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 | CTLFLAG_MPSAFE, 0, 160 "VM swap stats"); 161 162 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 163 &swap_reserved, 0, sysctl_page_shift, "A", 164 "Amount of swap storage needed to back all allocated anonymous memory."); 165 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 166 &swap_total, 0, sysctl_page_shift, "A", 167 "Total amount of available swap storage."); 168 169 static int overcommit = 0; 170 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 171 "Configure virtual memory overcommit behavior. See tuning(7) " 172 "for details."); 173 static unsigned long swzone; 174 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 175 "Actual size of swap metadata zone"); 176 static unsigned long swap_maxpages; 177 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 178 "Maximum amount of swap supported"); 179 180 static counter_u64_t swap_free_deferred; 181 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 182 CTLFLAG_RD, &swap_free_deferred, 183 "Number of pages that deferred freeing swap space"); 184 185 static counter_u64_t swap_free_completed; 186 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 187 CTLFLAG_RD, &swap_free_completed, 188 "Number of deferred frees completed"); 189 190 /* bits from overcommit */ 191 #define SWAP_RESERVE_FORCE_ON (1 << 0) 192 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 193 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 194 195 static int 196 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 197 { 198 uint64_t newval; 199 u_long value = *(u_long *)arg1; 200 201 newval = ((uint64_t)value) << PAGE_SHIFT; 202 return (sysctl_handle_64(oidp, &newval, 0, req)); 203 } 204 205 int 206 swap_reserve(vm_ooffset_t incr) 207 { 208 209 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 210 } 211 212 int 213 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 214 { 215 u_long r, s, prev, pincr; 216 int res, error; 217 static int curfail; 218 static struct timeval lastfail; 219 struct uidinfo *uip; 220 221 uip = cred->cr_ruidinfo; 222 223 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 224 (uintmax_t)incr)); 225 226 #ifdef RACCT 227 if (racct_enable) { 228 PROC_LOCK(curproc); 229 error = racct_add(curproc, RACCT_SWAP, incr); 230 PROC_UNLOCK(curproc); 231 if (error != 0) 232 return (0); 233 } 234 #endif 235 236 pincr = atop(incr); 237 res = 0; 238 prev = atomic_fetchadd_long(&swap_reserved, pincr); 239 r = prev + pincr; 240 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 241 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 242 vm_wire_count(); 243 } else 244 s = 0; 245 s += swap_total; 246 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 247 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 248 res = 1; 249 } else { 250 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 251 if (prev < pincr) 252 panic("swap_reserved < incr on overcommit fail"); 253 } 254 if (res) { 255 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 256 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 257 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 258 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 259 res = 0; 260 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 261 if (prev < pincr) 262 panic("uip->ui_vmsize < incr on overcommit fail"); 263 } 264 } 265 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 266 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 267 uip->ui_uid, curproc->p_pid, incr); 268 } 269 270 #ifdef RACCT 271 if (racct_enable && !res) { 272 PROC_LOCK(curproc); 273 racct_sub(curproc, RACCT_SWAP, incr); 274 PROC_UNLOCK(curproc); 275 } 276 #endif 277 278 return (res); 279 } 280 281 void 282 swap_reserve_force(vm_ooffset_t incr) 283 { 284 struct uidinfo *uip; 285 u_long pincr; 286 287 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 288 (uintmax_t)incr)); 289 290 PROC_LOCK(curproc); 291 #ifdef RACCT 292 if (racct_enable) 293 racct_add_force(curproc, RACCT_SWAP, incr); 294 #endif 295 pincr = atop(incr); 296 atomic_add_long(&swap_reserved, pincr); 297 uip = curproc->p_ucred->cr_ruidinfo; 298 atomic_add_long(&uip->ui_vmsize, pincr); 299 PROC_UNLOCK(curproc); 300 } 301 302 void 303 swap_release(vm_ooffset_t decr) 304 { 305 struct ucred *cred; 306 307 PROC_LOCK(curproc); 308 cred = curproc->p_ucred; 309 swap_release_by_cred(decr, cred); 310 PROC_UNLOCK(curproc); 311 } 312 313 void 314 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 315 { 316 u_long prev, pdecr; 317 struct uidinfo *uip; 318 319 uip = cred->cr_ruidinfo; 320 321 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 322 (uintmax_t)decr)); 323 324 pdecr = atop(decr); 325 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 326 if (prev < pdecr) 327 panic("swap_reserved < decr"); 328 329 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 330 if (prev < pdecr) 331 printf("negative vmsize for uid = %d\n", uip->ui_uid); 332 #ifdef RACCT 333 if (racct_enable) 334 racct_sub_cred(cred, RACCT_SWAP, decr); 335 #endif 336 } 337 338 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 339 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 340 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 341 static int nsw_wcount_async; /* limit async write buffers */ 342 static int nsw_wcount_async_max;/* assigned maximum */ 343 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 344 345 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 346 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 347 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 348 "Maximum running async swap ops"); 349 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 350 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 351 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 352 "Swap Fragmentation Info"); 353 354 static struct sx sw_alloc_sx; 355 356 /* 357 * "named" and "unnamed" anon region objects. Try to reduce the overhead 358 * of searching a named list by hashing it just a little. 359 */ 360 361 #define NOBJLISTS 8 362 363 #define NOBJLIST(handle) \ 364 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 365 366 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 367 static uma_zone_t swwbuf_zone; 368 static uma_zone_t swrbuf_zone; 369 static uma_zone_t swblk_zone; 370 static uma_zone_t swpctrie_zone; 371 372 /* 373 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 374 * calls hooked from other parts of the VM system and do not appear here. 375 * (see vm/swap_pager.h). 376 */ 377 static vm_object_t 378 swap_pager_alloc(void *handle, vm_ooffset_t size, 379 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 380 static void swap_pager_dealloc(vm_object_t object); 381 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 382 int *); 383 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 384 int *, pgo_getpages_iodone_t, void *); 385 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 386 static boolean_t 387 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 388 static void swap_pager_init(void); 389 static void swap_pager_unswapped(vm_page_t); 390 static void swap_pager_swapoff(struct swdevt *sp); 391 static void swap_pager_update_writecount(vm_object_t object, 392 vm_offset_t start, vm_offset_t end); 393 static void swap_pager_release_writecount(vm_object_t object, 394 vm_offset_t start, vm_offset_t end); 395 396 struct pagerops swappagerops = { 397 .pgo_init = swap_pager_init, /* early system initialization of pager */ 398 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 399 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 400 .pgo_getpages = swap_pager_getpages, /* pagein */ 401 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 402 .pgo_putpages = swap_pager_putpages, /* pageout */ 403 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 404 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 405 .pgo_update_writecount = swap_pager_update_writecount, 406 .pgo_release_writecount = swap_pager_release_writecount, 407 }; 408 409 /* 410 * swap_*() routines are externally accessible. swp_*() routines are 411 * internal. 412 */ 413 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 414 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 415 416 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 417 "Maximum size of a swap block in pages"); 418 419 static void swp_sizecheck(void); 420 static void swp_pager_async_iodone(struct buf *bp); 421 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 422 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 423 static int swapongeom(struct vnode *); 424 static int swaponvp(struct thread *, struct vnode *, u_long); 425 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 426 427 /* 428 * Swap bitmap functions 429 */ 430 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 431 static daddr_t swp_pager_getswapspace(int *npages); 432 433 /* 434 * Metadata functions 435 */ 436 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 437 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 438 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 439 vm_pindex_t pindex, vm_pindex_t count); 440 static void swp_pager_meta_free_all(vm_object_t); 441 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 442 443 static void 444 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 445 { 446 447 *start = SWAPBLK_NONE; 448 *num = 0; 449 } 450 451 static void 452 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 453 { 454 455 if (*start + *num == addr) { 456 (*num)++; 457 } else { 458 swp_pager_freeswapspace(*start, *num); 459 *start = addr; 460 *num = 1; 461 } 462 } 463 464 static void * 465 swblk_trie_alloc(struct pctrie *ptree) 466 { 467 468 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 469 M_USE_RESERVE : 0))); 470 } 471 472 static void 473 swblk_trie_free(struct pctrie *ptree, void *node) 474 { 475 476 uma_zfree(swpctrie_zone, node); 477 } 478 479 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 480 481 /* 482 * SWP_SIZECHECK() - update swap_pager_full indication 483 * 484 * update the swap_pager_almost_full indication and warn when we are 485 * about to run out of swap space, using lowat/hiwat hysteresis. 486 * 487 * Clear swap_pager_full ( task killing ) indication when lowat is met. 488 * 489 * No restrictions on call 490 * This routine may not block. 