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/8.1/sys/vm/vm_glue.c 208041 2010-05-13 18:17:01Z kib $"); 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 * Note: proc0 from proc.h 103 */ 104 static void vm_init_limits(void *); 105 SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0); 106 107 /* 108 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 109 * 110 * Note: run scheduling should be divorced from the vm system. 111 */ 112 static void scheduler(void *); 113 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL); 114 115 #ifndef NO_SWAPPING 116 static int swapout(struct proc *); 117 static void swapclear(struct proc *); 118 #endif 119 120 /* 121 * MPSAFE 122 * 123 * WARNING! This code calls vm_map_check_protection() which only checks 124 * the associated vm_map_entry range. It does not determine whether the 125 * contents of the memory is actually readable or writable. In most cases 126 * just checking the vm_map_entry is sufficient within the kernel's address 127 * space. 128 */ 129 int 130 kernacc(addr, len, rw) 131 void *addr; 132 int len, rw; 133 { 134 boolean_t rv; 135 vm_offset_t saddr, eaddr; 136 vm_prot_t prot; 137 138 KASSERT((rw & ~VM_PROT_ALL) == 0, 139 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 140 141 if ((vm_offset_t)addr + len > kernel_map->max_offset || 142 (vm_offset_t)addr + len < (vm_offset_t)addr) 143 return (FALSE); 144 145 prot = rw; 146 saddr = trunc_page((vm_offset_t)addr); 147 eaddr = round_page((vm_offset_t)addr + len); 148 vm_map_lock_read(kernel_map); 149 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 150 vm_map_unlock_read(kernel_map); 151 return (rv == TRUE); 152 } 153 154 /* 155 * MPSAFE 156 * 157 * WARNING! This code calls vm_map_check_protection() which only checks 158 * the associated vm_map_entry range. It does not determine whether the 159 * contents of the memory is actually readable or writable. vmapbuf(), 160 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 161 * used in conjuction with this call. 162 */ 163 int 164 useracc(addr, len, rw) 165 void *addr; 166 int len, rw; 167 { 168 boolean_t rv; 169 vm_prot_t prot; 170 vm_map_t map; 171 172 KASSERT((rw & ~VM_PROT_ALL) == 0, 173 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 174 prot = rw; 175 map = &curproc->p_vmspace->vm_map; 176 if ((vm_offset_t)addr + len > vm_map_max(map) || 177 (vm_offset_t)addr + len < (vm_offset_t)addr) { 178 return (FALSE); 179 } 180 vm_map_lock_read(map); 181 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 182 round_page((vm_offset_t)addr + len), prot); 183 vm_map_unlock_read(map); 184 return (rv == TRUE); 185 } 186 187 int 188 vslock(void *addr, size_t len) 189 { 190 vm_offset_t end, last, start; 191 vm_size_t npages; 192 int error; 193 194 last = (vm_offset_t)addr + len; 195 start = trunc_page((vm_offset_t)addr); 196 end = round_page(last); 197 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 198 return (EINVAL); 199 npages = atop(end - start); 200 if (npages > vm_page_max_wired) 201 return (ENOMEM); 202 PROC_LOCK(curproc); 203 if (ptoa(npages + 204 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 205 lim_cur(curproc, RLIMIT_MEMLOCK)) { 206 PROC_UNLOCK(curproc); 207 return (ENOMEM); 208 } 209 PROC_UNLOCK(curproc); 210 #if 0 211 /* 212 * XXX - not yet 213 * 214 * The limit for transient usage of wired pages should be 215 * larger than for "permanent" wired pages (mlock()). 216 * 217 * Also, the sysctl code, which is the only present user 218 * of vslock(), does a hard loop on EAGAIN. 219 */ 220 if (npages + cnt.v_wire_count > vm_page_max_wired) 221 return (EAGAIN); 222 #endif 223 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 224 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 225 /* 226 * Return EFAULT on error to match copy{in,out}() behaviour 227 * rather than returning ENOMEM like mlock() would. 