1204
1205                 if (m->hold_count != 0) {
1206                         /*
1207                          * Held pages are essentially stuck in the
1208                          * queue.  So, they ought to be discounted
1209                          * from the inactive count.  See the
1210                          * calculation of the page_shortage for the
1211                          * loop over the active queue below.
1212                          */
1213                         addl_page_shortage++;
1214                         goto drop_page;
1215                 }
1216
1217                 /*
1218                  * If the page appears to be clean at the machine-independent
1219                  * layer, then remove all of its mappings from the pmap in
1220                  * anticipation of placing it onto the cache queue.  If,
1221                  * however, any of the page's mappings allow write access,
1222                  * then the page may still be modified until the last of those
1223                  * mappings are removed.
1224                  */
1225                 if (object->ref_count != 0) {
1226                         vm_page_test_dirty(m);
1227                         if (m->dirty == 0)
1228                                 pmap_remove_all(m);
1229                 }
1230
1231                 if (m->dirty == 0) {
1232                         /*
1233                          * Clean pages can be freed.
1234                          */
1235                         vm_page_free(m);
1236                         PCPU_INC(cnt.v_dfree);
1237                         --page_shortage;
1238                 } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) {
1239                         /*
1240                          * Dirty pages need to be paged out, but flushing
1241                          * a page is extremely expensive versus freeing
1242                          * a clean page.  Rather then artificially limiting
1243                          * the number of pages we can flush, we instead give
1244                          * dirty pages extra priority on the inactive queue
1245                          * by forcing them to be cycled through the queue
1246                          * twice before being flushed, after which the
1247                          * (now clean) page will cycle through once more
1248                          * before being freed.  This significantly extends
1249                          * the thrash point for a heavily loaded machine.
1250                          */
1251                         m->flags |= PG_WINATCFLS;
1252                         vm_pagequeue_lock(pq);
1253                         queues_locked = TRUE;
1254                         vm_page_requeue_locked(m);
1255                 } else if (maxlaunder > 0) {
1256                         /*
1257                          * We always want to try to flush some dirty pages if
1258                          * we encounter them, to keep the system stable.
1259                          * Normally this number is small, but under extreme
1260                          * pressure where there are insufficient clean pages
1261                          * on the inactive queue, we may have to go all out.
1262                          */
1263                         int swap_pageouts_ok;
1264                         int error;
1265
1266                         if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
1267                                 swap_pageouts_ok = 1;
1268                         } else {
1269                                 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
1270                                 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
1271                                 vm_page_count_min());
1272
1273                         }
1274
1275                         /*
1276                          * We don't bother paging objects that are "dead".
1277                          * Those objects are in a "rundown" state.
1278                          */
1279                         if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
1280                                 vm_pagequeue_lock(pq);
1281                                 vm_page_unlock(m);
1282                                 VM_OBJECT_WUNLOCK(object);
1283                                 queues_locked = TRUE;
1284                                 vm_page_requeue_locked(m);
1285                                 goto relock_queues;
1286                         }
1287                         error = vm_pageout_clean(m);
1288                         /*
1289                          * Decrement page_shortage on success to account for
1290                          * the (future) cleaned page.  Otherwise we could wind
1291                          * up laundering or cleaning too many pages.
1292                          */
1293                         if (error == 0) {
1294                                 page_shortage--;
1295                                 maxlaunder--;
1296                         } else if (error == EDEADLK) {
1297                                 pageout_lock_miss++;
1298                                 vnodes_skipped++;
1299                         } else if (error == EBUSY) {
1300                                 addl_page_shortage++;
1301                         }
1302                         vm_page_lock_assert(m, MA_NOTOWNED);
1303                         goto relock_queues;
1304                 }
1305 drop_page:
1306                 vm_page_unlock(m);
1307                 VM_OBJECT_WUNLOCK(object);
1308 relock_queues:
1309                 if (!queues_locked) {
1310                         vm_pagequeue_lock(pq);
1311                         queues_locked = TRUE;
1312                 }
1313                 next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q);
1314                 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q);
1315         }
1316         vm_pagequeue_unlock(pq);
1317
1318 #if !defined(NO_SWAPPING)
1319         /*
1320          * Wakeup the swapout daemon if we didn't cache or free the targeted
1321          * number of pages.
1322          */
1323         if (vm_swap_enabled && page_shortage > 0)
1324                 vm_req_vmdaemon(VM_SWAP_NORMAL);
1325 #endif
1326
1327         /*
1328          * Wakeup the sync daemon if we skipped a vnode in a writeable object
1329          * and we didn't cache or free enough pages.