491 */ 492 static void 493 swp_sizecheck(void) 494 { 495 496 if (swap_pager_avail < nswap_lowat) { 497 if (swap_pager_almost_full == 0) { 498 printf("swap_pager: out of swap space\n"); 499 swap_pager_almost_full = 1; 500 } 501 } else { 502 swap_pager_full = 0; 503 if (swap_pager_avail > nswap_hiwat) 504 swap_pager_almost_full = 0; 505 } 506 } 507 508 /* 509 * SWAP_PAGER_INIT() - initialize the swap pager! 510 * 511 * Expected to be started from system init. NOTE: This code is run 512 * before much else so be careful what you depend on. Most of the VM 513 * system has yet to be initialized at this point. 514 */ 515 static void 516 swap_pager_init(void) 517 { 518 /* 519 * Initialize object lists 520 */ 521 int i; 522 523 for (i = 0; i < NOBJLISTS; ++i) 524 TAILQ_INIT(&swap_pager_object_list[i]); 525 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 526 sx_init(&sw_alloc_sx, "swspsx"); 527 sx_init(&swdev_syscall_lock, "swsysc"); 528 } 529 530 static void 531 swap_pager_counters(void) 532 { 533 534 swap_free_deferred = counter_u64_alloc(M_WAITOK); 535 swap_free_completed = counter_u64_alloc(M_WAITOK); 536 } 537 SYSINIT(swap_counters, SI_SUB_CPU, SI_ORDER_ANY, swap_pager_counters, NULL); 538 539 /* 540 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 541 * 542 * Expected to be started from pageout process once, prior to entering 543 * its main loop. 544 */ 545 void 546 swap_pager_swap_init(void) 547 { 548 unsigned long n, n2; 549 550 /* 551 * Number of in-transit swap bp operations. Don't 552 * exhaust the pbufs completely. Make sure we 553 * initialize workable values (0 will work for hysteresis 554 * but it isn't very efficient). 555 * 556 * The nsw_cluster_max is constrained by the bp->b_pages[] 557 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 558 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 559 * constrained by the swap device interleave stripe size. 560 * 561 * Currently we hardwire nsw_wcount_async to 4. This limit is 562 * designed to prevent other I/O from having high latencies due to 563 * our pageout I/O. The value 4 works well for one or two active swap 564 * devices but is probably a little low if you have more. Even so, 565 * a higher value would probably generate only a limited improvement 566 * with three or four active swap devices since the system does not 567 * typically have to pageout at extreme bandwidths. We will want 568 * at least 2 per swap devices, and 4 is a pretty good value if you 569 * have one NFS swap device due to the command/ack latency over NFS. 570 * So it all works out pretty well. 571 */ 572 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 573 574 nsw_wcount_async = 4; 575 nsw_wcount_async_max = nsw_wcount_async; 576 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 577 578 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 579 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 580 581 /* 582 * Initialize our zone, taking the user's requested size or 583 * estimating the number we need based on the number of pages 584 * in the system. 585 */ 586 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 587 vm_cnt.v_page_count / 2; 588 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 589 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 590 if (swpctrie_zone == NULL) 591 panic("failed to create swap pctrie zone."); 592 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 593 NULL, NULL, _Alignof(struct swblk) - 1, 0); 594 if (swblk_zone == NULL) 595 panic("failed to create swap blk zone."); 596 n2 = n; 597 do { 598 if (uma_zone_reserve_kva(swblk_zone, n)) 599 break; 600 /* 601 * if the allocation failed, try a zone two thirds the 602 * size of the previous attempt. 603 */ 604 n -= ((n + 2) / 3); 605 } while (n > 0); 606 607 /* 608 * Often uma_zone_reserve_kva() cannot reserve exactly the 609 * requested size. Account for the difference when 610 * calculating swap_maxpages. 611 */ 612 n = uma_zone_get_max(swblk_zone); 613 614 if (n < n2) 615 printf("Swap blk zone entries changed from %lu to %lu.\n", 616 n2, n); 617 /* absolute maximum we can handle assuming 100% efficiency */ 618 swap_maxpages = n * SWAP_META_PAGES; 619 swzone = n * sizeof(struct swblk); 620 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 621 printf("Cannot reserve swap pctrie zone, " 622 "reduce kern.maxswzone.\n"); 623 } 624 625 static vm_object_t 626 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 627 vm_ooffset_t offset) 628 { 629 vm_object_t object; 630 631 if (cred != NULL) { 632 if (!swap_reserve_by_cred(size, cred)) 633 return (NULL); 634 crhold(cred); 635 } 636 637 /* 638 * The un_pager.swp.swp_blks trie is initialized by 639 * vm_object_allocate() to ensure the correct order of 640 * visibility to other threads. 641 */ 642 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 643 PAGE_MASK + size)); 644 645 object->un_pager.swp.writemappings = 0; 646 object->handle = handle; 647 if (cred != NULL) { 648 object->cred = cred; 649 object->charge = size; 650 } 651 return (object); 652 } 653 654 /* 655 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 656 * its metadata structures. 657 * 658 * This routine is called from the mmap and fork code to create a new 659 * OBJT_SWAP object. 660 * 661 * This routine must ensure that no live duplicate is created for 662 * the named object request, which is protected against by 663 * holding the sw_alloc_sx lock in case handle != NULL. 664 */ 665 static vm_object_t 666 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 667 vm_ooffset_t offset, struct ucred *cred) 668 { 669 vm_object_t object; 670 671 if (handle != NULL) { 672 /* 673 * Reference existing named region or allocate new one. There 674 * should not be a race here against swp_pager_meta_build() 675 * as called from vm_page_remove() in regards to the lookup 676 * of the handle. 677 */ 678 sx_xlock(&sw_alloc_sx); 679 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 680 if (object == NULL) { 681 object = swap_pager_alloc_init(handle, cred, size, 682 offset); 683 if (object != NULL) { 684 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 685 object, pager_object_list); 686 } 687 } 688 sx_xunlock(&sw_alloc_sx); 689 } else { 690 object = swap_pager_alloc_init(handle, cred, size, offset); 691 } 692 return (object); 693 } 694 695 /* 696 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 697 * 698 * The swap backing for the object is destroyed. The code is 699 * designed such that we can reinstantiate it later, but this 700 * routine is typically called only when the entire object is 701 * about to be destroyed. 702 * 703 * The object must be locked. 704 */ 705 static void 706 swap_pager_dealloc(vm_object_t object) 707 { 708 709 VM_OBJECT_ASSERT_WLOCKED(object); 710 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 711 712 /* 713 * Remove from list right away so lookups will fail if we block for 714 * pageout completion. 715 */ 716 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 717 VM_OBJECT_WUNLOCK(object); 718 sx_xlock(&sw_alloc_sx); 719 TAILQ_REMOVE(NOBJLIST(object->handle), object, 720 pager_object_list); 721 sx_xunlock(&sw_alloc_sx); 722 VM_OBJECT_WLOCK(object); 723 } 724 725 vm_object_pip_wait(object, "swpdea"); 726 727 /* 728 * Free all remaining metadata. We only bother to free it from 729 * the swap meta data. We do not attempt to free swapblk's still 730 * associated with vm_page_t's for this object. We do not care 731 * if paging is still in progress on some objects. 732 */ 733 swp_pager_meta_free_all(object); 734 object->handle = NULL; 735 object->type = OBJT_DEAD; 736 } 737 738 /************************************************************************ 739 * SWAP PAGER BITMAP ROUTINES * 740 ************************************************************************/ 741 742 /* 743 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 744 * 745 * Allocate swap for up to the requested number of pages. The 746 * starting swap block number (a page index) is returned or 747 * SWAPBLK_NONE if the allocation 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) 758 { 759 daddr_t blk; 760 struct swdevt *sp; 761 int mpages, npages; 762 763 KASSERT(*io_npages >= 1, 764 ("%s: npages not positive", __func__)); 765 blk = SWAPBLK_NONE; 766 mpages = *io_npages; 767 npages = imin(BLIST_MAX_ALLOC, mpages); 768 mtx_lock(&sw_dev_mtx); 769 sp = swdevhd; 770 while (!TAILQ_EMPTY(&swtailq)) { 771 if (sp == NULL) 772 sp = TAILQ_FIRST(&swtailq); 773 if ((sp->sw_flags & SW_CLOSING) == 0) 774 blk = blist_alloc(sp->sw_blist, &npages, mpages); 775 if (blk != SWAPBLK_NONE) 776 break; 777 sp = TAILQ_NEXT(sp, sw_list); 778 if (swdevhd == sp) { 779 if (npages == 1) 780 break; 781 mpages = npages - 1; 782 npages >>= 1; 783 } 784 } 785 if (blk != SWAPBLK_NONE) { 786 *io_npages = npages; 787 blk += sp->sw_first; 788 sp->sw_used += npages; 789 swap_pager_avail -= npages; 790 swp_sizecheck(); 791 swdevhd = TAILQ_NEXT(sp, sw_list); 792 } else { 793 if (swap_pager_full != 2) { 794 printf("swp_pager_getswapspace(%d): failed\n", 795 *io_npages); 796 swap_pager_full = 2; 797 swap_pager_almost_full = 1; 798 } 799 swdevhd = NULL; 800 } 801 mtx_unlock(&sw_dev_mtx); 802 return (blk); 803 } 804 805 static bool 806 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 807 { 808 809 return (blk >= sp->sw_first && blk < sp->sw_end); 810 } 811 812 static void 813 swp_pager_strategy(struct buf *bp) 814 { 815 struct swdevt *sp; 816 817 mtx_lock(&sw_dev_mtx); 818 TAILQ_FOREACH(sp, &swtailq, sw_list) { 819 if (swp_pager_isondev(bp->b_blkno, sp)) { 820 mtx_unlock(&sw_dev_mtx); 821 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 822 unmapped_buf_allowed) { 823 bp->b_data = unmapped_buf; 824 bp->b_offset = 0; 825 } else { 826 pmap_qenter((vm_offset_t)bp->b_data, 827 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 828 } 829 sp->sw_strategy(bp, sp); 830 return; 831 } 832 } 833 panic("Swapdev not found"); 834 } 835 836 837 /* 838 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 839 * 840 * This routine returns the specified swap blocks back to the bitmap. 841 * 842 * This routine may not sleep. 843 */ 844 static void 845 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 846 { 847 struct swdevt *sp; 848 849 if (npages == 0) 850 return; 851 mtx_lock(&sw_dev_mtx); 852 TAILQ_FOREACH(sp, &swtailq, sw_list) { 853 if (swp_pager_isondev(blk, sp)) { 854 sp->sw_used -= npages; 855 /* 856 * If we are attempting to stop swapping on 857 * this device, we don't want to mark any 858 * blocks free lest they be reused. 