1 /*- 2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991 Regents of the University of California. 5 * All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * Copyright (c) 2005 Yahoo! Technologies Norway AS 11 * All rights reserved. 12 * 13 * This code is derived from software contributed to Berkeley by 14 * The Mach Operating System project at Carnegie-Mellon University. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 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. 31 * 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 42 * SUCH DAMAGE. 43 * 44 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 45 * 46 * 47 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 48 * All rights reserved. 49 * 50 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 51 * 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. 57 * 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. 61 * 62 * Carnegie Mellon requests users of this software to return to 63 * 64 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 65 * School of Computer Science 66 * Carnegie Mellon University 67 * Pittsburgh PA 15213-3890 68 * 69 * any improvements or extensions that they make and grant Carnegie the 70 * rights to redistribute these changes. 71 */ 72 73 #include <sys/cdefs.h> 74 __FBSDID("$FreeBSD$"); 75 76 #include "opt_kstack_pages.h" 77 #include "opt_kstack_max_pages.h" 78 #include "opt_vm.h" 79 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> 85 #include <sys/lock.h> 86 #include <sys/mutex.h> 87 #include <sys/proc.h> 88 #include <sys/_kstack_cache.h> 89 #include <sys/kthread.h> 90 #include <sys/ktr.h> 91 #include <sys/mount.h> 92 #include <sys/racct.h> 93 #include <sys/resourcevar.h> 94 #include <sys/sched.h> 95 #include <sys/sdt.h> 96 #include <sys/signalvar.h> 97 #include <sys/smp.h> 98 #include <sys/time.h> 99 #include <sys/vnode.h> 100 #include <sys/vmmeter.h> 101 #include <sys/rwlock.h> 102 #include <sys/sx.h> 103 #include <sys/sysctl.h> 104 105 #include <vm/vm.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> 115 #include <vm/uma.h> 116 117 /* the kernel process "vm_daemon" */ 118 static void vm_daemon(void); 119 static struct proc *vmproc; 120 121 static struct kproc_desc vm_kp = { 122 "vmdaemon", 123 vm_daemon, 124 &vmproc 125 }; 126 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 127 128 static int vm_swap_enabled = 1; 129 static int vm_swap_idle_enabled = 0; 130 131 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, 132 &vm_swap_enabled, 0, 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"); 137 138 /* 139 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 140 */ 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"); 145 146 /* 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. 149 */ 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"); 154 155 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); 160 161 static int swapped_cnt; 162 163 static void swapclear(struct proc *); 164 static int swapout(struct proc *); 165 static void vm_swapout_map_deactivate_pages(vm_map_t, long); 166 static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long); 167 static void swapout_procs(int action); 168 static void vm_req_vmdaemon(int req); 169 static void vm_thread_swapout(struct thread *td); 170 171 /* 172 * vm_swapout_object_deactivate_pages 173 * 174 * Deactivate enough pages to satisfy the inactive target 175 * requirements. 176 * 177 * The object and map must be locked. 