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/resourcevar.h> 73 #include <sys/sched.h> 74 #include <sys/sf_buf.h> 75 #include <sys/shm.h> 76 #include <sys/vmmeter.h> 77 #include <sys/sx.h> 78 #include <sys/sysctl.h> 79 80 #include <sys/eventhandler.h> 81 #include <sys/kernel.h> 82 #include <sys/ktr.h> 83 #include <sys/unistd.h> 84 85 #include <vm/vm.h> 86 #include <vm/vm_param.h> 87 #include <vm/pmap.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_page.h> 90 #include <vm/vm_pageout.h> 91 #include <vm/vm_object.h> 92 #include <vm/vm_kern.h> 93 #include <vm/vm_extern.h> 94 #include <vm/vm_pager.h> 95 #include <vm/swap_pager.h> 96 97 extern int maxslp; 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 PROC_LOCK(curproc); 199 if (ptoa(npages + 200 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 201 lim_cur(curproc, RLIMIT_MEMLOCK)) { 202 PROC_UNLOCK(curproc); 203 return (ENOMEM); 204 } 205 PROC_UNLOCK(curproc); 206 #if 0 207 /* 208 * XXX - not yet 209 * 210 * The limit for transient usage of wired pages should be 211 * larger than for "permanent" wired pages (mlock()). 212 * 213 * Also, the sysctl code, which is the only present user 214 * of vslock(), does a hard loop on EAGAIN. 215 */ 216 if (npages + cnt.v_wire_count > vm_page_max_wired) 217 return (EAGAIN); 218 #endif 219 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 220 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 221 /* 222 * Return EFAULT on error to match copy{in,out}() behaviour 223 * rather than returning ENOMEM like mlock() would. 224 */ 225 return (error == KERN_SUCCESS ? 0 : EFAULT); 226 } 227 228 void 229 vsunlock(void *addr, size_t len) 230 { 231 232 /* Rely on the parameter sanity checks performed by vslock(). */ 233 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 234 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 235 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 236 } 237 238 /* 239 * Pin the page contained within the given object at the given offset. If the 240 * page is not resident, allocate and load it using the given object's pager. 241 * Return the pinned page if successful; otherwise, return NULL. 242 */ 243 static vm_page_t 244 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 245 { 246 vm_page_t m, ma[1]; 247 vm_pindex_t pindex; 248 int rv; 249 250 VM_OBJECT_LOCK(object); 251 pindex = OFF_TO_IDX(offset); 252 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 253 if (m->valid != VM_PAGE_BITS_ALL) { 254 ma[0] = m; 255 rv = vm_pager_get_pages(object, ma, 1, 0); 256 m = vm_page_lookup(object, pindex); 257 if (m == NULL) 258 goto out; 259 if (rv != VM_PAGER_OK) { 260 vm_page_lock(m); 261 vm_page_free(m); 262 vm_page_unlock(m); 263 m = NULL; 264 goto out; 265 } 266 } 267 vm_page_lock(m); 268 vm_page_hold(m); 269 vm_page_unlock(m); 270 vm_page_wakeup(m); 271 out: 272 VM_OBJECT_UNLOCK(object); 273 return (m); 274 } 275 276 /* 277 * Return a CPU private mapping to the page at the given offset within the 278 * given object. The page is pinned before it is mapped. 279 */ 280 struct sf_buf * 281 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 282 { 283 vm_page_t m; 284 285 m = vm_imgact_hold_page(object, offset); 286 if (m == NULL) 287 return (NULL); 288 sched_pin(); 289 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 290 } 291 292 /* 293 * Destroy the given CPU private mapping and unpin the page that it mapped. 