1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/bio.h> 78 #include <sys/blist.h> 79 #include <sys/buf.h> 80 #include <sys/conf.h> 81 #include <sys/disk.h> 82 #include <sys/disklabel.h> 83 #include <sys/eventhandler.h> 84 #include <sys/fcntl.h> 85 #include <sys/lock.h> 86 #include <sys/kernel.h> 87 #include <sys/mount.h> 88 #include <sys/namei.h> 89 #include <sys/malloc.h> 90 #include <sys/pctrie.h> 91 #include <sys/priv.h> 92 #include <sys/proc.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/systm.h> 101 #include <sys/sx.h> 102 #include <sys/vmmeter.h> 103 #include <sys/vnode.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static u_long swap_reserved; 156 static u_long swap_total; 157 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 158 159 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD, 0, "VM swap stats"); 160 161 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 162 &swap_reserved, 0, sysctl_page_shift, "A", 163 "Amount of swap storage needed to back all allocated anonymous memory."); 164 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 165 &swap_total, 0, sysctl_page_shift, "A", 166 "Total amount of available swap storage."); 167 168 static int overcommit = 0; 169 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 170 "Configure virtual memory overcommit behavior. See tuning(7) " 171 "for details."); 172 static unsigned long swzone; 173 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 174 "Actual size of swap metadata zone"); 175 static unsigned long swap_maxpages; 176 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 177 "Maximum amount of swap supported"); 178 179 static counter_u64_t swap_free_deferred; 180 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 181 CTLFLAG_RD, &swap_free_deferred, 182 "Number of pages that deferred freeing swap space"); 183 184 static counter_u64_t swap_free_completed; 185 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 186 CTLFLAG_RD, &swap_free_completed, 187 "Number of deferred frees completed"); 188 189 /* bits from overcommit */ 190 #define SWAP_RESERVE_FORCE_ON (1 << 0) 191 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 192 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 193 194 static int 195 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 196 { 197 uint64_t newval; 198 u_long value = *(u_long *)arg1; 199 200 newval = ((uint64_t)value) << PAGE_SHIFT; 201 return (sysctl_handle_64(oidp, &newval, 0, req)); 202 } 203 204 int 205 swap_reserve(vm_ooffset_t incr) 206 { 207 208 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 209 } 210 211 int 212 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 213 { 214 u_long r, s, prev, pincr; 215 int res, error; 216 static int curfail; 217 static struct timeval lastfail; 218 struct uidinfo *uip; 219 220 uip = cred->cr_ruidinfo; 221 222 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 223 (uintmax_t)incr)); 224 225 #ifdef RACCT 226 if (racct_enable) { 227 PROC_LOCK(curproc); 228 error = racct_add(curproc, RACCT_SWAP, incr); 229 PROC_UNLOCK(curproc); 230 if (error != 0) 231 return (0); 232 } 233 #endif 234 235 pincr = atop(incr); 236 res = 0; 237 prev = atomic_fetchadd_long(&swap_reserved, pincr); 238 r = prev + pincr; 239 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 240 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 241 vm_wire_count(); 242 } else 243 s = 0; 244 s += swap_total; 245 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 246 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 247 res = 1; 248 } else { 249 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 250 if (prev < pincr) 251 panic("swap_reserved < incr on overcommit fail"); 252 } 253 if (res) { 254 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 255 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 256 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 257 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 258 res = 0; 259 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 260 if (prev < pincr) 261 panic("uip->ui_vmsize < incr on overcommit fail"); 262 } 263 } 264 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 265 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 266 uip->ui_uid, curproc->p_pid, incr); 267 } 268 269 #ifdef RACCT 270 if (racct_enable && !res) { 271 PROC_LOCK(curproc); 272 racct_sub(curproc, RACCT_SWAP, incr); 273 PROC_UNLOCK(curproc); 274 } 275 #endif 276 277 return (res); 278 } 279 280 void 281 swap_reserve_force(vm_ooffset_t incr) 282 { 283 struct uidinfo *uip; 284 u_long pincr; 285 286 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 287 (uintmax_t)incr)); 288 289 PROC_LOCK(curproc); 290 #ifdef RACCT 291 if (racct_enable) 292 racct_add_force(curproc, RACCT_SWAP, incr); 293 #endif 294 pincr = atop(incr); 295 atomic_add_long(&swap_reserved, pincr); 296 uip = curproc->p_ucred->cr_ruidinfo; 297 atomic_add_long(&uip->ui_vmsize, pincr); 298 PROC_UNLOCK(curproc); 299 } 300 301 void 302 swap_release(vm_ooffset_t decr) 303 { 304 struct ucred *cred; 305 306 PROC_LOCK(curproc); 307 cred = curproc->p_ucred; 308 swap_release_by_cred(decr, cred); 309 PROC_UNLOCK(curproc); 310 } 311 312 void 313 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 314 { 315 u_long prev, pdecr; 