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("$FreeBSD$"); 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/rwlock.h> 75 #include <sys/sched.h> 76 #include <sys/sf_buf.h> 77 #include <sys/shm.h> 78 #include <sys/vmmeter.h> 79 #include <sys/sx.h> 80 #include <sys/sysctl.h> 81 #include <sys/_kstack_cache.h> 82 #include <sys/eventhandler.h> 83 #include <sys/kernel.h> 84 #include <sys/ktr.h> 85 #include <sys/unistd.h> 86 87 #include <vm/vm.h> 88 #include <vm/vm_param.h> 89 #include <vm/pmap.h> 90 #include <vm/vm_map.h> 91 #include <vm/vm_page.h> 92 #include <vm/vm_pageout.h> 93 #include <vm/vm_object.h> 94 #include <vm/vm_kern.h> 95 #include <vm/vm_extern.h> 96 #include <vm/vm_pager.h> 97 #include <vm/swap_pager.h> 98 99 /* 100 * System initialization 101 * 102 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 103 * 104 * Note: run scheduling should be divorced from the vm system. 105 */ 106 static void scheduler(void *); 107 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL); 108 109 #ifndef NO_SWAPPING 110 static int swapout(struct proc *); 111 static void swapclear(struct proc *); 112 static void vm_thread_swapin(struct thread *td); 113 static void vm_thread_swapout(struct thread *td); 114 #endif 115 116 /* 117 * MPSAFE 118 * 119 * WARNING! This code calls vm_map_check_protection() which only checks 120 * the associated vm_map_entry range. It does not determine whether the 121 * contents of the memory is actually readable or writable. In most cases 122 * just checking the vm_map_entry is sufficient within the kernel's address 123 * space. 124 */ 125 int 126 kernacc(addr, len, rw) 127 void *addr; 128 int len, rw; 129 { 130 boolean_t rv; 131 vm_offset_t saddr, eaddr; 132 vm_prot_t prot; 133 134 KASSERT((rw & ~VM_PROT_ALL) == 0, 135 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 136 137 if ((vm_offset_t)addr + len > kernel_map->max_offset || 138 (vm_offset_t)addr + len < (vm_offset_t)addr) 139 return (FALSE); 140 141 prot = rw; 142 saddr = trunc_page((vm_offset_t)addr); 143 eaddr = round_page((vm_offset_t)addr + len); 144 vm_map_lock_read(kernel_map); 145 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 146 vm_map_unlock_read(kernel_map); 147 return (rv == TRUE); 148 } 149 150 /* 151 * MPSAFE 152 * 153 * WARNING! This code calls vm_map_check_protection() which only checks 154 * the associated vm_map_entry range. It does not determine whether the 155 * contents of the memory is actually readable or writable. vmapbuf(), 156 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 157 * used in conjuction with this call. 158 */ 159 int 160 useracc(addr, len, rw) 161 void *addr; 162 int len, rw; 163 { 164 boolean_t rv; 165 vm_prot_t prot; 166 vm_map_t map; 167 168 KASSERT((rw & ~VM_PROT_ALL) == 0, 169 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 170 prot = rw; 171 map = &curproc->p_vmspace->vm_map; 172 if ((vm_offset_t)addr + len > vm_map_max(map) || 173 (vm_offset_t)addr + len < (vm_offset_t)addr) { 174 return (FALSE); 175 } 176 vm_map_lock_read(map); 177 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 178 round_page((vm_offset_t)addr + len), prot); 179 vm_map_unlock_read(map); 180 return (rv == TRUE); 181 } 182 183 int 184 vslock(void *addr, size_t len) 185 { 186 vm_offset_t end, last, start; 187 vm_size_t npages; 188 int error; 189 190 last = (vm_offset_t)addr + len; 191 start = trunc_page((vm_offset_t)addr); 192 end = round_page(last); 193 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 194 return (EINVAL); 195 npages = atop(end - start); 196 if (npages > vm_page_max_wired) 197 return (ENOMEM); 198 #if 0 199 /* 200 * XXX - not yet 201 * 202 * The limit for transient usage of wired pages should be 203 * larger than for "permanent" wired pages (mlock()). 