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