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/11.0/sys/vm/vm_glue.c 302089 2016-06-22 20:15:37Z kib $"); 61 62 #include "opt_vm.h" 63 #include "opt_kstack_pages.h" 64 #include "opt_kstack_max_pages.h" 65 #include "opt_kstack_usage_prof.h" 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/limits.h> 70 #include <sys/lock.h> 71 #include <sys/malloc.h> 72 #include <sys/mutex.h> 73 #include <sys/proc.h> 74 #include <sys/racct.h> 75 #include <sys/resourcevar.h> 76 #include <sys/rwlock.h> 77 #include <sys/sched.h> 78 #include <sys/sf_buf.h> 79 #include <sys/shm.h> 80 #include <sys/vmmeter.h> 81 #include <sys/vmem.h> 82 #include <sys/sx.h> 83 #include <sys/sysctl.h> 84 #include <sys/_kstack_cache.h> 85 #include <sys/eventhandler.h> 86 #include <sys/kernel.h> 87 #include <sys/ktr.h> 88 #include <sys/unistd.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_page.h> 95 #include <vm/vm_pageout.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_kern.h> 98 #include <vm/vm_extern.h> 99 #include <vm/vm_pager.h> 100 #include <vm/swap_pager.h> 101 102 #include <machine/cpu.h> 103 104 #ifndef NO_SWAPPING 105 static int swapout(struct proc *); 106 static void swapclear(struct proc *); 107 static void vm_thread_swapin(struct thread *td); 108 static void vm_thread_swapout(struct thread *td); 109 #endif 110 111 /* 112 * MPSAFE 113 * 114 * WARNING! This code calls vm_map_check_protection() which only checks 115 * the associated vm_map_entry range. It does not determine whether the 116 * contents of the memory is actually readable or writable. In most cases 117 * just checking the vm_map_entry is sufficient within the kernel's address 118 * space. 119 */ 120 int 121 kernacc(addr, len, rw) 122 void *addr; 123 int len, rw; 124 { 125 boolean_t rv; 126 vm_offset_t saddr, eaddr; 127 vm_prot_t prot; 128 129 KASSERT((rw & ~VM_PROT_ALL) == 0, 130 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 131 132 if ((vm_offset_t)addr + len > kernel_map->max_offset || 133 (vm_offset_t)addr + len < (vm_offset_t)addr) 134 return (FALSE); 135 136 prot = rw; 137 saddr = trunc_page((vm_offset_t)addr); 138 eaddr = round_page((vm_offset_t)addr + len); 139 vm_map_lock_read(kernel_map); 140 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 141 vm_map_unlock_read(kernel_map); 142 return (rv == TRUE); 143 } 144 145 /* 146 * MPSAFE 147 * 148 * WARNING! This code calls vm_map_check_protection() which only checks 149 * the associated vm_map_entry range. It does not determine whether the 150 * contents of the memory is actually readable or writable. vmapbuf(), 151 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 152 * used in conjunction with this call. 153 */ 154 int 155 useracc(addr, len, rw) 156 void *addr; 157 int len, rw; 158 { 159 boolean_t rv; 160 vm_prot_t prot; 161 vm_map_t map; 162 163 KASSERT((rw & ~VM_PROT_ALL) == 0, 164 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 165 prot = rw; 166 map = &curproc->p_vmspace->vm_map; 167 if ((vm_offset_t)addr + len > vm_map_max(map) || 168 (vm_offset_t)addr + len < (vm_offset_t)addr) { 169 return (FALSE); 170 } 171 vm_map_lock_read(map); 172 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 173 round_page((vm_offset_t)addr + len), prot); 174 vm_map_unlock_read(map); 175 return (rv == TRUE); 176 } 177 178 int 179 vslock(void *addr, size_t len) 180 { 181 vm_offset_t end, last, start; 182 vm_size_t npages; 183 int error; 184 185 last = (vm_offset_t)addr + len; 186 start = trunc_page((vm_offset_t)addr); 187 end = round_page(last); 188 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 189 return (EINVAL); 190 npages = atop(end - start); 191 if (npages > vm_page_max_wired) 192 return (ENOMEM); 193 #if 0 194 /* 195 * XXX - not yet 196 * 197 * The limit for transient usage of wired pages should be 198 * larger than for "permanent" wired pages (mlock()). 