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/limits.h> 86 #include <sys/lock.h> 87 #include <sys/kernel.h> 88 #include <sys/mount.h> 89 #include <sys/namei.h> 90 #include <sys/malloc.h> 91 #include <sys/pctrie.h> 92 #include <sys/priv.h> 93 #include <sys/proc.h> 94 #include <sys/racct.h> 95 #include <sys/resource.h> 96 #include <sys/resourcevar.h> 97 #include <sys/rwlock.h> 98 #include <sys/sbuf.h> 99 #include <sys/sysctl.h> 100 #include <sys/sysproto.h> 101 #include <sys/systm.h> 102 #include <sys/sx.h> 103 #include <sys/unistd.h> 104 #include <sys/user.h> 105 #include <sys/vmmeter.h> 106 #include <sys/vnode.h> 107 108 #include <security/mac/mac_framework.h> 109 110 #include <vm/vm.h> 111 #include <vm/pmap.h> 112 #include <vm/vm_map.h> 113 #include <vm/vm_kern.h> 114 #include <vm/vm_object.h> 115 #include <vm/vm_page.h> 116 #include <vm/vm_pager.h> 117 #include <vm/vm_pageout.h> 118 #include <vm/vm_param.h> 119 #include <vm/swap_pager.h> 120 #include <vm/vm_extern.h> 121 #include <vm/uma.h> 122 123 #include <geom/geom.h> 124 125 /* 126 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 127 * The 64-page limit is due to the radix code (kern/subr_blist.c). 128 */ 129 #ifndef MAX_PAGEOUT_CLUSTER 130 #define MAX_PAGEOUT_CLUSTER 32 131 #endif 132 133 #if !defined(SWB_NPAGES) 134 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 135 #endif 136 137 #define SWAP_META_PAGES PCTRIE_COUNT 138 139 /* 140 * A swblk structure maps each page index within a 141 * SWAP_META_PAGES-aligned and sized range to the address of an 142 * on-disk swap block (or SWAPBLK_NONE). The collection of these 143 * mappings for an entire vm object is implemented as a pc-trie. 144 */ 145 struct swblk { 146 vm_pindex_t p; 147 daddr_t d[SWAP_META_PAGES]; 148 }; 149 150 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 151 static struct mtx sw_dev_mtx; 152 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 153 static struct swdevt *swdevhd; /* Allocate from here next */ 154 static int nswapdev; /* Number of swap devices */ 155 int swap_pager_avail; 156 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 157 158 static __exclusive_cache_line u_long swap_reserved; 159 static u_long swap_total; 160 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 161 162 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 163 "VM swap stats"); 164 165 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 166 &swap_reserved, 0, sysctl_page_shift, "A", 167 "Amount of swap storage needed to back all allocated anonymous memory."); 168 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 169 &swap_total, 0, sysctl_page_shift, "A", 170 "Total amount of available swap storage."); 171 172 static int overcommit = 0; 173 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 174 "Configure virtual memory overcommit behavior. See tuning(7) " 175 "for details."); 176 static unsigned long swzone; 177 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 178 "Actual size of swap metadata zone"); 179 static unsigned long swap_maxpages; 180 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 181 "Maximum amount of swap supported"); 182 183 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); 184 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 185 CTLFLAG_RD, &swap_free_deferred, 186 "Number of pages that deferred freeing swap space"); 187 188 static COUNTER_U64_DEFINE_EARLY(swap_free_completed); 189 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 190 CTLFLAG_RD, &swap_free_completed, 191 "Number of deferred frees completed"); 192 193 /* bits from overcommit */ 194 #define SWAP_RESERVE_FORCE_ON (1 << 0) 195 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 196 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 197 198 static int 199 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 200 { 201 uint64_t newval; 202 u_long value = *(u_long *)arg1; 203 204 newval = ((uint64_t)value) << PAGE_SHIFT; 205 return (sysctl_handle_64(oidp, &newval, 0, req)); 206 } 207 208 static bool 209 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) 210 { 211 struct uidinfo *uip; 212 u_long prev; 213 214 uip = cred->cr_ruidinfo; 215 216 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 217 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && 218 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 219 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { 220 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 221 KASSERT(prev >= pincr, ("negative vmsize for uid = %d\n", uip->ui_uid)); 222 return (false); 223 } 224 return (true); 225 } 226 227 static void 228 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) 229 { 230 struct uidinfo *uip; 231 #ifdef INVARIANTS 232 u_long prev; 233 #endif 234 235 uip = cred->cr_ruidinfo; 236 237 #ifdef INVARIANTS 238 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 239 KASSERT(prev >= pdecr, ("negative vmsize for uid = %d\n", uip->ui_uid)); 240 #else 241 atomic_subtract_long(&uip->ui_vmsize, pdecr); 242 #endif 243 } 244 245 static void 246 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) 247 { 248 struct uidinfo *uip; 249 250 uip = cred->cr_ruidinfo; 251 atomic_add_long(&uip->ui_vmsize, pincr); 252 } 253 254 bool 255 swap_reserve(vm_ooffset_t incr) 256 { 257 258 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 259 } 260 261 bool 262 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 263 { 264 u_long r, s, prev, pincr; 265 #ifdef RACCT 266 int error; 267 #endif 268 int oc; 269 static int curfail; 270 static struct timeval lastfail; 271 272 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 273 (uintmax_t)incr)); 274 275 #ifdef RACCT 276 if (RACCT_ENABLED()) { 277 PROC_LOCK(curproc); 278 error = racct_add(curproc, RACCT_SWAP, incr); 279 PROC_UNLOCK(curproc); 280 if (error != 0) 281 return (false); 282 } 283 #endif 284 285 pincr = atop(incr); 286 prev = atomic_fetchadd_long(&swap_reserved, pincr); 287 r = prev + pincr; 288 s = swap_total; 289 oc = atomic_load_int(&overcommit); 290 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { 291 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - 292 vm_wire_count(); 293 } 294 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && 295 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { 296 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 297 KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); 298 goto out_error; 299 } 300 301 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { 302 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 303 KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); 304 goto out_error; 305 } 306 307 return (true); 308 309 out_error: 310 if (ppsratecheck(&lastfail, &curfail, 1)) { 311 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 312 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); 313 } 314 #ifdef RACCT 315 if (RACCT_ENABLED()) { 316 PROC_LOCK(curproc); 317 racct_sub(curproc, RACCT_SWAP, incr); 318 PROC_UNLOCK(curproc); 319 } 320 #endif 321 322 return (false); 323 } 324 325 void 326 swap_reserve_force(vm_ooffset_t incr) 327 { 328 u_long pincr; 329 330 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 331 (uintmax_t)incr)); 332 333 #ifdef RACCT 334 if (RACCT_ENABLED()) { 335 PROC_LOCK(curproc); 336 racct_add_force(curproc, RACCT_SWAP, incr); 337 PROC_UNLOCK(curproc); 338 } 339 #endif 340 pincr = atop(incr); 341 atomic_add_long(&swap_reserved, pincr); 342 swap_reserve_force_rlimit(pincr, curthread->td_ucred); 343 } 344 345 void 346 swap_release(vm_ooffset_t decr) 347 { 348 struct ucred *cred; 349 350 PROC_LOCK(curproc); 351 cred = curproc->p_ucred; 352 swap_release_by_cred(decr, cred); 353 PROC_UNLOCK(curproc); 354 } 355 356 void 357 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 358 { 359 u_long pdecr; 360 #ifdef INVARIANTS 361 u_long prev; 362 #endif 363 364 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 365 (uintmax_t)decr)); 366 367 pdecr = atop(decr); 368 #ifdef INVARIANTS 369 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 370 KASSERT(prev >= pdecr, ("swap_reserved < decr")); 371 #else 372 atomic_subtract_long(&swap_reserved, pdecr); 373 #endif 374 375 swap_release_by_cred_rlimit(pdecr, cred); 376 #ifdef RACCT 377 if (racct_enable) 378 racct_sub_cred(cred, RACCT_SWAP, decr); 379 #endif 380 } 381 382 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 383 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 384 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 385 static int nsw_wcount_async; /* limit async write buffers */ 386 static int nsw_wcount_async_max;/* assigned maximum */ 387 int nsw_cluster_max; /* maximum VOP I/O allowed */ 388 389 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 390 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 391 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 392 "Maximum running async swap ops"); 393 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 394 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 395 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 396 "Swap Fragmentation Info"); 397 398 static struct sx sw_alloc_sx; 399 400 /* 401 * "named" and "unnamed" anon region objects. Try to reduce the overhead 402 * of searching a named list by hashing it just a little. 403 */ 404 405 #define NOBJLISTS 8 406 407 #define NOBJLIST(handle) \ 408 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 409 410 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 411 static uma_zone_t swwbuf_zone; 412 static uma_zone_t swrbuf_zone; 413 static uma_zone_t swblk_zone; 414 static uma_zone_t swpctrie_zone; 415 416 /* 417 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 418 * calls hooked from other parts of the VM system and do not appear here. 419 * (see vm/swap_pager.h). 420 */ 421 static vm_object_t 422 swap_pager_alloc(void *handle, vm_ooffset_t size, 423 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 424 static void swap_pager_dealloc(vm_object_t object); 425 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 426 int *); 427 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 428 int *, pgo_getpages_iodone_t, void *); 429 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 430 static boolean_t 431 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 432 static void swap_pager_init(void); 433 static void swap_pager_unswapped(vm_page_t); 434 static void swap_pager_swapoff(struct swdevt *sp); 435 static void swap_pager_update_writecount(vm_object_t object, 436 vm_offset_t start, vm_offset_t end); 437 static void swap_pager_release_writecount(vm_object_t object, 438 vm_offset_t start, vm_offset_t end); 439 static void swap_pager_freespace(vm_object_t object, vm_pindex_t start, 440 vm_size_t size); 441 442 const struct pagerops swappagerops = { 443 .pgo_kvme_type = KVME_TYPE_SWAP, 444 .pgo_init = swap_pager_init, /* early system initialization of pager */ 445 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 446 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 447 .pgo_getpages = swap_pager_getpages, /* pagein */ 448 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 449 .pgo_putpages = swap_pager_putpages, /* pageout */ 450 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 451 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 452 .pgo_update_writecount = swap_pager_update_writecount, 453 .pgo_release_writecount = swap_pager_release_writecount, 454 .pgo_freespace = swap_pager_freespace, 455 }; 456 457 /* 458 * swap_*() routines are externally accessible. swp_*() routines are 459 * internal. 