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