199 * 200 * Also, the sysctl code, which is the only present user 201 * of vslock(), does a hard loop on EAGAIN. 202 */ 203 if (npages + vm_cnt.v_wire_count > vm_page_max_wired) 204 return (EAGAIN); 205 #endif 206 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 207 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 208 /* 209 * Return EFAULT on error to match copy{in,out}() behaviour 210 * rather than returning ENOMEM like mlock() would. 211 */ 212 return (error == KERN_SUCCESS ? 0 : EFAULT); 213 } 214 215 void 216 vsunlock(void *addr, size_t len) 217 { 218 219 /* Rely on the parameter sanity checks performed by vslock(). */ 220 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 221 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 222 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 223 } 224 225 /* 226 * Pin the page contained within the given object at the given offset. If the 227 * page is not resident, allocate and load it using the given object's pager. 228 * Return the pinned page if successful; otherwise, return NULL. 229 */ 230 static vm_page_t 231 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 232 { 233 vm_page_t m; 234 vm_pindex_t pindex; 235 int rv; 236 237 VM_OBJECT_WLOCK(object); 238 pindex = OFF_TO_IDX(offset); 239 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 240 if (m->valid != VM_PAGE_BITS_ALL) { 241 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL); 242 if (rv != VM_PAGER_OK) { 243 vm_page_lock(m); 244 vm_page_free(m); 245 vm_page_unlock(m); 246 m = NULL; 247 goto out; 248 } 249 } 250 vm_page_xunbusy(m); 251 vm_page_lock(m); 252 vm_page_hold(m); 253 vm_page_activate(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, PQ_NONE); 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 #ifdef KSTACK_USAGE_PROF 489 /* 490 * Track maximum stack used by a thread in kernel. 491 */ 492 static int max_kstack_used; 493 494 SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD, 495 &max_kstack_used, 0, 496 "Maxiumum stack depth used by a thread in kernel"); 497 498 void 499 intr_prof_stack_use(struct thread *td, struct trapframe *frame) 500 { 501 vm_offset_t stack_top; 502 vm_offset_t current; 503 int used, prev_used; 504 505 /* 506 * Testing for interrupted kernel mode isn't strictly 507 * needed. It optimizes the execution, since interrupts from 508 * usermode will have only the trap frame on the stack. 509 */ 510 if (TRAPF_USERMODE(frame)) 511 return; 512 513 stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE; 514 current = (vm_offset_t)(uintptr_t)&stack_top; 515 516 /* 517 * Try to detect if interrupt is using kernel thread stack. 518 * Hardware could use a dedicated stack for interrupt handling. 