228 */ 229 return (error == KERN_SUCCESS ? 0 : EFAULT); 230 } 231 232 void 233 vsunlock(void *addr, size_t len) 234 { 235 236 /* Rely on the parameter sanity checks performed by vslock(). */ 237 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 238 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 239 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 240 } 241 242 /* 243 * Pin the page contained within the given object at the given offset. If the 244 * page is not resident, allocate and load it using the given object's pager. 245 * Return the pinned page if successful; otherwise, return NULL. 246 */ 247 static vm_page_t 248 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 249 { 250 vm_page_t m, ma[1]; 251 vm_pindex_t pindex; 252 int rv; 253 254 VM_OBJECT_LOCK(object); 255 pindex = OFF_TO_IDX(offset); 256 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 257 if (m->valid != VM_PAGE_BITS_ALL) { 258 ma[0] = m; 259 rv = vm_pager_get_pages(object, ma, 1, 0); 260 m = vm_page_lookup(object, pindex); 261 if (m == NULL) 262 goto out; 263 if (rv != VM_PAGER_OK) { 264 vm_page_lock_queues(); 265 vm_page_free(m); 266 vm_page_unlock_queues(); 267 m = NULL; 268 goto out; 269 } 270 } 271 vm_page_lock_queues(); 272 vm_page_hold(m); 273 vm_page_unlock_queues(); 274 vm_page_wakeup(m); 275 out: 276 VM_OBJECT_UNLOCK(object); 277 return (m); 278 } 279 280 /* 281 * Return a CPU private mapping to the page at the given offset within the 282 * given object. The page is pinned before it is mapped. 283 */ 284 struct sf_buf * 285 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 286 { 287 vm_page_t m; 288 289 m = vm_imgact_hold_page(object, offset); 290 if (m == NULL) 291 return (NULL); 292 sched_pin(); 293 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 294 } 295 296 /* 297 * Destroy the given CPU private mapping and unpin the page that it mapped. 298 */ 299 void 300 vm_imgact_unmap_page(struct sf_buf *sf) 301 { 302 vm_page_t m; 303 304 m = sf_buf_page(sf); 305 sf_buf_free(sf); 306 sched_unpin(); 307 vm_page_lock_queues(); 308 vm_page_unhold(m); 309 vm_page_unlock_queues(); 310 } 311 312 void 313 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz) 314 { 315 316 pmap_sync_icache(map->pmap, va, sz); 317 } 318 319 struct kstack_cache_entry { 320 vm_object_t ksobj; 321 struct kstack_cache_entry *next_ks_entry; 322 }; 323 324 static struct kstack_cache_entry *kstack_cache; 325 static int kstack_cache_size = 128; 326 static int kstacks; 327 static struct mtx kstack_cache_mtx; 328 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 329 ""); 330 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 331 ""); 332 333 #ifndef KSTACK_MAX_PAGES 334 #define KSTACK_MAX_PAGES 32 335 #endif 336 337 /* 338 * Create the kernel stack (including pcb for i386) for a new thread. 339 * This routine directly affects the fork perf for a process and 340 * create performance for a thread. 341 */ 342 int 343 vm_thread_new(struct thread *td, int pages) 344 { 345 vm_object_t ksobj; 346 vm_offset_t ks; 347 vm_page_t m, ma[KSTACK_MAX_PAGES]; 348 struct kstack_cache_entry *ks_ce; 349 int i; 350 351 /* Bounds check */ 352 if (pages <= 1) 353 pages = KSTACK_PAGES; 354 else if (pages > KSTACK_MAX_PAGES) 355 pages = KSTACK_MAX_PAGES; 356 357 if (pages == KSTACK_PAGES) { 358 mtx_lock(&kstack_cache_mtx); 359 if (kstack_cache != NULL) { 360 ks_ce = kstack_cache; 361 kstack_cache = ks_ce->next_ks_entry; 362 mtx_unlock(&kstack_cache_mtx); 363 364 td->td_kstack_obj = ks_ce->ksobj; 365 td->td_kstack = (vm_offset_t)ks_ce; 366 td->td_kstack_pages = KSTACK_PAGES; 367 return (1); 368 } 369 mtx_unlock(&kstack_cache_mtx); 370 } 371 372 /* 373 * Allocate an object for the kstack. 