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 __exclusive_cache_line 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_DEFINE_EARLY(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_DEFINE_EARLY(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 static bool 206 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) 207 { 208 struct uidinfo *uip; 209 u_long prev; 210 211 uip = cred->cr_ruidinfo; 212 213 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 214 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && 215 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 216 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { 217 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 218 KASSERT(prev >= pincr, ("negative vmsize for uid = %d\n", uip->ui_uid)); 219 return (false); 220 } 221 return (true); 222 } 223 224 static void 225 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) 226 { 227 struct uidinfo *uip; 228 #ifdef INVARIANTS 229 u_long prev; 230 #endif 231 232 uip = cred->cr_ruidinfo; 233 234 #ifdef INVARIANTS 235 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 236 KASSERT(prev >= pdecr, ("negative vmsize for uid = %d\n", uip->ui_uid)); 237 #else 238 atomic_subtract_long(&uip->ui_vmsize, pdecr); 239 #endif 240 } 241 242 static void 243 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) 244 { 245 struct uidinfo *uip; 246 247 uip = cred->cr_ruidinfo; 248 atomic_add_long(&uip->ui_vmsize, pincr); 249 } 250 251 bool 252 swap_reserve(vm_ooffset_t incr) 253 { 254 255 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 256 } 257 258 bool 259 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 260 { 261 u_long r, s, prev, pincr; 262 #ifdef RACCT 263 int error; 264 #endif 265 int oc; 266 static int curfail; 267 static struct timeval lastfail; 268 269 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 270 (uintmax_t)incr)); 271 272 #ifdef RACCT 273 if (RACCT_ENABLED()) { 274 PROC_LOCK(curproc); 275 error = racct_add(curproc, RACCT_SWAP, incr); 276 PROC_UNLOCK(curproc); 277 if (error != 0) 278 return (false); 279 } 280 #endif 281 282 pincr = atop(incr); 283 prev = atomic_fetchadd_long(&swap_reserved, pincr); 284 r = prev + pincr; 285 s = swap_total; 286 oc = atomic_load_int(&overcommit); 287 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { 288 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - 289 vm_wire_count(); 290 } 291 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && 292 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { 293 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 294 KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); 295 goto out_error; 296 } 297 298 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { 299 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 300 KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); 301 goto out_error; 302 } 303 304 return (true); 305 306 out_error: 307 if (ppsratecheck(&lastfail, &curfail, 1)) { 308 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 309 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); 310 } 311 #ifdef RACCT 312 if (RACCT_ENABLED()) { 313 PROC_LOCK(curproc); 314 racct_sub(curproc, RACCT_SWAP, incr); 315 PROC_UNLOCK(curproc); 316 } 317 #endif 318 319 return (false); 320 } 321 322 void 323 swap_reserve_force(vm_ooffset_t incr) 324 { 325 u_long pincr; 326 327 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 328 (uintmax_t)incr)); 329 330 #ifdef RACCT 331 if (RACCT_ENABLED()) { 332 PROC_LOCK(curproc); 333 racct_add_force(curproc, RACCT_SWAP, incr); 334 PROC_UNLOCK(curproc); 335 } 336 #endif 337 pincr = atop(incr); 338 atomic_add_long(&swap_reserved, pincr); 339 swap_reserve_force_rlimit(pincr, curthread->td_ucred); 340 } 341 342 void 343 swap_release(vm_ooffset_t decr) 344 { 345 struct ucred *cred; 346 347 PROC_LOCK(curproc); 348 cred = curproc->p_ucred; 349 swap_release_by_cred(decr, cred); 350 PROC_UNLOCK(curproc); 351 } 352 353 void 354 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 355 { 356 u_long pdecr; 357 #ifdef INVARIANTS 358 u_long prev; 359 #endif 360 361 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 362 (uintmax_t)decr)); 363 364 pdecr = atop(decr); 365 #ifdef INVARIANTS 366 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 367 KASSERT(prev >= pdecr, ("swap_reserved < decr")); 368 #else 369 atomic_subtract_long(&swap_reserved, pdecr); 370 #endif 371 372 swap_release_by_cred_rlimit(pdecr, cred); 373 #ifdef RACCT 374 if (racct_enable) 375 racct_sub_cred(cred, RACCT_SWAP, decr); 376 #endif 377 } 378 379 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 380 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 381 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 382 static int nsw_wcount_async; /* limit async write buffers */ 383 static int nsw_wcount_async_max;/* assigned maximum */ 384 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 385 386 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 387 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 388 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 389 "Maximum running async swap ops"); 390 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 391 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 392 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 393 "Swap Fragmentation Info"); 394 395 static struct sx sw_alloc_sx; 396 397 /* 398 * "named" and "unnamed" anon region objects. Try to reduce the overhead 399 * of searching a named list by hashing it just a little. 400 */ 401 402 #define NOBJLISTS 8 403 404 #define NOBJLIST(handle) \ 405 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 406 407 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 408 static uma_zone_t swwbuf_zone; 409 static uma_zone_t swrbuf_zone; 410 static uma_zone_t swblk_zone; 411 static uma_zone_t swpctrie_zone; 412 413 /* 414 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 415 * calls hooked from other parts of the VM system and do not appear here. 416 * (see vm/swap_pager.h). 417 */ 418 static vm_object_t 419 swap_pager_alloc(void *handle, vm_ooffset_t size, 420 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 421 static void swap_pager_dealloc(vm_object_t object); 422 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 423 int *); 424 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 425 int *, pgo_getpages_iodone_t, void *); 426 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 427 static boolean_t 428 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 429 static void swap_pager_init(void); 430 static void swap_pager_unswapped(vm_page_t); 431 static void swap_pager_swapoff(struct swdevt *sp); 432 static void swap_pager_update_writecount(vm_object_t object, 433 vm_offset_t start, vm_offset_t end); 434 static void swap_pager_release_writecount(vm_object_t object, 435 vm_offset_t start, vm_offset_t end); 436 437 struct pagerops swappagerops = { 438 .pgo_init = swap_pager_init, /* early system initialization of pager */ 439 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 440 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 441 .pgo_getpages = swap_pager_getpages, /* pagein */ 442 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 443 .pgo_putpages = swap_pager_putpages, /* pageout */ 444 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 445 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 446 .pgo_update_writecount = swap_pager_update_writecount, 447 .pgo_release_writecount = swap_pager_release_writecount, 448 }; 449 450 /* 451 * swap_*() routines are externally accessible. swp_*() routines are 452 * internal. 453 */ 454 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 455 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 456 457 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 458 "Maximum size of a swap block in pages"); 459 460 static void swp_sizecheck(void); 461 static void swp_pager_async_iodone(struct buf *bp); 462 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 463 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 464 static int swapongeom(struct vnode *); 465 static int swaponvp(struct thread *, struct vnode *, u_long); 466 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 467 468 /* 469 * Swap bitmap functions 470 */ 471 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 472 static daddr_t swp_pager_getswapspace(int *npages); 473 474 /* 475 * Metadata functions 476 */ 477 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 478 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 479 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 480 vm_pindex_t pindex, vm_pindex_t count); 481 static void swp_pager_meta_free_all(vm_object_t); 482 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 483 484 static void 485 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 486 { 487 488 *start = SWAPBLK_NONE; 489 *num = 0; 490 } 491 492 static void 493 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 494 { 495 496 if (*start + *num == addr) { 497 (*num)++; 498 } else { 499 swp_pager_freeswapspace(*start, *num); 500 *start = addr; 501 *num = 1; 502 } 503 } 504 505 static void * 506 swblk_trie_alloc(struct pctrie *ptree) 507 { 508 509 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 510 M_USE_RESERVE : 0))); 511 } 512 513 static void 514 swblk_trie_free(struct pctrie *ptree, void *node) 515 { 516 517 uma_zfree(swpctrie_zone, node); 518 } 519 520 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 521 522 /* 523 * SWP_SIZECHECK() - update swap_pager_full indication 524 * 525 * update the swap_pager_almost_full indication and warn when we are 526 * about to run out of swap space, using lowat/hiwat hysteresis. 527 * 528 * Clear swap_pager_full ( task killing ) indication when lowat is met. 529 * 530 * No restrictions on call 531 * This routine may not block. 532 */ 533 static void 534 swp_sizecheck(void) 535 { 536 537 if (swap_pager_avail < nswap_lowat) { 538 if (swap_pager_almost_full == 0) { 539 printf("swap_pager: out of swap space\n"); 540 swap_pager_almost_full = 1; 541 } 542 } else { 543 swap_pager_full = 0; 544 if (swap_pager_avail > nswap_hiwat) 545 swap_pager_almost_full = 0; 546 } 547 } 548 549 /* 550 * SWAP_PAGER_INIT() - initialize the swap pager! 