1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/bio.h> 78 #include <sys/blist.h> 79 #include <sys/buf.h> 80 #include <sys/conf.h> 81 #include <sys/disk.h> 82 #include <sys/disklabel.h> 83 #include <sys/eventhandler.h> 84 #include <sys/fcntl.h> 85 #include <sys/lock.h> 86 #include <sys/kernel.h> 87 #include <sys/mount.h> 88 #include <sys/namei.h> 89 #include <sys/malloc.h> 90 #include <sys/pctrie.h> 91 #include <sys/priv.h> 92 #include <sys/proc.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/systm.h> 101 #include <sys/sx.h> 102 #include <sys/vmmeter.h> 103 #include <sys/vnode.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static u_long swap_reserved; 156 static u_long swap_total; 157 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 158 159 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD, 0, "VM swap stats"); 160 161 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 162 &swap_reserved, 0, sysctl_page_shift, "A", 163 "Amount of swap storage needed to back all allocated anonymous memory."); 164 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 165 &swap_total, 0, sysctl_page_shift, "A", 166 "Total amount of available swap storage."); 167 168 static int overcommit = 0; 169 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 170 "Configure virtual memory overcommit behavior. See tuning(7) " 171 "for details."); 172 static unsigned long swzone; 173 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 174 "Actual size of swap metadata zone"); 175 static unsigned long swap_maxpages; 176 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 177 "Maximum amount of swap supported"); 178 179 static counter_u64_t swap_free_deferred; 180 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 181 CTLFLAG_RD, &swap_free_deferred, 182 "Number of pages that deferred freeing swap space"); 183 184 static counter_u64_t swap_free_completed; 185 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 186 CTLFLAG_RD, &swap_free_completed, 187 "Number of deferred frees completed"); 188 189 /* bits from overcommit */ 190 #define SWAP_RESERVE_FORCE_ON (1 << 0) 191 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 192 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 193 194 static int 195 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 196 { 197 uint64_t newval; 198 u_long value = *(u_long *)arg1; 199 200 newval = ((uint64_t)value) << PAGE_SHIFT; 201 return (sysctl_handle_64(oidp, &newval, 0, req)); 202 } 203 204 int 205 swap_reserve(vm_ooffset_t incr) 206 { 207 208 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 209 } 210 211 int 212 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 213 { 214 u_long r, s, prev, pincr; 215 int res, error; 216 static int curfail; 217 static struct timeval lastfail; 218 struct uidinfo *uip; 219 220 uip = cred->cr_ruidinfo; 221 222 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 223 (uintmax_t)incr)); 224 225 #ifdef RACCT 226 if (racct_enable) { 227 PROC_LOCK(curproc); 228 error = racct_add(curproc, RACCT_SWAP, incr); 229 PROC_UNLOCK(curproc); 230 if (error != 0) 231 return (0); 232 } 233 #endif 234 235 pincr = atop(incr); 236 res = 0; 237 prev = atomic_fetchadd_long(&swap_reserved, pincr); 238 r = prev + pincr; 239 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 240 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 241 vm_wire_count(); 242 } else 243 s = 0; 244 s += swap_total; 245 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 246 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 247 res = 1; 248 } else { 249 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 250 if (prev < pincr) 251 panic("swap_reserved < incr on overcommit fail"); 252 } 253 if (res) { 254 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 255 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 256 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 257 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 258 res = 0; 259 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 260 if (prev < pincr) 261 panic("uip->ui_vmsize < incr on overcommit fail"); 262 } 263 } 264 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 265 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 266 uip->ui_uid, curproc->p_pid, incr); 267 } 268 269 #ifdef RACCT 270 if (racct_enable && !res) { 271 PROC_LOCK(curproc); 272 racct_sub(curproc, RACCT_SWAP, incr); 273 PROC_UNLOCK(curproc); 274 } 275 #endif 276 277 return (res); 278 } 279 280 void 281 swap_reserve_force(vm_ooffset_t incr) 282 { 283 struct uidinfo *uip; 284 u_long pincr; 285 286 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 287 (uintmax_t)incr)); 288 289 PROC_LOCK(curproc); 290 #ifdef RACCT 291 if (racct_enable) 292 racct_add_force(curproc, RACCT_SWAP, incr); 293 #endif 294 pincr = atop(incr); 295 atomic_add_long(&swap_reserved, pincr); 296 uip = curproc->p_ucred->cr_ruidinfo; 297 atomic_add_long(&uip->ui_vmsize, pincr); 298 PROC_UNLOCK(curproc); 299 } 300 301 void 302 swap_release(vm_ooffset_t decr) 303 { 304 struct ucred *cred; 305 306 PROC_LOCK(curproc); 307 cred = curproc->p_ucred; 308 swap_release_by_cred(decr, cred); 309 PROC_UNLOCK(curproc); 310 } 311 312 void 313 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 314 { 315 u_long prev, pdecr; 316 struct uidinfo *uip; 317 318 uip = cred->cr_ruidinfo; 319 320 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 321 (uintmax_t)decr)); 322 323 pdecr = atop(decr); 324 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 325 if (prev < pdecr) 326 panic("swap_reserved < decr"); 327 328 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 329 if (prev < pdecr) 330 printf("negative vmsize for uid = %d\n", uip->ui_uid); 331 #ifdef RACCT 332 if (racct_enable) 333 racct_sub_cred(cred, RACCT_SWAP, decr); 334 #endif 335 } 336 337 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 338 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 339 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 340 static int nsw_wcount_async; /* limit async write buffers */ 341 static int nsw_wcount_async_max;/* assigned maximum */ 342 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 343 344 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 345 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 346 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 347 "Maximum running async swap ops"); 348 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 349 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 350 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 351 "Swap Fragmentation Info"); 352 353 static struct sx sw_alloc_sx; 354 355 /* 356 * "named" and "unnamed" anon region objects. Try to reduce the overhead 357 * of searching a named list by hashing it just a little. 358 */ 359 360 #define NOBJLISTS 8 361 362 #define NOBJLIST(handle) \ 363 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 364 365 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 366 static uma_zone_t swwbuf_zone; 367 static uma_zone_t swrbuf_zone; 368 static uma_zone_t swblk_zone; 369 static uma_zone_t swpctrie_zone; 370 371 /* 372 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 373 * calls hooked from other parts of the VM system and do not appear here. 374 * (see vm/swap_pager.h). 375 */ 376 static vm_object_t 377 swap_pager_alloc(void *handle, vm_ooffset_t size, 378 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 379 static void swap_pager_dealloc(vm_object_t object); 380 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 381 int *); 382 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 383 int *, pgo_getpages_iodone_t, void *); 384 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 385 static boolean_t 386 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 387 static void swap_pager_init(void); 388 static void swap_pager_unswapped(vm_page_t); 389 static void swap_pager_swapoff(struct swdevt *sp); 390 static void swap_pager_update_writecount(vm_object_t object, 391 vm_offset_t start, vm_offset_t end); 392 static void swap_pager_release_writecount(vm_object_t object, 393 vm_offset_t start, vm_offset_t end); 394 395 struct pagerops swappagerops = { 396 .pgo_init = swap_pager_init, /* early system initialization of pager */ 397 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 398 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 399 .pgo_getpages = swap_pager_getpages, /* pagein */ 400 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 401 .pgo_putpages = swap_pager_putpages, /* pageout */ 402 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 403 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 404 .pgo_update_writecount = swap_pager_update_writecount, 405 .pgo_release_writecount = swap_pager_release_writecount, 406 }; 407 408 /* 409 * swap_*() routines are externally accessible. swp_*() routines are 410 * internal. 411 */ 412 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 413 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 414 415 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 416 "Maximum size of a swap block in pages"); 417 418 static void swp_sizecheck(void); 419 static void swp_pager_async_iodone(struct buf *bp); 420 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 421 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 422 static int swapongeom(struct vnode *); 423 static int swaponvp(struct thread *, struct vnode *, u_long); 424 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 425 426 /* 427 * Swap bitmap functions 428 */ 429 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 430 static daddr_t swp_pager_getswapspace(int *npages, int limit); 431 432 /* 433 * Metadata functions 434 */ 435 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 436 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 437 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 438 vm_pindex_t pindex, vm_pindex_t count); 439 static void swp_pager_meta_free_all(vm_object_t); 440 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 441 442 static void 443 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 444 { 445 446 *start = SWAPBLK_NONE; 447 *num = 0; 448 } 449 450 static void 451 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 452 { 453 454 if (*start + *num == addr) { 455 (*num)++; 456 } else { 457 swp_pager_freeswapspace(*start, *num); 458 *start = addr; 459 *num = 1; 460 } 461 } 462 463 static void * 464 swblk_trie_alloc(struct pctrie *ptree) 465 { 466 467 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 468 M_USE_RESERVE : 0))); 469 } 470 471 static void 472 swblk_trie_free(struct pctrie *ptree, void *node) 473 { 474 475 uma_zfree(swpctrie_zone, node); 476 } 477 478 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 479 480 /* 481 * SWP_SIZECHECK() - update swap_pager_full indication 482 * 483 * update the swap_pager_almost_full indication and warn when we are 484 * about to run out of swap space, using lowat/hiwat hysteresis. 