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: stable/9/sys/vm/vm_glue.c 254692 2013-08-23 13:20:11Z avg $");
61
62 #include "opt_vm.h"
63 #include "opt_kstack_pages.h"
64 #include "opt_kstack_max_pages.h"
65
66 #include <sys/param.h>
67 #include <sys/systm.h>
68 #include <sys/limits.h>
69 #include <sys/lock.h>
70 #include <sys/mutex.h>
71 #include <sys/proc.h>
72 #include <sys/racct.h>
73 #include <sys/resourcevar.h>
74 #include <sys/sched.h>
75 #include <sys/sf_buf.h>
76 #include <sys/shm.h>
77 #include <sys/vmmeter.h>
78 #include <sys/sx.h>
79 #include <sys/sysctl.h>
80 #include <sys/_kstack_cache.h>
81 #include <sys/eventhandler.h>
82 #include <sys/kernel.h>
83 #include <sys/ktr.h>
84 #include <sys/unistd.h>
85
86 #include <vm/vm.h>
87 #include <vm/vm_param.h>
88 #include <vm/pmap.h>
89 #include <vm/vm_map.h>
90 #include <vm/vm_page.h>
91 #include <vm/vm_pageout.h>
92 #include <vm/vm_object.h>
93 #include <vm/vm_kern.h>
94 #include <vm/vm_extern.h>
95 #include <vm/vm_pager.h>
96 #include <vm/swap_pager.h>
97
98 #ifndef NO_SWAPPING
99 static int swapout(struct proc *);
100 static void swapclear(struct proc *);
101 static void vm_thread_swapin(struct thread *td);
102 static void vm_thread_swapout(struct thread *td);
103 #endif
104
105 /*
106 * MPSAFE
107 *
108 * WARNING! This code calls vm_map_check_protection() which only checks
109 * the associated vm_map_entry range. It does not determine whether the
110 * contents of the memory is actually readable or writable. In most cases
111 * just checking the vm_map_entry is sufficient within the kernel's address
112 * space.
113 */
114 int
kernacc(addr,len,rw)115 kernacc(addr, len, rw)
116 void *addr;
117 int len, rw;
118 {
119 boolean_t rv;
120 vm_offset_t saddr, eaddr;
121 vm_prot_t prot;
122
123 KASSERT((rw & ~VM_PROT_ALL) == 0,
124 ("illegal ``rw'' argument to kernacc (%x)\n", rw));
125
126 if ((vm_offset_t)addr + len > kernel_map->max_offset ||
127 (vm_offset_t)addr + len < (vm_offset_t)addr)
128 return (FALSE);
129
130 prot = rw;
131 saddr = trunc_page((vm_offset_t)addr);
132 eaddr = round_page((vm_offset_t)addr + len);
133 vm_map_lock_read(kernel_map);
134 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
135 vm_map_unlock_read(kernel_map);
136 return (rv == TRUE);
137 }
138
139 /*
140 * MPSAFE
141 *
142 * WARNING! This code calls vm_map_check_protection() which only checks
143 * the associated vm_map_entry range. It does not determine whether the
144 * contents of the memory is actually readable or writable. vmapbuf(),
145 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
146 * used in conjuction with this call.