551 * 552 * Expected to be started from system init. NOTE: This code is run 553 * before much else so be careful what you depend on. Most of the VM 554 * system has yet to be initialized at this point. 555 */ 556 static void 557 swap_pager_init(void) 558 { 559 /* 560 * Initialize object lists 561 */ 562 int i; 563 564 for (i = 0; i < NOBJLISTS; ++i) 565 TAILQ_INIT(&swap_pager_object_list[i]); 566 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 567 sx_init(&sw_alloc_sx, "swspsx"); 568 sx_init(&swdev_syscall_lock, "swsysc"); 569 } 570 571 /* 572 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 573 * 574 * Expected to be started from pageout process once, prior to entering 575 * its main loop. 576 */ 577 void 578 swap_pager_swap_init(void) 579 { 580 unsigned long n, n2; 581 582 /* 583 * Number of in-transit swap bp operations. Don't 584 * exhaust the pbufs completely. Make sure we 585 * initialize workable values (0 will work for hysteresis 586 * but it isn't very efficient). 587 * 588 * The nsw_cluster_max is constrained by the bp->b_pages[] 589 * array, which has maxphys / PAGE_SIZE entries, and our locally 590 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 591 * constrained by the swap device interleave stripe size. 592 * 593 * Currently we hardwire nsw_wcount_async to 4. This limit is 594 * designed to prevent other I/O from having high latencies due to 595 * our pageout I/O. The value 4 works well for one or two active swap 596 * devices but is probably a little low if you have more. Even so, 597 * a higher value would probably generate only a limited improvement 598 * with three or four active swap devices since the system does not 599 * typically have to pageout at extreme bandwidths. We will want 600 * at least 2 per swap devices, and 4 is a pretty good value if you 601 * have one NFS swap device due to the command/ack latency over NFS. 602 * So it all works out pretty well. 603 */ 604 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 605 606 nsw_wcount_async = 4; 607 nsw_wcount_async_max = nsw_wcount_async; 608 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 609 610 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 611 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 612 613 /* 614 * Initialize our zone, taking the user's requested size or 615 * estimating the number we need based on the number of pages 616 * in the system. 617 */ 618 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 619 vm_cnt.v_page_count / 2; 620 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 621 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 622 if (swpctrie_zone == NULL) 623 panic("failed to create swap pctrie zone."); 624 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 625 NULL, NULL, _Alignof(struct swblk) - 1, 0); 626 if (swblk_zone == NULL) 627 panic("failed to create swap blk zone."); 628 n2 = n; 629 do { 630 if (uma_zone_reserve_kva(swblk_zone, n)) 631 break; 632 /* 633 * if the allocation failed, try a zone two thirds the 634 * size of the previous attempt. 635 */ 636 n -= ((n + 2) / 3); 637 } while (n > 0); 638 639 /* 640 * Often uma_zone_reserve_kva() cannot reserve exactly the 641 * requested size. Account for the difference when 642 * calculating swap_maxpages. 643 */ 644 n = uma_zone_get_max(swblk_zone); 645 646 if (n < n2) 647 printf("Swap blk zone entries changed from %lu to %lu.\n", 648 n2, n); 649 /* absolute maximum we can handle assuming 100% efficiency */ 650 swap_maxpages = n * SWAP_META_PAGES; 651 swzone = n * sizeof(struct swblk); 652 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 653 printf("Cannot reserve swap pctrie zone, " 654 "reduce kern.maxswzone.\n"); 655 } 656 657 static vm_object_t 658 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 659 vm_ooffset_t offset) 660 { 661 vm_object_t object; 662 663 if (cred != NULL) { 664 if (!swap_reserve_by_cred(size, cred)) 665 return (NULL); 666 crhold(cred); 667 } 668 669 /* 670 * The un_pager.swp.swp_blks trie is initialized by 671 * vm_object_allocate() to ensure the correct order of 672 * visibility to other threads. 673 */ 674 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 675 PAGE_MASK + size)); 676 677 object->un_pager.swp.writemappings = 0; 678 object->handle = handle; 679 if (cred != NULL) { 680 object->cred = cred; 681 object->charge = size; 682 } 683 return (object); 684 } 685 686 /* 687 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 688 * its metadata structures. 689 * 690 * This routine is called from the mmap and fork code to create a new 691 * OBJT_SWAP object. 692 * 693 * This routine must ensure that no live duplicate is created for 694 * the named object request, which is protected against by 695 * holding the sw_alloc_sx lock in case handle != NULL. 696 */ 697 static vm_object_t 698 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 699 vm_ooffset_t offset, struct ucred *cred) 700 { 701 vm_object_t object; 702 703 if (handle != NULL) { 704 /* 705 * Reference existing named region or allocate new one. There 706 * should not be a race here against swp_pager_meta_build() 707 * as called from vm_page_remove() in regards to the lookup 708 * of the handle. 709 */ 710 sx_xlock(&sw_alloc_sx); 711 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 712 if (object == NULL) { 713 object = swap_pager_alloc_init(handle, cred, size, 714 offset); 715 if (object != NULL) { 716 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 717 object, pager_object_list); 718 } 719 } 720 sx_xunlock(&sw_alloc_sx); 721 } else { 722 object = swap_pager_alloc_init(handle, cred, size, offset); 723 } 724 return (object); 725 } 726 727 /* 728 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 729 * 730 * The swap backing for the object is destroyed. The code is 731 * designed such that we can reinstantiate it later, but this 732 * routine is typically called only when the entire object is 733 * about to be destroyed. 734 * 735 * The object must be locked. 736 */ 737 static void 738 swap_pager_dealloc(vm_object_t object) 739 { 740 741 VM_OBJECT_ASSERT_WLOCKED(object); 742 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 743 744 /* 745 * Remove from list right away so lookups will fail if we block for 746 * pageout completion. 747 */ 748 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 749 VM_OBJECT_WUNLOCK(object); 750 sx_xlock(&sw_alloc_sx); 751 TAILQ_REMOVE(NOBJLIST(object->handle), object, 752 pager_object_list); 753 sx_xunlock(&sw_alloc_sx); 754 VM_OBJECT_WLOCK(object); 755 } 756 757 vm_object_pip_wait(object, "swpdea"); 758 759 /* 760 * Free all remaining metadata. We only bother to free it from 761 * the swap meta data. We do not attempt to free swapblk's still 762 * associated with vm_page_t's for this object. We do not care 763 * if paging is still in progress on some objects. 764 */ 765 swp_pager_meta_free_all(object); 766 object->handle = NULL; 767 object->type = OBJT_DEAD; 768 } 769 770 /************************************************************************ 771 * SWAP PAGER BITMAP ROUTINES * 772 ************************************************************************/ 773 774 /* 775 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 776 * 777 * Allocate swap for up to the requested number of pages. The 778 * starting swap block number (a page index) is returned or 779 * SWAPBLK_NONE if the allocation failed. 780 * 781 * Also has the side effect of advising that somebody made a mistake 782 * when they configured swap and didn't configure enough. 783 * 784 * This routine may not sleep. 785 * 786 * We allocate in round-robin fashion from the configured devices. 787 */ 788 static daddr_t 789 swp_pager_getswapspace(int *io_npages) 790 { 791 daddr_t blk; 792 struct swdevt *sp; 793 int mpages, npages; 794 795 KASSERT(*io_npages >= 1, 796 ("%s: npages not positive", __func__)); 797 blk = SWAPBLK_NONE; 798 mpages = *io_npages; 799 npages = imin(BLIST_MAX_ALLOC, mpages); 800 mtx_lock(&sw_dev_mtx); 801 sp = swdevhd; 802 while (!TAILQ_EMPTY(&swtailq)) { 803 if (sp == NULL) 804 sp = TAILQ_FIRST(&swtailq); 805 if ((sp->sw_flags & SW_CLOSING) == 0) 806 blk = blist_alloc(sp->sw_blist, &npages, mpages); 807 if (blk != SWAPBLK_NONE) 808 break; 809 sp = TAILQ_NEXT(sp, sw_list); 810 if (swdevhd == sp) { 811 if (npages == 1) 812 break; 813 mpages = npages - 1; 814 npages >>= 1; 815 } 816 } 817 if (blk != SWAPBLK_NONE) { 818 *io_npages = npages; 819 blk += sp->sw_first; 820 sp->sw_used += npages; 821 swap_pager_avail -= npages; 822 swp_sizecheck(); 823 swdevhd = TAILQ_NEXT(sp, sw_list); 824 } else { 825 if (swap_pager_full != 2) { 826 printf("swp_pager_getswapspace(%d): failed\n", 827 *io_npages); 828 swap_pager_full = 2; 829 swap_pager_almost_full = 1; 830 } 831 swdevhd = NULL; 832 } 833 mtx_unlock(&sw_dev_mtx); 834 return (blk); 835 } 836 837 static bool 838 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 839 { 840 841 return (blk >= sp->sw_first && blk < sp->sw_end); 842 } 843 844 static void 845 swp_pager_strategy(struct buf *bp) 846 { 847 struct swdevt *sp; 848 849 mtx_lock(&sw_dev_mtx); 850 TAILQ_FOREACH(sp, &swtailq, sw_list) { 851 if (swp_pager_isondev(bp->b_blkno, sp)) { 852 mtx_unlock(&sw_dev_mtx); 853 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 854 unmapped_buf_allowed) { 855 bp->b_data = unmapped_buf; 856 bp->b_offset = 0; 857 } else { 858 pmap_qenter((vm_offset_t)bp->b_data, 859 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 860 } 861 sp->sw_strategy(bp, sp); 862 return; 863 } 864 } 865 panic("Swapdev not found"); 866 } 867 868 /* 869 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 870 * 871 * This routine returns the specified swap blocks back to the bitmap. 872 * 873 * This routine may not sleep. 874 */ 875 static void 876 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 877 { 878 struct swdevt *sp; 879 880 if (npages == 0) 881 return; 882 mtx_lock(&sw_dev_mtx); 883 TAILQ_FOREACH(sp, &swtailq, sw_list) { 884 if (swp_pager_isondev(blk, sp)) { 885 sp->sw_used -= npages; 886 /* 887 * If we are attempting to stop swapping on 888 * this device, we don't want to mark any 889 * blocks free lest they be reused. 