460 */ 461 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 462 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 463 464 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 465 "Maximum size of a swap block in pages"); 466 467 static void swp_sizecheck(void); 468 static void swp_pager_async_iodone(struct buf *bp); 469 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 470 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 471 static int swapongeom(struct vnode *); 472 static int swaponvp(struct thread *, struct vnode *, u_long); 473 static int swapoff_one(struct swdevt *sp, struct ucred *cred, 474 u_int flags); 475 476 /* 477 * Swap bitmap functions 478 */ 479 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 480 static daddr_t swp_pager_getswapspace(int *npages); 481 482 /* 483 * Metadata functions 484 */ 485 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 486 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 487 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 488 vm_pindex_t pindex, vm_pindex_t count); 489 static void swp_pager_meta_free_all(vm_object_t); 490 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 491 492 static void 493 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 494 { 495 496 *start = SWAPBLK_NONE; 497 *num = 0; 498 } 499 500 static void 501 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 502 { 503 504 if (*start + *num == addr) { 505 (*num)++; 506 } else { 507 swp_pager_freeswapspace(*start, *num); 508 *start = addr; 509 *num = 1; 510 } 511 } 512 513 static void * 514 swblk_trie_alloc(struct pctrie *ptree) 515 { 516 517 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 518 M_USE_RESERVE : 0))); 519 } 520 521 static void 522 swblk_trie_free(struct pctrie *ptree, void *node) 523 { 524 525 uma_zfree(swpctrie_zone, node); 526 } 527 528 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 529 530 /* 531 * SWP_SIZECHECK() - update swap_pager_full indication 532 * 533 * update the swap_pager_almost_full indication and warn when we are 534 * about to run out of swap space, using lowat/hiwat hysteresis. 535 * 536 * Clear swap_pager_full ( task killing ) indication when lowat is met. 537 * 538 * No restrictions on call 539 * This routine may not block. 540 */ 541 static void 542 swp_sizecheck(void) 543 { 544 545 if (swap_pager_avail < nswap_lowat) { 546 if (swap_pager_almost_full == 0) { 547 printf("swap_pager: out of swap space\n"); 548 swap_pager_almost_full = 1; 549 } 550 } else { 551 swap_pager_full = 0; 552 if (swap_pager_avail > nswap_hiwat) 553 swap_pager_almost_full = 0; 554 } 555 } 556 557 /* 558 * SWAP_PAGER_INIT() - initialize the swap pager! 559 * 560 * Expected to be started from system init. NOTE: This code is run 561 * before much else so be careful what you depend on. Most of the VM 562 * system has yet to be initialized at this point. 563 */ 564 static void 565 swap_pager_init(void) 566 { 567 /* 568 * Initialize object lists 569 */ 570 int i; 571 572 for (i = 0; i < NOBJLISTS; ++i) 573 TAILQ_INIT(&swap_pager_object_list[i]); 574 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 575 sx_init(&sw_alloc_sx, "swspsx"); 576 sx_init(&swdev_syscall_lock, "swsysc"); 577 578 /* 579 * The nsw_cluster_max is constrained by the bp->b_pages[] 580 * array, which has maxphys / PAGE_SIZE entries, and our locally 581 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 582 * constrained by the swap device interleave stripe size. 583 * 584 * Initialized early so that GEOM_ELI can see it. 585 */ 586 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 587 } 588 589 /* 590 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 591 * 592 * Expected to be started from pageout process once, prior to entering 593 * its main loop. 594 */ 595 void 596 swap_pager_swap_init(void) 597 { 598 unsigned long n, n2; 599 600 /* 601 * Number of in-transit swap bp operations. Don't 602 * exhaust the pbufs completely. Make sure we 603 * initialize workable values (0 will work for hysteresis 604 * but it isn't very efficient). 605 * 606 * Currently we hardwire nsw_wcount_async to 4. This limit is 607 * designed to prevent other I/O from having high latencies due to 608 * our pageout I/O. The value 4 works well for one or two active swap 609 * devices but is probably a little low if you have more. Even so, 610 * a higher value would probably generate only a limited improvement 611 * with three or four active swap devices since the system does not 612 * typically have to pageout at extreme bandwidths. We will want 613 * at least 2 per swap devices, and 4 is a pretty good value if you 614 * have one NFS swap device due to the command/ack latency over NFS. 615 * So it all works out pretty well. 616 * 617 * nsw_cluster_max is initialized in swap_pager_init(). 618 */ 619 620 nsw_wcount_async = 4; 621 nsw_wcount_async_max = nsw_wcount_async; 622 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 623 624 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 625 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 626 627 /* 628 * Initialize our zone, taking the user's requested size or 629 * estimating the number we need based on the number of pages 630 * in the system. 631 */ 632 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 633 vm_cnt.v_page_count / 2; 634 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 635 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 636 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 637 NULL, NULL, _Alignof(struct swblk) - 1, 0); 638 n2 = n; 639 do { 640 if (uma_zone_reserve_kva(swblk_zone, n)) 641 break; 642 /* 643 * if the allocation failed, try a zone two thirds the 644 * size of the previous attempt. 645 */ 646 n -= ((n + 2) / 3); 647 } while (n > 0); 648 649 /* 650 * Often uma_zone_reserve_kva() cannot reserve exactly the 651 * requested size. Account for the difference when 652 * calculating swap_maxpages. 653 */ 654 n = uma_zone_get_max(swblk_zone); 655 656 if (n < n2) 657 printf("Swap blk zone entries changed from %lu to %lu.\n", 658 n2, n); 659 /* absolute maximum we can handle assuming 100% efficiency */ 660 swap_maxpages = n * SWAP_META_PAGES; 661 swzone = n * sizeof(struct swblk); 662 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 663 printf("Cannot reserve swap pctrie zone, " 664 "reduce kern.maxswzone.\n"); 665 } 666 667 bool 668 swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, 669 vm_ooffset_t size, vm_ooffset_t offset) 670 { 671 if (cred != NULL) { 672 if (!swap_reserve_by_cred(size, cred)) 673 return (false); 674 crhold(cred); 675 } 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 (true); 684 } 685 686 static vm_object_t 687 swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred, 688 vm_ooffset_t size, vm_ooffset_t offset) 689 { 690 vm_object_t object; 691 692 /* 693 * The un_pager.swp.swp_blks trie is initialized by 694 * vm_object_allocate() to ensure the correct order of 695 * visibility to other threads. 696 */ 697 object = vm_object_allocate(otype, OFF_TO_IDX(offset + 698 PAGE_MASK + size)); 699 700 if (!swap_pager_init_object(object, handle, cred, size, offset)) { 701 vm_object_deallocate(object); 702 return (NULL); 703 } 704 return (object); 705 } 706 707 /* 708 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 709 * its metadata structures. 710 * 711 * This routine is called from the mmap and fork code to create a new 712 * OBJT_SWAP object. 713 * 714 * This routine must ensure that no live duplicate is created for 715 * the named object request, which is protected against by 716 * holding the sw_alloc_sx lock in case handle != NULL. 717 */ 718 static vm_object_t 719 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 720 vm_ooffset_t offset, struct ucred *cred) 721 { 722 vm_object_t object; 723 724 if (handle != NULL) { 725 /* 726 * Reference existing named region or allocate new one. There 727 * should not be a race here against swp_pager_meta_build() 728 * as called from vm_page_remove() in regards to the lookup 729 * of the handle. 730 */ 731 sx_xlock(&sw_alloc_sx); 732 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 733 if (object == NULL) { 734 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 735 size, offset); 736 if (object != NULL) { 737 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 738 object, pager_object_list); 739 } 740 } 741 sx_xunlock(&sw_alloc_sx); 742 } else { 743 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 744 size, offset); 745 } 746 return (object); 747 } 748 749 /* 750 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 751 * 752 * The swap backing for the object is destroyed. The code is 753 * designed such that we can reinstantiate it later, but this 754 * routine is typically called only when the entire object is 755 * about to be destroyed. 756 * 757 * The object must be locked. 758 */ 759 static void 760 swap_pager_dealloc(vm_object_t object) 761 { 762 763 VM_OBJECT_ASSERT_WLOCKED(object); 764 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 765 766 /* 767 * Remove from list right away so lookups will fail if we block for 768 * pageout completion. 769 */ 770 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 771 VM_OBJECT_WUNLOCK(object); 772 sx_xlock(&sw_alloc_sx); 773 TAILQ_REMOVE(NOBJLIST(object->handle), object, 774 pager_object_list); 775 sx_xunlock(&sw_alloc_sx); 776 VM_OBJECT_WLOCK(object); 777 } 778 779 vm_object_pip_wait(object, "swpdea"); 780 781 /* 782 * Free all remaining metadata. We only bother to free it from 783 * the swap meta data. We do not attempt to free swapblk's still 784 * associated with vm_page_t's for this object. We do not care 785 * if paging is still in progress on some objects. 786 */ 787 swp_pager_meta_free_all(object); 788 object->handle = NULL; 789 object->type = OBJT_DEAD; 790 vm_object_clear_flag(object, OBJ_SWAP); 791 } 792 793 /************************************************************************ 794 * SWAP PAGER BITMAP ROUTINES * 795 ************************************************************************/ 796 797 /* 798 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 799 * 800 * Allocate swap for up to the requested number of pages. The 801 * starting swap block number (a page index) is returned or 802 * SWAPBLK_NONE if the allocation failed. 803 * 804 * Also has the side effect of advising that somebody made a mistake 805 * when they configured swap and didn't configure enough. 806 * 807 * This routine may not sleep. 