859 */ 860 if ((sp->sw_flags & SW_CLOSING) == 0) { 861 blist_free(sp->sw_blist, blk - sp->sw_first, 862 npages); 863 swap_pager_avail += npages; 864 swp_sizecheck(); 865 } 866 mtx_unlock(&sw_dev_mtx); 867 return; 868 } 869 } 870 panic("Swapdev not found"); 871 } 872 873 /* 874 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 875 */ 876 static int 877 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 878 { 879 struct sbuf sbuf; 880 struct swdevt *sp; 881 const char *devname; 882 int error; 883 884 error = sysctl_wire_old_buffer(req, 0); 885 if (error != 0) 886 return (error); 887 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 888 mtx_lock(&sw_dev_mtx); 889 TAILQ_FOREACH(sp, &swtailq, sw_list) { 890 if (vn_isdisk(sp->sw_vp, NULL)) 891 devname = devtoname(sp->sw_vp->v_rdev); 892 else 893 devname = "[file]"; 894 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 895 blist_stats(sp->sw_blist, &sbuf); 896 } 897 mtx_unlock(&sw_dev_mtx); 898 error = sbuf_finish(&sbuf); 899 sbuf_delete(&sbuf); 900 return (error); 901 } 902 903 /* 904 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 905 * range within an object. 906 * 907 * This is a globally accessible routine. 908 * 909 * This routine removes swapblk assignments from swap metadata. 910 * 911 * The external callers of this routine typically have already destroyed 912 * or renamed vm_page_t's associated with this range in the object so 913 * we should be ok. 914 * 915 * The object must be locked. 916 */ 917 void 918 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 919 { 920 921 swp_pager_meta_free(object, start, size); 922 } 923 924 /* 925 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 926 * 927 * Assigns swap blocks to the specified range within the object. The 928 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 929 * 930 * Returns 0 on success, -1 on failure. 931 */ 932 int 933 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 934 { 935 daddr_t addr, blk, n_free, s_free; 936 int i, j, n; 937 938 swp_pager_init_freerange(&s_free, &n_free); 939 VM_OBJECT_WLOCK(object); 940 for (i = 0; i < size; i += n) { 941 n = size - i; 942 blk = swp_pager_getswapspace(&n); 943 if (blk == SWAPBLK_NONE) { 944 swp_pager_meta_free(object, start, i); 945 VM_OBJECT_WUNLOCK(object); 946 return (-1); 947 } 948 for (j = 0; j < n; ++j) { 949 addr = swp_pager_meta_build(object, 950 start + i + j, blk + j); 951 if (addr != SWAPBLK_NONE) 952 swp_pager_update_freerange(&s_free, &n_free, 953 addr); 954 } 955 } 956 swp_pager_freeswapspace(s_free, n_free); 957 VM_OBJECT_WUNLOCK(object); 958 return (0); 959 } 960 961 static bool 962 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 963 vm_pindex_t pindex, daddr_t addr) 964 { 965 daddr_t dstaddr; 966 967 KASSERT(srcobject->type == OBJT_SWAP, 968 ("%s: Srcobject not swappable", __func__)); 969 if (dstobject->type == OBJT_SWAP && 970 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 971 /* Caller should destroy the source block. */ 972 return (false); 973 } 974 975 /* 976 * Destination has no swapblk and is not resident, transfer source. 977 * swp_pager_meta_build() can sleep. 978 */ 979 VM_OBJECT_WUNLOCK(srcobject); 980 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 981 KASSERT(dstaddr == SWAPBLK_NONE, 982 ("Unexpected destination swapblk")); 983 VM_OBJECT_WLOCK(srcobject); 984 985 return (true); 986 } 987 988 /* 989 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 990 * and destroy the source. 991 * 992 * Copy any valid swapblks from the source to the destination. In 993 * cases where both the source and destination have a valid swapblk, 994 * we keep the destination's. 995 * 996 * This routine is allowed to sleep. It may sleep allocating metadata 997 * indirectly through swp_pager_meta_build(). 998 * 999 * The source object contains no vm_page_t's (which is just as well) 1000 * 1001 * The source object is of type OBJT_SWAP. 1002 * 1003 * The source and destination objects must be locked. 1004 * Both object locks may temporarily be released. 1005 */ 1006 void 1007 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1008 vm_pindex_t offset, int destroysource) 1009 { 1010 1011 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1012 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1013 1014 /* 1015 * If destroysource is set, we remove the source object from the 1016 * swap_pager internal queue now. 1017 */ 1018 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1019 srcobject->handle != NULL) { 1020 VM_OBJECT_WUNLOCK(srcobject); 1021 VM_OBJECT_WUNLOCK(dstobject); 1022 sx_xlock(&sw_alloc_sx); 1023 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1024 pager_object_list); 1025 sx_xunlock(&sw_alloc_sx); 1026 VM_OBJECT_WLOCK(dstobject); 1027 VM_OBJECT_WLOCK(srcobject); 1028 } 1029 1030 /* 1031 * Transfer source to destination. 1032 */ 1033 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1034 1035 /* 1036 * Free left over swap blocks in source. 1037 * 1038 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1039 * double-remove the object from the swap queues. 1040 */ 1041 if (destroysource) { 1042 swp_pager_meta_free_all(srcobject); 1043 /* 1044 * Reverting the type is not necessary, the caller is going 1045 * to destroy srcobject directly, but I'm doing it here 1046 * for consistency since we've removed the object from its 1047 * queues. 1048 */ 1049 srcobject->type = OBJT_DEFAULT; 1050 } 1051 } 1052 1053 /* 1054 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1055 * the requested page. 1056 * 1057 * We determine whether good backing store exists for the requested 1058 * page and return TRUE if it does, FALSE if it doesn't. 1059 * 1060 * If TRUE, we also try to determine how much valid, contiguous backing 1061 * store exists before and after the requested page. 1062 */ 1063 static boolean_t 1064 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1065 int *after) 1066 { 1067 daddr_t blk, blk0; 1068 int i; 1069 1070 VM_OBJECT_ASSERT_LOCKED(object); 1071 KASSERT(object->type == OBJT_SWAP, 1072 ("%s: object not swappable", __func__)); 1073 1074 /* 1075 * do we have good backing store at the requested index ? 1076 */ 1077 blk0 = swp_pager_meta_lookup(object, pindex); 1078 if (blk0 == SWAPBLK_NONE) { 1079 if (before) 1080 *before = 0; 1081 if (after) 1082 *after = 0; 1083 return (FALSE); 1084 } 1085 1086 /* 1087 * find backwards-looking contiguous good backing store 1088 */ 1089 if (before != NULL) { 1090 for (i = 1; i < SWB_NPAGES; i++) { 1091 if (i > pindex) 1092 break; 1093 blk = swp_pager_meta_lookup(object, pindex - i); 1094 if (blk != blk0 - i) 1095 break; 1096 } 1097 *before = i - 1; 1098 } 1099 1100 /* 1101 * find forward-looking contiguous good backing store 1102 */ 1103 if (after != NULL) { 1104 for (i = 1; i < SWB_NPAGES; i++) { 1105 blk = swp_pager_meta_lookup(object, pindex + i); 1106 if (blk != blk0 + i) 1107 break; 1108 } 1109 *after = i - 1; 1110 } 1111 return (TRUE); 1112 } 1113 1114 /* 1115 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1116 * 1117 * This removes any associated swap backing store, whether valid or 1118 * not, from the page. 1119 * 1120 * This routine is typically called when a page is made dirty, at 1121 * which point any associated swap can be freed. MADV_FREE also 1122 * calls us in a special-case situation 1123 * 1124 * NOTE!!! If the page is clean and the swap was valid, the caller 1125 * should make the page dirty before calling this routine. This routine 1126 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1127 * depends on it. 1128 * 1129 * This routine may not sleep. 1130 * 1131 * The object containing the page may be locked. 1132 */ 1133 static void 1134 swap_pager_unswapped(vm_page_t m) 1135 { 1136 struct swblk *sb; 1137 vm_object_t obj; 1138 1139 /* 1140 * Handle enqueing deferred frees first. If we do not have the 1141 * object lock we wait for the page daemon to clear the space. 1142 */ 1143 obj = m->object; 1144 if (!VM_OBJECT_WOWNED(obj)) { 1145 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1146 /* 1147 * The caller is responsible for synchronization but we 1148 * will harmlessly handle races. This is typically provided 1149 * by only calling unswapped() when a page transitions from 1150 * clean to dirty. 1151 */ 1152 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1153 PGA_SWAP_SPACE) { 1154 vm_page_aflag_set(m, PGA_SWAP_FREE); 1155 counter_u64_add(swap_free_deferred, 1); 1156 } 1157 return; 1158 } 1159 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1160 counter_u64_add(swap_free_completed, 1); 1161 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1162 1163 /* 1164 * The meta data only exists if the object is OBJT_SWAP 1165 * and even then might not be allocated yet. 1166 */ 1167 KASSERT(m->object->type == OBJT_SWAP, 1168 ("Free object not swappable")); 1169 1170 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1171 rounddown(m->pindex, SWAP_META_PAGES)); 1172 if (sb == NULL) 1173 return; 1174 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1175 return; 1176 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1177 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1178 swp_pager_free_empty_swblk(m->object, sb); 1179 } 1180 1181 /* 1182 * swap_pager_getpages() - bring pages in from swap 1183 * 1184 * Attempt to page in the pages in array "ma" of length "count". The 1185 * caller may optionally specify that additional pages preceding and 1186 * succeeding the specified range be paged in. The number of such pages 1187 * is returned in the "rbehind" and "rahead" parameters, and they will 1188 * be in the inactive queue upon return. 1189 * 1190 * The pages in "ma" must be busied and will remain busied upon return. 1191 */ 1192 static int 1193 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1194 int *rbehind, int *rahead) 1195 { 1196 struct buf *bp; 1197 vm_page_t bm, mpred, msucc, p; 1198 vm_pindex_t pindex; 1199 daddr_t blk; 1200 int i, maxahead, maxbehind, reqcount; 1201 1202 VM_OBJECT_ASSERT_WLOCKED(object); 1203 reqcount = count; 1204 1205 KASSERT(object->type == OBJT_SWAP, 1206 ("%s: object not swappable", __func__)); 1207 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1208 VM_OBJECT_WUNLOCK(object); 1209 return (VM_PAGER_FAIL); 1210 } 1211 1212 KASSERT(reqcount - 1 <= maxahead, 1213 ("page count %d extends beyond swap block", reqcount)); 1214 1215 /* 1216 * Do not transfer any pages other than those that are xbusied 1217 * when running during a split or collapse operation. This 1218 * prevents clustering from re-creating pages which are being 1219 * moved into another object. 