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/kernel.h> 81 #include <sys/ktr.h> 82 #include <sys/unistd.h> 83 84 #include <vm/vm.h> 85 #include <vm/vm_param.h> 86 #include <vm/pmap.h> 87 #include <vm/vm_map.h> 88 #include <vm/vm_page.h> 89 #include <vm/vm_pageout.h> 90 #include <vm/vm_object.h> 91 #include <vm/vm_kern.h> 92 #include <vm/vm_extern.h> 93 #include <vm/vm_pager.h> 94 #include <vm/swap_pager.h> 95 96 extern int maxslp; 97 98 /* 99 * System initialization 100 * 101 * Note: proc0 from proc.h 102 */ 103 static void vm_init_limits(void *); 104 SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0); 105 106 /* 107 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 108 * 109 * Note: run scheduling should be divorced from the vm system. 110 */ 111 static void scheduler(void *); 112 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL); 113 114 #ifndef NO_SWAPPING 115 static int swapout(struct proc *); 116 static void swapclear(struct proc *); 117 #endif 118 119 120 static volatile int proc0_rescan; 121 122 123 /* 124 * MPSAFE 125 * 126 * WARNING! This code calls vm_map_check_protection() which only checks 127 * the associated vm_map_entry range. It does not determine whether the 128 * contents of the memory is actually readable or writable. In most cases 129 * just checking the vm_map_entry is sufficient within the kernel's address 130 * space. 131 */ 132 int 133 kernacc(addr, len, rw) 134 void *addr; 135 int len, rw; 136 { 137 boolean_t rv; 138 vm_offset_t saddr, eaddr; 139 vm_prot_t prot; 140 141 KASSERT((rw & ~VM_PROT_ALL) == 0, 142 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 143 144 if ((vm_offset_t)addr + len > kernel_map->max_offset || 145 (vm_offset_t)addr + len < (vm_offset_t)addr) 146 return (FALSE); 147 148 prot = rw; 149 saddr = trunc_page((vm_offset_t)addr); 150 eaddr = round_page((vm_offset_t)addr + len); 151 vm_map_lock_read(kernel_map); 152 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 153 vm_map_unlock_read(kernel_map); 154 return (rv == TRUE); 155 } 156 157 /* 158 * MPSAFE 159 * 160 * WARNING! This code calls vm_map_check_protection() which only checks 161 * the associated vm_map_entry range. It does not determine whether the 162 * contents of the memory is actually readable or writable. vmapbuf(), 163 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 164 * used in conjuction with this call. 165 */ 166 int 167 useracc(addr, len, rw) 168 void *addr; 169 int len, rw; 170 { 171 boolean_t rv; 172 vm_prot_t prot; 173 vm_map_t map; 174 175 KASSERT((rw & ~VM_PROT_ALL) == 0, 176 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 177 prot = rw; 178 map = &curproc->p_vmspace->vm_map; 179 if ((vm_offset_t)addr + len > vm_map_max(map) || 180 (vm_offset_t)addr + len < (vm_offset_t)addr) { 181 return (FALSE); 182 } 183 vm_map_lock_read(map); 184 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 185 round_page((vm_offset_t)addr + len), prot); 186 vm_map_unlock_read(map); 187 return (rv == TRUE); 188 } 189 190 int 191 vslock(void *addr, size_t len) 192 { 193 vm_offset_t end, last, start; 194 vm_size_t npages; 195 int error; 196 197 last = (vm_offset_t)addr + len; 198 start = trunc_page((vm_offset_t)addr); 199 end = round_page(last); 200 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 201 return (EINVAL); 202 npages = atop(end - start); 203 if (npages > vm_page_max_wired) 204 return (ENOMEM); 205 PROC_LOCK(curproc); 206 if (ptoa(npages + 207 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 208 lim_cur(curproc, RLIMIT_MEMLOCK)) { 209 PROC_UNLOCK(curproc); 210 return (ENOMEM); 211 } 212 PROC_UNLOCK(curproc); 213 #if 0 214 /* 215 * XXX - not yet 216 * 217 * The limit for transient usage of wired pages should be 218 * larger than for "permanent" wired pages (mlock()). 