147 */
148 int
useracc(addr,len,rw)149 useracc(addr, len, rw)
150 void *addr;
151 int len, rw;
152 {
153 boolean_t rv;
154 vm_prot_t prot;
155 vm_map_t map;
156
157 KASSERT((rw & ~VM_PROT_ALL) == 0,
158 ("illegal ``rw'' argument to useracc (%x)\n", rw));
159 prot = rw;
160 map = &curproc->p_vmspace->vm_map;
161 if ((vm_offset_t)addr + len > vm_map_max(map) ||
162 (vm_offset_t)addr + len < (vm_offset_t)addr) {
163 return (FALSE);
164 }
165 vm_map_lock_read(map);
166 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
167 round_page((vm_offset_t)addr + len), prot);
168 vm_map_unlock_read(map);
169 return (rv == TRUE);
170 }
171
172 int
vslock(void * addr,size_t len)173 vslock(void *addr, size_t len)
174 {
175 vm_offset_t end, last, start;
176 vm_size_t npages;
177 int error;
178
179 last = (vm_offset_t)addr + len;
180 start = trunc_page((vm_offset_t)addr);
181 end = round_page(last);
182 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
183 return (EINVAL);
184 npages = atop(end - start);
185 if (npages > vm_page_max_wired)
186 return (ENOMEM);
187 #if 0
188 /*
189 * XXX - not yet
190 *
191 * The limit for transient usage of wired pages should be
192 * larger than for "permanent" wired pages (mlock()).
193 *
194 * Also, the sysctl code, which is the only present user
195 * of vslock(), does a hard loop on EAGAIN.
196 */
197 if (npages + cnt.v_wire_count > vm_page_max_wired)
198 return (EAGAIN);
199 #endif
200 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
201 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
202 /*
203 * Return EFAULT on error to match copy{in,out}() behaviour
204 * rather than returning ENOMEM like mlock() would.
205 */
206 return (error == KERN_SUCCESS ? 0 : EFAULT);
207 }
208
209 void
vsunlock(void * addr,size_t len)210 vsunlock(void *addr, size_t len)
211 {
212
213 /* Rely on the parameter sanity checks performed by vslock(). */
214 (void)vm_map_unwire(&curproc->p_vmspace->vm_map,
215 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
216 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
217 }
218
219 /*
220 * Pin the page contained within the given object at the given offset. If the
221 * page is not resident, allocate and load it using the given object's pager.
222 * Return the pinned page if successful; otherwise, return NULL.
223 */
224 static vm_page_t
vm_imgact_hold_page(vm_object_t object,vm_ooffset_t offset)225 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
226 {
227 vm_page_t m, ma[1];
228 vm_pindex_t pindex;
229 int rv;
230
231 VM_OBJECT_LOCK(object);
232 pindex = OFF_TO_IDX(offset);
233 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
234 if (m->valid != VM_PAGE_BITS_ALL) {
235 ma[0] = m;
236 rv = vm_pager_get_pages(object, ma, 1, 0);
237 m = vm_page_lookup(object, pindex);
238 if (m == NULL)
239 goto out;
240 if (rv != VM_PAGER_OK) {
241 vm_page_lock(m);
242 vm_page_free(m);
243 vm_page_unlock(m);
244 m = NULL;
245 goto out;
246 }
247 }
248 vm_page_lock(m);
249 vm_page_hold(m);
250 vm_page_unlock(m);
251 vm_page_wakeup(m);
252 out:
253 VM_OBJECT_UNLOCK(object);
254 return (m);
255 }
256
257 /*
258 * Return a CPU private mapping to the page at the given offset within the
259 * given object. The page is pinned before it is mapped.
260 */
261 struct sf_buf *
vm_imgact_map_page(vm_object_t object,vm_ooffset_t offset)262 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
263 {
264 vm_page_t m;
265
266 m = vm_imgact_hold_page(object, offset);
267 if (m == NULL)
268 return (NULL);
269 sched_pin();
270 return (sf_buf_alloc(m, SFB_CPUPRIVATE));
271 }
272
273 /*
274 * Destroy the given CPU private mapping and unpin the page that it mapped.
