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/9.2/sys/vm/vm_glue.c 240499 2012-09-14 13:56:50Z zont $"); 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/mutex.h> 71 #include <sys/proc.h> 72 #include <sys/racct.h> 73 #include <sys/resourcevar.h> 74 #include <sys/sched.h> 75 #include <sys/sf_buf.h> 76 #include <sys/shm.h> 77 #include <sys/vmmeter.h> 78 #include <sys/sx.h> 79 #include <sys/sysctl.h> 80 #include <sys/_kstack_cache.h> 81 #include <sys/eventhandler.h> 82 #include <sys/kernel.h> 83 #include <sys/ktr.h> 84 #include <sys/unistd.h> 85 86 #include <vm/vm.h> 87 #include <vm/vm_param.h> 88 #include <vm/pmap.h> 89 #include <vm/vm_map.h> 90 #include <vm/vm_page.h> 91 #include <vm/vm_pageout.h> 92 #include <vm/vm_object.h> 93 #include <vm/vm_kern.h> 94 #include <vm/vm_extern.h> 95 #include <vm/vm_pager.h> 96 #include <vm/swap_pager.h> 97 98 /* 99 * System initialization 100 * 101 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 102 * 103 * Note: run scheduling should be divorced from the vm system. 104 */ 105 static void scheduler(void *); 106 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL); 107 108 #ifndef NO_SWAPPING 109 static int swapout(struct proc *); 110 static void swapclear(struct proc *); 111 static void vm_thread_swapin(struct thread *td); 112 static void vm_thread_swapout(struct thread *td); 113 #endif 114 115 /* 116 * MPSAFE 117 * 118 * WARNING! This code calls vm_map_check_protection() which only checks 119 * the associated vm_map_entry range. It does not determine whether the 120 * contents of the memory is actually readable or writable. In most cases 121 * just checking the vm_map_entry is sufficient within the kernel's address 122 * space. 123 */ 124 int 125 kernacc(addr, len, rw) 126 void *addr; 127 int len, rw; 128 { 129 boolean_t rv; 130 vm_offset_t saddr, eaddr; 131 vm_prot_t prot; 132 133 KASSERT((rw & ~VM_PROT_ALL) == 0, 134 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 135 136 if ((vm_offset_t)addr + len > kernel_map->max_offset || 137 (vm_offset_t)addr + len < (vm_offset_t)addr) 138 return (FALSE); 139 140 prot = rw; 141 saddr = trunc_page((vm_offset_t)addr); 142 eaddr = round_page((vm_offset_t)addr + len); 143 vm_map_lock_read(kernel_map); 144 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 145 vm_map_unlock_read(kernel_map); 146 return (rv == TRUE); 147 } 148 149 /* 150 * MPSAFE 151 * 152 * WARNING! This code calls vm_map_check_protection() which only checks 153 * the associated vm_map_entry range. It does not determine whether the 154 * contents of the memory is actually readable or writable. vmapbuf(), 155 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 156 * used in conjuction with this call. 157 */ 158 int 159 useracc(addr, len, rw) 160 void *addr; 161 int len, rw; 162 { 163 boolean_t rv; 164 vm_prot_t prot; 165 vm_map_t map; 166 167 KASSERT((rw & ~VM_PROT_ALL) == 0, 168 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 169 prot = rw; 170 map = &curproc->p_vmspace->vm_map; 171 if ((vm_offset_t)addr + len > vm_map_max(map) || 172 (vm_offset_t)addr + len < (vm_offset_t)addr) { 173 return (FALSE); 174 } 175 vm_map_lock_read(map); 176 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 177 round_page((vm_offset_t)addr + len), prot); 178 vm_map_unlock_read(map); 179 return (rv == TRUE); 180 } 181 182 int 183 vslock(void *addr, size_t len) 184 { 185 vm_offset_t end, last, start; 186 vm_size_t npages; 187 int error; 188 189 last = (vm_offset_t)addr + len; 190 start = trunc_page((vm_offset_t)addr); 191 end = round_page(last); 192 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 193 return (EINVAL); 194 npages = atop(end - start); 195 if (npages > vm_page_max_wired) 196 return (ENOMEM); 197 #if 0 198 /* 199 * XXX - not yet 200 * 201 * The limit for transient usage of wired pages should be 202 * larger than for "permanent" wired pages (mlock()). 