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("$FreeBSD$"); 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 * Get a kernel virtual address for this thread's kstack. 343 */ 344 ks = kmem_alloc_nofault(kernel_map, 345 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 346 if (ks == 0) { 347 printf("vm_thread_new: kstack allocation failed\n"); 348 vm_object_deallocate(ksobj); 349 return (0); 350 } 351 352 if (KSTACK_GUARD_PAGES != 0) { 353 pmap_qremove(ks, KSTACK_GUARD_PAGES); 354 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 355 } 356 td->td_kstack_obj = ksobj; 357 td->td_kstack = ks; 358 /* 359 * Knowing the number of pages allocated is useful when you 360 * want to deallocate them. 361 */ 362 td->td_kstack_pages = pages; 363 /* 364 * For the length of the stack, link in a real page of ram for each 365 * page of stack. 366 */ 367 VM_OBJECT_LOCK(ksobj); 368 for (i = 0; i < pages; i++) { 369 /* 370 * Get a kernel stack page. 371 */ 372 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 373 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 374 ma[i] = m; 375 m->valid = VM_PAGE_BITS_ALL; 376 } 377 VM_OBJECT_UNLOCK(ksobj); 378 pmap_qenter(ks, ma, pages); 379 return (1); 380 } 381 382 /* 383 * Dispose of a thread's kernel stack. 384 */ 385 void 386 vm_thread_dispose(struct thread *td) 387 { 388 vm_object_t ksobj; 389 vm_offset_t ks; 390 vm_page_t m; 391 int i, pages; 392 393 pages = td->td_kstack_pages; 394 ksobj = td->td_kstack_obj; 395 ks = td->td_kstack; 396 pmap_qremove(ks, pages); 397 VM_OBJECT_LOCK(ksobj); 398 for (i = 0; i < pages; i++) { 399 m = vm_page_lookup(ksobj, i); 400 if (m == NULL) 401 panic("vm_thread_dispose: kstack already missing?"); 402 vm_page_lock_queues(); 403 vm_page_unwire(m, 0); 404 vm_page_free(m); 405 vm_page_unlock_queues(); 406 } 407 VM_OBJECT_UNLOCK(ksobj); 408 vm_object_deallocate(ksobj); 409 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 410 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 411 td->td_kstack = 0; 412 } 413 414 /* 415 * Allow a thread's kernel stack to be paged out. 416 */ 417 void 418 vm_thread_swapout(struct thread *td) 419 { 420 vm_object_t ksobj; 421 vm_page_t m; 422 int i, pages; 423 424 cpu_thread_swapout(td); 425 pages = td->td_kstack_pages; 426 ksobj = td->td_kstack_obj; 427 pmap_qremove(td->td_kstack, pages); 428 VM_OBJECT_LOCK(ksobj); 429 for (i = 0; i < pages; i++) { 430 m = vm_page_lookup(ksobj, i); 431 if (m == NULL) 432 panic("vm_thread_swapout: kstack already missing?"); 433 vm_page_lock_queues(); 434 vm_page_dirty(m); 435 vm_page_unwire(m, 0); 436 vm_page_unlock_queues(); 437 } 438 VM_OBJECT_UNLOCK(ksobj); 439 } 440 441 /* 442 * Bring the kernel stack for a specified thread back in. 443 */ 444 void 445 vm_thread_swapin(struct thread *td) 446 { 447 vm_object_t ksobj; 448 vm_page_t m, ma[KSTACK_MAX_PAGES]; 449 int i, pages, rv; 450 451 pages = td->td_kstack_pages; 452 ksobj = td->td_kstack_obj; 453 VM_OBJECT_LOCK(ksobj); 454 for (i = 0; i < pages; i++) { 455 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 456 if (m->valid != VM_PAGE_BITS_ALL) { 457 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 458 if (rv != VM_PAGER_OK) 459 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 460 m = vm_page_lookup(ksobj, i); 461 m->valid = VM_PAGE_BITS_ALL; 462 } 463 ma[i] = m; 464 vm_page_lock_queues(); 465 vm_page_wire(m); 466 vm_page_unlock_queues(); 467 vm_page_wakeup(m); 468 } 469 VM_OBJECT_UNLOCK(ksobj); 470 pmap_qenter(td->td_kstack, ma, pages); 471 cpu_thread_swapin(td); 472 } 473 474 /* 475 * Set up a variable-sized alternate kstack. 