FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_kern.c
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_kern.c 8.3 (Berkeley) 1/12/94
33 *
34 *
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
37 *
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
39 *
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
45 *
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
49 *
50 * Carnegie Mellon requests users of this software to return to
51 *
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
56 *
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
59 */
60
61 /*
62 * Kernel memory management.
63 */
64
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD$");
67
68 #include <sys/param.h>
69 #include <sys/systm.h>
70 #include <sys/kernel.h> /* for ticks and hz */
71 #include <sys/eventhandler.h>
72 #include <sys/lock.h>
73 #include <sys/mutex.h>
74 #include <sys/proc.h>
75 #include <sys/malloc.h>
76 #include <sys/sysctl.h>
77
78 #include <vm/vm.h>
79 #include <vm/vm_param.h>
80 #include <vm/pmap.h>
81 #include <vm/vm_map.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pageout.h>
85 #include <vm/vm_extern.h>
86 #include <vm/uma.h>
87
88 vm_map_t kernel_map;
89 vm_map_t kmem_map;
90 vm_map_t exec_map;
91 vm_map_t pipe_map;
92 vm_map_t buffer_map;
93 vm_map_t bio_transient_map;
94
95 const void *zero_region;
96 CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
97
98 /*
99 * kmem_alloc_nofault:
100 *
101 * Allocate a virtual address range with no underlying object and
102 * no initial mapping to physical memory. Any mapping from this
103 * range to physical memory must be explicitly created prior to
104 * its use, typically with pmap_qenter(). Any attempt to create
105 * a mapping on demand through vm_fault() will result in a panic.
106 */
107 vm_offset_t
108 kmem_alloc_nofault(map, size)
109 vm_map_t map;
110 vm_size_t size;
111 {
112 vm_offset_t addr;
113 int result;
114
115 size = round_page(size);
116 addr = vm_map_min(map);
117 result = vm_map_find(map, NULL, 0, &addr, size, VMFS_ANY_SPACE,
118 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
119 if (result != KERN_SUCCESS) {
120 return (0);
121 }
122 return (addr);
123 }
124
125 /*
126 * kmem_alloc_nofault_space:
127 *
128 * Allocate a virtual address range with no underlying object and
129 * no initial mapping to physical memory within the specified
130 * address space. Any mapping from this range to physical memory
131 * must be explicitly created prior to its use, typically with
132 * pmap_qenter(). Any attempt to create a mapping on demand
133 * through vm_fault() will result in a panic.
134 */
135 vm_offset_t
136 kmem_alloc_nofault_space(map, size, find_space)
137 vm_map_t map;
138 vm_size_t size;
139 int find_space;
140 {
141 vm_offset_t addr;
142 int result;
143
144 size = round_page(size);
145 addr = vm_map_min(map);
146 result = vm_map_find(map, NULL, 0, &addr, size, find_space,
147 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
148 if (result != KERN_SUCCESS) {
149 return (0);
150 }
151 return (addr);
152 }
153
154 /*
155 * Allocate wired-down memory in the kernel's address map
156 * or a submap.
157 */
158 vm_offset_t
159 kmem_alloc(map, size)
160 vm_map_t map;
161 vm_size_t size;
162 {
163 vm_offset_t addr;
164 vm_offset_t offset;
165
166 size = round_page(size);
167
168 /*
169 * Use the kernel object for wired-down kernel pages. Assume that no
170 * region of the kernel object is referenced more than once.
171 */
172
173 /*
174 * Locate sufficient space in the map. This will give us the final
175 * virtual address for the new memory, and thus will tell us the
176 * offset within the kernel map.
177 */
178 vm_map_lock(map);
179 if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
180 vm_map_unlock(map);
181 return (0);
182 }
183 offset = addr - VM_MIN_KERNEL_ADDRESS;
184 vm_object_reference(kernel_object);
185 vm_map_insert(map, kernel_object, offset, addr, addr + size,
186 VM_PROT_ALL, VM_PROT_ALL, 0);
187 vm_map_unlock(map);
188
189 /*
190 * And finally, mark the data as non-pageable.