204 * 205 * Also, the sysctl code, which is the only present user 206 * of vslock(), does a hard loop on EAGAIN. 207 */ 208 if (npages + cnt.v_wire_count > vm_page_max_wired) 209 return (EAGAIN); 210 #endif 211 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 212 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 213 /* 214 * Return EFAULT on error to match copy{in,out}() behaviour 215 * rather than returning ENOMEM like mlock() would. 216 */ 217 return (error == KERN_SUCCESS ? 0 : EFAULT); 218 } 219 220 void 221 vsunlock(void *addr, size_t len) 222 { 223 224 /* Rely on the parameter sanity checks performed by vslock(). */ 225 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 226 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 227 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 228 } 229 230 /* 231 * Pin the page contained within the given object at the given offset. If the 232 * page is not resident, allocate and load it using the given object's pager. 233 * Return the pinned page if successful; otherwise, return NULL. 234 */ 235 static vm_page_t 236 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 237 { 238 vm_page_t m, ma[1]; 239 vm_pindex_t pindex; 240 int rv; 241 242 VM_OBJECT_WLOCK(object); 243 pindex = OFF_TO_IDX(offset); 244 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY | 245 VM_ALLOC_NOBUSY); 246 if (m->valid != VM_PAGE_BITS_ALL) { 247 vm_page_busy(m); 248 ma[0] = m; 249 rv = vm_pager_get_pages(object, ma, 1, 0); 250 m = vm_page_lookup(object, pindex); 251 if (m == NULL) 252 goto out; 253 if (rv != VM_PAGER_OK) { 254 vm_page_lock(m); 255 vm_page_free(m); 256 vm_page_unlock(m); 257 m = NULL; 258 goto out; 259 } 260 vm_page_wakeup(m); 261 } 262 vm_page_lock(m); 263 vm_page_hold(m); 264 vm_page_unlock(m); 265 out: 266 VM_OBJECT_WUNLOCK(object); 267 return (m); 268 } 269 270 /* 271 * Return a CPU private mapping to the page at the given offset within the 272 * given object. The page is pinned before it is mapped. 273 */ 274 struct sf_buf * 275 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 276 { 277 vm_page_t m; 278 279 m = vm_imgact_hold_page(object, offset); 280 if (m == NULL) 281 return (NULL); 282 sched_pin(); 283 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 284 } 285 286 /* 287 * Destroy the given CPU private mapping and unpin the page that it mapped. 288 */ 289 void 290 vm_imgact_unmap_page(struct sf_buf *sf) 291 { 292 vm_page_t m; 293 294 m = sf_buf_page(sf); 295 sf_buf_free(sf); 296 sched_unpin(); 297 vm_page_lock(m); 298 vm_page_unhold(m); 299 vm_page_unlock(m); 300 } 301 302 void 303 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz) 304 { 305 306 pmap_sync_icache(map->pmap, va, sz); 307 } 308 309 struct kstack_cache_entry *kstack_cache; 310 static int kstack_cache_size = 128; 311 static int kstacks; 312 static struct mtx kstack_cache_mtx; 313 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 314 315 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 316 ""); 317 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 318 ""); 319 320 #ifndef KSTACK_MAX_PAGES 321 #define KSTACK_MAX_PAGES 32 322 #endif 323 324 /* 325 * Create the kernel stack (including pcb for i386) for a new thread. 326 * This routine directly affects the fork perf for a process and 327 * create performance for a thread. 