476 */ 477 int 478 vm_thread_new_altkstack(struct thread *td, int pages) 479 { 480 481 td->td_altkstack = td->td_kstack; 482 td->td_altkstack_obj = td->td_kstack_obj; 483 td->td_altkstack_pages = td->td_kstack_pages; 484 485 return (vm_thread_new(td, pages)); 486 } 487 488 /* 489 * Restore the original kstack. 490 */ 491 void 492 vm_thread_dispose_altkstack(struct thread *td) 493 { 494 495 vm_thread_dispose(td); 496 497 td->td_kstack = td->td_altkstack; 498 td->td_kstack_obj = td->td_altkstack_obj; 499 td->td_kstack_pages = td->td_altkstack_pages; 500 td->td_altkstack = 0; 501 td->td_altkstack_obj = NULL; 502 td->td_altkstack_pages = 0; 503 } 504 505 /* 506 * Implement fork's actions on an address space. 507 * Here we arrange for the address space to be copied or referenced, 508 * allocate a user struct (pcb and kernel stack), then call the 509 * machine-dependent layer to fill those in and make the new process 510 * ready to run. The new process is set up so that it returns directly 511 * to user mode to avoid stack copying and relocation problems. 512 */ 513 int 514 vm_forkproc(td, p2, td2, vm2, flags) 515 struct thread *td; 516 struct proc *p2; 517 struct thread *td2; 518 struct vmspace *vm2; 519 int flags; 520 { 521 struct proc *p1 = td->td_proc; 522 int error; 523 524 if ((flags & RFPROC) == 0) { 525 /* 526 * Divorce the memory, if it is shared, essentially 527 * this changes shared memory amongst threads, into 528 * COW locally. 529 */ 530 if ((flags & RFMEM) == 0) { 531 if (p1->p_vmspace->vm_refcnt > 1) { 532 error = vmspace_unshare(p1); 533 if (error) 534 return (error); 535 } 536 } 537 cpu_fork(td, p2, td2, flags); 538 return (0); 539 } 540 541 if (flags & RFMEM) { 542 p2->p_vmspace = p1->p_vmspace; 543 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 544 } 545 546 while (vm_page_count_severe()) { 547 VM_WAIT; 548 } 549 550 if ((flags & RFMEM) == 0) { 551 p2->p_vmspace = vm2; 552 if (p1->p_vmspace->vm_shm) 553 shmfork(p1, p2); 554 } 555 556 /* 557 * cpu_fork will copy and update the pcb, set up the kernel stack, 558 * and make the child ready to run. 559 */ 560 cpu_fork(td, p2, td2, flags); 561 return (0); 562 } 563 564 /* 565 * Called after process has been wait(2)'ed apon and is being reaped. 566 * The idea is to reclaim resources that we could not reclaim while 567 * the process was still executing. 568 */ 569 void 570 vm_waitproc(p) 571 struct proc *p; 572 { 573 574 vmspace_exitfree(p); /* and clean-out the vmspace */ 575 } 576 577 /* 578 * Set default limits for VM system. 579 * Called for proc 0, and then inherited by all others. 580 * 581 * XXX should probably act directly on proc0. 582 */ 583 static void 584 vm_init_limits(udata) 585 void *udata; 586 { 587 struct proc *p = udata; 588 struct plimit *limp; 589 int rss_limit; 590 591 /* 592 * Set up the initial limits on process VM. Set the maximum resident 593 * set size to be half of (reasonably) available memory. Since this 594 * is a soft limit, it comes into effect only when the system is out 595 * of memory - half of main memory helps to favor smaller processes, 596 * and reduces thrashing of the object cache. 597 */ 598 limp = p->p_limit; 599 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 600 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 601 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 602 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 603 /* limit the limit to no less than 2MB */ 604 rss_limit = max(cnt.v_free_count, 512); 605 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 606 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 607 } 608 609 void 610 faultin(p) 611 struct proc *p; 612 { 613 #ifdef NO_SWAPPING 614 615 PROC_LOCK_ASSERT(p, MA_OWNED); 616 if ((p->p_flag & P_INMEM) == 0) 617 panic("faultin: proc swapped out with NO_SWAPPING!"); 618 #else /* !NO_SWAPPING */ 619 struct thread *td; 620 621 PROC_LOCK_ASSERT(p, MA_OWNED); 622 /* 623 * If another process is swapping in this process, 624 * just wait until it finishes. 