178 */ 179 static void 180 vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 181 long desired) 182 { 183 vm_object_t backing_object, object; 184 vm_page_t p; 185 int act_delta, remove_mode; 186 187 VM_OBJECT_ASSERT_LOCKED(first_object); 188 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 189 return; 190 for (object = first_object;; object = backing_object) { 191 if (pmap_resident_count(pmap) <= desired) 192 goto unlock_return; 193 VM_OBJECT_ASSERT_LOCKED(object); 194 if ((object->flags & OBJ_UNMANAGED) != 0 || 195 object->paging_in_progress != 0) 196 goto unlock_return; 197 198 remove_mode = 0; 199 if (object->shadow_count > 1) 200 remove_mode = 1; 201 /* 202 * Scan the object's entire memory queue. 203 */ 204 TAILQ_FOREACH(p, &object->memq, listq) { 205 if (pmap_resident_count(pmap) <= desired) 206 goto unlock_return; 207 if (should_yield()) 208 goto unlock_return; 209 if (vm_page_busied(p)) 210 continue; 211 VM_CNT_INC(v_pdpages); 212 vm_page_lock(p); 213 if (vm_page_held(p) || 214 !pmap_page_exists_quick(pmap, p)) { 215 vm_page_unlock(p); 216 continue; 217 } 218 act_delta = pmap_ts_referenced(p); 219 if ((p->aflags & PGA_REFERENCED) != 0) { 220 if (act_delta == 0) 221 act_delta = 1; 222 vm_page_aflag_clear(p, PGA_REFERENCED); 223 } 224 if (!vm_page_active(p) && act_delta != 0) { 225 vm_page_activate(p); 226 p->act_count += act_delta; 227 } else if (vm_page_active(p)) { 228 if (act_delta == 0) { 229 p->act_count -= min(p->act_count, 230 ACT_DECLINE); 231 if (!remove_mode && p->act_count == 0) { 232 pmap_remove_all(p); 233 vm_page_deactivate(p); 234 } else 235 vm_page_requeue(p); 236 } else { 237 vm_page_activate(p); 238 if (p->act_count < ACT_MAX - 239 ACT_ADVANCE) 240 p->act_count += ACT_ADVANCE; 241 vm_page_requeue(p); 242 } 243 } else if (vm_page_inactive(p)) 244 pmap_remove_all(p); 245 vm_page_unlock(p); 246 } 247 if ((backing_object = object->backing_object) == NULL) 248 goto unlock_return; 249 VM_OBJECT_RLOCK(backing_object); 250 if (object != first_object) 251 VM_OBJECT_RUNLOCK(object); 252 } 253 unlock_return: 254 if (object != first_object) 255 VM_OBJECT_RUNLOCK(object); 256 } 257 258 /* 259 * deactivate some number of pages in a map, try to do it fairly, but 260 * that is really hard to do. 261 */ 262 static void 263 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 264 { 265 vm_map_entry_t tmpe; 266 vm_object_t obj, bigobj; 267 int nothingwired; 268 269 if (!vm_map_trylock_read(map)) 270 return; 271 272 bigobj = NULL; 273 nothingwired = TRUE; 274 275 /* 276 * first, search out the biggest object, and try to free pages from 277 * that. 278 */ 279 tmpe = map->header.next; 280 while (tmpe != &map->header) { 281 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 282 obj = tmpe->object.vm_object; 283 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 284 if (obj->shadow_count <= 1 && 285 (bigobj == NULL || 286 bigobj->resident_page_count < 287 obj->resident_page_count)) { 288 if (bigobj != NULL) 289 VM_OBJECT_RUNLOCK(bigobj); 290 bigobj = obj; 291 } else 292 VM_OBJECT_RUNLOCK(obj); 293 } 294 } 295 if (tmpe->wired_count > 0) 296 nothingwired = FALSE; 297 tmpe = tmpe->next; 298 } 299 300 if (bigobj != NULL) { 301 vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired); 302 VM_OBJECT_RUNLOCK(bigobj); 303 } 304 /* 305 * Next, hunt around for other pages to deactivate. We actually 306 * do this search sort of wrong -- .text first is not the best idea. 307 */ 308 tmpe = map->header.next; 309 while (tmpe != &map->header) { 310 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 311 break; 312 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 313 obj = tmpe->object.vm_object; 314 if (obj != NULL) { 315 VM_OBJECT_RLOCK(obj); 316 vm_swapout_object_deactivate_pages(map->pmap, 317 obj, desired); 318 VM_OBJECT_RUNLOCK(obj); 319 } 320 } 321 tmpe = tmpe->next; 322 } 323 324 /* 325 * Remove all mappings if a process is swapped out, this will free page 326 * table pages. 