2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
4 * Copyright (c) 1991 Regents of the University of California.
6 * Copyright (c) 1994 John S. Dyson
8 * Copyright (c) 1994 David Greenman
10 * Copyright (c) 2005 Yahoo! Technologies Norway AS
11 * All rights reserved.
13 * This code is derived from software contributed to Berkeley by
14 * The Mach Operating System project at Carnegie-Mellon University.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 * 3. All advertising materials mentioning features or use of this software
25 * must display the following acknowledgement:
26 * This product includes software developed by the University of
27 * California, Berkeley and its contributors.
28 * 4. Neither the name of the University nor the names of its contributors
29 * may be used to endorse or promote products derived from this software
30 * without specific prior written permission.
32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
47 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
48 * All rights reserved.
50 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
52 * Permission to use, copy, modify and distribute this software and
53 * its documentation is hereby granted, provided that both the copyright
54 * notice and this permission notice appear in all copies of the
55 * software, derivative works or modified versions, and any portions
56 * thereof, and that both notices appear in supporting documentation.
58 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
59 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
60 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
62 * Carnegie Mellon requests users of this software to return to
64 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
65 * School of Computer Science
66 * Carnegie Mellon University
67 * Pittsburgh PA 15213-3890
69 * any improvements or extensions that they make and grant Carnegie the
70 * rights to redistribute these changes.
73 #include <sys/cdefs.h>
74 __FBSDID("$FreeBSD$");
76 #include "opt_kstack_pages.h"
77 #include "opt_kstack_max_pages.h"
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/limits.h>
83 #include <sys/kernel.h>
84 #include <sys/eventhandler.h>
86 #include <sys/mutex.h>
88 #include <sys/kthread.h>
90 #include <sys/mount.h>
91 #include <sys/racct.h>
92 #include <sys/resourcevar.h>
93 #include <sys/refcount.h>
94 #include <sys/sched.h>
96 #include <sys/signalvar.h>
99 #include <sys/vnode.h>
100 #include <sys/vmmeter.h>
101 #include <sys/rwlock.h>
103 #include <sys/sysctl.h>
106 #include <vm/vm_param.h>
107 #include <vm/vm_object.h>
108 #include <vm/vm_page.h>
109 #include <vm/vm_map.h>
110 #include <vm/vm_pageout.h>
111 #include <vm/vm_pager.h>
112 #include <vm/vm_phys.h>
113 #include <vm/swap_pager.h>
114 #include <vm/vm_extern.h>
117 /* the kernel process "vm_daemon" */
118 static void vm_daemon(void);
119 static struct proc *vmproc;
121 static struct kproc_desc vm_kp = {
126 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
128 static int vm_swap_enabled = 1;
129 static int vm_swap_idle_enabled = 0;
131 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW,
133 "Enable entire process swapout");
134 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW,
135 &vm_swap_idle_enabled, 0,
136 "Allow swapout on idle criteria");
139 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
141 static int swap_idle_threshold1 = 2;
142 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
143 &swap_idle_threshold1, 0,
144 "Guaranteed swapped in time for a process");
147 * Swap_idle_threshold2 is the time that a process can be idle before
148 * it will be swapped out, if idle swapping is enabled.
150 static int swap_idle_threshold2 = 10;
151 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
152 &swap_idle_threshold2, 0,
153 "Time before a process will be swapped out");
155 static int vm_pageout_req_swapout; /* XXX */
156 static int vm_daemon_needed;
157 static struct mtx vm_daemon_mtx;
158 /* Allow for use by vm_pageout before vm_daemon is initialized. */
159 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
161 static int swapped_cnt;
162 static int swap_inprogress; /* Pending swap-ins done outside swapper. */
163 static int last_swapin;
165 static void swapclear(struct proc *);
166 static int swapout(struct proc *);
167 static void vm_swapout_map_deactivate_pages(vm_map_t, long);
168 static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long);
169 static void swapout_procs(int action);
170 static void vm_req_vmdaemon(int req);
171 static void vm_thread_swapout(struct thread *td);
174 * vm_swapout_object_deactivate_pages
176 * Deactivate enough pages to satisfy the inactive target
179 * The object and map must be locked.