219 * 220 * Also, the sysctl code, which is the only present user 221 * of vslock(), does a hard loop on EAGAIN. 222 */ 223 if (npages + cnt.v_wire_count > vm_page_max_wired) 224 return (EAGAIN); 225 #endif 226 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 227 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 228 /* 229 * Return EFAULT on error to match copy{in,out}() behaviour 230 * rather than returning ENOMEM like mlock() would. 231 */ 232 return (error == KERN_SUCCESS ? 0 : EFAULT); 233 } 234 235 void 236 vsunlock(void *addr, size_t len) 237 { 238 239 /* Rely on the parameter sanity checks performed by vslock(). */ 240 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 241 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 242 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 243 } 244 245 /* 246 * Pin the page contained within the given object at the given offset. If the 247 * page is not resident, allocate and load it using the given object's pager. 248 * Return the pinned page if successful; otherwise, return NULL. 249 */ 250 static vm_page_t 251 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 252 { 253 vm_page_t m, ma[1]; 254 vm_pindex_t pindex; 255 int rv; 256 257 VM_OBJECT_LOCK(object); 258 pindex = OFF_TO_IDX(offset); 259 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 260 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 261 ma[0] = m; 262 rv = vm_pager_get_pages(object, ma, 1, 0); 263 m = vm_page_lookup(object, pindex); 264 if (m == NULL) 265 goto out; 266 if (m->valid == 0 || rv != VM_PAGER_OK) { 267 vm_page_lock_queues(); 268 vm_page_free(m); 269 vm_page_unlock_queues(); 270 m = NULL; 271 goto out; 272 } 273 } 274 vm_page_lock_queues(); 275 vm_page_hold(m); 276 vm_page_unlock_queues(); 277 vm_page_wakeup(m); 278 out: 279 VM_OBJECT_UNLOCK(object); 280 return (m); 281 } 282 283 /* 284 * Return a CPU private mapping to the page at the given offset within the 285 * given object. The page is pinned before it is mapped. 286 */ 287 struct sf_buf * 288 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 289 { 290 vm_page_t m; 291 292 m = vm_imgact_hold_page(object, offset); 293 if (m == NULL) 294 return (NULL); 295 sched_pin(); 296 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 297 } 298 299 /* 300 * Destroy the given CPU private mapping and unpin the page that it mapped. 301 */ 302 void 303 vm_imgact_unmap_page(struct sf_buf *sf) 304 { 305 vm_page_t m; 306 307 m = sf_buf_page(sf); 308 sf_buf_free(sf); 309 sched_unpin(); 310 vm_page_lock_queues(); 311 vm_page_unhold(m); 312 vm_page_unlock_queues(); 313 } 314 315 #ifndef KSTACK_MAX_PAGES 316 #define KSTACK_MAX_PAGES 32 317 #endif 318 319 /* 320 * Create the kernel stack (including pcb for i386) for a new thread. 321 * This routine directly affects the fork perf for a process and 322 * create performance for a thread. 323 */ 324 int 325 vm_thread_new(struct thread *td, int pages) 326 { 327 vm_object_t ksobj; 328 vm_offset_t ks; 329 vm_page_t m, ma[KSTACK_MAX_PAGES]; 330 int i; 331 332 /* Bounds check */ 333 if (pages <= 1) 334 pages = KSTACK_PAGES; 335 else if (pages > KSTACK_MAX_PAGES) 336 pages = KSTACK_MAX_PAGES; 337 /* 338 * Allocate an object for the kstack. 339 */ 340 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 341 342 /* 343 * Get a kernel virtual address for this thread's kstack. 