275 */
276 void
vm_imgact_unmap_page(struct sf_buf * sf)277 vm_imgact_unmap_page(struct sf_buf *sf)
278 {
279 vm_page_t m;
280
281 m = sf_buf_page(sf);
282 sf_buf_free(sf);
283 sched_unpin();
284 vm_page_lock(m);
285 vm_page_unhold(m);
286 vm_page_unlock(m);
287 }
288
289 void
vm_sync_icache(vm_map_t map,vm_offset_t va,vm_offset_t sz)290 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
291 {
292
293 pmap_sync_icache(map->pmap, va, sz);
294 }
295
296 struct kstack_cache_entry *kstack_cache;
297 static int kstack_cache_size = 128;
298 static int kstacks;
299 static struct mtx kstack_cache_mtx;
300 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0,
301 "");
302 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
303 "");
304
305 #ifndef KSTACK_MAX_PAGES
306 #define KSTACK_MAX_PAGES 32
307 #endif
308
309 /*
310 * Create the kernel stack (including pcb for i386) for a new thread.
311 * This routine directly affects the fork perf for a process and
312 * create performance for a thread.
313 */
314 int
vm_thread_new(struct thread * td,int pages)315 vm_thread_new(struct thread *td, int pages)
316 {
317 vm_object_t ksobj;
318 vm_offset_t ks;
319 vm_page_t m, ma[KSTACK_MAX_PAGES];
320 struct kstack_cache_entry *ks_ce;
321 int i;
322
323 /* Bounds check */
324 if (pages <= 1)
325 pages = KSTACK_PAGES;
326 else if (pages > KSTACK_MAX_PAGES)
327 pages = KSTACK_MAX_PAGES;
328
329 if (pages == KSTACK_PAGES) {
330 mtx_lock(&kstack_cache_mtx);
331 if (kstack_cache != NULL) {
332 ks_ce = kstack_cache;
333 kstack_cache = ks_ce->next_ks_entry;
334 mtx_unlock(&kstack_cache_mtx);
335
336 td->td_kstack_obj = ks_ce->ksobj;
337 td->td_kstack = (vm_offset_t)ks_ce;
338 td->td_kstack_pages = KSTACK_PAGES;
339 return (1);
340 }
341 mtx_unlock(&kstack_cache_mtx);
342 }
343
344 /*
345 * Allocate an object for the kstack.
346 */
347 ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
348
349 /*
350 * Get a kernel virtual address for this thread's kstack.
351 */
352 #if defined(__mips__)
353 /*
354 * We need to align the kstack's mapped address to fit within
355 * a single TLB entry.
356 */
357 ks = kmem_alloc_nofault_space(kernel_map,
358 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE, VMFS_TLB_ALIGNED_SPACE);
359 #else
360 ks = kmem_alloc_nofault(kernel_map,
361 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
362 #endif
363 if (ks == 0) {
364 printf("vm_thread_new: kstack allocation failed\n");
365 vm_object_deallocate(ksobj);
366 return (0);
367 }
368
369 atomic_add_int(&kstacks, 1);
370 if (KSTACK_GUARD_PAGES != 0) {
371 pmap_qremove(ks, KSTACK_GUARD_PAGES);
372 ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
373 }
374 td->td_kstack_obj = ksobj;
375 td->td_kstack = ks;
376 /*
377 * Knowing the number of pages allocated is useful when you
378 * want to deallocate them.
379 */
380 td->td_kstack_pages = pages;
381 /*
382 * For the length of the stack, link in a real page of ram for each
383 * page of stack.
384 */
385 VM_OBJECT_LOCK(ksobj);
386 for (i = 0; i < pages; i++) {
387 /*
388 * Get a kernel stack page.
389 */
390 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY |
391 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED);
392 ma[i] = m;
393 m->valid = VM_PAGE_BITS_ALL;
394 }
395 VM_OBJECT_UNLOCK(ksobj);
396 pmap_qenter(ks, ma, pages);
397 return (1);
398 }
399
400 static void
vm_thread_stack_dispose(vm_object_t ksobj,vm_offset_t ks,int pages)401 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
402 {
403 vm_page_t m;
404 int i;
405
406 atomic_add_int(&kstacks, -1);
407 pmap_qremove(ks, pages);
408 VM_OBJECT_LOCK(ksobj);
409 for (i = 0; i < pages; i++) {
410 m = vm_page_lookup(ksobj, i);
411 if (m == NULL)
412 panic("vm_thread_dispose: kstack already missing?");
413 vm_page_lock(m);
414 vm_page_unwire(m, 0);
415 vm_page_free(m);
416 vm_page_unlock(m);
417 }
418 VM_OBJECT_UNLOCK(ksobj);
419 vm_object_deallocate(ksobj);
420 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
421 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
422 }
423
424 /*
425 * Dispose of a thread's kernel stack.
