Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/vm/vm_glue.c
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1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 33 * 34 * 35 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 36 * All rights reserved. 37 * 38 * Permission to use, copy, modify and distribute this software and 39 * its documentation is hereby granted, provided that both the copyright 40 * notice and this permission notice appear in all copies of the 41 * software, derivative works or modified versions, and any portions 42 * thereof, and that both notices appear in supporting documentation. 43 * 44 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 45 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 46 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 47 * 48 * Carnegie Mellon requests users of this software to return to 49 * 50 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 51 * School of Computer Science 52 * Carnegie Mellon University 53 * Pittsburgh PA 15213-3890 54 * 55 * any improvements or extensions that they make and grant Carnegie the 56 * rights to redistribute these changes. 57 */ 58 59 #include <sys/cdefs.h> 60 __FBSDID("$FreeBSD: releng/10.0/sys/vm/vm_glue.c 254649 2013-08-22 07:39:53Z kib $"); 61 62 #include "opt_vm.h" 63 #include "opt_kstack_pages.h" 64 #include "opt_kstack_max_pages.h" 65 66 #include <sys/param.h> 67 #include <sys/systm.h> 68 #include <sys/limits.h> 69 #include <sys/lock.h> 70 #include <sys/malloc.h> 71 #include <sys/mutex.h> 72 #include <sys/proc.h> 73 #include <sys/racct.h> 74 #include <sys/resourcevar.h> 75 #include <sys/rwlock.h> 76 #include <sys/sched.h> 77 #include <sys/sf_buf.h> 78 #include <sys/shm.h> 79 #include <sys/vmmeter.h> 80 #include <sys/vmem.h> 81 #include <sys/sx.h> 82 #include <sys/sysctl.h> 83 #include <sys/_kstack_cache.h> 84 #include <sys/eventhandler.h> 85 #include <sys/kernel.h> 86 #include <sys/ktr.h> 87 #include <sys/unistd.h> 88 89 #include <vm/vm.h> 90 #include <vm/vm_param.h> 91 #include <vm/pmap.h> 92 #include <vm/vm_map.h> 93 #include <vm/vm_page.h> 94 #include <vm/vm_pageout.h> 95 #include <vm/vm_object.h> 96 #include <vm/vm_kern.h> 97 #include <vm/vm_extern.h> 98 #include <vm/vm_pager.h> 99 #include <vm/swap_pager.h> 100 101 #ifndef NO_SWAPPING 102 static int swapout(struct proc *); 103 static void swapclear(struct proc *); 104 static void vm_thread_swapin(struct thread *td); 105 static void vm_thread_swapout(struct thread *td); 106 #endif 107 108 /* 109 * MPSAFE 110 * 111 * WARNING! This code calls vm_map_check_protection() which only checks 112 * the associated vm_map_entry range. It does not determine whether the 113 * contents of the memory is actually readable or writable. In most cases 114 * just checking the vm_map_entry is sufficient within the kernel's address 115 * space. 116 */ 117 int 118 kernacc(addr, len, rw) 119 void *addr; 120 int len, rw; 121 { 122 boolean_t rv; 123 vm_offset_t saddr, eaddr; 124 vm_prot_t prot; 125 126 KASSERT((rw & ~VM_PROT_ALL) == 0, 127 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 128 129 if ((vm_offset_t)addr + len > kernel_map->max_offset || 130 (vm_offset_t)addr + len < (vm_offset_t)addr) 131 return (FALSE); 132 133 prot = rw; 134 saddr = trunc_page((vm_offset_t)addr); 135 eaddr = round_page((vm_offset_t)addr + len); 136 vm_map_lock_read(kernel_map); 137 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 138 vm_map_unlock_read(kernel_map); 139 return (rv == TRUE); 140 } 141 142 /* 143 * MPSAFE 144 * 145 * WARNING! This code calls vm_map_check_protection() which only checks 146 * the associated vm_map_entry range. It does not determine whether the 147 * contents of the memory is actually readable or writable. vmapbuf(), 148 