182 vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
185 vm_object_t backing_object, object;
187 int act_delta, remove_mode;
189 VM_OBJECT_ASSERT_LOCKED(first_object);
190 if ((first_object->flags & OBJ_FICTITIOUS) != 0)
192 for (object = first_object;; object = backing_object) {
193 if (pmap_resident_count(pmap) <= desired)
195 VM_OBJECT_ASSERT_LOCKED(object);
196 if ((object->flags & OBJ_UNMANAGED) != 0 ||
197 REFCOUNT_COUNT(object->paging_in_progress) > 0)
201 if (object->shadow_count > 1)
204 * Scan the object's entire memory queue.
206 TAILQ_FOREACH(p, &object->memq, listq) {
207 if (pmap_resident_count(pmap) <= desired)
211 if (vm_page_tryxbusy(p) == 0)
213 VM_CNT_INC(v_pdpages);
216 * The page may acquire a wiring after this check.
217 * The page daemon handles wired pages, so there is
218 * no harm done if a wiring appears while we are
219 * attempting to deactivate the page.
221 if (vm_page_wired(p) || !pmap_page_exists_quick(pmap, p)) {
225 act_delta = pmap_ts_referenced(p);
227 if ((p->a.flags & PGA_REFERENCED) != 0) {
230 vm_page_aflag_clear(p, PGA_REFERENCED);
232 if (!vm_page_active(p) && act_delta != 0) {
234 p->a.act_count += act_delta;
235 } else if (vm_page_active(p)) {
237 * The page daemon does not requeue pages
238 * after modifying their activation count.
240 if (act_delta == 0) {
241 p->a.act_count -= min(p->a.act_count,
243 if (!remove_mode && p->a.act_count == 0) {
244 (void)vm_page_try_remove_all(p);
245 vm_page_deactivate(p);
249 if (p->a.act_count < ACT_MAX -
251 p->a.act_count += ACT_ADVANCE;
253 } else if (vm_page_inactive(p))
254 (void)vm_page_try_remove_all(p);
258 if ((backing_object = object->backing_object) == NULL)
260 VM_OBJECT_RLOCK(backing_object);
261 if (object != first_object)
262 VM_OBJECT_RUNLOCK(object);
265 if (object != first_object)
266 VM_OBJECT_RUNLOCK(object);
270 * deactivate some number of pages in a map, try to do it fairly, but
271 * that is really hard to do.
274 vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
277 vm_object_t obj, bigobj;
280 if (!vm_map_trylock_read(map))
287 * first, search out the biggest object, and try to free pages from
290 VM_MAP_ENTRY_FOREACH(tmpe, map) {
291 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
292 obj = tmpe->object.vm_object;
293 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
294 if (obj->shadow_count <= 1 &&
296 bigobj->resident_page_count <
297 obj->resident_page_count)) {
299 VM_OBJECT_RUNLOCK(bigobj);
302 VM_OBJECT_RUNLOCK(obj);
305 if (tmpe->wired_count > 0)
306 nothingwired = FALSE;
309 if (bigobj != NULL) {
310 vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired);
311 VM_OBJECT_RUNLOCK(bigobj);
314 * Next, hunt around for other pages to deactivate. We actually
315 * do this search sort of wrong -- .text first is not the best idea.