1330          */
1331         if (vnodes_skipped > 0 && page_shortage > vm_cnt.v_free_target -
1332             vm_cnt.v_free_min)
1333                 (void)speedup_syncer();
1334
1335         /*
1336          * Compute the number of pages we want to try to move from the
1337          * active queue to the inactive queue.
1338          */
1339         page_shortage = vm_cnt.v_inactive_target - vm_cnt.v_inactive_count +
1340             vm_paging_target() + deficit + addl_page_shortage;
1341
1342         pq = &vmd->vmd_pagequeues[PQ_ACTIVE];
1343         vm_pagequeue_lock(pq);
1344         maxscan = pq->pq_cnt;
1345
1346         /*
1347          * If we're just idle polling attempt to visit every
1348          * active page within 'update_period' seconds.
1349          */
1350         scan_tick = ticks;
1351         if (vm_pageout_update_period != 0) {
1352                 min_scan = pq->pq_cnt;
1353                 min_scan *= scan_tick - vmd->vmd_last_active_scan;
1354                 min_scan /= hz * vm_pageout_update_period;
1355         } else
1356                 min_scan = 0;
1357         if (min_scan > 0 || (page_shortage > 0 && maxscan > 0))
1358                 vmd->vmd_last_active_scan = scan_tick;
1359
1360         /*
1361          * Scan the active queue for pages that can be deactivated.  Update
1362          * the per-page activity counter and use it to identify deactivation
1363          * candidates.
1364          */
1365         for (m = TAILQ_FIRST(&pq->pq_pl), scanned = 0; m != NULL && (scanned <
1366             min_scan || (page_shortage > 0 && scanned < maxscan)); m = next,
1367             scanned++) {
1368
1369                 KASSERT(m->queue == PQ_ACTIVE,
1370                     ("vm_pageout_scan: page %p isn't active", m));
1371
1372                 next = TAILQ_NEXT(m, plinks.q);
1373                 if ((m->flags & PG_MARKER) != 0)
1374                         continue;
1375                 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1376                     ("Fictitious page %p cannot be in active queue", m));
1377                 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1378                     ("Unmanaged page %p cannot be in active queue", m));
1379                 if (!vm_pageout_page_lock(m, &next)) {
1380                         vm_page_unlock(m);
1381                         continue;
1382                 }
1383
1384                 /*
1385                  * The count for pagedaemon pages is done after checking the
1386                  * page for eligibility...
1387                  */
1388                 PCPU_INC(cnt.v_pdpages);
1389
1390                 /*
1391                  * Check to see "how much" the page has been used.
1392                  */
1393                 if ((m->aflags & PGA_REFERENCED) != 0) {
1394                         vm_page_aflag_clear(m, PGA_REFERENCED);
1395                         act_delta = 1;
1396                 } else
1397                         act_delta = 0;
1398
1399                 /*
1400                  * Unlocked object ref count check.  Two races are possible.
1401                  * 1) The ref was transitioning to zero and we saw non-zero,
1402                  *    the pmap bits will be checked unnecessarily.
1403                  * 2) The ref was transitioning to one and we saw zero.
1404                  *    The page lock prevents a new reference to this page so
1405                  *    we need not check the reference bits.
1406                  */
1407                 if (m->object->ref_count != 0)
1408                         act_delta += pmap_ts_referenced(m);
1409
1410                 /*
1411                  * Advance or decay the act_count based on recent usage.
1412                  */
1413                 if (act_delta != 0) {
1414                         m->act_count += ACT_ADVANCE + act_delta;
1415                         if (m->act_count > ACT_MAX)
1416                                 m->act_count = ACT_MAX;
1417                 } else
1418                         m->act_count -= min(m->act_count, ACT_DECLINE);
1419
1420                 /*
1421                  * Move this page to the tail of the active or inactive
1422                  * queue depending on usage.
1423                  */
1424                 if (m->act_count == 0) {
1425                         /* Dequeue to avoid later lock recursion. */
1426                         vm_page_dequeue_locked(m);
1427                         vm_page_deactivate(m);
1428                         page_shortage--;
1429                 } else
1430                         vm_page_requeue_locked(m);
1431                 vm_page_unlock(m);
1432         }
1433         vm_pagequeue_unlock(pq);
1434 #if !defined(NO_SWAPPING)
1435         /*
1436          * Idle process swapout -- run once per second.