808 * 809 * We allocate in round-robin fashion from the configured devices. 810 */ 811 static daddr_t 812 swp_pager_getswapspace(int *io_npages) 813 { 814 daddr_t blk; 815 struct swdevt *sp; 816 int mpages, npages; 817 818 KASSERT(*io_npages >= 1, 819 ("%s: npages not positive", __func__)); 820 blk = SWAPBLK_NONE; 821 mpages = *io_npages; 822 npages = imin(BLIST_MAX_ALLOC, mpages); 823 mtx_lock(&sw_dev_mtx); 824 sp = swdevhd; 825 while (!TAILQ_EMPTY(&swtailq)) { 826 if (sp == NULL) 827 sp = TAILQ_FIRST(&swtailq); 828 if ((sp->sw_flags & SW_CLOSING) == 0) 829 blk = blist_alloc(sp->sw_blist, &npages, mpages); 830 if (blk != SWAPBLK_NONE) 831 break; 832 sp = TAILQ_NEXT(sp, sw_list); 833 if (swdevhd == sp) { 834 if (npages == 1) 835 break; 836 mpages = npages - 1; 837 npages >>= 1; 838 } 839 } 840 if (blk != SWAPBLK_NONE) { 841 *io_npages = npages; 842 blk += sp->sw_first; 843 sp->sw_used += npages; 844 swap_pager_avail -= npages; 845 swp_sizecheck(); 846 swdevhd = TAILQ_NEXT(sp, sw_list); 847 } else { 848 if (swap_pager_full != 2) { 849 printf("swp_pager_getswapspace(%d): failed\n", 850 *io_npages); 851 swap_pager_full = 2; 852 swap_pager_almost_full = 1; 853 } 854 swdevhd = NULL; 855 } 856 mtx_unlock(&sw_dev_mtx); 857 return (blk); 858 } 859 860 static bool 861 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 862 { 863 864 return (blk >= sp->sw_first && blk < sp->sw_end); 865 } 866 867 static void 868 swp_pager_strategy(struct buf *bp) 869 { 870 struct swdevt *sp; 871 872 mtx_lock(&sw_dev_mtx); 873 TAILQ_FOREACH(sp, &swtailq, sw_list) { 874 if (swp_pager_isondev(bp->b_blkno, sp)) { 875 mtx_unlock(&sw_dev_mtx); 876 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 877 unmapped_buf_allowed) { 878 bp->b_data = unmapped_buf; 879 bp->b_offset = 0; 880 } else { 881 pmap_qenter((vm_offset_t)bp->b_data, 882 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 883 } 884 sp->sw_strategy(bp, sp); 885 return; 886 } 887 } 888 panic("Swapdev not found"); 889 } 890 891 /* 892 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 893 * 894 * This routine returns the specified swap blocks back to the bitmap. 895 * 896 * This routine may not sleep. 897 */ 898 static void 899 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 900 { 901 struct swdevt *sp; 902 903 if (npages == 0) 904 return; 905 mtx_lock(&sw_dev_mtx); 906 TAILQ_FOREACH(sp, &swtailq, sw_list) { 907 if (swp_pager_isondev(blk, sp)) { 908 sp->sw_used -= npages; 909 /* 910 * If we are attempting to stop swapping on 911 * this device, we don't want to mark any 912 * blocks free lest they be reused. 913 */ 914 if ((sp->sw_flags & SW_CLOSING) == 0) { 915 blist_free(sp->sw_blist, blk - sp->sw_first, 916 npages); 917 swap_pager_avail += npages; 918 swp_sizecheck(); 919 } 920 mtx_unlock(&sw_dev_mtx); 921 return; 922 } 923 } 924 panic("Swapdev not found"); 925 } 926 927 /* 928 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 929 */ 930 static int 931 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 932 { 933 struct sbuf sbuf; 934 struct swdevt *sp; 935 const char *devname; 936 int error; 937 938 error = sysctl_wire_old_buffer(req, 0); 939 if (error != 0) 940 return (error); 941 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 942 mtx_lock(&sw_dev_mtx); 943 TAILQ_FOREACH(sp, &swtailq, sw_list) { 944 if (vn_isdisk(sp->sw_vp)) 945 devname = devtoname(sp->sw_vp->v_rdev); 946 else 947 devname = "[file]"; 948 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 949 blist_stats(sp->sw_blist, &sbuf); 950 } 951 mtx_unlock(&sw_dev_mtx); 952 error = sbuf_finish(&sbuf); 953 sbuf_delete(&sbuf); 954 return (error); 955 } 956 957 /* 958 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 959 * range within an object. 960 * 961 * This routine removes swapblk assignments from swap metadata. 962 * 963 * The external callers of this routine typically have already destroyed 964 * or renamed vm_page_t's associated with this range in the object so 965 * we should be ok. 966 * 967 * The object must be locked. 968 */ 969 static void 970 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 971 { 972 973 swp_pager_meta_free(object, start, size); 974 } 975 976 /* 977 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 978 * 979 * Assigns swap blocks to the specified range within the object. The 980 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 981 * 982 * Returns 0 on success, -1 on failure. 983 */ 984 int 985 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 986 { 987 daddr_t addr, blk, n_free, s_free; 988 vm_pindex_t i, j; 989 int n; 990 991 swp_pager_init_freerange(&s_free, &n_free); 992 VM_OBJECT_WLOCK(object); 993 for (i = 0; i < size; i += n) { 994 n = MIN(size - i, INT_MAX); 995 blk = swp_pager_getswapspace(&n); 996 if (blk == SWAPBLK_NONE) { 997 swp_pager_meta_free(object, start, i); 998 VM_OBJECT_WUNLOCK(object); 999 return (-1); 1000 } 1001 for (j = 0; j < n; ++j) { 1002 addr = swp_pager_meta_build(object, 1003 start + i + j, blk + j); 1004 if (addr != SWAPBLK_NONE) 1005 swp_pager_update_freerange(&s_free, &n_free, 1006 addr); 1007 } 1008 } 1009 swp_pager_freeswapspace(s_free, n_free); 1010 VM_OBJECT_WUNLOCK(object); 1011 return (0); 1012 } 1013 1014 static bool 1015 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 1016 vm_pindex_t pindex, daddr_t addr) 1017 { 1018 daddr_t dstaddr; 1019 1020 KASSERT((srcobject->flags & OBJ_SWAP) != 0, 1021 ("%s: Srcobject not swappable", __func__)); 1022 if ((dstobject->flags & OBJ_SWAP) != 0 && 1023 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 1024 /* Caller should destroy the source block. */ 1025 return (false); 1026 } 1027 1028 /* 1029 * Destination has no swapblk and is not resident, transfer source. 1030 * swp_pager_meta_build() can sleep. 1031 */ 1032 VM_OBJECT_WUNLOCK(srcobject); 1033 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 1034 KASSERT(dstaddr == SWAPBLK_NONE, 1035 ("Unexpected destination swapblk")); 1036 VM_OBJECT_WLOCK(srcobject); 1037 1038 return (true); 1039 } 1040 1041 /* 1042 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 1043 * and destroy the source. 1044 * 1045 * Copy any valid swapblks from the source to the destination. In 1046 * cases where both the source and destination have a valid swapblk, 1047 * we keep the destination's. 1048 * 1049 * This routine is allowed to sleep. It may sleep allocating metadata 1050 * indirectly through swp_pager_meta_build(). 1051 * 1052 * The source object contains no vm_page_t's (which is just as well) 1053 * 1054 * The source object is of type OBJT_SWAP. 1055 * 1056 * The source and destination objects must be locked. 1057 * Both object locks may temporarily be released. 1058 */ 1059 void 1060 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1061 vm_pindex_t offset, int destroysource) 1062 { 1063 1064 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1065 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1066 1067 /* 1068 * If destroysource is set, we remove the source object from the 1069 * swap_pager internal queue now. 1070 */ 1071 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1072 srcobject->handle != NULL) { 1073 VM_OBJECT_WUNLOCK(srcobject); 1074 VM_OBJECT_WUNLOCK(dstobject); 1075 sx_xlock(&sw_alloc_sx); 1076 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1077 pager_object_list); 1078 sx_xunlock(&sw_alloc_sx); 1079 VM_OBJECT_WLOCK(dstobject); 1080 VM_OBJECT_WLOCK(srcobject); 1081 } 1082 1083 /* 1084 * Transfer source to destination. 1085 */ 1086 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1087 1088 /* 1089 * Free left over swap blocks in source. 1090 * 1091 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1092 * double-remove the object from the swap queues. 1093 */ 1094 if (destroysource) { 1095 swp_pager_meta_free_all(srcobject); 1096 /* 1097 * Reverting the type is not necessary, the caller is going 1098 * to destroy srcobject directly, but I'm doing it here 1099 * for consistency since we've removed the object from its 1100 * queues. 1101 */ 1102 srcobject->type = OBJT_DEFAULT; 1103 vm_object_clear_flag(srcobject, OBJ_SWAP); 1104 } 1105 } 1106 1107 /* 1108 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1109 * the requested page. 1110 * 1111 * We determine whether good backing store exists for the requested 1112 * page and return TRUE if it does, FALSE if it doesn't. 1113 * 1114 * If TRUE, we also try to determine how much valid, contiguous backing 1115 * store exists before and after the requested page. 1116 */ 1117 static boolean_t 1118 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1119 int *after) 1120 { 1121 daddr_t blk, blk0; 1122 int i; 1123 1124 VM_OBJECT_ASSERT_LOCKED(object); 1125 KASSERT((object->flags & OBJ_SWAP) != 0, 1126 ("%s: object not swappable", __func__)); 1127 1128 /* 1129 * do we have good backing store at the requested index ? 1130 */ 1131 blk0 = swp_pager_meta_lookup(object, pindex); 1132 if (blk0 == SWAPBLK_NONE) { 1133 if (before) 1134 *before = 0; 1135 if (after) 1136 *after = 0; 1137 return (FALSE); 1138 } 1139 1140 /* 1141 * find backwards-looking contiguous good backing store 1142 */ 1143 if (before != NULL) { 1144 for (i = 1; i < SWB_NPAGES; i++) { 1145 if (i > pindex) 1146 break; 1147 blk = swp_pager_meta_lookup(object, pindex - i); 1148 if (blk != blk0 - i) 1149 break; 1150 } 1151 *before = i - 1; 1152 } 1153 1154 /* 1155 * find forward-looking contiguous good backing store 1156 */ 1157 if (after != NULL) { 1158 for (i = 1; i < SWB_NPAGES; i++) { 1159 blk = swp_pager_meta_lookup(object, pindex + i); 1160 if (blk != blk0 + i) 1161 break; 1162 } 1163 *after = i - 1; 1164 } 1165 return (TRUE); 1166 } 1167 1168 /* 1169 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1170 * 1171 * This removes any associated swap backing store, whether valid or 1172 * not, from the page. 1173 * 1174 * This routine is typically called when a page is made dirty, at 1175 * which point any associated swap can be freed. MADV_FREE also 1176 * calls us in a special-case situation 1177 * 1178 * NOTE!!! If the page is clean and the swap was valid, the caller 1179 * should make the page dirty before calling this routine. This routine 1180 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1181 * depends on it. 1182 * 1183 * This routine may not sleep. 1184 * 1185 * The object containing the page may be locked. 1186 */ 1187 static void 1188 swap_pager_unswapped(vm_page_t m) 1189 { 1190 struct swblk *sb; 1191 vm_object_t obj; 1192 1193 /* 1194 * Handle enqueing deferred frees first. If we do not have the 1195 * object lock we wait for the page daemon to clear the space. 1196 */ 1197 obj = m->object; 1198 if (!VM_OBJECT_WOWNED(obj)) { 1199 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1200 /* 1201 * The caller is responsible for synchronization but we 1202 * will harmlessly handle races. This is typically provided 1203 * by only calling unswapped() when a page transitions from 1204 * clean to dirty. 