344 */ 345 ks = kmem_alloc_nofault(kernel_map, 346 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 347 if (ks == 0) { 348 printf("vm_thread_new: kstack allocation failed\n"); 349 vm_object_deallocate(ksobj); 350 return (0); 351 } 352 353 if (KSTACK_GUARD_PAGES != 0) { 354 pmap_qremove(ks, KSTACK_GUARD_PAGES); 355 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 356 } 357 td->td_kstack_obj = ksobj; 358 td->td_kstack = ks; 359 /* 360 * Knowing the number of pages allocated is useful when you 361 * want to deallocate them. 362 */ 363 td->td_kstack_pages = pages; 364 /* 365 * For the length of the stack, link in a real page of ram for each 366 * page of stack. 367 */ 368 VM_OBJECT_LOCK(ksobj); 369 for (i = 0; i < pages; i++) { 370 /* 371 * Get a kernel stack page. 372 */ 373 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 374 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 375 ma[i] = m; 376 m->valid = VM_PAGE_BITS_ALL; 377 } 378 VM_OBJECT_UNLOCK(ksobj); 379 pmap_qenter(ks, ma, pages); 380 return (1); 381 } 382 383 /* 384 * Dispose of a thread's kernel stack. 385 */ 386 void 387 vm_thread_dispose(struct thread *td) 388 { 389 vm_object_t ksobj; 390 vm_offset_t ks; 391 vm_page_t m; 392 int i, pages; 393 394 pages = td->td_kstack_pages; 395 ksobj = td->td_kstack_obj; 396 ks = td->td_kstack; 397 pmap_qremove(ks, pages); 398 VM_OBJECT_LOCK(ksobj); 399 for (i = 0; i < pages; i++) { 400 m = vm_page_lookup(ksobj, i); 401 if (m == NULL) 402 panic("vm_thread_dispose: kstack already missing?"); 403 vm_page_lock_queues(); 404 vm_page_unwire(m, 0); 405 vm_page_free(m); 406 vm_page_unlock_queues(); 407 } 408 VM_OBJECT_UNLOCK(ksobj); 409 vm_object_deallocate(ksobj); 410 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 411 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 412 td->td_kstack = 0; 413 } 414 415 /* 416 * Allow a thread's kernel stack to be paged out. 417 */ 418 void 419 vm_thread_swapout(struct thread *td) 420 { 421 vm_object_t ksobj; 422 vm_page_t m; 423 int i, pages; 424 425 cpu_thread_swapout(td); 426 pages = td->td_kstack_pages; 427 ksobj = td->td_kstack_obj; 428 pmap_qremove(td->td_kstack, pages); 429 VM_OBJECT_LOCK(ksobj); 430 for (i = 0; i < pages; i++) { 431 m = vm_page_lookup(ksobj, i); 432 if (m == NULL) 433 panic("vm_thread_swapout: kstack already missing?"); 434 vm_page_lock_queues(); 435 vm_page_dirty(m); 436 vm_page_unwire(m, 0); 437 vm_page_unlock_queues(); 438 } 439 VM_OBJECT_UNLOCK(ksobj); 440 } 441 442 /* 443 * Bring the kernel stack for a specified thread back in. 444 */ 445 void 446 vm_thread_swapin(struct thread *td) 447 { 448 vm_object_t ksobj; 449 vm_page_t m, ma[KSTACK_MAX_PAGES]; 450 int i, pages, rv; 451 452 pages = td->td_kstack_pages; 453 ksobj = td->td_kstack_obj; 454 VM_OBJECT_LOCK(ksobj); 455 for (i = 0; i < pages; i++) { 456 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 457 if (m->valid != VM_PAGE_BITS_ALL) { 458 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 459 if (rv != VM_PAGER_OK) 460 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 461 m = vm_page_lookup(ksobj, i); 462 m->valid = VM_PAGE_BITS_ALL; 463 } 464 ma[i] = m; 465 vm_page_lock_queues(); 466 vm_page_wire(m); 467 vm_page_unlock_queues(); 468 vm_page_wakeup(m); 469 } 470 VM_OBJECT_UNLOCK(ksobj); 471 pmap_qenter(td->td_kstack, ma, pages); 472 cpu_thread_swapin(td); 473 } 474 475 /* 476 * Set up a variable-sized alternate kstack. 