1437          */
1438         if (vm_swap_idle_enabled) {
1439                 static long lsec;
1440                 if (time_second != lsec) {
1441                         vm_req_vmdaemon(VM_SWAP_IDLE);
1442                         lsec = time_second;
1443                 }
1444         }
1445 #endif
1446
1447         /*
1448          * If we are critically low on one of RAM or swap and low on
1449          * the other, kill the largest process.  However, we avoid
1450          * doing this on the first pass in order to give ourselves a
1451          * chance to flush out dirty vnode-backed pages and to allow
1452          * active pages to be moved to the inactive queue and reclaimed.
1453          */
1454         vm_pageout_mightbe_oom(vmd, pass);
1455 }
1456
1457 static int vm_pageout_oom_vote;
1458
1459 /*
1460  * The pagedaemon threads randlomly select one to perform the
1461  * OOM.  Trying to kill processes before all pagedaemons
1462  * failed to reach free target is premature.
1463  */
1464 static void
1465 vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass)
1466 {
1467         int old_vote;
1468
1469         if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) ||
1470             (swap_pager_full && vm_paging_target() > 0))) {
1471                 if (vmd->vmd_oom) {
1472                         vmd->vmd_oom = FALSE;
1473                         atomic_subtract_int(&vm_pageout_oom_vote, 1);
1474                 }
1475                 return;
1476         }
1477
1478         if (vmd->vmd_oom)
1479                 return;
1480
1481         vmd->vmd_oom = TRUE;
1482         old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1);
1483         if (old_vote != vm_ndomains - 1)
1484                 return;
1485
1486         /*
1487          * The current pagedaemon thread is the last in the quorum to
1488          * start OOM.  Initiate the selection and signaling of the
1489          * victim.
1490          */
1491         vm_pageout_oom(VM_OOM_MEM);
1492
1493         /*
1494          * After one round of OOM terror, recall our vote.  On the
1495          * next pass, current pagedaemon would vote again if the low
1496          * memory condition is still there, due to vmd_oom being
1497          * false.
1498          */
1499         vmd->vmd_oom = FALSE;
1500         atomic_subtract_int(&vm_pageout_oom_vote, 1);
1501 }
1502
1503 void
1504 vm_pageout_oom(int shortage)
1505 {
1506         struct proc *p, *bigproc;
1507         vm_offset_t size, bigsize;
1508         struct thread *td;
1509         struct vmspace *vm;
1510
1511         /*
1512          * We keep the process bigproc locked once we find it to keep anyone
1513          * from messing with it; however, there is a possibility of
1514          * deadlock if process B is bigproc and one of it's child processes
1515          * attempts to propagate a signal to B while we are waiting for A's
1516          * lock while walking this list.  To avoid this, we don't block on
1517          * the process lock but just skip a process if it is already locked.
1518          */
1519         bigproc = NULL;
1520         bigsize = 0;
1521         sx_slock(&allproc_lock);
1522         FOREACH_PROC_IN_SYSTEM(p) {
1523                 int breakout;
1524
1525                 PROC_LOCK(p);
1526
1527                 /*
1528                  * If this is a system, protected or killed process, skip it.
1529                  */
1530                 if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
1531                     P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 ||
1532                     p->p_pid == 1 || P_KILLED(p) ||
1533                     (p->p_pid < 48 && swap_pager_avail != 0)) {
1534                         PROC_UNLOCK(p);
1535                         continue;
1536                 }
1537                 /*
1538                  * If the process is in a non-running type state,
1539                  * don't touch it.  Check all the threads individually.
1540                  */
1541                 breakout = 0;
1542                 FOREACH_THREAD_IN_PROC(p, td) {
1543                         thread_lock(td);
1544                         if (!TD_ON_RUNQ(td) &&
1545                             !TD_IS_RUNNING(td) &&
1546                             !TD_IS_SLEEPING(td) &&
1547                             !TD_IS_SUSPENDED(td)) {
1548                                 thread_unlock(td);
1549                                 breakout = 1;
1550                                 break;
1551                         }
1552                         thread_unlock(td);
1553                 }
1554                 if (breakout) {
1555                         PROC_UNLOCK(p);
1556                         continue;
1557                 }
1558                 /*
1559                  * get the process size
1560                  */
1561                 vm = vmspace_acquire_ref(p);
1562                 if (vm == NULL) {
1563                         PROC_UNLOCK(p);
1564                         continue;
1565                 }
1566                 _PHOLD(p);
1567                 if (!vm_map_trylock_read(&vm->vm_map)) {
1568                         _PRELE(p);
1569                         PROC_UNLOCK(p);
1570                         vmspace_free(vm);
1571                         continue;
1572                 }
1573                 PROC_UNLOCK(p);
1574                 size = vmspace_swap_count(vm);
1575                 vm_map_unlock_read(&vm->vm_map);
1576                 if (shortage == VM_OOM_MEM)
1577                         size += vmspace_resident_count(vm);
1578                 vmspace_free(vm);
1579                 /*
1580                  * if the this process is bigger than the biggest one
1581                  * remember it.