485 * 486 * Clear swap_pager_full ( task killing ) indication when lowat is met. 487 * 488 * No restrictions on call 489 * This routine may not block. 490 */ 491 static void 492 swp_sizecheck(void) 493 { 494 495 if (swap_pager_avail < nswap_lowat) { 496 if (swap_pager_almost_full == 0) { 497 printf("swap_pager: out of swap space\n"); 498 swap_pager_almost_full = 1; 499 } 500 } else { 501 swap_pager_full = 0; 502 if (swap_pager_avail > nswap_hiwat) 503 swap_pager_almost_full = 0; 504 } 505 } 506 507 /* 508 * SWAP_PAGER_INIT() - initialize the swap pager! 509 * 510 * Expected to be started from system init. NOTE: This code is run 511 * before much else so be careful what you depend on. Most of the VM 512 * system has yet to be initialized at this point. 513 */ 514 static void 515 swap_pager_init(void) 516 { 517 /* 518 * Initialize object lists 519 */ 520 int i; 521 522 for (i = 0; i < NOBJLISTS; ++i) 523 TAILQ_INIT(&swap_pager_object_list[i]); 524 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 525 sx_init(&sw_alloc_sx, "swspsx"); 526 sx_init(&swdev_syscall_lock, "swsysc"); 527 } 528 529 static void 530 swap_pager_counters(void) 531 { 532 533 swap_free_deferred = counter_u64_alloc(M_WAITOK); 534 swap_free_completed = counter_u64_alloc(M_WAITOK); 535 } 536 SYSINIT(swap_counters, SI_SUB_CPU, SI_ORDER_ANY, swap_pager_counters, NULL); 537 538 /* 539 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 540 * 541 * Expected to be started from pageout process once, prior to entering 542 * its main loop. 543 */ 544 void 545 swap_pager_swap_init(void) 546 { 547 unsigned long n, n2; 548 549 /* 550 * Number of in-transit swap bp operations. Don't 551 * exhaust the pbufs completely. Make sure we 552 * initialize workable values (0 will work for hysteresis 553 * but it isn't very efficient). 554 * 555 * The nsw_cluster_max is constrained by the bp->b_pages[] 556 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 557 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 558 * constrained by the swap device interleave stripe size. 559 * 560 * Currently we hardwire nsw_wcount_async to 4. This limit is 561 * designed to prevent other I/O from having high latencies due to 562 * our pageout I/O. The value 4 works well for one or two active swap 563 * devices but is probably a little low if you have more. Even so, 564 * a higher value would probably generate only a limited improvement 565 * with three or four active swap devices since the system does not 566 * typically have to pageout at extreme bandwidths. We will want 567 * at least 2 per swap devices, and 4 is a pretty good value if you 568 * have one NFS swap device due to the command/ack latency over NFS. 569 * So it all works out pretty well. 570 */ 571 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 572 573 nsw_wcount_async = 4; 574 nsw_wcount_async_max = nsw_wcount_async; 575 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 576 577 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 578 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 579 580 /* 581 * Initialize our zone, taking the user's requested size or 582 * estimating the number we need based on the number of pages 583 * in the system. 584 */ 585 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 586 vm_cnt.v_page_count / 2; 587 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 588 pctrie_zone_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM); 589 if (swpctrie_zone == NULL) 590 panic("failed to create swap pctrie zone."); 591 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 592 NULL, NULL, _Alignof(struct swblk) - 1, UMA_ZONE_VM); 593 if (swblk_zone == NULL) 594 panic("failed to create swap blk zone."); 595 n2 = n; 596 do { 597 if (uma_zone_reserve_kva(swblk_zone, n)) 598 break; 599 /* 600 * if the allocation failed, try a zone two thirds the 601 * size of the previous attempt. 602 */ 603 n -= ((n + 2) / 3); 604 } while (n > 0); 605 606 /* 607 * Often uma_zone_reserve_kva() cannot reserve exactly the 608 * requested size. Account for the difference when 609 * calculating swap_maxpages. 610 */ 611 n = uma_zone_get_max(swblk_zone); 612 613 if (n < n2) 614 printf("Swap blk zone entries changed from %lu to %lu.\n", 615 n2, n); 616 /* absolute maximum we can handle assuming 100% efficiency */ 617 swap_maxpages = n * SWAP_META_PAGES; 618 swzone = n * sizeof(struct swblk); 619 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 620 printf("Cannot reserve swap pctrie zone, " 621 "reduce kern.maxswzone.\n"); 622 } 623 624 static vm_object_t 625 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 626 vm_ooffset_t offset) 627 { 628 vm_object_t object; 629 630 if (cred != NULL) { 631 if (!swap_reserve_by_cred(size, cred)) 632 return (NULL); 633 crhold(cred); 634 } 635 636 /* 637 * The un_pager.swp.swp_blks trie is initialized by 638 * vm_object_allocate() to ensure the correct order of 639 * visibility to other threads. 640 */ 641 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 642 PAGE_MASK + size)); 643 644 object->un_pager.swp.writemappings = 0; 645 object->handle = handle; 646 if (cred != NULL) { 647 object->cred = cred; 648 object->charge = size; 649 } 650 return (object); 651 } 652 653 /* 654 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 655 * its metadata structures. 656 * 657 * This routine is called from the mmap and fork code to create a new 658 * OBJT_SWAP object. 659 * 660 * This routine must ensure that no live duplicate is created for 661 * the named object request, which is protected against by 662 * holding the sw_alloc_sx lock in case handle != NULL. 663 */ 664 static vm_object_t 665 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 666 vm_ooffset_t offset, struct ucred *cred) 667 { 668 vm_object_t object; 669 670 if (handle != NULL) { 671 /* 672 * Reference existing named region or allocate new one. There 673 * should not be a race here against swp_pager_meta_build() 674 * as called from vm_page_remove() in regards to the lookup 675 * of the handle. 676 */ 677 sx_xlock(&sw_alloc_sx); 678 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 679 if (object == NULL) { 680 object = swap_pager_alloc_init(handle, cred, size, 681 offset); 682 if (object != NULL) { 683 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 684 object, pager_object_list); 685 } 686 } 687 sx_xunlock(&sw_alloc_sx); 688 } else { 689 object = swap_pager_alloc_init(handle, cred, size, offset); 690 } 691 return (object); 692 } 693 694 /* 695 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 696 * 697 * The swap backing for the object is destroyed. The code is 698 * designed such that we can reinstantiate it later, but this 699 * routine is typically called only when the entire object is 700 * about to be destroyed. 701 * 702 * The object must be locked. 703 */ 704 static void 705 swap_pager_dealloc(vm_object_t object) 706 { 707 708 VM_OBJECT_ASSERT_WLOCKED(object); 709 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 710 711 /* 712 * Remove from list right away so lookups will fail if we block for 713 * pageout completion. 714 */ 715 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 716 VM_OBJECT_WUNLOCK(object); 717 sx_xlock(&sw_alloc_sx); 718 TAILQ_REMOVE(NOBJLIST(object->handle), object, 719 pager_object_list); 720 sx_xunlock(&sw_alloc_sx); 721 VM_OBJECT_WLOCK(object); 722 } 723 724 vm_object_pip_wait(object, "swpdea"); 725 726 /* 727 * Free all remaining metadata. We only bother to free it from 728 * the swap meta data. We do not attempt to free swapblk's still 729 * associated with vm_page_t's for this object. We do not care 730 * if paging is still in progress on some objects. 731 */ 732 swp_pager_meta_free_all(object); 733 object->handle = NULL; 734 object->type = OBJT_DEAD; 735 } 736 737 /************************************************************************ 738 * SWAP PAGER BITMAP ROUTINES * 739 ************************************************************************/ 740 741 /* 742 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 743 * 744 * Allocate swap for up to the requested number of pages, and at 745 * least a minimum number of pages. The starting swap block number 746 * (a page index) is returned or SWAPBLK_NONE if the allocation 747 * failed. 748 * 749 * Also has the side effect of advising that somebody made a mistake 750 * when they configured swap and didn't configure enough. 751 * 752 * This routine may not sleep. 753 * 754 * We allocate in round-robin fashion from the configured devices. 755 */ 756 static daddr_t 757 swp_pager_getswapspace(int *io_npages, int limit) 758 { 759 daddr_t blk; 760 struct swdevt *sp; 761 int mpages, npages; 762 763 blk = SWAPBLK_NONE; 764 mpages = *io_npages; 765 npages = imin(BLIST_MAX_ALLOC, mpages); 766 mtx_lock(&sw_dev_mtx); 767 sp = swdevhd; 768 while (!TAILQ_EMPTY(&swtailq)) { 769 if (sp == NULL) 770 sp = TAILQ_FIRST(&swtailq); 771 if ((sp->sw_flags & SW_CLOSING) == 0) 772 blk = blist_alloc(sp->sw_blist, &npages, mpages); 773 if (blk != SWAPBLK_NONE) 774 break; 775 sp = TAILQ_NEXT(sp, sw_list); 776 if (swdevhd == sp) { 777 if (npages <= limit) 778 break; 779 mpages = npages - 1; 780 npages >>= 1; 781 } 782 } 783 if (blk != SWAPBLK_NONE) { 784 *io_npages = npages; 785 blk += sp->sw_first; 786 sp->sw_used += npages; 787 swap_pager_avail -= npages; 788 swp_sizecheck(); 789 swdevhd = TAILQ_NEXT(sp, sw_list); 790 } else { 791 if (swap_pager_full != 2) { 792 printf("swp_pager_getswapspace(%d): failed\n", 793 *io_npages); 794 swap_pager_full = 2; 795 swap_pager_almost_full = 1; 796 } 797 swdevhd = NULL; 798 } 799 mtx_unlock(&sw_dev_mtx); 800 return (blk); 801 } 802 803 static bool 804 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 805 { 806 807 return (blk >= sp->sw_first && blk < sp->sw_end); 808 } 809 810 static void 811 swp_pager_strategy(struct buf *bp) 812 { 813 struct swdevt *sp; 814 815 mtx_lock(&sw_dev_mtx); 816 TAILQ_FOREACH(sp, &swtailq, sw_list) { 817 if (swp_pager_isondev(bp->b_blkno, sp)) { 818 mtx_unlock(&sw_dev_mtx); 819 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 820 unmapped_buf_allowed) { 821 bp->b_data = unmapped_buf; 822 bp->b_offset = 0; 823 } else { 824 pmap_qenter((vm_offset_t)bp->b_data, 825 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 826 } 827 sp->sw_strategy(bp, sp); 828 return; 829 } 830 } 831 panic("Swapdev not found"); 832 } 833 834 835 /* 836 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 837 * 838 * This routine returns the specified swap blocks back to the bitmap. 