519 */ 520 if (stack_top <= current || current < td->td_kstack) 521 return; 522 523 used = stack_top - current; 524 for (;;) { 525 prev_used = max_kstack_used; 526 if (prev_used >= used) 527 break; 528 if (atomic_cmpset_int(&max_kstack_used, prev_used, used)) 529 break; 530 } 531 } 532 #endif /* KSTACK_USAGE_PROF */ 533 534 #ifndef NO_SWAPPING 535 /* 536 * Allow a thread's kernel stack to be paged out. 537 */ 538 static void 539 vm_thread_swapout(struct thread *td) 540 { 541 vm_object_t ksobj; 542 vm_page_t m; 543 int i, pages; 544 545 cpu_thread_swapout(td); 546 pages = td->td_kstack_pages; 547 ksobj = td->td_kstack_obj; 548 pmap_qremove(td->td_kstack, pages); 549 VM_OBJECT_WLOCK(ksobj); 550 for (i = 0; i < pages; i++) { 551 m = vm_page_lookup(ksobj, i); 552 if (m == NULL) 553 panic("vm_thread_swapout: kstack already missing?"); 554 vm_page_dirty(m); 555 vm_page_lock(m); 556 vm_page_unwire(m, PQ_INACTIVE); 557 vm_page_unlock(m); 558 } 559 VM_OBJECT_WUNLOCK(ksobj); 560 } 561 562 /* 563 * Bring the kernel stack for a specified thread back in. 564 */ 565 static void 566 vm_thread_swapin(struct thread *td) 567 { 568 vm_object_t ksobj; 569 vm_page_t ma[KSTACK_MAX_PAGES]; 570 int pages; 571 572 pages = td->td_kstack_pages; 573 ksobj = td->td_kstack_obj; 574 VM_OBJECT_WLOCK(ksobj); 575 for (int i = 0; i < pages; i++) 576 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | 577 VM_ALLOC_WIRED); 578 for (int i = 0; i < pages;) { 579 int j, a, count, rv; 580 581 vm_page_assert_xbusied(ma[i]); 582 if (ma[i]->valid == VM_PAGE_BITS_ALL) { 583 vm_page_xunbusy(ma[i]); 584 i++; 585 continue; 586 } 587 vm_object_pip_add(ksobj, 1); 588 for (j = i + 1; j < pages; j++) 589 if (ma[j]->valid == VM_PAGE_BITS_ALL) 590 break; 591 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 592 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 593 count = min(a + 1, j - i); 594 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 595 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 596 __func__, td->td_proc->p_pid)); 597 vm_object_pip_wakeup(ksobj); 598 for (j = i; j < i + count; j++) 599 vm_page_xunbusy(ma[j]); 600 i += count; 601 } 602 VM_OBJECT_WUNLOCK(ksobj); 603 pmap_qenter(td->td_kstack, ma, pages); 604 cpu_thread_swapin(td); 605 } 606 #endif /* !NO_SWAPPING */ 607 608 /* 609 * Implement fork's actions on an address space. 610 * Here we arrange for the address space to be copied or referenced, 611 * allocate a user struct (pcb and kernel stack), then call the 612 * machine-dependent layer to fill those in and make the new process 613 * ready to run. The new process is set up so that it returns directly 614 * to user mode to avoid stack copying and relocation problems. 615 */ 616 int 617 vm_forkproc(td, p2, td2, vm2, flags) 618 struct thread *td; 619 struct proc *p2; 620 struct thread *td2; 621 struct vmspace *vm2; 622 int flags; 623 { 624 struct proc *p1 = td->td_proc; 625 int error; 626 627 if ((flags & RFPROC) == 0) { 628 /* 629 * Divorce the memory, if it is shared, essentially 630 * this changes shared memory amongst threads, into 631 * COW locally. 632 */ 633 if ((flags & RFMEM) == 0) { 634 if (p1->p_vmspace->vm_refcnt > 1) { 635 error = vmspace_unshare(p1); 636 if (error) 637 return (error); 638 } 639 } 640 cpu_fork(td, p2, td2, flags); 641 return (0); 642 } 643 644 if (flags & RFMEM) { 645 p2->p_vmspace = p1->p_vmspace; 646 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 647 } 648 649 while (vm_page_count_severe()) { 650 VM_WAIT; 651 } 652 653 if ((flags & RFMEM) == 0) { 654 p2->p_vmspace = vm2; 655 if (p1->p_vmspace->vm_shm) 656 shmfork(p1, p2); 657 } 658 659 /* 660 * cpu_fork will copy and update the pcb, set up the kernel stack, 661 * and make the child ready to run. 662 */ 663 cpu_fork(td, p2, td2, flags); 664 return (0); 665 } 666 667 /* 668 * Called after process has been wait(2)'ed upon and is being reaped. 