1582                  */
1583                 if (size > bigsize) {
1584                         if (bigproc != NULL)
1585                                 PRELE(bigproc);
1586                         bigproc = p;
1587                         bigsize = size;
1588                 } else {
1589                         PRELE(p);
1590                 }
1591         }
1592         sx_sunlock(&allproc_lock);
1593         if (bigproc != NULL) {
1594                 if (vm_panic_on_oom != 0)
1595                         panic("out of swap space");
1596                 PROC_LOCK(bigproc);
1597                 killproc(bigproc, "out of swap space");
1598                 sched_nice(bigproc, PRIO_MIN);
1599                 _PRELE(bigproc);
1600                 PROC_UNLOCK(bigproc);
1601                 wakeup(&vm_cnt.v_free_count);
1602         }
1603 }
1604
1605 static void
1606 vm_pageout_worker(void *arg)
1607 {
1608         struct vm_domain *domain;
1609         int domidx;
1610
1611         domidx = (uintptr_t)arg;
1612         domain = &vm_dom[domidx];
1613
1614         /*
1615          * XXXKIB It could be useful to bind pageout daemon threads to
1616          * the cores belonging to the domain, from which vm_page_array
1617          * is allocated.
1618          */
1619
1620         KASSERT(domain->vmd_segs != 0, ("domain without segments"));
1621         domain->vmd_last_active_scan = ticks;
1622         vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE);
1623
1624         /*
1625          * The pageout daemon worker is never done, so loop forever.
1626          */
1627         while (TRUE) {
1628                 /*
1629                  * If we have enough free memory, wakeup waiters.  Do
1630                  * not clear vm_pages_needed until we reach our target,
1631                  * otherwise we may be woken up over and over again and
1632                  * waste a lot of cpu.
1633                  */
1634                 mtx_lock(&vm_page_queue_free_mtx);
1635                 if (vm_pages_needed && !vm_page_count_min()) {
1636                         if (!vm_paging_needed())
1637                                 vm_pages_needed = 0;
1638                         wakeup(&vm_cnt.v_free_count);
1639                 }
1640                 if (vm_pages_needed) {
1641                         /*
1642                          * Still not done, take a second pass without waiting
1643                          * (unlimited dirty cleaning), otherwise sleep a bit
1644                          * and try again.
1645                          */
1646                         if (domain->vmd_pass > 1)
1647                                 msleep(&vm_pages_needed,
1648                                     &vm_page_queue_free_mtx, PVM, "psleep",
1649                                     hz / 2);
1650                 } else {
1651                         /*
1652                          * Good enough, sleep until required to refresh
1653                          * stats.
1654                          */
1655                         domain->vmd_pass = 0;
1656                         msleep(&vm_pages_needed, &vm_page_queue_free_mtx,
1657                             PVM, "psleep", hz);
1658
1659                 }
1660                 if (vm_pages_needed) {
1661                         vm_cnt.v_pdwakeups++;
1662                         domain->vmd_pass++;
1663                 }
1664                 mtx_unlock(&vm_page_queue_free_mtx);
1665                 vm_pageout_scan(domain, domain->vmd_pass);
1666         }
1667 }
1668
1669 /*
1670  *      vm_pageout_init initialises basic pageout daemon settings.
1671  */
1672 static void
1673 vm_pageout_init(void)
1674 {
1675         /*
1676          * Initialize some paging parameters.
1677          */
1678         vm_cnt.v_interrupt_free_min = 2;
1679         if (vm_cnt.v_page_count < 2000)
1680                 vm_pageout_page_count = 8;
1681
1682         /*
1683          * v_free_reserved needs to include enough for the largest
1684          * swap pager structures plus enough for any pv_entry structs
1685          * when paging.
