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(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_page(pmap_t pmap, vm_page_t m, bool unmap)
178 if (vm_page_tryxbusy(m) == 0)
180 VM_CNT_INC(v_pdpages);
183 * The page may acquire a wiring after this check.
184 * The page daemon handles wired pages, so there is
185 * no harm done if a wiring appears while we are
186 * attempting to deactivate the page.
188 if (vm_page_wired(m) || !pmap_page_exists_quick(pmap, m)) {
192 act_delta = pmap_ts_referenced(m);
194 if ((m->a.flags & PGA_REFERENCED) != 0) {
197 vm_page_aflag_clear(m, PGA_REFERENCED);
199 if (!vm_page_active(m) && act_delta != 0) {
201 m->a.act_count += act_delta;
202 } else if (vm_page_active(m)) {
204 * The page daemon does not requeue pages
205 * after modifying their activation count.
207 if (act_delta == 0) {
208 m->a.act_count -= min(m->a.act_count, ACT_DECLINE);
209 if (unmap && m->a.act_count == 0) {
210 (void)vm_page_try_remove_all(m);
211 vm_page_deactivate(m);
215 if (m->a.act_count < ACT_MAX - ACT_ADVANCE)
216 m->a.act_count += ACT_ADVANCE;
218 } else if (vm_page_inactive(m))
219 (void)vm_page_try_remove_all(m);
225 * vm_swapout_object_deactivate
227 * Deactivate enough pages to satisfy the inactive target
230 * The object and map must be locked.
233 vm_swapout_object_deactivate(pmap_t pmap, vm_object_t first_object,
236 vm_object_t backing_object, object;
240 VM_OBJECT_ASSERT_LOCKED(first_object);
241 if ((first_object->flags & OBJ_FICTITIOUS) != 0)
243 for (object = first_object;; object = backing_object) {
244 if (pmap_resident_count(pmap) <= desired)
246 VM_OBJECT_ASSERT_LOCKED(object);
247 if ((object->flags & OBJ_UNMANAGED) != 0 ||
248 REFCOUNT_COUNT(object->paging_in_progress) > 0)
252 if (object->shadow_count > 1)
256 * Scan the object's entire memory queue.
258 TAILQ_FOREACH(m, &object->memq, listq) {
259 if (pmap_resident_count(pmap) <= desired)
263 vm_swapout_object_deactivate_page(pmap, m, unmap);
265 if ((backing_object = object->backing_object) == NULL)
267 VM_OBJECT_RLOCK(backing_object);
268 if (object != first_object)
269 VM_OBJECT_RUNLOCK(object);
272 if (object != first_object)
273 VM_OBJECT_RUNLOCK(object);
277 * deactivate some number of pages in a map, try to do it fairly, but
278 * that is really hard to do.
281 vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
284 vm_object_t obj, bigobj;
287 if (!vm_map_trylock_read(map))
294 * first, search out the biggest object, and try to free pages from
297 VM_MAP_ENTRY_FOREACH(tmpe, map) {
298 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
299 obj = tmpe->object.vm_object;
300 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
301 if (obj->shadow_count <= 1 &&
303 bigobj->resident_page_count <
304 obj->resident_page_count)) {
306 VM_OBJECT_RUNLOCK(bigobj);
309 VM_OBJECT_RUNLOCK(obj);
312 if (tmpe->wired_count > 0)
313 nothingwired = FALSE;
316 if (bigobj != NULL) {
317 vm_swapout_object_deactivate(map->pmap, bigobj, desired);
318 VM_OBJECT_RUNLOCK(bigobj);
321 * Next, hunt around for other pages to deactivate. We actually
322 * do this search sort of wrong -- .text first is not the best idea.