625 */ 626 if (p->p_flag & P_SWAPPINGIN) { 627 while (p->p_flag & P_SWAPPINGIN) 628 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 629 return; 630 } 631 if ((p->p_flag & P_INMEM) == 0) { 632 /* 633 * Don't let another thread swap process p out while we are 634 * busy swapping it in. 635 */ 636 ++p->p_lock; 637 p->p_flag |= P_SWAPPINGIN; 638 PROC_UNLOCK(p); 639 640 /* 641 * We hold no lock here because the list of threads 642 * can not change while all threads in the process are 643 * swapped out. 644 */ 645 FOREACH_THREAD_IN_PROC(p, td) 646 vm_thread_swapin(td); 647 PROC_LOCK(p); 648 PROC_SLOCK(p); 649 swapclear(p); 650 p->p_swtick = ticks; 651 PROC_SUNLOCK(p); 652 653 wakeup(&p->p_flag); 654 655 /* Allow other threads to swap p out now. */ 656 --p->p_lock; 657 } 658 #endif /* NO_SWAPPING */ 659 } 660 661 /* 662 * This swapin algorithm attempts to swap-in processes only if there 663 * is enough space for them. Of course, if a process waits for a long 664 * time, it will be swapped in anyway. 665 * 666 * XXXKSE - process with the thread with highest priority counts.. 667 * 668 * Giant is held on entry. 669 */ 670 /* ARGSUSED*/ 671 static void 672 scheduler(dummy) 673 void *dummy; 674 { 675 struct proc *p; 676 struct thread *td; 677 struct proc *pp; 678 int slptime; 679 int swtime; 680 int ppri; 681 int pri; 682 683 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 684 mtx_unlock(&Giant); 685 686 loop: 687 if (vm_page_count_min()) { 688 VM_WAIT; 689 thread_lock(&thread0); 690 proc0_rescan = 0; 691 thread_unlock(&thread0); 692 goto loop; 693 } 694 695 pp = NULL; 696 ppri = INT_MIN; 697 sx_slock(&allproc_lock); 698 FOREACH_PROC_IN_SYSTEM(p) { 699 PROC_LOCK(p); 700 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 701 PROC_UNLOCK(p); 702 continue; 703 } 704 swtime = (ticks - p->p_swtick) / hz; 705 PROC_SLOCK(p); 706 FOREACH_THREAD_IN_PROC(p, td) { 707 /* 708 * An otherwise runnable thread of a process 709 * swapped out has only the TDI_SWAPPED bit set. 710 * 711 */ 712 thread_lock(td); 713 if (td->td_inhibitors == TDI_SWAPPED) { 714 slptime = (ticks - td->td_slptick) / hz; 715 pri = swtime + slptime; 716 if ((td->td_flags & TDF_SWAPINREQ) == 0) 717 pri -= p->p_nice * 8; 718 /* 719 * if this thread is higher priority 720 * and there is enough space, then select 721 * this process instead of the previous 722 * selection. 723 */ 724 if (pri > ppri) { 725 pp = p; 726 ppri = pri; 727 } 728 } 729 thread_unlock(td); 730 } 731 PROC_SUNLOCK(p); 732 PROC_UNLOCK(p); 733 } 734 sx_sunlock(&allproc_lock); 735 736 /* 737 * Nothing to do, back to sleep. 738 */ 739 if ((p = pp) == NULL) { 740 thread_lock(&thread0); 741 if (!proc0_rescan) { 742 TD_SET_IWAIT(&thread0); 743 mi_switch(SW_VOL, NULL); 744 } 745 proc0_rescan = 0; 746 thread_unlock(&thread0); 747 goto loop; 748 } 749 PROC_LOCK(p); 750 751 /* 752 * Another process may be bringing or may have already 753 * brought this process in while we traverse all threads. 754 * Or, this process may even be being swapped out again. 755 */ 756 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 757 PROC_UNLOCK(p); 758 thread_lock(&thread0); 759 proc0_rescan = 0; 760 thread_unlock(&thread0); 761 goto loop; 762 } 763 764 /* 765 * We would like to bring someone in. (only if there is space). 