374 */ 375 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 376 377 /* 378 * Get a kernel virtual address for this thread's kstack. 379 */ 380 ks = kmem_alloc_nofault(kernel_map, 381 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 382 if (ks == 0) { 383 printf("vm_thread_new: kstack allocation failed\n"); 384 vm_object_deallocate(ksobj); 385 return (0); 386 } 387 388 atomic_add_int(&kstacks, 1); 389 if (KSTACK_GUARD_PAGES != 0) { 390 pmap_qremove(ks, KSTACK_GUARD_PAGES); 391 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 392 } 393 td->td_kstack_obj = ksobj; 394 td->td_kstack = ks; 395 /* 396 * Knowing the number of pages allocated is useful when you 397 * want to deallocate them. 398 */ 399 td->td_kstack_pages = pages; 400 /* 401 * For the length of the stack, link in a real page of ram for each 402 * page of stack. 403 */ 404 VM_OBJECT_LOCK(ksobj); 405 for (i = 0; i < pages; i++) { 406 /* 407 * Get a kernel stack page. 408 */ 409 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 410 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 411 ma[i] = m; 412 m->valid = VM_PAGE_BITS_ALL; 413 } 414 VM_OBJECT_UNLOCK(ksobj); 415 pmap_qenter(ks, ma, pages); 416 return (1); 417 } 418 419 static void 420 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 421 { 422 vm_page_t m; 423 int i; 424 425 atomic_add_int(&kstacks, -1); 426 pmap_qremove(ks, pages); 427 VM_OBJECT_LOCK(ksobj); 428 for (i = 0; i < pages; i++) { 429 m = vm_page_lookup(ksobj, i); 430 if (m == NULL) 431 panic("vm_thread_dispose: kstack already missing?"); 432 vm_page_lock_queues(); 433 vm_page_unwire(m, 0); 434 vm_page_free(m); 435 vm_page_unlock_queues(); 436 } 437 VM_OBJECT_UNLOCK(ksobj); 438 vm_object_deallocate(ksobj); 439 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 440 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 441 } 442 443 /* 444 * Dispose of a thread's kernel stack. 445 */ 446 void 447 vm_thread_dispose(struct thread *td) 448 { 449 vm_object_t ksobj; 450 vm_offset_t ks; 451 struct kstack_cache_entry *ks_ce; 452 int pages; 453 454 pages = td->td_kstack_pages; 455 ksobj = td->td_kstack_obj; 456 ks = td->td_kstack; 457 td->td_kstack = 0; 458 td->td_kstack_pages = 0; 459 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 460 ks_ce = (struct kstack_cache_entry *)ks; 461 ks_ce->ksobj = ksobj; 462 mtx_lock(&kstack_cache_mtx); 463 ks_ce->next_ks_entry = kstack_cache; 464 kstack_cache = ks_ce; 465 mtx_unlock(&kstack_cache_mtx); 466 return; 467 } 468 vm_thread_stack_dispose(ksobj, ks, pages); 469 } 470 471 static void 472 vm_thread_stack_lowmem(void *nulll) 473 { 474 struct kstack_cache_entry *ks_ce, *ks_ce1; 475 476 mtx_lock(&kstack_cache_mtx); 477 ks_ce = kstack_cache; 478 kstack_cache = NULL; 479 mtx_unlock(&kstack_cache_mtx); 480 481 while (ks_ce != NULL) { 482 ks_ce1 = ks_ce; 483 ks_ce = ks_ce->next_ks_entry; 484 485 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 486 KSTACK_PAGES); 487 } 488 } 489 490 static void 491 kstack_cache_init(void *nulll) 492 { 493 494 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 495 EVENTHANDLER_PRI_ANY); 496 } 497 498 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 499 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 500 501 /* 502 * Allow a thread's kernel stack to be paged out. 503 */ 504 void 505 vm_thread_swapout(struct thread *td) 506 { 507 vm_object_t ksobj; 508 vm_page_t m; 509 int i, pages; 510 511 cpu_thread_swapout(td); 512 pages = td->td_kstack_pages; 513 ksobj = td->td_kstack_obj; 514 