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 149 * used in conjuction with this call. 150 */ 151 int 152 useracc(addr, len, rw) 153 void *addr; 154 int len, rw; 155 { 156 boolean_t rv; 157 vm_prot_t prot; 158 vm_map_t map; 159 160 KASSERT((rw & ~VM_PROT_ALL) == 0, 161 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 162 prot = rw; 163 map = &curproc->p_vmspace->vm_map; 164 if ((vm_offset_t)addr + len > vm_map_max(map) || 165 (vm_offset_t)addr + len < (vm_offset_t)addr) { 166 return (FALSE); 167 } 168 vm_map_lock_read(map); 169 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 170 round_page((vm_offset_t)addr + len), prot); 171 vm_map_unlock_read(map); 172 return (rv == TRUE); 173 } 174 175 int 176 vslock(void *addr, size_t len) 177 { 178 vm_offset_t end, last, start; 179 vm_size_t npages; 180 int error; 181 182 last = (vm_offset_t)addr + len; 183 start = trunc_page((vm_offset_t)addr); 184 end = round_page(last); 185 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 186 return (EINVAL); 187 npages = atop(end - start); 188 if (npages > vm_page_max_wired) 189 return (ENOMEM); 190 #if 0 191 /* 192 * XXX - not yet 193 * 194 * The limit for transient usage of wired pages should be 195 * larger than for "permanent" wired pages (mlock()). 196 * 197 * Also, the sysctl code, which is the only present user 198 * of vslock(), does a hard loop on EAGAIN. 199 */ 200 if (npages + cnt.v_wire_count > vm_page_max_wired) 201 return (EAGAIN); 202 #endif 203 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 204 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 205 /* 206 * Return EFAULT on error to match copy{in,out}() behaviour 207 * rather than returning ENOMEM like mlock() would. 208 */ 209 return (error == KERN_SUCCESS ? 0 : EFAULT); 210 } 211 212 void 213 vsunlock(void *addr, size_t len) 214 { 215 216 /* Rely on the parameter sanity checks performed by vslock(). */ 217 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 218 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 219 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 220 } 221 222 /* 223 * Pin the page contained within the given object at the given offset. If the 224 * page is not resident, allocate and load it using the given object's pager. 225 * Return the pinned page if successful; otherwise, return NULL. 226 */ 227 static vm_page_t 228 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 229 { 230 vm_page_t m, ma[1]; 231 vm_pindex_t pindex; 232 int rv; 233 234 VM_OBJECT_WLOCK(object); 235 pindex = OFF_TO_IDX(offset); 236 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 237 if (m->valid != VM_PAGE_BITS_ALL) { 238 ma[0] = m; 239 rv = vm_pager_get_pages(object, ma, 1, 0); 240 m = vm_page_lookup(object, pindex); 241 if (m == NULL) 242 goto out; 243 if (rv != VM_PAGER_OK) { 244 vm_page_lock(m); 245 vm_page_free(m); 246 vm_page_unlock(m); 247 m = NULL; 248 goto out; 249 } 250 } 251 vm_page_xunbusy(m); 252 vm_page_lock(m); 253 vm_page_hold(m); 254 vm_page_unlock(m); 255 out: 256 VM_OBJECT_WUNLOCK(object); 257 return (m); 258 } 259 260 /* 261 * Return a CPU private mapping to the page at the given offset within the 262 * given object. The page is pinned before it is mapped. 263 */ 264 struct sf_buf * 265 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 266 { 267 vm_page_t m; 268 269 m = vm_imgact_hold_page(object, offset); 270 if (m == NULL) 271 return (NULL); 272 sched_pin(); 273 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 274 } 275 276 /* 277 * Destroy the given CPU private mapping and unpin the page that it mapped. 