328 */ 329 int 330 vm_thread_new(struct thread *td, int pages) 331 { 332 vm_object_t ksobj; 333 vm_offset_t ks; 334 vm_page_t m, ma[KSTACK_MAX_PAGES]; 335 struct kstack_cache_entry *ks_ce; 336 int i; 337 338 /* Bounds check */ 339 if (pages <= 1) 340 pages = KSTACK_PAGES; 341 else if (pages > KSTACK_MAX_PAGES) 342 pages = KSTACK_MAX_PAGES; 343 344 if (pages == KSTACK_PAGES) { 345 mtx_lock(&kstack_cache_mtx); 346 if (kstack_cache != NULL) { 347 ks_ce = kstack_cache; 348 kstack_cache = ks_ce->next_ks_entry; 349 mtx_unlock(&kstack_cache_mtx); 350 351 td->td_kstack_obj = ks_ce->ksobj; 352 td->td_kstack = (vm_offset_t)ks_ce; 353 td->td_kstack_pages = KSTACK_PAGES; 354 return (1); 355 } 356 mtx_unlock(&kstack_cache_mtx); 357 } 358 359 /* 360 * Allocate an object for the kstack. 361 */ 362 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 363 364 /* 365 * Get a kernel virtual address for this thread's kstack. 366 */ 367 #if defined(__mips__) 368 /* 369 * We need to align the kstack's mapped address to fit within 370 * a single TLB entry. 371 */ 372 ks = kmem_alloc_nofault_space(kernel_map, 373 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE, VMFS_TLB_ALIGNED_SPACE); 374 #else 375 ks = kmem_alloc_nofault(kernel_map, 376 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 377 #endif 378 if (ks == 0) { 379 printf("vm_thread_new: kstack allocation failed\n"); 380 vm_object_deallocate(ksobj); 381 return (0); 382 } 383 384 atomic_add_int(&kstacks, 1); 385 if (KSTACK_GUARD_PAGES != 0) { 386 pmap_qremove(ks, KSTACK_GUARD_PAGES); 387 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 388 } 389 td->td_kstack_obj = ksobj; 390 td->td_kstack = ks; 391 /* 392 * Knowing the number of pages allocated is useful when you 393 * want to deallocate them. 394 */ 395 td->td_kstack_pages = pages; 396 /* 397 * For the length of the stack, link in a real page of ram for each 398 * page of stack. 399 */ 400 VM_OBJECT_WLOCK(ksobj); 401 for (i = 0; i < pages; i++) { 402 /* 403 * Get a kernel stack page. 404 */ 405 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 406 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 407 ma[i] = m; 408 m->valid = VM_PAGE_BITS_ALL; 409 } 410 VM_OBJECT_WUNLOCK(ksobj); 411 pmap_qenter(ks, ma, pages); 412 return (1); 413 } 414 415 static void 416 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 417 { 418 vm_page_t m; 419 int i; 420 421 atomic_add_int(&kstacks, -1); 422 pmap_qremove(ks, pages); 423 VM_OBJECT_WLOCK(ksobj); 424 for (i = 0; i < pages; i++) { 425 m = vm_page_lookup(ksobj, i); 426 if (m == NULL) 427 panic("vm_thread_dispose: kstack already missing?"); 428 vm_page_lock(m); 429 vm_page_unwire(m, 0); 430 vm_page_free(m); 431 vm_page_unlock(m); 432 } 433 VM_OBJECT_WUNLOCK(ksobj); 434 vm_object_deallocate(ksobj); 435 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 436 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 437 } 438 439 /* 440 * Dispose of a thread's kernel stack. 441 */ 442 void 443 vm_thread_dispose(struct thread *td) 444 { 445 vm_object_t ksobj; 446 vm_offset_t ks; 447 struct kstack_cache_entry *ks_ce; 448 int pages; 449 450 pages = td->td_kstack_pages; 451 ksobj = td->td_kstack_obj; 452 ks = td->td_kstack; 453 td->td_kstack = 0; 454 td->td_kstack_pages = 0; 455 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 456 ks_ce = (struct kstack_cache_entry *)ks; 457 ks_ce->ksobj = ksobj; 458 mtx_lock(&kstack_cache_mtx); 459 ks_ce->next_ks_entry = kstack_cache; 460 kstack_cache = ks_ce; 461 mtx_unlock(&kstack_cache_mtx); 462 return; 463 } 464 vm_thread_stack_dispose(ksobj, ks, pages); 465 } 466 467 static void 468 vm_thread_stack_lowmem(void *nulll) 469 { 470 struct kstack_cache_entry *ks_ce, *ks_ce1; 471 472 