203 * 204 * Also, the sysctl code, which is the only present user 205 * of vslock(), does a hard loop on EAGAIN. 206 */ 207 if (npages + cnt.v_wire_count > vm_page_max_wired) 208 return (EAGAIN); 209 #endif 210 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 211 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 212 /* 213 * Return EFAULT on error to match copy{in,out}() behaviour 214 * rather than returning ENOMEM like mlock() would. 215 */ 216 return (error == KERN_SUCCESS ? 0 : EFAULT); 217 } 218 219 void 220 vsunlock(void *addr, size_t len) 221 { 222 223 /* Rely on the parameter sanity checks performed by vslock(). */ 224 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 225 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 226 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 227 } 228 229 /* 230 * Pin the page contained within the given object at the given offset. If the 231 * page is not resident, allocate and load it using the given object's pager. 232 * Return the pinned page if successful; otherwise, return NULL. 233 */ 234 static vm_page_t 235 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 236 { 237 vm_page_t m, ma[1]; 238 vm_pindex_t pindex; 239 int rv; 240 241 VM_OBJECT_LOCK(object); 242 pindex = OFF_TO_IDX(offset); 243 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 244 if (m->valid != VM_PAGE_BITS_ALL) { 245 ma[0] = m; 246 rv = vm_pager_get_pages(object, ma, 1, 0); 247 m = vm_page_lookup(object, pindex); 248 if (m == NULL) 249 goto out; 250 if (rv != VM_PAGER_OK) { 251 vm_page_lock(m); 252 vm_page_free(m); 253 vm_page_unlock(m); 254 m = NULL; 255 goto out; 256 } 257 } 258 vm_page_lock(m); 259 vm_page_hold(m); 260 vm_page_unlock(m); 261 vm_page_wakeup(m); 262 out: 263 VM_OBJECT_UNLOCK(object); 264 return (m); 265 } 266 267 /* 268 * Return a CPU private mapping to the page at the given offset within the 269 * given object. The page is pinned before it is mapped. 270 */ 271 struct sf_buf * 272 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 273 { 274 vm_page_t m; 275 276 m = vm_imgact_hold_page(object, offset); 277 if (m == NULL) 278 return (NULL); 279 sched_pin(); 280 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 281 } 282 283 /* 284 * Destroy the given CPU private mapping and unpin the page that it mapped. 285 */ 286 void 287 vm_imgact_unmap_page(struct sf_buf *sf) 288 { 289 vm_page_t m; 290 291 m = sf_buf_page(sf); 292 sf_buf_free(sf); 293 sched_unpin(); 294 vm_page_lock(m); 295 vm_page_unhold(m); 296 vm_page_unlock(m); 297 } 298 299 void 300 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz) 301 { 302 303 pmap_sync_icache(map->pmap, va, sz); 304 } 305 306 struct kstack_cache_entry *kstack_cache; 307 static int kstack_cache_size = 128; 308 static int kstacks; 309 static struct mtx kstack_cache_mtx; 310 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 311 ""); 312 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 313 ""); 314 315 #ifndef KSTACK_MAX_PAGES 316 #define KSTACK_MAX_PAGES 32 317 #endif 318 319 /* 320 * Create the kernel stack (including pcb for i386) for a new thread. 321 * This routine directly affects the fork perf for a process and 322 * create performance for a thread. 