766 * [What checks the space? ] 767 */ 768 faultin(p); 769 PROC_UNLOCK(p); 770 thread_lock(&thread0); 771 proc0_rescan = 0; 772 thread_unlock(&thread0); 773 goto loop; 774 } 775 776 void kick_proc0(void) 777 { 778 struct thread *td = &thread0; 779 780 /* XXX This will probably cause a LOR in some cases */ 781 thread_lock(td); 782 if (TD_AWAITING_INTR(td)) { 783 CTR2(KTR_INTR, "%s: sched_add %d", __func__, 0); 784 TD_CLR_IWAIT(td); 785 sched_add(td, SRQ_INTR); 786 } else { 787 proc0_rescan = 1; 788 CTR2(KTR_INTR, "%s: state %d", 789 __func__, td->td_state); 790 } 791 thread_unlock(td); 792 793 } 794 795 796 #ifndef NO_SWAPPING 797 798 /* 799 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 800 */ 801 static int swap_idle_threshold1 = 2; 802 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 803 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 804 805 /* 806 * Swap_idle_threshold2 is the time that a process can be idle before 807 * it will be swapped out, if idle swapping is enabled. 808 */ 809 static int swap_idle_threshold2 = 10; 810 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 811 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 812 813 /* 814 * Swapout is driven by the pageout daemon. Very simple, we find eligible 815 * procs and swap out their stacks. We try to always "swap" at least one 816 * process in case we need the room for a swapin. 817 * If any procs have been sleeping/stopped for at least maxslp seconds, 818 * they are swapped. Else, we swap the longest-sleeping or stopped process, 819 * if any, otherwise the longest-resident process. 820 */ 821 void 822 swapout_procs(action) 823 int action; 824 { 825 struct proc *p; 826 struct thread *td; 827 int didswap = 0; 828 829 retry: 830 sx_slock(&allproc_lock); 831 FOREACH_PROC_IN_SYSTEM(p) { 832 struct vmspace *vm; 833 int minslptime = 100000; 834 int slptime; 835 836 /* 837 * Watch out for a process in 838 * creation. It may have no 839 * address space or lock yet. 840 */ 841 if (p->p_state == PRS_NEW) 842 continue; 843 /* 844 * An aio daemon switches its 845 * address space while running. 846 * Perform a quick check whether 847 * a process has P_SYSTEM. 848 */ 849 if ((p->p_flag & P_SYSTEM) != 0) 850 continue; 851 /* 852 * Do not swapout a process that 853 * is waiting for VM data 854 * structures as there is a possible 855 * deadlock. Test this first as 856 * this may block. 857 * 858 * Lock the map until swapout 859 * finishes, or a thread of this 860 * process may attempt to alter 861 * the map. 862 */ 863 vm = vmspace_acquire_ref(p); 864 if (vm == NULL) 865 continue; 866 if (!vm_map_trylock(&vm->vm_map)) 867 goto nextproc1; 868 869 PROC_LOCK(p); 870 if (p->p_lock != 0 || 871 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 872 ) != 0) { 873 goto nextproc2; 874 } 875 /* 876 * only aiod changes vmspace, however it will be 877 * skipped because of the if statement above checking 878 * for P_SYSTEM 879 */ 880 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 881 goto nextproc2; 882 883 switch (p->p_state) { 884 default: 885 /* Don't swap out processes in any sort 886 * of 'special' state. */ 887 break; 888 889 case PRS_NORMAL: 890 PROC_SLOCK(p); 891 /* 892 * do not swapout a realtime process 893 * Check all the thread groups.. 894 */ 895 FOREACH_THREAD_IN_PROC(p, td) { 896 thread_lock(td); 897 if (PRI_IS_REALTIME(td->td_pri_class)) { 898 thread_unlock(td); 899 goto nextproc; 900 } 901 slptime = (ticks - td->td_slptick) / hz; 902 /* 903 * Guarantee swap_idle_threshold1 904 * time in memory. 