890 */ 891 if ((sp->sw_flags & SW_CLOSING) == 0) { 892 blist_free(sp->sw_blist, blk - sp->sw_first, 893 npages); 894 swap_pager_avail += npages; 895 swp_sizecheck(); 896 } 897 mtx_unlock(&sw_dev_mtx); 898 return; 899 } 900 } 901 panic("Swapdev not found"); 902 } 903 904 /* 905 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 906 */ 907 static int 908 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 909 { 910 struct sbuf sbuf; 911 struct swdevt *sp; 912 const char *devname; 913 int error; 914 915 error = sysctl_wire_old_buffer(req, 0); 916 if (error != 0) 917 return (error); 918 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 919 mtx_lock(&sw_dev_mtx); 920 TAILQ_FOREACH(sp, &swtailq, sw_list) { 921 if (vn_isdisk(sp->sw_vp)) 922 devname = devtoname(sp->sw_vp->v_rdev); 923 else 924 devname = "[file]"; 925 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 926 blist_stats(sp->sw_blist, &sbuf); 927 } 928 mtx_unlock(&sw_dev_mtx); 929 error = sbuf_finish(&sbuf); 930 sbuf_delete(&sbuf); 931 return (error); 932 } 933 934 /* 935 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 936 * range within an object. 937 * 938 * This is a globally accessible routine. 939 * 940 * This routine removes swapblk assignments from swap metadata. 941 * 942 * The external callers of this routine typically have already destroyed 943 * or renamed vm_page_t's associated with this range in the object so 944 * we should be ok. 945 * 946 * The object must be locked. 947 */ 948 void 949 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 950 { 951 952 swp_pager_meta_free(object, start, size); 953 } 954 955 /* 956 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 957 * 958 * Assigns swap blocks to the specified range within the object. The 959 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 960 * 961 * Returns 0 on success, -1 on failure. 962 */ 963 int 964 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 965 { 966 daddr_t addr, blk, n_free, s_free; 967 int i, j, n; 968 969 swp_pager_init_freerange(&s_free, &n_free); 970 VM_OBJECT_WLOCK(object); 971 for (i = 0; i < size; i += n) { 972 n = size - i; 973 blk = swp_pager_getswapspace(&n); 974 if (blk == SWAPBLK_NONE) { 975 swp_pager_meta_free(object, start, i); 976 VM_OBJECT_WUNLOCK(object); 977 return (-1); 978 } 979 for (j = 0; j < n; ++j) { 980 addr = swp_pager_meta_build(object, 981 start + i + j, blk + j); 982 if (addr != SWAPBLK_NONE) 983 swp_pager_update_freerange(&s_free, &n_free, 984 addr); 985 } 986 } 987 swp_pager_freeswapspace(s_free, n_free); 988 VM_OBJECT_WUNLOCK(object); 989 return (0); 990 } 991 992 static bool 993 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 994 vm_pindex_t pindex, daddr_t addr) 995 { 996 daddr_t dstaddr; 997 998 KASSERT(srcobject->type == OBJT_SWAP, 999 ("%s: Srcobject not swappable", __func__)); 1000 if (dstobject->type == OBJT_SWAP && 1001 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 1002 /* Caller should destroy the source block. */ 1003 return (false); 1004 } 1005 1006 /* 1007 * Destination has no swapblk and is not resident, transfer source. 1008 * swp_pager_meta_build() can sleep. 1009 */ 1010 VM_OBJECT_WUNLOCK(srcobject); 1011 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 1012 KASSERT(dstaddr == SWAPBLK_NONE, 1013 ("Unexpected destination swapblk")); 1014 VM_OBJECT_WLOCK(srcobject); 1015 1016 return (true); 1017 } 1018 1019 /* 1020 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 1021 * and destroy the source. 1022 * 1023 * Copy any valid swapblks from the source to the destination. In 1024 * cases where both the source and destination have a valid swapblk, 1025 * we keep the destination's. 1026 * 1027 * This routine is allowed to sleep. It may sleep allocating metadata 1028 * indirectly through swp_pager_meta_build(). 1029 * 1030 * The source object contains no vm_page_t's (which is just as well) 1031 * 1032 * The source object is of type OBJT_SWAP. 1033 * 1034 * The source and destination objects must be locked. 1035 * Both object locks may temporarily be released. 1036 */ 1037 void 1038 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1039 vm_pindex_t offset, int destroysource) 1040 { 1041 1042 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1043 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1044 1045 /* 1046 * If destroysource is set, we remove the source object from the 1047 * swap_pager internal queue now. 1048 */ 1049 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1050 srcobject->handle != NULL) { 1051 VM_OBJECT_WUNLOCK(srcobject); 1052 VM_OBJECT_WUNLOCK(dstobject); 1053 sx_xlock(&sw_alloc_sx); 1054 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1055 pager_object_list); 1056 sx_xunlock(&sw_alloc_sx); 1057 VM_OBJECT_WLOCK(dstobject); 1058 VM_OBJECT_WLOCK(srcobject); 1059 } 1060 1061 /* 1062 * Transfer source to destination. 1063 */ 1064 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1065 1066 /* 1067 * Free left over swap blocks in source. 1068 * 1069 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1070 * double-remove the object from the swap queues. 1071 */ 1072 if (destroysource) { 1073 swp_pager_meta_free_all(srcobject); 1074 /* 1075 * Reverting the type is not necessary, the caller is going 1076 * to destroy srcobject directly, but I'm doing it here 1077 * for consistency since we've removed the object from its 1078 * queues. 1079 */ 1080 srcobject->type = OBJT_DEFAULT; 1081 } 1082 } 1083 1084 /* 1085 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1086 * the requested page. 1087 * 1088 * We determine whether good backing store exists for the requested 1089 * page and return TRUE if it does, FALSE if it doesn't. 1090 * 1091 * If TRUE, we also try to determine how much valid, contiguous backing 1092 * store exists before and after the requested page. 1093 */ 1094 static boolean_t 1095 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1096 int *after) 1097 { 1098 daddr_t blk, blk0; 1099 int i; 1100 1101 VM_OBJECT_ASSERT_LOCKED(object); 1102 KASSERT(object->type == OBJT_SWAP, 1103 ("%s: object not swappable", __func__)); 1104 1105 /* 1106 * do we have good backing store at the requested index ? 1107 */ 1108 blk0 = swp_pager_meta_lookup(object, pindex); 1109 if (blk0 == SWAPBLK_NONE) { 1110 if (before) 1111 *before = 0; 1112 if (after) 1113 *after = 0; 1114 return (FALSE); 1115 } 1116 1117 /* 1118 * find backwards-looking contiguous good backing store 1119 */ 1120 if (before != NULL) { 1121 for (i = 1; i < SWB_NPAGES; i++) { 1122 if (i > pindex) 1123 break; 1124 blk = swp_pager_meta_lookup(object, pindex - i); 1125 if (blk != blk0 - i) 1126 break; 1127 } 1128 *before = i - 1; 1129 } 1130 1131 /* 1132 * find forward-looking contiguous good backing store 1133 */ 1134 if (after != NULL) { 1135 for (i = 1; i < SWB_NPAGES; i++) { 1136 blk = swp_pager_meta_lookup(object, pindex + i); 1137 if (blk != blk0 + i) 1138 break; 1139 } 1140 *after = i - 1; 1141 } 1142 return (TRUE); 1143 } 1144 1145 /* 1146 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1147 * 1148 * This removes any associated swap backing store, whether valid or 1149 * not, from the page. 1150 * 1151 * This routine is typically called when a page is made dirty, at 1152 * which point any associated swap can be freed. MADV_FREE also 1153 * calls us in a special-case situation 1154 * 1155 * NOTE!!! If the page is clean and the swap was valid, the caller 1156 * should make the page dirty before calling this routine. This routine 1157 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1158 * depends on it. 1159 * 1160 * This routine may not sleep. 1161 * 1162 * The object containing the page may be locked. 1163 */ 1164 static void 1165 swap_pager_unswapped(vm_page_t m) 1166 { 1167 struct swblk *sb; 1168 vm_object_t obj; 1169 1170 /* 1171 * Handle enqueing deferred frees first. If we do not have the 1172 * object lock we wait for the page daemon to clear the space. 1173 */ 1174 obj = m->object; 1175 if (!VM_OBJECT_WOWNED(obj)) { 1176 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1177 /* 1178 * The caller is responsible for synchronization but we 1179 * will harmlessly handle races. This is typically provided 1180 * by only calling unswapped() when a page transitions from 1181 * clean to dirty. 1182 */ 1183 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1184 PGA_SWAP_SPACE) { 1185 vm_page_aflag_set(m, PGA_SWAP_FREE); 1186 counter_u64_add(swap_free_deferred, 1); 1187 } 1188 return; 1189 } 1190 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1191 counter_u64_add(swap_free_completed, 1); 1192 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1193 1194 /* 1195 * The meta data only exists if the object is OBJT_SWAP 1196 * and even then might not be allocated yet. 1197 */ 1198 KASSERT(m->object->type == OBJT_SWAP, 1199 ("Free object not swappable")); 1200 1201 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1202 rounddown(m->pindex, SWAP_META_PAGES)); 1203 if (sb == NULL) 1204 return; 1205 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1206 return; 1207 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1208 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1209 swp_pager_free_empty_swblk(m->object, sb); 1210 } 1211 1212 /* 1213 * swap_pager_getpages() - bring pages in from swap 1214 * 1215 * Attempt to page in the pages in array "ma" of length "count". The 1216 * caller may optionally specify that additional pages preceding and 1217 * succeeding the specified range be paged in. The number of such pages 1218 * is returned in the "rbehind" and "rahead" parameters, and they will 1219 * be in the inactive queue upon return. 1220 * 1221 * The pages in "ma" must be busied and will remain busied upon return. 1222 */ 1223 static int 1224 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1225 int *rbehind, int *rahead) 1226 { 1227 struct buf *bp; 1228 vm_page_t bm, mpred, msucc, p; 1229 vm_pindex_t pindex; 1230 daddr_t blk; 1231 int i, maxahead, maxbehind, reqcount; 1232 1233 VM_OBJECT_ASSERT_WLOCKED(object); 1234 reqcount = count; 1235 1236 KASSERT(object->type == OBJT_SWAP, 1237 ("%s: object not swappable", __func__)); 1238 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1239 VM_OBJECT_WUNLOCK(object); 1240 return (VM_PAGER_FAIL); 1241 } 1242 1243 KASSERT(reqcount - 1 <= maxahead, 1244 ("page count %d extends beyond swap block", reqcount)); 1245 1246 /* 1247 * Do not transfer any pages other than those that are xbusied 1248 * when running during a split or collapse operation. This 1249 * prevents clustering from re-creating pages which are being 1250 * moved into another object. 