294 */ 295 void 296 vm_imgact_unmap_page(struct sf_buf *sf) 297 { 298 vm_page_t m; 299 300 m = sf_buf_page(sf); 301 sf_buf_free(sf); 302 sched_unpin(); 303 vm_page_lock(m); 304 vm_page_unhold(m); 305 vm_page_unlock(m); 306 } 307 308 void 309 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz) 310 { 311 312 pmap_sync_icache(map->pmap, va, sz); 313 } 314 315 struct kstack_cache_entry { 316 vm_object_t ksobj; 317 struct kstack_cache_entry *next_ks_entry; 318 }; 319 320 static struct kstack_cache_entry *kstack_cache; 321 static int kstack_cache_size = 128; 322 static int kstacks; 323 static struct mtx kstack_cache_mtx; 324 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 325 ""); 326 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 327 ""); 328 329 #ifndef KSTACK_MAX_PAGES 330 #define KSTACK_MAX_PAGES 32 331 #endif 332 333 /* 334 * Create the kernel stack (including pcb for i386) for a new thread. 335 * This routine directly affects the fork perf for a process and 336 * create performance for a thread. 337 */ 338 int 339 vm_thread_new(struct thread *td, int pages) 340 { 341 vm_object_t ksobj; 342 vm_offset_t ks; 343 vm_page_t m, ma[KSTACK_MAX_PAGES]; 344 struct kstack_cache_entry *ks_ce; 345 int i; 346 347 /* Bounds check */ 348 if (pages <= 1) 349 pages = KSTACK_PAGES; 350 else if (pages > KSTACK_MAX_PAGES) 351 pages = KSTACK_MAX_PAGES; 352 353 if (pages == KSTACK_PAGES) { 354 mtx_lock(&kstack_cache_mtx); 355 if (kstack_cache != NULL) { 356 ks_ce = kstack_cache; 357 kstack_cache = ks_ce->next_ks_entry; 358 mtx_unlock(&kstack_cache_mtx); 359 360 td->td_kstack_obj = ks_ce->ksobj; 361 td->td_kstack = (vm_offset_t)ks_ce; 362 td->td_kstack_pages = KSTACK_PAGES; 363 return (1); 364 } 365 mtx_unlock(&kstack_cache_mtx); 366 } 367 368 /* 369 * Allocate an object for the kstack. 370 */ 371 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 372 373 /* 374 * Get a kernel virtual address for this thread's kstack. 375 */ 376 #if defined(__mips__) 377 /* 378 * We need to align the kstack's mapped address to fit within 379 * a single TLB entry. 380 */ 381 ks = kmem_alloc_nofault_space(kernel_map, 382 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE, VMFS_TLB_ALIGNED_SPACE); 383 #else 384 ks = kmem_alloc_nofault(kernel_map, 385 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 386 #endif 387 if (ks == 0) { 388 printf("vm_thread_new: kstack allocation failed\n"); 389 vm_object_deallocate(ksobj); 390 return (0); 391 } 392 393 atomic_add_int(&kstacks, 1); 394 if (KSTACK_GUARD_PAGES != 0) { 395 pmap_qremove(ks, KSTACK_GUARD_PAGES); 396 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 397 } 398 td->td_kstack_obj = ksobj; 399 td->td_kstack = ks; 400 /* 401 * Knowing the number of pages allocated is useful when you 402 * want to deallocate them. 403 */ 404 td->td_kstack_pages = pages; 405 /* 406 * For the length of the stack, link in a real page of ram for each 407 * page of stack. 408 */ 409 VM_OBJECT_LOCK(ksobj); 410 for (i = 0; i < pages; i++) { 411 /* 412 * Get a kernel stack page. 413 */ 414 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 415 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 416 ma[i] = m; 417 m->valid = VM_PAGE_BITS_ALL; 418 } 419 VM_OBJECT_UNLOCK(ksobj); 420 pmap_qenter(ks, ma, pages); 421 return (1); 422 } 423 424 static void 425 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 426 { 427 vm_page_t m; 428 int i; 429 430 atomic_add_int(&kstacks, -1); 431 pmap_qremove(ks, pages); 432 VM_OBJECT_LOCK(ksobj); 433 for (i = 0; i < pages; i++) { 434 m = vm_page_lookup(ksobj, i); 435 if (m == NULL) 436 panic("vm_thread_dispose: kstack already missing?"); 437 vm_page_lock(m); 438 vm_page_unwire(m, 0); 439 vm_page_free(m); 440 vm_page_unlock(m); 441 } 442 VM_OBJECT_UNLOCK(ksobj); 443 vm_object_deallocate(ksobj); 444 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 445 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 446 } 447 448 /* 449 * Dispose of a thread's kernel stack. 