191 */
192 (void) vm_map_wire(map, addr, addr + size,
193 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
194
195 return (addr);
196 }
197
198 /*
199 * kmem_free:
200 *
201 * Release a region of kernel virtual memory allocated
202 * with kmem_alloc, and return the physical pages
203 * associated with that region.
204 *
205 * This routine may not block on kernel maps.
206 */
207 void
208 kmem_free(map, addr, size)
209 vm_map_t map;
210 vm_offset_t addr;
211 vm_size_t size;
212 {
213
214 (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
215 }
216
217 /*
218 * kmem_suballoc:
219 *
220 * Allocates a map to manage a subrange
221 * of the kernel virtual address space.
222 *
223 * Arguments are as follows:
224 *
225 * parent Map to take range from
226 * min, max Returned endpoints of map
227 * size Size of range to find
228 * superpage_align Request that min is superpage aligned
229 */
230 vm_map_t
231 kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
232 vm_size_t size, boolean_t superpage_align)
233 {
234 int ret;
235 vm_map_t result;
236
237 size = round_page(size);
238
239 *min = vm_map_min(parent);
240 ret = vm_map_find(parent, NULL, 0, min, size, superpage_align ?
241 VMFS_SUPER_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
242 MAP_ACC_NO_CHARGE);
243 if (ret != KERN_SUCCESS)
244 panic("kmem_suballoc: bad status return of %d", ret);
245 *max = *min + size;
246 result = vm_map_create(vm_map_pmap(parent), *min, *max);
247 if (result == NULL)
248 panic("kmem_suballoc: cannot create submap");
249 if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
250 panic("kmem_suballoc: unable to change range to submap");
251 return (result);
252 }
253
254 /*
255 * kmem_malloc:
256 *
257 * Allocate wired-down memory in the kernel's address map for the higher
258 * level kernel memory allocator (kern/kern_malloc.c). We cannot use
259 * kmem_alloc() because we may need to allocate memory at interrupt
260 * level where we cannot block (canwait == FALSE).
261 *
262 * This routine has its own private kernel submap (kmem_map) and object
263 * (kmem_object). This, combined with the fact that only malloc uses
264 * this routine, ensures that we will never block in map or object waits.
265 *
266 * We don't worry about expanding the map (adding entries) since entries
267 * for wired maps are statically allocated.
268 *
269 * `map' is ONLY allowed to be kmem_map or one of the mbuf submaps to
270 * which we never free.
271 */
272 vm_offset_t
273 kmem_malloc(map, size, flags)
274 vm_map_t map;
275 vm_size_t size;
276 int flags;
277 {
278 vm_offset_t addr;
279 int i, rv;
280
281 size = round_page(size);
282 addr = vm_map_min(map);
283
284 /*
285 * Locate sufficient space in the map. This will give us the final
286 * virtual address for the new memory, and thus will tell us the
287 * offset within the kernel map.
288 */
289 vm_map_lock(map);
290 if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
291 vm_map_unlock(map);
292 if ((flags & M_NOWAIT) == 0) {
293 for (i = 0; i < 8; i++) {
294 EVENTHANDLER_INVOKE(vm_lowmem, 0);
295 uma_reclaim();
296 vm_map_lock(map);
297 if (vm_map_findspace(map, vm_map_min(map),
298 size, &addr) == 0) {
299 break;
300 }
301 vm_map_unlock(map);
302 tsleep(&i, 0, "nokva", (hz / 4) * (i + 1));
303 }
304 if (i == 8) {
305 panic("kmem_malloc(%ld): kmem_map too small: %ld total allocated",
306 (long)size, (long)map->size);
307 }
308 } else {
309 return (0);
310 }
311 }
312
313 rv = kmem_back(map, addr, size, flags);
314 vm_map_unlock(map);
315 return (rv == KERN_SUCCESS ? addr : 0);
316 }
317
318 /*
319 * kmem_back:
320 *
321 * Allocate physical pages for the specified virtual address range.