839 * 840 * This routine may not sleep. 841 */ 842 static void 843 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 844 { 845 struct swdevt *sp; 846 847 if (npages == 0) 848 return; 849 mtx_lock(&sw_dev_mtx); 850 TAILQ_FOREACH(sp, &swtailq, sw_list) { 851 if (swp_pager_isondev(blk, sp)) { 852 sp->sw_used -= npages; 853 /* 854 * If we are attempting to stop swapping on 855 * this device, we don't want to mark any 856 * blocks free lest they be reused. 857 */ 858 if ((sp->sw_flags & SW_CLOSING) == 0) { 859 blist_free(sp->sw_blist, blk - sp->sw_first, 860 npages); 861 swap_pager_avail += npages; 862 swp_sizecheck(); 863 } 864 mtx_unlock(&sw_dev_mtx); 865 return; 866 } 867 } 868 panic("Swapdev not found"); 869 } 870 871 /* 872 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 873 */ 874 static int 875 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 876 { 877 struct sbuf sbuf; 878 struct swdevt *sp; 879 const char *devname; 880 int error; 881 882 error = sysctl_wire_old_buffer(req, 0); 883 if (error != 0) 884 return (error); 885 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 886 mtx_lock(&sw_dev_mtx); 887 TAILQ_FOREACH(sp, &swtailq, sw_list) { 888 if (vn_isdisk(sp->sw_vp, NULL)) 889 devname = devtoname(sp->sw_vp->v_rdev); 890 else 891 devname = "[file]"; 892 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 893 blist_stats(sp->sw_blist, &sbuf); 894 } 895 mtx_unlock(&sw_dev_mtx); 896 error = sbuf_finish(&sbuf); 897 sbuf_delete(&sbuf); 898 return (error); 899 } 900 901 /* 902 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 903 * range within an object. 904 * 905 * This is a globally accessible routine. 906 * 907 * This routine removes swapblk assignments from swap metadata. 908 * 909 * The external callers of this routine typically have already destroyed 910 * or renamed vm_page_t's associated with this range in the object so 911 * we should be ok. 912 * 913 * The object must be locked. 914 */ 915 void 916 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 917 { 918 919 swp_pager_meta_free(object, start, size); 920 } 921 922 /* 923 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 924 * 925 * Assigns swap blocks to the specified range within the object. The 926 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 927 * 928 * Returns 0 on success, -1 on failure. 929 */ 930 int 931 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 932 { 933 daddr_t addr, blk, n_free, s_free; 934 int i, j, n; 935 936 swp_pager_init_freerange(&s_free, &n_free); 937 VM_OBJECT_WLOCK(object); 938 for (i = 0; i < size; i += n) { 939 n = size - i; 940 blk = swp_pager_getswapspace(&n, 1); 941 if (blk == SWAPBLK_NONE) { 942 swp_pager_meta_free(object, start, i); 943 VM_OBJECT_WUNLOCK(object); 944 return (-1); 945 } 946 for (j = 0; j < n; ++j) { 947 addr = swp_pager_meta_build(object, 948 start + i + j, blk + j); 949 if (addr != SWAPBLK_NONE) 950 swp_pager_update_freerange(&s_free, &n_free, 951 addr); 952 } 953 } 954 swp_pager_freeswapspace(s_free, n_free); 955 VM_OBJECT_WUNLOCK(object); 956 return (0); 957 } 958 959 static bool 960 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 961 vm_pindex_t pindex, daddr_t addr) 962 { 963 daddr_t dstaddr; 964 965 KASSERT(srcobject->type == OBJT_SWAP, 966 ("%s: Srcobject not swappable", __func__)); 967 if (dstobject->type == OBJT_SWAP && 968 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 969 /* Caller should destroy the source block. */ 970 return (false); 971 } 972 973 /* 974 * Destination has no swapblk and is not resident, transfer source. 975 * swp_pager_meta_build() can sleep. 976 */ 977 VM_OBJECT_WUNLOCK(srcobject); 978 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 979 KASSERT(dstaddr == SWAPBLK_NONE, 980 ("Unexpected destination swapblk")); 981 VM_OBJECT_WLOCK(srcobject); 982 983 return (true); 984 } 985 986 /* 987 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 988 * and destroy the source. 989 * 990 * Copy any valid swapblks from the source to the destination. In 991 * cases where both the source and destination have a valid swapblk, 992 * we keep the destination's. 993 * 994 * This routine is allowed to sleep. It may sleep allocating metadata 995 * indirectly through swp_pager_meta_build(). 996 * 997 * The source object contains no vm_page_t's (which is just as well) 998 * 999 * The source object is of type OBJT_SWAP. 1000 * 1001 * The source and destination objects must be locked. 1002 * Both object locks may temporarily be released. 1003 */ 1004 void 1005 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1006 vm_pindex_t offset, int destroysource) 1007 { 1008 1009 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1010 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1011 1012 /* 1013 * If destroysource is set, we remove the source object from the 1014 * swap_pager internal queue now. 1015 */ 1016 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1017 srcobject->handle != NULL) { 1018 VM_OBJECT_WUNLOCK(srcobject); 1019 VM_OBJECT_WUNLOCK(dstobject); 1020 sx_xlock(&sw_alloc_sx); 1021 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1022 pager_object_list); 1023 sx_xunlock(&sw_alloc_sx); 1024 VM_OBJECT_WLOCK(dstobject); 1025 VM_OBJECT_WLOCK(srcobject); 1026 } 1027 1028 /* 1029 * Transfer source to destination. 1030 */ 1031 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1032 1033 /* 1034 * Free left over swap blocks in source. 1035 * 1036 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1037 * double-remove the object from the swap queues. 1038 */ 1039 if (destroysource) { 1040 swp_pager_meta_free_all(srcobject); 1041 /* 1042 * Reverting the type is not necessary, the caller is going 1043 * to destroy srcobject directly, but I'm doing it here 1044 * for consistency since we've removed the object from its 1045 * queues. 1046 */ 1047 srcobject->type = OBJT_DEFAULT; 1048 } 1049 } 1050 1051 /* 1052 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1053 * the requested page. 1054 * 1055 * We determine whether good backing store exists for the requested 1056 * page and return TRUE if it does, FALSE if it doesn't. 1057 * 1058 * If TRUE, we also try to determine how much valid, contiguous backing 1059 * store exists before and after the requested page. 1060 */ 1061 static boolean_t 1062 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1063 int *after) 1064 { 1065 daddr_t blk, blk0; 1066 int i; 1067 1068 VM_OBJECT_ASSERT_LOCKED(object); 1069 KASSERT(object->type == OBJT_SWAP, 1070 ("%s: object not swappable", __func__)); 1071 1072 /* 1073 * do we have good backing store at the requested index ? 1074 */ 1075 blk0 = swp_pager_meta_lookup(object, pindex); 1076 if (blk0 == SWAPBLK_NONE) { 1077 if (before) 1078 *before = 0; 1079 if (after) 1080 *after = 0; 1081 return (FALSE); 1082 } 1083 1084 /* 1085 * find backwards-looking contiguous good backing store 1086 */ 1087 if (before != NULL) { 1088 for (i = 1; i < SWB_NPAGES; i++) { 1089 if (i > pindex) 1090 break; 1091 blk = swp_pager_meta_lookup(object, pindex - i); 1092 if (blk != blk0 - i) 1093 break; 1094 } 1095 *before = i - 1; 1096 } 1097 1098 /* 1099 * find forward-looking contiguous good backing store 1100 */ 1101 if (after != NULL) { 1102 for (i = 1; i < SWB_NPAGES; i++) { 1103 blk = swp_pager_meta_lookup(object, pindex + i); 1104 if (blk != blk0 + i) 1105 break; 1106 } 1107 *after = i - 1; 1108 } 1109 return (TRUE); 1110 } 1111 1112 /* 1113 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1114 * 1115 * This removes any associated swap backing store, whether valid or 1116 * not, from the page. 1117 * 1118 * This routine is typically called when a page is made dirty, at 1119 * which point any associated swap can be freed. MADV_FREE also 1120 * calls us in a special-case situation 1121 * 1122 * NOTE!!! If the page is clean and the swap was valid, the caller 1123 * should make the page dirty before calling this routine. This routine 1124 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1125 * depends on it. 1126 * 1127 * This routine may not sleep. 1128 * 1129 * The object containing the page may be locked. 1130 */ 1131 static void 1132 swap_pager_unswapped(vm_page_t m) 1133 { 1134 struct swblk *sb; 1135 vm_object_t obj; 1136 1137 /* 1138 * Handle enqueing deferred frees first. If we do not have the 1139 * object lock we wait for the page daemon to clear the space. 1140 */ 1141 obj = m->object; 1142 if (!VM_OBJECT_WOWNED(obj)) { 1143 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1144 /* 1145 * The caller is responsible for synchronization but we 1146 * will harmlessly handle races. This is typically provided 1147 * by only calling unswapped() when a page transitions from 1148 * clean to dirty. 1149 */ 1150 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1151 PGA_SWAP_SPACE) { 1152 vm_page_aflag_set(m, PGA_SWAP_FREE); 1153 counter_u64_add(swap_free_deferred, 1); 1154 } 1155 return; 1156 } 1157 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1158 counter_u64_add(swap_free_completed, 1); 1159 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1160 1161 /* 1162 * The meta data only exists if the object is OBJT_SWAP 1163 * and even then might not be allocated yet. 1164 */ 1165 KASSERT(m->object->type == OBJT_SWAP, 1166 ("Free object not swappable")); 1167 1168 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1169 rounddown(m->pindex, SWAP_META_PAGES)); 1170 if (sb == NULL) 1171 return; 1172 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1173 return; 1174 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1175 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1176 swp_pager_free_empty_swblk(m->object, sb); 1177 } 1178 1179 /* 1180 * swap_pager_getpages() - bring pages in from swap 1181 * 1182 * Attempt to page in the pages in array "ma" of length "count". The 1183 * caller may optionally specify that additional pages preceding and 1184 * succeeding the specified range be paged in. The number of such pages 1185 * is returned in the "rbehind" and "rahead" parameters, and they will 1186 * be in the inactive queue upon return. 