1251 */ 1252 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1253 maxahead = reqcount - 1; 1254 maxbehind = 0; 1255 } 1256 1257 /* 1258 * Clip the readahead and readbehind ranges to exclude resident pages. 1259 */ 1260 if (rahead != NULL) { 1261 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1262 pindex = ma[reqcount - 1]->pindex; 1263 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1264 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1265 *rahead = msucc->pindex - pindex - 1; 1266 } 1267 if (rbehind != NULL) { 1268 *rbehind = imin(*rbehind, maxbehind); 1269 pindex = ma[0]->pindex; 1270 mpred = TAILQ_PREV(ma[0], pglist, listq); 1271 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1272 *rbehind = pindex - mpred->pindex - 1; 1273 } 1274 1275 bm = ma[0]; 1276 for (i = 0; i < count; i++) 1277 ma[i]->oflags |= VPO_SWAPINPROG; 1278 1279 /* 1280 * Allocate readahead and readbehind pages. 1281 */ 1282 if (rbehind != NULL) { 1283 for (i = 1; i <= *rbehind; i++) { 1284 p = vm_page_alloc(object, ma[0]->pindex - i, 1285 VM_ALLOC_NORMAL); 1286 if (p == NULL) 1287 break; 1288 p->oflags |= VPO_SWAPINPROG; 1289 bm = p; 1290 } 1291 *rbehind = i - 1; 1292 } 1293 if (rahead != NULL) { 1294 for (i = 0; i < *rahead; i++) { 1295 p = vm_page_alloc(object, 1296 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1297 if (p == NULL) 1298 break; 1299 p->oflags |= VPO_SWAPINPROG; 1300 } 1301 *rahead = i; 1302 } 1303 if (rbehind != NULL) 1304 count += *rbehind; 1305 if (rahead != NULL) 1306 count += *rahead; 1307 1308 vm_object_pip_add(object, count); 1309 1310 pindex = bm->pindex; 1311 blk = swp_pager_meta_lookup(object, pindex); 1312 KASSERT(blk != SWAPBLK_NONE, 1313 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1314 1315 VM_OBJECT_WUNLOCK(object); 1316 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1317 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1318 /* Pages cannot leave the object while busy. */ 1319 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1320 MPASS(p->pindex == bm->pindex + i); 1321 bp->b_pages[i] = p; 1322 } 1323 1324 bp->b_flags |= B_PAGING; 1325 bp->b_iocmd = BIO_READ; 1326 bp->b_iodone = swp_pager_async_iodone; 1327 bp->b_rcred = crhold(thread0.td_ucred); 1328 bp->b_wcred = crhold(thread0.td_ucred); 1329 bp->b_blkno = blk; 1330 bp->b_bcount = PAGE_SIZE * count; 1331 bp->b_bufsize = PAGE_SIZE * count; 1332 bp->b_npages = count; 1333 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1334 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1335 1336 VM_CNT_INC(v_swapin); 1337 VM_CNT_ADD(v_swappgsin, count); 1338 1339 /* 1340 * perform the I/O. NOTE!!! bp cannot be considered valid after 1341 * this point because we automatically release it on completion. 1342 * Instead, we look at the one page we are interested in which we 1343 * still hold a lock on even through the I/O completion. 1344 * 1345 * The other pages in our ma[] array are also released on completion, 1346 * so we cannot assume they are valid anymore either. 1347 * 1348 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1349 */ 1350 BUF_KERNPROC(bp); 1351 swp_pager_strategy(bp); 1352 1353 /* 1354 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1355 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1356 * is set in the metadata for each page in the request. 1357 */ 1358 VM_OBJECT_WLOCK(object); 1359 /* This could be implemented more efficiently with aflags */ 1360 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1361 ma[0]->oflags |= VPO_SWAPSLEEP; 1362 VM_CNT_INC(v_intrans); 1363 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1364 "swread", hz * 20)) { 1365 printf( 1366 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1367 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1368 } 1369 } 1370 VM_OBJECT_WUNLOCK(object); 1371 1372 /* 1373 * If we had an unrecoverable read error pages will not be valid. 1374 */ 1375 for (i = 0; i < reqcount; i++) 1376 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1377 return (VM_PAGER_ERROR); 1378 1379 return (VM_PAGER_OK); 1380 1381 /* 1382 * A final note: in a low swap situation, we cannot deallocate swap 1383 * and mark a page dirty here because the caller is likely to mark 1384 * the page clean when we return, causing the page to possibly revert 1385 * to all-zero's later. 1386 */ 1387 } 1388 1389 static int 1390 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1391 int *rbehind, int *rahead) 1392 { 1393 1394 VM_OBJECT_WLOCK(object); 1395 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1396 } 1397 1398 /* 1399 * swap_pager_getpages_async(): 1400 * 1401 * Right now this is emulation of asynchronous operation on top of 1402 * swap_pager_getpages(). 1403 */ 1404 static int 1405 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1406 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1407 { 1408 int r, error; 1409 1410 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1411 switch (r) { 1412 case VM_PAGER_OK: 1413 error = 0; 1414 break; 1415 case VM_PAGER_ERROR: 1416 error = EIO; 1417 break; 1418 case VM_PAGER_FAIL: 1419 error = EINVAL; 1420 break; 1421 default: 1422 panic("unhandled swap_pager_getpages() error %d", r); 1423 } 1424 (iodone)(arg, ma, count, error); 1425 1426 return (r); 1427 } 1428 1429 /* 1430 * swap_pager_putpages: 1431 * 1432 * Assign swap (if necessary) and initiate I/O on the specified pages. 1433 * 1434 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1435 * are automatically converted to SWAP objects. 1436 * 1437 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1438 * vm_page reservation system coupled with properly written VFS devices 1439 * should ensure that no low-memory deadlock occurs. This is an area 1440 * which needs work. 1441 * 1442 * The parent has N vm_object_pip_add() references prior to 1443 * calling us and will remove references for rtvals[] that are 1444 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1445 * completion. 1446 * 1447 * The parent has soft-busy'd the pages it passes us and will unbusy 1448 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1449 * We need to unbusy the rest on I/O completion. 1450 */ 1451 static void 1452 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1453 int flags, int *rtvals) 1454 { 1455 struct buf *bp; 1456 daddr_t addr, blk, n_free, s_free; 1457 vm_page_t mreq; 1458 int i, j, n; 1459 bool async; 1460 1461 KASSERT(count == 0 || ma[0]->object == object, 1462 ("%s: object mismatch %p/%p", 1463 __func__, object, ma[0]->object)); 1464 1465 /* 1466 * Step 1 1467 * 1468 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1469 */ 1470 if (object->type != OBJT_SWAP) { 1471 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1472 KASSERT(addr == SWAPBLK_NONE, 1473 ("unexpected object swap block")); 1474 } 1475 VM_OBJECT_WUNLOCK(object); 1476 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1477 swp_pager_init_freerange(&s_free, &n_free); 1478 1479 /* 1480 * Step 2 1481 * 1482 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1483 * The page is left dirty until the pageout operation completes 1484 * successfully. 1485 */ 1486 for (i = 0; i < count; i += n) { 1487 /* Maximum I/O size is limited by maximum swap block size. */ 1488 n = min(count - i, nsw_cluster_max); 1489 1490 if (async) { 1491 mtx_lock(&swbuf_mtx); 1492 while (nsw_wcount_async == 0) 1493 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1494 "swbufa", 0); 1495 nsw_wcount_async--; 1496 mtx_unlock(&swbuf_mtx); 1497 } 1498 1499 /* Get a block of swap of size up to size n. */ 1500 VM_OBJECT_WLOCK(object); 1501 blk = swp_pager_getswapspace(&n); 1502 if (blk == SWAPBLK_NONE) { 1503 VM_OBJECT_WUNLOCK(object); 1504 mtx_lock(&swbuf_mtx); 1505 if (++nsw_wcount_async == 1) 1506 wakeup(&nsw_wcount_async); 1507 mtx_unlock(&swbuf_mtx); 1508 for (j = 0; j < n; ++j) 1509 rtvals[i + j] = VM_PAGER_FAIL; 1510 continue; 1511 } 1512 for (j = 0; j < n; ++j) { 1513 mreq = ma[i + j]; 1514 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1515 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1516 blk + j); 1517 if (addr != SWAPBLK_NONE) 1518 swp_pager_update_freerange(&s_free, &n_free, 1519 addr); 1520 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1521 mreq->oflags |= VPO_SWAPINPROG; 1522 } 1523 VM_OBJECT_WUNLOCK(object); 1524 1525 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1526 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1527 if (async) 1528 bp->b_flags |= B_ASYNC; 1529 bp->b_flags |= B_PAGING; 1530 bp->b_iocmd = BIO_WRITE; 1531 1532 bp->b_rcred = crhold(thread0.td_ucred); 1533 bp->b_wcred = crhold(thread0.td_ucred); 1534 bp->b_bcount = PAGE_SIZE * n; 1535 bp->b_bufsize = PAGE_SIZE * n; 1536 bp->b_blkno = blk; 1537 for (j = 0; j < n; j++) 1538 bp->b_pages[j] = ma[i + j]; 1539 bp->b_npages = n; 1540 1541 /* 1542 * Must set dirty range for NFS to work. 1543 */ 1544 bp->b_dirtyoff = 0; 1545 bp->b_dirtyend = bp->b_bcount; 1546 1547 VM_CNT_INC(v_swapout); 1548 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1549 1550 /* 1551 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1552 * can call the async completion routine at the end of a 1553 * synchronous I/O operation. Otherwise, our caller would 1554 * perform duplicate unbusy and wakeup operations on the page 1555 * and object, respectively. 1556 */ 1557 for (j = 0; j < n; j++) 1558 rtvals[i + j] = VM_PAGER_PEND; 1559 1560 /* 1561 * asynchronous 1562 * 1563 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1564 */ 1565 if (async) { 1566 bp->b_iodone = swp_pager_async_iodone; 1567 BUF_KERNPROC(bp); 1568 swp_pager_strategy(bp); 1569 continue; 1570 } 1571 1572 /* 1573 * synchronous 1574 * 1575 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1576 */ 1577 bp->b_iodone = bdone; 1578 swp_pager_strategy(bp); 1579 1580 /* 1581 * Wait for the sync I/O to complete. 1582 */ 1583 bwait(bp, PVM, "swwrt"); 1584 1585 /* 1586 * Now that we are through with the bp, we can call the 1587 * normal async completion, which frees everything up. 1588 */ 1589 swp_pager_async_iodone(bp); 1590 } 1591 swp_pager_freeswapspace(s_free, n_free); 1592 VM_OBJECT_WLOCK(object); 1593 } 1594 1595 /* 1596 * swp_pager_async_iodone: 1597 * 1598 * Completion routine for asynchronous reads and writes from/to swap. 1599 * Also called manually by synchronous code to finish up a bp. 1600 * 1601 * This routine may not sleep. 