327 */ 328 if (desired == 0 && nothingwired) { 329 pmap_remove(vm_map_pmap(map), vm_map_min(map), 330 vm_map_max(map)); 331 } 332 333 vm_map_unlock_read(map); 334 } 335 336 /* 337 * Swap out requests 338 */ 339 #define VM_SWAP_NORMAL 1 340 #define VM_SWAP_IDLE 2 341 342 void 343 vm_swapout_run(void) 344 { 345 346 if (vm_swap_enabled) 347 vm_req_vmdaemon(VM_SWAP_NORMAL); 348 } 349 350 /* 351 * Idle process swapout -- run once per second when pagedaemons are 352 * reclaiming pages. 353 */ 354 void 355 vm_swapout_run_idle(void) 356 { 357 static long lsec; 358 359 if (!vm_swap_idle_enabled || time_second == lsec) 360 return; 361 vm_req_vmdaemon(VM_SWAP_IDLE); 362 lsec = time_second; 363 } 364 365 static void 366 vm_req_vmdaemon(int req) 367 { 368 static int lastrun = 0; 369 370 mtx_lock(&vm_daemon_mtx); 371 vm_pageout_req_swapout |= req; 372 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 373 wakeup(&vm_daemon_needed); 374 lastrun = ticks; 375 } 376 mtx_unlock(&vm_daemon_mtx); 377 } 378 379 static void 380 vm_daemon(void) 381 { 382 struct rlimit rsslim; 383 struct proc *p; 384 struct thread *td; 385 struct vmspace *vm; 386 int breakout, swapout_flags, tryagain, attempts; 387 #ifdef RACCT 388 uint64_t rsize, ravailable; 389 #endif 390 391 while (TRUE) { 392 mtx_lock(&vm_daemon_mtx); 393 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 394 #ifdef RACCT 395 racct_enable ? hz : 0 396 #else 397 0 398 #endif 399 ); 400 swapout_flags = vm_pageout_req_swapout; 401 vm_pageout_req_swapout = 0; 402 mtx_unlock(&vm_daemon_mtx); 403 if (swapout_flags != 0) { 404 /* 405 * Drain the per-CPU page queue batches as a deadlock 406 * avoidance measure. 407 */ 408 if ((swapout_flags & VM_SWAP_NORMAL) != 0) 409 vm_page_drain_pqbatch(); 410 swapout_procs(swapout_flags); 411 } 412 413 /* 414 * scan the processes for exceeding their rlimits or if 415 * process is swapped out -- deactivate pages 416 */ 417 tryagain = 0; 418 attempts = 0; 419 again: 420 attempts++; 421 sx_slock(&allproc_lock); 422 FOREACH_PROC_IN_SYSTEM(p) { 423 vm_pindex_t limit, size; 424 425 /* 426 * if this is a system process or if we have already 427 * looked at this process, skip it. 428 */ 429 PROC_LOCK(p); 430 if (p->p_state != PRS_NORMAL || 431 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 432 PROC_UNLOCK(p); 433 continue; 434 } 435 /* 436 * if the process is in a non-running type state, 437 * don't touch it. 438 */ 439 breakout = 0; 440 FOREACH_THREAD_IN_PROC(p, td) { 441 thread_lock(td); 442 if (!TD_ON_RUNQ(td) && 443 !TD_IS_RUNNING(td) && 444 !TD_IS_SLEEPING(td) && 445 !TD_IS_SUSPENDED(td)) { 446 thread_unlock(td); 447 breakout = 1; 448 break; 449 } 450 thread_unlock(td); 451 } 452 if (breakout) { 453 PROC_UNLOCK(p); 454 continue; 455 } 456 /* 457 * get a limit 458 */ 459 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 460 limit = OFF_TO_IDX( 461 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 462 463 /* 464 * let processes that are swapped out really be 465 * swapped out set the limit to nothing (will force a 466 * swap-out.) 467 */ 468 if ((p->p_flag & P_INMEM) == 0) 469 limit = 0; /* XXX */ 470 vm = vmspace_acquire_ref(p); 471 _PHOLD_LITE(p); 472 PROC_UNLOCK(p); 473 if (vm == NULL) { 474 PRELE(p); 475 continue; 476 } 477 sx_sunlock(&allproc_lock); 478 479 size = vmspace_resident_count(vm); 480 if (size >= limit) { 481 vm_swapout_map_deactivate_pages( 482 &vm->vm_map, limit); 483 size = vmspace_resident_count(vm); 484 } 485 #ifdef RACCT 486 if (racct_enable) { 487 rsize = IDX_TO_OFF(size); 488 PROC_LOCK(p); 489 if (p->p_state == PRS_NORMAL) 490 racct_set(p, RACCT_RSS, rsize); 491 ravailable = racct_get_available(p, RACCT_RSS); 492 PROC_UNLOCK(p); 493 if (rsize > ravailable) { 494 /* 495 * Don't be overly aggressive; this 496 * might be an innocent process, 