1187 * 1188 * The pages in "ma" must be busied and will remain busied upon return. 1189 */ 1190 static int 1191 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1192 int *rbehind, int *rahead) 1193 { 1194 struct buf *bp; 1195 vm_page_t bm, mpred, msucc, p; 1196 vm_pindex_t pindex; 1197 daddr_t blk; 1198 int i, maxahead, maxbehind, reqcount; 1199 1200 VM_OBJECT_ASSERT_WLOCKED(object); 1201 reqcount = count; 1202 1203 KASSERT(object->type == OBJT_SWAP, 1204 ("%s: object not swappable", __func__)); 1205 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1206 VM_OBJECT_WUNLOCK(object); 1207 return (VM_PAGER_FAIL); 1208 } 1209 1210 KASSERT(reqcount - 1 <= maxahead, 1211 ("page count %d extends beyond swap block", reqcount)); 1212 1213 /* 1214 * Do not transfer any pages other than those that are xbusied 1215 * when running during a split or collapse operation. This 1216 * prevents clustering from re-creating pages which are being 1217 * moved into another object. 1218 */ 1219 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1220 maxahead = reqcount - 1; 1221 maxbehind = 0; 1222 } 1223 1224 /* 1225 * Clip the readahead and readbehind ranges to exclude resident pages. 1226 */ 1227 if (rahead != NULL) { 1228 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1229 pindex = ma[reqcount - 1]->pindex; 1230 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1231 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1232 *rahead = msucc->pindex - pindex - 1; 1233 } 1234 if (rbehind != NULL) { 1235 *rbehind = imin(*rbehind, maxbehind); 1236 pindex = ma[0]->pindex; 1237 mpred = TAILQ_PREV(ma[0], pglist, listq); 1238 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1239 *rbehind = pindex - mpred->pindex - 1; 1240 } 1241 1242 bm = ma[0]; 1243 for (i = 0; i < count; i++) 1244 ma[i]->oflags |= VPO_SWAPINPROG; 1245 1246 /* 1247 * Allocate readahead and readbehind pages. 1248 */ 1249 if (rbehind != NULL) { 1250 for (i = 1; i <= *rbehind; i++) { 1251 p = vm_page_alloc(object, ma[0]->pindex - i, 1252 VM_ALLOC_NORMAL); 1253 if (p == NULL) 1254 break; 1255 p->oflags |= VPO_SWAPINPROG; 1256 bm = p; 1257 } 1258 *rbehind = i - 1; 1259 } 1260 if (rahead != NULL) { 1261 for (i = 0; i < *rahead; i++) { 1262 p = vm_page_alloc(object, 1263 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1264 if (p == NULL) 1265 break; 1266 p->oflags |= VPO_SWAPINPROG; 1267 } 1268 *rahead = i; 1269 } 1270 if (rbehind != NULL) 1271 count += *rbehind; 1272 if (rahead != NULL) 1273 count += *rahead; 1274 1275 vm_object_pip_add(object, count); 1276 1277 pindex = bm->pindex; 1278 blk = swp_pager_meta_lookup(object, pindex); 1279 KASSERT(blk != SWAPBLK_NONE, 1280 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1281 1282 VM_OBJECT_WUNLOCK(object); 1283 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1284 /* Pages cannot leave the object while busy. */ 1285 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1286 MPASS(p->pindex == bm->pindex + i); 1287 bp->b_pages[i] = p; 1288 } 1289 1290 bp->b_flags |= B_PAGING; 1291 bp->b_iocmd = BIO_READ; 1292 bp->b_iodone = swp_pager_async_iodone; 1293 bp->b_rcred = crhold(thread0.td_ucred); 1294 bp->b_wcred = crhold(thread0.td_ucred); 1295 bp->b_blkno = blk; 1296 bp->b_bcount = PAGE_SIZE * count; 1297 bp->b_bufsize = PAGE_SIZE * count; 1298 bp->b_npages = count; 1299 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1300 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1301 1302 VM_CNT_INC(v_swapin); 1303 VM_CNT_ADD(v_swappgsin, count); 1304 1305 /* 1306 * perform the I/O. NOTE!!! bp cannot be considered valid after 1307 * this point because we automatically release it on completion. 1308 * Instead, we look at the one page we are interested in which we 1309 * still hold a lock on even through the I/O completion. 1310 * 1311 * The other pages in our ma[] array are also released on completion, 1312 * so we cannot assume they are valid anymore either. 1313 * 1314 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1315 */ 1316 BUF_KERNPROC(bp); 1317 swp_pager_strategy(bp); 1318 1319 /* 1320 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1321 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1322 * is set in the metadata for each page in the request. 1323 */ 1324 VM_OBJECT_WLOCK(object); 1325 /* This could be implemented more efficiently with aflags */ 1326 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1327 ma[0]->oflags |= VPO_SWAPSLEEP; 1328 VM_CNT_INC(v_intrans); 1329 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1330 "swread", hz * 20)) { 1331 printf( 1332 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1333 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1334 } 1335 } 1336 VM_OBJECT_WUNLOCK(object); 1337 1338 /* 1339 * If we had an unrecoverable read error pages will not be valid. 1340 */ 1341 for (i = 0; i < reqcount; i++) 1342 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1343 return (VM_PAGER_ERROR); 1344 1345 return (VM_PAGER_OK); 1346 1347 /* 1348 * A final note: in a low swap situation, we cannot deallocate swap 1349 * and mark a page dirty here because the caller is likely to mark 1350 * the page clean when we return, causing the page to possibly revert 1351 * to all-zero's later. 1352 */ 1353 } 1354 1355 static int 1356 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1357 int *rbehind, int *rahead) 1358 { 1359 1360 VM_OBJECT_WLOCK(object); 1361 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1362 } 1363 1364 /* 1365 * swap_pager_getpages_async(): 1366 * 1367 * Right now this is emulation of asynchronous operation on top of 1368 * swap_pager_getpages(). 1369 */ 1370 static int 1371 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1372 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1373 { 1374 int r, error; 1375 1376 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1377 switch (r) { 1378 case VM_PAGER_OK: 1379 error = 0; 1380 break; 1381 case VM_PAGER_ERROR: 1382 error = EIO; 1383 break; 1384 case VM_PAGER_FAIL: 1385 error = EINVAL; 1386 break; 1387 default: 1388 panic("unhandled swap_pager_getpages() error %d", r); 1389 } 1390 (iodone)(arg, ma, count, error); 1391 1392 return (r); 1393 } 1394 1395 /* 1396 * swap_pager_putpages: 1397 * 1398 * Assign swap (if necessary) and initiate I/O on the specified pages. 1399 * 1400 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1401 * are automatically converted to SWAP objects. 1402 * 1403 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1404 * vm_page reservation system coupled with properly written VFS devices 1405 * should ensure that no low-memory deadlock occurs. This is an area 1406 * which needs work. 1407 * 1408 * The parent has N vm_object_pip_add() references prior to 1409 * calling us and will remove references for rtvals[] that are 1410 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1411 * completion. 1412 * 1413 * The parent has soft-busy'd the pages it passes us and will unbusy 1414 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1415 * We need to unbusy the rest on I/O completion. 1416 */ 1417 static void 1418 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1419 int flags, int *rtvals) 1420 { 1421 struct buf *bp; 1422 daddr_t addr, blk, n_free, s_free; 1423 vm_page_t mreq; 1424 int i, j, n; 1425 bool async; 1426 1427 KASSERT(count == 0 || ma[0]->object == object, 1428 ("%s: object mismatch %p/%p", 1429 __func__, object, ma[0]->object)); 1430 1431 /* 1432 * Step 1 1433 * 1434 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1435 */ 1436 if (object->type != OBJT_SWAP) { 1437 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1438 KASSERT(addr == SWAPBLK_NONE, 1439 ("unexpected object swap block")); 1440 } 1441 VM_OBJECT_WUNLOCK(object); 1442 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1443 swp_pager_init_freerange(&s_free, &n_free); 1444 1445 /* 1446 * Step 2 1447 * 1448 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1449 * The page is left dirty until the pageout operation completes 1450 * successfully. 1451 */ 1452 for (i = 0; i < count; i += n) { 1453 /* Maximum I/O size is limited by maximum swap block size. */ 1454 n = min(count - i, nsw_cluster_max); 1455 1456 if (async) { 1457 mtx_lock(&swbuf_mtx); 1458 while (nsw_wcount_async == 0) 1459 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1460 "swbufa", 0); 1461 nsw_wcount_async--; 1462 mtx_unlock(&swbuf_mtx); 1463 } 1464 1465 /* Get a block of swap of size up to size n. */ 1466 VM_OBJECT_WLOCK(object); 1467 blk = swp_pager_getswapspace(&n, 4); 1468 if (blk == SWAPBLK_NONE) { 1469 VM_OBJECT_WUNLOCK(object); 1470 mtx_lock(&swbuf_mtx); 1471 if (++nsw_wcount_async == 1) 1472 wakeup(&nsw_wcount_async); 1473 mtx_unlock(&swbuf_mtx); 1474 for (j = 0; j < n; ++j) 1475 rtvals[i + j] = VM_PAGER_FAIL; 1476 continue; 1477 } 1478 for (j = 0; j < n; ++j) { 1479 mreq = ma[i + j]; 1480 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1481 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1482 blk + j); 1483 if (addr != SWAPBLK_NONE) 1484 swp_pager_update_freerange(&s_free, &n_free, 1485 addr); 1486 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1487 mreq->oflags |= VPO_SWAPINPROG; 1488 } 1489 VM_OBJECT_WUNLOCK(object); 1490 1491 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1492 if (async) 1493 bp->b_flags = B_ASYNC; 1494 bp->b_flags |= B_PAGING; 1495 bp->b_iocmd = BIO_WRITE; 1496 1497 bp->b_rcred = crhold(thread0.td_ucred); 1498 bp->b_wcred = crhold(thread0.td_ucred); 1499 bp->b_bcount = PAGE_SIZE * n; 1500 bp->b_bufsize = PAGE_SIZE * n; 1501 bp->b_blkno = blk; 1502 for (j = 0; j < n; j++) 1503 bp->b_pages[j] = ma[i + j]; 1504 bp->b_npages = n; 1505 1506 /* 1507 * Must set dirty range for NFS to work. 1508 */ 1509 bp->b_dirtyoff = 0; 1510 bp->b_dirtyend = bp->b_bcount; 1511 1512 VM_CNT_INC(v_swapout); 1513 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1514 1515 /* 1516 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1517 * can call the async completion routine at the end of a 1518 * synchronous I/O operation. Otherwise, our caller would 1519 * perform duplicate unbusy and wakeup operations on the page 1520 * and object, respectively. 