426 */
427 void
vm_thread_dispose(struct thread * td)428 vm_thread_dispose(struct thread *td)
429 {
430 vm_object_t ksobj;
431 vm_offset_t ks;
432 struct kstack_cache_entry *ks_ce;
433 int pages;
434
435 pages = td->td_kstack_pages;
436 ksobj = td->td_kstack_obj;
437 ks = td->td_kstack;
438 td->td_kstack = 0;
439 td->td_kstack_pages = 0;
440 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) {
441 ks_ce = (struct kstack_cache_entry *)ks;
442 ks_ce->ksobj = ksobj;
443 mtx_lock(&kstack_cache_mtx);
444 ks_ce->next_ks_entry = kstack_cache;
445 kstack_cache = ks_ce;
446 mtx_unlock(&kstack_cache_mtx);
447 return;
448 }
449 vm_thread_stack_dispose(ksobj, ks, pages);
450 }
451
452 static void
vm_thread_stack_lowmem(void * nulll)453 vm_thread_stack_lowmem(void *nulll)
454 {
455 struct kstack_cache_entry *ks_ce, *ks_ce1;
456
457 mtx_lock(&kstack_cache_mtx);
458 ks_ce = kstack_cache;
459 kstack_cache = NULL;
460 mtx_unlock(&kstack_cache_mtx);
461
462 while (ks_ce != NULL) {
463 ks_ce1 = ks_ce;
464 ks_ce = ks_ce->next_ks_entry;
465
466 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1,
467 KSTACK_PAGES);
468 }
469 }
470
471 static void
kstack_cache_init(void * nulll)472 kstack_cache_init(void *nulll)
473 {
474
475 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL,
476 EVENTHANDLER_PRI_ANY);
477 }
478
479 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);
480 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
481
482 #ifndef NO_SWAPPING
483 /*
484 * Allow a thread's kernel stack to be paged out.
485 */
486 static void
vm_thread_swapout(struct thread * td)487 vm_thread_swapout(struct thread *td)
488 {
489 vm_object_t ksobj;
490 vm_page_t m;
491 int i, pages;
492
493 cpu_thread_swapout(td);
494 pages = td->td_kstack_pages;
495 ksobj = td->td_kstack_obj;
496 pmap_qremove(td->td_kstack, pages);
497 VM_OBJECT_LOCK(ksobj);
498 for (i = 0; i < pages; i++) {
499 m = vm_page_lookup(ksobj, i);
500 if (m == NULL)
501 panic("vm_thread_swapout: kstack already missing?");
502 vm_page_dirty(m);
503 vm_page_lock(m);
504 vm_page_unwire(m, 0);
505 vm_page_unlock(m);
506 }
507 VM_OBJECT_UNLOCK(ksobj);
508 }
509
510 /*
511 * Bring the kernel stack for a specified thread back in.