323 */ 324 int 325 vm_thread_new(struct thread *td, int pages) 326 { 327 vm_object_t ksobj; 328 vm_offset_t ks; 329 vm_page_t m, ma[KSTACK_MAX_PAGES]; 330 struct kstack_cache_entry *ks_ce; 331 int i; 332 333 /* Bounds check */ 334 if (pages <= 1) 335 pages = KSTACK_PAGES; 336 else if (pages > KSTACK_MAX_PAGES) 337 pages = KSTACK_MAX_PAGES; 338 339 if (pages == KSTACK_PAGES) { 340 mtx_lock(&kstack_cache_mtx); 341 if (kstack_cache != NULL) { 342 ks_ce = kstack_cache; 343 kstack_cache = ks_ce->next_ks_entry; 344 mtx_unlock(&kstack_cache_mtx); 345 346 td->td_kstack_obj = ks_ce->ksobj; 347 td->td_kstack = (vm_offset_t)ks_ce; 348 td->td_kstack_pages = KSTACK_PAGES; 349 return (1); 350 } 351 mtx_unlock(&kstack_cache_mtx); 352 } 353 354 /* 355 * Allocate an object for the kstack. 356 */ 357 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 358 359 /* 360 * Get a kernel virtual address for this thread's kstack. 361 */ 362 #if defined(__mips__) 363 /* 364 * We need to align the kstack's mapped address to fit within 365 * a single TLB entry. 366 */ 367 ks = kmem_alloc_nofault_space(kernel_map, 368 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE, VMFS_TLB_ALIGNED_SPACE); 369 #else 370 ks = kmem_alloc_nofault(kernel_map, 371 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 372 #endif 373 if (ks == 0) { 374 printf("vm_thread_new: kstack allocation failed\n"); 375 vm_object_deallocate(ksobj); 376 return (0); 377 } 378 379 atomic_add_int(&kstacks, 1); 380 if (KSTACK_GUARD_PAGES != 0) { 381 pmap_qremove(ks, KSTACK_GUARD_PAGES); 382 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 383 } 384 td->td_kstack_obj = ksobj; 385 td->td_kstack = ks; 386 /* 387 * Knowing the number of pages allocated is useful when you 388 * want to deallocate them. 389 */ 390 td->td_kstack_pages = pages; 391 /* 392 * For the length of the stack, link in a real page of ram for each 393 * page of stack. 394 */ 395 VM_OBJECT_LOCK(ksobj); 396 for (i = 0; i < pages; i++) { 397 /* 398 * Get a kernel stack page. 399 */ 400 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 401 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 402 ma[i] = m; 403 m->valid = VM_PAGE_BITS_ALL; 404 } 405 VM_OBJECT_UNLOCK(ksobj); 406 pmap_qenter(ks, ma, pages); 407 return (1); 408 } 409 410 static void 411 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 412 { 413 vm_page_t m; 414 int i; 415 416 atomic_add_int(&kstacks, -1); 417 pmap_qremove(ks, pages); 418 VM_OBJECT_LOCK(ksobj); 419 for (i = 0; i < pages; i++) { 420 m = vm_page_lookup(ksobj, i); 421 if (m == NULL) 422 panic("vm_thread_dispose: kstack already missing?"); 423 vm_page_lock(m); 424 vm_page_unwire(m, 0); 425 vm_page_free(m); 426 vm_page_unlock(m); 427 } 428 VM_OBJECT_UNLOCK(ksobj); 429 vm_object_deallocate(ksobj); 430 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 431 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 432 } 433 434 /* 435 * Dispose of a thread's kernel stack. 436 */ 437 void 438 vm_thread_dispose(struct thread *td) 439 { 440 vm_object_t ksobj; 441 vm_offset_t ks; 442 struct kstack_cache_entry *ks_ce; 443 int pages; 444 445 pages = td->td_kstack_pages; 446 ksobj = td->td_kstack_obj; 447 ks = td->td_kstack; 448 td->td_kstack = 0; 449 td->td_kstack_pages = 0; 450 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 451 ks_ce = (struct kstack_cache_entry *)ks; 452 ks_ce->ksobj = ksobj; 453 mtx_lock(&kstack_cache_mtx); 454 ks_ce->next_ks_entry = kstack_cache; 455 kstack_cache = ks_ce; 456 mtx_unlock(&kstack_cache_mtx); 457 return; 458 } 459 vm_thread_stack_dispose(ksobj, ks, pages); 460 } 461 462 static void 463 vm_thread_stack_lowmem(void *nulll) 464 { 465 struct kstack_cache_entry *ks_ce, *ks_ce1; 466 467 mtx_lock(&kstack_cache_mtx); 468 ks_ce = kstack_cache; 469 