1220 */ 1221 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1222 maxahead = reqcount - 1; 1223 maxbehind = 0; 1224 } 1225 1226 /* 1227 * Clip the readahead and readbehind ranges to exclude resident pages. 1228 */ 1229 if (rahead != NULL) { 1230 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1231 pindex = ma[reqcount - 1]->pindex; 1232 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1233 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1234 *rahead = msucc->pindex - pindex - 1; 1235 } 1236 if (rbehind != NULL) { 1237 *rbehind = imin(*rbehind, maxbehind); 1238 pindex = ma[0]->pindex; 1239 mpred = TAILQ_PREV(ma[0], pglist, listq); 1240 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1241 *rbehind = pindex - mpred->pindex - 1; 1242 } 1243 1244 bm = ma[0]; 1245 for (i = 0; i < count; i++) 1246 ma[i]->oflags |= VPO_SWAPINPROG; 1247 1248 /* 1249 * Allocate readahead and readbehind pages. 1250 */ 1251 if (rbehind != NULL) { 1252 for (i = 1; i <= *rbehind; i++) { 1253 p = vm_page_alloc(object, ma[0]->pindex - i, 1254 VM_ALLOC_NORMAL); 1255 if (p == NULL) 1256 break; 1257 p->oflags |= VPO_SWAPINPROG; 1258 bm = p; 1259 } 1260 *rbehind = i - 1; 1261 } 1262 if (rahead != NULL) { 1263 for (i = 0; i < *rahead; i++) { 1264 p = vm_page_alloc(object, 1265 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1266 if (p == NULL) 1267 break; 1268 p->oflags |= VPO_SWAPINPROG; 1269 } 1270 *rahead = i; 1271 } 1272 if (rbehind != NULL) 1273 count += *rbehind; 1274 if (rahead != NULL) 1275 count += *rahead; 1276 1277 vm_object_pip_add(object, count); 1278 1279 pindex = bm->pindex; 1280 blk = swp_pager_meta_lookup(object, pindex); 1281 KASSERT(blk != SWAPBLK_NONE, 1282 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1283 1284 VM_OBJECT_WUNLOCK(object); 1285 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1286 /* Pages cannot leave the object while busy. */ 1287 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1288 MPASS(p->pindex == bm->pindex + i); 1289 bp->b_pages[i] = p; 1290 } 1291 1292 bp->b_flags |= B_PAGING; 1293 bp->b_iocmd = BIO_READ; 1294 bp->b_iodone = swp_pager_async_iodone; 1295 bp->b_rcred = crhold(thread0.td_ucred); 1296 bp->b_wcred = crhold(thread0.td_ucred); 1297 bp->b_blkno = blk; 1298 bp->b_bcount = PAGE_SIZE * count; 1299 bp->b_bufsize = PAGE_SIZE * count; 1300 bp->b_npages = count; 1301 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1302 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1303 1304 VM_CNT_INC(v_swapin); 1305 VM_CNT_ADD(v_swappgsin, count); 1306 1307 /* 1308 * perform the I/O. NOTE!!! bp cannot be considered valid after 1309 * this point because we automatically release it on completion. 1310 * Instead, we look at the one page we are interested in which we 1311 * still hold a lock on even through the I/O completion. 1312 * 1313 * The other pages in our ma[] array are also released on completion, 1314 * so we cannot assume they are valid anymore either. 1315 * 1316 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1317 */ 1318 BUF_KERNPROC(bp); 1319 swp_pager_strategy(bp); 1320 1321 /* 1322 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1323 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1324 * is set in the metadata for each page in the request. 1325 */ 1326 VM_OBJECT_WLOCK(object); 1327 /* This could be implemented more efficiently with aflags */ 1328 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1329 ma[0]->oflags |= VPO_SWAPSLEEP; 1330 VM_CNT_INC(v_intrans); 1331 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1332 "swread", hz * 20)) { 1333 printf( 1334 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1335 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1336 } 1337 } 1338 VM_OBJECT_WUNLOCK(object); 1339 1340 /* 1341 * If we had an unrecoverable read error pages will not be valid. 1342 */ 1343 for (i = 0; i < reqcount; i++) 1344 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1345 return (VM_PAGER_ERROR); 1346 1347 return (VM_PAGER_OK); 1348 1349 /* 1350 * A final note: in a low swap situation, we cannot deallocate swap 1351 * and mark a page dirty here because the caller is likely to mark 1352 * the page clean when we return, causing the page to possibly revert 1353 * to all-zero's later. 1354 */ 1355 } 1356 1357 static int 1358 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1359 int *rbehind, int *rahead) 1360 { 1361 1362 VM_OBJECT_WLOCK(object); 1363 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1364 } 1365 1366 /* 1367 * swap_pager_getpages_async(): 1368 * 1369 * Right now this is emulation of asynchronous operation on top of 1370 * swap_pager_getpages(). 1371 */ 1372 static int 1373 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1374 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1375 { 1376 int r, error; 1377 1378 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1379 switch (r) { 1380 case VM_PAGER_OK: 1381 error = 0; 1382 break; 1383 case VM_PAGER_ERROR: 1384 error = EIO; 1385 break; 1386 case VM_PAGER_FAIL: 1387 error = EINVAL; 1388 break; 1389 default: 1390 panic("unhandled swap_pager_getpages() error %d", r); 1391 } 1392 (iodone)(arg, ma, count, error); 1393 1394 return (r); 1395 } 1396 1397 /* 1398 * swap_pager_putpages: 1399 * 1400 * Assign swap (if necessary) and initiate I/O on the specified pages. 1401 * 1402 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1403 * are automatically converted to SWAP objects. 1404 * 1405 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1406 * vm_page reservation system coupled with properly written VFS devices 1407 * should ensure that no low-memory deadlock occurs. This is an area 1408 * which needs work. 1409 * 1410 * The parent has N vm_object_pip_add() references prior to 1411 * calling us and will remove references for rtvals[] that are 1412 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1413 * completion. 1414 * 1415 * The parent has soft-busy'd the pages it passes us and will unbusy 1416 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1417 * We need to unbusy the rest on I/O completion. 1418 */ 1419 static void 1420 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1421 int flags, int *rtvals) 1422 { 1423 struct buf *bp; 1424 daddr_t addr, blk, n_free, s_free; 1425 vm_page_t mreq; 1426 int i, j, n; 1427 bool async; 1428 1429 KASSERT(count == 0 || ma[0]->object == object, 1430 ("%s: object mismatch %p/%p", 1431 __func__, object, ma[0]->object)); 1432 1433 /* 1434 * Step 1 1435 * 1436 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1437 */ 1438 if (object->type != OBJT_SWAP) { 1439 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1440 KASSERT(addr == SWAPBLK_NONE, 1441 ("unexpected object swap block")); 1442 } 1443 VM_OBJECT_WUNLOCK(object); 1444 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1445 swp_pager_init_freerange(&s_free, &n_free); 1446 1447 /* 1448 * Step 2 1449 * 1450 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1451 * The page is left dirty until the pageout operation completes 1452 * successfully. 1453 */ 1454 for (i = 0; i < count; i += n) { 1455 /* Maximum I/O size is limited by maximum swap block size. */ 1456 n = min(count - i, nsw_cluster_max); 1457 1458 if (async) { 1459 mtx_lock(&swbuf_mtx); 1460 while (nsw_wcount_async == 0) 1461 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1462 "swbufa", 0); 1463 nsw_wcount_async--; 1464 mtx_unlock(&swbuf_mtx); 1465 } 1466 1467 /* Get a block of swap of size up to size n. */ 1468 VM_OBJECT_WLOCK(object); 1469 blk = swp_pager_getswapspace(&n); 1470 if (blk == SWAPBLK_NONE) { 1471 VM_OBJECT_WUNLOCK(object); 1472 mtx_lock(&swbuf_mtx); 1473 if (++nsw_wcount_async == 1) 1474 wakeup(&nsw_wcount_async); 1475 mtx_unlock(&swbuf_mtx); 1476 for (j = 0; j < n; ++j) 1477 rtvals[i + j] = VM_PAGER_FAIL; 1478 continue; 1479 } 1480 for (j = 0; j < n; ++j) { 1481 mreq = ma[i + j]; 1482 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1483 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1484 blk + j); 1485 if (addr != SWAPBLK_NONE) 1486 swp_pager_update_freerange(&s_free, &n_free, 1487 addr); 1488 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1489 mreq->oflags |= VPO_SWAPINPROG; 1490 } 1491 VM_OBJECT_WUNLOCK(object); 1492 1493 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1494 if (async) 1495 bp->b_flags = B_ASYNC; 1496 bp->b_flags |= B_PAGING; 1497 bp->b_iocmd = BIO_WRITE; 1498 1499 bp->b_rcred = crhold(thread0.td_ucred); 1500 bp->b_wcred = crhold(thread0.td_ucred); 1501 bp->b_bcount = PAGE_SIZE * n; 1502 bp->b_bufsize = PAGE_SIZE * n; 1503 bp->b_blkno = blk; 1504 for (j = 0; j < n; j++) 1505 bp->b_pages[j] = ma[i + j]; 1506 bp->b_npages = n; 1507 1508 /* 1509 * Must set dirty range for NFS to work. 1510 */ 1511 bp->b_dirtyoff = 0; 1512 bp->b_dirtyend = bp->b_bcount; 1513 1514 VM_CNT_INC(v_swapout); 1515 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1516 1517 /* 1518 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1519 * can call the async completion routine at the end of a 1520 * synchronous I/O operation. Otherwise, our caller would 1521 * perform duplicate unbusy and wakeup operations on the page 1522 * and object, respectively. 1523 */ 1524 for (j = 0; j < n; j++) 1525 rtvals[i + j] = VM_PAGER_PEND; 1526 1527 /* 1528 * asynchronous 1529 * 1530 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1531 */ 1532 if (async) { 1533 bp->b_iodone = swp_pager_async_iodone; 1534 BUF_KERNPROC(bp); 1535 swp_pager_strategy(bp); 1536 continue; 1537 } 1538 1539 /* 1540 * synchronous 1541 * 1542 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1543 */ 1544 bp->b_iodone = bdone; 1545 swp_pager_strategy(bp); 1546 1547 /* 1548 * Wait for the sync I/O to complete. 