pmap_qremove(td->td_kstack, pages); 515 VM_OBJECT_LOCK(ksobj); 516 for (i = 0; i < pages; i++) { 517 m = vm_page_lookup(ksobj, i); 518 if (m == NULL) 519 panic("vm_thread_swapout: kstack already missing?"); 520 vm_page_lock_queues(); 521 vm_page_dirty(m); 522 vm_page_unwire(m, 0); 523 vm_page_unlock_queues(); 524 } 525 VM_OBJECT_UNLOCK(ksobj); 526 } 527 528 /* 529 * Bring the kernel stack for a specified thread back in. 530 */ 531 void 532 vm_thread_swapin(struct thread *td) 533 { 534 vm_object_t ksobj; 535 vm_page_t ma[KSTACK_MAX_PAGES]; 536 int i, j, k, pages, rv; 537 538 pages = td->td_kstack_pages; 539 ksobj = td->td_kstack_obj; 540 VM_OBJECT_LOCK(ksobj); 541 for (i = 0; i < pages; i++) 542 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY | 543 VM_ALLOC_WIRED); 544 for (i = 0; i < pages; i++) { 545 if (ma[i]->valid != VM_PAGE_BITS_ALL) { 546 KASSERT(ma[i]->oflags & VPO_BUSY, 547 ("lost busy 1")); 548 vm_object_pip_add(ksobj, 1); 549 for (j = i + 1; j < pages; j++) { 550 KASSERT(ma[j]->valid == VM_PAGE_BITS_ALL || 551 (ma[j]->oflags & VPO_BUSY), 552 ("lost busy 2")); 553 if (ma[j]->valid == VM_PAGE_BITS_ALL) 554 break; 555 } 556 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0); 557 if (rv != VM_PAGER_OK) 558 panic("vm_thread_swapin: cannot get kstack for proc: %d", 559 td->td_proc->p_pid); 560 vm_object_pip_wakeup(ksobj); 561 for (k = i; k < j; k++) 562 ma[k] = vm_page_lookup(ksobj, k); 563 vm_page_wakeup(ma[i]); 564 } else if (ma[i]->oflags & VPO_BUSY) 565 vm_page_wakeup(ma[i]); 566 } 567 VM_OBJECT_UNLOCK(ksobj); 568 pmap_qenter(td->td_kstack, ma, pages); 569 cpu_thread_swapin(td); 570 } 571 572 /* 573 * Implement fork's actions on an address space. 574 * Here we arrange for the address space to be copied or referenced, 575 * allocate a user struct (pcb and kernel stack), then call the 576 * machine-dependent layer to fill those in and make the new process 577 * ready to run. The new process is set up so that it returns directly 578 * to user mode to avoid stack copying and relocation problems. 579 */ 580 int 581 vm_forkproc(td, p2, td2, vm2, flags) 582 struct thread *td; 583 struct proc *p2; 584 struct thread *td2; 585 struct vmspace *vm2; 586 int flags; 587 { 588 struct proc *p1 = td->td_proc; 589 int error; 590 591 if ((flags & RFPROC) == 0) { 592 /* 593 * Divorce the memory, if it is shared, essentially 594 * this changes shared memory amongst threads, into 595 * COW locally. 596 */ 597 if ((flags & RFMEM) == 0) { 598 if (p1->p_vmspace->vm_refcnt > 1) { 599 error = vmspace_unshare(p1); 600 if (error) 601 return (error); 602 } 603 } 604 cpu_fork(td, p2, td2, flags); 605 return (0); 606 } 607 608 if (flags & RFMEM) { 609 p2->p_vmspace = p1->p_vmspace; 610 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 611 } 612 613 while (vm_page_count_severe()) { 614 VM_WAIT; 615 } 616 617 if ((flags & RFMEM) == 0) { 618 p2->p_vmspace = vm2; 619 if (p1->p_vmspace->vm_shm) 620 shmfork(p1, p2); 621 } 622 623 /* 624 * cpu_fork will copy and update the pcb, set up the kernel stack, 625 * and make the child ready to run. 626 */ 627 cpu_fork(td, p2, td2, flags); 628 return (0); 629 } 630 631 /* 632 * Called after process has been wait(2)'ed apon and is being reaped. 633 * The idea is to reclaim resources that we could not reclaim while 634 * the process was still executing. 635 */ 636 void 637 vm_waitproc(p) 638 struct proc *p; 639 { 640 641 vmspace_exitfree(p); /* and clean-out the vmspace */ 642 } 643 644 /* 645 * Set default limits for VM system. 646 * Called for proc 0, and then inherited by all others. 647 * 648 * XXX should probably act directly on proc0. 