512 */
513 static void
vm_thread_swapin(struct thread * td)514 vm_thread_swapin(struct thread *td)
515 {
516 vm_object_t ksobj;
517 vm_page_t ma[KSTACK_MAX_PAGES];
518 int i, j, k, pages, rv;
519
520 pages = td->td_kstack_pages;
521 ksobj = td->td_kstack_obj;
522 VM_OBJECT_LOCK(ksobj);
523 for (i = 0; i < pages; i++)
524 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY |
525 VM_ALLOC_WIRED);
526 for (i = 0; i < pages; i++) {
527 if (ma[i]->valid != VM_PAGE_BITS_ALL) {
528 KASSERT(ma[i]->oflags & VPO_BUSY,
529 ("lost busy 1"));
530 vm_object_pip_add(ksobj, 1);
531 for (j = i + 1; j < pages; j++) {
532 KASSERT(ma[j]->valid == VM_PAGE_BITS_ALL ||
533 (ma[j]->oflags & VPO_BUSY),
534 ("lost busy 2"));
535 if (ma[j]->valid == VM_PAGE_BITS_ALL)
536 break;
537 }
538 rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0);
539 if (rv != VM_PAGER_OK)
540 panic("vm_thread_swapin: cannot get kstack for proc: %d",
541 td->td_proc->p_pid);
542 vm_object_pip_wakeup(ksobj);
543 for (k = i; k < j; k++)
544 ma[k] = vm_page_lookup(ksobj, k);
545 vm_page_wakeup(ma[i]);
546 } else if (ma[i]->oflags & VPO_BUSY)
547 vm_page_wakeup(ma[i]);
548 }
549 VM_OBJECT_UNLOCK(ksobj);
550 pmap_qenter(td->td_kstack, ma, pages);
551 cpu_thread_swapin(td);
552 }
553 #endif /* !NO_SWAPPING */
554
555 /*
556 * Implement fork's actions on an address space.
557 * Here we arrange for the address space to be copied or referenced,
558 * allocate a user struct (pcb and kernel stack), then call the
559 * machine-dependent layer to fill those in and make the new process
560 * ready to run. The new process is set up so that it returns directly
561 * to user mode to avoid stack copying and relocation problems.
562 */
563 int
vm_forkproc(td,p2,td2,vm2,flags)564 vm_forkproc(td, p2, td2, vm2, flags)
565 struct thread *td;
566 struct proc *p2;
567 struct thread *td2;
568 struct vmspace *vm2;
569 int flags;
570 {
571 struct proc *p1 = td->td_proc;
572 int error;
573
574 if ((flags & RFPROC) == 0) {
575 /*
576 * Divorce the memory, if it is shared, essentially
577 * this changes shared memory amongst threads, into
578 * COW locally.
579 */
580 if ((flags & RFMEM) == 0) {
581 if (p1->p_vmspace->vm_refcnt > 1) {
582 error = vmspace_unshare(p1);
583 if (error)
584 return (error);
585 }
586 }
587 cpu_fork(td, p2, td2, flags);
588 return (0);
589 }
590
591 if (flags & RFMEM) {
592 p2->p_vmspace = p1->p_vmspace;
593 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1);
594 }
595
596 while (vm_page_count_severe()) {
597 VM_WAIT;
598 }
599
600 if ((flags & RFMEM) == 0) {
601 p2->p_vmspace = vm2;
602 if (p1->p_vmspace->vm_shm)
603 shmfork(p1, p2);
604 }
605
606 /*
607 * cpu_fork will copy and update the pcb, set up the kernel stack,
608 * and make the child ready to run.
609 */
610 cpu_fork(td, p2, td2, flags);
611 return (0);
612 }
613
614 /*
615 * Called after process has been wait(2)'ed apon and is being reaped.
616 * The idea is to reclaim resources that we could not reclaim while
617 * the process was still executing.
618 */
619 void
vm_waitproc(p)620 vm_waitproc(p)
621 struct proc *p;
622 {
623
624 vmspace_exitfree(p); /* and clean-out the vmspace */
625 }
626
627 void
faultin(p)628 faultin(p)
629 struct proc *p;
630 {
631 #ifdef NO_SWAPPING
632
633 PROC_LOCK_ASSERT(p, MA_OWNED);
634 if ((p->p_flag & P_INMEM) == 0)
635 panic("faultin: proc swapped out with NO_SWAPPING!");
636 #else /* !NO_SWAPPING */
637 struct thread *td;
638
639 PROC_LOCK_ASSERT(p, MA_OWNED);
640 /*
641 * If another process is swapping in this process,
642 * just wait until it finishes.