278 */ 279 void 280 vm_imgact_unmap_page(struct sf_buf *sf) 281 { 282 vm_page_t m; 283 284 m = sf_buf_page(sf); 285 sf_buf_free(sf); 286 sched_unpin(); 287 vm_page_lock(m); 288 vm_page_unhold(m); 289 vm_page_unlock(m); 290 } 291 292 void 293 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz) 294 { 295 296 pmap_sync_icache(map->pmap, va, sz); 297 } 298 299 struct kstack_cache_entry *kstack_cache; 300 static int kstack_cache_size = 128; 301 static int kstacks; 302 static struct mtx kstack_cache_mtx; 303 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 304 305 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 306 ""); 307 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 308 ""); 309 310 #ifndef KSTACK_MAX_PAGES 311 #define KSTACK_MAX_PAGES 32 312 #endif 313 314 /* 315 * Create the kernel stack (including pcb for i386) for a new thread. 316 * This routine directly affects the fork perf for a process and 317 * create performance for a thread. 318 */ 319 int 320 vm_thread_new(struct thread *td, int pages) 321 { 322 vm_object_t ksobj; 323 vm_offset_t ks; 324 vm_page_t m, ma[KSTACK_MAX_PAGES]; 325 struct kstack_cache_entry *ks_ce; 326 int i; 327 328 /* Bounds check */ 329 if (pages <= 1) 330 pages = KSTACK_PAGES; 331 else if (pages > KSTACK_MAX_PAGES) 332 pages = KSTACK_MAX_PAGES; 333 334 if (pages == KSTACK_PAGES) { 335 mtx_lock(&kstack_cache_mtx); 336 if (kstack_cache != NULL) { 337 ks_ce = kstack_cache; 338 kstack_cache = ks_ce->next_ks_entry; 339 mtx_unlock(&kstack_cache_mtx); 340 341 td->td_kstack_obj = ks_ce->ksobj; 342 td->td_kstack = (vm_offset_t)ks_ce; 343 td->td_kstack_pages = KSTACK_PAGES; 344 return (1); 345 } 346 mtx_unlock(&kstack_cache_mtx); 347 } 348 349 /* 350 * Allocate an object for the kstack. 351 */ 352 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 353 354 /* 355 * Get a kernel virtual address for this thread's kstack. 356 */ 357 #if defined(__mips__) 358 /* 359 * We need to align the kstack's mapped address to fit within 360 * a single TLB entry. 361 */ 362 if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE, 363 PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX, 364 M_BESTFIT | M_NOWAIT, &ks)) { 365 ks = 0; 366 } 367 #else 368 ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 369 #endif 370 if (ks == 0) { 371 printf("vm_thread_new: kstack allocation failed\n"); 372 vm_object_deallocate(ksobj); 373 return (0); 374 } 375 376 atomic_add_int(&kstacks, 1); 377 if (KSTACK_GUARD_PAGES != 0) { 378 pmap_qremove(ks, KSTACK_GUARD_PAGES); 379 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 380 } 381 td->td_kstack_obj = ksobj; 382 td->td_kstack = ks; 383 /* 384 * Knowing the number of pages allocated is useful when you 385 * want to deallocate them. 386 */ 387 td->td_kstack_pages = pages; 388 /* 389 * For the length of the stack, link in a real page of ram for each 390 * page of stack. 391 */ 392 VM_OBJECT_WLOCK(ksobj); 393 for (i = 0; i < pages; i++) { 394 /* 395 * Get a kernel stack page. 396 */ 397 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 398 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 399 ma[i] = m; 400 m->valid = VM_PAGE_BITS_ALL; 401 } 402 VM_OBJECT_WUNLOCK(ksobj); 403 pmap_qenter(ks, ma, pages); 404 return (1); 405 } 406 407 static void 408 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 409 { 410 vm_page_t m; 411 int i; 412 413 atomic_add_int(&kstacks, -1); 414 pmap_qremove(ks, pages); 415 VM_OBJECT_WLOCK(ksobj); 416 for (i = 0; i < pages; i++) { 417 m = vm_page_lookup(ksobj, i); 418 if (m == NULL) 419 panic("vm_thread_dispose: kstack already missing?"); 420 vm_page_lock(m); 421 vm_page_unwire(m, 0); 422 vm_page_free(m); 423 vm_page_unlock(m); 424 } 425 VM_OBJECT_WUNLOCK(ksobj); 426 vm_object_deallocate(ksobj); 427 kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 428 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 429 } 430 431 /* 432 * Dispose of a thread's kernel stack. 