1205 */ 1206 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1207 PGA_SWAP_SPACE) { 1208 vm_page_aflag_set(m, PGA_SWAP_FREE); 1209 counter_u64_add(swap_free_deferred, 1); 1210 } 1211 return; 1212 } 1213 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1214 counter_u64_add(swap_free_completed, 1); 1215 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1216 1217 /* 1218 * The meta data only exists if the object is OBJT_SWAP 1219 * and even then might not be allocated yet. 1220 */ 1221 KASSERT((m->object->flags & OBJ_SWAP) != 0, 1222 ("Free object not swappable")); 1223 1224 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1225 rounddown(m->pindex, SWAP_META_PAGES)); 1226 if (sb == NULL) 1227 return; 1228 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1229 return; 1230 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1231 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1232 swp_pager_free_empty_swblk(m->object, sb); 1233 } 1234 1235 /* 1236 * swap_pager_getpages() - bring pages in from swap 1237 * 1238 * Attempt to page in the pages in array "ma" of length "count". The 1239 * caller may optionally specify that additional pages preceding and 1240 * succeeding the specified range be paged in. The number of such pages 1241 * is returned in the "rbehind" and "rahead" parameters, and they will 1242 * be in the inactive queue upon return. 1243 * 1244 * The pages in "ma" must be busied and will remain busied upon return. 1245 */ 1246 static int 1247 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1248 int *rbehind, int *rahead) 1249 { 1250 struct buf *bp; 1251 vm_page_t bm, mpred, msucc, p; 1252 vm_pindex_t pindex; 1253 daddr_t blk; 1254 int i, maxahead, maxbehind, reqcount; 1255 1256 VM_OBJECT_ASSERT_WLOCKED(object); 1257 reqcount = count; 1258 1259 KASSERT((object->flags & OBJ_SWAP) != 0, 1260 ("%s: object not swappable", __func__)); 1261 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1262 VM_OBJECT_WUNLOCK(object); 1263 return (VM_PAGER_FAIL); 1264 } 1265 1266 KASSERT(reqcount - 1 <= maxahead, 1267 ("page count %d extends beyond swap block", reqcount)); 1268 1269 /* 1270 * Do not transfer any pages other than those that are xbusied 1271 * when running during a split or collapse operation. This 1272 * prevents clustering from re-creating pages which are being 1273 * moved into another object. 1274 */ 1275 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1276 maxahead = reqcount - 1; 1277 maxbehind = 0; 1278 } 1279 1280 /* 1281 * Clip the readahead and readbehind ranges to exclude resident pages. 1282 */ 1283 if (rahead != NULL) { 1284 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1285 pindex = ma[reqcount - 1]->pindex; 1286 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1287 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1288 *rahead = msucc->pindex - pindex - 1; 1289 } 1290 if (rbehind != NULL) { 1291 *rbehind = imin(*rbehind, maxbehind); 1292 pindex = ma[0]->pindex; 1293 mpred = TAILQ_PREV(ma[0], pglist, listq); 1294 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1295 *rbehind = pindex - mpred->pindex - 1; 1296 } 1297 1298 bm = ma[0]; 1299 for (i = 0; i < count; i++) 1300 ma[i]->oflags |= VPO_SWAPINPROG; 1301 1302 /* 1303 * Allocate readahead and readbehind pages. 1304 */ 1305 if (rbehind != NULL) { 1306 for (i = 1; i <= *rbehind; i++) { 1307 p = vm_page_alloc(object, ma[0]->pindex - i, 1308 VM_ALLOC_NORMAL); 1309 if (p == NULL) 1310 break; 1311 p->oflags |= VPO_SWAPINPROG; 1312 bm = p; 1313 } 1314 *rbehind = i - 1; 1315 } 1316 if (rahead != NULL) { 1317 for (i = 0; i < *rahead; i++) { 1318 p = vm_page_alloc(object, 1319 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1320 if (p == NULL) 1321 break; 1322 p->oflags |= VPO_SWAPINPROG; 1323 } 1324 *rahead = i; 1325 } 1326 if (rbehind != NULL) 1327 count += *rbehind; 1328 if (rahead != NULL) 1329 count += *rahead; 1330 1331 vm_object_pip_add(object, count); 1332 1333 pindex = bm->pindex; 1334 blk = swp_pager_meta_lookup(object, pindex); 1335 KASSERT(blk != SWAPBLK_NONE, 1336 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1337 1338 VM_OBJECT_WUNLOCK(object); 1339 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1340 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1341 /* Pages cannot leave the object while busy. */ 1342 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1343 MPASS(p->pindex == bm->pindex + i); 1344 bp->b_pages[i] = p; 1345 } 1346 1347 bp->b_flags |= B_PAGING; 1348 bp->b_iocmd = BIO_READ; 1349 bp->b_iodone = swp_pager_async_iodone; 1350 bp->b_rcred = crhold(thread0.td_ucred); 1351 bp->b_wcred = crhold(thread0.td_ucred); 1352 bp->b_blkno = blk; 1353 bp->b_bcount = PAGE_SIZE * count; 1354 bp->b_bufsize = PAGE_SIZE * count; 1355 bp->b_npages = count; 1356 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1357 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1358 1359 VM_CNT_INC(v_swapin); 1360 VM_CNT_ADD(v_swappgsin, count); 1361 1362 /* 1363 * perform the I/O. NOTE!!! bp cannot be considered valid after 1364 * this point because we automatically release it on completion. 1365 * Instead, we look at the one page we are interested in which we 1366 * still hold a lock on even through the I/O completion. 1367 * 1368 * The other pages in our ma[] array are also released on completion, 1369 * so we cannot assume they are valid anymore either. 1370 * 1371 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1372 */ 1373 BUF_KERNPROC(bp); 1374 swp_pager_strategy(bp); 1375 1376 /* 1377 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1378 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1379 * is set in the metadata for each page in the request. 1380 */ 1381 VM_OBJECT_WLOCK(object); 1382 /* This could be implemented more efficiently with aflags */ 1383 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1384 ma[0]->oflags |= VPO_SWAPSLEEP; 1385 VM_CNT_INC(v_intrans); 1386 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1387 "swread", hz * 20)) { 1388 printf( 1389 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1390 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1391 } 1392 } 1393 VM_OBJECT_WUNLOCK(object); 1394 1395 /* 1396 * If we had an unrecoverable read error pages will not be valid. 1397 */ 1398 for (i = 0; i < reqcount; i++) 1399 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1400 return (VM_PAGER_ERROR); 1401 1402 return (VM_PAGER_OK); 1403 1404 /* 1405 * A final note: in a low swap situation, we cannot deallocate swap 1406 * and mark a page dirty here because the caller is likely to mark 1407 * the page clean when we return, causing the page to possibly revert 1408 * to all-zero's later. 1409 */ 1410 } 1411 1412 static int 1413 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1414 int *rbehind, int *rahead) 1415 { 1416 1417 VM_OBJECT_WLOCK(object); 1418 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1419 } 1420 1421 /* 1422 * swap_pager_getpages_async(): 1423 * 1424 * Right now this is emulation of asynchronous operation on top of 1425 * swap_pager_getpages(). 1426 */ 1427 static int 1428 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1429 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1430 { 1431 int r, error; 1432 1433 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1434 switch (r) { 1435 case VM_PAGER_OK: 1436 error = 0; 1437 break; 1438 case VM_PAGER_ERROR: 1439 error = EIO; 1440 break; 1441 case VM_PAGER_FAIL: 1442 error = EINVAL; 1443 break; 1444 default: 1445 panic("unhandled swap_pager_getpages() error %d", r); 1446 } 1447 (iodone)(arg, ma, count, error); 1448 1449 return (r); 1450 } 1451 1452 /* 1453 * swap_pager_putpages: 1454 * 1455 * Assign swap (if necessary) and initiate I/O on the specified pages. 1456 * 1457 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1458 * are automatically converted to SWAP objects. 1459 * 1460 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1461 * vm_page reservation system coupled with properly written VFS devices 1462 * should ensure that no low-memory deadlock occurs. This is an area 1463 * which needs work. 1464 * 1465 * The parent has N vm_object_pip_add() references prior to 1466 * calling us and will remove references for rtvals[] that are 1467 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1468 * completion. 1469 * 1470 * The parent has soft-busy'd the pages it passes us and will unbusy 1471 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1472 * We need to unbusy the rest on I/O completion. 1473 */ 1474 static void 1475 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1476 int flags, int *rtvals) 1477 { 1478 struct buf *bp; 1479 daddr_t addr, blk, n_free, s_free; 1480 vm_page_t mreq; 1481 int i, j, n; 1482 bool async; 1483 1484 KASSERT(count == 0 || ma[0]->object == object, 1485 ("%s: object mismatch %p/%p", 1486 __func__, object, ma[0]->object)); 1487 1488 /* 1489 * Step 1 1490 * 1491 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1492 */ 1493 if ((object->flags & OBJ_SWAP) == 0) { 1494 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1495 KASSERT(addr == SWAPBLK_NONE, 1496 ("unexpected object swap block")); 1497 } 1498 VM_OBJECT_WUNLOCK(object); 1499 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1500 swp_pager_init_freerange(&s_free, &n_free); 1501 1502 /* 1503 * Step 2 1504 * 1505 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1506 * The page is left dirty until the pageout operation completes 1507 * successfully. 1508 */ 1509 for (i = 0; i < count; i += n) { 1510 /* Maximum I/O size is limited by maximum swap block size. */ 1511 n = min(count - i, nsw_cluster_max); 1512 1513 if (async) { 1514 mtx_lock(&swbuf_mtx); 1515 while (nsw_wcount_async == 0) 1516 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1517 "swbufa", 0); 1518 nsw_wcount_async--; 1519 mtx_unlock(&swbuf_mtx); 1520 } 1521 1522 /* Get a block of swap of size up to size n. */ 1523 VM_OBJECT_WLOCK(object); 1524 blk = swp_pager_getswapspace(&n); 1525 if (blk == SWAPBLK_NONE) { 1526 VM_OBJECT_WUNLOCK(object); 1527 mtx_lock(&swbuf_mtx); 1528 if (++nsw_wcount_async == 1) 1529 wakeup(&nsw_wcount_async); 1530 mtx_unlock(&swbuf_mtx); 1531 for (j = 0; j < n; ++j) 1532 rtvals[i + j] = VM_PAGER_FAIL; 1533 continue; 1534 } 1535 for (j = 0; j < n; ++j) { 1536 mreq = ma[i + j]; 1537 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1538 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1539 blk + j); 1540 if (addr != SWAPBLK_NONE) 1541 swp_pager_update_freerange(&s_free, &n_free, 1542 addr); 1543 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1544 mreq->oflags |= VPO_SWAPINPROG; 1545 } 1546 VM_OBJECT_WUNLOCK(object); 1547 1548 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1549 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1550 if (async) 1551 bp->b_flags |= B_ASYNC; 1552 bp->b_flags |= B_PAGING; 1553 bp->b_iocmd = BIO_WRITE; 1554 1555 bp->b_rcred = crhold(thread0.td_ucred); 1556 bp->b_wcred = crhold(thread0.td_ucred); 1557 bp->b_bcount = PAGE_SIZE * n; 1558 bp->b_bufsize = PAGE_SIZE * n; 1559 bp->b_blkno = blk; 1560 for (j = 0; j < n; j++) 1561 bp->b_pages[j] = ma[i + j]; 1562 bp->b_npages = n; 1563 1564 /* 1565 * Must set dirty range for NFS to work. 1566 */ 1567 bp->b_dirtyoff = 0; 1568 bp->b_dirtyend = bp->b_bcount; 1569 1570 VM_CNT_INC(v_swapout); 1571 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1572 1573 /* 1574 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1575 * can call the async completion routine at the end of a 1576 * synchronous I/O operation. Otherwise, our caller would 1577 * perform duplicate unbusy and wakeup operations on the page 1578 * and object, respectively. 