497 * and the limit could've been exceeded 498 * by some memory hog. Don't try 499 * to deactivate more than 1/4th 500 * of process' resident set size. 501 */ 502 if (attempts <= 8) { 503 if (ravailable < rsize - 504 (rsize / 4)) { 505 ravailable = rsize - 506 (rsize / 4); 507 } 508 } 509 vm_swapout_map_deactivate_pages( 510 &vm->vm_map, 511 OFF_TO_IDX(ravailable)); 512 /* Update RSS usage after paging out. */ 513 size = vmspace_resident_count(vm); 514 rsize = IDX_TO_OFF(size); 515 PROC_LOCK(p); 516 if (p->p_state == PRS_NORMAL) 517 racct_set(p, RACCT_RSS, rsize); 518 PROC_UNLOCK(p); 519 if (rsize > ravailable) 520 tryagain = 1; 521 } 522 } 523 #endif 524 vmspace_free(vm); 525 sx_slock(&allproc_lock); 526 PRELE(p); 527 } 528 sx_sunlock(&allproc_lock); 529 if (tryagain != 0 && attempts <= 10) { 530 maybe_yield(); 531 goto again; 532 } 533 } 534 } 535 536 /* 537 * Allow a thread's kernel stack to be paged out. 538 */ 539 static void 540 vm_thread_swapout(struct thread *td) 541 { 542 vm_object_t ksobj; 543 vm_page_t m; 544 int i, pages; 545 546 cpu_thread_swapout(td); 547 pages = td->td_kstack_pages; 548 ksobj = td->td_kstack_obj; 549 pmap_qremove(td->td_kstack, pages); 550 VM_OBJECT_WLOCK(ksobj); 551 for (i = 0; i < pages; i++) { 552 m = vm_page_lookup(ksobj, i); 553 if (m == NULL) 554 panic("vm_thread_swapout: kstack already missing?"); 555 vm_page_dirty(m); 556 vm_page_lock(m); 557 vm_page_unwire(m, PQ_LAUNDRY); 558 vm_page_unlock(m); 559 } 560 VM_OBJECT_WUNLOCK(ksobj); 561 } 562 563 /* 564 * Bring the kernel stack for a specified thread back in. 565 */ 566 static void 567 vm_thread_swapin(struct thread *td, int oom_alloc) 568 { 569 vm_object_t ksobj; 570 vm_page_t ma[KSTACK_MAX_PAGES]; 571 int a, count, i, j, pages, rv; 572 573 pages = td->td_kstack_pages; 574 ksobj = td->td_kstack_obj; 575 VM_OBJECT_WLOCK(ksobj); 576 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma, 577 pages); 578 for (i = 0; i < pages;) { 579 vm_page_assert_xbusied(ma[i]); 580 if (ma[i]->valid == VM_PAGE_BITS_ALL) { 581 vm_page_xunbusy(ma[i]); 582 i++; 583 continue; 584 } 585 vm_object_pip_add(ksobj, 1); 586 for (j = i + 1; j < pages; j++) 587 if (ma[j]->valid == VM_PAGE_BITS_ALL) 588 break; 589 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 590 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 591 count = min(a + 1, j - i); 592 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 593 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 594 __func__, td->td_proc->p_pid)); 595 vm_object_pip_wakeup(ksobj); 596 for (j = i; j < i + count; j++) 597 vm_page_xunbusy(ma[j]); 598 i += count; 599 } 600 VM_OBJECT_WUNLOCK(ksobj); 601 pmap_qenter(td->td_kstack, ma, pages); 602 cpu_thread_swapin(td); 603 } 604 605 void 606 faultin(struct proc *p) 607 { 608 struct thread *td; 609 int oom_alloc; 610 611 PROC_LOCK_ASSERT(p, MA_OWNED); 612 613 /* 614 * If another process is swapping in this process, 615 * just wait until it finishes. 616 */ 617 if (p->p_flag & P_SWAPPINGIN) { 618 while (p->p_flag & P_SWAPPINGIN) 619 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 620 return; 621 } 622 623 if ((p->p_flag & P_INMEM) == 0) { 624 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM : 625 VM_ALLOC_NORMAL; 626 627 /* 628 * Don't let another thread swap process p out while we are 629 * busy swapping it in. 630 */ 631 ++p->p_lock; 632 p->p_flag |= P_SWAPPINGIN; 633 PROC_UNLOCK(p); 634 sx_xlock(&allproc_lock); 635 MPASS(swapped_cnt > 0); 636 swapped_cnt--; 637 sx_xunlock(&allproc_lock); 638 639 /* 640 * We hold no lock here because the list of threads 641 * can not change while all threads in the process are 642 * swapped out. 643 */ 644 FOREACH_THREAD_IN_PROC(p, td) 645 vm_thread_swapin(td, oom_alloc); 646 647 PROC_LOCK(p); 648 swapclear(p); 649 p->p_swtick = ticks; 650 651 /* Allow other threads to swap p out now. */ 652 wakeup(&p->p_flag); 653 --p->p_lock; 654 } 655 } 656 657 /* 658 * This swapin algorithm attempts to swap-in processes only if there 659 * is enough space for them. Of course, if a process waits for a long 660 * time, it will be swapped in anyway. 