324 VM_MAP_ENTRY_FOREACH(tmpe, map) {
325 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
327 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
328 obj = tmpe->object.vm_object;
330 VM_OBJECT_RLOCK(obj);
331 vm_swapout_object_deactivate(map->pmap, obj,
333 VM_OBJECT_RUNLOCK(obj);
339 * Remove all mappings if a process is swapped out, this will free page
342 if (desired == 0 && nothingwired) {
343 pmap_remove(vm_map_pmap(map), vm_map_min(map),
347 vm_map_unlock_read(map);
353 #define VM_SWAP_NORMAL 1
354 #define VM_SWAP_IDLE 2
361 vm_req_vmdaemon(VM_SWAP_NORMAL);
365 * Idle process swapout -- run once per second when pagedaemons are
369 vm_swapout_run_idle(void)
373 if (!vm_swap_idle_enabled || time_second == lsec)
375 vm_req_vmdaemon(VM_SWAP_IDLE);
380 vm_req_vmdaemon(int req)
382 static int lastrun = 0;
384 mtx_lock(&vm_daemon_mtx);
385 vm_pageout_req_swapout |= req;
386 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
387 wakeup(&vm_daemon_needed);
390 mtx_unlock(&vm_daemon_mtx);
396 struct rlimit rsslim;
400 int breakout, swapout_flags, tryagain, attempts;
402 uint64_t rsize, ravailable;
406 mtx_lock(&vm_daemon_mtx);
407 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
409 racct_enable ? hz : 0
414 swapout_flags = vm_pageout_req_swapout;
415 vm_pageout_req_swapout = 0;
416 mtx_unlock(&vm_daemon_mtx);
417 if (swapout_flags != 0) {
419 * Drain the per-CPU page queue batches as a deadlock
422 if ((swapout_flags & VM_SWAP_NORMAL) != 0)
423 vm_page_pqbatch_drain();
424 swapout_procs(swapout_flags);
428 * scan the processes for exceeding their rlimits or if
429 * process is swapped out -- deactivate pages
435 sx_slock(&allproc_lock);
436 FOREACH_PROC_IN_SYSTEM(p) {
437 vm_pindex_t limit, size;
440 * if this is a system process or if we have already
441 * looked at this process, skip it.
444 if (p->p_state != PRS_NORMAL ||
445 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
450 * if the process is in a non-running type state,
454 FOREACH_THREAD_IN_PROC(p, td) {
456 if (!TD_ON_RUNQ(td) &&
457 !TD_IS_RUNNING(td) &&
458 !TD_IS_SLEEPING(td) &&
459 !TD_IS_SUSPENDED(td)) {
473 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
475 qmin(rsslim.rlim_cur, rsslim.rlim_max));
478 * let processes that are swapped out really be
479 * swapped out set the limit to nothing (will force a
482 if ((p->p_flag & P_INMEM) == 0)
484 vm = vmspace_acquire_ref(p);
491 sx_sunlock(&allproc_lock);
493 size = vmspace_resident_count(vm);
495 vm_swapout_map_deactivate_pages(
497 size = vmspace_resident_count(vm);
501 rsize = IDX_TO_OFF(size);
503 if (p->p_state == PRS_NORMAL)
504 racct_set(p, RACCT_RSS, rsize);
505 ravailable = racct_get_available(p, RACCT_RSS);
507 if (rsize > ravailable) {
509 * Don't be overly aggressive; this
510 * might be an innocent process,
511 * and the limit could've been exceeded
512 * by some memory hog. Don't try
513 * to deactivate more than 1/4th
514 * of process' resident set size.
517 if (ravailable < rsize -
523 vm_swapout_map_deactivate_pages(
525 OFF_TO_IDX(ravailable));
526 /* Update RSS usage after paging out. */
527 size = vmspace_resident_count(vm);
528 rsize = IDX_TO_OFF(size);
530 if (p->p_state == PRS_NORMAL)
531 racct_set(p, RACCT_RSS, rsize);
533 if (rsize > ravailable)
539 sx_slock(&allproc_lock);
542 sx_sunlock(&allproc_lock);
543 if (tryagain != 0 && attempts <= 10) {
551 * Allow a thread's kernel stack to be paged out.
554 vm_thread_swapout(struct thread *td)
560 cpu_thread_swapout(td);
561 pages = td->td_kstack_pages;
562 ksobj = td->td_kstack_obj;
563 pmap_qremove(td->td_kstack, pages);
564 VM_OBJECT_WLOCK(ksobj);
565 for (i = 0; i < pages; i++) {
566 m = vm_page_lookup(ksobj, i);
568 panic("vm_thread_swapout: kstack already missing?");
570 vm_page_unwire(m, PQ_LAUNDRY);
572 VM_OBJECT_WUNLOCK(ksobj);
576 * Bring the kernel stack for a specified thread back in.