433 */ 434 void 435 vm_thread_dispose(struct thread *td) 436 { 437 vm_object_t ksobj; 438 vm_offset_t ks; 439 struct kstack_cache_entry *ks_ce; 440 int pages; 441 442 pages = td->td_kstack_pages; 443 ksobj = td->td_kstack_obj; 444 ks = td->td_kstack; 445 td->td_kstack = 0; 446 td->td_kstack_pages = 0; 447 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 448 ks_ce = (struct kstack_cache_entry *)ks; 449 ks_ce->ksobj = ksobj; 450 mtx_lock(&kstack_cache_mtx); 451 ks_ce->next_ks_entry = kstack_cache; 452 kstack_cache = ks_ce; 453 mtx_unlock(&kstack_cache_mtx); 454 return; 455 } 456 vm_thread_stack_dispose(ksobj, ks, pages); 457 } 458 459 static void 460 vm_thread_stack_lowmem(void *nulll) 461 { 462 struct kstack_cache_entry *ks_ce, *ks_ce1; 463 464 mtx_lock(&kstack_cache_mtx); 465 ks_ce = kstack_cache; 466 kstack_cache = NULL; 467 mtx_unlock(&kstack_cache_mtx); 468 469 while (ks_ce != NULL) { 470 ks_ce1 = ks_ce; 471 ks_ce = ks_ce->next_ks_entry; 472 473 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 474 KSTACK_PAGES); 475 } 476 } 477 478 static void 479 kstack_cache_init(void *nulll) 480 { 481 482 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 483 EVENTHANDLER_PRI_ANY); 484 } 485 486 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 487 488 #ifndef NO_SWAPPING 489 /* 490 * Allow a thread's kernel stack to be paged out. 491 */ 492 static void 493 vm_thread_swapout(struct thread *td) 494 { 495 vm_object_t ksobj; 496 vm_page_t m; 497 int i, pages; 498 499 cpu_thread_swapout(td); 500 pages = td->td_kstack_pages; 501 ksobj = td->td_kstack_obj; 502 pmap_qremove(td->td_kstack, pages); 503 VM_OBJECT_WLOCK(ksobj); 504 for (i = 0; i < pages; i++) { 505 m = vm_page_lookup(ksobj, i); 506 if (m == NULL) 507 panic("vm_thread_swapout: kstack already missing?"); 508 vm_page_dirty(m); 509 vm_page_lock(m); 510 vm_page_unwire(m, 0); 511 vm_page_unlock(m); 512 } 513 VM_OBJECT_WUNLOCK(ksobj); 514 } 515 516 /* 517 * Bring the kernel stack for a specified thread back in. 518 */ 519 static void 520 vm_thread_swapin(struct thread *td) 521 { 522 vm_object_t ksobj; 523 vm_page_t ma[KSTACK_MAX_PAGES]; 524 int i, j, k, pages, rv; 525 526 pages = td->td_kstack_pages; 527 ksobj = td->td_kstack_obj; 528 VM_OBJECT_WLOCK(ksobj); 529 for (i = 0; i < pages; i++) 530 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | 531 VM_ALLOC_WIRED); 532 for (i = 0; i < pages; i++) { 533 if (ma[i]->valid != VM_PAGE_BITS_ALL) { 534 vm_page_assert_xbusied(ma[i]); 535 vm_object_pip_add(ksobj, 1); 536 for (j = i + 1; j < pages; j++) { 537 if (ma[j]->valid != VM_PAGE_BITS_ALL) 538 vm_page_assert_xbusied(ma[j]); 539 if (ma[j]->valid == VM_PAGE_BITS_ALL) 540 break; 541 } 542 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0); 543 if (rv != VM_PAGER_OK) 544 panic("vm_thread_swapin: cannot get kstack for proc: %d", 545 td->td_proc->p_pid); 546 vm_object_pip_wakeup(ksobj); 547 for (k = i; k < j; k++) 548 ma[k] = vm_page_lookup(ksobj, k); 549 vm_page_xunbusy(ma[i]); 550 } else if (vm_page_xbusied(ma[i])) 551 vm_page_xunbusy(ma[i]); 552 } 553 VM_OBJECT_WUNLOCK(ksobj); 554 pmap_qenter(td->td_kstack, ma, pages); 555 cpu_thread_swapin(td); 556 } 557 #endif /* !NO_SWAPPING */ 558 559 /* 560 * Implement fork's actions on an address space. 561 * Here we arrange for the address space to be copied or referenced, 562 * allocate a user struct (pcb and kernel stack), then call the 563 * machine-dependent layer to fill those in and make the new process 564 * ready to run. The new process is set up so that it returns directly 565 * to user mode to avoid stack copying and relocation problems. 