322 */
323 int
324 kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
325 {
326 vm_offset_t offset, i;
327 vm_map_entry_t entry;
328 vm_page_t m;
329 int pflags;
330 boolean_t found;
331
332 KASSERT(vm_map_locked(map), ("kmem_back: map %p is not locked", map));
333 offset = addr - VM_MIN_KERNEL_ADDRESS;
334 vm_object_reference(kmem_object);
335 vm_map_insert(map, kmem_object, offset, addr, addr + size,
336 VM_PROT_ALL, VM_PROT_ALL, 0);
337
338 /*
339 * Assert: vm_map_insert() will never be able to extend the
340 * previous entry so vm_map_lookup_entry() will find a new
341 * entry exactly corresponding to this address range and it
342 * will have wired_count == 0.
343 */
344 found = vm_map_lookup_entry(map, addr, &entry);
345 KASSERT(found && entry->start == addr && entry->end == addr + size &&
346 entry->wired_count == 0 && (entry->eflags & MAP_ENTRY_IN_TRANSITION)
347 == 0, ("kmem_back: entry not found or misaligned"));
348
349 if ((flags & (M_NOWAIT|M_USE_RESERVE)) == M_NOWAIT)
350 pflags = VM_ALLOC_INTERRUPT | VM_ALLOC_WIRED;
351 else
352 pflags = VM_ALLOC_SYSTEM | VM_ALLOC_WIRED;
353
354 if (flags & M_ZERO)
355 pflags |= VM_ALLOC_ZERO;
356 if (flags & M_NODUMP)
357 pflags |= VM_ALLOC_NODUMP;
358
359 VM_OBJECT_LOCK(kmem_object);
360 for (i = 0; i < size; i += PAGE_SIZE) {
361 retry:
362 m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i), pflags);
363
364 /*
365 * Ran out of space, free everything up and return. Don't need
366 * to lock page queues here as we know that the pages we got
367 * aren't on any queues.
368 */
369 if (m == NULL) {
370 if ((flags & M_NOWAIT) == 0) {
371 VM_OBJECT_UNLOCK(kmem_object);
372 entry->eflags |= MAP_ENTRY_IN_TRANSITION;
373 vm_map_unlock(map);
374 VM_WAIT;
375 vm_map_lock(map);
376 KASSERT(
377 (entry->eflags & (MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_NEEDS_WAKEUP)) ==
378 MAP_ENTRY_IN_TRANSITION,
379 ("kmem_back: volatile entry"));
380 entry->eflags &= ~MAP_ENTRY_IN_TRANSITION;
381 VM_OBJECT_LOCK(kmem_object);
382 goto retry;
383 }
384 /*
385 * Free the pages before removing the map entry.
386 * They are already marked busy. Calling
387 * vm_map_delete before the pages has been freed or
388 * unbusied will cause a deadlock.
389 */
390 while (i != 0) {
391 i -= PAGE_SIZE;
392 m = vm_page_lookup(kmem_object,
393 OFF_TO_IDX(offset + i));
394 vm_page_unwire(m, 0);
395 vm_page_free(m);
396 }
397 VM_OBJECT_UNLOCK(kmem_object);
398 vm_map_delete(map, addr, addr + size);
399 return (KERN_NO_SPACE);
400 }
401 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
402 pmap_zero_page(m);
403 m->valid = VM_PAGE_BITS_ALL;
404 KASSERT((m->oflags & VPO_UNMANAGED) != 0,
405 ("kmem_malloc: page %p is managed", m));
406 }
407 VM_OBJECT_UNLOCK(kmem_object);
408
409 /*
410 * Mark map entry as non-pageable. Repeat the assert.
411 */
412 KASSERT(entry->start == addr && entry->end == addr + size &&
413 entry->wired_count == 0,
414 ("kmem_back: entry not found or misaligned after allocation"));
415 entry->wired_count = 1;
416
417 /*
418 * At this point, the kmem_object must be unlocked because
419 * vm_map_simplify_entry() calls vm_object_deallocate(), which
420 * locks the kmem_object.
421 */
422 vm_map_simplify_entry(map, entry);
423
424 /*
425 * Loop thru pages, entering them in the pmap.
426 */
427 VM_OBJECT_LOCK(kmem_object);
428 for (i = 0; i < size; i += PAGE_SIZE) {
429 m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
430 /*
431 * Because this is kernel_pmap, this call will not block.