1549 */ 1550 bwait(bp, PVM, "swwrt"); 1551 1552 /* 1553 * Now that we are through with the bp, we can call the 1554 * normal async completion, which frees everything up. 1555 */ 1556 swp_pager_async_iodone(bp); 1557 } 1558 swp_pager_freeswapspace(s_free, n_free); 1559 VM_OBJECT_WLOCK(object); 1560 } 1561 1562 /* 1563 * swp_pager_async_iodone: 1564 * 1565 * Completion routine for asynchronous reads and writes from/to swap. 1566 * Also called manually by synchronous code to finish up a bp. 1567 * 1568 * This routine may not sleep. 1569 */ 1570 static void 1571 swp_pager_async_iodone(struct buf *bp) 1572 { 1573 int i; 1574 vm_object_t object = NULL; 1575 1576 /* 1577 * Report error - unless we ran out of memory, in which case 1578 * we've already logged it in swapgeom_strategy(). 1579 */ 1580 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1581 printf( 1582 "swap_pager: I/O error - %s failed; blkno %ld," 1583 "size %ld, error %d\n", 1584 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1585 (long)bp->b_blkno, 1586 (long)bp->b_bcount, 1587 bp->b_error 1588 ); 1589 } 1590 1591 /* 1592 * remove the mapping for kernel virtual 1593 */ 1594 if (buf_mapped(bp)) 1595 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1596 else 1597 bp->b_data = bp->b_kvabase; 1598 1599 if (bp->b_npages) { 1600 object = bp->b_pages[0]->object; 1601 VM_OBJECT_WLOCK(object); 1602 } 1603 1604 /* 1605 * cleanup pages. If an error occurs writing to swap, we are in 1606 * very serious trouble. If it happens to be a disk error, though, 1607 * we may be able to recover by reassigning the swap later on. So 1608 * in this case we remove the m->swapblk assignment for the page 1609 * but do not free it in the rlist. The errornous block(s) are thus 1610 * never reallocated as swap. Redirty the page and continue. 1611 */ 1612 for (i = 0; i < bp->b_npages; ++i) { 1613 vm_page_t m = bp->b_pages[i]; 1614 1615 m->oflags &= ~VPO_SWAPINPROG; 1616 if (m->oflags & VPO_SWAPSLEEP) { 1617 m->oflags &= ~VPO_SWAPSLEEP; 1618 wakeup(&object->handle); 1619 } 1620 1621 /* We always have space after I/O, successful or not. */ 1622 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1623 1624 if (bp->b_ioflags & BIO_ERROR) { 1625 /* 1626 * If an error occurs I'd love to throw the swapblk 1627 * away without freeing it back to swapspace, so it 1628 * can never be used again. But I can't from an 1629 * interrupt. 1630 */ 1631 if (bp->b_iocmd == BIO_READ) { 1632 /* 1633 * NOTE: for reads, m->dirty will probably 1634 * be overridden by the original caller of 1635 * getpages so don't play cute tricks here. 1636 */ 1637 vm_page_invalid(m); 1638 } else { 1639 /* 1640 * If a write error occurs, reactivate page 1641 * so it doesn't clog the inactive list, 1642 * then finish the I/O. 1643 */ 1644 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1645 1646 /* PQ_UNSWAPPABLE? */ 1647 vm_page_activate(m); 1648 vm_page_sunbusy(m); 1649 } 1650 } else if (bp->b_iocmd == BIO_READ) { 1651 /* 1652 * NOTE: for reads, m->dirty will probably be 1653 * overridden by the original caller of getpages so 1654 * we cannot set them in order to free the underlying 1655 * swap in a low-swap situation. I don't think we'd 1656 * want to do that anyway, but it was an optimization 1657 * that existed in the old swapper for a time before 1658 * it got ripped out due to precisely this problem. 1659 */ 1660 KASSERT(!pmap_page_is_mapped(m), 1661 ("swp_pager_async_iodone: page %p is mapped", m)); 1662 KASSERT(m->dirty == 0, 1663 ("swp_pager_async_iodone: page %p is dirty", m)); 1664 1665 vm_page_valid(m); 1666 if (i < bp->b_pgbefore || 1667 i >= bp->b_npages - bp->b_pgafter) 1668 vm_page_readahead_finish(m); 1669 } else { 1670 /* 1671 * For write success, clear the dirty 1672 * status, then finish the I/O ( which decrements the 1673 * busy count and possibly wakes waiter's up ). 1674 * A page is only written to swap after a period of 1675 * inactivity. Therefore, we do not expect it to be 1676 * reused. 1677 */ 1678 KASSERT(!pmap_page_is_write_mapped(m), 1679 ("swp_pager_async_iodone: page %p is not write" 1680 " protected", m)); 1681 vm_page_undirty(m); 1682 vm_page_deactivate_noreuse(m); 1683 vm_page_sunbusy(m); 1684 } 1685 } 1686 1687 /* 1688 * adjust pip. NOTE: the original parent may still have its own 1689 * pip refs on the object. 1690 */ 1691 if (object != NULL) { 1692 vm_object_pip_wakeupn(object, bp->b_npages); 1693 VM_OBJECT_WUNLOCK(object); 1694 } 1695 1696 /* 1697 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1698 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1699 * trigger a KASSERT in relpbuf(). 1700 */ 1701 if (bp->b_vp) { 1702 bp->b_vp = NULL; 1703 bp->b_bufobj = NULL; 1704 } 1705 /* 1706 * release the physical I/O buffer 1707 */ 1708 if (bp->b_flags & B_ASYNC) { 1709 mtx_lock(&swbuf_mtx); 1710 if (++nsw_wcount_async == 1) 1711 wakeup(&nsw_wcount_async); 1712 mtx_unlock(&swbuf_mtx); 1713 } 1714 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1715 } 1716 1717 int 1718 swap_pager_nswapdev(void) 1719 { 1720 1721 return (nswapdev); 1722 } 1723 1724 static void 1725 swp_pager_force_dirty(vm_page_t m) 1726 { 1727 1728 vm_page_dirty(m); 1729 swap_pager_unswapped(m); 1730 vm_page_launder(m); 1731 } 1732 1733 /* 1734 * swap_pager_swapoff_object: 1735 * 1736 * Page in all of the pages that have been paged out for an object 1737 * to a swap device. 1738 */ 1739 static void 1740 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1741 { 1742 struct swblk *sb; 1743 vm_page_t m; 1744 vm_pindex_t pi; 1745 daddr_t blk; 1746 int i, nv, rahead, rv; 1747 1748 KASSERT(object->type == OBJT_SWAP, 1749 ("%s: Object not swappable", __func__)); 1750 1751 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1752 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1753 if ((object->flags & OBJ_DEAD) != 0) { 1754 /* 1755 * Make sure that pending writes finish before 1756 * returning. 1757 */ 1758 vm_object_pip_wait(object, "swpoff"); 1759 swp_pager_meta_free_all(object); 1760 break; 1761 } 1762 for (i = 0; i < SWAP_META_PAGES; i++) { 1763 /* 1764 * Count the number of contiguous valid blocks. 1765 */ 1766 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1767 blk = sb->d[i + nv]; 1768 if (!swp_pager_isondev(blk, sp) || 1769 blk == SWAPBLK_NONE) 1770 break; 1771 } 1772 if (nv == 0) 1773 continue; 1774 1775 /* 1776 * Look for a page corresponding to the first 1777 * valid block and ensure that any pending paging 1778 * operations on it are complete. If the page is valid, 1779 * mark it dirty and free the swap block. Try to batch 1780 * this operation since it may cause sp to be freed, 1781 * meaning that we must restart the scan. Avoid busying 1782 * valid pages since we may block forever on kernel 1783 * stack pages. 1784 */ 1785 m = vm_page_lookup(object, sb->p + i); 1786 if (m == NULL) { 1787 m = vm_page_alloc(object, sb->p + i, 1788 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1789 if (m == NULL) 1790 break; 1791 } else { 1792 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1793 m->oflags |= VPO_SWAPSLEEP; 1794 VM_OBJECT_SLEEP(object, &object->handle, 1795 PSWP, "swpoff", 0); 1796 break; 1797 } 1798 if (vm_page_all_valid(m)) { 1799 do { 1800 swp_pager_force_dirty(m); 1801 } while (--nv > 0 && 1802 (m = vm_page_next(m)) != NULL && 1803 vm_page_all_valid(m) && 1804 (m->oflags & VPO_SWAPINPROG) == 0); 1805 break; 1806 } 1807 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1808 break; 1809 } 1810 1811 vm_object_pip_add(object, 1); 1812 rahead = SWAP_META_PAGES; 1813 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1814 &rahead); 1815 if (rv != VM_PAGER_OK) 1816 panic("%s: read from swap failed: %d", 1817 __func__, rv); 1818 vm_object_pip_wakeupn(object, 1); 1819 VM_OBJECT_WLOCK(object); 1820 vm_page_xunbusy(m); 1821 1822 /* 1823 * The object lock was dropped so we must restart the 1824 * scan of this swap block. Pages paged in during this 1825 * iteration will be marked dirty in a future iteration. 1826 */ 1827 break; 1828 } 1829 if (i == SWAP_META_PAGES) 1830 pi = sb->p + SWAP_META_PAGES; 1831 } 1832 } 1833 1834 /* 1835 * swap_pager_swapoff: 1836 * 1837 * Page in all of the pages that have been paged out to the 1838 * given device. The corresponding blocks in the bitmap must be 1839 * marked as allocated and the device must be flagged SW_CLOSING. 1840 * There may be no processes swapped out to the device. 1841 * 1842 * This routine may block. 1843 */ 1844 static void 1845 swap_pager_swapoff(struct swdevt *sp) 1846 { 1847 vm_object_t object; 1848 int retries; 1849 1850 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1851 1852 retries = 0; 1853 full_rescan: 1854 mtx_lock(&vm_object_list_mtx); 1855 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1856 if (object->type != OBJT_SWAP) 1857 continue; 1858 mtx_unlock(&vm_object_list_mtx); 1859 /* Depends on type-stability. */ 1860 VM_OBJECT_WLOCK(object); 1861 1862 /* 1863 * Dead objects are eventually terminated on their own. 1864 */ 1865 if ((object->flags & OBJ_DEAD) != 0) 1866 goto next_obj; 1867 1868 /* 1869 * Sync with fences placed after pctrie 1870 * initialization. We must not access pctrie below 1871 * unless we checked that our object is swap and not 1872 * dead. 1873 */ 1874 atomic_thread_fence_acq(); 1875 if (object->type != OBJT_SWAP) 1876 goto next_obj; 1877 1878 swap_pager_swapoff_object(sp, object); 1879 next_obj: 1880 VM_OBJECT_WUNLOCK(object); 1881 mtx_lock(&vm_object_list_mtx); 1882 } 1883 mtx_unlock(&vm_object_list_mtx); 1884 1885 if (sp->sw_used) { 1886 /* 1887 * Objects may be locked or paging to the device being 1888 * removed, so we will miss their pages and need to 1889 * make another pass. We have marked this device as 1890 * SW_CLOSING, so the activity should finish soon. 1891 */ 1892 retries++; 1893 if (retries > 100) { 1894 panic("swapoff: failed to locate %d swap blocks", 1895 sp->sw_used); 1896 } 1897 pause("swpoff", hz / 20); 1898 goto full_rescan; 1899 } 1900 EVENTHANDLER_INVOKE(swapoff, sp); 1901 } 1902 1903 /************************************************************************ 1904 * SWAP META DATA * 1905 ************************************************************************ 1906 * 1907 * These routines manipulate the swap metadata stored in the 1908 * OBJT_SWAP object. 1909 * 1910 * Swap metadata is implemented with a global hash and not directly 1911 * linked into the object. Instead the object simply contains 1912 * appropriate tracking counters. 