450 */ 451 void 452 vm_thread_dispose(struct thread *td) 453 { 454 vm_object_t ksobj; 455 vm_offset_t ks; 456 struct kstack_cache_entry *ks_ce; 457 int pages; 458 459 pages = td->td_kstack_pages; 460 ksobj = td->td_kstack_obj; 461 ks = td->td_kstack; 462 td->td_kstack = 0; 463 td->td_kstack_pages = 0; 464 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 465 ks_ce = (struct kstack_cache_entry *)ks; 466 ks_ce->ksobj = ksobj; 467 mtx_lock(&kstack_cache_mtx); 468 ks_ce->next_ks_entry = kstack_cache; 469 kstack_cache = ks_ce; 470 mtx_unlock(&kstack_cache_mtx); 471 return; 472 } 473 vm_thread_stack_dispose(ksobj, ks, pages); 474 } 475 476 static void 477 vm_thread_stack_lowmem(void *nulll) 478 { 479 struct kstack_cache_entry *ks_ce, *ks_ce1; 480 481 mtx_lock(&kstack_cache_mtx); 482 ks_ce = kstack_cache; 483 kstack_cache = NULL; 484 mtx_unlock(&kstack_cache_mtx); 485 486 while (ks_ce != NULL) { 487 ks_ce1 = ks_ce; 488 ks_ce = ks_ce->next_ks_entry; 489 490 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 491 KSTACK_PAGES); 492 } 493 } 494 495 static void 496 kstack_cache_init(void *nulll) 497 { 498 499 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 500 EVENTHANDLER_PRI_ANY); 501 } 502 503 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 504 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 505 506 #ifndef NO_SWAPPING 507 /* 508 * Allow a thread's kernel stack to be paged out. 509 */ 510 static void 511 vm_thread_swapout(struct thread *td) 512 { 513 vm_object_t ksobj; 514 vm_page_t m; 515 int i, pages; 516 517 cpu_thread_swapout(td); 518 pages = td->td_kstack_pages; 519 ksobj = td->td_kstack_obj; 520 pmap_qremove(td->td_kstack, pages); 521 VM_OBJECT_LOCK(ksobj); 522 for (i = 0; i < pages; i++) { 523 m = vm_page_lookup(ksobj, i); 524 if (m == NULL) 525 panic("vm_thread_swapout: kstack already missing?"); 526 vm_page_dirty(m); 527 vm_page_lock(m); 528 vm_page_unwire(m, 0); 529 vm_page_unlock(m); 530 } 531 VM_OBJECT_UNLOCK(ksobj); 532 } 533 534 /* 535 * Bring the kernel stack for a specified thread back in. 536 */ 537 static void 538 vm_thread_swapin(struct thread *td) 539 { 540 vm_object_t ksobj; 541 vm_page_t ma[KSTACK_MAX_PAGES]; 542 int i, j, k, pages, rv; 543 544 pages = td->td_kstack_pages; 545 ksobj = td->td_kstack_obj; 546 VM_OBJECT_LOCK(ksobj); 547 for (i = 0; i < pages; i++) 548 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY | 549 VM_ALLOC_WIRED); 550 for (i = 0; i < pages; i++) { 551 if (ma[i]->valid != VM_PAGE_BITS_ALL) { 552 KASSERT(ma[i]->oflags & VPO_BUSY, 553 ("lost busy 1")); 554 vm_object_pip_add(ksobj, 1); 555 for (j = i + 1; j < pages; j++) { 556 KASSERT(ma[j]->valid == VM_PAGE_BITS_ALL || 557 (ma[j]->oflags & VPO_BUSY), 558 ("lost busy 2")); 559 if (ma[j]->valid == VM_PAGE_BITS_ALL) 560 break; 561 } 562 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0); 563 if (rv != VM_PAGER_OK) 564 panic("vm_thread_swapin: cannot get kstack for proc: %d", 565 td->td_proc->p_pid); 566 vm_object_pip_wakeup(ksobj); 567 for (k = i; k < j; k++) 568 ma[k] = vm_page_lookup(ksobj, k); 569 vm_page_wakeup(ma[i]); 570 } else if (ma[i]->oflags & VPO_BUSY) 571 vm_page_wakeup(ma[i]); 572 } 573 VM_OBJECT_UNLOCK(ksobj); 574 pmap_qenter(td->td_kstack, ma, pages); 575 cpu_thread_swapin(td); 576 } 577 #endif /* !NO_SWAPPING */ 578 579 /* 580 * Implement fork's actions on an address space. 581 * Here we arrange for the address space to be copied or referenced, 582 * allocate a user struct (pcb and kernel stack), then call the 583 * machine-dependent layer to fill those in and make the new process 584 * ready to run. The new process is set up so that it returns directly 585 * to user mode to avoid stack copying and relocation problems. 586 */ 587 int 588 vm_forkproc(td, p2, td2, vm2, flags) 589 struct thread *td; 590 struct proc *p2; 591 struct thread *td2; 592 struct vmspace *vm2; 593 int flags; 594 { 595 struct proc *p1 = td->td_proc; 596 int error; 597 598 if ((flags & RFPROC) == 0) { 599 /* 600 * Divorce the memory, if it is shared, essentially 601 * this changes shared memory amongst threads, into 602 * COW locally. 