649 */ 650 static void 651 vm_init_limits(udata) 652 void *udata; 653 { 654 struct proc *p = udata; 655 struct plimit *limp; 656 int rss_limit; 657 658 /* 659 * Set up the initial limits on process VM. Set the maximum resident 660 * set size to be half of (reasonably) available memory. Since this 661 * is a soft limit, it comes into effect only when the system is out 662 * of memory - half of main memory helps to favor smaller processes, 663 * and reduces thrashing of the object cache. 664 */ 665 limp = p->p_limit; 666 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 667 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 668 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 669 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 670 /* limit the limit to no less than 2MB */ 671 rss_limit = max(cnt.v_free_count, 512); 672 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 673 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 674 } 675 676 void 677 faultin(p) 678 struct proc *p; 679 { 680 #ifdef NO_SWAPPING 681 682 PROC_LOCK_ASSERT(p, MA_OWNED); 683 if ((p->p_flag & P_INMEM) == 0) 684 panic("faultin: proc swapped out with NO_SWAPPING!"); 685 #else /* !NO_SWAPPING */ 686 struct thread *td; 687 688 PROC_LOCK_ASSERT(p, MA_OWNED); 689 /* 690 * If another process is swapping in this process, 691 * just wait until it finishes. 692 */ 693 if (p->p_flag & P_SWAPPINGIN) { 694 while (p->p_flag & P_SWAPPINGIN) 695 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 696 return; 697 } 698 if ((p->p_flag & P_INMEM) == 0) { 699 /* 700 * Don't let another thread swap process p out while we are 701 * busy swapping it in. 702 */ 703 ++p->p_lock; 704 p->p_flag |= P_SWAPPINGIN; 705 PROC_UNLOCK(p); 706 707 /* 708 * We hold no lock here because the list of threads 709 * can not change while all threads in the process are 710 * swapped out. 711 */ 712 FOREACH_THREAD_IN_PROC(p, td) 713 vm_thread_swapin(td); 714 PROC_LOCK(p); 715 swapclear(p); 716 p->p_swtick = ticks; 717 718 wakeup(&p->p_flag); 719 720 /* Allow other threads to swap p out now. */ 721 --p->p_lock; 722 } 723 #endif /* NO_SWAPPING */ 724 } 725 726 /* 727 * This swapin algorithm attempts to swap-in processes only if there 728 * is enough space for them. Of course, if a process waits for a long 729 * time, it will be swapped in anyway. 730 * 731 * Giant is held on entry. 732 */ 733 /* ARGSUSED*/ 734 static void 735 scheduler(dummy) 736 void *dummy; 737 { 738 struct proc *p; 739 struct thread *td; 740 struct proc *pp; 741 int slptime; 742 int swtime; 743 int ppri; 744 int pri; 745 746 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 747 mtx_unlock(&Giant); 748 749 loop: 750 if (vm_page_count_min()) { 751 VM_WAIT; 752 goto loop; 753 } 754 755 pp = NULL; 756 ppri = INT_MIN; 757 sx_slock(&allproc_lock); 758 FOREACH_PROC_IN_SYSTEM(p) { 759 PROC_LOCK(p); 760 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 761 PROC_UNLOCK(p); 762 continue; 763 } 764 swtime = (ticks - p->p_swtick) / hz; 765 FOREACH_THREAD_IN_PROC(p, td) { 766 /* 767 * An otherwise runnable thread of a process 768 * swapped out has only the TDI_SWAPPED bit set. 769 * 770 */ 771 thread_lock(td); 772 if (td->td_inhibitors == TDI_SWAPPED) { 773 slptime = (ticks - td->td_slptick) / hz; 774 pri = swtime + slptime; 775 if ((td->td_flags & TDF_SWAPINREQ) == 0) 776 pri -= p->p_nice * 8; 777 /* 778 * if this thread is higher priority 779 * and there is enough space, then select 780 * this process instead of the previous 781 * selection. 782 */ 783 if (pri > ppri) { 784 pp = p; 785 ppri = pri; 786 } 787 } 788 thread_unlock(td); 789 } 790 PROC_UNLOCK(p); 791 } 792 sx_sunlock(&allproc_lock); 793 794 /* 795 * Nothing to do, back to sleep. 