579 vm_thread_swapin(struct thread *td, int oom_alloc)
582 vm_page_t ma[KSTACK_MAX_PAGES];
583 int a, count, i, j, pages, rv;
585 pages = td->td_kstack_pages;
586 ksobj = td->td_kstack_obj;
587 VM_OBJECT_WLOCK(ksobj);
588 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma,
590 for (i = 0; i < pages;) {
591 vm_page_assert_xbusied(ma[i]);
592 if (vm_page_all_valid(ma[i])) {
593 vm_page_xunbusy(ma[i]);
597 vm_object_pip_add(ksobj, 1);
598 for (j = i + 1; j < pages; j++)
599 if (vm_page_all_valid(ma[j]))
601 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
602 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
603 count = min(a + 1, j - i);
604 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
605 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
606 __func__, td->td_proc->p_pid));
607 vm_object_pip_wakeup(ksobj);
608 for (j = i; j < i + count; j++)
609 vm_page_xunbusy(ma[j]);
612 VM_OBJECT_WUNLOCK(ksobj);
613 pmap_qenter(td->td_kstack, ma, pages);
614 cpu_thread_swapin(td);
618 faultin(struct proc *p)
623 PROC_LOCK_ASSERT(p, MA_OWNED);
626 * If another process is swapping in this process,
627 * just wait until it finishes.
629 if (p->p_flag & P_SWAPPINGIN) {
630 while (p->p_flag & P_SWAPPINGIN)
631 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
635 if ((p->p_flag & P_INMEM) == 0) {
636 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM :
640 * Don't let another thread swap process p out while we are
641 * busy swapping it in.
644 p->p_flag |= P_SWAPPINGIN;
646 sx_xlock(&allproc_lock);
647 MPASS(swapped_cnt > 0);
649 if (curthread != &thread0)
651 sx_xunlock(&allproc_lock);
654 * We hold no lock here because the list of threads
655 * can not change while all threads in the process are
658 FOREACH_THREAD_IN_PROC(p, td)
659 vm_thread_swapin(td, oom_alloc);
661 if (curthread != &thread0) {
662 sx_xlock(&allproc_lock);
663 MPASS(swap_inprogress > 0);
666 sx_xunlock(&allproc_lock);
672 /* Allow other threads to swap p out now. */
679 * This swapin algorithm attempts to swap-in processes only if there
680 * is enough space for them. Of course, if a process waits for a long
681 * time, it will be swapped in anyway.
685 swapper_selector(bool wkilled_only)
687 struct proc *p, *res;
689 int ppri, pri, slptime, swtime;
691 sx_assert(&allproc_lock, SA_SLOCKED);
692 if (swapped_cnt == 0)
696 FOREACH_PROC_IN_SYSTEM(p) {
698 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT |
699 P_SWAPPINGIN | P_INMEM)) != 0) {
703 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) {
705 * A swapped-out process might have mapped a
706 * large portion of the system's pages as
707 * anonymous memory. There is no other way to
708 * release the memory other than to kill the
709 * process, for which we need to swap it in.
717 swtime = (ticks - p->p_swtick) / hz;
718 FOREACH_THREAD_IN_PROC(p, td) {
720 * An otherwise runnable thread of a process
721 * swapped out has only the TDI_SWAPPED bit set.
724 if (td->td_inhibitors == TDI_SWAPPED) {
725 slptime = (ticks - td->td_slptick) / hz;
726 pri = swtime + slptime;
727 if ((td->td_flags & TDF_SWAPINREQ) == 0)
728 pri -= p->p_nice * 8;
730 * if this thread is higher priority
731 * and there is enough space, then select
732 * this process instead of the previous
750 #define SWAPIN_INTERVAL (MAXSLP * hz / 2)
753 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2
754 * interval, assuming that there is:
755 * - at least one domain that is not suffering from a shortage of free memory;
756 * - no parallel swap-ins;
757 * - no other swap-ins in the current SWAPIN_INTERVAL.