1602 */ 1603 static void 1604 swp_pager_async_iodone(struct buf *bp) 1605 { 1606 int i; 1607 vm_object_t object = NULL; 1608 1609 /* 1610 * Report error - unless we ran out of memory, in which case 1611 * we've already logged it in swapgeom_strategy(). 1612 */ 1613 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1614 printf( 1615 "swap_pager: I/O error - %s failed; blkno %ld," 1616 "size %ld, error %d\n", 1617 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1618 (long)bp->b_blkno, 1619 (long)bp->b_bcount, 1620 bp->b_error 1621 ); 1622 } 1623 1624 /* 1625 * remove the mapping for kernel virtual 1626 */ 1627 if (buf_mapped(bp)) 1628 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1629 else 1630 bp->b_data = bp->b_kvabase; 1631 1632 if (bp->b_npages) { 1633 object = bp->b_pages[0]->object; 1634 VM_OBJECT_WLOCK(object); 1635 } 1636 1637 /* 1638 * cleanup pages. If an error occurs writing to swap, we are in 1639 * very serious trouble. If it happens to be a disk error, though, 1640 * we may be able to recover by reassigning the swap later on. So 1641 * in this case we remove the m->swapblk assignment for the page 1642 * but do not free it in the rlist. The errornous block(s) are thus 1643 * never reallocated as swap. Redirty the page and continue. 1644 */ 1645 for (i = 0; i < bp->b_npages; ++i) { 1646 vm_page_t m = bp->b_pages[i]; 1647 1648 m->oflags &= ~VPO_SWAPINPROG; 1649 if (m->oflags & VPO_SWAPSLEEP) { 1650 m->oflags &= ~VPO_SWAPSLEEP; 1651 wakeup(&object->handle); 1652 } 1653 1654 /* We always have space after I/O, successful or not. */ 1655 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1656 1657 if (bp->b_ioflags & BIO_ERROR) { 1658 /* 1659 * If an error occurs I'd love to throw the swapblk 1660 * away without freeing it back to swapspace, so it 1661 * can never be used again. But I can't from an 1662 * interrupt. 1663 */ 1664 if (bp->b_iocmd == BIO_READ) { 1665 /* 1666 * NOTE: for reads, m->dirty will probably 1667 * be overridden by the original caller of 1668 * getpages so don't play cute tricks here. 1669 */ 1670 vm_page_invalid(m); 1671 } else { 1672 /* 1673 * If a write error occurs, reactivate page 1674 * so it doesn't clog the inactive list, 1675 * then finish the I/O. 1676 */ 1677 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1678 1679 /* PQ_UNSWAPPABLE? */ 1680 vm_page_activate(m); 1681 vm_page_sunbusy(m); 1682 } 1683 } else if (bp->b_iocmd == BIO_READ) { 1684 /* 1685 * NOTE: for reads, m->dirty will probably be 1686 * overridden by the original caller of getpages so 1687 * we cannot set them in order to free the underlying 1688 * swap in a low-swap situation. I don't think we'd 1689 * want to do that anyway, but it was an optimization 1690 * that existed in the old swapper for a time before 1691 * it got ripped out due to precisely this problem. 1692 */ 1693 KASSERT(!pmap_page_is_mapped(m), 1694 ("swp_pager_async_iodone: page %p is mapped", m)); 1695 KASSERT(m->dirty == 0, 1696 ("swp_pager_async_iodone: page %p is dirty", m)); 1697 1698 vm_page_valid(m); 1699 if (i < bp->b_pgbefore || 1700 i >= bp->b_npages - bp->b_pgafter) 1701 vm_page_readahead_finish(m); 1702 } else { 1703 /* 1704 * For write success, clear the dirty 1705 * status, then finish the I/O ( which decrements the 1706 * busy count and possibly wakes waiter's up ). 1707 * A page is only written to swap after a period of 1708 * inactivity. Therefore, we do not expect it to be 1709 * reused. 1710 */ 1711 KASSERT(!pmap_page_is_write_mapped(m), 1712 ("swp_pager_async_iodone: page %p is not write" 1713 " protected", m)); 1714 vm_page_undirty(m); 1715 vm_page_deactivate_noreuse(m); 1716 vm_page_sunbusy(m); 1717 } 1718 } 1719 1720 /* 1721 * adjust pip. NOTE: the original parent may still have its own 1722 * pip refs on the object. 1723 */ 1724 if (object != NULL) { 1725 vm_object_pip_wakeupn(object, bp->b_npages); 1726 VM_OBJECT_WUNLOCK(object); 1727 } 1728 1729 /* 1730 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1731 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1732 * trigger a KASSERT in relpbuf(). 1733 */ 1734 if (bp->b_vp) { 1735 bp->b_vp = NULL; 1736 bp->b_bufobj = NULL; 1737 } 1738 /* 1739 * release the physical I/O buffer 1740 */ 1741 if (bp->b_flags & B_ASYNC) { 1742 mtx_lock(&swbuf_mtx); 1743 if (++nsw_wcount_async == 1) 1744 wakeup(&nsw_wcount_async); 1745 mtx_unlock(&swbuf_mtx); 1746 } 1747 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1748 } 1749 1750 int 1751 swap_pager_nswapdev(void) 1752 { 1753 1754 return (nswapdev); 1755 } 1756 1757 static void 1758 swp_pager_force_dirty(vm_page_t m) 1759 { 1760 1761 vm_page_dirty(m); 1762 swap_pager_unswapped(m); 1763 vm_page_launder(m); 1764 } 1765 1766 u_long 1767 swap_pager_swapped_pages(vm_object_t object) 1768 { 1769 struct swblk *sb; 1770 vm_pindex_t pi; 1771 u_long res; 1772 int i; 1773 1774 VM_OBJECT_ASSERT_LOCKED(object); 1775 if (object->type != OBJT_SWAP) 1776 return (0); 1777 1778 for (res = 0, pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1779 &object->un_pager.swp.swp_blks, pi)) != NULL; 1780 pi = sb->p + SWAP_META_PAGES) { 1781 for (i = 0; i < SWAP_META_PAGES; i++) { 1782 if (sb->d[i] != SWAPBLK_NONE) 1783 res++; 1784 } 1785 } 1786 return (res); 1787 } 1788 1789 /* 1790 * swap_pager_swapoff_object: 1791 * 1792 * Page in all of the pages that have been paged out for an object 1793 * to a swap device. 1794 */ 1795 static void 1796 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1797 { 1798 struct swblk *sb; 1799 vm_page_t m; 1800 vm_pindex_t pi; 1801 daddr_t blk; 1802 int i, nv, rahead, rv; 1803 1804 KASSERT(object->type == OBJT_SWAP, 1805 ("%s: Object not swappable", __func__)); 1806 1807 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1808 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1809 if ((object->flags & OBJ_DEAD) != 0) { 1810 /* 1811 * Make sure that pending writes finish before 1812 * returning. 1813 */ 1814 vm_object_pip_wait(object, "swpoff"); 1815 swp_pager_meta_free_all(object); 1816 break; 1817 } 1818 for (i = 0; i < SWAP_META_PAGES; i++) { 1819 /* 1820 * Count the number of contiguous valid blocks. 1821 */ 1822 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1823 blk = sb->d[i + nv]; 1824 if (!swp_pager_isondev(blk, sp) || 1825 blk == SWAPBLK_NONE) 1826 break; 1827 } 1828 if (nv == 0) 1829 continue; 1830 1831 /* 1832 * Look for a page corresponding to the first 1833 * valid block and ensure that any pending paging 1834 * operations on it are complete. If the page is valid, 1835 * mark it dirty and free the swap block. Try to batch 1836 * this operation since it may cause sp to be freed, 1837 * meaning that we must restart the scan. Avoid busying 1838 * valid pages since we may block forever on kernel 1839 * stack pages. 1840 */ 1841 m = vm_page_lookup(object, sb->p + i); 1842 if (m == NULL) { 1843 m = vm_page_alloc(object, sb->p + i, 1844 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1845 if (m == NULL) 1846 break; 1847 } else { 1848 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1849 m->oflags |= VPO_SWAPSLEEP; 1850 VM_OBJECT_SLEEP(object, &object->handle, 1851 PSWP, "swpoff", 0); 1852 break; 1853 } 1854 if (vm_page_all_valid(m)) { 1855 do { 1856 swp_pager_force_dirty(m); 1857 } while (--nv > 0 && 1858 (m = vm_page_next(m)) != NULL && 1859 vm_page_all_valid(m) && 1860 (m->oflags & VPO_SWAPINPROG) == 0); 1861 break; 1862 } 1863 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1864 break; 1865 } 1866 1867 vm_object_pip_add(object, 1); 1868 rahead = SWAP_META_PAGES; 1869 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1870 &rahead); 1871 if (rv != VM_PAGER_OK) 1872 panic("%s: read from swap failed: %d", 1873 __func__, rv); 1874 vm_object_pip_wakeupn(object, 1); 1875 VM_OBJECT_WLOCK(object); 1876 vm_page_xunbusy(m); 1877 1878 /* 1879 * The object lock was dropped so we must restart the 1880 * scan of this swap block. Pages paged in during this 1881 * iteration will be marked dirty in a future iteration. 1882 */ 1883 break; 1884 } 1885 if (i == SWAP_META_PAGES) 1886 pi = sb->p + SWAP_META_PAGES; 1887 } 1888 } 1889 1890 /* 1891 * swap_pager_swapoff: 1892 * 1893 * Page in all of the pages that have been paged out to the 1894 * given device. The corresponding blocks in the bitmap must be 1895 * marked as allocated and the device must be flagged SW_CLOSING. 1896 * There may be no processes swapped out to the device. 1897 * 1898 * This routine may block. 1899 */ 1900 static void 1901 swap_pager_swapoff(struct swdevt *sp) 1902 { 1903 vm_object_t object; 1904 int retries; 1905 1906 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1907 1908 retries = 0; 1909 full_rescan: 1910 mtx_lock(&vm_object_list_mtx); 1911 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1912 if (object->type != OBJT_SWAP) 1913 continue; 1914 mtx_unlock(&vm_object_list_mtx); 1915 /* Depends on type-stability. */ 1916 VM_OBJECT_WLOCK(object); 1917 1918 /* 1919 * Dead objects are eventually terminated on their own. 1920 */ 1921 if ((object->flags & OBJ_DEAD) != 0) 1922 goto next_obj; 1923 1924 /* 1925 * Sync with fences placed after pctrie 1926 * initialization. We must not access pctrie below 1927 * unless we checked that our object is swap and not 1928 * dead. 1929 */ 1930 atomic_thread_fence_acq(); 1931 if (object->type != OBJT_SWAP) 1932 goto next_obj; 1933 1934 swap_pager_swapoff_object(sp, object); 1935 next_obj: 1936 VM_OBJECT_WUNLOCK(object); 1937 mtx_lock(&vm_object_list_mtx); 1938 } 1939 mtx_unlock(&vm_object_list_mtx); 1940 1941 if (sp->sw_used) { 1942 /* 1943 * Objects may be locked or paging to the device being 1944 * removed, so we will miss their pages and need to 1945 * make another pass. We have marked this device as 1946 * SW_CLOSING, so the activity should finish soon. 1947 */ 1948 retries++; 1949 if (retries > 100) { 1950 panic("swapoff: failed to locate %d swap blocks", 1951 sp->sw_used); 1952 } 1953 pause("swpoff", hz / 20); 1954 goto full_rescan; 1955 } 1956 EVENTHANDLER_INVOKE(swapoff, sp); 1957 } 1958 1959 /************************************************************************ 1960 * SWAP META DATA * 1961 ************************************************************************ 1962 * 1963 * These routines manipulate the swap metadata stored in the 1964 * OBJT_SWAP object. 