603 */ 604 if ((flags & RFMEM) == 0) { 605 if (p1->p_vmspace->vm_refcnt > 1) { 606 error = vmspace_unshare(p1); 607 if (error) 608 return (error); 609 } 610 } 611 cpu_fork(td, p2, td2, flags); 612 return (0); 613 } 614 615 if (flags & RFMEM) { 616 p2->p_vmspace = p1->p_vmspace; 617 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 618 } 619 620 while (vm_page_count_severe()) { 621 VM_WAIT; 622 } 623 624 if ((flags & RFMEM) == 0) { 625 p2->p_vmspace = vm2; 626 if (p1->p_vmspace->vm_shm) 627 shmfork(p1, p2); 628 } 629 630 /* 631 * cpu_fork will copy and update the pcb, set up the kernel stack, 632 * and make the child ready to run. 633 */ 634 cpu_fork(td, p2, td2, flags); 635 return (0); 636 } 637 638 /* 639 * Called after process has been wait(2)'ed apon and is being reaped. 640 * The idea is to reclaim resources that we could not reclaim while 641 * the process was still executing. 642 */ 643 void 644 vm_waitproc(p) 645 struct proc *p; 646 { 647 648 vmspace_exitfree(p); /* and clean-out the vmspace */ 649 } 650 651 void 652 faultin(p) 653 struct proc *p; 654 { 655 #ifdef NO_SWAPPING 656 657 PROC_LOCK_ASSERT(p, MA_OWNED); 658 if ((p->p_flag & P_INMEM) == 0) 659 panic("faultin: proc swapped out with NO_SWAPPING!"); 660 #else /* !NO_SWAPPING */ 661 struct thread *td; 662 663 PROC_LOCK_ASSERT(p, MA_OWNED); 664 /* 665 * If another process is swapping in this process, 666 * just wait until it finishes. 667 */ 668 if (p->p_flag & P_SWAPPINGIN) { 669 while (p->p_flag & P_SWAPPINGIN) 670 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 671 return; 672 } 673 if ((p->p_flag & P_INMEM) == 0) { 674 /* 675 * Don't let another thread swap process p out while we are 676 * busy swapping it in. 677 */ 678 ++p->p_lock; 679 p->p_flag |= P_SWAPPINGIN; 680 PROC_UNLOCK(p); 681 682 /* 683 * We hold no lock here because the list of threads 684 * can not change while all threads in the process are 685 * swapped out. 686 */ 687 FOREACH_THREAD_IN_PROC(p, td) 688 vm_thread_swapin(td); 689 PROC_LOCK(p); 690 swapclear(p); 691 p->p_swtick = ticks; 692 693 wakeup(&p->p_flag); 694 695 /* Allow other threads to swap p out now. */ 696 --p->p_lock; 697 } 698 #endif /* NO_SWAPPING */ 699 } 700 701 /* 702 * This swapin algorithm attempts to swap-in processes only if there 703 * is enough space for them. Of course, if a process waits for a long 704 * time, it will be swapped in anyway. 705 * 706 * Giant is held on entry. 707 */ 708 /* ARGSUSED*/ 709 static void 710 scheduler(dummy) 711 void *dummy; 712 { 713 struct proc *p; 714 struct thread *td; 715 struct proc *pp; 716 int slptime; 717 int swtime; 718 int ppri; 719 int pri; 720 721 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 722 mtx_unlock(&Giant); 723 724 loop: 725 if (vm_page_count_min()) { 726 VM_WAIT; 727 goto loop; 728 } 729 730 pp = NULL; 731 ppri = INT_MIN; 732 sx_slock(&allproc_lock); 733 FOREACH_PROC_IN_SYSTEM(p) { 734 PROC_LOCK(p); 735 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 736 PROC_UNLOCK(p); 737 continue; 738 } 739 swtime = (ticks - p->p_swtick) / hz; 740 FOREACH_THREAD_IN_PROC(p, td) { 741 /* 742 * An otherwise runnable thread of a process 743 * swapped out has only the TDI_SWAPPED bit set. 744 * 745 */ 746 thread_lock(td); 747 if (td->td_inhibitors == TDI_SWAPPED) { 748 slptime = (ticks - td->td_slptick) / hz; 749 pri = swtime + slptime; 750 if ((td->td_flags & TDF_SWAPINREQ) == 0) 751 pri -= p->p_nice * 8; 752 /* 753 * if this thread is higher priority 754 * and there is enough space, then select 755 * this process instead of the previous 756 * selection. 