1686          */
1687         if (vm_cnt.v_page_count > 1024)
1688                 vm_cnt.v_free_min = 4 + (vm_cnt.v_page_count - 1024) / 200;
1689         else
1690                 vm_cnt.v_free_min = 4;
1691         vm_cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1692             vm_cnt.v_interrupt_free_min;
1693         vm_cnt.v_free_reserved = vm_pageout_page_count +
1694             vm_cnt.v_pageout_free_min + (vm_cnt.v_page_count / 768);
1695         vm_cnt.v_free_severe = vm_cnt.v_free_min / 2;
1696         vm_cnt.v_free_target = 4 * vm_cnt.v_free_min + vm_cnt.v_free_reserved;
1697         vm_cnt.v_free_min += vm_cnt.v_free_reserved;
1698         vm_cnt.v_free_severe += vm_cnt.v_free_reserved;
1699         vm_cnt.v_inactive_target = (3 * vm_cnt.v_free_target) / 2;
1700         if (vm_cnt.v_inactive_target > vm_cnt.v_free_count / 3)
1701                 vm_cnt.v_inactive_target = vm_cnt.v_free_count / 3;
1702
1703         /*
1704          * Set the default wakeup threshold to be 10% above the minimum
1705          * page limit.  This keeps the steady state out of shortfall.
1706          */
1707         vm_pageout_wakeup_thresh = (vm_cnt.v_free_min / 10) * 11;
1708
1709         /*
1710          * Set interval in seconds for active scan.  We want to visit each
1711          * page at least once every ten minutes.  This is to prevent worst
1712          * case paging behaviors with stale active LRU.
1713          */
1714         if (vm_pageout_update_period == 0)
1715                 vm_pageout_update_period = 600;
1716
1717         /* XXX does not really belong here */
1718         if (vm_page_max_wired == 0)
1719                 vm_page_max_wired = vm_cnt.v_free_count / 3;
1720 }
1721
1722 /*
1723  *     vm_pageout is the high level pageout daemon.
1724  */
1725 static void
1726 vm_pageout(void)
1727 {
1728         int error;
1729 #if MAXMEMDOM > 1
1730         int i;
1731 #endif
1732
1733         swap_pager_swap_init();
1734 #if MAXMEMDOM > 1
1735         for (i = 1; i < vm_ndomains; i++) {
1736                 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i,
1737                     curproc, NULL, 0, 0, "dom%d", i);
1738                 if (error != 0) {
1739                         panic("starting pageout for domain %d, error %d\n",
1740                             i, error);
1741                 }
1742         }
1743 #endif
1744         error = kthread_add(uma_reclaim_worker, NULL, curproc, NULL,
1745             0, 0, "uma");
1746         if (error != 0)
1747                 panic("starting uma_reclaim helper, error %d\n", error);
1748         vm_pageout_worker((void *)(uintptr_t)0);
1749 }
1750
1751 /*
1752  * Unless the free page queue lock is held by the caller, this function
1753  * should be regarded as advisory.  Specifically, the caller should
1754  * not msleep() on &vm_cnt.v_free_count following this function unless
1755  * the free page queue lock is held until the msleep() is performed.
1756  */
1757 void
1758 pagedaemon_wakeup(void)
1759 {
1760
1761         if (!vm_pages_needed && curthread->td_proc != pageproc) {
1762                 vm_pages_needed = 1;
1763                 wakeup(&vm_pages_needed);
1764         }
1765 }
1766
1767 #if !defined(NO_SWAPPING)
1768 static void
1769 vm_req_vmdaemon(int req)
1770 {
1771         static int lastrun = 0;
1772
1773         mtx_lock(&vm_daemon_mtx);
1774         vm_pageout_req_swapout |= req;
1775         if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1776                 wakeup(&vm_daemon_needed);
1777                 lastrun = ticks;
1778         }
1779         mtx_unlock(&vm_daemon_mtx);
1780 }
1781
1782 static void
1783 vm_daemon(void)
1784 {
1785         struct rlimit rsslim;
1786         struct proc *p;
1787         struct thread *td;
1788         struct vmspace *vm;
1789         int breakout, swapout_flags, tryagain, attempts;
1790 #ifdef RACCT
1791         uint64_t rsize, ravailable;
1792 #endif
1793
1794         while (TRUE) {
1795                 mtx_lock(&vm_daemon_mtx);
1796                 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
1797 #ifdef RACCT
1798                     racct_enable ? hz : 0
1799 #else
1800                     0
1801 #endif
1802                 );
1803                 swapout_flags = vm_pageout_req_swapout;
1804                 vm_pageout_req_swapout = 0;
1805                 mtx_unlock(&vm_daemon_mtx);
1806                 if (swapout_flags)
1807                         swapout_procs(swapout_flags);
1808
1809                 /*
1810                  * scan the processes for exceeding their rlimits or if
1811                  * process is swapped out -- deactivate pages
1812                  */
1813                 tryagain = 0;
1814                 attempts = 0;
1815 again:
1816                 attempts++;
1817                 sx_slock(&allproc_lock);
1818                 FOREACH_PROC_IN_SYSTEM(p) {
1819                         vm_pindex_t limit, size;
1820
1821                         /*
1822                          * if this is a system process or if we have already
1823                          * looked at this process, skip it.