kstack_cache = NULL; 470 mtx_unlock(&kstack_cache_mtx); 471 472 while (ks_ce != NULL) { 473 ks_ce1 = ks_ce; 474 ks_ce = ks_ce->next_ks_entry; 475 476 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 477 KSTACK_PAGES); 478 } 479 } 480 481 static void 482 kstack_cache_init(void *nulll) 483 { 484 485 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 486 EVENTHANDLER_PRI_ANY); 487 } 488 489 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 490 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 491 492 #ifndef NO_SWAPPING 493 /* 494 * Allow a thread's kernel stack to be paged out. 495 */ 496 static void 497 vm_thread_swapout(struct thread *td) 498 { 499 vm_object_t ksobj; 500 vm_page_t m; 501 int i, pages; 502 503 cpu_thread_swapout(td); 504 pages = td->td_kstack_pages; 505 ksobj = td->td_kstack_obj; 506 pmap_qremove(td->td_kstack, pages); 507 VM_OBJECT_LOCK(ksobj); 508 for (i = 0; i < pages; i++) { 509 m = vm_page_lookup(ksobj, i); 510 if (m == NULL) 511 panic("vm_thread_swapout: kstack already missing?"); 512 vm_page_dirty(m); 513 vm_page_lock(m); 514 vm_page_unwire(m, 0); 515 vm_page_unlock(m); 516 } 517 VM_OBJECT_UNLOCK(ksobj); 518 } 519 520 /* 521 * Bring the kernel stack for a specified thread back in. 522 */ 523 static void 524 vm_thread_swapin(struct thread *td) 525 { 526 vm_object_t ksobj; 527 vm_page_t ma[KSTACK_MAX_PAGES]; 528 int i, j, k, pages, rv; 529 530 pages = td->td_kstack_pages; 531 ksobj = td->td_kstack_obj; 532 VM_OBJECT_LOCK(ksobj); 533 for (i = 0; i < pages; i++) 534 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY | 535 VM_ALLOC_WIRED); 536 for (i = 0; i < pages; i++) { 537 if (ma[i]->valid != VM_PAGE_BITS_ALL) { 538 KASSERT(ma[i]->oflags & VPO_BUSY, 539 ("lost busy 1")); 540 vm_object_pip_add(ksobj, 1); 541 for (j = i + 1; j < pages; j++) { 542 KASSERT(ma[j]->valid == VM_PAGE_BITS_ALL || 543 (ma[j]->oflags & VPO_BUSY), 544 ("lost busy 2")); 545 if (ma[j]->valid == VM_PAGE_BITS_ALL) 546 break; 547 } 548 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0); 549 if (rv != VM_PAGER_OK) 550 panic("vm_thread_swapin: cannot get kstack for proc: %d", 551 td->td_proc->p_pid); 552 vm_object_pip_wakeup(ksobj); 553 for (k = i; k < j; k++) 554 ma[k] = vm_page_lookup(ksobj, k); 555 vm_page_wakeup(ma[i]); 556 } else if (ma[i]->oflags & VPO_BUSY) 557 vm_page_wakeup(ma[i]); 558 } 559 VM_OBJECT_UNLOCK(ksobj); 560 pmap_qenter(td->td_kstack, ma, pages); 561 cpu_thread_swapin(td); 562 } 563 #endif /* !NO_SWAPPING */ 564 565 /* 566 * Implement fork's actions on an address space. 567 * Here we arrange for the address space to be copied or referenced, 568 * allocate a user struct (pcb and kernel stack), then call the 569 * machine-dependent layer to fill those in and make the new process 570 * ready to run. The new process is set up so that it returns directly 571 * to user mode to avoid stack copying and relocation problems. 572 */ 573 int 574 vm_forkproc(td, p2, td2, vm2, flags) 575 struct thread *td; 576 struct proc *p2; 577 struct thread *td2; 578 struct vmspace *vm2; 579 int flags; 580 { 581 struct proc *p1 = td->td_proc; 582 int error; 583 584 if ((flags & RFPROC) == 0) { 585 /* 586 * Divorce the memory, if it is shared, essentially 587 * this changes shared memory amongst threads, into 588 * COW locally. 