643 */
644 if (p->p_flag & P_SWAPPINGIN) {
645 while (p->p_flag & P_SWAPPINGIN)
646 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
647 return;
648 }
649 if ((p->p_flag & P_INMEM) == 0) {
650 /*
651 * Don't let another thread swap process p out while we are
652 * busy swapping it in.
653 */
654 ++p->p_lock;
655 p->p_flag |= P_SWAPPINGIN;
656 PROC_UNLOCK(p);
657
658 /*
659 * We hold no lock here because the list of threads
660 * can not change while all threads in the process are
661 * swapped out.
662 */
663 FOREACH_THREAD_IN_PROC(p, td)
664 vm_thread_swapin(td);
665 PROC_LOCK(p);
666 swapclear(p);
667 p->p_swtick = ticks;
668
669 wakeup(&p->p_flag);
670
671 /* Allow other threads to swap p out now. */
672 --p->p_lock;
673 }
674 #endif /* NO_SWAPPING */
675 }
676
677 /*
678 * This swapin algorithm attempts to swap-in processes only if there
679 * is enough space for them. Of course, if a process waits for a long
680 * time, it will be swapped in anyway.
681 *
682 * Giant is held on entry.
683 */
684 void
swapper(void)685 swapper(void)
686 {
687 struct proc *p;
688 struct thread *td;
689 struct proc *pp;
690 int slptime;
691 int swtime;
692 int ppri;
693 int pri;
694
695 loop:
696 if (vm_page_count_min()) {
697 VM_WAIT;
698 goto loop;
699 }
700
701 pp = NULL;
702 ppri = INT_MIN;
703 sx_slock(&allproc_lock);
704 FOREACH_PROC_IN_SYSTEM(p) {
705 PROC_LOCK(p);
706 if (p->p_state == PRS_NEW ||
707 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) {
708 PROC_UNLOCK(p);
709 continue;
710 }
711 swtime = (ticks - p->p_swtick) / hz;
712 FOREACH_THREAD_IN_PROC(p, td) {
713 /*
714 * An otherwise runnable thread of a process
715 * swapped out has only the TDI_SWAPPED bit set.
716 *
717 */
718 thread_lock(td);
719 if (td->td_inhibitors == TDI_SWAPPED) {
720 slptime = (ticks - td->td_slptick) / hz;
721 pri = swtime + slptime;
722 if ((td->td_flags & TDF_SWAPINREQ) == 0)
723 pri -= p->p_nice * 8;
724 /*
725 * if this thread is higher priority
726 * and there is enough space, then select
727 * this process instead of the previous
728 * selection.
729 */
730 if (pri > ppri) {
731 pp = p;
732 ppri = pri;
733 }
734 }
735 thread_unlock(td);
736 }
737 PROC_UNLOCK(p);
738 }
739 sx_sunlock(&allproc_lock);
740
741 /*
742 * Nothing to do, back to sleep.
743 */
744 if ((p = pp) == NULL) {
745 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2);
746 goto loop;
747 }
748 PROC_LOCK(p);
749
750 /*
751 * Another process may be bringing or may have already
752 * brought this process in while we traverse all threads.
753 * Or, this process may even be being swapped out again.
754 */
755 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) {
756 PROC_UNLOCK(p);
757 goto loop;
758 }
759
760 /*
761 * We would like to bring someone in. (only if there is space).
762 * [What checks the space? ]
763 */
764 faultin(p);
765 PROC_UNLOCK(p);
766 goto loop;
767 }
768
769 void
kick_proc0(void)770 kick_proc0(void)
771 {
772
773 wakeup(&proc0);
774 }
775
776 #ifndef NO_SWAPPING
777
778 /*
779 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
780 */
781 static int swap_idle_threshold1 = 2;
782 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
783 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process");
784
785 /*
786 * Swap_idle_threshold2 is the time that a process can be idle before
787 * it will be swapped out, if idle swapping is enabled.