1579 */ 1580 for (j = 0; j < n; j++) 1581 rtvals[i + j] = VM_PAGER_PEND; 1582 1583 /* 1584 * asynchronous 1585 * 1586 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1587 */ 1588 if (async) { 1589 bp->b_iodone = swp_pager_async_iodone; 1590 BUF_KERNPROC(bp); 1591 swp_pager_strategy(bp); 1592 continue; 1593 } 1594 1595 /* 1596 * synchronous 1597 * 1598 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1599 */ 1600 bp->b_iodone = bdone; 1601 swp_pager_strategy(bp); 1602 1603 /* 1604 * Wait for the sync I/O to complete. 1605 */ 1606 bwait(bp, PVM, "swwrt"); 1607 1608 /* 1609 * Now that we are through with the bp, we can call the 1610 * normal async completion, which frees everything up. 1611 */ 1612 swp_pager_async_iodone(bp); 1613 } 1614 swp_pager_freeswapspace(s_free, n_free); 1615 VM_OBJECT_WLOCK(object); 1616 } 1617 1618 /* 1619 * swp_pager_async_iodone: 1620 * 1621 * Completion routine for asynchronous reads and writes from/to swap. 1622 * Also called manually by synchronous code to finish up a bp. 1623 * 1624 * This routine may not sleep. 1625 */ 1626 static void 1627 swp_pager_async_iodone(struct buf *bp) 1628 { 1629 int i; 1630 vm_object_t object = NULL; 1631 1632 /* 1633 * Report error - unless we ran out of memory, in which case 1634 * we've already logged it in swapgeom_strategy(). 1635 */ 1636 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1637 printf( 1638 "swap_pager: I/O error - %s failed; blkno %ld," 1639 "size %ld, error %d\n", 1640 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1641 (long)bp->b_blkno, 1642 (long)bp->b_bcount, 1643 bp->b_error 1644 ); 1645 } 1646 1647 /* 1648 * remove the mapping for kernel virtual 1649 */ 1650 if (buf_mapped(bp)) 1651 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1652 else 1653 bp->b_data = bp->b_kvabase; 1654 1655 if (bp->b_npages) { 1656 object = bp->b_pages[0]->object; 1657 VM_OBJECT_WLOCK(object); 1658 } 1659 1660 /* 1661 * cleanup pages. If an error occurs writing to swap, we are in 1662 * very serious trouble. If it happens to be a disk error, though, 1663 * we may be able to recover by reassigning the swap later on. So 1664 * in this case we remove the m->swapblk assignment for the page 1665 * but do not free it in the rlist. The errornous block(s) are thus 1666 * never reallocated as swap. Redirty the page and continue. 1667 */ 1668 for (i = 0; i < bp->b_npages; ++i) { 1669 vm_page_t m = bp->b_pages[i]; 1670 1671 m->oflags &= ~VPO_SWAPINPROG; 1672 if (m->oflags & VPO_SWAPSLEEP) { 1673 m->oflags &= ~VPO_SWAPSLEEP; 1674 wakeup(&object->handle); 1675 } 1676 1677 /* We always have space after I/O, successful or not. */ 1678 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1679 1680 if (bp->b_ioflags & BIO_ERROR) { 1681 /* 1682 * If an error occurs I'd love to throw the swapblk 1683 * away without freeing it back to swapspace, so it 1684 * can never be used again. But I can't from an 1685 * interrupt. 1686 */ 1687 if (bp->b_iocmd == BIO_READ) { 1688 /* 1689 * NOTE: for reads, m->dirty will probably 1690 * be overridden by the original caller of 1691 * getpages so don't play cute tricks here. 1692 */ 1693 vm_page_invalid(m); 1694 } else { 1695 /* 1696 * If a write error occurs, reactivate page 1697 * so it doesn't clog the inactive list, 1698 * then finish the I/O. 1699 */ 1700 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1701 1702 /* PQ_UNSWAPPABLE? */ 1703 vm_page_activate(m); 1704 vm_page_sunbusy(m); 1705 } 1706 } else if (bp->b_iocmd == BIO_READ) { 1707 /* 1708 * NOTE: for reads, m->dirty will probably be 1709 * overridden by the original caller of getpages so 1710 * we cannot set them in order to free the underlying 1711 * swap in a low-swap situation. I don't think we'd 1712 * want to do that anyway, but it was an optimization 1713 * that existed in the old swapper for a time before 1714 * it got ripped out due to precisely this problem. 1715 */ 1716 KASSERT(!pmap_page_is_mapped(m), 1717 ("swp_pager_async_iodone: page %p is mapped", m)); 1718 KASSERT(m->dirty == 0, 1719 ("swp_pager_async_iodone: page %p is dirty", m)); 1720 1721 vm_page_valid(m); 1722 if (i < bp->b_pgbefore || 1723 i >= bp->b_npages - bp->b_pgafter) 1724 vm_page_readahead_finish(m); 1725 } else { 1726 /* 1727 * For write success, clear the dirty 1728 * status, then finish the I/O ( which decrements the 1729 * busy count and possibly wakes waiter's up ). 1730 * A page is only written to swap after a period of 1731 * inactivity. Therefore, we do not expect it to be 1732 * reused. 1733 */ 1734 KASSERT(!pmap_page_is_write_mapped(m), 1735 ("swp_pager_async_iodone: page %p is not write" 1736 " protected", m)); 1737 vm_page_undirty(m); 1738 vm_page_deactivate_noreuse(m); 1739 vm_page_sunbusy(m); 1740 } 1741 } 1742 1743 /* 1744 * adjust pip. NOTE: the original parent may still have its own 1745 * pip refs on the object. 1746 */ 1747 if (object != NULL) { 1748 vm_object_pip_wakeupn(object, bp->b_npages); 1749 VM_OBJECT_WUNLOCK(object); 1750 } 1751 1752 /* 1753 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1754 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1755 * trigger a KASSERT in relpbuf(). 1756 */ 1757 if (bp->b_vp) { 1758 bp->b_vp = NULL; 1759 bp->b_bufobj = NULL; 1760 } 1761 /* 1762 * release the physical I/O buffer 1763 */ 1764 if (bp->b_flags & B_ASYNC) { 1765 mtx_lock(&swbuf_mtx); 1766 if (++nsw_wcount_async == 1) 1767 wakeup(&nsw_wcount_async); 1768 mtx_unlock(&swbuf_mtx); 1769 } 1770 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1771 } 1772 1773 int 1774 swap_pager_nswapdev(void) 1775 { 1776 1777 return (nswapdev); 1778 } 1779 1780 static void 1781 swp_pager_force_dirty(vm_page_t m) 1782 { 1783 1784 vm_page_dirty(m); 1785 swap_pager_unswapped(m); 1786 vm_page_launder(m); 1787 } 1788 1789 u_long 1790 swap_pager_swapped_pages(vm_object_t object) 1791 { 1792 struct swblk *sb; 1793 vm_pindex_t pi; 1794 u_long res; 1795 int i; 1796 1797 VM_OBJECT_ASSERT_LOCKED(object); 1798 if ((object->flags & OBJ_SWAP) == 0) 1799 return (0); 1800 1801 for (res = 0, pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1802 &object->un_pager.swp.swp_blks, pi)) != NULL; 1803 pi = sb->p + SWAP_META_PAGES) { 1804 for (i = 0; i < SWAP_META_PAGES; i++) { 1805 if (sb->d[i] != SWAPBLK_NONE) 1806 res++; 1807 } 1808 } 1809 return (res); 1810 } 1811 1812 /* 1813 * swap_pager_swapoff_object: 1814 * 1815 * Page in all of the pages that have been paged out for an object 1816 * to a swap device. 1817 */ 1818 static void 1819 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1820 { 1821 struct swblk *sb; 1822 vm_page_t m; 1823 vm_pindex_t pi; 1824 daddr_t blk; 1825 int i, nv, rahead, rv; 1826 1827 KASSERT((object->flags & OBJ_SWAP) != 0, 1828 ("%s: Object not swappable", __func__)); 1829 1830 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1831 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1832 if ((object->flags & OBJ_DEAD) != 0) { 1833 /* 1834 * Make sure that pending writes finish before 1835 * returning. 1836 */ 1837 vm_object_pip_wait(object, "swpoff"); 1838 swp_pager_meta_free_all(object); 1839 break; 1840 } 1841 for (i = 0; i < SWAP_META_PAGES; i++) { 1842 /* 1843 * Count the number of contiguous valid blocks. 1844 */ 1845 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1846 blk = sb->d[i + nv]; 1847 if (!swp_pager_isondev(blk, sp) || 1848 blk == SWAPBLK_NONE) 1849 break; 1850 } 1851 if (nv == 0) 1852 continue; 1853 1854 /* 1855 * Look for a page corresponding to the first 1856 * valid block and ensure that any pending paging 1857 * operations on it are complete. If the page is valid, 1858 * mark it dirty and free the swap block. Try to batch 1859 * this operation since it may cause sp to be freed, 1860 * meaning that we must restart the scan. Avoid busying 1861 * valid pages since we may block forever on kernel 1862 * stack pages. 1863 */ 1864 m = vm_page_lookup(object, sb->p + i); 1865 if (m == NULL) { 1866 m = vm_page_alloc(object, sb->p + i, 1867 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1868 if (m == NULL) 1869 break; 1870 } else { 1871 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1872 m->oflags |= VPO_SWAPSLEEP; 1873 VM_OBJECT_SLEEP(object, &object->handle, 1874 PSWP, "swpoff", 0); 1875 break; 1876 } 1877 if (vm_page_all_valid(m)) { 1878 do { 1879 swp_pager_force_dirty(m); 1880 } while (--nv > 0 && 1881 (m = vm_page_next(m)) != NULL && 1882 vm_page_all_valid(m) && 1883 (m->oflags & VPO_SWAPINPROG) == 0); 1884 break; 1885 } 1886 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1887 break; 1888 } 1889 1890 vm_object_pip_add(object, 1); 1891 rahead = SWAP_META_PAGES; 1892 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1893 &rahead); 1894 if (rv != VM_PAGER_OK) 1895 panic("%s: read from swap failed: %d", 1896 __func__, rv); 1897 vm_object_pip_wakeupn(object, 1); 1898 VM_OBJECT_WLOCK(object); 1899 vm_page_xunbusy(m); 1900 1901 /* 1902 * The object lock was dropped so we must restart the 1903 * scan of this swap block. Pages paged in during this 1904 * iteration will be marked dirty in a future iteration. 1905 */ 1906 break; 1907 } 1908 if (i == SWAP_META_PAGES) 1909 pi = sb->p + SWAP_META_PAGES; 1910 } 1911 } 1912 1913 /* 1914 * swap_pager_swapoff: 1915 * 1916 * Page in all of the pages that have been paged out to the 1917 * given device. The corresponding blocks in the bitmap must be 1918 * marked as allocated and the device must be flagged SW_CLOSING. 1919 * There may be no processes swapped out to the device. 1920 * 1921 * This routine may block. 