796 */ 797 if ((p = pp) == NULL) { 798 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 799 goto loop; 800 } 801 PROC_LOCK(p); 802 803 /* 804 * Another process may be bringing or may have already 805 * brought this process in while we traverse all threads. 806 * Or, this process may even be being swapped out again. 807 */ 808 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 809 PROC_UNLOCK(p); 810 goto loop; 811 } 812 813 /* 814 * We would like to bring someone in. (only if there is space). 815 * [What checks the space? ] 816 */ 817 faultin(p); 818 PROC_UNLOCK(p); 819 goto loop; 820 } 821 822 void 823 kick_proc0(void) 824 { 825 826 wakeup(&proc0); 827 } 828 829 #ifndef NO_SWAPPING 830 831 /* 832 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 833 */ 834 static int swap_idle_threshold1 = 2; 835 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 836 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 837 838 /* 839 * Swap_idle_threshold2 is the time that a process can be idle before 840 * it will be swapped out, if idle swapping is enabled. 841 */ 842 static int swap_idle_threshold2 = 10; 843 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 844 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 845 846 /* 847 * Swapout is driven by the pageout daemon. Very simple, we find eligible 848 * procs and swap out their stacks. We try to always "swap" at least one 849 * process in case we need the room for a swapin. 850 * If any procs have been sleeping/stopped for at least maxslp seconds, 851 * they are swapped. Else, we swap the longest-sleeping or stopped process, 852 * if any, otherwise the longest-resident process. 853 */ 854 void 855 swapout_procs(action) 856 int action; 857 { 858 struct proc *p; 859 struct thread *td; 860 int didswap = 0; 861 862 retry: 863 sx_slock(&allproc_lock); 864 FOREACH_PROC_IN_SYSTEM(p) { 865 struct vmspace *vm; 866 int minslptime = 100000; 867 int slptime; 868 869 /* 870 * Watch out for a process in 871 * creation. It may have no 872 * address space or lock yet. 873 */ 874 if (p->p_state == PRS_NEW) 875 continue; 876 /* 877 * An aio daemon switches its 878 * address space while running. 879 * Perform a quick check whether 880 * a process has P_SYSTEM. 881 */ 882 if ((p->p_flag & P_SYSTEM) != 0) 883 continue; 884 /* 885 * Do not swapout a process that 886 * is waiting for VM data 887 * structures as there is a possible 888 * deadlock. Test this first as 889 * this may block. 890 * 891 * Lock the map until swapout 892 * finishes, or a thread of this 893 * process may attempt to alter 894 * the map. 895 */ 896 vm = vmspace_acquire_ref(p); 897 if (vm == NULL) 898 continue; 899 if (!vm_map_trylock(&vm->vm_map)) 900 goto nextproc1; 901 902 PROC_LOCK(p); 903 if (p->p_lock != 0 || 904 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 905 ) != 0) { 906 goto nextproc; 907 } 908 /* 909 * only aiod changes vmspace, however it will be 910 * skipped because of the if statement above checking 911 * for P_SYSTEM 912 */ 913 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 914 goto nextproc; 915 916 switch (p->p_state) { 917 default: 918 /* Don't swap out processes in any sort 919 * of 'special' state. */ 920 break; 921 922 case PRS_NORMAL: 923 /* 924 * do not swapout a realtime process 925 * Check all the thread groups.. 926 */ 927 FOREACH_THREAD_IN_PROC(p, td) { 928 thread_lock(td); 929 if (PRI_IS_REALTIME(td->td_pri_class)) { 930 thread_unlock(td); 931 goto nextproc; 932 } 933 slptime = (ticks - td->td_slptick) / hz; 934 /* 935 * Guarantee swap_idle_threshold1 936 * time in memory. 937 */ 938 if (slptime < swap_idle_threshold1) { 939 thread_unlock(td); 940 goto nextproc; 941 } 942 943 /* 944 * Do not swapout a process if it is 945 * waiting on a critical event of some 946 * kind or there is a thread whose 947 * pageable memory may be accessed. 