316 struct uidinfo *uip; 317 318 uip = cred->cr_ruidinfo; 319 320 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 321 (uintmax_t)decr)); 322 323 pdecr = atop(decr); 324 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 325 if (prev < pdecr) 326 panic("swap_reserved < decr"); 327 328 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 329 if (prev < pdecr) 330 printf("negative vmsize for uid = %d\n", uip->ui_uid); 331 #ifdef RACCT 332 if (racct_enable) 333 racct_sub_cred(cred, RACCT_SWAP, decr); 334 #endif 335 } 336 337 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 338 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 339 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 340 static int nsw_wcount_async; /* limit async write buffers */ 341 static int nsw_wcount_async_max;/* assigned maximum */ 342 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 343 344 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 345 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 346 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 347 "Maximum running async swap ops"); 348 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 349 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 350 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 351 "Swap Fragmentation Info"); 352 353 static struct sx sw_alloc_sx; 354 355 /* 356 * "named" and "unnamed" anon region objects. Try to reduce the overhead 357 * of searching a named list by hashing it just a little. 358 */ 359 360 #define NOBJLISTS 8 361 362 #define NOBJLIST(handle) \ 363 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 364 365 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 366 static uma_zone_t swwbuf_zone; 367 static uma_zone_t swrbuf_zone; 368 static uma_zone_t swblk_zone; 369 static uma_zone_t swpctrie_zone; 370 371 /* 372 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 373 * calls hooked from other parts of the VM system and do not appear here. 374 * (see vm/swap_pager.h). 375 */ 376 static vm_object_t 377 swap_pager_alloc(void *handle, vm_ooffset_t size, 378 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 379 static void swap_pager_dealloc(vm_object_t object); 380 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 381 int *); 382 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 383 int *, pgo_getpages_iodone_t, void *); 384 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 385 static boolean_t 386 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 387 static void swap_pager_init(void); 388 static void swap_pager_unswapped(vm_page_t); 389 static void swap_pager_swapoff(struct swdevt *sp); 390 static void swap_pager_update_writecount(vm_object_t object, 391 vm_offset_t start, vm_offset_t end); 392 static void swap_pager_release_writecount(vm_object_t object, 393 vm_offset_t start, vm_offset_t end); 394 395 struct pagerops swappagerops = { 396 .pgo_init = swap_pager_init, /* early system initialization of pager */ 397 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 398 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 399 .pgo_getpages = swap_pager_getpages, /* pagein */ 400 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 401 .pgo_putpages = swap_pager_putpages, /* pageout */ 402 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 403 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 404 .pgo_update_writecount = swap_pager_update_writecount, 405 .pgo_release_writecount = swap_pager_release_writecount, 406 }; 407 408 /* 409 * swap_*() routines are externally accessible. swp_*() routines are 410 * internal. 411 */ 412 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 413 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 414 415 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 416 "Maximum size of a swap block in pages"); 417 418 static void swp_sizecheck(void); 419 static void swp_pager_async_iodone(struct buf *bp); 420 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 421 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 422 static int swapongeom(struct vnode *); 423 static int swaponvp(struct thread *, struct vnode *, u_long); 424 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 425 426 /* 427 * Swap bitmap functions 428 */ 429 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 430 static daddr_t swp_pager_getswapspace(int *npages); 431 432 /* 433 * Metadata functions 434 */ 435 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 436 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 437 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 438 vm_pindex_t pindex, vm_pindex_t count); 439 static void swp_pager_meta_free_all(vm_object_t); 440 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 441 442 static void 443 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 444 { 445 446 *start = SWAPBLK_NONE; 447 *num = 0; 448 } 449 450 static void 451 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 452 { 453 454 if (*start + *num == addr) { 455 (*num)++; 456 } else { 457 swp_pager_freeswapspace(*start, *num); 458 *start = addr; 459 *num = 1; 460 } 461 } 462 463 static void * 464 swblk_trie_alloc(struct pctrie *ptree) 465 { 466 467 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 468 M_USE_RESERVE : 0))); 469 } 470 471 static void 472 swblk_trie_free(struct pctrie *ptree, void *node) 473 { 474 475 uma_zfree(swpctrie_zone, node); 476 } 477 478 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 479 480 /* 481 * SWP_SIZECHECK() - update swap_pager_full indication 482 * 483 * update the swap_pager_almost_full indication and warn when we are 484 * about to run out of swap space, using lowat/hiwat hysteresis. 