mtx_lock(&kstack_cache_mtx); 473 ks_ce = kstack_cache; 474 kstack_cache = NULL; 475 mtx_unlock(&kstack_cache_mtx); 476 477 while (ks_ce != NULL) { 478 ks_ce1 = ks_ce; 479 ks_ce = ks_ce->next_ks_entry; 480 481 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 482 KSTACK_PAGES); 483 } 484 } 485 486 static void 487 kstack_cache_init(void *nulll) 488 { 489 490 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 491 EVENTHANDLER_PRI_ANY); 492 } 493 494 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 495 496 #ifndef NO_SWAPPING 497 /* 498 * Allow a thread's kernel stack to be paged out. 499 */ 500 static void 501 vm_thread_swapout(struct thread *td) 502 { 503 vm_object_t ksobj; 504 vm_page_t m; 505 int i, pages; 506 507 cpu_thread_swapout(td); 508 pages = td->td_kstack_pages; 509 ksobj = td->td_kstack_obj; 510 pmap_qremove(td->td_kstack, pages); 511 VM_OBJECT_WLOCK(ksobj); 512 for (i = 0; i < pages; i++) { 513 m = vm_page_lookup(ksobj, i); 514 if (m == NULL) 515 panic("vm_thread_swapout: kstack already missing?"); 516 vm_page_dirty(m); 517 vm_page_lock(m); 518 vm_page_unwire(m, 0); 519 vm_page_unlock(m); 520 } 521 VM_OBJECT_WUNLOCK(ksobj); 522 } 523 524 /* 525 * Bring the kernel stack for a specified thread back in. 526 */ 527 static void 528 vm_thread_swapin(struct thread *td) 529 { 530 vm_object_t ksobj; 531 vm_page_t ma[KSTACK_MAX_PAGES]; 532 int i, j, k, pages, rv; 533 534 pages = td->td_kstack_pages; 535 ksobj = td->td_kstack_obj; 536 VM_OBJECT_WLOCK(ksobj); 537 for (i = 0; i < pages; i++) 538 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY | 539 VM_ALLOC_WIRED); 540 for (i = 0; i < pages; i++) { 541 if (ma[i]->valid != VM_PAGE_BITS_ALL) { 542 KASSERT(ma[i]->oflags & VPO_BUSY, 543 ("lost busy 1")); 544 vm_object_pip_add(ksobj, 1); 545 for (j = i + 1; j < pages; j++) { 546 KASSERT(ma[j]->valid == VM_PAGE_BITS_ALL || 547 (ma[j]->oflags & VPO_BUSY), 548 ("lost busy 2")); 549 if (ma[j]->valid == VM_PAGE_BITS_ALL) 550 break; 551 } 552 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0); 553 if (rv != VM_PAGER_OK) 554 panic("vm_thread_swapin: cannot get kstack for proc: %d", 555 td->td_proc->p_pid); 556 vm_object_pip_wakeup(ksobj); 557 for (k = i; k < j; k++) 558 ma[k] = vm_page_lookup(ksobj, k); 559 vm_page_wakeup(ma[i]); 560 } else if (ma[i]->oflags & VPO_BUSY) 561 vm_page_wakeup(ma[i]); 562 } 563 VM_OBJECT_WUNLOCK(ksobj); 564 pmap_qenter(td->td_kstack, ma, pages); 565 cpu_thread_swapin(td); 566 } 567 #endif /* !NO_SWAPPING */ 568 569 /* 570 * Implement fork's actions on an address space. 571 * Here we arrange for the address space to be copied or referenced, 572 * allocate a user struct (pcb and kernel stack), then call the 573 * machine-dependent layer to fill those in and make the new process 574 * ready to run. The new process is set up so that it returns directly 575 * to user mode to avoid stack copying and relocation problems. 576 */ 577 int 578 vm_forkproc(td, p2, td2, vm2, flags) 579 struct thread *td; 580 struct proc *p2; 581 struct thread *td2; 582 struct vmspace *vm2; 583 int flags; 584 { 585 struct proc *p1 = td->td_proc; 586 int error; 587 588 if ((flags & RFPROC) == 0) { 589 /* 590 * Divorce the memory, if it is shared, essentially 591 * this changes shared memory amongst threads, into 592 * COW locally. 