1913 */ 1914 1915 /* 1916 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1917 */ 1918 static bool 1919 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1920 { 1921 int i; 1922 1923 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1924 for (i = start; i < limit; i++) { 1925 if (sb->d[i] != SWAPBLK_NONE) 1926 return (false); 1927 } 1928 return (true); 1929 } 1930 1931 /* 1932 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1933 * 1934 * Nothing is done if the block is still in use. 1935 */ 1936 static void 1937 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1938 { 1939 1940 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1941 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1942 uma_zfree(swblk_zone, sb); 1943 } 1944 } 1945 1946 /* 1947 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1948 * 1949 * We first convert the object to a swap object if it is a default 1950 * object. 1951 * 1952 * The specified swapblk is added to the object's swap metadata. If 1953 * the swapblk is not valid, it is freed instead. Any previously 1954 * assigned swapblk is returned. 1955 */ 1956 static daddr_t 1957 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1958 { 1959 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1960 struct swblk *sb, *sb1; 1961 vm_pindex_t modpi, rdpi; 1962 daddr_t prev_swapblk; 1963 int error, i; 1964 1965 VM_OBJECT_ASSERT_WLOCKED(object); 1966 1967 /* 1968 * Convert default object to swap object if necessary 1969 */ 1970 if (object->type != OBJT_SWAP) { 1971 pctrie_init(&object->un_pager.swp.swp_blks); 1972 1973 /* 1974 * Ensure that swap_pager_swapoff()'s iteration over 1975 * object_list does not see a garbage pctrie. 1976 */ 1977 atomic_thread_fence_rel(); 1978 1979 object->type = OBJT_SWAP; 1980 object->un_pager.swp.writemappings = 0; 1981 KASSERT((object->flags & OBJ_ANON) != 0 || 1982 object->handle == NULL, 1983 ("default pager %p with handle %p", 1984 object, object->handle)); 1985 } 1986 1987 rdpi = rounddown(pindex, SWAP_META_PAGES); 1988 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1989 if (sb == NULL) { 1990 if (swapblk == SWAPBLK_NONE) 1991 return (SWAPBLK_NONE); 1992 for (;;) { 1993 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1994 pageproc ? M_USE_RESERVE : 0)); 1995 if (sb != NULL) { 1996 sb->p = rdpi; 1997 for (i = 0; i < SWAP_META_PAGES; i++) 1998 sb->d[i] = SWAPBLK_NONE; 1999 if (atomic_cmpset_int(&swblk_zone_exhausted, 2000 1, 0)) 2001 printf("swblk zone ok\n"); 2002 break; 2003 } 2004 VM_OBJECT_WUNLOCK(object); 2005 if (uma_zone_exhausted(swblk_zone)) { 2006 if (atomic_cmpset_int(&swblk_zone_exhausted, 2007 0, 1)) 2008 printf("swap blk zone exhausted, " 2009 "increase kern.maxswzone\n"); 2010 vm_pageout_oom(VM_OOM_SWAPZ); 2011 pause("swzonxb", 10); 2012 } else 2013 uma_zwait(swblk_zone); 2014 VM_OBJECT_WLOCK(object); 2015 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2016 rdpi); 2017 if (sb != NULL) 2018 /* 2019 * Somebody swapped out a nearby page, 2020 * allocating swblk at the rdpi index, 2021 * while we dropped the object lock. 2022 */ 2023 goto allocated; 2024 } 2025 for (;;) { 2026 error = SWAP_PCTRIE_INSERT( 2027 &object->un_pager.swp.swp_blks, sb); 2028 if (error == 0) { 2029 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2030 1, 0)) 2031 printf("swpctrie zone ok\n"); 2032 break; 2033 } 2034 VM_OBJECT_WUNLOCK(object); 2035 if (uma_zone_exhausted(swpctrie_zone)) { 2036 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2037 0, 1)) 2038 printf("swap pctrie zone exhausted, " 2039 "increase kern.maxswzone\n"); 2040 vm_pageout_oom(VM_OOM_SWAPZ); 2041 pause("swzonxp", 10); 2042 } else 2043 uma_zwait(swpctrie_zone); 2044 VM_OBJECT_WLOCK(object); 2045 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2046 rdpi); 2047 if (sb1 != NULL) { 2048 uma_zfree(swblk_zone, sb); 2049 sb = sb1; 2050 goto allocated; 2051 } 2052 } 2053 } 2054 allocated: 2055 MPASS(sb->p == rdpi); 2056 2057 modpi = pindex % SWAP_META_PAGES; 2058 /* Return prior contents of metadata. */ 2059 prev_swapblk = sb->d[modpi]; 2060 /* Enter block into metadata. */ 2061 sb->d[modpi] = swapblk; 2062 2063 /* 2064 * Free the swblk if we end up with the empty page run. 2065 */ 2066 if (swapblk == SWAPBLK_NONE) 2067 swp_pager_free_empty_swblk(object, sb); 2068 return (prev_swapblk); 2069 } 2070 2071 /* 2072 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2073 * metadata, or transfer it into dstobject. 2074 * 2075 * This routine will free swap metadata structures as they are cleaned 2076 * out. 2077 */ 2078 static void 2079 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2080 vm_pindex_t pindex, vm_pindex_t count) 2081 { 2082 struct swblk *sb; 2083 daddr_t n_free, s_free; 2084 vm_pindex_t offset, last; 2085 int i, limit, start; 2086 2087 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2088 if (srcobject->type != OBJT_SWAP || count == 0) 2089 return; 2090 2091 swp_pager_init_freerange(&s_free, &n_free); 2092 offset = pindex; 2093 last = pindex + count; 2094 for (;;) { 2095 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2096 rounddown(pindex, SWAP_META_PAGES)); 2097 if (sb == NULL || sb->p >= last) 2098 break; 2099 start = pindex > sb->p ? pindex - sb->p : 0; 2100 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2101 SWAP_META_PAGES; 2102 for (i = start; i < limit; i++) { 2103 if (sb->d[i] == SWAPBLK_NONE) 2104 continue; 2105 if (dstobject == NULL || 2106 !swp_pager_xfer_source(srcobject, dstobject, 2107 sb->p + i - offset, sb->d[i])) { 2108 swp_pager_update_freerange(&s_free, &n_free, 2109 sb->d[i]); 2110 } 2111 sb->d[i] = SWAPBLK_NONE; 2112 } 2113 pindex = sb->p + SWAP_META_PAGES; 2114 if (swp_pager_swblk_empty(sb, 0, start) && 2115 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2116 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2117 sb->p); 2118 uma_zfree(swblk_zone, sb); 2119 } 2120 } 2121 swp_pager_freeswapspace(s_free, n_free); 2122 } 2123 2124 /* 2125 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2126 * 2127 * The requested range of blocks is freed, with any associated swap 2128 * returned to the swap bitmap. 2129 * 2130 * This routine will free swap metadata structures as they are cleaned 2131 * out. This routine does *NOT* operate on swap metadata associated 2132 * with resident pages. 2133 */ 2134 static void 2135 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2136 { 2137 swp_pager_meta_transfer(object, NULL, pindex, count); 2138 } 2139 2140 /* 2141 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2142 * 2143 * This routine locates and destroys all swap metadata associated with 2144 * an object. 2145 */ 2146 static void 2147 swp_pager_meta_free_all(vm_object_t object) 2148 { 2149 struct swblk *sb; 2150 daddr_t n_free, s_free; 2151 vm_pindex_t pindex; 2152 int i; 2153 2154 VM_OBJECT_ASSERT_WLOCKED(object); 2155 if (object->type != OBJT_SWAP) 2156 return; 2157 2158 swp_pager_init_freerange(&s_free, &n_free); 2159 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2160 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2161 pindex = sb->p + SWAP_META_PAGES; 2162 for (i = 0; i < SWAP_META_PAGES; i++) { 2163 if (sb->d[i] == SWAPBLK_NONE) 2164 continue; 2165 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2166 } 2167 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2168 uma_zfree(swblk_zone, sb); 2169 } 2170 swp_pager_freeswapspace(s_free, n_free); 2171 } 2172 2173 /* 2174 * SWP_PAGER_METACTL() - misc control of swap meta data. 2175 * 2176 * This routine is capable of looking up, or removing swapblk 2177 * assignments in the swap meta data. It returns the swapblk being 2178 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2179 * 2180 * When acting on a busy resident page and paging is in progress, we 2181 * have to wait until paging is complete but otherwise can act on the 2182 * busy page. 2183 */ 2184 static daddr_t 2185 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2186 { 2187 struct swblk *sb; 2188 2189 VM_OBJECT_ASSERT_LOCKED(object); 2190 2191 /* 2192 * The meta data only exists if the object is OBJT_SWAP 2193 * and even then might not be allocated yet. 2194 */ 2195 KASSERT(object->type == OBJT_SWAP, 2196 ("Lookup object not swappable")); 2197 2198 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2199 rounddown(pindex, SWAP_META_PAGES)); 2200 if (sb == NULL) 2201 return (SWAPBLK_NONE); 2202 return (sb->d[pindex % SWAP_META_PAGES]); 2203 } 2204 2205 /* 2206 * Returns the least page index which is greater than or equal to the 2207 * parameter pindex and for which there is a swap block allocated. 2208 * Returns object's size if the object's type is not swap or if there 2209 * are no allocated swap blocks for the object after the requested 2210 * pindex. 2211 */ 2212 vm_pindex_t 2213 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2214 { 2215 struct swblk *sb; 2216 int i; 2217 2218 VM_OBJECT_ASSERT_LOCKED(object); 2219 if (object->type != OBJT_SWAP) 2220 return (object->size); 2221 2222 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2223 rounddown(pindex, SWAP_META_PAGES)); 2224 if (sb == NULL) 2225 return (object->size); 2226 if (sb->p < pindex) { 2227 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2228 if (sb->d[i] != SWAPBLK_NONE) 2229 return (sb->p + i); 2230 } 2231 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2232 roundup(pindex, SWAP_META_PAGES)); 2233 if (sb == NULL) 2234 return (object->size); 2235 } 2236 for (i = 0; i < SWAP_META_PAGES; i++) { 2237 if (sb->d[i] != SWAPBLK_NONE) 2238 return (sb->p + i); 2239 } 2240 2241 /* 2242 * We get here if a swblk is present in the trie but it 2243 * doesn't map any blocks. 2244 */ 2245 MPASS(0); 2246 return (object->size); 2247 } 2248 2249 /* 2250 * System call swapon(name) enables swapping on device name, 2251 * which must be in the swdevsw. Return EBUSY 2252 * if already swapping on this device. 2253 */ 2254 #ifndef _SYS_SYSPROTO_H_ 2255 struct swapon_args { 2256 char *name; 2257 }; 2258 #endif 2259 2260 /* 2261 * MPSAFE 2262 */ 2263 /* ARGSUSED */ 2264 int 2265 sys_swapon(struct thread *td, struct swapon_args *uap) 2266 { 2267 struct vattr attr; 2268 struct vnode *vp; 2269 struct nameidata nd; 2270 int error; 2271 2272 error = priv_check(td, PRIV_SWAPON); 2273 if (error) 2274 return (error); 2275 2276 sx_xlock(&swdev_syscall_lock); 2277 2278 /* 2279 * Swap metadata may not fit in the KVM if we have physical 2280 * memory of >1GB. 2281 */ 2282 if (swblk_zone == NULL) { 2283 error = ENOMEM; 2284 goto done; 2285 } 2286 2287 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2288 uap->name, td); 2289 error = namei(&nd); 2290 if (error) 2291 goto done; 2292 2293 NDFREE(&nd, NDF_ONLY_PNBUF); 2294 vp = nd.ni_vp; 2295 2296 if (vn_isdisk(vp, &error)) { 2297 error = swapongeom(vp); 2298 } else if (vp->v_type == VREG && 2299 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2300 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2301 /* 2302 * Allow direct swapping to NFS regular files in the same 2303 * way that nfs_mountroot() sets up diskless swapping. 