788 */
789 static int swap_idle_threshold2 = 10;
790 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
791 &swap_idle_threshold2, 0, "Time before a process will be swapped out");
792
793 /*
794 * First, if any processes have been sleeping or stopped for at least
795 * "swap_idle_threshold1" seconds, they are swapped out. If, however,
796 * no such processes exist, then the longest-sleeping or stopped
797 * process is swapped out. Finally, and only as a last resort, if
798 * there are no sleeping or stopped processes, the longest-resident
799 * process is swapped out.
800 */
801 void
swapout_procs(action)802 swapout_procs(action)
803 int action;
804 {
805 struct proc *p;
806 struct thread *td;
807 int didswap = 0;
808
809 retry:
810 sx_slock(&allproc_lock);
811 FOREACH_PROC_IN_SYSTEM(p) {
812 struct vmspace *vm;
813 int minslptime = 100000;
814 int slptime;
815
816 /*
817 * Watch out for a process in
818 * creation. It may have no
819 * address space or lock yet.
820 */
821 if (p->p_state == PRS_NEW)
822 continue;
823 /*
824 * An aio daemon switches its
825 * address space while running.
826 * Perform a quick check whether
827 * a process has P_SYSTEM.
828 */
829 if ((p->p_flag & P_SYSTEM) != 0)
830 continue;
831 /*
832 * Do not swapout a process that
833 * is waiting for VM data
834 * structures as there is a possible
835 * deadlock. Test this first as
836 * this may block.
837 *
838 * Lock the map until swapout
839 * finishes, or a thread of this
840 * process may attempt to alter
841 * the map.
842 */
843 vm = vmspace_acquire_ref(p);
844 if (vm == NULL)
845 continue;
846 if (!vm_map_trylock(&vm->vm_map))
847 goto nextproc1;
848
849 PROC_LOCK(p);
850 if (p->p_lock != 0 ||
851 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT)
852 ) != 0) {
853 goto nextproc;
854 }
855 /*
856 * only aiod changes vmspace, however it will be
857 * skipped because of the if statement above checking
858 * for P_SYSTEM
859 */
860 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM)
861 goto nextproc;
862
863 switch (p->p_state) {
864 default:
865 /* Don't swap out processes in any sort
866 * of 'special' state. */
867 break;
868
869 case PRS_NORMAL:
870 /*
871 * do not swapout a realtime process
872 * Check all the thread groups..
873 */
874 FOREACH_THREAD_IN_PROC(p, td) {
875 thread_lock(td);
876 if (PRI_IS_REALTIME(td->td_pri_class)) {
877 thread_unlock(td);
878 goto nextproc;
879 }
880 slptime = (ticks - td->td_slptick) / hz;
881 /*
882 * Guarantee swap_idle_threshold1
883 * time in memory.
884 */
885 if (slptime < swap_idle_threshold1) {
886 thread_unlock(td);
887 goto nextproc;
888 }
889
890 /*
891 * Do not swapout a process if it is
892 * waiting on a critical event of some
893 * kind or there is a thread whose
894 * pageable memory may be accessed.
895 *
896 * This could be refined to support
897 * swapping out a thread.
898 */
899 if (!thread_safetoswapout(td)) {
900 thread_unlock(td);
901 goto nextproc;
902 }
903 /*
904 * If the system is under memory stress,
905 * or if we are swapping
906 * idle processes >= swap_idle_threshold2,
907 * then swap the process out.
908 */
909 if (((action & VM_SWAP_NORMAL) == 0) &&
910 (((action & VM_SWAP_IDLE) == 0) ||
911 (slptime < swap_idle_threshold2))) {
912 thread_unlock(td);
913 goto nextproc;
914 }
915
916 if (minslptime > slptime)
917 minslptime = slptime;
918 thread_unlock(td);
919 }
920
921 /*
922 * If the pageout daemon didn't free enough pages,
923 * or if this process is idle and the system is
924 * configured to swap proactively, swap it out.