661 */ 662 663 static struct proc * 664 swapper_selector(void) 665 { 666 struct proc *p, *res; 667 struct thread *td; 668 int min_flag, ppri, pri, slptime, swtime; 669 670 sx_assert(&allproc_lock, SA_SLOCKED); 671 if (swapped_cnt == 0) 672 return (NULL); 673 res = NULL; 674 ppri = INT_MIN; 675 min_flag = vm_page_count_min(); 676 FOREACH_PROC_IN_SYSTEM(p) { 677 PROC_LOCK(p); 678 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | 679 P_SWAPPINGIN | P_INMEM)) != 0) { 680 PROC_UNLOCK(p); 681 continue; 682 } 683 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) { 684 /* 685 * A swapped-out process might have mapped a 686 * large portion of the system's pages as 687 * anonymous memory. There is no other way to 688 * release the memory other than to kill the 689 * process, for which we need to swap it in. 690 */ 691 return (p); 692 } 693 if (min_flag) { 694 PROC_UNLOCK(p); 695 continue; 696 } 697 swtime = (ticks - p->p_swtick) / hz; 698 FOREACH_THREAD_IN_PROC(p, td) { 699 /* 700 * An otherwise runnable thread of a process 701 * swapped out has only the TDI_SWAPPED bit set. 702 */ 703 thread_lock(td); 704 if (td->td_inhibitors == TDI_SWAPPED) { 705 slptime = (ticks - td->td_slptick) / hz; 706 pri = swtime + slptime; 707 if ((td->td_flags & TDF_SWAPINREQ) == 0) 708 pri -= p->p_nice * 8; 709 /* 710 * if this thread is higher priority 711 * and there is enough space, then select 712 * this process instead of the previous 713 * selection. 714 */ 715 if (pri > ppri) { 716 res = p; 717 ppri = pri; 718 } 719 } 720 thread_unlock(td); 721 } 722 PROC_UNLOCK(p); 723 } 724 if (res != NULL) 725 PROC_LOCK(res); 726 return (res); 727 } 728 729 void 730 swapper(void) 731 { 732 struct proc *p; 733 734 for (;;) { 735 sx_slock(&allproc_lock); 736 p = swapper_selector(); 737 sx_sunlock(&allproc_lock); 738 739 if (p == NULL) { 740 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); 741 } else { 742 PROC_LOCK_ASSERT(p, MA_OWNED); 743 744 /* 745 * Another process may be bringing or may have 746 * already brought this process in while we 747 * traverse all threads. Or, this process may 748 * have exited or even being swapped out 749 * again. 750 */ 751 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM | 752 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) { 753 faultin(p); 754 } 755 PROC_UNLOCK(p); 756 } 757 } 758 } 759 760 /* 761 * First, if any processes have been sleeping or stopped for at least 762 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 763 * no such processes exist, then the longest-sleeping or stopped 764 * process is swapped out. Finally, and only as a last resort, if 765 * there are no sleeping or stopped processes, the longest-resident 766 * process is swapped out. 767 */ 768 static void 769 swapout_procs(int action) 770 { 771 struct proc *p; 772 struct thread *td; 773 int slptime; 774 bool didswap, doswap; 775 776 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); 777 778 didswap = false; 779 sx_slock(&allproc_lock); 780 FOREACH_PROC_IN_SYSTEM(p) { 781 /* 782 * Filter out not yet fully constructed processes. Do 783 * not swap out held processes. Avoid processes which 784 * are system, exiting, execing, traced, already swapped 785 * out or are in the process of being swapped in or out. 786 */ 787 PROC_LOCK(p); 788 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & 789 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | 790 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != 791 P_INMEM) { 792 PROC_UNLOCK(p); 793 continue; 794 } 795 796 /* 797 * Further consideration of this process for swap out 798 * requires iterating over its threads. We release 799 * allproc_lock here so that process creation and 800 * destruction are not blocked while we iterate. 801 * 802 * To later reacquire allproc_lock and resume 803 * iteration over the allproc list, we will first have 804 * to release the lock on the process. We place a 805 * hold on the process so that it remains in the 806 * allproc list while it is unlocked. 807 */ 808 _PHOLD_LITE(p); 809 sx_sunlock(&allproc_lock); 810 811 /* 812 * Do not swapout a realtime process. 813 * Guarantee swap_idle_threshold1 time in memory. 814 * If the system is under memory stress, or if we are 815 * swapping idle processes >= swap_idle_threshold2, 816 * then swap the process out. 817 */ 818 doswap = true; 819 FOREACH_THREAD_IN_PROC(p, td) { 820 thread_lock(td); 821 slptime = (ticks - td->td_slptick) / hz; 822 if (PRI_IS_REALTIME(td->td_pri_class) || 823 slptime < swap_idle_threshold1 || 824 !thread_safetoswapout(td) || 825 ((action & VM_SWAP_NORMAL) == 0 && 826 slptime < swap_idle_threshold2)) 827 doswap = false; 828 thread_unlock(td); 829 if (!doswap) 830 break; 831 } 832 if (doswap && swapout(p) == 0) 833 didswap = true; 834 835 PROC_UNLOCK(p); 836 if (didswap) { 837 sx_xlock(&allproc_lock); 838 swapped_cnt++; 839 sx_downgrade(&allproc_lock); 840 } else 841 sx_slock(&allproc_lock); 842 PRELE(p); 843 } 844 sx_sunlock(&allproc_lock); 845 846 /* 847 * If we swapped something out, and another process needed memory, 848 * then wakeup the sched process. 849 */ 850 if (didswap) 851 wakeup(&proc0); 852 } 853 854 static void 855 swapclear(struct proc *p) 856 { 857 struct thread *td; 858 859 PROC_LOCK_ASSERT(p, MA_OWNED); 860 861 FOREACH_THREAD_IN_PROC(p, td) { 862 thread_lock(td); 863 td->td_flags |= TDF_INMEM; 864 td->td_flags &= ~TDF_SWAPINREQ; 865 TD_CLR_SWAPPED(td); 866 if (TD_CAN_RUN(td)) 867 if (setrunnable(td)) { 868 #ifdef INVARIANTS 869 /* 870 * XXX: We just cleared TDI_SWAPPED 871 * above and set TDF_INMEM, so this 872 * should never happen. 873 */ 874 panic("not waking up swapper"); 875 #endif 876 } 877 thread_unlock(td); 878 } 879 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 880 p->p_flag |= P_INMEM; 881 } 882 883 static int 884 swapout(struct proc *p) 885 { 886 struct thread *td; 887 888 PROC_LOCK_ASSERT(p, MA_OWNED); 889 890 /* 891 * The states of this process and its threads may have changed 892 * by now. Assuming that there is only one pageout daemon thread, 893 * this process should still be in memory. 894 */ 895 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 896 P_INMEM, ("swapout: lost a swapout race?")); 897 898 /* 899 * Remember the resident count. 900 */ 901 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 902 903 /* 904 * Check and mark all threads before we proceed. 905 */ 906 p->p_flag &= ~P_INMEM; 907 p->p_flag |= P_SWAPPINGOUT; 908 FOREACH_THREAD_IN_PROC(p, td) { 909 thread_lock(td); 910 if (!thread_safetoswapout(td)) { 911 thread_unlock(td); 912 swapclear(p); 913 return (EBUSY); 914 } 915 td->td_flags &= ~TDF_INMEM; 916 TD_SET_SWAPPED(td); 917 thread_unlock(td); 918 } 919 td = FIRST_THREAD_IN_PROC(p); 920 ++td->td_ru.ru_nswap; 921 PROC_UNLOCK(p); 922 923 /* 924 * This list is stable because all threads are now prevented from 925 * running. The list is only modified in the context of a running 926 * thread in this process. 927 */ 928 FOREACH_THREAD_IN_PROC(p, td) 929 vm_thread_swapout(td); 930 931 PROC_LOCK(p); 932 p->p_flag &= ~P_SWAPPINGOUT; 933 p->p_swtick = ticks; 934 return (0); 935 } 936