1521 */ 1522 for (j = 0; j < n; j++) 1523 rtvals[i + j] = VM_PAGER_PEND; 1524 1525 /* 1526 * asynchronous 1527 * 1528 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1529 */ 1530 if (async) { 1531 bp->b_iodone = swp_pager_async_iodone; 1532 BUF_KERNPROC(bp); 1533 swp_pager_strategy(bp); 1534 continue; 1535 } 1536 1537 /* 1538 * synchronous 1539 * 1540 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1541 */ 1542 bp->b_iodone = bdone; 1543 swp_pager_strategy(bp); 1544 1545 /* 1546 * Wait for the sync I/O to complete. 1547 */ 1548 bwait(bp, PVM, "swwrt"); 1549 1550 /* 1551 * Now that we are through with the bp, we can call the 1552 * normal async completion, which frees everything up. 1553 */ 1554 swp_pager_async_iodone(bp); 1555 } 1556 swp_pager_freeswapspace(s_free, n_free); 1557 VM_OBJECT_WLOCK(object); 1558 } 1559 1560 /* 1561 * swp_pager_async_iodone: 1562 * 1563 * Completion routine for asynchronous reads and writes from/to swap. 1564 * Also called manually by synchronous code to finish up a bp. 1565 * 1566 * This routine may not sleep. 1567 */ 1568 static void 1569 swp_pager_async_iodone(struct buf *bp) 1570 { 1571 int i; 1572 vm_object_t object = NULL; 1573 1574 /* 1575 * Report error - unless we ran out of memory, in which case 1576 * we've already logged it in swapgeom_strategy(). 1577 */ 1578 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1579 printf( 1580 "swap_pager: I/O error - %s failed; blkno %ld," 1581 "size %ld, error %d\n", 1582 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1583 (long)bp->b_blkno, 1584 (long)bp->b_bcount, 1585 bp->b_error 1586 ); 1587 } 1588 1589 /* 1590 * remove the mapping for kernel virtual 1591 */ 1592 if (buf_mapped(bp)) 1593 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1594 else 1595 bp->b_data = bp->b_kvabase; 1596 1597 if (bp->b_npages) { 1598 object = bp->b_pages[0]->object; 1599 VM_OBJECT_WLOCK(object); 1600 } 1601 1602 /* 1603 * cleanup pages. If an error occurs writing to swap, we are in 1604 * very serious trouble. If it happens to be a disk error, though, 1605 * we may be able to recover by reassigning the swap later on. So 1606 * in this case we remove the m->swapblk assignment for the page 1607 * but do not free it in the rlist. The errornous block(s) are thus 1608 * never reallocated as swap. Redirty the page and continue. 1609 */ 1610 for (i = 0; i < bp->b_npages; ++i) { 1611 vm_page_t m = bp->b_pages[i]; 1612 1613 m->oflags &= ~VPO_SWAPINPROG; 1614 if (m->oflags & VPO_SWAPSLEEP) { 1615 m->oflags &= ~VPO_SWAPSLEEP; 1616 wakeup(&object->handle); 1617 } 1618 1619 /* We always have space after I/O, successful or not. */ 1620 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1621 1622 if (bp->b_ioflags & BIO_ERROR) { 1623 /* 1624 * If an error occurs I'd love to throw the swapblk 1625 * away without freeing it back to swapspace, so it 1626 * can never be used again. But I can't from an 1627 * interrupt. 1628 */ 1629 if (bp->b_iocmd == BIO_READ) { 1630 /* 1631 * NOTE: for reads, m->dirty will probably 1632 * be overridden by the original caller of 1633 * getpages so don't play cute tricks here. 1634 */ 1635 vm_page_invalid(m); 1636 } else { 1637 /* 1638 * If a write error occurs, reactivate page 1639 * so it doesn't clog the inactive list, 1640 * then finish the I/O. 1641 */ 1642 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1643 1644 /* PQ_UNSWAPPABLE? */ 1645 vm_page_activate(m); 1646 vm_page_sunbusy(m); 1647 } 1648 } else if (bp->b_iocmd == BIO_READ) { 1649 /* 1650 * NOTE: for reads, m->dirty will probably be 1651 * overridden by the original caller of getpages so 1652 * we cannot set them in order to free the underlying 1653 * swap in a low-swap situation. I don't think we'd 1654 * want to do that anyway, but it was an optimization 1655 * that existed in the old swapper for a time before 1656 * it got ripped out due to precisely this problem. 1657 */ 1658 KASSERT(!pmap_page_is_mapped(m), 1659 ("swp_pager_async_iodone: page %p is mapped", m)); 1660 KASSERT(m->dirty == 0, 1661 ("swp_pager_async_iodone: page %p is dirty", m)); 1662 1663 vm_page_valid(m); 1664 if (i < bp->b_pgbefore || 1665 i >= bp->b_npages - bp->b_pgafter) 1666 vm_page_readahead_finish(m); 1667 } else { 1668 /* 1669 * For write success, clear the dirty 1670 * status, then finish the I/O ( which decrements the 1671 * busy count and possibly wakes waiter's up ). 1672 * A page is only written to swap after a period of 1673 * inactivity. Therefore, we do not expect it to be 1674 * reused. 1675 */ 1676 KASSERT(!pmap_page_is_write_mapped(m), 1677 ("swp_pager_async_iodone: page %p is not write" 1678 " protected", m)); 1679 vm_page_undirty(m); 1680 vm_page_deactivate_noreuse(m); 1681 vm_page_sunbusy(m); 1682 } 1683 } 1684 1685 /* 1686 * adjust pip. NOTE: the original parent may still have its own 1687 * pip refs on the object. 1688 */ 1689 if (object != NULL) { 1690 vm_object_pip_wakeupn(object, bp->b_npages); 1691 VM_OBJECT_WUNLOCK(object); 1692 } 1693 1694 /* 1695 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1696 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1697 * trigger a KASSERT in relpbuf(). 1698 */ 1699 if (bp->b_vp) { 1700 bp->b_vp = NULL; 1701 bp->b_bufobj = NULL; 1702 } 1703 /* 1704 * release the physical I/O buffer 1705 */ 1706 if (bp->b_flags & B_ASYNC) { 1707 mtx_lock(&swbuf_mtx); 1708 if (++nsw_wcount_async == 1) 1709 wakeup(&nsw_wcount_async); 1710 mtx_unlock(&swbuf_mtx); 1711 } 1712 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1713 } 1714 1715 int 1716 swap_pager_nswapdev(void) 1717 { 1718 1719 return (nswapdev); 1720 } 1721 1722 static void 1723 swp_pager_force_dirty(vm_page_t m) 1724 { 1725 1726 vm_page_dirty(m); 1727 swap_pager_unswapped(m); 1728 vm_page_launder(m); 1729 } 1730 1731 /* 1732 * swap_pager_swapoff_object: 1733 * 1734 * Page in all of the pages that have been paged out for an object 1735 * to a swap device. 1736 */ 1737 static void 1738 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1739 { 1740 struct swblk *sb; 1741 vm_page_t m; 1742 vm_pindex_t pi; 1743 daddr_t blk; 1744 int i, nv, rahead, rv; 1745 1746 KASSERT(object->type == OBJT_SWAP, 1747 ("%s: Object not swappable", __func__)); 1748 1749 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1750 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1751 if ((object->flags & OBJ_DEAD) != 0) { 1752 /* 1753 * Make sure that pending writes finish before 1754 * returning. 1755 */ 1756 vm_object_pip_wait(object, "swpoff"); 1757 swp_pager_meta_free_all(object); 1758 break; 1759 } 1760 for (i = 0; i < SWAP_META_PAGES; i++) { 1761 /* 1762 * Count the number of contiguous valid blocks. 1763 */ 1764 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1765 blk = sb->d[i + nv]; 1766 if (!swp_pager_isondev(blk, sp) || 1767 blk == SWAPBLK_NONE) 1768 break; 1769 } 1770 if (nv == 0) 1771 continue; 1772 1773 /* 1774 * Look for a page corresponding to the first 1775 * valid block and ensure that any pending paging 1776 * operations on it are complete. If the page is valid, 1777 * mark it dirty and free the swap block. Try to batch 1778 * this operation since it may cause sp to be freed, 1779 * meaning that we must restart the scan. Avoid busying 1780 * valid pages since we may block forever on kernel 1781 * stack pages. 1782 */ 1783 m = vm_page_lookup(object, sb->p + i); 1784 if (m == NULL) { 1785 m = vm_page_alloc(object, sb->p + i, 1786 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1787 if (m == NULL) 1788 break; 1789 } else { 1790 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1791 m->oflags |= VPO_SWAPSLEEP; 1792 VM_OBJECT_SLEEP(object, &object->handle, 1793 PSWP, "swpoff", 0); 1794 break; 1795 } 1796 if (vm_page_all_valid(m)) { 1797 do { 1798 swp_pager_force_dirty(m); 1799 } while (--nv > 0 && 1800 (m = vm_page_next(m)) != NULL && 1801 vm_page_all_valid(m) && 1802 (m->oflags & VPO_SWAPINPROG) == 0); 1803 break; 1804 } 1805 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1806 break; 1807 } 1808 1809 vm_object_pip_add(object, 1); 1810 rahead = SWAP_META_PAGES; 1811 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1812 &rahead); 1813 if (rv != VM_PAGER_OK) 1814 panic("%s: read from swap failed: %d", 1815 __func__, rv); 1816 vm_object_pip_wakeupn(object, 1); 1817 VM_OBJECT_WLOCK(object); 1818 vm_page_xunbusy(m); 1819 1820 /* 1821 * The object lock was dropped so we must restart the 1822 * scan of this swap block. Pages paged in during this 1823 * iteration will be marked dirty in a future iteration. 1824 */ 1825 break; 1826 } 1827 if (i == SWAP_META_PAGES) 1828 pi = sb->p + SWAP_META_PAGES; 1829 } 1830 } 1831 1832 /* 1833 * swap_pager_swapoff: 1834 * 1835 * Page in all of the pages that have been paged out to the 1836 * given device. The corresponding blocks in the bitmap must be 1837 * marked as allocated and the device must be flagged SW_CLOSING. 1838 * There may be no processes swapped out to the device. 1839 * 1840 * This routine may block. 1841 */ 1842 static void 1843 swap_pager_swapoff(struct swdevt *sp) 1844 { 1845 vm_object_t object; 1846 int retries; 1847 1848 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1849 1850 retries = 0; 1851 full_rescan: 1852 mtx_lock(&vm_object_list_mtx); 1853 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1854 if (object->type != OBJT_SWAP) 1855 continue; 1856 mtx_unlock(&vm_object_list_mtx); 1857 /* Depends on type-stability. */ 1858 VM_OBJECT_WLOCK(object); 1859 1860 /* 1861 * Dead objects are eventually terminated on their own. 1862 */ 1863 if ((object->flags & OBJ_DEAD) != 0) 1864 goto next_obj; 1865 1866 /* 1867 * Sync with fences placed after pctrie 1868 * initialization. We must not access pctrie below 1869 * unless we checked that our object is swap and not 1870 * dead. 1871 */ 1872 atomic_thread_fence_acq(); 1873 if (object->type != OBJT_SWAP) 1874 goto next_obj; 1875 1876 swap_pager_swapoff_object(sp, object); 1877 next_obj: 1878 VM_OBJECT_WUNLOCK(object); 1879 mtx_lock(&vm_object_list_mtx); 1880 } 1881 mtx_unlock(&vm_object_list_mtx); 1882 1883 if (sp->sw_used) { 1884 /* 1885 * Objects may be locked or paging to the device being 1886 * removed, so we will miss their pages and need to 1887 * make another pass. We have marked this device as 1888 * SW_CLOSING, so the activity should finish soon. 1889 */ 1890 retries++; 1891 if (retries > 100) { 1892 panic("swapoff: failed to locate %d swap blocks", 1893 sp->sw_used); 1894 } 1895 pause("swpoff", hz / 20); 1896 goto full_rescan; 1897 } 1898 EVENTHANDLER_INVOKE(swapoff, sp); 1899 } 1900 1901 /************************************************************************ 1902 * SWAP META DATA * 1903 ************************************************************************ 1904 * 1905 * These routines manipulate the swap metadata stored in the 1906 * OBJT_SWAP object. 