1922 */ 1923 static void 1924 swap_pager_swapoff(struct swdevt *sp) 1925 { 1926 vm_object_t object; 1927 int retries; 1928 1929 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1930 1931 retries = 0; 1932 full_rescan: 1933 mtx_lock(&vm_object_list_mtx); 1934 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1935 if ((object->flags & OBJ_SWAP) == 0) 1936 continue; 1937 mtx_unlock(&vm_object_list_mtx); 1938 /* Depends on type-stability. */ 1939 VM_OBJECT_WLOCK(object); 1940 1941 /* 1942 * Dead objects are eventually terminated on their own. 1943 */ 1944 if ((object->flags & OBJ_DEAD) != 0) 1945 goto next_obj; 1946 1947 /* 1948 * Sync with fences placed after pctrie 1949 * initialization. We must not access pctrie below 1950 * unless we checked that our object is swap and not 1951 * dead. 1952 */ 1953 atomic_thread_fence_acq(); 1954 if ((object->flags & OBJ_SWAP) == 0) 1955 goto next_obj; 1956 1957 swap_pager_swapoff_object(sp, object); 1958 next_obj: 1959 VM_OBJECT_WUNLOCK(object); 1960 mtx_lock(&vm_object_list_mtx); 1961 } 1962 mtx_unlock(&vm_object_list_mtx); 1963 1964 if (sp->sw_used) { 1965 /* 1966 * Objects may be locked or paging to the device being 1967 * removed, so we will miss their pages and need to 1968 * make another pass. We have marked this device as 1969 * SW_CLOSING, so the activity should finish soon. 1970 */ 1971 retries++; 1972 if (retries > 100) { 1973 panic("swapoff: failed to locate %d swap blocks", 1974 sp->sw_used); 1975 } 1976 pause("swpoff", hz / 20); 1977 goto full_rescan; 1978 } 1979 EVENTHANDLER_INVOKE(swapoff, sp); 1980 } 1981 1982 /************************************************************************ 1983 * SWAP META DATA * 1984 ************************************************************************ 1985 * 1986 * These routines manipulate the swap metadata stored in the 1987 * OBJT_SWAP object. 1988 * 1989 * Swap metadata is implemented with a global hash and not directly 1990 * linked into the object. Instead the object simply contains 1991 * appropriate tracking counters. 1992 */ 1993 1994 /* 1995 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1996 */ 1997 static bool 1998 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1999 { 2000 int i; 2001 2002 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 2003 for (i = start; i < limit; i++) { 2004 if (sb->d[i] != SWAPBLK_NONE) 2005 return (false); 2006 } 2007 return (true); 2008 } 2009 2010 /* 2011 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 2012 * 2013 * Nothing is done if the block is still in use. 2014 */ 2015 static void 2016 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 2017 { 2018 2019 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2020 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2021 uma_zfree(swblk_zone, sb); 2022 } 2023 } 2024 2025 /* 2026 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2027 * 2028 * We first convert the object to a swap object if it is a default 2029 * object. 2030 * 2031 * The specified swapblk is added to the object's swap metadata. If 2032 * the swapblk is not valid, it is freed instead. Any previously 2033 * assigned swapblk is returned. 2034 */ 2035 static daddr_t 2036 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 2037 { 2038 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 2039 struct swblk *sb, *sb1; 2040 vm_pindex_t modpi, rdpi; 2041 daddr_t prev_swapblk; 2042 int error, i; 2043 2044 VM_OBJECT_ASSERT_WLOCKED(object); 2045 2046 /* 2047 * Convert default object to swap object if necessary 2048 */ 2049 if ((object->flags & OBJ_SWAP) == 0) { 2050 pctrie_init(&object->un_pager.swp.swp_blks); 2051 2052 /* 2053 * Ensure that swap_pager_swapoff()'s iteration over 2054 * object_list does not see a garbage pctrie. 2055 */ 2056 atomic_thread_fence_rel(); 2057 2058 object->type = OBJT_SWAP; 2059 vm_object_set_flag(object, OBJ_SWAP); 2060 object->un_pager.swp.writemappings = 0; 2061 KASSERT((object->flags & OBJ_ANON) != 0 || 2062 object->handle == NULL, 2063 ("default pager %p with handle %p", 2064 object, object->handle)); 2065 } 2066 2067 rdpi = rounddown(pindex, SWAP_META_PAGES); 2068 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 2069 if (sb == NULL) { 2070 if (swapblk == SWAPBLK_NONE) 2071 return (SWAPBLK_NONE); 2072 for (;;) { 2073 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 2074 pageproc ? M_USE_RESERVE : 0)); 2075 if (sb != NULL) { 2076 sb->p = rdpi; 2077 for (i = 0; i < SWAP_META_PAGES; i++) 2078 sb->d[i] = SWAPBLK_NONE; 2079 if (atomic_cmpset_int(&swblk_zone_exhausted, 2080 1, 0)) 2081 printf("swblk zone ok\n"); 2082 break; 2083 } 2084 VM_OBJECT_WUNLOCK(object); 2085 if (uma_zone_exhausted(swblk_zone)) { 2086 if (atomic_cmpset_int(&swblk_zone_exhausted, 2087 0, 1)) 2088 printf("swap blk zone exhausted, " 2089 "increase kern.maxswzone\n"); 2090 vm_pageout_oom(VM_OOM_SWAPZ); 2091 pause("swzonxb", 10); 2092 } else 2093 uma_zwait(swblk_zone); 2094 VM_OBJECT_WLOCK(object); 2095 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2096 rdpi); 2097 if (sb != NULL) 2098 /* 2099 * Somebody swapped out a nearby page, 2100 * allocating swblk at the rdpi index, 2101 * while we dropped the object lock. 2102 */ 2103 goto allocated; 2104 } 2105 for (;;) { 2106 error = SWAP_PCTRIE_INSERT( 2107 &object->un_pager.swp.swp_blks, sb); 2108 if (error == 0) { 2109 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2110 1, 0)) 2111 printf("swpctrie zone ok\n"); 2112 break; 2113 } 2114 VM_OBJECT_WUNLOCK(object); 2115 if (uma_zone_exhausted(swpctrie_zone)) { 2116 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2117 0, 1)) 2118 printf("swap pctrie zone exhausted, " 2119 "increase kern.maxswzone\n"); 2120 vm_pageout_oom(VM_OOM_SWAPZ); 2121 pause("swzonxp", 10); 2122 } else 2123 uma_zwait(swpctrie_zone); 2124 VM_OBJECT_WLOCK(object); 2125 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2126 rdpi); 2127 if (sb1 != NULL) { 2128 uma_zfree(swblk_zone, sb); 2129 sb = sb1; 2130 goto allocated; 2131 } 2132 } 2133 } 2134 allocated: 2135 MPASS(sb->p == rdpi); 2136 2137 modpi = pindex % SWAP_META_PAGES; 2138 /* Return prior contents of metadata. */ 2139 prev_swapblk = sb->d[modpi]; 2140 /* Enter block into metadata. */ 2141 sb->d[modpi] = swapblk; 2142 2143 /* 2144 * Free the swblk if we end up with the empty page run. 2145 */ 2146 if (swapblk == SWAPBLK_NONE) 2147 swp_pager_free_empty_swblk(object, sb); 2148 return (prev_swapblk); 2149 } 2150 2151 /* 2152 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2153 * metadata, or transfer it into dstobject. 2154 * 2155 * This routine will free swap metadata structures as they are cleaned 2156 * out. 2157 */ 2158 static void 2159 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2160 vm_pindex_t pindex, vm_pindex_t count) 2161 { 2162 struct swblk *sb; 2163 daddr_t n_free, s_free; 2164 vm_pindex_t offset, last; 2165 int i, limit, start; 2166 2167 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2168 if ((srcobject->flags & OBJ_SWAP) == 0 || count == 0) 2169 return; 2170 2171 swp_pager_init_freerange(&s_free, &n_free); 2172 offset = pindex; 2173 last = pindex + count; 2174 for (;;) { 2175 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2176 rounddown(pindex, SWAP_META_PAGES)); 2177 if (sb == NULL || sb->p >= last) 2178 break; 2179 start = pindex > sb->p ? pindex - sb->p : 0; 2180 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2181 SWAP_META_PAGES; 2182 for (i = start; i < limit; i++) { 2183 if (sb->d[i] == SWAPBLK_NONE) 2184 continue; 2185 if (dstobject == NULL || 2186 !swp_pager_xfer_source(srcobject, dstobject, 2187 sb->p + i - offset, sb->d[i])) { 2188 swp_pager_update_freerange(&s_free, &n_free, 2189 sb->d[i]); 2190 } 2191 sb->d[i] = SWAPBLK_NONE; 2192 } 2193 pindex = sb->p + SWAP_META_PAGES; 2194 if (swp_pager_swblk_empty(sb, 0, start) && 2195 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2196 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2197 sb->p); 2198 uma_zfree(swblk_zone, sb); 2199 } 2200 } 2201 swp_pager_freeswapspace(s_free, n_free); 2202 } 2203 2204 /* 2205 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2206 * 2207 * The requested range of blocks is freed, with any associated swap 2208 * returned to the swap bitmap. 2209 * 2210 * This routine will free swap metadata structures as they are cleaned 2211 * out. This routine does *NOT* operate on swap metadata associated 2212 * with resident pages. 2213 */ 2214 static void 2215 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2216 { 2217 swp_pager_meta_transfer(object, NULL, pindex, count); 2218 } 2219 2220 /* 2221 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2222 * 2223 * This routine locates and destroys all swap metadata associated with 2224 * an object. 2225 */ 2226 static void 2227 swp_pager_meta_free_all(vm_object_t object) 2228 { 2229 struct swblk *sb; 2230 daddr_t n_free, s_free; 2231 vm_pindex_t pindex; 2232 int i; 2233 2234 VM_OBJECT_ASSERT_WLOCKED(object); 2235 if ((object->flags & OBJ_SWAP) == 0) 2236 return; 2237 2238 swp_pager_init_freerange(&s_free, &n_free); 2239 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2240 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2241 pindex = sb->p + SWAP_META_PAGES; 2242 for (i = 0; i < SWAP_META_PAGES; i++) { 2243 if (sb->d[i] == SWAPBLK_NONE) 2244 continue; 2245 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2246 } 2247 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2248 uma_zfree(swblk_zone, sb); 2249 } 2250 swp_pager_freeswapspace(s_free, n_free); 2251 } 2252 2253 /* 2254 * SWP_PAGER_METACTL() - misc control of swap meta data. 2255 * 2256 * This routine is capable of looking up, or removing swapblk 2257 * assignments in the swap meta data. It returns the swapblk being 2258 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2259 * 2260 * When acting on a busy resident page and paging is in progress, we 2261 * have to wait until paging is complete but otherwise can act on the 2262 * busy page. 2263 */ 2264 static daddr_t 2265 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2266 { 2267 struct swblk *sb; 2268 2269 VM_OBJECT_ASSERT_LOCKED(object); 2270 2271 /* 2272 * The meta data only exists if the object is OBJT_SWAP 2273 * and even then might not be allocated yet. 2274 */ 2275 KASSERT((object->flags & OBJ_SWAP) != 0, 2276 ("Lookup object not swappable")); 2277 2278 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2279 rounddown(pindex, SWAP_META_PAGES)); 2280 if (sb == NULL) 2281 return (SWAPBLK_NONE); 2282 return (sb->d[pindex % SWAP_META_PAGES]); 2283 } 2284 2285 /* 2286 * Returns the least page index which is greater than or equal to the 2287 * parameter pindex and for which there is a swap block allocated. 2288 * Returns object's size if the object's type is not swap or if there 2289 * are no allocated swap blocks for the object after the requested 2290 * pindex. 2291 */ 2292 vm_pindex_t 2293 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2294 { 2295 struct swblk *sb; 2296 int i; 2297 2298 VM_OBJECT_ASSERT_LOCKED(object); 2299 if ((object->flags & OBJ_SWAP) == 0) 2300 return (object->size); 2301 2302 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2303 rounddown(pindex, SWAP_META_PAGES)); 2304 if (sb == NULL) 2305 return (object->size); 2306 if (sb->p < pindex) { 2307 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2308 if (sb->d[i] != SWAPBLK_NONE) 2309 return (sb->p + i); 2310 } 2311 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2312 roundup(pindex, SWAP_META_PAGES)); 2313 if (sb == NULL) 2314 return (object->size); 2315 } 2316 for (i = 0; i < SWAP_META_PAGES; i++) { 2317 if (sb->d[i] != SWAPBLK_NONE) 2318 return (sb->p + i); 2319 } 2320 2321 /* 2322 * We get here if a swblk is present in the trie but it 2323 * doesn't map any blocks. 