1965 * 1966 * Swap metadata is implemented with a global hash and not directly 1967 * linked into the object. Instead the object simply contains 1968 * appropriate tracking counters. 1969 */ 1970 1971 /* 1972 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1973 */ 1974 static bool 1975 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1976 { 1977 int i; 1978 1979 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1980 for (i = start; i < limit; i++) { 1981 if (sb->d[i] != SWAPBLK_NONE) 1982 return (false); 1983 } 1984 return (true); 1985 } 1986 1987 /* 1988 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1989 * 1990 * Nothing is done if the block is still in use. 1991 */ 1992 static void 1993 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1994 { 1995 1996 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1997 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1998 uma_zfree(swblk_zone, sb); 1999 } 2000 } 2001 2002 /* 2003 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2004 * 2005 * We first convert the object to a swap object if it is a default 2006 * object. 2007 * 2008 * The specified swapblk is added to the object's swap metadata. If 2009 * the swapblk is not valid, it is freed instead. Any previously 2010 * assigned swapblk is returned. 2011 */ 2012 static daddr_t 2013 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 2014 { 2015 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 2016 struct swblk *sb, *sb1; 2017 vm_pindex_t modpi, rdpi; 2018 daddr_t prev_swapblk; 2019 int error, i; 2020 2021 VM_OBJECT_ASSERT_WLOCKED(object); 2022 2023 /* 2024 * Convert default object to swap object if necessary 2025 */ 2026 if (object->type != OBJT_SWAP) { 2027 pctrie_init(&object->un_pager.swp.swp_blks); 2028 2029 /* 2030 * Ensure that swap_pager_swapoff()'s iteration over 2031 * object_list does not see a garbage pctrie. 2032 */ 2033 atomic_thread_fence_rel(); 2034 2035 object->type = OBJT_SWAP; 2036 object->un_pager.swp.writemappings = 0; 2037 KASSERT((object->flags & OBJ_ANON) != 0 || 2038 object->handle == NULL, 2039 ("default pager %p with handle %p", 2040 object, object->handle)); 2041 } 2042 2043 rdpi = rounddown(pindex, SWAP_META_PAGES); 2044 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 2045 if (sb == NULL) { 2046 if (swapblk == SWAPBLK_NONE) 2047 return (SWAPBLK_NONE); 2048 for (;;) { 2049 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 2050 pageproc ? M_USE_RESERVE : 0)); 2051 if (sb != NULL) { 2052 sb->p = rdpi; 2053 for (i = 0; i < SWAP_META_PAGES; i++) 2054 sb->d[i] = SWAPBLK_NONE; 2055 if (atomic_cmpset_int(&swblk_zone_exhausted, 2056 1, 0)) 2057 printf("swblk zone ok\n"); 2058 break; 2059 } 2060 VM_OBJECT_WUNLOCK(object); 2061 if (uma_zone_exhausted(swblk_zone)) { 2062 if (atomic_cmpset_int(&swblk_zone_exhausted, 2063 0, 1)) 2064 printf("swap blk zone exhausted, " 2065 "increase kern.maxswzone\n"); 2066 vm_pageout_oom(VM_OOM_SWAPZ); 2067 pause("swzonxb", 10); 2068 } else 2069 uma_zwait(swblk_zone); 2070 VM_OBJECT_WLOCK(object); 2071 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2072 rdpi); 2073 if (sb != NULL) 2074 /* 2075 * Somebody swapped out a nearby page, 2076 * allocating swblk at the rdpi index, 2077 * while we dropped the object lock. 2078 */ 2079 goto allocated; 2080 } 2081 for (;;) { 2082 error = SWAP_PCTRIE_INSERT( 2083 &object->un_pager.swp.swp_blks, sb); 2084 if (error == 0) { 2085 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2086 1, 0)) 2087 printf("swpctrie zone ok\n"); 2088 break; 2089 } 2090 VM_OBJECT_WUNLOCK(object); 2091 if (uma_zone_exhausted(swpctrie_zone)) { 2092 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2093 0, 1)) 2094 printf("swap pctrie zone exhausted, " 2095 "increase kern.maxswzone\n"); 2096 vm_pageout_oom(VM_OOM_SWAPZ); 2097 pause("swzonxp", 10); 2098 } else 2099 uma_zwait(swpctrie_zone); 2100 VM_OBJECT_WLOCK(object); 2101 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2102 rdpi); 2103 if (sb1 != NULL) { 2104 uma_zfree(swblk_zone, sb); 2105 sb = sb1; 2106 goto allocated; 2107 } 2108 } 2109 } 2110 allocated: 2111 MPASS(sb->p == rdpi); 2112 2113 modpi = pindex % SWAP_META_PAGES; 2114 /* Return prior contents of metadata. */ 2115 prev_swapblk = sb->d[modpi]; 2116 /* Enter block into metadata. */ 2117 sb->d[modpi] = swapblk; 2118 2119 /* 2120 * Free the swblk if we end up with the empty page run. 2121 */ 2122 if (swapblk == SWAPBLK_NONE) 2123 swp_pager_free_empty_swblk(object, sb); 2124 return (prev_swapblk); 2125 } 2126 2127 /* 2128 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2129 * metadata, or transfer it into dstobject. 2130 * 2131 * This routine will free swap metadata structures as they are cleaned 2132 * out. 2133 */ 2134 static void 2135 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2136 vm_pindex_t pindex, vm_pindex_t count) 2137 { 2138 struct swblk *sb; 2139 daddr_t n_free, s_free; 2140 vm_pindex_t offset, last; 2141 int i, limit, start; 2142 2143 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2144 if (srcobject->type != OBJT_SWAP || count == 0) 2145 return; 2146 2147 swp_pager_init_freerange(&s_free, &n_free); 2148 offset = pindex; 2149 last = pindex + count; 2150 for (;;) { 2151 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2152 rounddown(pindex, SWAP_META_PAGES)); 2153 if (sb == NULL || sb->p >= last) 2154 break; 2155 start = pindex > sb->p ? pindex - sb->p : 0; 2156 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2157 SWAP_META_PAGES; 2158 for (i = start; i < limit; i++) { 2159 if (sb->d[i] == SWAPBLK_NONE) 2160 continue; 2161 if (dstobject == NULL || 2162 !swp_pager_xfer_source(srcobject, dstobject, 2163 sb->p + i - offset, sb->d[i])) { 2164 swp_pager_update_freerange(&s_free, &n_free, 2165 sb->d[i]); 2166 } 2167 sb->d[i] = SWAPBLK_NONE; 2168 } 2169 pindex = sb->p + SWAP_META_PAGES; 2170 if (swp_pager_swblk_empty(sb, 0, start) && 2171 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2172 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2173 sb->p); 2174 uma_zfree(swblk_zone, sb); 2175 } 2176 } 2177 swp_pager_freeswapspace(s_free, n_free); 2178 } 2179 2180 /* 2181 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2182 * 2183 * The requested range of blocks is freed, with any associated swap 2184 * returned to the swap bitmap. 2185 * 2186 * This routine will free swap metadata structures as they are cleaned 2187 * out. This routine does *NOT* operate on swap metadata associated 2188 * with resident pages. 2189 */ 2190 static void 2191 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2192 { 2193 swp_pager_meta_transfer(object, NULL, pindex, count); 2194 } 2195 2196 /* 2197 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2198 * 2199 * This routine locates and destroys all swap metadata associated with 2200 * an object. 2201 */ 2202 static void 2203 swp_pager_meta_free_all(vm_object_t object) 2204 { 2205 struct swblk *sb; 2206 daddr_t n_free, s_free; 2207 vm_pindex_t pindex; 2208 int i; 2209 2210 VM_OBJECT_ASSERT_WLOCKED(object); 2211 if (object->type != OBJT_SWAP) 2212 return; 2213 2214 swp_pager_init_freerange(&s_free, &n_free); 2215 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2216 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2217 pindex = sb->p + SWAP_META_PAGES; 2218 for (i = 0; i < SWAP_META_PAGES; i++) { 2219 if (sb->d[i] == SWAPBLK_NONE) 2220 continue; 2221 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2222 } 2223 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2224 uma_zfree(swblk_zone, sb); 2225 } 2226 swp_pager_freeswapspace(s_free, n_free); 2227 } 2228 2229 /* 2230 * SWP_PAGER_METACTL() - misc control of swap meta data. 2231 * 2232 * This routine is capable of looking up, or removing swapblk 2233 * assignments in the swap meta data. It returns the swapblk being 2234 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2235 * 2236 * When acting on a busy resident page and paging is in progress, we 2237 * have to wait until paging is complete but otherwise can act on the 2238 * busy page. 2239 */ 2240 static daddr_t 2241 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2242 { 2243 struct swblk *sb; 2244 2245 VM_OBJECT_ASSERT_LOCKED(object); 2246 2247 /* 2248 * The meta data only exists if the object is OBJT_SWAP 2249 * and even then might not be allocated yet. 2250 */ 2251 KASSERT(object->type == OBJT_SWAP, 2252 ("Lookup object not swappable")); 2253 2254 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2255 rounddown(pindex, SWAP_META_PAGES)); 2256 if (sb == NULL) 2257 return (SWAPBLK_NONE); 2258 return (sb->d[pindex % SWAP_META_PAGES]); 2259 } 2260 2261 /* 2262 * Returns the least page index which is greater than or equal to the 2263 * parameter pindex and for which there is a swap block allocated. 2264 * Returns object's size if the object's type is not swap or if there 2265 * are no allocated swap blocks for the object after the requested 2266 * pindex. 2267 */ 2268 vm_pindex_t 2269 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2270 { 2271 struct swblk *sb; 2272 int i; 2273 2274 VM_OBJECT_ASSERT_LOCKED(object); 2275 if (object->type != OBJT_SWAP) 2276 return (object->size); 2277 2278 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2279 rounddown(pindex, SWAP_META_PAGES)); 2280 if (sb == NULL) 2281 return (object->size); 2282 if (sb->p < pindex) { 2283 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2284 if (sb->d[i] != SWAPBLK_NONE) 2285 return (sb->p + i); 2286 } 2287 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2288 roundup(pindex, SWAP_META_PAGES)); 2289 if (sb == NULL) 2290 return (object->size); 2291 } 2292 for (i = 0; i < SWAP_META_PAGES; i++) { 2293 if (sb->d[i] != SWAPBLK_NONE) 2294 return (sb->p + i); 2295 } 2296 2297 /* 2298 * We get here if a swblk is present in the trie but it 2299 * doesn't map any blocks. 2300 */ 2301 MPASS(0); 2302 return (object->size); 2303 } 2304 2305 /* 2306 * System call swapon(name) enables swapping on device name, 2307 * which must be in the swdevsw. Return EBUSY 2308 * if already swapping on this device. 