317 VM_MAP_ENTRY_FOREACH(tmpe, map) {
318 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
320 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
321 obj = tmpe->object.vm_object;
323 VM_OBJECT_RLOCK(obj);
324 vm_swapout_object_deactivate_pages(map->pmap,
326 VM_OBJECT_RUNLOCK(obj);
332 * Remove all mappings if a process is swapped out, this will free page
335 if (desired == 0 && nothingwired) {
336 pmap_remove(vm_map_pmap(map), vm_map_min(map),
340 vm_map_unlock_read(map);
346 #define VM_SWAP_NORMAL 1
347 #define VM_SWAP_IDLE 2
354 vm_req_vmdaemon(VM_SWAP_NORMAL);
358 * Idle process swapout -- run once per second when pagedaemons are
362 vm_swapout_run_idle(void)
366 if (!vm_swap_idle_enabled || time_second == lsec)
368 vm_req_vmdaemon(VM_SWAP_IDLE);
373 vm_req_vmdaemon(int req)
375 static int lastrun = 0;
377 mtx_lock(&vm_daemon_mtx);
378 vm_pageout_req_swapout |= req;
379 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
380 wakeup(&vm_daemon_needed);
383 mtx_unlock(&vm_daemon_mtx);
389 struct rlimit rsslim;
393 int breakout, swapout_flags, tryagain, attempts;
395 uint64_t rsize, ravailable;
399 mtx_lock(&vm_daemon_mtx);
400 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
402 racct_enable ? hz : 0
407 swapout_flags = vm_pageout_req_swapout;
408 vm_pageout_req_swapout = 0;
409 mtx_unlock(&vm_daemon_mtx);
410 if (swapout_flags != 0) {
412 * Drain the per-CPU page queue batches as a deadlock
415 if ((swapout_flags & VM_SWAP_NORMAL) != 0)
416 vm_page_pqbatch_drain();
417 swapout_procs(swapout_flags);
421 * scan the processes for exceeding their rlimits or if
422 * process is swapped out -- deactivate pages
428 sx_slock(&allproc_lock);
429 FOREACH_PROC_IN_SYSTEM(p) {
430 vm_pindex_t limit, size;
433 * if this is a system process or if we have already
434 * looked at this process, skip it.
437 if (p->p_state != PRS_NORMAL ||
438 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
443 * if the process is in a non-running type state,
447 FOREACH_THREAD_IN_PROC(p, td) {
449 if (!TD_ON_RUNQ(td) &&
450 !TD_IS_RUNNING(td) &&
451 !TD_IS_SLEEPING(td) &&
452 !TD_IS_SUSPENDED(td)) {
466 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
468 qmin(rsslim.rlim_cur, rsslim.rlim_max));
471 * let processes that are swapped out really be
472 * swapped out set the limit to nothing (will force a
475 if ((p->p_flag & P_INMEM) == 0)
477 vm = vmspace_acquire_ref(p);
484 sx_sunlock(&allproc_lock);
486 size = vmspace_resident_count(vm);
488 vm_swapout_map_deactivate_pages(
490 size = vmspace_resident_count(vm);
494 rsize = IDX_TO_OFF(size);
496 if (p->p_state == PRS_NORMAL)
497 racct_set(p, RACCT_RSS, rsize);
498 ravailable = racct_get_available(p, RACCT_RSS);
500 if (rsize > ravailable) {
502 * Don't be overly aggressive; this
503 * might be an innocent process,
504 * and the limit could've been exceeded
505 * by some memory hog. Don't try
506 * to deactivate more than 1/4th
507 * of process' resident set size.
510 if (ravailable < rsize -
516 vm_swapout_map_deactivate_pages(
518 OFF_TO_IDX(ravailable));
519 /* Update RSS usage after paging out. */
520 size = vmspace_resident_count(vm);
521 rsize = IDX_TO_OFF(size);
523 if (p->p_state == PRS_NORMAL)
524 racct_set(p, RACCT_RSS, rsize);
526 if (rsize > ravailable)
532 sx_slock(&allproc_lock);
535 sx_sunlock(&allproc_lock);
536 if (tryagain != 0 && attempts <= 10) {
544 * Allow a thread's kernel stack to be paged out.
547 vm_thread_swapout(struct thread *td)
553 cpu_thread_swapout(td);
554 pages = td->td_kstack_pages;
555 ksobj = td->td_kstack_obj;
556 pmap_qremove(td->td_kstack, pages);
557 VM_OBJECT_WLOCK(ksobj);
558 for (i = 0; i < pages; i++) {
559 m = vm_page_lookup(ksobj, i);
561 panic("vm_thread_swapout: kstack already missing?");
563 vm_page_unwire(m, PQ_LAUNDRY);
565 VM_OBJECT_WUNLOCK(ksobj);
569 * Bring the kernel stack for a specified thread back in.