432 */
433 pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
434 TRUE);
435 vm_page_wakeup(m);
436 }
437 VM_OBJECT_UNLOCK(kmem_object);
438
439 return (KERN_SUCCESS);
440 }
441
442 /*
443 * kmem_alloc_wait:
444 *
445 * Allocates pageable memory from a sub-map of the kernel. If the submap
446 * has no room, the caller sleeps waiting for more memory in the submap.
447 *
448 * This routine may block.
449 */
450 vm_offset_t
451 kmem_alloc_wait(map, size)
452 vm_map_t map;
453 vm_size_t size;
454 {
455 vm_offset_t addr;
456
457 size = round_page(size);
458 if (!swap_reserve(size))
459 return (0);
460
461 for (;;) {
462 /*
463 * To make this work for more than one map, use the map's lock
464 * to lock out sleepers/wakers.
465 */
466 vm_map_lock(map);
467 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
468 break;
469 /* no space now; see if we can ever get space */
470 if (vm_map_max(map) - vm_map_min(map) < size) {
471 vm_map_unlock(map);
472 swap_release(size);
473 return (0);
474 }
475 map->needs_wakeup = TRUE;
476 vm_map_unlock_and_wait(map, 0);
477 }
478 vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL,
479 VM_PROT_ALL, MAP_ACC_CHARGED);
480 vm_map_unlock(map);
481 return (addr);
482 }
483
484 /*
485 * kmem_free_wakeup:
486 *
487 * Returns memory to a submap of the kernel, and wakes up any processes
488 * waiting for memory in that map.
489 */
490 void
491 kmem_free_wakeup(map, addr, size)
492 vm_map_t map;
493 vm_offset_t addr;
494 vm_size_t size;
495 {
496
497 vm_map_lock(map);
498 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
499 if (map->needs_wakeup) {
500 map->needs_wakeup = FALSE;
501 vm_map_wakeup(map);
502 }
503 vm_map_unlock(map);
504 }
505
506 static void
507 kmem_init_zero_region(void)
508 {
509 vm_offset_t addr, i;
510 vm_page_t m;
511 int error;
512
513 /*
514 * Map a single physical page of zeros to a larger virtual range.
515 * This requires less looping in places that want large amounts of
516 * zeros, while not using much more physical resources.
517 */
518 addr = kmem_alloc_nofault(kernel_map, ZERO_REGION_SIZE);
519 m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
520 VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
521 if ((m->flags & PG_ZERO) == 0)
522 pmap_zero_page(m);
523 for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
524 pmap_qenter(addr + i, &m, 1);
525 error = vm_map_protect(kernel_map, addr, addr + ZERO_REGION_SIZE,
526 VM_PROT_READ, TRUE);
527 KASSERT(error == 0, ("error=%d", error));
528
529 zero_region = (const void *)addr;
530 }
531
532 /*
533 * kmem_init:
534 *
535 * Create the kernel map; insert a mapping covering kernel text,
536 * data, bss, and all space allocated thus far (`boostrap' data). The
537 * new map will thus map the range between VM_MIN_KERNEL_ADDRESS and
538 * `start' as allocated, and the range between `start' and `end' as free.
539 */
540 void
541 kmem_init(start, end)
542 vm_offset_t start, end;
543 {
544 vm_map_t m;
545
546 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
547 m->system_map = 1;
548 vm_map_lock(m);
549 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
550 kernel_map = m;
551 (void) vm_map_insert(m, NULL, (vm_ooffset_t) 0,
552 #ifdef __amd64__
553 KERNBASE,
554 #else
555 VM_MIN_KERNEL_ADDRESS,
556 #endif
557 start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
558 /* ... and ending with the completion of the above `insert' */
559 vm_map_unlock(m);
560
561 kmem_init_zero_region();
562 }
563
564 #ifdef DIAGNOSTIC
565 /*
566 * Allow userspace to directly trigger the VM drain routine for testing
567 * purposes.
568 */
569 static int
570 debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
571 {
572 int error, i;
573
574 i = 0;
575 error = sysctl_handle_int(oidp, &i, 0, req);
576 if (error)
577 return (error);
578 if (i)
579 EVENTHANDLER_INVOKE(vm_lowmem, 0);
580 return (0);
581 }
582
583 SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
584 debug_vm_lowmem, "I", "set to trigger vm_lowmem event");
585 #endif
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