2309 */ 2310 #ifndef _SYS_SYSPROTO_H_ 2311 struct swapon_args { 2312 char *name; 2313 }; 2314 #endif 2315 2316 /* 2317 * MPSAFE 2318 */ 2319 /* ARGSUSED */ 2320 int 2321 sys_swapon(struct thread *td, struct swapon_args *uap) 2322 { 2323 struct vattr attr; 2324 struct vnode *vp; 2325 struct nameidata nd; 2326 int error; 2327 2328 error = priv_check(td, PRIV_SWAPON); 2329 if (error) 2330 return (error); 2331 2332 sx_xlock(&swdev_syscall_lock); 2333 2334 /* 2335 * Swap metadata may not fit in the KVM if we have physical 2336 * memory of >1GB. 2337 */ 2338 if (swblk_zone == NULL) { 2339 error = ENOMEM; 2340 goto done; 2341 } 2342 2343 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2344 uap->name, td); 2345 error = namei(&nd); 2346 if (error) 2347 goto done; 2348 2349 NDFREE(&nd, NDF_ONLY_PNBUF); 2350 vp = nd.ni_vp; 2351 2352 if (vn_isdisk_error(vp, &error)) { 2353 error = swapongeom(vp); 2354 } else if (vp->v_type == VREG && 2355 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2356 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2357 /* 2358 * Allow direct swapping to NFS regular files in the same 2359 * way that nfs_mountroot() sets up diskless swapping. 2360 */ 2361 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2362 } 2363 2364 if (error) 2365 vrele(vp); 2366 done: 2367 sx_xunlock(&swdev_syscall_lock); 2368 return (error); 2369 } 2370 2371 /* 2372 * Check that the total amount of swap currently configured does not 2373 * exceed half the theoretical maximum. If it does, print a warning 2374 * message. 2375 */ 2376 static void 2377 swapon_check_swzone(void) 2378 { 2379 2380 /* recommend using no more than half that amount */ 2381 if (swap_total > swap_maxpages / 2) { 2382 printf("warning: total configured swap (%lu pages) " 2383 "exceeds maximum recommended amount (%lu pages).\n", 2384 swap_total, swap_maxpages / 2); 2385 printf("warning: increase kern.maxswzone " 2386 "or reduce amount of swap.\n"); 2387 } 2388 } 2389 2390 static void 2391 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2392 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2393 { 2394 struct swdevt *sp, *tsp; 2395 daddr_t dvbase; 2396 2397 /* 2398 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2399 * First chop nblks off to page-align it, then convert. 2400 * 2401 * sw->sw_nblks is in page-sized chunks now too. 2402 */ 2403 nblks &= ~(ctodb(1) - 1); 2404 nblks = dbtoc(nblks); 2405 2406 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2407 sp->sw_blist = blist_create(nblks, M_WAITOK); 2408 sp->sw_vp = vp; 2409 sp->sw_id = id; 2410 sp->sw_dev = dev; 2411 sp->sw_nblks = nblks; 2412 sp->sw_used = 0; 2413 sp->sw_strategy = strategy; 2414 sp->sw_close = close; 2415 sp->sw_flags = flags; 2416 2417 /* 2418 * Do not free the first blocks in order to avoid overwriting 2419 * any bsd label at the front of the partition 2420 */ 2421 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2422 nblks - howmany(BBSIZE, PAGE_SIZE)); 2423 2424 dvbase = 0; 2425 mtx_lock(&sw_dev_mtx); 2426 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2427 if (tsp->sw_end >= dvbase) { 2428 /* 2429 * We put one uncovered page between the devices 2430 * in order to definitively prevent any cross-device 2431 * I/O requests 2432 */ 2433 dvbase = tsp->sw_end + 1; 2434 } 2435 } 2436 sp->sw_first = dvbase; 2437 sp->sw_end = dvbase + nblks; 2438 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2439 nswapdev++; 2440 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2441 swap_total += nblks; 2442 swapon_check_swzone(); 2443 swp_sizecheck(); 2444 mtx_unlock(&sw_dev_mtx); 2445 EVENTHANDLER_INVOKE(swapon, sp); 2446 } 2447 2448 /* 2449 * SYSCALL: swapoff(devname) 2450 * 2451 * Disable swapping on the given device. 2452 * 2453 * XXX: Badly designed system call: it should use a device index 2454 * rather than filename as specification. We keep sw_vp around 2455 * only to make this work. 2456 */ 2457 #ifndef _SYS_SYSPROTO_H_ 2458 struct swapoff_args { 2459 char *name; 2460 }; 2461 #endif 2462 2463 /* 2464 * MPSAFE 2465 */ 2466 /* ARGSUSED */ 2467 int 2468 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2469 { 2470 struct vnode *vp; 2471 struct nameidata nd; 2472 struct swdevt *sp; 2473 int error; 2474 2475 error = priv_check(td, PRIV_SWAPOFF); 2476 if (error) 2477 return (error); 2478 2479 sx_xlock(&swdev_syscall_lock); 2480 2481 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2482 td); 2483 error = namei(&nd); 2484 if (error) 2485 goto done; 2486 NDFREE(&nd, NDF_ONLY_PNBUF); 2487 vp = nd.ni_vp; 2488 2489 mtx_lock(&sw_dev_mtx); 2490 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2491 if (sp->sw_vp == vp) 2492 break; 2493 } 2494 mtx_unlock(&sw_dev_mtx); 2495 if (sp == NULL) { 2496 error = EINVAL; 2497 goto done; 2498 } 2499 error = swapoff_one(sp, td->td_ucred); 2500 done: 2501 sx_xunlock(&swdev_syscall_lock); 2502 return (error); 2503 } 2504 2505 static int 2506 swapoff_one(struct swdevt *sp, struct ucred *cred) 2507 { 2508 u_long nblks; 2509 #ifdef MAC 2510 int error; 2511 #endif 2512 2513 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2514 #ifdef MAC 2515 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2516 error = mac_system_check_swapoff(cred, sp->sw_vp); 2517 (void) VOP_UNLOCK(sp->sw_vp); 2518 if (error != 0) 2519 return (error); 2520 #endif 2521 nblks = sp->sw_nblks; 2522 2523 /* 2524 * We can turn off this swap device safely only if the 2525 * available virtual memory in the system will fit the amount 2526 * of data we will have to page back in, plus an epsilon so 2527 * the system doesn't become critically low on swap space. 2528 */ 2529 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2530 return (ENOMEM); 2531 2532 /* 2533 * Prevent further allocations on this device. 2534 */ 2535 mtx_lock(&sw_dev_mtx); 2536 sp->sw_flags |= SW_CLOSING; 2537 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2538 swap_total -= nblks; 2539 mtx_unlock(&sw_dev_mtx); 2540 2541 /* 2542 * Page in the contents of the device and close it. 2543 */ 2544 swap_pager_swapoff(sp); 2545 2546 sp->sw_close(curthread, sp); 2547 mtx_lock(&sw_dev_mtx); 2548 sp->sw_id = NULL; 2549 TAILQ_REMOVE(&swtailq, sp, sw_list); 2550 nswapdev--; 2551 if (nswapdev == 0) { 2552 swap_pager_full = 2; 2553 swap_pager_almost_full = 1; 2554 } 2555 if (swdevhd == sp) 2556 swdevhd = NULL; 2557 mtx_unlock(&sw_dev_mtx); 2558 blist_destroy(sp->sw_blist); 2559 free(sp, M_VMPGDATA); 2560 return (0); 2561 } 2562 2563 void 2564 swapoff_all(void) 2565 { 2566 struct swdevt *sp, *spt; 2567 const char *devname; 2568 int error; 2569 2570 sx_xlock(&swdev_syscall_lock); 2571 2572 mtx_lock(&sw_dev_mtx); 2573 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2574 mtx_unlock(&sw_dev_mtx); 2575 if (vn_isdisk(sp->sw_vp)) 2576 devname = devtoname(sp->sw_vp->v_rdev); 2577 else 2578 devname = "[file]"; 2579 error = swapoff_one(sp, thread0.td_ucred); 2580 if (error != 0) { 2581 printf("Cannot remove swap device %s (error=%d), " 2582 "skipping.\n", devname, error); 2583 } else if (bootverbose) { 2584 printf("Swap device %s removed.\n", devname); 2585 } 2586 mtx_lock(&sw_dev_mtx); 2587 } 2588 mtx_unlock(&sw_dev_mtx); 2589 2590 sx_xunlock(&swdev_syscall_lock); 2591 } 2592 2593 void 2594 swap_pager_status(int *total, int *used) 2595 { 2596 2597 *total = swap_total; 2598 *used = swap_total - swap_pager_avail - 2599 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2600 } 2601 2602 int 2603 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2604 { 2605 struct swdevt *sp; 2606 const char *tmp_devname; 2607 int error, n; 2608 2609 n = 0; 2610 error = ENOENT; 2611 mtx_lock(&sw_dev_mtx); 2612 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2613 if (n != name) { 2614 n++; 2615 continue; 2616 } 2617 xs->xsw_version = XSWDEV_VERSION; 2618 xs->xsw_dev = sp->sw_dev; 2619 xs->xsw_flags = sp->sw_flags; 2620 xs->xsw_nblks = sp->sw_nblks; 2621 xs->xsw_used = sp->sw_used; 2622 if (devname != NULL) { 2623 if (vn_isdisk(sp->sw_vp)) 2624 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2625 else 2626 tmp_devname = "[file]"; 2627 strncpy(devname, tmp_devname, len); 2628 } 2629 error = 0; 2630 break; 2631 } 2632 mtx_unlock(&sw_dev_mtx); 2633 return (error); 2634 } 2635 2636 #if defined(COMPAT_FREEBSD11) 2637 #define XSWDEV_VERSION_11 1 2638 struct xswdev11 { 2639 u_int xsw_version; 2640 uint32_t xsw_dev; 2641 int xsw_flags; 2642 int xsw_nblks; 2643 int xsw_used; 2644 }; 2645 #endif 2646 2647 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2648 struct xswdev32 { 2649 u_int xsw_version; 2650 u_int xsw_dev1, xsw_dev2; 2651 int xsw_flags; 2652 int xsw_nblks; 2653 int xsw_used; 2654 }; 2655 #endif 2656 2657 static int 2658 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2659 { 2660 struct xswdev xs; 2661 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2662 struct xswdev32 xs32; 2663 #endif 2664 #if defined(COMPAT_FREEBSD11) 2665 struct xswdev11 xs11; 2666 #endif 2667 int error; 2668 2669 if (arg2 != 1) /* name length */ 2670 return (EINVAL); 2671 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2672 if (error != 0) 2673 return (error); 2674 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2675 if (req->oldlen == sizeof(xs32)) { 2676 xs32.xsw_version = XSWDEV_VERSION; 2677 xs32.xsw_dev1 = xs.xsw_dev; 2678 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2679 xs32.xsw_flags = xs.xsw_flags; 2680 xs32.xsw_nblks = xs.xsw_nblks; 2681 xs32.xsw_used = xs.xsw_used; 2682 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2683 return (error); 2684 } 2685 #endif 2686 #if defined(COMPAT_FREEBSD11) 2687 if (req->oldlen == sizeof(xs11)) { 2688 xs11.xsw_version = XSWDEV_VERSION_11; 2689 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2690 xs11.xsw_flags = xs.xsw_flags; 2691 xs11.xsw_nblks = xs.xsw_nblks; 2692 xs11.xsw_used = xs.xsw_used; 2693 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2694 return (error); 2695 } 2696 #endif 2697 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2698 return (error); 2699 } 2700 2701 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2702 "Number of swap devices"); 2703 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2704 sysctl_vm_swap_info, 2705 "Swap statistics by device"); 2706 2707 /* 2708 * Count the approximate swap usage in pages for a vmspace. The 2709 * shadowed or not yet copied on write swap blocks are not accounted. 2710 * The map must be locked. 