669 * The idea is to reclaim resources that we could not reclaim while 670 * the process was still executing. 671 */ 672 void 673 vm_waitproc(p) 674 struct proc *p; 675 { 676 677 vmspace_exitfree(p); /* and clean-out the vmspace */ 678 } 679 680 void 681 faultin(p) 682 struct proc *p; 683 { 684 #ifdef NO_SWAPPING 685 686 PROC_LOCK_ASSERT(p, MA_OWNED); 687 if ((p->p_flag & P_INMEM) == 0) 688 panic("faultin: proc swapped out with NO_SWAPPING!"); 689 #else /* !NO_SWAPPING */ 690 struct thread *td; 691 692 PROC_LOCK_ASSERT(p, MA_OWNED); 693 /* 694 * If another process is swapping in this process, 695 * just wait until it finishes. 696 */ 697 if (p->p_flag & P_SWAPPINGIN) { 698 while (p->p_flag & P_SWAPPINGIN) 699 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 700 return; 701 } 702 if ((p->p_flag & P_INMEM) == 0) { 703 /* 704 * Don't let another thread swap process p out while we are 705 * busy swapping it in. 706 */ 707 ++p->p_lock; 708 p->p_flag |= P_SWAPPINGIN; 709 PROC_UNLOCK(p); 710 711 /* 712 * We hold no lock here because the list of threads 713 * can not change while all threads in the process are 714 * swapped out. 715 */ 716 FOREACH_THREAD_IN_PROC(p, td) 717 vm_thread_swapin(td); 718 PROC_LOCK(p); 719 swapclear(p); 720 p->p_swtick = ticks; 721 722 wakeup(&p->p_flag); 723 724 /* Allow other threads to swap p out now. */ 725 --p->p_lock; 726 } 727 #endif /* NO_SWAPPING */ 728 } 729 730 /* 731 * This swapin algorithm attempts to swap-in processes only if there 732 * is enough space for them. Of course, if a process waits for a long 733 * time, it will be swapped in anyway. 734 */ 735 void 736 swapper(void) 737 { 738 struct proc *p; 739 struct thread *td; 740 struct proc *pp; 741 int slptime; 742 int swtime; 743 int ppri; 744 int pri; 745 746 loop: 747 if (vm_page_count_min()) { 748 VM_WAIT; 749 goto loop; 750 } 751 752 pp = NULL; 753 ppri = INT_MIN; 754 sx_slock(&allproc_lock); 755 FOREACH_PROC_IN_SYSTEM(p) { 756 PROC_LOCK(p); 757 if (p->p_state == PRS_NEW || 758 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 759 PROC_UNLOCK(p); 760 continue; 761 } 762 swtime = (ticks - p->p_swtick) / hz; 763 FOREACH_THREAD_IN_PROC(p, td) { 764 /* 765 * An otherwise runnable thread of a process 766 * swapped out has only the TDI_SWAPPED bit set. 767 * 768 */ 769 thread_lock(td); 770 if (td->td_inhibitors == TDI_SWAPPED) { 771 slptime = (ticks - td->td_slptick) / hz; 772 pri = swtime + slptime; 773 if ((td->td_flags & TDF_SWAPINREQ) == 0) 774 pri -= p->p_nice * 8; 775 /* 776 * if this thread is higher priority 777 * and there is enough space, then select 778 * this process instead of the previous 779 * selection. 780 */ 781 if (pri > ppri) { 782 pp = p; 783 ppri = pri; 784 } 785 } 786 thread_unlock(td); 787 } 788 PROC_UNLOCK(p); 789 } 790 sx_sunlock(&allproc_lock); 791 792 /* 793 * Nothing to do, back to sleep. 794 */ 795 if ((p = pp) == NULL) { 796 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2); 797 goto loop; 798 } 799 PROC_LOCK(p); 800 801 /* 802 * Another process may be bringing or may have already 803 * brought this process in while we traverse all threads. 804 * Or, this process may even be being swapped out again. 805 */ 806 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 807 PROC_UNLOCK(p); 808 goto loop; 809 } 810 811 /* 812 * We would like to bring someone in. (only if there is space). 