905 */ 906 if (slptime < swap_idle_threshold1) { 907 thread_unlock(td); 908 goto nextproc; 909 } 910 911 /* 912 * Do not swapout a process if it is 913 * waiting on a critical event of some 914 * kind or there is a thread whose 915 * pageable memory may be accessed. 916 * 917 * This could be refined to support 918 * swapping out a thread. 919 */ 920 if ((td->td_priority) < PSOCK || 921 !thread_safetoswapout(td)) { 922 thread_unlock(td); 923 goto nextproc; 924 } 925 /* 926 * If the system is under memory stress, 927 * or if we are swapping 928 * idle processes >= swap_idle_threshold2, 929 * then swap the process out. 930 */ 931 if (((action & VM_SWAP_NORMAL) == 0) && 932 (((action & VM_SWAP_IDLE) == 0) || 933 (slptime < swap_idle_threshold2))) { 934 thread_unlock(td); 935 goto nextproc; 936 } 937 938 if (minslptime > slptime) 939 minslptime = slptime; 940 thread_unlock(td); 941 } 942 943 /* 944 * If the pageout daemon didn't free enough pages, 945 * or if this process is idle and the system is 946 * configured to swap proactively, swap it out. 947 */ 948 if ((action & VM_SWAP_NORMAL) || 949 ((action & VM_SWAP_IDLE) && 950 (minslptime > swap_idle_threshold2))) { 951 if (swapout(p) == 0) 952 didswap++; 953 PROC_SUNLOCK(p); 954 PROC_UNLOCK(p); 955 vm_map_unlock(&vm->vm_map); 956 vmspace_free(vm); 957 sx_sunlock(&allproc_lock); 958 goto retry; 959 } 960 nextproc: 961 PROC_SUNLOCK(p); 962 } 963 nextproc2: 964 PROC_UNLOCK(p); 965 vm_map_unlock(&vm->vm_map); 966 nextproc1: 967 vmspace_free(vm); 968 continue; 969 } 970 sx_sunlock(&allproc_lock); 971 /* 972 * If we swapped something out, and another process needed memory, 973 * then wakeup the sched process. 974 */ 975 if (didswap) 976 wakeup(&proc0); 977 } 978 979 static void 980 swapclear(p) 981 struct proc *p; 982 { 983 struct thread *td; 984 985 PROC_LOCK_ASSERT(p, MA_OWNED); 986 PROC_SLOCK_ASSERT(p, MA_OWNED); 987 988 FOREACH_THREAD_IN_PROC(p, td) { 989 thread_lock(td); 990 td->td_flags |= TDF_INMEM; 991 td->td_flags &= ~TDF_SWAPINREQ; 992 TD_CLR_SWAPPED(td); 993 if (TD_CAN_RUN(td)) 994 setrunnable(td); 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 PROC_SLOCK_ASSERT(p, MA_OWNED | MA_NOTRECURSED); 1009 #if defined(SWAP_DEBUG) 1010 printf("swapping out %d\n", p->p_pid); 1011 #endif 1012 1013 /* 1014 * The states of this process and its threads may have changed 1015 * by now. Assuming that there is only one pageout daemon thread, 1016 * this process should still be in memory. 1017 */ 1018 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1019 ("swapout: lost a swapout race?")); 1020 1021 /* 1022 * remember the process resident count 1023 */ 1024 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1025 /* 1026 * Check and mark all threads before we proceed. 1027 */ 1028 p->p_flag &= ~P_INMEM; 1029 p->p_flag |= P_SWAPPINGOUT; 1030 FOREACH_THREAD_IN_PROC(p, td) { 1031 thread_lock(td); 1032 if (!thread_safetoswapout(td)) { 1033 thread_unlock(td); 1034 swapclear(p); 1035 return (EBUSY); 1036 } 1037 td->td_flags &= ~TDF_INMEM; 1038 TD_SET_SWAPPED(td); 1039 thread_unlock(td); 1040 } 1041 td = FIRST_THREAD_IN_PROC(p); 1042 ++td->td_ru.ru_nswap; 1043 PROC_SUNLOCK(p); 1044 PROC_UNLOCK(p); 1045 1046 /* 1047 * This list is stable because all threads are now prevented from 1048 * running. The list is only modified in the context of a running 1049 * thread in this process. 1050 */ 1051 FOREACH_THREAD_IN_PROC(p, td) 1052 vm_thread_swapout(td); 1053 1054 PROC_LOCK(p); 1055 p->p_flag &= ~P_SWAPPINGOUT; 1056 PROC_SLOCK(p); 1057 p->p_swtick = ticks; 1058 return (0); 1059 } 1060 #endif /* !NO_SWAPPING */
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