477 */ 478 int 479 vm_thread_new_altkstack(struct thread *td, int pages) 480 { 481 482 td->td_altkstack = td->td_kstack; 483 td->td_altkstack_obj = td->td_kstack_obj; 484 td->td_altkstack_pages = td->td_kstack_pages; 485 486 return (vm_thread_new(td, pages)); 487 } 488 489 /* 490 * Restore the original kstack. 491 */ 492 void 493 vm_thread_dispose_altkstack(struct thread *td) 494 { 495 496 vm_thread_dispose(td); 497 498 td->td_kstack = td->td_altkstack; 499 td->td_kstack_obj = td->td_altkstack_obj; 500 td->td_kstack_pages = td->td_altkstack_pages; 501 td->td_altkstack = 0; 502 td->td_altkstack_obj = NULL; 503 td->td_altkstack_pages = 0; 504 } 505 506 /* 507 * Implement fork's actions on an address space. 508 * Here we arrange for the address space to be copied or referenced, 509 * allocate a user struct (pcb and kernel stack), then call the 510 * machine-dependent layer to fill those in and make the new process 511 * ready to run. The new process is set up so that it returns directly 512 * to user mode to avoid stack copying and relocation problems. 513 */ 514 int 515 vm_forkproc(td, p2, td2, vm2, flags) 516 struct thread *td; 517 struct proc *p2; 518 struct thread *td2; 519 struct vmspace *vm2; 520 int flags; 521 { 522 struct proc *p1 = td->td_proc; 523 int error; 524 525 if ((flags & RFPROC) == 0) { 526 /* 527 * Divorce the memory, if it is shared, essentially 528 * this changes shared memory amongst threads, into 529 * COW locally. 530 */ 531 if ((flags & RFMEM) == 0) { 532 if (p1->p_vmspace->vm_refcnt > 1) { 533 error = vmspace_unshare(p1); 534 if (error) 535 return (error); 536 } 537 } 538 cpu_fork(td, p2, td2, flags); 539 return (0); 540 } 541 542 if (flags & RFMEM) { 543 p2->p_vmspace = p1->p_vmspace; 544 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 545 } 546 547 while (vm_page_count_severe()) { 548 VM_WAIT; 549 } 550 551 if ((flags & RFMEM) == 0) { 552 p2->p_vmspace = vm2; 553 if (p1->p_vmspace->vm_shm) 554 shmfork(p1, p2); 555 } 556 557 /* 558 * cpu_fork will copy and update the pcb, set up the kernel stack, 559 * and make the child ready to run. 560 */ 561 cpu_fork(td, p2, td2, flags); 562 return (0); 563 } 564 565 /* 566 * Called after process has been wait(2)'ed apon and is being reaped. 567 * The idea is to reclaim resources that we could not reclaim while 568 * the process was still executing. 569 */ 570 void 571 vm_waitproc(p) 572 struct proc *p; 573 { 574 575 vmspace_exitfree(p); /* and clean-out the vmspace */ 576 } 577 578 /* 579 * Set default limits for VM system. 580 * Called for proc 0, and then inherited by all others. 581 * 582 * XXX should probably act directly on proc0. 583 */ 584 static void 585 vm_init_limits(udata) 586 void *udata; 587 { 588 struct proc *p = udata; 589 struct plimit *limp; 590 int rss_limit; 591 592 /* 593 * Set up the initial limits on process VM. Set the maximum resident 594 * set size to be half of (reasonably) available memory. Since this 595 * is a soft limit, it comes into effect only when the system is out 596 * of memory - half of main memory helps to favor smaller processes, 597 * and reduces thrashing of the object cache. 598 */ 599 limp = p->p_limit; 600 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 601 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 602 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 603 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 604 /* limit the limit to no less than 2MB */ 605 rss_limit = max(cnt.v_free_count, 512); 606 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 607 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 608 } 609 610 void 611 faultin(p) 612 struct proc *p; 613 { 614 #ifdef NO_SWAPPING 615 616 PROC_LOCK_ASSERT(p, MA_OWNED); 617 if ((p->p_flag & P_INMEM) == 0) 618 panic("faultin: proc swapped out with NO_SWAPPING!"); 619 #else /* !NO_SWAPPING */ 620 struct thread *td; 621 622 PROC_LOCK_ASSERT(p, MA_OWNED); 623 /* 624 * If another process is swapping in this process, 625 * just wait until it finishes. 