1907 * 1908 * Swap metadata is implemented with a global hash and not directly 1909 * linked into the object. Instead the object simply contains 1910 * appropriate tracking counters. 1911 */ 1912 1913 /* 1914 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1915 */ 1916 static bool 1917 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1918 { 1919 int i; 1920 1921 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1922 for (i = start; i < limit; i++) { 1923 if (sb->d[i] != SWAPBLK_NONE) 1924 return (false); 1925 } 1926 return (true); 1927 } 1928 1929 /* 1930 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1931 * 1932 * Nothing is done if the block is still in use. 1933 */ 1934 static void 1935 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1936 { 1937 1938 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1939 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1940 uma_zfree(swblk_zone, sb); 1941 } 1942 } 1943 1944 /* 1945 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1946 * 1947 * We first convert the object to a swap object if it is a default 1948 * object. 1949 * 1950 * The specified swapblk is added to the object's swap metadata. If 1951 * the swapblk is not valid, it is freed instead. Any previously 1952 * assigned swapblk is returned. 1953 */ 1954 static daddr_t 1955 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1956 { 1957 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1958 struct swblk *sb, *sb1; 1959 vm_pindex_t modpi, rdpi; 1960 daddr_t prev_swapblk; 1961 int error, i; 1962 1963 VM_OBJECT_ASSERT_WLOCKED(object); 1964 1965 /* 1966 * Convert default object to swap object if necessary 1967 */ 1968 if (object->type != OBJT_SWAP) { 1969 pctrie_init(&object->un_pager.swp.swp_blks); 1970 1971 /* 1972 * Ensure that swap_pager_swapoff()'s iteration over 1973 * object_list does not see a garbage pctrie. 1974 */ 1975 atomic_thread_fence_rel(); 1976 1977 object->type = OBJT_SWAP; 1978 object->un_pager.swp.writemappings = 0; 1979 KASSERT((object->flags & OBJ_ANON) != 0 || 1980 object->handle == NULL, 1981 ("default pager %p with handle %p", 1982 object, object->handle)); 1983 } 1984 1985 rdpi = rounddown(pindex, SWAP_META_PAGES); 1986 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1987 if (sb == NULL) { 1988 if (swapblk == SWAPBLK_NONE) 1989 return (SWAPBLK_NONE); 1990 for (;;) { 1991 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1992 pageproc ? M_USE_RESERVE : 0)); 1993 if (sb != NULL) { 1994 sb->p = rdpi; 1995 for (i = 0; i < SWAP_META_PAGES; i++) 1996 sb->d[i] = SWAPBLK_NONE; 1997 if (atomic_cmpset_int(&swblk_zone_exhausted, 1998 1, 0)) 1999 printf("swblk zone ok\n"); 2000 break; 2001 } 2002 VM_OBJECT_WUNLOCK(object); 2003 if (uma_zone_exhausted(swblk_zone)) { 2004 if (atomic_cmpset_int(&swblk_zone_exhausted, 2005 0, 1)) 2006 printf("swap blk zone exhausted, " 2007 "increase kern.maxswzone\n"); 2008 vm_pageout_oom(VM_OOM_SWAPZ); 2009 pause("swzonxb", 10); 2010 } else 2011 uma_zwait(swblk_zone); 2012 VM_OBJECT_WLOCK(object); 2013 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2014 rdpi); 2015 if (sb != NULL) 2016 /* 2017 * Somebody swapped out a nearby page, 2018 * allocating swblk at the rdpi index, 2019 * while we dropped the object lock. 2020 */ 2021 goto allocated; 2022 } 2023 for (;;) { 2024 error = SWAP_PCTRIE_INSERT( 2025 &object->un_pager.swp.swp_blks, sb); 2026 if (error == 0) { 2027 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2028 1, 0)) 2029 printf("swpctrie zone ok\n"); 2030 break; 2031 } 2032 VM_OBJECT_WUNLOCK(object); 2033 if (uma_zone_exhausted(swpctrie_zone)) { 2034 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2035 0, 1)) 2036 printf("swap pctrie zone exhausted, " 2037 "increase kern.maxswzone\n"); 2038 vm_pageout_oom(VM_OOM_SWAPZ); 2039 pause("swzonxp", 10); 2040 } else 2041 uma_zwait(swpctrie_zone); 2042 VM_OBJECT_WLOCK(object); 2043 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2044 rdpi); 2045 if (sb1 != NULL) { 2046 uma_zfree(swblk_zone, sb); 2047 sb = sb1; 2048 goto allocated; 2049 } 2050 } 2051 } 2052 allocated: 2053 MPASS(sb->p == rdpi); 2054 2055 modpi = pindex % SWAP_META_PAGES; 2056 /* Return prior contents of metadata. */ 2057 prev_swapblk = sb->d[modpi]; 2058 /* Enter block into metadata. */ 2059 sb->d[modpi] = swapblk; 2060 2061 /* 2062 * Free the swblk if we end up with the empty page run. 2063 */ 2064 if (swapblk == SWAPBLK_NONE) 2065 swp_pager_free_empty_swblk(object, sb); 2066 return (prev_swapblk); 2067 } 2068 2069 /* 2070 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2071 * metadata, or transfer it into dstobject. 2072 * 2073 * This routine will free swap metadata structures as they are cleaned 2074 * out. 2075 */ 2076 static void 2077 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2078 vm_pindex_t pindex, vm_pindex_t count) 2079 { 2080 struct swblk *sb; 2081 daddr_t n_free, s_free; 2082 vm_pindex_t offset, last; 2083 int i, limit, start; 2084 2085 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2086 if (srcobject->type != OBJT_SWAP || count == 0) 2087 return; 2088 2089 swp_pager_init_freerange(&s_free, &n_free); 2090 offset = pindex; 2091 last = pindex + count; 2092 for (;;) { 2093 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2094 rounddown(pindex, SWAP_META_PAGES)); 2095 if (sb == NULL || sb->p >= last) 2096 break; 2097 start = pindex > sb->p ? pindex - sb->p : 0; 2098 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2099 SWAP_META_PAGES; 2100 for (i = start; i < limit; i++) { 2101 if (sb->d[i] == SWAPBLK_NONE) 2102 continue; 2103 if (dstobject == NULL || 2104 !swp_pager_xfer_source(srcobject, dstobject, 2105 sb->p + i - offset, sb->d[i])) { 2106 swp_pager_update_freerange(&s_free, &n_free, 2107 sb->d[i]); 2108 } 2109 sb->d[i] = SWAPBLK_NONE; 2110 } 2111 pindex = sb->p + SWAP_META_PAGES; 2112 if (swp_pager_swblk_empty(sb, 0, start) && 2113 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2114 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2115 sb->p); 2116 uma_zfree(swblk_zone, sb); 2117 } 2118 } 2119 swp_pager_freeswapspace(s_free, n_free); 2120 } 2121 2122 /* 2123 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2124 * 2125 * The requested range of blocks is freed, with any associated swap 2126 * returned to the swap bitmap. 2127 * 2128 * This routine will free swap metadata structures as they are cleaned 2129 * out. This routine does *NOT* operate on swap metadata associated 2130 * with resident pages. 2131 */ 2132 static void 2133 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2134 { 2135 swp_pager_meta_transfer(object, NULL, pindex, count); 2136 } 2137 2138 /* 2139 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2140 * 2141 * This routine locates and destroys all swap metadata associated with 2142 * an object. 2143 */ 2144 static void 2145 swp_pager_meta_free_all(vm_object_t object) 2146 { 2147 struct swblk *sb; 2148 daddr_t n_free, s_free; 2149 vm_pindex_t pindex; 2150 int i; 2151 2152 VM_OBJECT_ASSERT_WLOCKED(object); 2153 if (object->type != OBJT_SWAP) 2154 return; 2155 2156 swp_pager_init_freerange(&s_free, &n_free); 2157 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2158 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2159 pindex = sb->p + SWAP_META_PAGES; 2160 for (i = 0; i < SWAP_META_PAGES; i++) { 2161 if (sb->d[i] == SWAPBLK_NONE) 2162 continue; 2163 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2164 } 2165 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2166 uma_zfree(swblk_zone, sb); 2167 } 2168 swp_pager_freeswapspace(s_free, n_free); 2169 } 2170 2171 /* 2172 * SWP_PAGER_METACTL() - misc control of swap meta data. 2173 * 2174 * This routine is capable of looking up, or removing swapblk 2175 * assignments in the swap meta data. It returns the swapblk being 2176 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2177 * 2178 * When acting on a busy resident page and paging is in progress, we 2179 * have to wait until paging is complete but otherwise can act on the 2180 * busy page. 2181 */ 2182 static daddr_t 2183 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2184 { 2185 struct swblk *sb; 2186 2187 VM_OBJECT_ASSERT_LOCKED(object); 2188 2189 /* 2190 * The meta data only exists if the object is OBJT_SWAP 2191 * and even then might not be allocated yet. 2192 */ 2193 KASSERT(object->type == OBJT_SWAP, 2194 ("Lookup object not swappable")); 2195 2196 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2197 rounddown(pindex, SWAP_META_PAGES)); 2198 if (sb == NULL) 2199 return (SWAPBLK_NONE); 2200 return (sb->d[pindex % SWAP_META_PAGES]); 2201 } 2202 2203 /* 2204 * Returns the least page index which is greater than or equal to the 2205 * parameter pindex and for which there is a swap block allocated. 2206 * Returns object's size if the object's type is not swap or if there 2207 * are no allocated swap blocks for the object after the requested 2208 * pindex. 2209 */ 2210 vm_pindex_t 2211 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2212 { 2213 struct swblk *sb; 2214 int i; 2215 2216 VM_OBJECT_ASSERT_LOCKED(object); 2217 if (object->type != OBJT_SWAP) 2218 return (object->size); 2219 2220 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2221 rounddown(pindex, SWAP_META_PAGES)); 2222 if (sb == NULL) 2223 return (object->size); 2224 if (sb->p < pindex) { 2225 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2226 if (sb->d[i] != SWAPBLK_NONE) 2227 return (sb->p + i); 2228 } 2229 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2230 roundup(pindex, SWAP_META_PAGES)); 2231 if (sb == NULL) 2232 return (object->size); 2233 } 2234 for (i = 0; i < SWAP_META_PAGES; i++) { 2235 if (sb->d[i] != SWAPBLK_NONE) 2236 return (sb->p + i); 2237 } 2238 2239 /* 2240 * We get here if a swblk is present in the trie but it 2241 * doesn't map any blocks. 2242 */ 2243 MPASS(0); 2244 return (object->size); 2245 } 2246 2247 /* 2248 * System call swapon(name) enables swapping on device name, 2249 * which must be in the swdevsw. Return EBUSY 2250 * if already swapping on this device. 