2304 */ 2305 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2306 } 2307 2308 if (error) 2309 vrele(vp); 2310 done: 2311 sx_xunlock(&swdev_syscall_lock); 2312 return (error); 2313 } 2314 2315 /* 2316 * Check that the total amount of swap currently configured does not 2317 * exceed half the theoretical maximum. If it does, print a warning 2318 * message. 2319 */ 2320 static void 2321 swapon_check_swzone(void) 2322 { 2323 2324 /* recommend using no more than half that amount */ 2325 if (swap_total > swap_maxpages / 2) { 2326 printf("warning: total configured swap (%lu pages) " 2327 "exceeds maximum recommended amount (%lu pages).\n", 2328 swap_total, swap_maxpages / 2); 2329 printf("warning: increase kern.maxswzone " 2330 "or reduce amount of swap.\n"); 2331 } 2332 } 2333 2334 static void 2335 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2336 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2337 { 2338 struct swdevt *sp, *tsp; 2339 daddr_t dvbase; 2340 u_long mblocks; 2341 2342 /* 2343 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2344 * First chop nblks off to page-align it, then convert. 2345 * 2346 * sw->sw_nblks is in page-sized chunks now too. 2347 */ 2348 nblks &= ~(ctodb(1) - 1); 2349 nblks = dbtoc(nblks); 2350 2351 /* 2352 * If we go beyond this, we get overflows in the radix 2353 * tree bitmap code. 2354 */ 2355 mblocks = 0x40000000 / BLIST_META_RADIX; 2356 if (nblks > mblocks) { 2357 printf( 2358 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2359 mblocks / 1024 / 1024 * PAGE_SIZE); 2360 nblks = mblocks; 2361 } 2362 2363 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2364 sp->sw_vp = vp; 2365 sp->sw_id = id; 2366 sp->sw_dev = dev; 2367 sp->sw_nblks = nblks; 2368 sp->sw_used = 0; 2369 sp->sw_strategy = strategy; 2370 sp->sw_close = close; 2371 sp->sw_flags = flags; 2372 2373 sp->sw_blist = blist_create(nblks, M_WAITOK); 2374 /* 2375 * Do not free the first blocks in order to avoid overwriting 2376 * any bsd label at the front of the partition 2377 */ 2378 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2379 nblks - howmany(BBSIZE, PAGE_SIZE)); 2380 2381 dvbase = 0; 2382 mtx_lock(&sw_dev_mtx); 2383 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2384 if (tsp->sw_end >= dvbase) { 2385 /* 2386 * We put one uncovered page between the devices 2387 * in order to definitively prevent any cross-device 2388 * I/O requests 2389 */ 2390 dvbase = tsp->sw_end + 1; 2391 } 2392 } 2393 sp->sw_first = dvbase; 2394 sp->sw_end = dvbase + nblks; 2395 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2396 nswapdev++; 2397 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2398 swap_total += nblks; 2399 swapon_check_swzone(); 2400 swp_sizecheck(); 2401 mtx_unlock(&sw_dev_mtx); 2402 EVENTHANDLER_INVOKE(swapon, sp); 2403 } 2404 2405 /* 2406 * SYSCALL: swapoff(devname) 2407 * 2408 * Disable swapping on the given device. 2409 * 2410 * XXX: Badly designed system call: it should use a device index 2411 * rather than filename as specification. We keep sw_vp around 2412 * only to make this work. 2413 */ 2414 #ifndef _SYS_SYSPROTO_H_ 2415 struct swapoff_args { 2416 char *name; 2417 }; 2418 #endif 2419 2420 /* 2421 * MPSAFE 2422 */ 2423 /* ARGSUSED */ 2424 int 2425 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2426 { 2427 struct vnode *vp; 2428 struct nameidata nd; 2429 struct swdevt *sp; 2430 int error; 2431 2432 error = priv_check(td, PRIV_SWAPOFF); 2433 if (error) 2434 return (error); 2435 2436 sx_xlock(&swdev_syscall_lock); 2437 2438 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2439 td); 2440 error = namei(&nd); 2441 if (error) 2442 goto done; 2443 NDFREE(&nd, NDF_ONLY_PNBUF); 2444 vp = nd.ni_vp; 2445 2446 mtx_lock(&sw_dev_mtx); 2447 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2448 if (sp->sw_vp == vp) 2449 break; 2450 } 2451 mtx_unlock(&sw_dev_mtx); 2452 if (sp == NULL) { 2453 error = EINVAL; 2454 goto done; 2455 } 2456 error = swapoff_one(sp, td->td_ucred); 2457 done: 2458 sx_xunlock(&swdev_syscall_lock); 2459 return (error); 2460 } 2461 2462 static int 2463 swapoff_one(struct swdevt *sp, struct ucred *cred) 2464 { 2465 u_long nblks; 2466 #ifdef MAC 2467 int error; 2468 #endif 2469 2470 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2471 #ifdef MAC 2472 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2473 error = mac_system_check_swapoff(cred, sp->sw_vp); 2474 (void) VOP_UNLOCK(sp->sw_vp); 2475 if (error != 0) 2476 return (error); 2477 #endif 2478 nblks = sp->sw_nblks; 2479 2480 /* 2481 * We can turn off this swap device safely only if the 2482 * available virtual memory in the system will fit the amount 2483 * of data we will have to page back in, plus an epsilon so 2484 * the system doesn't become critically low on swap space. 2485 */ 2486 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2487 return (ENOMEM); 2488 2489 /* 2490 * Prevent further allocations on this device. 2491 */ 2492 mtx_lock(&sw_dev_mtx); 2493 sp->sw_flags |= SW_CLOSING; 2494 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2495 swap_total -= nblks; 2496 mtx_unlock(&sw_dev_mtx); 2497 2498 /* 2499 * Page in the contents of the device and close it. 2500 */ 2501 swap_pager_swapoff(sp); 2502 2503 sp->sw_close(curthread, sp); 2504 mtx_lock(&sw_dev_mtx); 2505 sp->sw_id = NULL; 2506 TAILQ_REMOVE(&swtailq, sp, sw_list); 2507 nswapdev--; 2508 if (nswapdev == 0) { 2509 swap_pager_full = 2; 2510 swap_pager_almost_full = 1; 2511 } 2512 if (swdevhd == sp) 2513 swdevhd = NULL; 2514 mtx_unlock(&sw_dev_mtx); 2515 blist_destroy(sp->sw_blist); 2516 free(sp, M_VMPGDATA); 2517 return (0); 2518 } 2519 2520 void 2521 swapoff_all(void) 2522 { 2523 struct swdevt *sp, *spt; 2524 const char *devname; 2525 int error; 2526 2527 sx_xlock(&swdev_syscall_lock); 2528 2529 mtx_lock(&sw_dev_mtx); 2530 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2531 mtx_unlock(&sw_dev_mtx); 2532 if (vn_isdisk(sp->sw_vp, NULL)) 2533 devname = devtoname(sp->sw_vp->v_rdev); 2534 else 2535 devname = "[file]"; 2536 error = swapoff_one(sp, thread0.td_ucred); 2537 if (error != 0) { 2538 printf("Cannot remove swap device %s (error=%d), " 2539 "skipping.\n", devname, error); 2540 } else if (bootverbose) { 2541 printf("Swap device %s removed.\n", devname); 2542 } 2543 mtx_lock(&sw_dev_mtx); 2544 } 2545 mtx_unlock(&sw_dev_mtx); 2546 2547 sx_xunlock(&swdev_syscall_lock); 2548 } 2549 2550 void 2551 swap_pager_status(int *total, int *used) 2552 { 2553 struct swdevt *sp; 2554 2555 *total = 0; 2556 *used = 0; 2557 mtx_lock(&sw_dev_mtx); 2558 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2559 *total += sp->sw_nblks; 2560 *used += sp->sw_used; 2561 } 2562 mtx_unlock(&sw_dev_mtx); 2563 } 2564 2565 int 2566 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2567 { 2568 struct swdevt *sp; 2569 const char *tmp_devname; 2570 int error, n; 2571 2572 n = 0; 2573 error = ENOENT; 2574 mtx_lock(&sw_dev_mtx); 2575 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2576 if (n != name) { 2577 n++; 2578 continue; 2579 } 2580 xs->xsw_version = XSWDEV_VERSION; 2581 xs->xsw_dev = sp->sw_dev; 2582 xs->xsw_flags = sp->sw_flags; 2583 xs->xsw_nblks = sp->sw_nblks; 2584 xs->xsw_used = sp->sw_used; 2585 if (devname != NULL) { 2586 if (vn_isdisk(sp->sw_vp, NULL)) 2587 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2588 else 2589 tmp_devname = "[file]"; 2590 strncpy(devname, tmp_devname, len); 2591 } 2592 error = 0; 2593 break; 2594 } 2595 mtx_unlock(&sw_dev_mtx); 2596 return (error); 2597 } 2598 2599 #if defined(COMPAT_FREEBSD11) 2600 #define XSWDEV_VERSION_11 1 2601 struct xswdev11 { 2602 u_int xsw_version; 2603 uint32_t xsw_dev; 2604 int xsw_flags; 2605 int xsw_nblks; 2606 int xsw_used; 2607 }; 2608 #endif 2609 2610 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2611 struct xswdev32 { 2612 u_int xsw_version; 2613 u_int xsw_dev1, xsw_dev2; 2614 int xsw_flags; 2615 int xsw_nblks; 2616 int xsw_used; 2617 }; 2618 #endif 2619 2620 static int 2621 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2622 { 2623 struct xswdev xs; 2624 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2625 struct xswdev32 xs32; 2626 #endif 2627 #if defined(COMPAT_FREEBSD11) 2628 struct xswdev11 xs11; 2629 #endif 2630 int error; 2631 2632 if (arg2 != 1) /* name length */ 2633 return (EINVAL); 2634 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2635 if (error != 0) 2636 return (error); 2637 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2638 if (req->oldlen == sizeof(xs32)) { 2639 xs32.xsw_version = XSWDEV_VERSION; 2640 xs32.xsw_dev1 = xs.xsw_dev; 2641 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2642 xs32.xsw_flags = xs.xsw_flags; 2643 xs32.xsw_nblks = xs.xsw_nblks; 2644 xs32.xsw_used = xs.xsw_used; 2645 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2646 return (error); 2647 } 2648 #endif 2649 #if defined(COMPAT_FREEBSD11) 2650 if (req->oldlen == sizeof(xs11)) { 2651 xs11.xsw_version = XSWDEV_VERSION_11; 2652 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2653 xs11.xsw_flags = xs.xsw_flags; 2654 xs11.xsw_nblks = xs.xsw_nblks; 2655 xs11.xsw_used = xs.xsw_used; 2656 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2657 return (error); 2658 } 2659 #endif 2660 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2661 return (error); 2662 } 2663 2664 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2665 "Number of swap devices"); 2666 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2667 sysctl_vm_swap_info, 2668 "Swap statistics by device"); 2669 2670 /* 2671 * Count the approximate swap usage in pages for a vmspace. The 2672 * shadowed or not yet copied on write swap blocks are not accounted. 2673 * The map must be locked. 