626 */ 627 if (p->p_flag & P_SWAPPINGIN) { 628 while (p->p_flag & P_SWAPPINGIN) 629 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 630 return; 631 } 632 if ((p->p_flag & P_INMEM) == 0) { 633 /* 634 * Don't let another thread swap process p out while we are 635 * busy swapping it in. 636 */ 637 ++p->p_lock; 638 p->p_flag |= P_SWAPPINGIN; 639 PROC_UNLOCK(p); 640 641 /* 642 * We hold no lock here because the list of threads 643 * can not change while all threads in the process are 644 * swapped out. 645 */ 646 FOREACH_THREAD_IN_PROC(p, td) 647 vm_thread_swapin(td); 648 PROC_LOCK(p); 649 swapclear(p); 650 p->p_swtick = ticks; 651 652 wakeup(&p->p_flag); 653 654 /* Allow other threads to swap p out now. */ 655 --p->p_lock; 656 } 657 #endif /* NO_SWAPPING */ 658 } 659 660 /* 661 * This swapin algorithm attempts to swap-in processes only if there 662 * is enough space for them. Of course, if a process waits for a long 663 * time, it will be swapped in anyway. 664 * 665 * Giant is held on entry. 666 */ 667 /* ARGSUSED*/ 668 static void 669 scheduler(dummy) 670 void *dummy; 671 { 672 struct proc *p; 673 struct thread *td; 674 struct proc *pp; 675 int slptime; 676 int swtime; 677 int ppri; 678 int pri; 679 680 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 681 mtx_unlock(&Giant); 682 683 loop: 684 if (vm_page_count_min()) { 685 VM_WAIT; 686 thread_lock(&thread0); 687 proc0_rescan = 0; 688 thread_unlock(&thread0); 689 goto loop; 690 } 691 692 pp = NULL; 693 ppri = INT_MIN; 694 sx_slock(&allproc_lock); 695 FOREACH_PROC_IN_SYSTEM(p) { 696 PROC_LOCK(p); 697 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 698 PROC_UNLOCK(p); 699 continue; 700 } 701 swtime = (ticks - p->p_swtick) / hz; 702 FOREACH_THREAD_IN_PROC(p, td) { 703 /* 704 * An otherwise runnable thread of a process 705 * swapped out has only the TDI_SWAPPED bit set. 706 * 707 */ 708 thread_lock(td); 709 if (td->td_inhibitors == TDI_SWAPPED) { 710 slptime = (ticks - td->td_slptick) / hz; 711 pri = swtime + slptime; 712 if ((td->td_flags & TDF_SWAPINREQ) == 0) 713 pri -= p->p_nice * 8; 714 /* 715 * if this thread is higher priority 716 * and there is enough space, then select 717 * this process instead of the previous 718 * selection. 719 */ 720 if (pri > ppri) { 721 pp = p; 722 ppri = pri; 723 } 724 } 725 thread_unlock(td); 726 } 727 PROC_UNLOCK(p); 728 } 729 sx_sunlock(&allproc_lock); 730 731 /* 732 * Nothing to do, back to sleep. 733 */ 734 if ((p = pp) == NULL) { 735 thread_lock(&thread0); 736 if (!proc0_rescan) { 737 TD_SET_IWAIT(&thread0); 738 mi_switch(SW_VOL | SWT_IWAIT, NULL); 739 } 740 proc0_rescan = 0; 741 thread_unlock(&thread0); 742 goto loop; 743 } 744 PROC_LOCK(p); 745 746 /* 747 * Another process may be bringing or may have already 748 * brought this process in while we traverse all threads. 749 * Or, this process may even be being swapped out again. 750 */ 751 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 752 PROC_UNLOCK(p); 753 thread_lock(&thread0); 754 proc0_rescan = 0; 755 thread_unlock(&thread0); 756 goto loop; 757 } 758 759 /* 760 * We would like to bring someone in. (only if there is space). 