566 */ 567 int 568 vm_forkproc(td, p2, td2, vm2, flags) 569 struct thread *td; 570 struct proc *p2; 571 struct thread *td2; 572 struct vmspace *vm2; 573 int flags; 574 { 575 struct proc *p1 = td->td_proc; 576 int error; 577 578 if ((flags & RFPROC) == 0) { 579 /* 580 * Divorce the memory, if it is shared, essentially 581 * this changes shared memory amongst threads, into 582 * COW locally. 583 */ 584 if ((flags & RFMEM) == 0) { 585 if (p1->p_vmspace->vm_refcnt > 1) { 586 error = vmspace_unshare(p1); 587 if (error) 588 return (error); 589 } 590 } 591 cpu_fork(td, p2, td2, flags); 592 return (0); 593 } 594 595 if (flags & RFMEM) { 596 p2->p_vmspace = p1->p_vmspace; 597 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 598 } 599 600 while (vm_page_count_severe()) { 601 VM_WAIT; 602 } 603 604 if ((flags & RFMEM) == 0) { 605 p2->p_vmspace = vm2; 606 if (p1->p_vmspace->vm_shm) 607 shmfork(p1, p2); 608 } 609 610 /* 611 * cpu_fork will copy and update the pcb, set up the kernel stack, 612 * and make the child ready to run. 613 */ 614 cpu_fork(td, p2, td2, flags); 615 return (0); 616 } 617 618 /* 619 * Called after process has been wait(2)'ed apon and is being reaped. 620 * The idea is to reclaim resources that we could not reclaim while 621 * the process was still executing. 622 */ 623 void 624 vm_waitproc(p) 625 struct proc *p; 626 { 627 628 vmspace_exitfree(p); /* and clean-out the vmspace */ 629 } 630 631 void 632 faultin(p) 633 struct proc *p; 634 { 635 #ifdef NO_SWAPPING 636 637 PROC_LOCK_ASSERT(p, MA_OWNED); 638 if ((p->p_flag & P_INMEM) == 0) 639 panic("faultin: proc swapped out with NO_SWAPPING!"); 640 #else /* !NO_SWAPPING */ 641 struct thread *td; 642 643 PROC_LOCK_ASSERT(p, MA_OWNED); 644 /* 645 * If another process is swapping in this process, 646 * just wait until it finishes. 647 */ 648 if (p->p_flag & P_SWAPPINGIN) { 649 while (p->p_flag & P_SWAPPINGIN) 650 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 651 return; 652 } 653 if ((p->p_flag & P_INMEM) == 0) { 654 /* 655 * Don't let another thread swap process p out while we are 656 * busy swapping it in. 657 */ 658 ++p->p_lock; 659 p->p_flag |= P_SWAPPINGIN; 660 PROC_UNLOCK(p); 661 662 /* 663 * We hold no lock here because the list of threads 664 * can not change while all threads in the process are 665 * swapped out. 666 */ 667 FOREACH_THREAD_IN_PROC(p, td) 668 vm_thread_swapin(td); 669 PROC_LOCK(p); 670 swapclear(p); 671 p->p_swtick = ticks; 672 673 wakeup(&p->p_flag); 674 675 /* Allow other threads to swap p out now. */ 676 --p->p_lock; 677 } 678 #endif /* NO_SWAPPING */ 679 } 680 681 /* 682 * This swapin algorithm attempts to swap-in processes only if there 683 * is enough space for them. Of course, if a process waits for a long 684 * time, it will be swapped in anyway. 685 * 686 * Giant is held on entry. 687 */ 688 void 689 swapper(void) 690 { 691 struct proc *p; 692 struct thread *td; 693 struct proc *pp; 694 int slptime; 695 int swtime; 696 int ppri; 697 int pri; 698 699 loop: 700 if (vm_page_count_min()) { 701 VM_WAIT; 702 goto loop; 703 } 704 705 pp = NULL; 706 ppri = INT_MIN; 707 sx_slock(&allproc_lock); 708 FOREACH_PROC_IN_SYSTEM(p) { 709 PROC_LOCK(p); 710 if (p->p_state == PRS_NEW || 711 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 712 PROC_UNLOCK(p); 713 continue; 714 } 715 swtime = (ticks - p->p_swtick) / hz; 716 FOREACH_THREAD_IN_PROC(p, td) { 717 /* 718 * An otherwise runnable thread of a process 719 * swapped out has only the TDI_SWAPPED bit set. 720 * 721 */ 722 thread_lock(td); 723 if (td->td_inhibitors == TDI_SWAPPED) { 724 slptime = (ticks - td->td_slptick) / hz; 725 pri = swtime + slptime; 726 if ((td->td_flags & TDF_SWAPINREQ) == 0) 727 pri -= p->p_nice * 8; 728 /* 729 * if this thread is higher priority 730 * and there is enough space, then select 731 * this process instead of the previous 732 * selection. 