813 * [What checks the space? ] 814 */ 815 faultin(p); 816 PROC_UNLOCK(p); 817 goto loop; 818 } 819 820 void 821 kick_proc0(void) 822 { 823 824 wakeup(&proc0); 825 } 826 827 #ifndef NO_SWAPPING 828 829 /* 830 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 831 */ 832 static int swap_idle_threshold1 = 2; 833 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 834 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 835 836 /* 837 * Swap_idle_threshold2 is the time that a process can be idle before 838 * it will be swapped out, if idle swapping is enabled. 839 */ 840 static int swap_idle_threshold2 = 10; 841 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 842 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 843 844 /* 845 * First, if any processes have been sleeping or stopped for at least 846 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 847 * no such processes exist, then the longest-sleeping or stopped 848 * process is swapped out. Finally, and only as a last resort, if 849 * there are no sleeping or stopped processes, the longest-resident 850 * process is swapped out. 851 */ 852 void 853 swapout_procs(action) 854 int action; 855 { 856 struct proc *p; 857 struct thread *td; 858 int didswap = 0; 859 860 retry: 861 sx_slock(&allproc_lock); 862 FOREACH_PROC_IN_SYSTEM(p) { 863 struct vmspace *vm; 864 int minslptime = 100000; 865 int slptime; 866 867 PROC_LOCK(p); 868 /* 869 * Watch out for a process in 870 * creation. It may have no 871 * address space or lock yet. 872 */ 873 if (p->p_state == PRS_NEW) { 874 PROC_UNLOCK(p); 875 continue; 876 } 877 /* 878 * An aio daemon switches its 879 * address space while running. 880 * Perform a quick check whether 881 * a process has P_SYSTEM. 882 * Filter out exiting processes. 883 */ 884 if ((p->p_flag & (P_SYSTEM | P_WEXIT)) != 0) { 885 PROC_UNLOCK(p); 886 continue; 887 } 888 _PHOLD_LITE(p); 889 PROC_UNLOCK(p); 890 sx_sunlock(&allproc_lock); 891 892 /* 893 * Do not swapout a process that 894 * is waiting for VM data 895 * structures as there is a possible 896 * deadlock. Test this first as 897 * this may block. 898 * 899 * Lock the map until swapout 900 * finishes, or a thread of this 901 * process may attempt to alter 902 * the map. 903 */ 904 vm = vmspace_acquire_ref(p); 905 if (vm == NULL) 906 goto nextproc2; 907 if (!vm_map_trylock(&vm->vm_map)) 908 goto nextproc1; 909 910 PROC_LOCK(p); 911 if (p->p_lock != 1 || (p->p_flag & (P_STOPPED_SINGLE | 912 P_TRACED | P_SYSTEM)) != 0) 913 goto nextproc; 914 915 /* 916 * only aiod changes vmspace, however it will be 917 * skipped because of the if statement above checking 918 * for P_SYSTEM 919 */ 920 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 921 goto nextproc; 922 923 switch (p->p_state) { 924 default: 925 /* Don't swap out processes in any sort 926 * of 'special' state. */ 927 break; 928 929 case PRS_NORMAL: 930 /* 931 * do not swapout a realtime process 932 * Check all the thread groups.. 933 */ 934 FOREACH_THREAD_IN_PROC(p, td) { 935 thread_lock(td); 936 if (PRI_IS_REALTIME(td->td_pri_class)) { 937 thread_unlock(td); 938 goto nextproc; 939 } 940 slptime = (ticks - td->td_slptick) / hz; 941 /* 942 * Guarantee swap_idle_threshold1 943 * time in memory. 944 */ 945 if (slptime < swap_idle_threshold1) { 946 thread_unlock(td); 947 goto nextproc; 948 } 949 950 /* 951 * Do not swapout a process if it is 952 * waiting on a critical event of some 953 * kind or there is a thread whose 954 * pageable memory may be accessed. 955 * 956 * This could be refined to support 957 * swapping out a thread. 