2324 */ 2325 MPASS(0); 2326 return (object->size); 2327 } 2328 2329 /* 2330 * System call swapon(name) enables swapping on device name, 2331 * which must be in the swdevsw. Return EBUSY 2332 * if already swapping on this device. 2333 */ 2334 #ifndef _SYS_SYSPROTO_H_ 2335 struct swapon_args { 2336 char *name; 2337 }; 2338 #endif 2339 2340 int 2341 sys_swapon(struct thread *td, struct swapon_args *uap) 2342 { 2343 struct vattr attr; 2344 struct vnode *vp; 2345 struct nameidata nd; 2346 int error; 2347 2348 error = priv_check(td, PRIV_SWAPON); 2349 if (error) 2350 return (error); 2351 2352 sx_xlock(&swdev_syscall_lock); 2353 2354 /* 2355 * Swap metadata may not fit in the KVM if we have physical 2356 * memory of >1GB. 2357 */ 2358 if (swblk_zone == NULL) { 2359 error = ENOMEM; 2360 goto done; 2361 } 2362 2363 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1, 2364 UIO_USERSPACE, uap->name); 2365 error = namei(&nd); 2366 if (error) 2367 goto done; 2368 2369 NDFREE(&nd, NDF_ONLY_PNBUF); 2370 vp = nd.ni_vp; 2371 2372 if (vn_isdisk_error(vp, &error)) { 2373 error = swapongeom(vp); 2374 } else if (vp->v_type == VREG && 2375 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2376 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2377 /* 2378 * Allow direct swapping to NFS regular files in the same 2379 * way that nfs_mountroot() sets up diskless swapping. 2380 */ 2381 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2382 } 2383 2384 if (error != 0) 2385 vput(vp); 2386 else 2387 VOP_UNLOCK(vp); 2388 done: 2389 sx_xunlock(&swdev_syscall_lock); 2390 return (error); 2391 } 2392 2393 /* 2394 * Check that the total amount of swap currently configured does not 2395 * exceed half the theoretical maximum. If it does, print a warning 2396 * message. 2397 */ 2398 static void 2399 swapon_check_swzone(void) 2400 { 2401 2402 /* recommend using no more than half that amount */ 2403 if (swap_total > swap_maxpages / 2) { 2404 printf("warning: total configured swap (%lu pages) " 2405 "exceeds maximum recommended amount (%lu pages).\n", 2406 swap_total, swap_maxpages / 2); 2407 printf("warning: increase kern.maxswzone " 2408 "or reduce amount of swap.\n"); 2409 } 2410 } 2411 2412 static void 2413 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2414 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2415 { 2416 struct swdevt *sp, *tsp; 2417 daddr_t dvbase; 2418 2419 /* 2420 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2421 * First chop nblks off to page-align it, then convert. 2422 * 2423 * sw->sw_nblks is in page-sized chunks now too. 2424 */ 2425 nblks &= ~(ctodb(1) - 1); 2426 nblks = dbtoc(nblks); 2427 2428 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2429 sp->sw_blist = blist_create(nblks, M_WAITOK); 2430 sp->sw_vp = vp; 2431 sp->sw_id = id; 2432 sp->sw_dev = dev; 2433 sp->sw_nblks = nblks; 2434 sp->sw_used = 0; 2435 sp->sw_strategy = strategy; 2436 sp->sw_close = close; 2437 sp->sw_flags = flags; 2438 2439 /* 2440 * Do not free the first blocks in order to avoid overwriting 2441 * any bsd label at the front of the partition 2442 */ 2443 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2444 nblks - howmany(BBSIZE, PAGE_SIZE)); 2445 2446 dvbase = 0; 2447 mtx_lock(&sw_dev_mtx); 2448 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2449 if (tsp->sw_end >= dvbase) { 2450 /* 2451 * We put one uncovered page between the devices 2452 * in order to definitively prevent any cross-device 2453 * I/O requests 2454 */ 2455 dvbase = tsp->sw_end + 1; 2456 } 2457 } 2458 sp->sw_first = dvbase; 2459 sp->sw_end = dvbase + nblks; 2460 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2461 nswapdev++; 2462 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2463 swap_total += nblks; 2464 swapon_check_swzone(); 2465 swp_sizecheck(); 2466 mtx_unlock(&sw_dev_mtx); 2467 EVENTHANDLER_INVOKE(swapon, sp); 2468 } 2469 2470 /* 2471 * SYSCALL: swapoff(devname) 2472 * 2473 * Disable swapping on the given device. 2474 * 2475 * XXX: Badly designed system call: it should use a device index 2476 * rather than filename as specification. We keep sw_vp around 2477 * only to make this work. 2478 */ 2479 static int 2480 kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg, 2481 u_int flags) 2482 { 2483 struct vnode *vp; 2484 struct nameidata nd; 2485 struct swdevt *sp; 2486 int error; 2487 2488 error = priv_check(td, PRIV_SWAPOFF); 2489 if (error != 0) 2490 return (error); 2491 if ((flags & ~(SWAPOFF_FORCE)) != 0) 2492 return (EINVAL); 2493 2494 sx_xlock(&swdev_syscall_lock); 2495 2496 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name); 2497 error = namei(&nd); 2498 if (error) 2499 goto done; 2500 NDFREE(&nd, NDF_ONLY_PNBUF); 2501 vp = nd.ni_vp; 2502 2503 mtx_lock(&sw_dev_mtx); 2504 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2505 if (sp->sw_vp == vp) 2506 break; 2507 } 2508 mtx_unlock(&sw_dev_mtx); 2509 if (sp == NULL) { 2510 error = EINVAL; 2511 goto done; 2512 } 2513 error = swapoff_one(sp, td->td_ucred, flags); 2514 done: 2515 sx_xunlock(&swdev_syscall_lock); 2516 return (error); 2517 } 2518 2519 2520 #ifdef COMPAT_FREEBSD13 2521 int 2522 freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap) 2523 { 2524 return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0)); 2525 } 2526 #endif 2527 2528 int 2529 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2530 { 2531 return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags)); 2532 } 2533 2534 static int 2535 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags) 2536 { 2537 u_long nblks; 2538 #ifdef MAC 2539 int error; 2540 #endif 2541 2542 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2543 #ifdef MAC 2544 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2545 error = mac_system_check_swapoff(cred, sp->sw_vp); 2546 (void) VOP_UNLOCK(sp->sw_vp); 2547 if (error != 0) 2548 return (error); 2549 #endif 2550 nblks = sp->sw_nblks; 2551 2552 /* 2553 * We can turn off this swap device safely only if the 2554 * available virtual memory in the system will fit the amount 2555 * of data we will have to page back in, plus an epsilon so 2556 * the system doesn't become critically low on swap space. 2557 * The vm_free_count() part does not account e.g. for clean 2558 * pages that can be immediately reclaimed without paging, so 2559 * this is a very rough estimation. 2560 * 2561 * On the other hand, not turning swap off on swapoff_all() 2562 * means that we can lose swap data when filesystems go away, 2563 * which is arguably worse. 2564 */ 2565 if ((flags & SWAPOFF_FORCE) == 0 && 2566 vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2567 return (ENOMEM); 2568 2569 /* 2570 * Prevent further allocations on this device. 2571 */ 2572 mtx_lock(&sw_dev_mtx); 2573 sp->sw_flags |= SW_CLOSING; 2574 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2575 swap_total -= nblks; 2576 mtx_unlock(&sw_dev_mtx); 2577 2578 /* 2579 * Page in the contents of the device and close it. 2580 */ 2581 swap_pager_swapoff(sp); 2582 2583 sp->sw_close(curthread, sp); 2584 mtx_lock(&sw_dev_mtx); 2585 sp->sw_id = NULL; 2586 TAILQ_REMOVE(&swtailq, sp, sw_list); 2587 nswapdev--; 2588 if (nswapdev == 0) { 2589 swap_pager_full = 2; 2590 swap_pager_almost_full = 1; 2591 } 2592 if (swdevhd == sp) 2593 swdevhd = NULL; 2594 mtx_unlock(&sw_dev_mtx); 2595 blist_destroy(sp->sw_blist); 2596 free(sp, M_VMPGDATA); 2597 return (0); 2598 } 2599 2600 void 2601 swapoff_all(void) 2602 { 2603 struct swdevt *sp, *spt; 2604 const char *devname; 2605 int error; 2606 2607 sx_xlock(&swdev_syscall_lock); 2608 2609 mtx_lock(&sw_dev_mtx); 2610 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2611 mtx_unlock(&sw_dev_mtx); 2612 if (vn_isdisk(sp->sw_vp)) 2613 devname = devtoname(sp->sw_vp->v_rdev); 2614 else 2615 devname = "[file]"; 2616 error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE); 2617 if (error != 0) { 2618 printf("Cannot remove swap device %s (error=%d), " 2619 "skipping.\n", devname, error); 2620 } else if (bootverbose) { 2621 printf("Swap device %s removed.\n", devname); 2622 } 2623 mtx_lock(&sw_dev_mtx); 2624 } 2625 mtx_unlock(&sw_dev_mtx); 2626 2627 sx_xunlock(&swdev_syscall_lock); 2628 } 2629 2630 void 2631 swap_pager_status(int *total, int *used) 2632 { 2633 2634 *total = swap_total; 2635 *used = swap_total - swap_pager_avail - 2636 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2637 } 2638 2639 int 2640 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2641 { 2642 struct swdevt *sp; 2643 const char *tmp_devname; 2644 int error, n; 2645 2646 n = 0; 2647 error = ENOENT; 2648 mtx_lock(&sw_dev_mtx); 2649 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2650 if (n != name) { 2651 n++; 2652 continue; 2653 } 2654 xs->xsw_version = XSWDEV_VERSION; 2655 xs->xsw_dev = sp->sw_dev; 2656 xs->xsw_flags = sp->sw_flags; 2657 xs->xsw_nblks = sp->sw_nblks; 2658 xs->xsw_used = sp->sw_used; 2659 if (devname != NULL) { 2660 if (vn_isdisk(sp->sw_vp)) 2661 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2662 else 2663 tmp_devname = "[file]"; 2664 strncpy(devname, tmp_devname, len); 2665 } 2666 error = 0; 2667 break; 2668 } 2669 mtx_unlock(&sw_dev_mtx); 2670 return (error); 2671 } 2672 2673 #if defined(COMPAT_FREEBSD11) 2674 #define XSWDEV_VERSION_11 1 2675 struct xswdev11 { 2676 u_int xsw_version; 2677 uint32_t xsw_dev; 2678 int xsw_flags; 2679 int xsw_nblks; 2680 int xsw_used; 2681 }; 2682 #endif 2683 2684 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2685 struct xswdev32 { 2686 u_int xsw_version; 2687 u_int xsw_dev1, xsw_dev2; 2688 int xsw_flags; 2689 int xsw_nblks; 2690 int xsw_used; 2691 }; 2692 #endif 2693 2694 static int 2695 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2696 { 2697 struct xswdev xs; 2698 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2699 struct xswdev32 xs32; 2700 #endif 2701 #if defined(COMPAT_FREEBSD11) 2702 struct xswdev11 xs11; 2703 #endif 2704 int error; 2705 2706 if (arg2 != 1) /* name length */ 2707 return (EINVAL); 2708 2709 memset(&xs, 0, sizeof(xs)); 2710 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2711 if (error != 0) 2712 return (error); 2713 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2714 if (req->oldlen == sizeof(xs32)) { 2715 memset(&xs32, 0, sizeof(xs32)); 2716 xs32.xsw_version = XSWDEV_VERSION; 2717 xs32.xsw_dev1 = xs.xsw_dev; 2718 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2719 xs32.xsw_flags = xs.xsw_flags; 2720 xs32.xsw_nblks = xs.xsw_nblks; 2721 xs32.xsw_used = xs.xsw_used; 2722 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2723 return (error); 2724 } 2725 #endif 2726 #if defined(COMPAT_FREEBSD11) 2727 if (req->oldlen == sizeof(xs11)) { 2728 memset(&xs11, 0, sizeof(xs11)); 2729 xs11.xsw_version = XSWDEV_VERSION_11; 2730 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2731 xs11.xsw_flags = xs.xsw_flags; 2732 xs11.xsw_nblks = xs.xsw_nblks; 2733 xs11.xsw_used = xs.xsw_used; 2734 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2735 return (error); 2736 } 2737 #endif 2738 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2739 return (error); 2740 } 2741 2742 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2743 "Number of swap devices"); 2744 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2745 sysctl_vm_swap_info, 2746 "Swap statistics by device"); 2747 2748 /* 2749 * Count the approximate swap usage in pages for a vmspace. The 2750 * shadowed or not yet copied on write swap blocks are not accounted. 