2251 */ 2252 #ifndef _SYS_SYSPROTO_H_ 2253 struct swapon_args { 2254 char *name; 2255 }; 2256 #endif 2257 2258 /* 2259 * MPSAFE 2260 */ 2261 /* ARGSUSED */ 2262 int 2263 sys_swapon(struct thread *td, struct swapon_args *uap) 2264 { 2265 struct vattr attr; 2266 struct vnode *vp; 2267 struct nameidata nd; 2268 int error; 2269 2270 error = priv_check(td, PRIV_SWAPON); 2271 if (error) 2272 return (error); 2273 2274 sx_xlock(&swdev_syscall_lock); 2275 2276 /* 2277 * Swap metadata may not fit in the KVM if we have physical 2278 * memory of >1GB. 2279 */ 2280 if (swblk_zone == NULL) { 2281 error = ENOMEM; 2282 goto done; 2283 } 2284 2285 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2286 uap->name, td); 2287 error = namei(&nd); 2288 if (error) 2289 goto done; 2290 2291 NDFREE(&nd, NDF_ONLY_PNBUF); 2292 vp = nd.ni_vp; 2293 2294 if (vn_isdisk(vp, &error)) { 2295 error = swapongeom(vp); 2296 } else if (vp->v_type == VREG && 2297 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2298 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2299 /* 2300 * Allow direct swapping to NFS regular files in the same 2301 * way that nfs_mountroot() sets up diskless swapping. 2302 */ 2303 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2304 } 2305 2306 if (error) 2307 vrele(vp); 2308 done: 2309 sx_xunlock(&swdev_syscall_lock); 2310 return (error); 2311 } 2312 2313 /* 2314 * Check that the total amount of swap currently configured does not 2315 * exceed half the theoretical maximum. If it does, print a warning 2316 * message. 2317 */ 2318 static void 2319 swapon_check_swzone(void) 2320 { 2321 2322 /* recommend using no more than half that amount */ 2323 if (swap_total > swap_maxpages / 2) { 2324 printf("warning: total configured swap (%lu pages) " 2325 "exceeds maximum recommended amount (%lu pages).\n", 2326 swap_total, swap_maxpages / 2); 2327 printf("warning: increase kern.maxswzone " 2328 "or reduce amount of swap.\n"); 2329 } 2330 } 2331 2332 static void 2333 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2334 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2335 { 2336 struct swdevt *sp, *tsp; 2337 daddr_t dvbase; 2338 u_long mblocks; 2339 2340 /* 2341 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2342 * First chop nblks off to page-align it, then convert. 2343 * 2344 * sw->sw_nblks is in page-sized chunks now too. 2345 */ 2346 nblks &= ~(ctodb(1) - 1); 2347 nblks = dbtoc(nblks); 2348 2349 /* 2350 * If we go beyond this, we get overflows in the radix 2351 * tree bitmap code. 2352 */ 2353 mblocks = 0x40000000 / BLIST_META_RADIX; 2354 if (nblks > mblocks) { 2355 printf( 2356 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2357 mblocks / 1024 / 1024 * PAGE_SIZE); 2358 nblks = mblocks; 2359 } 2360 2361 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2362 sp->sw_vp = vp; 2363 sp->sw_id = id; 2364 sp->sw_dev = dev; 2365 sp->sw_nblks = nblks; 2366 sp->sw_used = 0; 2367 sp->sw_strategy = strategy; 2368 sp->sw_close = close; 2369 sp->sw_flags = flags; 2370 2371 sp->sw_blist = blist_create(nblks, M_WAITOK); 2372 /* 2373 * Do not free the first blocks in order to avoid overwriting 2374 * any bsd label at the front of the partition 2375 */ 2376 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2377 nblks - howmany(BBSIZE, PAGE_SIZE)); 2378 2379 dvbase = 0; 2380 mtx_lock(&sw_dev_mtx); 2381 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2382 if (tsp->sw_end >= dvbase) { 2383 /* 2384 * We put one uncovered page between the devices 2385 * in order to definitively prevent any cross-device 2386 * I/O requests 2387 */ 2388 dvbase = tsp->sw_end + 1; 2389 } 2390 } 2391 sp->sw_first = dvbase; 2392 sp->sw_end = dvbase + nblks; 2393 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2394 nswapdev++; 2395 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2396 swap_total += nblks; 2397 swapon_check_swzone(); 2398 swp_sizecheck(); 2399 mtx_unlock(&sw_dev_mtx); 2400 EVENTHANDLER_INVOKE(swapon, sp); 2401 } 2402 2403 /* 2404 * SYSCALL: swapoff(devname) 2405 * 2406 * Disable swapping on the given device. 2407 * 2408 * XXX: Badly designed system call: it should use a device index 2409 * rather than filename as specification. We keep sw_vp around 2410 * only to make this work. 2411 */ 2412 #ifndef _SYS_SYSPROTO_H_ 2413 struct swapoff_args { 2414 char *name; 2415 }; 2416 #endif 2417 2418 /* 2419 * MPSAFE 2420 */ 2421 /* ARGSUSED */ 2422 int 2423 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2424 { 2425 struct vnode *vp; 2426 struct nameidata nd; 2427 struct swdevt *sp; 2428 int error; 2429 2430 error = priv_check(td, PRIV_SWAPOFF); 2431 if (error) 2432 return (error); 2433 2434 sx_xlock(&swdev_syscall_lock); 2435 2436 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2437 td); 2438 error = namei(&nd); 2439 if (error) 2440 goto done; 2441 NDFREE(&nd, NDF_ONLY_PNBUF); 2442 vp = nd.ni_vp; 2443 2444 mtx_lock(&sw_dev_mtx); 2445 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2446 if (sp->sw_vp == vp) 2447 break; 2448 } 2449 mtx_unlock(&sw_dev_mtx); 2450 if (sp == NULL) { 2451 error = EINVAL; 2452 goto done; 2453 } 2454 error = swapoff_one(sp, td->td_ucred); 2455 done: 2456 sx_xunlock(&swdev_syscall_lock); 2457 return (error); 2458 } 2459 2460 static int 2461 swapoff_one(struct swdevt *sp, struct ucred *cred) 2462 { 2463 u_long nblks; 2464 #ifdef MAC 2465 int error; 2466 #endif 2467 2468 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2469 #ifdef MAC 2470 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2471 error = mac_system_check_swapoff(cred, sp->sw_vp); 2472 (void) VOP_UNLOCK(sp->sw_vp); 2473 if (error != 0) 2474 return (error); 2475 #endif 2476 nblks = sp->sw_nblks; 2477 2478 /* 2479 * We can turn off this swap device safely only if the 2480 * available virtual memory in the system will fit the amount 2481 * of data we will have to page back in, plus an epsilon so 2482 * the system doesn't become critically low on swap space. 2483 */ 2484 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2485 return (ENOMEM); 2486 2487 /* 2488 * Prevent further allocations on this device. 2489 */ 2490 mtx_lock(&sw_dev_mtx); 2491 sp->sw_flags |= SW_CLOSING; 2492 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2493 swap_total -= nblks; 2494 mtx_unlock(&sw_dev_mtx); 2495 2496 /* 2497 * Page in the contents of the device and close it. 2498 */ 2499 swap_pager_swapoff(sp); 2500 2501 sp->sw_close(curthread, sp); 2502 mtx_lock(&sw_dev_mtx); 2503 sp->sw_id = NULL; 2504 TAILQ_REMOVE(&swtailq, sp, sw_list); 2505 nswapdev--; 2506 if (nswapdev == 0) { 2507 swap_pager_full = 2; 2508 swap_pager_almost_full = 1; 2509 } 2510 if (swdevhd == sp) 2511 swdevhd = NULL; 2512 mtx_unlock(&sw_dev_mtx); 2513 blist_destroy(sp->sw_blist); 2514 free(sp, M_VMPGDATA); 2515 return (0); 2516 } 2517 2518 void 2519 swapoff_all(void) 2520 { 2521 struct swdevt *sp, *spt; 2522 const char *devname; 2523 int error; 2524 2525 sx_xlock(&swdev_syscall_lock); 2526 2527 mtx_lock(&sw_dev_mtx); 2528 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2529 mtx_unlock(&sw_dev_mtx); 2530 if (vn_isdisk(sp->sw_vp, NULL)) 2531 devname = devtoname(sp->sw_vp->v_rdev); 2532 else 2533 devname = "[file]"; 2534 error = swapoff_one(sp, thread0.td_ucred); 2535 if (error != 0) { 2536 printf("Cannot remove swap device %s (error=%d), " 2537 "skipping.\n", devname, error); 2538 } else if (bootverbose) { 2539 printf("Swap device %s removed.\n", devname); 2540 } 2541 mtx_lock(&sw_dev_mtx); 2542 } 2543 mtx_unlock(&sw_dev_mtx); 2544 2545 sx_xunlock(&swdev_syscall_lock); 2546 } 2547 2548 void 2549 swap_pager_status(int *total, int *used) 2550 { 2551 struct swdevt *sp; 2552 2553 *total = 0; 2554 *used = 0; 2555 mtx_lock(&sw_dev_mtx); 2556 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2557 *total += sp->sw_nblks; 2558 *used += sp->sw_used; 2559 } 2560 mtx_unlock(&sw_dev_mtx); 2561 } 2562 2563 int 2564 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2565 { 2566 struct swdevt *sp; 2567 const char *tmp_devname; 2568 int error, n; 2569 2570 n = 0; 2571 error = ENOENT; 2572 mtx_lock(&sw_dev_mtx); 2573 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2574 if (n != name) { 2575 n++; 2576 continue; 2577 } 2578 xs->xsw_version = XSWDEV_VERSION; 2579 xs->xsw_dev = sp->sw_dev; 2580 xs->xsw_flags = sp->sw_flags; 2581 xs->xsw_nblks = sp->sw_nblks; 2582 xs->xsw_used = sp->sw_used; 2583 if (devname != NULL) { 2584 if (vn_isdisk(sp->sw_vp, NULL)) 2585 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2586 else 2587 tmp_devname = "[file]"; 2588 strncpy(devname, tmp_devname, len); 2589 } 2590 error = 0; 2591 break; 2592 } 2593 mtx_unlock(&sw_dev_mtx); 2594 return (error); 2595 } 2596 2597 #if defined(COMPAT_FREEBSD11) 2598 #define XSWDEV_VERSION_11 1 2599 struct xswdev11 { 2600 u_int xsw_version; 2601 uint32_t xsw_dev; 2602 int xsw_flags; 2603 int xsw_nblks; 2604 int xsw_used; 2605 }; 2606 #endif 2607 2608 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2609 struct xswdev32 { 2610 u_int xsw_version; 2611 u_int xsw_dev1, xsw_dev2; 2612 int xsw_flags; 2613 int xsw_nblks; 2614 int xsw_used; 2615 }; 2616 #endif 2617 2618 static int 2619 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2620 { 2621 struct xswdev xs; 2622 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2623 struct xswdev32 xs32; 2624 #endif 2625 #if defined(COMPAT_FREEBSD11) 2626 struct xswdev11 xs11; 2627 #endif 2628 int error; 2629 2630 if (arg2 != 1) /* name length */ 2631 return (EINVAL); 2632 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2633 if (error != 0) 2634 return (error); 2635 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2636 if (req->oldlen == sizeof(xs32)) { 2637 xs32.xsw_version = XSWDEV_VERSION; 2638 xs32.xsw_dev1 = xs.xsw_dev; 2639 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2640 xs32.xsw_flags = xs.xsw_flags; 2641 xs32.xsw_nblks = xs.xsw_nblks; 2642 xs32.xsw_used = xs.xsw_used; 2643 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2644 return (error); 2645 } 2646 #endif 2647 #if defined(COMPAT_FREEBSD11) 2648 if (req->oldlen == sizeof(xs11)) { 2649 xs11.xsw_version = XSWDEV_VERSION_11; 2650 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2651 xs11.xsw_flags = xs.xsw_flags; 2652 xs11.xsw_nblks = xs.xsw_nblks; 2653 xs11.xsw_used = xs.xsw_used; 2654 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2655 return (error); 2656 } 2657 #endif 2658 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2659 return (error); 2660 } 2661 2662 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2663 "Number of swap devices"); 2664 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2665 sysctl_vm_swap_info, 2666 "Swap statistics by device"); 2667 2668 /* 2669 * Count the approximate swap usage in pages for a vmspace. The 2670 * shadowed or not yet copied on write swap blocks are not accounted. 