760 swapper_wkilled_only(void)
763 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
764 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
773 sx_slock(&allproc_lock);
774 p = swapper_selector(swapper_wkilled_only());
775 sx_sunlock(&allproc_lock);
778 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL);
780 PROC_LOCK_ASSERT(p, MA_OWNED);
783 * Another process may be bringing or may have
784 * already brought this process in while we
785 * traverse all threads. Or, this process may
786 * have exited or even being swapped out
789 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM |
790 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) {
799 * First, if any processes have been sleeping or stopped for at least
800 * "swap_idle_threshold1" seconds, they are swapped out. If, however,
801 * no such processes exist, then the longest-sleeping or stopped
802 * process is swapped out. Finally, and only as a last resort, if
803 * there are no sleeping or stopped processes, the longest-resident
804 * process is swapped out.
807 swapout_procs(int action)
812 bool didswap, doswap;
814 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
817 sx_slock(&allproc_lock);
818 FOREACH_PROC_IN_SYSTEM(p) {
820 * Filter out not yet fully constructed processes. Do
821 * not swap out held processes. Avoid processes which
822 * are system, exiting, execing, traced, already swapped
823 * out or are in the process of being swapped in or out.
826 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
827 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
828 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
835 * Further consideration of this process for swap out
836 * requires iterating over its threads. We release
837 * allproc_lock here so that process creation and
838 * destruction are not blocked while we iterate.
840 * To later reacquire allproc_lock and resume
841 * iteration over the allproc list, we will first have
842 * to release the lock on the process. We place a
843 * hold on the process so that it remains in the
844 * allproc list while it is unlocked.
847 sx_sunlock(&allproc_lock);
850 * Do not swapout a realtime process.
851 * Guarantee swap_idle_threshold1 time in memory.
852 * If the system is under memory stress, or if we are
853 * swapping idle processes >= swap_idle_threshold2,
854 * then swap the process out.
857 FOREACH_THREAD_IN_PROC(p, td) {
859 slptime = (ticks - td->td_slptick) / hz;
860 if (PRI_IS_REALTIME(td->td_pri_class) ||
861 slptime < swap_idle_threshold1 ||
862 !thread_safetoswapout(td) ||
863 ((action & VM_SWAP_NORMAL) == 0 &&
864 slptime < swap_idle_threshold2))
870 if (doswap && swapout(p) == 0)
875 sx_xlock(&allproc_lock);
877 sx_downgrade(&allproc_lock);
879 sx_slock(&allproc_lock);
882 sx_sunlock(&allproc_lock);
885 * If we swapped something out, and another process needed memory,
886 * then wakeup the sched process.
893 swapclear(struct proc *p)
897 PROC_LOCK_ASSERT(p, MA_OWNED);
899 FOREACH_THREAD_IN_PROC(p, td) {
901 td->td_flags |= TDF_INMEM;
902 td->td_flags &= ~TDF_SWAPINREQ;
904 if (TD_CAN_RUN(td)) {
905 if (setrunnable(td, 0)) {
908 * XXX: We just cleared TDI_SWAPPED
909 * above and set TDF_INMEM, so this
910 * should never happen.
912 panic("not waking up swapper");
918 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
919 p->p_flag |= P_INMEM;
923 swapout(struct proc *p)
927 PROC_LOCK_ASSERT(p, MA_OWNED);
930 * The states of this process and its threads may have changed
931 * by now. Assuming that there is only one pageout daemon thread,
932 * this process should still be in memory.
934 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
935 P_INMEM, ("swapout: lost a swapout race?"));
938 * Remember the resident count.
940 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
943 * Check and mark all threads before we proceed.
945 p->p_flag &= ~P_INMEM;
946 p->p_flag |= P_SWAPPINGOUT;
947 FOREACH_THREAD_IN_PROC(p, td) {
949 if (!thread_safetoswapout(td)) {
954 td->td_flags &= ~TDF_INMEM;
958 td = FIRST_THREAD_IN_PROC(p);
959 ++td->td_ru.ru_nswap;
963 * This list is stable because all threads are now prevented from
964 * running. The list is only modified in the context of a running
965 * thread in this process.
967 FOREACH_THREAD_IN_PROC(p, td)
968 vm_thread_swapout(td);
971 p->p_flag &= ~P_SWAPPINGOUT;