757 */ 758 if (pri > ppri) { 759 pp = p; 760 ppri = pri; 761 } 762 } 763 thread_unlock(td); 764 } 765 PROC_UNLOCK(p); 766 } 767 sx_sunlock(&allproc_lock); 768 769 /* 770 * Nothing to do, back to sleep. 771 */ 772 if ((p = pp) == NULL) { 773 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 774 goto loop; 775 } 776 PROC_LOCK(p); 777 778 /* 779 * Another process may be bringing or may have already 780 * brought this process in while we traverse all threads. 781 * Or, this process may even be being swapped out again. 782 */ 783 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 784 PROC_UNLOCK(p); 785 goto loop; 786 } 787 788 /* 789 * We would like to bring someone in. (only if there is space). 790 * [What checks the space? ] 791 */ 792 faultin(p); 793 PROC_UNLOCK(p); 794 goto loop; 795 } 796 797 void 798 kick_proc0(void) 799 { 800 801 wakeup(&proc0); 802 } 803 804 #ifndef NO_SWAPPING 805 806 /* 807 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 808 */ 809 static int swap_idle_threshold1 = 2; 810 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 811 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 812 813 /* 814 * Swap_idle_threshold2 is the time that a process can be idle before 815 * it will be swapped out, if idle swapping is enabled. 816 */ 817 static int swap_idle_threshold2 = 10; 818 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 819 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 820 821 /* 822 * Swapout is driven by the pageout daemon. Very simple, we find eligible 823 * procs and swap out their stacks. We try to always "swap" at least one 824 * process in case we need the room for a swapin. 825 * If any procs have been sleeping/stopped for at least maxslp seconds, 826 * they are swapped. Else, we swap the longest-sleeping or stopped process, 827 * if any, otherwise the longest-resident process. 828 */ 829 void 830 swapout_procs(action) 831 int action; 832 { 833 struct proc *p; 834 struct thread *td; 835 int didswap = 0; 836 837 retry: 838 sx_slock(&allproc_lock); 839 FOREACH_PROC_IN_SYSTEM(p) { 840 struct vmspace *vm; 841 int minslptime = 100000; 842 int slptime; 843 844 /* 845 * Watch out for a process in 846 * creation. It may have no 847 * address space or lock yet. 848 */ 849 if (p->p_state == PRS_NEW) 850 continue; 851 /* 852 * An aio daemon switches its 853 * address space while running. 854 * Perform a quick check whether 855 * a process has P_SYSTEM. 856 */ 857 if ((p->p_flag & P_SYSTEM) != 0) 858 continue; 859 /* 860 * Do not swapout a process that 861 * is waiting for VM data 862 * structures as there is a possible 863 * deadlock. Test this first as 864 * this may block. 865 * 866 * Lock the map until swapout 867 * finishes, or a thread of this 868 * process may attempt to alter 869 * the map. 870 */ 871 vm = vmspace_acquire_ref(p); 872 if (vm == NULL) 873 continue; 874 if (!vm_map_trylock(&vm->vm_map)) 875 goto nextproc1; 876 877 PROC_LOCK(p); 878 if (p->p_lock != 0 || 879 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 880 ) != 0) { 881 goto nextproc; 882 } 883 /* 884 * only aiod changes vmspace, however it will be 885 * skipped because of the if statement above checking 886 * for P_SYSTEM 887 */ 888 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 889 goto nextproc; 890 891 switch (p->p_state) { 892 default: 893 /* Don't swap out processes in any sort 894 * of 'special' state. */ 895 break; 896 897 case PRS_NORMAL: 898 /* 899 * do not swapout a realtime process 900 * Check all the thread groups.. 901 */ 902 FOREACH_THREAD_IN_PROC(p, td) { 903 thread_lock(td); 904 if (PRI_IS_REALTIME(td->td_pri_class)) { 905 thread_unlock(td); 906 goto nextproc; 907 } 908 slptime = (ticks - td->td_slptick) / hz; 909 /* 910 * Guarantee swap_idle_threshold1 911 * time in memory. 