2671 * The map must be locked. 2672 */ 2673 long 2674 vmspace_swap_count(struct vmspace *vmspace) 2675 { 2676 vm_map_t map; 2677 vm_map_entry_t cur; 2678 vm_object_t object; 2679 struct swblk *sb; 2680 vm_pindex_t e, pi; 2681 long count; 2682 int i; 2683 2684 map = &vmspace->vm_map; 2685 count = 0; 2686 2687 VM_MAP_ENTRY_FOREACH(cur, map) { 2688 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2689 continue; 2690 object = cur->object.vm_object; 2691 if (object == NULL || object->type != OBJT_SWAP) 2692 continue; 2693 VM_OBJECT_RLOCK(object); 2694 if (object->type != OBJT_SWAP) 2695 goto unlock; 2696 pi = OFF_TO_IDX(cur->offset); 2697 e = pi + OFF_TO_IDX(cur->end - cur->start); 2698 for (;; pi = sb->p + SWAP_META_PAGES) { 2699 sb = SWAP_PCTRIE_LOOKUP_GE( 2700 &object->un_pager.swp.swp_blks, pi); 2701 if (sb == NULL || sb->p >= e) 2702 break; 2703 for (i = 0; i < SWAP_META_PAGES; i++) { 2704 if (sb->p + i < e && 2705 sb->d[i] != SWAPBLK_NONE) 2706 count++; 2707 } 2708 } 2709 unlock: 2710 VM_OBJECT_RUNLOCK(object); 2711 } 2712 return (count); 2713 } 2714 2715 /* 2716 * GEOM backend 2717 * 2718 * Swapping onto disk devices. 2719 * 2720 */ 2721 2722 static g_orphan_t swapgeom_orphan; 2723 2724 static struct g_class g_swap_class = { 2725 .name = "SWAP", 2726 .version = G_VERSION, 2727 .orphan = swapgeom_orphan, 2728 }; 2729 2730 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2731 2732 2733 static void 2734 swapgeom_close_ev(void *arg, int flags) 2735 { 2736 struct g_consumer *cp; 2737 2738 cp = arg; 2739 g_access(cp, -1, -1, 0); 2740 g_detach(cp); 2741 g_destroy_consumer(cp); 2742 } 2743 2744 /* 2745 * Add a reference to the g_consumer for an inflight transaction. 2746 */ 2747 static void 2748 swapgeom_acquire(struct g_consumer *cp) 2749 { 2750 2751 mtx_assert(&sw_dev_mtx, MA_OWNED); 2752 cp->index++; 2753 } 2754 2755 /* 2756 * Remove a reference from the g_consumer. Post a close event if all 2757 * references go away, since the function might be called from the 2758 * biodone context. 2759 */ 2760 static void 2761 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2762 { 2763 2764 mtx_assert(&sw_dev_mtx, MA_OWNED); 2765 cp->index--; 2766 if (cp->index == 0) { 2767 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2768 sp->sw_id = NULL; 2769 } 2770 } 2771 2772 static void 2773 swapgeom_done(struct bio *bp2) 2774 { 2775 struct swdevt *sp; 2776 struct buf *bp; 2777 struct g_consumer *cp; 2778 2779 bp = bp2->bio_caller2; 2780 cp = bp2->bio_from; 2781 bp->b_ioflags = bp2->bio_flags; 2782 if (bp2->bio_error) 2783 bp->b_ioflags |= BIO_ERROR; 2784 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2785 bp->b_error = bp2->bio_error; 2786 bp->b_caller1 = NULL; 2787 bufdone(bp); 2788 sp = bp2->bio_caller1; 2789 mtx_lock(&sw_dev_mtx); 2790 swapgeom_release(cp, sp); 2791 mtx_unlock(&sw_dev_mtx); 2792 g_destroy_bio(bp2); 2793 } 2794 2795 static void 2796 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2797 { 2798 struct bio *bio; 2799 struct g_consumer *cp; 2800 2801 mtx_lock(&sw_dev_mtx); 2802 cp = sp->sw_id; 2803 if (cp == NULL) { 2804 mtx_unlock(&sw_dev_mtx); 2805 bp->b_error = ENXIO; 2806 bp->b_ioflags |= BIO_ERROR; 2807 bufdone(bp); 2808 return; 2809 } 2810 swapgeom_acquire(cp); 2811 mtx_unlock(&sw_dev_mtx); 2812 if (bp->b_iocmd == BIO_WRITE) 2813 bio = g_new_bio(); 2814 else 2815 bio = g_alloc_bio(); 2816 if (bio == NULL) { 2817 mtx_lock(&sw_dev_mtx); 2818 swapgeom_release(cp, sp); 2819 mtx_unlock(&sw_dev_mtx); 2820 bp->b_error = ENOMEM; 2821 bp->b_ioflags |= BIO_ERROR; 2822 printf("swap_pager: cannot allocate bio\n"); 2823 bufdone(bp); 2824 return; 2825 } 2826 2827 bp->b_caller1 = bio; 2828 bio->bio_caller1 = sp; 2829 bio->bio_caller2 = bp; 2830 bio->bio_cmd = bp->b_iocmd; 2831 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2832 bio->bio_length = bp->b_bcount; 2833 bio->bio_done = swapgeom_done; 2834 if (!buf_mapped(bp)) { 2835 bio->bio_ma = bp->b_pages; 2836 bio->bio_data = unmapped_buf; 2837 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2838 bio->bio_ma_n = bp->b_npages; 2839 bio->bio_flags |= BIO_UNMAPPED; 2840 } else { 2841 bio->bio_data = bp->b_data; 2842 bio->bio_ma = NULL; 2843 } 2844 g_io_request(bio, cp); 2845 return; 2846 } 2847 2848 static void 2849 swapgeom_orphan(struct g_consumer *cp) 2850 { 2851 struct swdevt *sp; 2852 int destroy; 2853 2854 mtx_lock(&sw_dev_mtx); 2855 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2856 if (sp->sw_id == cp) { 2857 sp->sw_flags |= SW_CLOSING; 2858 break; 2859 } 2860 } 2861 /* 2862 * Drop reference we were created with. Do directly since we're in a 2863 * special context where we don't have to queue the call to 2864 * swapgeom_close_ev(). 2865 */ 2866 cp->index--; 2867 destroy = ((sp != NULL) && (cp->index == 0)); 2868 if (destroy) 2869 sp->sw_id = NULL; 2870 mtx_unlock(&sw_dev_mtx); 2871 if (destroy) 2872 swapgeom_close_ev(cp, 0); 2873 } 2874 2875 static void 2876 swapgeom_close(struct thread *td, struct swdevt *sw) 2877 { 2878 struct g_consumer *cp; 2879 2880 mtx_lock(&sw_dev_mtx); 2881 cp = sw->sw_id; 2882 sw->sw_id = NULL; 2883 mtx_unlock(&sw_dev_mtx); 2884 2885 /* 2886 * swapgeom_close() may be called from the biodone context, 2887 * where we cannot perform topology changes. Delegate the 2888 * work to the events thread. 2889 */ 2890 if (cp != NULL) 2891 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2892 } 2893 2894 static int 2895 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2896 { 2897 struct g_provider *pp; 2898 struct g_consumer *cp; 2899 static struct g_geom *gp; 2900 struct swdevt *sp; 2901 u_long nblks; 2902 int error; 2903 2904 pp = g_dev_getprovider(dev); 2905 if (pp == NULL) 2906 return (ENODEV); 2907 mtx_lock(&sw_dev_mtx); 2908 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2909 cp = sp->sw_id; 2910 if (cp != NULL && cp->provider == pp) { 2911 mtx_unlock(&sw_dev_mtx); 2912 return (EBUSY); 2913 } 2914 } 2915 mtx_unlock(&sw_dev_mtx); 2916 if (gp == NULL) 2917 gp = g_new_geomf(&g_swap_class, "swap"); 2918 cp = g_new_consumer(gp); 2919 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2920 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2921 g_attach(cp, pp); 2922 /* 2923 * XXX: Every time you think you can improve the margin for 2924 * footshooting, somebody depends on the ability to do so: 2925 * savecore(8) wants to write to our swapdev so we cannot 2926 * set an exclusive count :-( 2927 */ 2928 error = g_access(cp, 1, 1, 0); 2929 if (error != 0) { 2930 g_detach(cp); 2931 g_destroy_consumer(cp); 2932 return (error); 2933 } 2934 nblks = pp->mediasize / DEV_BSIZE; 2935 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2936 swapgeom_close, dev2udev(dev), 2937 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2938 return (0); 2939 } 2940 2941 static int 2942 swapongeom(struct vnode *vp) 2943 { 2944 int error; 2945 2946 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2947 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 2948 error = ENOENT; 2949 } else { 2950 g_topology_lock(); 2951 error = swapongeom_locked(vp->v_rdev, vp); 2952 g_topology_unlock(); 2953 } 2954 VOP_UNLOCK(vp); 2955 return (error); 2956 } 2957 2958 /* 2959 * VNODE backend 2960 * 2961 * This is used mainly for network filesystem (read: probably only tested 2962 * with NFS) swapfiles. 2963 * 2964 */ 2965 2966 static void 2967 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2968 { 2969 struct vnode *vp2; 2970 2971 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2972 2973 vp2 = sp->sw_id; 2974 vhold(vp2); 2975 if (bp->b_iocmd == BIO_WRITE) { 2976 if (bp->b_bufobj) 2977 bufobj_wdrop(bp->b_bufobj); 2978 bufobj_wref(&vp2->v_bufobj); 2979 } 2980 if (bp->b_bufobj != &vp2->v_bufobj) 2981 bp->b_bufobj = &vp2->v_bufobj; 2982 bp->b_vp = vp2; 2983 bp->b_iooffset = dbtob(bp->b_blkno); 2984 bstrategy(bp); 2985 return; 2986 } 2987 2988 static void 2989 swapdev_close(struct thread *td, struct swdevt *sp) 2990 { 2991 2992 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2993 vrele(sp->sw_vp); 2994 } 2995 2996 2997 static int 2998 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2999 { 3000 struct swdevt *sp; 3001 int error; 3002 3003 if (nblks == 0) 3004 return (ENXIO); 3005 mtx_lock(&sw_dev_mtx); 3006 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3007 if (sp->sw_id == vp) { 3008 mtx_unlock(&sw_dev_mtx); 3009 return (EBUSY); 3010 } 3011 } 3012 mtx_unlock(&sw_dev_mtx); 3013 3014 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3015 #ifdef MAC 3016 error = mac_system_check_swapon(td->td_ucred, vp); 3017 if (error == 0) 3018 #endif 3019 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3020 (void) VOP_UNLOCK(vp); 3021 if (error) 3022 return (error); 3023 3024 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3025 NODEV, 0); 3026 return (0); 3027 } 3028 3029 static int 3030 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3031 { 3032 int error, new, n; 3033 3034 new = nsw_wcount_async_max; 3035 error = sysctl_handle_int(oidp, &new, 0, req); 3036 if (error != 0 || req->newptr == NULL) 3037 return (error); 3038 3039 if (new > nswbuf / 2 || new < 1) 3040 return (EINVAL); 3041 3042 mtx_lock(&swbuf_mtx); 3043 while (nsw_wcount_async_max != new) { 3044 /* 3045 * Adjust difference. If the current async count is too low, 3046 * we will need to sqeeze our update slowly in. Sleep with a 3047 * higher priority than getpbuf() to finish faster. 3048 */ 3049 n = new - nsw_wcount_async_max; 3050 if (nsw_wcount_async + n >= 0) { 3051 nsw_wcount_async += n; 3052 nsw_wcount_async_max += n; 3053 wakeup(&nsw_wcount_async); 3054 } else { 3055 nsw_wcount_async_max -= nsw_wcount_async; 3056 nsw_wcount_async = 0; 3057 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3058 "swpsysctl", 0); 3059 } 3060 } 3061 mtx_unlock(&swbuf_mtx); 3062 3063 return (0); 3064 } 3065 3066 static void 3067 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3068 vm_offset_t end) 3069 { 3070 3071 VM_OBJECT_WLOCK(object); 3072 KASSERT((object->flags & OBJ_ANON) == 0, 3073 ("Splittable object with writecount")); 3074 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3075 VM_OBJECT_WUNLOCK(object); 3076 } 3077 3078 static void 3079 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3080 vm_offset_t end) 3081 { 3082 3083 VM_OBJECT_WLOCK(object); 3084 KASSERT((object->flags & OBJ_ANON) == 0, 3085 ("Splittable object with writecount")); 3086 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3087 VM_OBJECT_WUNLOCK(object); 3088 } 3089