589 */ 590 if ((flags & RFMEM) == 0) { 591 if (p1->p_vmspace->vm_refcnt > 1) { 592 error = vmspace_unshare(p1); 593 if (error) 594 return (error); 595 } 596 } 597 cpu_fork(td, p2, td2, flags); 598 return (0); 599 } 600 601 if (flags & RFMEM) { 602 p2->p_vmspace = p1->p_vmspace; 603 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 604 } 605 606 while (vm_page_count_severe()) { 607 VM_WAIT; 608 } 609 610 if ((flags & RFMEM) == 0) { 611 p2->p_vmspace = vm2; 612 if (p1->p_vmspace->vm_shm) 613 shmfork(p1, p2); 614 } 615 616 /* 617 * cpu_fork will copy and update the pcb, set up the kernel stack, 618 * and make the child ready to run. 619 */ 620 cpu_fork(td, p2, td2, flags); 621 return (0); 622 } 623 624 /* 625 * Called after process has been wait(2)'ed apon and is being reaped. 626 * The idea is to reclaim resources that we could not reclaim while 627 * the process was still executing. 628 */ 629 void 630 vm_waitproc(p) 631 struct proc *p; 632 { 633 634 vmspace_exitfree(p); /* and clean-out the vmspace */ 635 } 636 637 void 638 faultin(p) 639 struct proc *p; 640 { 641 #ifdef NO_SWAPPING 642 643 PROC_LOCK_ASSERT(p, MA_OWNED); 644 if ((p->p_flag & P_INMEM) == 0) 645 panic("faultin: proc swapped out with NO_SWAPPING!"); 646 #else /* !NO_SWAPPING */ 647 struct thread *td; 648 649 PROC_LOCK_ASSERT(p, MA_OWNED); 650 /* 651 * If another process is swapping in this process, 652 * just wait until it finishes. 653 */ 654 if (p->p_flag & P_SWAPPINGIN) { 655 while (p->p_flag & P_SWAPPINGIN) 656 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 657 return; 658 } 659 if ((p->p_flag & P_INMEM) == 0) { 660 /* 661 * Don't let another thread swap process p out while we are 662 * busy swapping it in. 663 */ 664 ++p->p_lock; 665 p->p_flag |= P_SWAPPINGIN; 666 PROC_UNLOCK(p); 667 668 /* 669 * We hold no lock here because the list of threads 670 * can not change while all threads in the process are 671 * swapped out. 672 */ 673 FOREACH_THREAD_IN_PROC(p, td) 674 vm_thread_swapin(td); 675 PROC_LOCK(p); 676 swapclear(p); 677 p->p_swtick = ticks; 678 679 wakeup(&p->p_flag); 680 681 /* Allow other threads to swap p out now. */ 682 --p->p_lock; 683 } 684 #endif /* NO_SWAPPING */ 685 } 686 687 /* 688 * This swapin algorithm attempts to swap-in processes only if there 689 * is enough space for them. Of course, if a process waits for a long 690 * time, it will be swapped in anyway. 691 * 692 * Giant is held on entry. 693 */ 694 /* ARGSUSED*/ 695 static void 696 scheduler(dummy) 697 void *dummy; 698 { 699 struct proc *p; 700 struct thread *td; 701 struct proc *pp; 702 int slptime; 703 int swtime; 704 int ppri; 705 int pri; 706 707 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 708 mtx_unlock(&Giant); 709 710 loop: 711 if (vm_page_count_min()) { 712 VM_WAIT; 713 goto loop; 714 } 715 716 pp = NULL; 717 ppri = INT_MIN; 718 sx_slock(&allproc_lock); 719 FOREACH_PROC_IN_SYSTEM(p) { 720 PROC_LOCK(p); 721 if (p->p_state == PRS_NEW || 722 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 723 PROC_UNLOCK(p); 724 continue; 725 } 726 swtime = (ticks - p->p_swtick) / hz; 727 FOREACH_THREAD_IN_PROC(p, td) { 728 /* 729 * An otherwise runnable thread of a process 730 * swapped out has only the TDI_SWAPPED bit set. 731 * 732 */ 733 thread_lock(td); 734 if (td->td_inhibitors == TDI_SWAPPED) { 735 slptime = (ticks - td->td_slptick) / hz; 736 pri = swtime + slptime; 737 if ((td->td_flags & TDF_SWAPINREQ) == 0) 738 pri -= p->p_nice * 8; 739 /* 740 * if this thread is higher priority 741 * and there is enough space, then select 742 * this process instead of the previous 743 * selection. 744 */ 745 if (pri > ppri) { 746 pp = p; 747 ppri = pri; 748 } 749 } 750 thread_unlock(td); 751 } 752 PROC_UNLOCK(p); 753 } 754 sx_sunlock(&allproc_lock); 755 756 /* 757 * Nothing to do, back to sleep. 758 */ 759 if ((p = pp) == NULL) { 760 tsleep(&proc0, PVM, "sched", MAXSLP * hz / 2); 761 goto loop; 762 } 763 PROC_LOCK(p); 764 765 /* 766 * Another process may be bringing or may have already 767 * brought this process in while we traverse all threads. 