912 */ 913 if (slptime < swap_idle_threshold1) { 914 thread_unlock(td); 915 goto nextproc; 916 } 917 918 /* 919 * Do not swapout a process if it is 920 * waiting on a critical event of some 921 * kind or there is a thread whose 922 * pageable memory may be accessed. 923 * 924 * This could be refined to support 925 * swapping out a thread. 926 */ 927 if (!thread_safetoswapout(td)) { 928 thread_unlock(td); 929 goto nextproc; 930 } 931 /* 932 * If the system is under memory stress, 933 * or if we are swapping 934 * idle processes >= swap_idle_threshold2, 935 * then swap the process out. 936 */ 937 if (((action & VM_SWAP_NORMAL) == 0) && 938 (((action & VM_SWAP_IDLE) == 0) || 939 (slptime < swap_idle_threshold2))) { 940 thread_unlock(td); 941 goto nextproc; 942 } 943 944 if (minslptime > slptime) 945 minslptime = slptime; 946 thread_unlock(td); 947 } 948 949 /* 950 * If the pageout daemon didn't free enough pages, 951 * or if this process is idle and the system is 952 * configured to swap proactively, swap it out. 953 */ 954 if ((action & VM_SWAP_NORMAL) || 955 ((action & VM_SWAP_IDLE) && 956 (minslptime > swap_idle_threshold2))) { 957 if (swapout(p) == 0) 958 didswap++; 959 PROC_UNLOCK(p); 960 vm_map_unlock(&vm->vm_map); 961 vmspace_free(vm); 962 sx_sunlock(&allproc_lock); 963 goto retry; 964 } 965 } 966 nextproc: 967 PROC_UNLOCK(p); 968 vm_map_unlock(&vm->vm_map); 969 nextproc1: 970 vmspace_free(vm); 971 continue; 972 } 973 sx_sunlock(&allproc_lock); 974 /* 975 * If we swapped something out, and another process needed memory, 976 * then wakeup the sched process. 977 */ 978 if (didswap) 979 wakeup(&proc0); 980 } 981 982 static void 983 swapclear(p) 984 struct proc *p; 985 { 986 struct thread *td; 987 988 PROC_LOCK_ASSERT(p, MA_OWNED); 989 990 FOREACH_THREAD_IN_PROC(p, td) { 991 thread_lock(td); 992 td->td_flags |= TDF_INMEM; 993 td->td_flags &= ~TDF_SWAPINREQ; 994 TD_CLR_SWAPPED(td); 995 if (TD_CAN_RUN(td)) 996 if (setrunnable(td)) { 997 #ifdef INVARIANTS 998 /* 999 * XXX: We just cleared TDI_SWAPPED 1000 * above and set TDF_INMEM, so this 1001 * should never happen. 1002 */ 1003 panic("not waking up swapper"); 1004 #endif 1005 } 1006 thread_unlock(td); 1007 } 1008 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 1009 p->p_flag |= P_INMEM; 1010 } 1011 1012 static int 1013 swapout(p) 1014 struct proc *p; 1015 { 1016 struct thread *td; 1017 1018 PROC_LOCK_ASSERT(p, MA_OWNED); 1019 #if defined(SWAP_DEBUG) 1020 printf("swapping out %d\n", p->p_pid); 1021 #endif 1022 1023 /* 1024 * The states of this process and its threads may have changed 1025 * by now. Assuming that there is only one pageout daemon thread, 1026 * this process should still be in memory. 1027 */ 1028 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1029 ("swapout: lost a swapout race?")); 1030 1031 /* 1032 * remember the process resident count 1033 */ 1034 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1035 /* 1036 * Check and mark all threads before we proceed. 1037 */ 1038 p->p_flag &= ~P_INMEM; 1039 p->p_flag |= P_SWAPPINGOUT; 1040 FOREACH_THREAD_IN_PROC(p, td) { 1041 thread_lock(td); 1042 if (!thread_safetoswapout(td)) { 1043 thread_unlock(td); 1044 swapclear(p); 1045 return (EBUSY); 1046 } 1047 td->td_flags &= ~TDF_INMEM; 1048 TD_SET_SWAPPED(td); 1049 thread_unlock(td); 1050 } 1051 td = FIRST_THREAD_IN_PROC(p); 1052 ++td->td_ru.ru_nswap; 1053 PROC_UNLOCK(p); 1054 1055 /* 1056 * This list is stable because all threads are now prevented from 1057 * running. The list is only modified in the context of a running 1058 * thread in this process. 1059 */ 1060 FOREACH_THREAD_IN_PROC(p, td) 1061 vm_thread_swapout(td); 1062 1063 PROC_LOCK(p); 1064 p->p_flag &= ~P_SWAPPINGOUT; 1065 p->p_swtick = ticks; 1066 return (0); 1067 } 1068 #endif /* !NO_SWAPPING */ 1069