1824                          */
1825                         PROC_LOCK(p);
1826                         if (p->p_state != PRS_NORMAL ||
1827                             p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
1828                                 PROC_UNLOCK(p);
1829                                 continue;
1830                         }
1831                         /*
1832                          * if the process is in a non-running type state,
1833                          * don't touch it.
1834                          */
1835                         breakout = 0;
1836                         FOREACH_THREAD_IN_PROC(p, td) {
1837                                 thread_lock(td);
1838                                 if (!TD_ON_RUNQ(td) &&
1839                                     !TD_IS_RUNNING(td) &&
1840                                     !TD_IS_SLEEPING(td) &&
1841                                     !TD_IS_SUSPENDED(td)) {
1842                                         thread_unlock(td);
1843                                         breakout = 1;
1844                                         break;
1845                                 }
1846                                 thread_unlock(td);
1847                         }
1848                         if (breakout) {
1849                                 PROC_UNLOCK(p);
1850                                 continue;
1851                         }
1852                         /*
1853                          * get a limit
1854                          */
1855                         lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
1856                         limit = OFF_TO_IDX(
1857                             qmin(rsslim.rlim_cur, rsslim.rlim_max));
1858
1859                         /*
1860                          * let processes that are swapped out really be
1861                          * swapped out set the limit to nothing (will force a
1862                          * swap-out.)
1863                          */
1864                         if ((p->p_flag & P_INMEM) == 0)
1865                                 limit = 0;      /* XXX */
1866                         vm = vmspace_acquire_ref(p);
1867                         PROC_UNLOCK(p);
1868                         if (vm == NULL)
1869                                 continue;
1870
1871                         size = vmspace_resident_count(vm);
1872                         if (size >= limit) {
1873                                 vm_pageout_map_deactivate_pages(
1874                                     &vm->vm_map, limit);
1875                         }
1876 #ifdef RACCT
1877                         if (racct_enable) {
1878                                 rsize = IDX_TO_OFF(size);
1879                                 PROC_LOCK(p);
1880                                 racct_set(p, RACCT_RSS, rsize);
1881                                 ravailable = racct_get_available(p, RACCT_RSS);
1882                                 PROC_UNLOCK(p);
1883                                 if (rsize > ravailable) {
1884                                         /*
1885                                          * Don't be overly aggressive; this
1886                                          * might be an innocent process,
1887                                          * and the limit could've been exceeded
1888                                          * by some memory hog.  Don't try
1889                                          * to deactivate more than 1/4th
1890                                          * of process' resident set size.
1891                                          */
1892                                         if (attempts <= 8) {
1893                                                 if (ravailable < rsize -
1894                                                     (rsize / 4)) {
1895                                                         ravailable = rsize -
1896                                                             (rsize / 4);
1897                                                 }
1898                                         }
1899                                         vm_pageout_map_deactivate_pages(
1900                                             &vm->vm_map,
1901                                             OFF_TO_IDX(ravailable));
1902                                         /* Update RSS usage after paging out. */
1903                                         size = vmspace_resident_count(vm);
1904                                         rsize = IDX_TO_OFF(size);
1905                                         PROC_LOCK(p);
1906                                         racct_set(p, RACCT_RSS, rsize);
1907                                         PROC_UNLOCK(p);
1908                                         if (rsize > ravailable)
1909                                                 tryagain = 1;
1910                                 }
1911                         }
1912 #endif
1913                         vmspace_free(vm);
1914                 }
1915                 sx_sunlock(&allproc_lock);
1916                 if (tryagain != 0 && attempts <= 10)
1917                         goto again;
1918         }
1919 }
1920 #endif                  /* !defined(NO_SWAPPING) */