2674 */ 2675 long 2676 vmspace_swap_count(struct vmspace *vmspace) 2677 { 2678 vm_map_t map; 2679 vm_map_entry_t cur; 2680 vm_object_t object; 2681 struct swblk *sb; 2682 vm_pindex_t e, pi; 2683 long count; 2684 int i; 2685 2686 map = &vmspace->vm_map; 2687 count = 0; 2688 2689 VM_MAP_ENTRY_FOREACH(cur, map) { 2690 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2691 continue; 2692 object = cur->object.vm_object; 2693 if (object == NULL || object->type != OBJT_SWAP) 2694 continue; 2695 VM_OBJECT_RLOCK(object); 2696 if (object->type != OBJT_SWAP) 2697 goto unlock; 2698 pi = OFF_TO_IDX(cur->offset); 2699 e = pi + OFF_TO_IDX(cur->end - cur->start); 2700 for (;; pi = sb->p + SWAP_META_PAGES) { 2701 sb = SWAP_PCTRIE_LOOKUP_GE( 2702 &object->un_pager.swp.swp_blks, pi); 2703 if (sb == NULL || sb->p >= e) 2704 break; 2705 for (i = 0; i < SWAP_META_PAGES; i++) { 2706 if (sb->p + i < e && 2707 sb->d[i] != SWAPBLK_NONE) 2708 count++; 2709 } 2710 } 2711 unlock: 2712 VM_OBJECT_RUNLOCK(object); 2713 } 2714 return (count); 2715 } 2716 2717 /* 2718 * GEOM backend 2719 * 2720 * Swapping onto disk devices. 2721 * 2722 */ 2723 2724 static g_orphan_t swapgeom_orphan; 2725 2726 static struct g_class g_swap_class = { 2727 .name = "SWAP", 2728 .version = G_VERSION, 2729 .orphan = swapgeom_orphan, 2730 }; 2731 2732 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2733 2734 2735 static void 2736 swapgeom_close_ev(void *arg, int flags) 2737 { 2738 struct g_consumer *cp; 2739 2740 cp = arg; 2741 g_access(cp, -1, -1, 0); 2742 g_detach(cp); 2743 g_destroy_consumer(cp); 2744 } 2745 2746 /* 2747 * Add a reference to the g_consumer for an inflight transaction. 2748 */ 2749 static void 2750 swapgeom_acquire(struct g_consumer *cp) 2751 { 2752 2753 mtx_assert(&sw_dev_mtx, MA_OWNED); 2754 cp->index++; 2755 } 2756 2757 /* 2758 * Remove a reference from the g_consumer. Post a close event if all 2759 * references go away, since the function might be called from the 2760 * biodone context. 2761 */ 2762 static void 2763 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2764 { 2765 2766 mtx_assert(&sw_dev_mtx, MA_OWNED); 2767 cp->index--; 2768 if (cp->index == 0) { 2769 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2770 sp->sw_id = NULL; 2771 } 2772 } 2773 2774 static void 2775 swapgeom_done(struct bio *bp2) 2776 { 2777 struct swdevt *sp; 2778 struct buf *bp; 2779 struct g_consumer *cp; 2780 2781 bp = bp2->bio_caller2; 2782 cp = bp2->bio_from; 2783 bp->b_ioflags = bp2->bio_flags; 2784 if (bp2->bio_error) 2785 bp->b_ioflags |= BIO_ERROR; 2786 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2787 bp->b_error = bp2->bio_error; 2788 bp->b_caller1 = NULL; 2789 bufdone(bp); 2790 sp = bp2->bio_caller1; 2791 mtx_lock(&sw_dev_mtx); 2792 swapgeom_release(cp, sp); 2793 mtx_unlock(&sw_dev_mtx); 2794 g_destroy_bio(bp2); 2795 } 2796 2797 static void 2798 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2799 { 2800 struct bio *bio; 2801 struct g_consumer *cp; 2802 2803 mtx_lock(&sw_dev_mtx); 2804 cp = sp->sw_id; 2805 if (cp == NULL) { 2806 mtx_unlock(&sw_dev_mtx); 2807 bp->b_error = ENXIO; 2808 bp->b_ioflags |= BIO_ERROR; 2809 bufdone(bp); 2810 return; 2811 } 2812 swapgeom_acquire(cp); 2813 mtx_unlock(&sw_dev_mtx); 2814 if (bp->b_iocmd == BIO_WRITE) 2815 bio = g_new_bio(); 2816 else 2817 bio = g_alloc_bio(); 2818 if (bio == NULL) { 2819 mtx_lock(&sw_dev_mtx); 2820 swapgeom_release(cp, sp); 2821 mtx_unlock(&sw_dev_mtx); 2822 bp->b_error = ENOMEM; 2823 bp->b_ioflags |= BIO_ERROR; 2824 printf("swap_pager: cannot allocate bio\n"); 2825 bufdone(bp); 2826 return; 2827 } 2828 2829 bp->b_caller1 = bio; 2830 bio->bio_caller1 = sp; 2831 bio->bio_caller2 = bp; 2832 bio->bio_cmd = bp->b_iocmd; 2833 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2834 bio->bio_length = bp->b_bcount; 2835 bio->bio_done = swapgeom_done; 2836 if (!buf_mapped(bp)) { 2837 bio->bio_ma = bp->b_pages; 2838 bio->bio_data = unmapped_buf; 2839 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2840 bio->bio_ma_n = bp->b_npages; 2841 bio->bio_flags |= BIO_UNMAPPED; 2842 } else { 2843 bio->bio_data = bp->b_data; 2844 bio->bio_ma = NULL; 2845 } 2846 g_io_request(bio, cp); 2847 return; 2848 } 2849 2850 static void 2851 swapgeom_orphan(struct g_consumer *cp) 2852 { 2853 struct swdevt *sp; 2854 int destroy; 2855 2856 mtx_lock(&sw_dev_mtx); 2857 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2858 if (sp->sw_id == cp) { 2859 sp->sw_flags |= SW_CLOSING; 2860 break; 2861 } 2862 } 2863 /* 2864 * Drop reference we were created with. Do directly since we're in a 2865 * special context where we don't have to queue the call to 2866 * swapgeom_close_ev(). 2867 */ 2868 cp->index--; 2869 destroy = ((sp != NULL) && (cp->index == 0)); 2870 if (destroy) 2871 sp->sw_id = NULL; 2872 mtx_unlock(&sw_dev_mtx); 2873 if (destroy) 2874 swapgeom_close_ev(cp, 0); 2875 } 2876 2877 static void 2878 swapgeom_close(struct thread *td, struct swdevt *sw) 2879 { 2880 struct g_consumer *cp; 2881 2882 mtx_lock(&sw_dev_mtx); 2883 cp = sw->sw_id; 2884 sw->sw_id = NULL; 2885 mtx_unlock(&sw_dev_mtx); 2886 2887 /* 2888 * swapgeom_close() may be called from the biodone context, 2889 * where we cannot perform topology changes. Delegate the 2890 * work to the events thread. 2891 */ 2892 if (cp != NULL) 2893 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2894 } 2895 2896 static int 2897 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2898 { 2899 struct g_provider *pp; 2900 struct g_consumer *cp; 2901 static struct g_geom *gp; 2902 struct swdevt *sp; 2903 u_long nblks; 2904 int error; 2905 2906 pp = g_dev_getprovider(dev); 2907 if (pp == NULL) 2908 return (ENODEV); 2909 mtx_lock(&sw_dev_mtx); 2910 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2911 cp = sp->sw_id; 2912 if (cp != NULL && cp->provider == pp) { 2913 mtx_unlock(&sw_dev_mtx); 2914 return (EBUSY); 2915 } 2916 } 2917 mtx_unlock(&sw_dev_mtx); 2918 if (gp == NULL) 2919 gp = g_new_geomf(&g_swap_class, "swap"); 2920 cp = g_new_consumer(gp); 2921 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2922 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2923 g_attach(cp, pp); 2924 /* 2925 * XXX: Every time you think you can improve the margin for 2926 * footshooting, somebody depends on the ability to do so: 2927 * savecore(8) wants to write to our swapdev so we cannot 2928 * set an exclusive count :-( 2929 */ 2930 error = g_access(cp, 1, 1, 0); 2931 if (error != 0) { 2932 g_detach(cp); 2933 g_destroy_consumer(cp); 2934 return (error); 2935 } 2936 nblks = pp->mediasize / DEV_BSIZE; 2937 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2938 swapgeom_close, dev2udev(dev), 2939 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2940 return (0); 2941 } 2942 2943 static int 2944 swapongeom(struct vnode *vp) 2945 { 2946 int error; 2947 2948 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2949 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 2950 error = ENOENT; 2951 } else { 2952 g_topology_lock(); 2953 error = swapongeom_locked(vp->v_rdev, vp); 2954 g_topology_unlock(); 2955 } 2956 VOP_UNLOCK(vp); 2957 return (error); 2958 } 2959 2960 /* 2961 * VNODE backend 2962 * 2963 * This is used mainly for network filesystem (read: probably only tested 2964 * with NFS) swapfiles. 2965 * 2966 */ 2967 2968 static void 2969 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2970 { 2971 struct vnode *vp2; 2972 2973 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2974 2975 vp2 = sp->sw_id; 2976 vhold(vp2); 2977 if (bp->b_iocmd == BIO_WRITE) { 2978 if (bp->b_bufobj) 2979 bufobj_wdrop(bp->b_bufobj); 2980 bufobj_wref(&vp2->v_bufobj); 2981 } 2982 if (bp->b_bufobj != &vp2->v_bufobj) 2983 bp->b_bufobj = &vp2->v_bufobj; 2984 bp->b_vp = vp2; 2985 bp->b_iooffset = dbtob(bp->b_blkno); 2986 bstrategy(bp); 2987 return; 2988 } 2989 2990 static void 2991 swapdev_close(struct thread *td, struct swdevt *sp) 2992 { 2993 2994 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2995 vrele(sp->sw_vp); 2996 } 2997 2998 2999 static int 3000 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3001 { 3002 struct swdevt *sp; 3003 int error; 3004 3005 if (nblks == 0) 3006 return (ENXIO); 3007 mtx_lock(&sw_dev_mtx); 3008 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3009 if (sp->sw_id == vp) { 3010 mtx_unlock(&sw_dev_mtx); 3011 return (EBUSY); 3012 } 3013 } 3014 mtx_unlock(&sw_dev_mtx); 3015 3016 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3017 #ifdef MAC 3018 error = mac_system_check_swapon(td->td_ucred, vp); 3019 if (error == 0) 3020 #endif 3021 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3022 (void) VOP_UNLOCK(vp); 3023 if (error) 3024 return (error); 3025 3026 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3027 NODEV, 0); 3028 return (0); 3029 } 3030 3031 static int 3032 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3033 { 3034 int error, new, n; 3035 3036 new = nsw_wcount_async_max; 3037 error = sysctl_handle_int(oidp, &new, 0, req); 3038 if (error != 0 || req->newptr == NULL) 3039 return (error); 3040 3041 if (new > nswbuf / 2 || new < 1) 3042 return (EINVAL); 3043 3044 mtx_lock(&swbuf_mtx); 3045 while (nsw_wcount_async_max != new) { 3046 /* 3047 * Adjust difference. If the current async count is too low, 3048 * we will need to sqeeze our update slowly in. Sleep with a 3049 * higher priority than getpbuf() to finish faster. 3050 */ 3051 n = new - nsw_wcount_async_max; 3052 if (nsw_wcount_async + n >= 0) { 3053 nsw_wcount_async += n; 3054 nsw_wcount_async_max += n; 3055 wakeup(&nsw_wcount_async); 3056 } else { 3057 nsw_wcount_async_max -= nsw_wcount_async; 3058 nsw_wcount_async = 0; 3059 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3060 "swpsysctl", 0); 3061 } 3062 } 3063 mtx_unlock(&swbuf_mtx); 3064 3065 return (0); 3066 } 3067 3068 static void 3069 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3070 vm_offset_t end) 3071 { 3072 3073 VM_OBJECT_WLOCK(object); 3074 KASSERT((object->flags & OBJ_ANON) == 0, 3075 ("Splittable object with writecount")); 3076 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3077 VM_OBJECT_WUNLOCK(object); 3078 } 3079 3080 static void 3081 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3082 vm_offset_t end) 3083 { 3084 3085 VM_OBJECT_WLOCK(object); 3086 KASSERT((object->flags & OBJ_ANON) == 0, 3087 ("Splittable object with writecount")); 3088 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3089 VM_OBJECT_WUNLOCK(object); 3090 } 3091