593 */ 594 if ((flags & RFMEM) == 0) { 595 if (p1->p_vmspace->vm_refcnt > 1) { 596 error = vmspace_unshare(p1); 597 if (error) 598 return (error); 599 } 600 } 601 cpu_fork(td, p2, td2, flags); 602 return (0); 603 } 604 605 if (flags & RFMEM) { 606 p2->p_vmspace = p1->p_vmspace; 607 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 608 } 609 610 while (vm_page_count_severe()) { 611 VM_WAIT; 612 } 613 614 if ((flags & RFMEM) == 0) { 615 p2->p_vmspace = vm2; 616 if (p1->p_vmspace->vm_shm) 617 shmfork(p1, p2); 618 } 619 620 /* 621 * cpu_fork will copy and update the pcb, set up the kernel stack, 622 * and make the child ready to run. 623 */ 624 cpu_fork(td, p2, td2, flags); 625 return (0); 626 } 627 628 /* 629 * Called after process has been wait(2)'ed apon and is being reaped. 630 * The idea is to reclaim resources that we could not reclaim while 631 * the process was still executing. 632 */ 633 void 634 vm_waitproc(p) 635 struct proc *p; 636 { 637 638 vmspace_exitfree(p); /* and clean-out the vmspace */ 639 } 640 641 void 642 faultin(p) 643 struct proc *p; 644 { 645 #ifdef NO_SWAPPING 646 647 PROC_LOCK_ASSERT(p, MA_OWNED); 648 if ((p->p_flag & P_INMEM) == 0) 649 panic("faultin: proc swapped out with NO_SWAPPING!"); 650 #else /* !NO_SWAPPING */ 651 struct thread *td; 652 653 PROC_LOCK_ASSERT(p, MA_OWNED); 654 /* 655 * If another process is swapping in this process, 656 * just wait until it finishes. 657 */ 658 if (p->p_flag & P_SWAPPINGIN) { 659 while (p->p_flag & P_SWAPPINGIN) 660 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 661 return; 662 } 663 if ((p->p_flag & P_INMEM) == 0) { 664 /* 665 * Don't let another thread swap process p out while we are 666 * busy swapping it in. 667 */ 668 ++p->p_lock; 669 p->p_flag |= P_SWAPPINGIN; 670 PROC_UNLOCK(p); 671 672 /* 673 * We hold no lock here because the list of threads 674 * can not change while all threads in the process are 675 * swapped out. 676 */ 677 FOREACH_THREAD_IN_PROC(p, td) 678 vm_thread_swapin(td); 679 PROC_LOCK(p); 680 swapclear(p); 681 p->p_swtick = ticks; 682 683 wakeup(&p->p_flag); 684 685 /* Allow other threads to swap p out now. */ 686 --p->p_lock; 687 } 688 #endif /* NO_SWAPPING */ 689 } 690 691 /* 692 * This swapin algorithm attempts to swap-in processes only if there 693 * is enough space for them. Of course, if a process waits for a long 694 * time, it will be swapped in anyway. 695 * 696 * Giant is held on entry. 697 */ 698 /* ARGSUSED*/ 699 static void 700 scheduler(dummy) 701 void *dummy; 702 { 703 struct proc *p; 704 struct thread *td; 705 struct proc *pp; 706 int slptime; 707 int swtime; 708 int ppri; 709 int pri; 710 711 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 712 mtx_unlock(&Giant); 713 714 loop: 715 if (vm_page_count_min()) { 716 VM_WAIT; 717 goto loop; 718 } 719 720 pp = NULL; 721 ppri = INT_MIN; 722 sx_slock(&allproc_lock); 723 FOREACH_PROC_IN_SYSTEM(p) { 724 PROC_LOCK(p); 725 if (p->p_state == PRS_NEW || 726 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 727 PROC_UNLOCK(p); 728 continue; 729 } 730 swtime = (ticks - p->p_swtick) / hz; 731 FOREACH_THREAD_IN_PROC(p, td) { 732 /* 733 * An otherwise runnable thread of a process 734 * swapped out has only the TDI_SWAPPED bit set. 735 * 736 */ 737 thread_lock(td); 738 if (td->td_inhibitors == TDI_SWAPPED) { 739 slptime = (ticks - td->td_slptick) / hz; 740 pri = swtime + slptime; 741 if ((td->td_flags & TDF_SWAPINREQ) == 0) 742 pri -= p->p_nice * 8; 743 /* 744 * if this thread is higher priority 745 * and there is enough space, then select 746 * this process instead of the previous 747 * selection. 748 */ 749 if (pri > ppri) { 750 pp = p; 751 ppri = pri; 752 } 753 } 754 thread_unlock(td); 755 } 756 PROC_UNLOCK(p); 757 } 758 sx_sunlock(&allproc_lock); 759 760 /* 761 * Nothing to do, back to sleep. 