761 * [What checks the space? ] 762 */ 763 faultin(p); 764 PROC_UNLOCK(p); 765 thread_lock(&thread0); 766 proc0_rescan = 0; 767 thread_unlock(&thread0); 768 goto loop; 769 } 770 771 void kick_proc0(void) 772 { 773 struct thread *td = &thread0; 774 775 /* XXX This will probably cause a LOR in some cases */ 776 thread_lock(td); 777 if (TD_AWAITING_INTR(td)) { 778 CTR2(KTR_INTR, "%s: sched_add %d", __func__, 0); 779 TD_CLR_IWAIT(td); 780 sched_add(td, SRQ_INTR); 781 } else { 782 proc0_rescan = 1; 783 CTR2(KTR_INTR, "%s: state %d", 784 __func__, td->td_state); 785 } 786 thread_unlock(td); 787 788 } 789 790 791 #ifndef NO_SWAPPING 792 793 /* 794 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 795 */ 796 static int swap_idle_threshold1 = 2; 797 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 798 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 799 800 /* 801 * Swap_idle_threshold2 is the time that a process can be idle before 802 * it will be swapped out, if idle swapping is enabled. 803 */ 804 static int swap_idle_threshold2 = 10; 805 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 806 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 807 808 /* 809 * Swapout is driven by the pageout daemon. Very simple, we find eligible 810 * procs and swap out their stacks. We try to always "swap" at least one 811 * process in case we need the room for a swapin. 812 * If any procs have been sleeping/stopped for at least maxslp seconds, 813 * they are swapped. Else, we swap the longest-sleeping or stopped process, 814 * if any, otherwise the longest-resident process. 815 */ 816 void 817 swapout_procs(action) 818 int action; 819 { 820 struct proc *p; 821 struct thread *td; 822 int didswap = 0; 823 824 retry: 825 sx_slock(&allproc_lock); 826 FOREACH_PROC_IN_SYSTEM(p) { 827 struct vmspace *vm; 828 int minslptime = 100000; 829 int slptime; 830 831 /* 832 * Watch out for a process in 833 * creation. It may have no 834 * address space or lock yet. 835 */ 836 if (p->p_state == PRS_NEW) 837 continue; 838 /* 839 * An aio daemon switches its 840 * address space while running. 841 * Perform a quick check whether 842 * a process has P_SYSTEM. 843 */ 844 if ((p->p_flag & P_SYSTEM) != 0) 845 continue; 846 /* 847 * Do not swapout a process that 848 * is waiting for VM data 849 * structures as there is a possible 850 * deadlock. Test this first as 851 * this may block. 852 * 853 * Lock the map until swapout 854 * finishes, or a thread of this 855 * process may attempt to alter 856 * the map. 857 */ 858 vm = vmspace_acquire_ref(p); 859 if (vm == NULL) 860 continue; 861 if (!vm_map_trylock(&vm->vm_map)) 862 goto nextproc1; 863 864 PROC_LOCK(p); 865 if (p->p_lock != 0 || 866 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 867 ) != 0) { 868 goto nextproc; 869 } 870 /* 871 * only aiod changes vmspace, however it will be 872 * skipped because of the if statement above checking 873 * for P_SYSTEM 874 */ 875 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 876 goto nextproc; 877 878 switch (p->p_state) { 879 default: 880 /* Don't swap out processes in any sort 881 * of 'special' state. */ 882 break; 883 884 case PRS_NORMAL: 885 /* 886 * do not swapout a realtime process 887 * Check all the thread groups.. 888 */ 889 FOREACH_THREAD_IN_PROC(p, td) { 890 thread_lock(td); 891 if (PRI_IS_REALTIME(td->td_pri_class)) { 892 thread_unlock(td); 893 goto nextproc; 894 } 895 slptime = (ticks - td->td_slptick) / hz; 896 /* 897 * Guarantee swap_idle_threshold1 898 * time in memory. 