733 */ 734 if (pri > ppri) { 735 pp = p; 736 ppri = pri; 737 } 738 } 739 thread_unlock(td); 740 } 741 PROC_UNLOCK(p); 742 } 743 sx_sunlock(&allproc_lock); 744 745 /* 746 * Nothing to do, back to sleep. 747 */ 748 if ((p = pp) == NULL) { 749 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); 750 goto loop; 751 } 752 PROC_LOCK(p); 753 754 /* 755 * Another process may be bringing or may have already 756 * brought this process in while we traverse all threads. 757 * Or, this process may even be being swapped out again. 758 */ 759 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 760 PROC_UNLOCK(p); 761 goto loop; 762 } 763 764 /* 765 * We would like to bring someone in. (only if there is space). 766 * [What checks the space? ] 767 */ 768 faultin(p); 769 PROC_UNLOCK(p); 770 goto loop; 771 } 772 773 void 774 kick_proc0(void) 775 { 776 777 wakeup(&proc0); 778 } 779 780 #ifndef NO_SWAPPING 781 782 /* 783 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 784 */ 785 static int swap_idle_threshold1 = 2; 786 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 787 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 788 789 /* 790 * Swap_idle_threshold2 is the time that a process can be idle before 791 * it will be swapped out, if idle swapping is enabled. 792 */ 793 static int swap_idle_threshold2 = 10; 794 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 795 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 796 797 /* 798 * First, if any processes have been sleeping or stopped for at least 799 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 800 * no such processes exist, then the longest-sleeping or stopped 801 * process is swapped out. Finally, and only as a last resort, if 802 * there are no sleeping or stopped processes, the longest-resident 803 * process is swapped out. 804 */ 805 void 806 swapout_procs(action) 807 int action; 808 { 809 struct proc *p; 810 struct thread *td; 811 int didswap = 0; 812 813 retry: 814 sx_slock(&allproc_lock); 815 FOREACH_PROC_IN_SYSTEM(p) { 816 struct vmspace *vm; 817 int minslptime = 100000; 818 int slptime; 819 820 /* 821 * Watch out for a process in 822 * creation. It may have no 823 * address space or lock yet. 824 */ 825 if (p->p_state == PRS_NEW) 826 continue; 827 /* 828 * An aio daemon switches its 829 * address space while running. 830 * Perform a quick check whether 831 * a process has P_SYSTEM. 832 */ 833 if ((p->p_flag & P_SYSTEM) != 0) 834 continue; 835 /* 836 * Do not swapout a process that 837 * is waiting for VM data 838 * structures as there is a possible 839 * deadlock. Test this first as 840 * this may block. 841 * 842 * Lock the map until swapout 843 * finishes, or a thread of this 844 * process may attempt to alter 845 * the map. 846 */ 847 vm = vmspace_acquire_ref(p); 848 if (vm == NULL) 849 continue; 850 if (!vm_map_trylock(&vm->vm_map)) 851 goto nextproc1; 852 853 PROC_LOCK(p); 854 if (p->p_lock != 0 || 855 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 856 ) != 0) { 857 goto nextproc; 858 } 859 /* 860 * only aiod changes vmspace, however it will be 861 * skipped because of the if statement above checking 862 * for P_SYSTEM 863 */ 864 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 865 goto nextproc; 866 867 switch (p->p_state) { 868 default: 869 /* Don't swap out processes in any sort 870 * of 'special' state. */ 871 break; 872 873 case PRS_NORMAL: 874 /* 875 * do not swapout a realtime process 876 * Check all the thread groups.. 877 */ 878 FOREACH_THREAD_IN_PROC(p, td) { 879 thread_lock(td); 880 if (PRI_IS_REALTIME(td->td_pri_class)) { 881 thread_unlock(td); 882 goto nextproc; 883 } 884 slptime = (ticks - td->td_slptick) / hz; 885 /* 886 * Guarantee swap_idle_threshold1 887 * time in memory. 