762 */ 763 if ((p = pp) == NULL) { 764 tsleep(&proc0, PVM, "sched", MAXSLP * hz / 2); 765 goto loop; 766 } 767 PROC_LOCK(p); 768 769 /* 770 * Another process may be bringing or may have already 771 * brought this process in while we traverse all threads. 772 * Or, this process may even be being swapped out again. 773 */ 774 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 775 PROC_UNLOCK(p); 776 goto loop; 777 } 778 779 /* 780 * We would like to bring someone in. (only if there is space). 781 * [What checks the space? ] 782 */ 783 faultin(p); 784 PROC_UNLOCK(p); 785 goto loop; 786 } 787 788 void 789 kick_proc0(void) 790 { 791 792 wakeup(&proc0); 793 } 794 795 #ifndef NO_SWAPPING 796 797 /* 798 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 799 */ 800 static int swap_idle_threshold1 = 2; 801 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 802 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 803 804 /* 805 * Swap_idle_threshold2 is the time that a process can be idle before 806 * it will be swapped out, if idle swapping is enabled. 807 */ 808 static int swap_idle_threshold2 = 10; 809 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 810 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 811 812 /* 813 * First, if any processes have been sleeping or stopped for at least 814 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 815 * no such processes exist, then the longest-sleeping or stopped 816 * process is swapped out. Finally, and only as a last resort, if 817 * there are no sleeping or stopped processes, the longest-resident 818 * process is swapped out. 819 */ 820 void 821 swapout_procs(action) 822 int action; 823 { 824 struct proc *p; 825 struct thread *td; 826 int didswap = 0; 827 828 retry: 829 sx_slock(&allproc_lock); 830 FOREACH_PROC_IN_SYSTEM(p) { 831 struct vmspace *vm; 832 int minslptime = 100000; 833 int slptime; 834 835 /* 836 * Watch out for a process in 837 * creation. It may have no 838 * address space or lock yet. 839 */ 840 if (p->p_state == PRS_NEW) 841 continue; 842 /* 843 * An aio daemon switches its 844 * address space while running. 845 * Perform a quick check whether 846 * a process has P_SYSTEM. 847 */ 848 if ((p->p_flag & P_SYSTEM) != 0) 849 continue; 850 /* 851 * Do not swapout a process that 852 * is waiting for VM data 853 * structures as there is a possible 854 * deadlock. Test this first as 855 * this may block. 856 * 857 * Lock the map until swapout 858 * finishes, or a thread of this 859 * process may attempt to alter 860 * the map. 861 */ 862 vm = vmspace_acquire_ref(p); 863 if (vm == NULL) 864 continue; 865 if (!vm_map_trylock(&vm->vm_map)) 866 goto nextproc1; 867 868 PROC_LOCK(p); 869 if (p->p_lock != 0 || 870 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 871 ) != 0) { 872 goto nextproc; 873 } 874 /* 875 * only aiod changes vmspace, however it will be 876 * skipped because of the if statement above checking 877 * for P_SYSTEM 878 */ 879 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 880 goto nextproc; 881 882 switch (p->p_state) { 883 default: 884 /* Don't swap out processes in any sort 885 * of 'special' state. */ 886 break; 887 888 case PRS_NORMAL: 889 /* 890 * do not swapout a realtime process 891 * Check all the thread groups.. 892 */ 893 FOREACH_THREAD_IN_PROC(p, td) { 894 thread_lock(td); 895 if (PRI_IS_REALTIME(td->td_pri_class)) { 896 thread_unlock(td); 897 goto nextproc; 898 } 899 slptime = (ticks - td->td_slptick) / hz; 900 /* 901 * Guarantee swap_idle_threshold1 902 * time in memory. 903 */ 904 if (slptime < swap_idle_threshold1) { 905 thread_unlock(td); 906 goto nextproc; 907 } 908 909 /* 910 * Do not swapout a process if it is 911 * waiting on a critical event of some 912 * kind or there is a thread whose 913 * pageable memory may be accessed. 