572 vm_thread_swapin(struct thread *td, int oom_alloc)
575 vm_page_t ma[KSTACK_MAX_PAGES];
576 int a, count, i, j, pages, rv;
578 pages = td->td_kstack_pages;
579 ksobj = td->td_kstack_obj;
580 VM_OBJECT_WLOCK(ksobj);
581 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma,
583 for (i = 0; i < pages;) {
584 vm_page_assert_xbusied(ma[i]);
585 if (vm_page_all_valid(ma[i])) {
586 vm_page_xunbusy(ma[i]);
590 vm_object_pip_add(ksobj, 1);
591 for (j = i + 1; j < pages; j++)
592 if (vm_page_all_valid(ma[j]))
594 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
595 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
596 count = min(a + 1, j - i);
597 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
598 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
599 __func__, td->td_proc->p_pid));
600 vm_object_pip_wakeup(ksobj);
601 for (j = i; j < i + count; j++)
602 vm_page_xunbusy(ma[j]);
605 VM_OBJECT_WUNLOCK(ksobj);
606 pmap_qenter(td->td_kstack, ma, pages);
607 cpu_thread_swapin(td);
611 faultin(struct proc *p)
616 PROC_LOCK_ASSERT(p, MA_OWNED);
619 * If another process is swapping in this process,
620 * just wait until it finishes.
622 if (p->p_flag & P_SWAPPINGIN) {
623 while (p->p_flag & P_SWAPPINGIN)
624 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
628 if ((p->p_flag & P_INMEM) == 0) {
629 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM :
633 * Don't let another thread swap process p out while we are
634 * busy swapping it in.
637 p->p_flag |= P_SWAPPINGIN;
639 sx_xlock(&allproc_lock);
640 MPASS(swapped_cnt > 0);
642 if (curthread != &thread0)
644 sx_xunlock(&allproc_lock);
647 * We hold no lock here because the list of threads
648 * can not change while all threads in the process are
651 FOREACH_THREAD_IN_PROC(p, td)
652 vm_thread_swapin(td, oom_alloc);
654 if (curthread != &thread0) {
655 sx_xlock(&allproc_lock);
656 MPASS(swap_inprogress > 0);
659 sx_xunlock(&allproc_lock);
665 /* Allow other threads to swap p out now. */
672 * This swapin algorithm attempts to swap-in processes only if there
673 * is enough space for them. Of course, if a process waits for a long
674 * time, it will be swapped in anyway.
678 swapper_selector(bool wkilled_only)
680 struct proc *p, *res;
682 int ppri, pri, slptime, swtime;
684 sx_assert(&allproc_lock, SA_SLOCKED);
685 if (swapped_cnt == 0)
689 FOREACH_PROC_IN_SYSTEM(p) {
691 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT |
692 P_SWAPPINGIN | P_INMEM)) != 0) {
696 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) {
698 * A swapped-out process might have mapped a
699 * large portion of the system's pages as
700 * anonymous memory. There is no other way to
701 * release the memory other than to kill the
702 * process, for which we need to swap it in.
710 swtime = (ticks - p->p_swtick) / hz;
711 FOREACH_THREAD_IN_PROC(p, td) {
713 * An otherwise runnable thread of a process
714 * swapped out has only the TDI_SWAPPED bit set.
717 if (td->td_inhibitors == TDI_SWAPPED) {
718 slptime = (ticks - td->td_slptick) / hz;
719 pri = swtime + slptime;
720 if ((td->td_flags & TDF_SWAPINREQ) == 0)
721 pri -= p->p_nice * 8;
723 * if this thread is higher priority
724 * and there is enough space, then select
725 * this process instead of the previous
743 #define SWAPIN_INTERVAL (MAXSLP * hz / 2)
746 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2
747 * interval, assuming that there is:
748 * - at least one domain that is not suffering from a shortage of free memory;
749 * - no parallel swap-ins;
750 * - no other swap-ins in the current SWAPIN_INTERVAL.