958 */ 959 if (!thread_safetoswapout(td)) { 960 thread_unlock(td); 961 goto nextproc; 962 } 963 /* 964 * If the system is under memory stress, 965 * or if we are swapping 966 * idle processes >= swap_idle_threshold2, 967 * then swap the process out. 968 */ 969 if (((action & VM_SWAP_NORMAL) == 0) && 970 (((action & VM_SWAP_IDLE) == 0) || 971 (slptime < swap_idle_threshold2))) { 972 thread_unlock(td); 973 goto nextproc; 974 } 975 976 if (minslptime > slptime) 977 minslptime = slptime; 978 thread_unlock(td); 979 } 980 981 /* 982 * If the pageout daemon didn't free enough pages, 983 * or if this process is idle and the system is 984 * configured to swap proactively, swap it out. 985 */ 986 if ((action & VM_SWAP_NORMAL) || 987 ((action & VM_SWAP_IDLE) && 988 (minslptime > swap_idle_threshold2))) { 989 _PRELE(p); 990 if (swapout(p) == 0) 991 didswap++; 992 PROC_UNLOCK(p); 993 vm_map_unlock(&vm->vm_map); 994 vmspace_free(vm); 995 goto retry; 996 } 997 } 998 nextproc: 999 PROC_UNLOCK(p); 1000 vm_map_unlock(&vm->vm_map); 1001 nextproc1: 1002 vmspace_free(vm); 1003 nextproc2: 1004 sx_slock(&allproc_lock); 1005 PRELE(p); 1006 } 1007 sx_sunlock(&allproc_lock); 1008 /* 1009 * If we swapped something out, and another process needed memory, 1010 * then wakeup the sched process. 1011 */ 1012 if (didswap) 1013 wakeup(&proc0); 1014 } 1015 1016 static void 1017 swapclear(p) 1018 struct proc *p; 1019 { 1020 struct thread *td; 1021 1022 PROC_LOCK_ASSERT(p, MA_OWNED); 1023 1024 FOREACH_THREAD_IN_PROC(p, td) { 1025 thread_lock(td); 1026 td->td_flags |= TDF_INMEM; 1027 td->td_flags &= ~TDF_SWAPINREQ; 1028 TD_CLR_SWAPPED(td); 1029 if (TD_CAN_RUN(td)) 1030 if (setrunnable(td)) { 1031 #ifdef INVARIANTS 1032 /* 1033 * XXX: We just cleared TDI_SWAPPED 1034 * above and set TDF_INMEM, so this 1035 * should never happen. 1036 */ 1037 panic("not waking up swapper"); 1038 #endif 1039 } 1040 thread_unlock(td); 1041 } 1042 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 1043 p->p_flag |= P_INMEM; 1044 } 1045 1046 static int 1047 swapout(p) 1048 struct proc *p; 1049 { 1050 struct thread *td; 1051 1052 PROC_LOCK_ASSERT(p, MA_OWNED); 1053 #if defined(SWAP_DEBUG) 1054 printf("swapping out %d\n", p->p_pid); 1055 #endif 1056 1057 /* 1058 * The states of this process and its threads may have changed 1059 * by now. Assuming that there is only one pageout daemon thread, 1060 * this process should still be in memory. 1061 */ 1062 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1063 ("swapout: lost a swapout race?")); 1064 1065 /* 1066 * remember the process resident count 1067 */ 1068 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1069 /* 1070 * Check and mark all threads before we proceed. 1071 */ 1072 p->p_flag &= ~P_INMEM; 1073 p->p_flag |= P_SWAPPINGOUT; 1074 FOREACH_THREAD_IN_PROC(p, td) { 1075 thread_lock(td); 1076 if (!thread_safetoswapout(td)) { 1077 thread_unlock(td); 1078 swapclear(p); 1079 return (EBUSY); 1080 } 1081 td->td_flags &= ~TDF_INMEM; 1082 TD_SET_SWAPPED(td); 1083 thread_unlock(td); 1084 } 1085 td = FIRST_THREAD_IN_PROC(p); 1086 ++td->td_ru.ru_nswap; 1087 PROC_UNLOCK(p); 1088 1089 /* 1090 * This list is stable because all threads are now prevented from 1091 * running. The list is only modified in the context of a running 1092 * thread in this process. 1093 */ 1094 FOREACH_THREAD_IN_PROC(p, td) 1095 vm_thread_swapout(td); 1096 1097 PROC_LOCK(p); 1098 p->p_flag &= ~P_SWAPPINGOUT; 1099 p->p_swtick = ticks; 1100 return (0); 1101 } 1102 #endif /* !NO_SWAPPING */
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