914 * 915 * This could be refined to support 916 * swapping out a thread. 917 */ 918 if (!thread_safetoswapout(td)) { 919 thread_unlock(td); 920 goto nextproc; 921 } 922 /* 923 * If the system is under memory stress, 924 * or if we are swapping 925 * idle processes >= swap_idle_threshold2, 926 * then swap the process out. 927 */ 928 if (((action & VM_SWAP_NORMAL) == 0) && 929 (((action & VM_SWAP_IDLE) == 0) || 930 (slptime < swap_idle_threshold2))) { 931 thread_unlock(td); 932 goto nextproc; 933 } 934 935 if (minslptime > slptime) 936 minslptime = slptime; 937 thread_unlock(td); 938 } 939 940 /* 941 * If the pageout daemon didn't free enough pages, 942 * or if this process is idle and the system is 943 * configured to swap proactively, swap it out. 944 */ 945 if ((action & VM_SWAP_NORMAL) || 946 ((action & VM_SWAP_IDLE) && 947 (minslptime > swap_idle_threshold2))) { 948 if (swapout(p) == 0) 949 didswap++; 950 PROC_UNLOCK(p); 951 vm_map_unlock(&vm->vm_map); 952 vmspace_free(vm); 953 sx_sunlock(&allproc_lock); 954 goto retry; 955 } 956 } 957 nextproc: 958 PROC_UNLOCK(p); 959 vm_map_unlock(&vm->vm_map); 960 nextproc1: 961 vmspace_free(vm); 962 continue; 963 } 964 sx_sunlock(&allproc_lock); 965 /* 966 * If we swapped something out, and another process needed memory, 967 * then wakeup the sched process. 968 */ 969 if (didswap) 970 wakeup(&proc0); 971 } 972 973 static void 974 swapclear(p) 975 struct proc *p; 976 { 977 struct thread *td; 978 979 PROC_LOCK_ASSERT(p, MA_OWNED); 980 981 FOREACH_THREAD_IN_PROC(p, td) { 982 thread_lock(td); 983 td->td_flags |= TDF_INMEM; 984 td->td_flags &= ~TDF_SWAPINREQ; 985 TD_CLR_SWAPPED(td); 986 if (TD_CAN_RUN(td)) 987 if (setrunnable(td)) { 988 #ifdef INVARIANTS 989 /* 990 * XXX: We just cleared TDI_SWAPPED 991 * above and set TDF_INMEM, so this 992 * should never happen. 993 */ 994 panic("not waking up swapper"); 995 #endif 996 } 997 thread_unlock(td); 998 } 999 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 1000 p->p_flag |= P_INMEM; 1001 } 1002 1003 static int 1004 swapout(p) 1005 struct proc *p; 1006 { 1007 struct thread *td; 1008 1009 PROC_LOCK_ASSERT(p, MA_OWNED); 1010 #if defined(SWAP_DEBUG) 1011 printf("swapping out %d\n", p->p_pid); 1012 #endif 1013 1014 /* 1015 * The states of this process and its threads may have changed 1016 * by now. Assuming that there is only one pageout daemon thread, 1017 * this process should still be in memory. 1018 */ 1019 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1020 ("swapout: lost a swapout race?")); 1021 1022 /* 1023 * remember the process resident count 1024 */ 1025 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1026 /* 1027 * Check and mark all threads before we proceed. 1028 */ 1029 p->p_flag &= ~P_INMEM; 1030 p->p_flag |= P_SWAPPINGOUT; 1031 FOREACH_THREAD_IN_PROC(p, td) { 1032 thread_lock(td); 1033 if (!thread_safetoswapout(td)) { 1034 thread_unlock(td); 1035 swapclear(p); 1036 return (EBUSY); 1037 } 1038 td->td_flags &= ~TDF_INMEM; 1039 TD_SET_SWAPPED(td); 1040 thread_unlock(td); 1041 } 1042 td = FIRST_THREAD_IN_PROC(p); 1043 ++td->td_ru.ru_nswap; 1044 PROC_UNLOCK(p); 1045 1046 /* 1047 * This list is stable because all threads are now prevented from 1048 * running. The list is only modified in the context of a running 1049 * thread in this process. 1050 */ 1051 FOREACH_THREAD_IN_PROC(p, td) 1052 vm_thread_swapout(td); 1053 1054 PROC_LOCK(p); 1055 p->p_flag &= ~P_SWAPPINGOUT; 1056 p->p_swtick = ticks; 1057 return (0); 1058 } 1059 #endif /* !NO_SWAPPING */ 1060