948 * 949 * This could be refined to support 950 * swapping out a thread. 951 */ 952 if (!thread_safetoswapout(td)) { 953 thread_unlock(td); 954 goto nextproc; 955 } 956 /* 957 * If the system is under memory stress, 958 * or if we are swapping 959 * idle processes >= swap_idle_threshold2, 960 * then swap the process out. 961 */ 962 if (((action & VM_SWAP_NORMAL) == 0) && 963 (((action & VM_SWAP_IDLE) == 0) || 964 (slptime < swap_idle_threshold2))) { 965 thread_unlock(td); 966 goto nextproc; 967 } 968 969 if (minslptime > slptime) 970 minslptime = slptime; 971 thread_unlock(td); 972 } 973 974 /* 975 * If the pageout daemon didn't free enough pages, 976 * or if this process is idle and the system is 977 * configured to swap proactively, swap it out. 978 */ 979 if ((action & VM_SWAP_NORMAL) || 980 ((action & VM_SWAP_IDLE) && 981 (minslptime > swap_idle_threshold2))) { 982 if (swapout(p) == 0) 983 didswap++; 984 PROC_UNLOCK(p); 985 vm_map_unlock(&vm->vm_map); 986 vmspace_free(vm); 987 sx_sunlock(&allproc_lock); 988 goto retry; 989 } 990 } 991 nextproc: 992 PROC_UNLOCK(p); 993 vm_map_unlock(&vm->vm_map); 994 nextproc1: 995 vmspace_free(vm); 996 continue; 997 } 998 sx_sunlock(&allproc_lock); 999 /* 1000 * If we swapped something out, and another process needed memory, 1001 * then wakeup the sched process. 1002 */ 1003 if (didswap) 1004 wakeup(&proc0); 1005 } 1006 1007 static void 1008 swapclear(p) 1009 struct proc *p; 1010 { 1011 struct thread *td; 1012 1013 PROC_LOCK_ASSERT(p, MA_OWNED); 1014 1015 FOREACH_THREAD_IN_PROC(p, td) { 1016 thread_lock(td); 1017 td->td_flags |= TDF_INMEM; 1018 td->td_flags &= ~TDF_SWAPINREQ; 1019 TD_CLR_SWAPPED(td); 1020 if (TD_CAN_RUN(td)) 1021 if (setrunnable(td)) { 1022 #ifdef INVARIANTS 1023 /* 1024 * XXX: We just cleared TDI_SWAPPED 1025 * above and set TDF_INMEM, so this 1026 * should never happen. 1027 */ 1028 panic("not waking up swapper"); 1029 #endif 1030 } 1031 thread_unlock(td); 1032 } 1033 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 1034 p->p_flag |= P_INMEM; 1035 } 1036 1037 static int 1038 swapout(p) 1039 struct proc *p; 1040 { 1041 struct thread *td; 1042 1043 PROC_LOCK_ASSERT(p, MA_OWNED); 1044 #if defined(SWAP_DEBUG) 1045 printf("swapping out %d\n", p->p_pid); 1046 #endif 1047 1048 /* 1049 * The states of this process and its threads may have changed 1050 * by now. Assuming that there is only one pageout daemon thread, 1051 * this process should still be in memory. 1052 */ 1053 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1054 ("swapout: lost a swapout race?")); 1055 1056 /* 1057 * remember the process resident count 1058 */ 1059 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1060 /* 1061 * Check and mark all threads before we proceed. 1062 */ 1063 p->p_flag &= ~P_INMEM; 1064 p->p_flag |= P_SWAPPINGOUT; 1065 FOREACH_THREAD_IN_PROC(p, td) { 1066 thread_lock(td); 1067 if (!thread_safetoswapout(td)) { 1068 thread_unlock(td); 1069 swapclear(p); 1070 return (EBUSY); 1071 } 1072 td->td_flags &= ~TDF_INMEM; 1073 TD_SET_SWAPPED(td); 1074 thread_unlock(td); 1075 } 1076 td = FIRST_THREAD_IN_PROC(p); 1077 ++td->td_ru.ru_nswap; 1078 PROC_UNLOCK(p); 1079 1080 /* 1081 * This list is stable because all threads are now prevented from 1082 * running. The list is only modified in the context of a running 1083 * thread in this process. 1084 */ 1085 FOREACH_THREAD_IN_PROC(p, td) 1086 vm_thread_swapout(td); 1087 1088 PROC_LOCK(p); 1089 p->p_flag &= ~P_SWAPPINGOUT; 1090 p->p_swtick = ticks; 1091 return (0); 1092 } 1093 #endif /* !NO_SWAPPING */
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