2751 * The map must be locked. 2752 */ 2753 long 2754 vmspace_swap_count(struct vmspace *vmspace) 2755 { 2756 vm_map_t map; 2757 vm_map_entry_t cur; 2758 vm_object_t object; 2759 struct swblk *sb; 2760 vm_pindex_t e, pi; 2761 long count; 2762 int i; 2763 2764 map = &vmspace->vm_map; 2765 count = 0; 2766 2767 VM_MAP_ENTRY_FOREACH(cur, map) { 2768 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2769 continue; 2770 object = cur->object.vm_object; 2771 if (object == NULL || (object->flags & OBJ_SWAP) == 0) 2772 continue; 2773 VM_OBJECT_RLOCK(object); 2774 if ((object->flags & OBJ_SWAP) == 0) 2775 goto unlock; 2776 pi = OFF_TO_IDX(cur->offset); 2777 e = pi + OFF_TO_IDX(cur->end - cur->start); 2778 for (;; pi = sb->p + SWAP_META_PAGES) { 2779 sb = SWAP_PCTRIE_LOOKUP_GE( 2780 &object->un_pager.swp.swp_blks, pi); 2781 if (sb == NULL || sb->p >= e) 2782 break; 2783 for (i = 0; i < SWAP_META_PAGES; i++) { 2784 if (sb->p + i < e && 2785 sb->d[i] != SWAPBLK_NONE) 2786 count++; 2787 } 2788 } 2789 unlock: 2790 VM_OBJECT_RUNLOCK(object); 2791 } 2792 return (count); 2793 } 2794 2795 /* 2796 * GEOM backend 2797 * 2798 * Swapping onto disk devices. 2799 * 2800 */ 2801 2802 static g_orphan_t swapgeom_orphan; 2803 2804 static struct g_class g_swap_class = { 2805 .name = "SWAP", 2806 .version = G_VERSION, 2807 .orphan = swapgeom_orphan, 2808 }; 2809 2810 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2811 2812 static void 2813 swapgeom_close_ev(void *arg, int flags) 2814 { 2815 struct g_consumer *cp; 2816 2817 cp = arg; 2818 g_access(cp, -1, -1, 0); 2819 g_detach(cp); 2820 g_destroy_consumer(cp); 2821 } 2822 2823 /* 2824 * Add a reference to the g_consumer for an inflight transaction. 2825 */ 2826 static void 2827 swapgeom_acquire(struct g_consumer *cp) 2828 { 2829 2830 mtx_assert(&sw_dev_mtx, MA_OWNED); 2831 cp->index++; 2832 } 2833 2834 /* 2835 * Remove a reference from the g_consumer. Post a close event if all 2836 * references go away, since the function might be called from the 2837 * biodone context. 2838 */ 2839 static void 2840 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2841 { 2842 2843 mtx_assert(&sw_dev_mtx, MA_OWNED); 2844 cp->index--; 2845 if (cp->index == 0) { 2846 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2847 sp->sw_id = NULL; 2848 } 2849 } 2850 2851 static void 2852 swapgeom_done(struct bio *bp2) 2853 { 2854 struct swdevt *sp; 2855 struct buf *bp; 2856 struct g_consumer *cp; 2857 2858 bp = bp2->bio_caller2; 2859 cp = bp2->bio_from; 2860 bp->b_ioflags = bp2->bio_flags; 2861 if (bp2->bio_error) 2862 bp->b_ioflags |= BIO_ERROR; 2863 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2864 bp->b_error = bp2->bio_error; 2865 bp->b_caller1 = NULL; 2866 bufdone(bp); 2867 sp = bp2->bio_caller1; 2868 mtx_lock(&sw_dev_mtx); 2869 swapgeom_release(cp, sp); 2870 mtx_unlock(&sw_dev_mtx); 2871 g_destroy_bio(bp2); 2872 } 2873 2874 static void 2875 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2876 { 2877 struct bio *bio; 2878 struct g_consumer *cp; 2879 2880 mtx_lock(&sw_dev_mtx); 2881 cp = sp->sw_id; 2882 if (cp == NULL) { 2883 mtx_unlock(&sw_dev_mtx); 2884 bp->b_error = ENXIO; 2885 bp->b_ioflags |= BIO_ERROR; 2886 bufdone(bp); 2887 return; 2888 } 2889 swapgeom_acquire(cp); 2890 mtx_unlock(&sw_dev_mtx); 2891 if (bp->b_iocmd == BIO_WRITE) 2892 bio = g_new_bio(); 2893 else 2894 bio = g_alloc_bio(); 2895 if (bio == NULL) { 2896 mtx_lock(&sw_dev_mtx); 2897 swapgeom_release(cp, sp); 2898 mtx_unlock(&sw_dev_mtx); 2899 bp->b_error = ENOMEM; 2900 bp->b_ioflags |= BIO_ERROR; 2901 printf("swap_pager: cannot allocate bio\n"); 2902 bufdone(bp); 2903 return; 2904 } 2905 2906 bp->b_caller1 = bio; 2907 bio->bio_caller1 = sp; 2908 bio->bio_caller2 = bp; 2909 bio->bio_cmd = bp->b_iocmd; 2910 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2911 bio->bio_length = bp->b_bcount; 2912 bio->bio_done = swapgeom_done; 2913 bio->bio_flags |= BIO_SWAP; 2914 if (!buf_mapped(bp)) { 2915 bio->bio_ma = bp->b_pages; 2916 bio->bio_data = unmapped_buf; 2917 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2918 bio->bio_ma_n = bp->b_npages; 2919 bio->bio_flags |= BIO_UNMAPPED; 2920 } else { 2921 bio->bio_data = bp->b_data; 2922 bio->bio_ma = NULL; 2923 } 2924 g_io_request(bio, cp); 2925 return; 2926 } 2927 2928 static void 2929 swapgeom_orphan(struct g_consumer *cp) 2930 { 2931 struct swdevt *sp; 2932 int destroy; 2933 2934 mtx_lock(&sw_dev_mtx); 2935 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2936 if (sp->sw_id == cp) { 2937 sp->sw_flags |= SW_CLOSING; 2938 break; 2939 } 2940 } 2941 /* 2942 * Drop reference we were created with. Do directly since we're in a 2943 * special context where we don't have to queue the call to 2944 * swapgeom_close_ev(). 2945 */ 2946 cp->index--; 2947 destroy = ((sp != NULL) && (cp->index == 0)); 2948 if (destroy) 2949 sp->sw_id = NULL; 2950 mtx_unlock(&sw_dev_mtx); 2951 if (destroy) 2952 swapgeom_close_ev(cp, 0); 2953 } 2954 2955 static void 2956 swapgeom_close(struct thread *td, struct swdevt *sw) 2957 { 2958 struct g_consumer *cp; 2959 2960 mtx_lock(&sw_dev_mtx); 2961 cp = sw->sw_id; 2962 sw->sw_id = NULL; 2963 mtx_unlock(&sw_dev_mtx); 2964 2965 /* 2966 * swapgeom_close() may be called from the biodone context, 2967 * where we cannot perform topology changes. Delegate the 2968 * work to the events thread. 2969 */ 2970 if (cp != NULL) 2971 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2972 } 2973 2974 static int 2975 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2976 { 2977 struct g_provider *pp; 2978 struct g_consumer *cp; 2979 static struct g_geom *gp; 2980 struct swdevt *sp; 2981 u_long nblks; 2982 int error; 2983 2984 pp = g_dev_getprovider(dev); 2985 if (pp == NULL) 2986 return (ENODEV); 2987 mtx_lock(&sw_dev_mtx); 2988 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2989 cp = sp->sw_id; 2990 if (cp != NULL && cp->provider == pp) { 2991 mtx_unlock(&sw_dev_mtx); 2992 return (EBUSY); 2993 } 2994 } 2995 mtx_unlock(&sw_dev_mtx); 2996 if (gp == NULL) 2997 gp = g_new_geomf(&g_swap_class, "swap"); 2998 cp = g_new_consumer(gp); 2999 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 3000 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 3001 g_attach(cp, pp); 3002 /* 3003 * XXX: Every time you think you can improve the margin for 3004 * footshooting, somebody depends on the ability to do so: 3005 * savecore(8) wants to write to our swapdev so we cannot 3006 * set an exclusive count :-( 3007 */ 3008 error = g_access(cp, 1, 1, 0); 3009 if (error != 0) { 3010 g_detach(cp); 3011 g_destroy_consumer(cp); 3012 return (error); 3013 } 3014 nblks = pp->mediasize / DEV_BSIZE; 3015 swaponsomething(vp, cp, nblks, swapgeom_strategy, 3016 swapgeom_close, dev2udev(dev), 3017 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 3018 return (0); 3019 } 3020 3021 static int 3022 swapongeom(struct vnode *vp) 3023 { 3024 int error; 3025 3026 ASSERT_VOP_ELOCKED(vp, "swapongeom"); 3027 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 3028 error = ENOENT; 3029 } else { 3030 g_topology_lock(); 3031 error = swapongeom_locked(vp->v_rdev, vp); 3032 g_topology_unlock(); 3033 } 3034 return (error); 3035 } 3036 3037 /* 3038 * VNODE backend 3039 * 3040 * This is used mainly for network filesystem (read: probably only tested 3041 * with NFS) swapfiles. 3042 * 3043 */ 3044 3045 static void 3046 swapdev_strategy(struct buf *bp, struct swdevt *sp) 3047 { 3048 struct vnode *vp2; 3049 3050 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 3051 3052 vp2 = sp->sw_id; 3053 vhold(vp2); 3054 if (bp->b_iocmd == BIO_WRITE) { 3055 vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); 3056 if (bp->b_bufobj) 3057 bufobj_wdrop(bp->b_bufobj); 3058 bufobj_wref(&vp2->v_bufobj); 3059 } else { 3060 vn_lock(vp2, LK_SHARED | LK_RETRY); 3061 } 3062 if (bp->b_bufobj != &vp2->v_bufobj) 3063 bp->b_bufobj = &vp2->v_bufobj; 3064 bp->b_vp = vp2; 3065 bp->b_iooffset = dbtob(bp->b_blkno); 3066 bstrategy(bp); 3067 VOP_UNLOCK(vp2); 3068 } 3069 3070 static void 3071 swapdev_close(struct thread *td, struct swdevt *sp) 3072 { 3073 struct vnode *vp; 3074 3075 vp = sp->sw_vp; 3076 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3077 VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); 3078 vput(vp); 3079 } 3080 3081 static int 3082 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3083 { 3084 struct swdevt *sp; 3085 int error; 3086 3087 ASSERT_VOP_ELOCKED(vp, "swaponvp"); 3088 if (nblks == 0) 3089 return (ENXIO); 3090 mtx_lock(&sw_dev_mtx); 3091 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3092 if (sp->sw_id == vp) { 3093 mtx_unlock(&sw_dev_mtx); 3094 return (EBUSY); 3095 } 3096 } 3097 mtx_unlock(&sw_dev_mtx); 3098 3099 #ifdef MAC 3100 error = mac_system_check_swapon(td->td_ucred, vp); 3101 if (error == 0) 3102 #endif 3103 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3104 if (error != 0) 3105 return (error); 3106 3107 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3108 NODEV, 0); 3109 return (0); 3110 } 3111 3112 static int 3113 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3114 { 3115 int error, new, n; 3116 3117 new = nsw_wcount_async_max; 3118 error = sysctl_handle_int(oidp, &new, 0, req); 3119 if (error != 0 || req->newptr == NULL) 3120 return (error); 3121 3122 if (new > nswbuf / 2 || new < 1) 3123 return (EINVAL); 3124 3125 mtx_lock(&swbuf_mtx); 3126 while (nsw_wcount_async_max != new) { 3127 /* 3128 * Adjust difference. If the current async count is too low, 3129 * we will need to sqeeze our update slowly in. Sleep with a 3130 * higher priority than getpbuf() to finish faster. 3131 */ 3132 n = new - nsw_wcount_async_max; 3133 if (nsw_wcount_async + n >= 0) { 3134 nsw_wcount_async += n; 3135 nsw_wcount_async_max += n; 3136 wakeup(&nsw_wcount_async); 3137 } else { 3138 nsw_wcount_async_max -= nsw_wcount_async; 3139 nsw_wcount_async = 0; 3140 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3141 "swpsysctl", 0); 3142 } 3143 } 3144 mtx_unlock(&swbuf_mtx); 3145 3146 return (0); 3147 } 3148 3149 static void 3150 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3151 vm_offset_t end) 3152 { 3153 3154 VM_OBJECT_WLOCK(object); 3155 KASSERT((object->flags & OBJ_ANON) == 0, 3156 ("Splittable object with writecount")); 3157 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3158 VM_OBJECT_WUNLOCK(object); 3159 } 3160 3161 static void 3162 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3163 vm_offset_t end) 3164 { 3165 3166 VM_OBJECT_WLOCK(object); 3167 KASSERT((object->flags & OBJ_ANON) == 0, 3168 ("Splittable object with writecount")); 3169 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3170 VM_OBJECT_WUNLOCK(object); 3171 } 3172