2711 */ 2712 long 2713 vmspace_swap_count(struct vmspace *vmspace) 2714 { 2715 vm_map_t map; 2716 vm_map_entry_t cur; 2717 vm_object_t object; 2718 struct swblk *sb; 2719 vm_pindex_t e, pi; 2720 long count; 2721 int i; 2722 2723 map = &vmspace->vm_map; 2724 count = 0; 2725 2726 VM_MAP_ENTRY_FOREACH(cur, map) { 2727 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2728 continue; 2729 object = cur->object.vm_object; 2730 if (object == NULL || object->type != OBJT_SWAP) 2731 continue; 2732 VM_OBJECT_RLOCK(object); 2733 if (object->type != OBJT_SWAP) 2734 goto unlock; 2735 pi = OFF_TO_IDX(cur->offset); 2736 e = pi + OFF_TO_IDX(cur->end - cur->start); 2737 for (;; pi = sb->p + SWAP_META_PAGES) { 2738 sb = SWAP_PCTRIE_LOOKUP_GE( 2739 &object->un_pager.swp.swp_blks, pi); 2740 if (sb == NULL || sb->p >= e) 2741 break; 2742 for (i = 0; i < SWAP_META_PAGES; i++) { 2743 if (sb->p + i < e && 2744 sb->d[i] != SWAPBLK_NONE) 2745 count++; 2746 } 2747 } 2748 unlock: 2749 VM_OBJECT_RUNLOCK(object); 2750 } 2751 return (count); 2752 } 2753 2754 /* 2755 * GEOM backend 2756 * 2757 * Swapping onto disk devices. 2758 * 2759 */ 2760 2761 static g_orphan_t swapgeom_orphan; 2762 2763 static struct g_class g_swap_class = { 2764 .name = "SWAP", 2765 .version = G_VERSION, 2766 .orphan = swapgeom_orphan, 2767 }; 2768 2769 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2770 2771 static void 2772 swapgeom_close_ev(void *arg, int flags) 2773 { 2774 struct g_consumer *cp; 2775 2776 cp = arg; 2777 g_access(cp, -1, -1, 0); 2778 g_detach(cp); 2779 g_destroy_consumer(cp); 2780 } 2781 2782 /* 2783 * Add a reference to the g_consumer for an inflight transaction. 2784 */ 2785 static void 2786 swapgeom_acquire(struct g_consumer *cp) 2787 { 2788 2789 mtx_assert(&sw_dev_mtx, MA_OWNED); 2790 cp->index++; 2791 } 2792 2793 /* 2794 * Remove a reference from the g_consumer. Post a close event if all 2795 * references go away, since the function might be called from the 2796 * biodone context. 2797 */ 2798 static void 2799 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2800 { 2801 2802 mtx_assert(&sw_dev_mtx, MA_OWNED); 2803 cp->index--; 2804 if (cp->index == 0) { 2805 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2806 sp->sw_id = NULL; 2807 } 2808 } 2809 2810 static void 2811 swapgeom_done(struct bio *bp2) 2812 { 2813 struct swdevt *sp; 2814 struct buf *bp; 2815 struct g_consumer *cp; 2816 2817 bp = bp2->bio_caller2; 2818 cp = bp2->bio_from; 2819 bp->b_ioflags = bp2->bio_flags; 2820 if (bp2->bio_error) 2821 bp->b_ioflags |= BIO_ERROR; 2822 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2823 bp->b_error = bp2->bio_error; 2824 bp->b_caller1 = NULL; 2825 bufdone(bp); 2826 sp = bp2->bio_caller1; 2827 mtx_lock(&sw_dev_mtx); 2828 swapgeom_release(cp, sp); 2829 mtx_unlock(&sw_dev_mtx); 2830 g_destroy_bio(bp2); 2831 } 2832 2833 static void 2834 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2835 { 2836 struct bio *bio; 2837 struct g_consumer *cp; 2838 2839 mtx_lock(&sw_dev_mtx); 2840 cp = sp->sw_id; 2841 if (cp == NULL) { 2842 mtx_unlock(&sw_dev_mtx); 2843 bp->b_error = ENXIO; 2844 bp->b_ioflags |= BIO_ERROR; 2845 bufdone(bp); 2846 return; 2847 } 2848 swapgeom_acquire(cp); 2849 mtx_unlock(&sw_dev_mtx); 2850 if (bp->b_iocmd == BIO_WRITE) 2851 bio = g_new_bio(); 2852 else 2853 bio = g_alloc_bio(); 2854 if (bio == NULL) { 2855 mtx_lock(&sw_dev_mtx); 2856 swapgeom_release(cp, sp); 2857 mtx_unlock(&sw_dev_mtx); 2858 bp->b_error = ENOMEM; 2859 bp->b_ioflags |= BIO_ERROR; 2860 printf("swap_pager: cannot allocate bio\n"); 2861 bufdone(bp); 2862 return; 2863 } 2864 2865 bp->b_caller1 = bio; 2866 bio->bio_caller1 = sp; 2867 bio->bio_caller2 = bp; 2868 bio->bio_cmd = bp->b_iocmd; 2869 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2870 bio->bio_length = bp->b_bcount; 2871 bio->bio_done = swapgeom_done; 2872 if (!buf_mapped(bp)) { 2873 bio->bio_ma = bp->b_pages; 2874 bio->bio_data = unmapped_buf; 2875 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2876 bio->bio_ma_n = bp->b_npages; 2877 bio->bio_flags |= BIO_UNMAPPED; 2878 } else { 2879 bio->bio_data = bp->b_data; 2880 bio->bio_ma = NULL; 2881 } 2882 g_io_request(bio, cp); 2883 return; 2884 } 2885 2886 static void 2887 swapgeom_orphan(struct g_consumer *cp) 2888 { 2889 struct swdevt *sp; 2890 int destroy; 2891 2892 mtx_lock(&sw_dev_mtx); 2893 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2894 if (sp->sw_id == cp) { 2895 sp->sw_flags |= SW_CLOSING; 2896 break; 2897 } 2898 } 2899 /* 2900 * Drop reference we were created with. Do directly since we're in a 2901 * special context where we don't have to queue the call to 2902 * swapgeom_close_ev(). 2903 */ 2904 cp->index--; 2905 destroy = ((sp != NULL) && (cp->index == 0)); 2906 if (destroy) 2907 sp->sw_id = NULL; 2908 mtx_unlock(&sw_dev_mtx); 2909 if (destroy) 2910 swapgeom_close_ev(cp, 0); 2911 } 2912 2913 static void 2914 swapgeom_close(struct thread *td, struct swdevt *sw) 2915 { 2916 struct g_consumer *cp; 2917 2918 mtx_lock(&sw_dev_mtx); 2919 cp = sw->sw_id; 2920 sw->sw_id = NULL; 2921 mtx_unlock(&sw_dev_mtx); 2922 2923 /* 2924 * swapgeom_close() may be called from the biodone context, 2925 * where we cannot perform topology changes. Delegate the 2926 * work to the events thread. 2927 */ 2928 if (cp != NULL) 2929 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2930 } 2931 2932 static int 2933 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2934 { 2935 struct g_provider *pp; 2936 struct g_consumer *cp; 2937 static struct g_geom *gp; 2938 struct swdevt *sp; 2939 u_long nblks; 2940 int error; 2941 2942 pp = g_dev_getprovider(dev); 2943 if (pp == NULL) 2944 return (ENODEV); 2945 mtx_lock(&sw_dev_mtx); 2946 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2947 cp = sp->sw_id; 2948 if (cp != NULL && cp->provider == pp) { 2949 mtx_unlock(&sw_dev_mtx); 2950 return (EBUSY); 2951 } 2952 } 2953 mtx_unlock(&sw_dev_mtx); 2954 if (gp == NULL) 2955 gp = g_new_geomf(&g_swap_class, "swap"); 2956 cp = g_new_consumer(gp); 2957 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2958 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2959 g_attach(cp, pp); 2960 /* 2961 * XXX: Every time you think you can improve the margin for 2962 * footshooting, somebody depends on the ability to do so: 2963 * savecore(8) wants to write to our swapdev so we cannot 2964 * set an exclusive count :-( 2965 */ 2966 error = g_access(cp, 1, 1, 0); 2967 if (error != 0) { 2968 g_detach(cp); 2969 g_destroy_consumer(cp); 2970 return (error); 2971 } 2972 nblks = pp->mediasize / DEV_BSIZE; 2973 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2974 swapgeom_close, dev2udev(dev), 2975 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2976 return (0); 2977 } 2978 2979 static int 2980 swapongeom(struct vnode *vp) 2981 { 2982 int error; 2983 2984 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2985 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 2986 error = ENOENT; 2987 } else { 2988 g_topology_lock(); 2989 error = swapongeom_locked(vp->v_rdev, vp); 2990 g_topology_unlock(); 2991 } 2992 VOP_UNLOCK(vp); 2993 return (error); 2994 } 2995 2996 /* 2997 * VNODE backend 2998 * 2999 * This is used mainly for network filesystem (read: probably only tested 3000 * with NFS) swapfiles. 3001 * 3002 */ 3003 3004 static void 3005 swapdev_strategy(struct buf *bp, struct swdevt *sp) 3006 { 3007 struct vnode *vp2; 3008 3009 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 3010 3011 vp2 = sp->sw_id; 3012 vhold(vp2); 3013 if (bp->b_iocmd == BIO_WRITE) { 3014 if (bp->b_bufobj) 3015 bufobj_wdrop(bp->b_bufobj); 3016 bufobj_wref(&vp2->v_bufobj); 3017 } 3018 if (bp->b_bufobj != &vp2->v_bufobj) 3019 bp->b_bufobj = &vp2->v_bufobj; 3020 bp->b_vp = vp2; 3021 bp->b_iooffset = dbtob(bp->b_blkno); 3022 bstrategy(bp); 3023 return; 3024 } 3025 3026 static void 3027 swapdev_close(struct thread *td, struct swdevt *sp) 3028 { 3029 3030 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 3031 vrele(sp->sw_vp); 3032 } 3033 3034 static int 3035 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3036 { 3037 struct swdevt *sp; 3038 int error; 3039 3040 if (nblks == 0) 3041 return (ENXIO); 3042 mtx_lock(&sw_dev_mtx); 3043 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3044 if (sp->sw_id == vp) { 3045 mtx_unlock(&sw_dev_mtx); 3046 return (EBUSY); 3047 } 3048 } 3049 mtx_unlock(&sw_dev_mtx); 3050 3051 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3052 #ifdef MAC 3053 error = mac_system_check_swapon(td->td_ucred, vp); 3054 if (error == 0) 3055 #endif 3056 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3057 (void) VOP_UNLOCK(vp); 3058 if (error) 3059 return (error); 3060 3061 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3062 NODEV, 0); 3063 return (0); 3064 } 3065 3066 static int 3067 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3068 { 3069 int error, new, n; 3070 3071 new = nsw_wcount_async_max; 3072 error = sysctl_handle_int(oidp, &new, 0, req); 3073 if (error != 0 || req->newptr == NULL) 3074 return (error); 3075 3076 if (new > nswbuf / 2 || new < 1) 3077 return (EINVAL); 3078 3079 mtx_lock(&swbuf_mtx); 3080 while (nsw_wcount_async_max != new) { 3081 /* 3082 * Adjust difference. If the current async count is too low, 3083 * we will need to sqeeze our update slowly in. Sleep with a 3084 * higher priority than getpbuf() to finish faster. 3085 */ 3086 n = new - nsw_wcount_async_max; 3087 if (nsw_wcount_async + n >= 0) { 3088 nsw_wcount_async += n; 3089 nsw_wcount_async_max += n; 3090 wakeup(&nsw_wcount_async); 3091 } else { 3092 nsw_wcount_async_max -= nsw_wcount_async; 3093 nsw_wcount_async = 0; 3094 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3095 "swpsysctl", 0); 3096 } 3097 } 3098 mtx_unlock(&swbuf_mtx); 3099 3100 return (0); 3101 } 3102 3103 static void 3104 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3105 vm_offset_t end) 3106 { 3107 3108 VM_OBJECT_WLOCK(object); 3109 KASSERT((object->flags & OBJ_ANON) == 0, 3110 ("Splittable object with writecount")); 3111 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3112 VM_OBJECT_WUNLOCK(object); 3113 } 3114 3115 static void 3116 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3117 vm_offset_t end) 3118 { 3119 3120 VM_OBJECT_WLOCK(object); 3121 KASSERT((object->flags & OBJ_ANON) == 0, 3122 ("Splittable object with writecount")); 3123 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3124 VM_OBJECT_WUNLOCK(object); 3125 } 3126