899 */ 900 if (slptime < swap_idle_threshold1) { 901 thread_unlock(td); 902 goto nextproc; 903 } 904 905 /* 906 * Do not swapout a process if it is 907 * waiting on a critical event of some 908 * kind or there is a thread whose 909 * pageable memory may be accessed. 910 * 911 * This could be refined to support 912 * swapping out a thread. 913 */ 914 if (!thread_safetoswapout(td)) { 915 thread_unlock(td); 916 goto nextproc; 917 } 918 /* 919 * If the system is under memory stress, 920 * or if we are swapping 921 * idle processes >= swap_idle_threshold2, 922 * then swap the process out. 923 */ 924 if (((action & VM_SWAP_NORMAL) == 0) && 925 (((action & VM_SWAP_IDLE) == 0) || 926 (slptime < swap_idle_threshold2))) { 927 thread_unlock(td); 928 goto nextproc; 929 } 930 931 if (minslptime > slptime) 932 minslptime = slptime; 933 thread_unlock(td); 934 } 935 936 /* 937 * If the pageout daemon didn't free enough pages, 938 * or if this process is idle and the system is 939 * configured to swap proactively, swap it out. 940 */ 941 if ((action & VM_SWAP_NORMAL) || 942 ((action & VM_SWAP_IDLE) && 943 (minslptime > swap_idle_threshold2))) { 944 if (swapout(p) == 0) 945 didswap++; 946 PROC_UNLOCK(p); 947 vm_map_unlock(&vm->vm_map); 948 vmspace_free(vm); 949 sx_sunlock(&allproc_lock); 950 goto retry; 951 } 952 } 953 nextproc: 954 PROC_UNLOCK(p); 955 vm_map_unlock(&vm->vm_map); 956 nextproc1: 957 vmspace_free(vm); 958 continue; 959 } 960 sx_sunlock(&allproc_lock); 961 /* 962 * If we swapped something out, and another process needed memory, 963 * then wakeup the sched process. 964 */ 965 if (didswap) 966 wakeup(&proc0); 967 } 968 969 static void 970 swapclear(p) 971 struct proc *p; 972 { 973 struct thread *td; 974 975 PROC_LOCK_ASSERT(p, MA_OWNED); 976 977 FOREACH_THREAD_IN_PROC(p, td) { 978 thread_lock(td); 979 td->td_flags |= TDF_INMEM; 980 td->td_flags &= ~TDF_SWAPINREQ; 981 TD_CLR_SWAPPED(td); 982 if (TD_CAN_RUN(td)) 983 setrunnable(td); 984 thread_unlock(td); 985 } 986 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 987 p->p_flag |= P_INMEM; 988 } 989 990 static int 991 swapout(p) 992 struct proc *p; 993 { 994 struct thread *td; 995 996 PROC_LOCK_ASSERT(p, MA_OWNED); 997 #if defined(SWAP_DEBUG) 998 printf("swapping out %d\n", p->p_pid); 999 #endif 1000 1001 /* 1002 * The states of this process and its threads may have changed 1003 * by now. Assuming that there is only one pageout daemon thread, 1004 * this process should still be in memory. 1005 */ 1006 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1007 ("swapout: lost a swapout race?")); 1008 1009 /* 1010 * remember the process resident count 1011 */ 1012 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1013 /* 1014 * Check and mark all threads before we proceed. 1015 */ 1016 p->p_flag &= ~P_INMEM; 1017 p->p_flag |= P_SWAPPINGOUT; 1018 FOREACH_THREAD_IN_PROC(p, td) { 1019 thread_lock(td); 1020 if (!thread_safetoswapout(td)) { 1021 thread_unlock(td); 1022 swapclear(p); 1023 return (EBUSY); 1024 } 1025 td->td_flags &= ~TDF_INMEM; 1026 TD_SET_SWAPPED(td); 1027 thread_unlock(td); 1028 } 1029 td = FIRST_THREAD_IN_PROC(p); 1030 ++td->td_ru.ru_nswap; 1031 PROC_UNLOCK(p); 1032 1033 /* 1034 * This list is stable because all threads are now prevented from 1035 * running. The list is only modified in the context of a running 1036 * thread in this process. 1037 */ 1038 FOREACH_THREAD_IN_PROC(p, td) 1039 vm_thread_swapout(td); 1040 1041 PROC_LOCK(p); 1042 p->p_flag &= ~P_SWAPPINGOUT; 1043 p->p_swtick = ticks; 1044 return (0); 1045 } 1046 #endif /* !NO_SWAPPING */ 1047