753 swapper_wkilled_only(void)
756 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
757 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
766 sx_slock(&allproc_lock);
767 p = swapper_selector(swapper_wkilled_only());
768 sx_sunlock(&allproc_lock);
771 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL);
773 PROC_LOCK_ASSERT(p, MA_OWNED);
776 * Another process may be bringing or may have
777 * already brought this process in while we
778 * traverse all threads. Or, this process may
779 * have exited or even being swapped out
782 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM |
783 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) {
792 * First, if any processes have been sleeping or stopped for at least
793 * "swap_idle_threshold1" seconds, they are swapped out. If, however,
794 * no such processes exist, then the longest-sleeping or stopped
795 * process is swapped out. Finally, and only as a last resort, if
796 * there are no sleeping or stopped processes, the longest-resident
797 * process is swapped out.
800 swapout_procs(int action)
805 bool didswap, doswap;
807 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
810 sx_slock(&allproc_lock);
811 FOREACH_PROC_IN_SYSTEM(p) {
813 * Filter out not yet fully constructed processes. Do
814 * not swap out held processes. Avoid processes which
815 * are system, exiting, execing, traced, already swapped
816 * out or are in the process of being swapped in or out.
819 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
820 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
821 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
828 * Further consideration of this process for swap out
829 * requires iterating over its threads. We release
830 * allproc_lock here so that process creation and
831 * destruction are not blocked while we iterate.
833 * To later reacquire allproc_lock and resume
834 * iteration over the allproc list, we will first have
835 * to release the lock on the process. We place a
836 * hold on the process so that it remains in the
837 * allproc list while it is unlocked.
840 sx_sunlock(&allproc_lock);
843 * Do not swapout a realtime process.
844 * Guarantee swap_idle_threshold1 time in memory.
845 * If the system is under memory stress, or if we are
846 * swapping idle processes >= swap_idle_threshold2,
847 * then swap the process out.
850 FOREACH_THREAD_IN_PROC(p, td) {
852 slptime = (ticks - td->td_slptick) / hz;
853 if (PRI_IS_REALTIME(td->td_pri_class) ||
854 slptime < swap_idle_threshold1 ||
855 !thread_safetoswapout(td) ||
856 ((action & VM_SWAP_NORMAL) == 0 &&
857 slptime < swap_idle_threshold2))
863 if (doswap && swapout(p) == 0)
868 sx_xlock(&allproc_lock);
870 sx_downgrade(&allproc_lock);
872 sx_slock(&allproc_lock);
875 sx_sunlock(&allproc_lock);
878 * If we swapped something out, and another process needed memory,
879 * then wakeup the sched process.
886 swapclear(struct proc *p)
890 PROC_LOCK_ASSERT(p, MA_OWNED);
892 FOREACH_THREAD_IN_PROC(p, td) {
894 td->td_flags |= TDF_INMEM;
895 td->td_flags &= ~TDF_SWAPINREQ;
898 if (setrunnable(td)) {
901 * XXX: We just cleared TDI_SWAPPED
902 * above and set TDF_INMEM, so this
903 * should never happen.
905 panic("not waking up swapper");
910 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
911 p->p_flag |= P_INMEM;
915 swapout(struct proc *p)
919 PROC_LOCK_ASSERT(p, MA_OWNED);
922 * The states of this process and its threads may have changed
923 * by now. Assuming that there is only one pageout daemon thread,
924 * this process should still be in memory.
926 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
927 P_INMEM, ("swapout: lost a swapout race?"));
930 * Remember the resident count.
932 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
935 * Check and mark all threads before we proceed.
937 p->p_flag &= ~P_INMEM;
938 p->p_flag |= P_SWAPPINGOUT;
939 FOREACH_THREAD_IN_PROC(p, td) {
941 if (!thread_safetoswapout(td)) {
946 td->td_flags &= ~TDF_INMEM;
950 td = FIRST_THREAD_IN_PROC(p);
951 ++td->td_ru.ru_nswap;
955 * This list is stable because all threads are now prevented from
956 * running. The list is only modified in the context of a running
957 * thread in this process.
959 FOREACH_THREAD_IN_PROC(p, td)
960 vm_thread_swapout(td);
963 p->p_flag &= ~P_SWAPPINGOUT;