925 */
926 if ((action & VM_SWAP_NORMAL) ||
927 ((action & VM_SWAP_IDLE) &&
928 (minslptime > swap_idle_threshold2))) {
929 if (swapout(p) == 0)
930 didswap++;
931 PROC_UNLOCK(p);
932 vm_map_unlock(&vm->vm_map);
933 vmspace_free(vm);
934 sx_sunlock(&allproc_lock);
935 goto retry;
936 }
937 }
938 nextproc:
939 PROC_UNLOCK(p);
940 vm_map_unlock(&vm->vm_map);
941 nextproc1:
942 vmspace_free(vm);
943 continue;
944 }
945 sx_sunlock(&allproc_lock);
946 /*
947 * If we swapped something out, and another process needed memory,
948 * then wakeup the sched process.
949 */
950 if (didswap)
951 wakeup(&proc0);
952 }
953
954 static void
swapclear(p)955 swapclear(p)
956 struct proc *p;
957 {
958 struct thread *td;
959
960 PROC_LOCK_ASSERT(p, MA_OWNED);
961
962 FOREACH_THREAD_IN_PROC(p, td) {
963 thread_lock(td);
964 td->td_flags |= TDF_INMEM;
965 td->td_flags &= ~TDF_SWAPINREQ;
966 TD_CLR_SWAPPED(td);
967 if (TD_CAN_RUN(td))
968 if (setrunnable(td)) {
969 #ifdef INVARIANTS
970 /*
971 * XXX: We just cleared TDI_SWAPPED
972 * above and set TDF_INMEM, so this
973 * should never happen.
974 */
975 panic("not waking up swapper");
976 #endif
977 }
978 thread_unlock(td);
979 }
980 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT);
981 p->p_flag |= P_INMEM;
982 }
983
984 static int
swapout(p)985 swapout(p)
986 struct proc *p;
987 {
988 struct thread *td;
989
990 PROC_LOCK_ASSERT(p, MA_OWNED);
991 #if defined(SWAP_DEBUG)
992 printf("swapping out %d\n", p->p_pid);
993 #endif
994
995 /*
996 * The states of this process and its threads may have changed
997 * by now. Assuming that there is only one pageout daemon thread,
998 * this process should still be in memory.
999 */
1000 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM,
1001 ("swapout: lost a swapout race?"));
1002
1003 /*
1004 * remember the process resident count
1005 */
1006 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
1007 /*
1008 * Check and mark all threads before we proceed.
1009 */
1010 p->p_flag &= ~P_INMEM;
1011 p->p_flag |= P_SWAPPINGOUT;
1012 FOREACH_THREAD_IN_PROC(p, td) {
1013 thread_lock(td);
1014 if (!thread_safetoswapout(td)) {
1015 thread_unlock(td);
1016 swapclear(p);
1017 return (EBUSY);
1018 }
1019 td->td_flags &= ~TDF_INMEM;
1020 TD_SET_SWAPPED(td);
1021 thread_unlock(td);
1022 }
1023 td = FIRST_THREAD_IN_PROC(p);
1024 ++td->td_ru.ru_nswap;
1025 PROC_UNLOCK(p);
1026
1027 /*
1028 * This list is stable because all threads are now prevented from
1029 * running. The list is only modified in the context of a running
1030 * thread in this process.
1031 */
1032 FOREACH_THREAD_IN_PROC(p, td)
1033 vm_thread_swapout(td);
1034
1035 PROC_LOCK(p);
1036 p->p_flag &= ~P_SWAPPINGOUT;
1037 p->p_swtick = ticks;
1038 return (0);
1039 }
1040 #endif /* !NO_SWAPPING */
1041