768 * Or, this process may even be being swapped out again. 769 */ 770 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 771 PROC_UNLOCK(p); 772 goto loop; 773 } 774 775 /* 776 * We would like to bring someone in. (only if there is space). 777 * [What checks the space? ] 778 */ 779 faultin(p); 780 PROC_UNLOCK(p); 781 goto loop; 782 } 783 784 void 785 kick_proc0(void) 786 { 787 788 wakeup(&proc0); 789 } 790 791 #ifndef NO_SWAPPING 792 793 /* 794 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 795 */ 796 static int swap_idle_threshold1 = 2; 797 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 798 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 799 800 /* 801 * Swap_idle_threshold2 is the time that a process can be idle before 802 * it will be swapped out, if idle swapping is enabled. 803 */ 804 static int swap_idle_threshold2 = 10; 805 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 806 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 807 808 /* 809 * First, if any processes have been sleeping or stopped for at least 810 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 811 * no such processes exist, then the longest-sleeping or stopped 812 * process is swapped out. Finally, and only as a last resort, if 813 * there are no sleeping or stopped processes, the longest-resident 814 * process is swapped out. 815 */ 816 void 817 swapout_procs(action) 818 int action; 819 { 820 struct proc *p; 821 struct thread *td; 822 int didswap = 0; 823 824 retry: 825 sx_slock(&allproc_lock); 826 FOREACH_PROC_IN_SYSTEM(p) { 827 struct vmspace *vm; 828 int minslptime = 100000; 829 int slptime; 830 831 /* 832 * Watch out for a process in 833 * creation. It may have no 834 * address space or lock yet. 835 */ 836 if (p->p_state == PRS_NEW) 837 continue; 838 /* 839 * An aio daemon switches its 840 * address space while running. 841 * Perform a quick check whether 842 * a process has P_SYSTEM. 843 */ 844 if ((p->p_flag & P_SYSTEM) != 0) 845 continue; 846 /* 847 * Do not swapout a process that 848 * is waiting for VM data 849 * structures as there is a possible 850 * deadlock. Test this first as 851 * this may block. 852 * 853 * Lock the map until swapout 854 * finishes, or a thread of this 855 * process may attempt to alter 856 * the map. 857 */ 858 vm = vmspace_acquire_ref(p); 859 if (vm == NULL) 860 continue; 861 if (!vm_map_trylock(&vm->vm_map)) 862 goto nextproc1; 863 864 PROC_LOCK(p); 865 if (p->p_lock != 0 || 866 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 867 ) != 0) { 868 goto nextproc; 869 } 870 /* 871 * only aiod changes vmspace, however it will be 872 * skipped because of the if statement above checking 873 * for P_SYSTEM 874 */ 875 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 876 goto nextproc; 877 878 switch (p->p_state) { 879 default: 880 /* Don't swap out processes in any sort 881 * of 'special' state. */ 882 break; 883 884 case PRS_NORMAL: 885 /* 886 * do not swapout a realtime process 887 * Check all the thread groups.. 888 */ 889 FOREACH_THREAD_IN_PROC(p, td) { 890 thread_lock(td); 891 if (PRI_IS_REALTIME(td->td_pri_class)) { 892 thread_unlock(td); 893 goto nextproc; 894 } 895 slptime = (ticks - td->td_slptick) / hz; 896 /* 897 * Guarantee swap_idle_threshold1 898 * time in memory. 899 */ 900 if (slptime < swap_idle_threshold1) { 901 thread_unlock(td); 902 goto nextproc; 903 } 904 905 /* 906 * Do not swapout a process if it is 907 * waiting on a critical event of some 908 * kind or there is a thread whose 909 * pageable memory may be accessed. 