888 */ 889 if (slptime < swap_idle_threshold1) { 890 thread_unlock(td); 891 goto nextproc; 892 } 893 894 /* 895 * Do not swapout a process if it is 896 * waiting on a critical event of some 897 * kind or there is a thread whose 898 * pageable memory may be accessed. 899 * 900 * This could be refined to support 901 * swapping out a thread. 902 */ 903 if (!thread_safetoswapout(td)) { 904 thread_unlock(td); 905 goto nextproc; 906 } 907 /* 908 * If the system is under memory stress, 909 * or if we are swapping 910 * idle processes >= swap_idle_threshold2, 911 * then swap the process out. 912 */ 913 if (((action & VM_SWAP_NORMAL) == 0) && 914 (((action & VM_SWAP_IDLE) == 0) || 915 (slptime < swap_idle_threshold2))) { 916 thread_unlock(td); 917 goto nextproc; 918 } 919 920 if (minslptime > slptime) 921 minslptime = slptime; 922 thread_unlock(td); 923 } 924 925 /* 926 * If the pageout daemon didn't free enough pages, 927 * or if this process is idle and the system is 928 * configured to swap proactively, swap it out. 929 */ 930 if ((action & VM_SWAP_NORMAL) || 931 ((action & VM_SWAP_IDLE) && 932 (minslptime > swap_idle_threshold2))) { 933 if (swapout(p) == 0) 934 didswap++; 935 PROC_UNLOCK(p); 936 vm_map_unlock(&vm->vm_map); 937 vmspace_free(vm); 938 sx_sunlock(&allproc_lock); 939 goto retry; 940 } 941 } 942 nextproc: 943 PROC_UNLOCK(p); 944 vm_map_unlock(&vm->vm_map); 945 nextproc1: 946 vmspace_free(vm); 947 continue; 948 } 949 sx_sunlock(&allproc_lock); 950 /* 951 * If we swapped something out, and another process needed memory, 952 * then wakeup the sched process. 953 */ 954 if (didswap) 955 wakeup(&proc0); 956 } 957 958 static void 959 swapclear(p) 960 struct proc *p; 961 { 962 struct thread *td; 963 964 PROC_LOCK_ASSERT(p, MA_OWNED); 965 966 FOREACH_THREAD_IN_PROC(p, td) { 967 thread_lock(td); 968 td->td_flags |= TDF_INMEM; 969 td->td_flags &= ~TDF_SWAPINREQ; 970 TD_CLR_SWAPPED(td); 971 if (TD_CAN_RUN(td)) 972 if (setrunnable(td)) { 973 #ifdef INVARIANTS 974 /* 975 * XXX: We just cleared TDI_SWAPPED 976 * above and set TDF_INMEM, so this 977 * should never happen. 978 */ 979 panic("not waking up swapper"); 980 #endif 981 } 982 thread_unlock(td); 983 } 984 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 985 p->p_flag |= P_INMEM; 986 } 987 988 static int 989 swapout(p) 990 struct proc *p; 991 { 992 struct thread *td; 993 994 PROC_LOCK_ASSERT(p, MA_OWNED); 995 #if defined(SWAP_DEBUG) 996 printf("swapping out %d\n", p->p_pid); 997 #endif 998 999 /* 1000 * The states of this process and its threads may have changed 1001 * by now. Assuming that there is only one pageout daemon thread, 1002 * this process should still be in memory. 1003 */ 1004 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1005 ("swapout: lost a swapout race?")); 1006 1007 /* 1008 * remember the process resident count 1009 */ 1010 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1011 /* 1012 * Check and mark all threads before we proceed. 1013 */ 1014 p->p_flag &= ~P_INMEM; 1015 p->p_flag |= P_SWAPPINGOUT; 1016 FOREACH_THREAD_IN_PROC(p, td) { 1017 thread_lock(td); 1018 if (!thread_safetoswapout(td)) { 1019 thread_unlock(td); 1020 swapclear(p); 1021 return (EBUSY); 1022 } 1023 td->td_flags &= ~TDF_INMEM; 1024 TD_SET_SWAPPED(td); 1025 thread_unlock(td); 1026 } 1027 td = FIRST_THREAD_IN_PROC(p); 1028 ++td->td_ru.ru_nswap; 1029 PROC_UNLOCK(p); 1030 1031 /* 1032 * This list is stable because all threads are now prevented from 1033 * running. The list is only modified in the context of a running 1034 * thread in this process. 1035 */ 1036 FOREACH_THREAD_IN_PROC(p, td) 1037 vm_thread_swapout(td); 1038 1039 PROC_LOCK(p); 1040 p->p_flag &= ~P_SWAPPINGOUT; 1041 p->p_swtick = ticks; 1042 return (0); 1043 } 1044 #endif /* !NO_SWAPPING */
Cache object: 3f8bbf88cebd75a331b059c7808be79d
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