910 * 911 * This could be refined to support 912 * swapping out a thread. 913 */ 914 if (!thread_safetoswapout(td)) { 915 thread_unlock(td); 916 goto nextproc; 917 } 918 /* 919 * If the system is under memory stress, 920 * or if we are swapping 921 * idle processes >= swap_idle_threshold2, 922 * then swap the process out. 923 */ 924 if (((action & VM_SWAP_NORMAL) == 0) && 925 (((action & VM_SWAP_IDLE) == 0) || 926 (slptime < swap_idle_threshold2))) { 927 thread_unlock(td); 928 goto nextproc; 929 } 930 931 if (minslptime > slptime) 932 minslptime = slptime; 933 thread_unlock(td); 934 } 935 936 /* 937 * If the pageout daemon didn't free enough pages, 938 * or if this process is idle and the system is 939 * configured to swap proactively, swap it out. 940 */ 941 if ((action & VM_SWAP_NORMAL) || 942 ((action & VM_SWAP_IDLE) && 943 (minslptime > swap_idle_threshold2))) { 944 if (swapout(p) == 0) 945 didswap++; 946 PROC_UNLOCK(p); 947 vm_map_unlock(&vm->vm_map); 948 vmspace_free(vm); 949 sx_sunlock(&allproc_lock); 950 goto retry; 951 } 952 } 953 nextproc: 954 PROC_UNLOCK(p); 955 vm_map_unlock(&vm->vm_map); 956 nextproc1: 957 vmspace_free(vm); 958 continue; 959 } 960 sx_sunlock(&allproc_lock); 961 /* 962 * If we swapped something out, and another process needed memory, 963 * then wakeup the sched process. 964 */ 965 if (didswap) 966 wakeup(&proc0); 967 } 968 969 static void 970 swapclear(p) 971 struct proc *p; 972 { 973 struct thread *td; 974 975 PROC_LOCK_ASSERT(p, MA_OWNED); 976 977 FOREACH_THREAD_IN_PROC(p, td) { 978 thread_lock(td); 979 td->td_flags |= TDF_INMEM; 980 td->td_flags &= ~TDF_SWAPINREQ; 981 TD_CLR_SWAPPED(td); 982 if (TD_CAN_RUN(td)) 983 if (setrunnable(td)) { 984 #ifdef INVARIANTS 985 /* 986 * XXX: We just cleared TDI_SWAPPED 987 * above and set TDF_INMEM, so this 988 * should never happen. 989 */ 990 panic("not waking up swapper"); 991 #endif 992 } 993 thread_unlock(td); 994 } 995 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 996 p->p_flag |= P_INMEM; 997 } 998 999 static int 1000 swapout(p) 1001 struct proc *p; 1002 { 1003 struct thread *td; 1004 1005 PROC_LOCK_ASSERT(p, MA_OWNED); 1006 #if defined(SWAP_DEBUG) 1007 printf("swapping out %d\n", p->p_pid); 1008 #endif 1009 1010 /* 1011 * The states of this process and its threads may have changed 1012 * by now. Assuming that there is only one pageout daemon thread, 1013 * this process should still be in memory. 1014 */ 1015 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1016 ("swapout: lost a swapout race?")); 1017 1018 /* 1019 * remember the process resident count 1020 */ 1021 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1022 /* 1023 * Check and mark all threads before we proceed. 1024 */ 1025 p->p_flag &= ~P_INMEM; 1026 p->p_flag |= P_SWAPPINGOUT; 1027 FOREACH_THREAD_IN_PROC(p, td) { 1028 thread_lock(td); 1029 if (!thread_safetoswapout(td)) { 1030 thread_unlock(td); 1031 swapclear(p); 1032 return (EBUSY); 1033 } 1034 td->td_flags &= ~TDF_INMEM; 1035 TD_SET_SWAPPED(td); 1036 thread_unlock(td); 1037 } 1038 td = FIRST_THREAD_IN_PROC(p); 1039 ++td->td_ru.ru_nswap; 1040 PROC_UNLOCK(p); 1041 1042 /* 1043 * This list is stable because all threads are now prevented from 1044 * running. The list is only modified in the context of a running 1045 * thread in this process. 1046 */ 1047 FOREACH_THREAD_IN_PROC(p, td) 1048 vm_thread_swapout(td); 1049 1050 PROC_LOCK(p); 1051 p->p_flag &= ~P_SWAPPINGOUT; 1052 p->p_swtick = ticks; 1053 return (0); 1054 } 1055 #endif /* !NO_SWAPPING */
Cache object: 7cc1db8764631d0fcc02fcd0fbd9ec55
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