485 * 486 * Clear swap_pager_full ( task killing ) indication when lowat is met. 487 * 488 * No restrictions on call 489 * This routine may not block. 490 */ 491 static void 492 swp_sizecheck(void) 493 { 494 495 if (swap_pager_avail < nswap_lowat) { 496 if (swap_pager_almost_full == 0) { 497 printf("swap_pager: out of swap space\n"); 498 swap_pager_almost_full = 1; 499 } 500 } else { 501 swap_pager_full = 0; 502 if (swap_pager_avail > nswap_hiwat) 503 swap_pager_almost_full = 0; 504 } 505 } 506 507 /* 508 * SWAP_PAGER_INIT() - initialize the swap pager! 509 * 510 * Expected to be started from system init. NOTE: This code is run 511 * before much else so be careful what you depend on. Most of the VM 512 * system has yet to be initialized at this point. 513 */ 514 static void 515 swap_pager_init(void) 516 { 517 /* 518 * Initialize object lists 519 */ 520 int i; 521 522 for (i = 0; i < NOBJLISTS; ++i) 523 TAILQ_INIT(&swap_pager_object_list[i]); 524 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 525 sx_init(&sw_alloc_sx, "swspsx"); 526 sx_init(&swdev_syscall_lock, "swsysc"); 527 } 528 529 static void 530 swap_pager_counters(void) 531 { 532 533 swap_free_deferred = counter_u64_alloc(M_WAITOK); 534 swap_free_completed = counter_u64_alloc(M_WAITOK); 535 } 536 SYSINIT(swap_counters, SI_SUB_CPU, SI_ORDER_ANY, swap_pager_counters, NULL); 537 538 /* 539 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 540 * 541 * Expected to be started from pageout process once, prior to entering 542 * its main loop. 543 */ 544 void 545 swap_pager_swap_init(void) 546 { 547 unsigned long n, n2; 548 549 /* 550 * Number of in-transit swap bp operations. Don't 551 * exhaust the pbufs completely. Make sure we 552 * initialize workable values (0 will work for hysteresis 553 * but it isn't very efficient). 554 * 555 * The nsw_cluster_max is constrained by the bp->b_pages[] 556 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 557 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 558 * constrained by the swap device interleave stripe size. 559 * 560 * Currently we hardwire nsw_wcount_async to 4. This limit is 561 * designed to prevent other I/O from having high latencies due to 562 * our pageout I/O. The value 4 works well for one or two active swap 563 * devices but is probably a little low if you have more. Even so, 564 * a higher value would probably generate only a limited improvement 565 * with three or four active swap devices since the system does not 566 * typically have to pageout at extreme bandwidths. We will want 567 * at least 2 per swap devices, and 4 is a pretty good value if you 568 * have one NFS swap device due to the command/ack latency over NFS. 569 * So it all works out pretty well. 570 */ 571 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 572 573 nsw_wcount_async = 4; 574 nsw_wcount_async_max = nsw_wcount_async; 575 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 576 577 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 578 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 579 580 /* 581 * Initialize our zone, taking the user's requested size or 582 * estimating the number we need based on the number of pages 583 * in the system. 584 */ 585 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 586 vm_cnt.v_page_count / 2; 587 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 588 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 589 if (swpctrie_zone == NULL) 590 panic("failed to create swap pctrie zone."); 591 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 592 NULL, NULL, _Alignof(struct swblk) - 1, 0); 593 if (swblk_zone == NULL) 594 panic("failed to create swap blk zone."); 595 n2 = n; 596 do { 597 if (uma_zone_reserve_kva(swblk_zone, n)) 598 break; 599 /* 600 * if the allocation failed, try a zone two thirds the 601 * size of the previous attempt. 602 */ 603 n -= ((n + 2) / 3); 604 } while (n > 0); 605 606 /* 607 * Often uma_zone_reserve_kva() cannot reserve exactly the 608 * requested size. Account for the difference when 609 * calculating swap_maxpages. 610 */ 611 n = uma_zone_get_max(swblk_zone); 612 613 if (n < n2) 614 printf("Swap blk zone entries changed from %lu to %lu.\n", 615 n2, n); 616 /* absolute maximum we can handle assuming 100% efficiency */ 617 swap_maxpages = n * SWAP_META_PAGES; 618 swzone = n * sizeof(struct swblk); 619 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 620 printf("Cannot reserve swap pctrie zone, " 621 "reduce kern.maxswzone.\n"); 622 } 623 624 static vm_object_t 625 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 626 vm_ooffset_t offset) 627 { 628 vm_object_t object; 629 630 if (cred != NULL) { 631 if (!swap_reserve_by_cred(size, cred)) 632 return (NULL); 633 crhold(cred); 634 } 635 636 /* 637 * The un_pager.swp.swp_blks trie is initialized by 638 * vm_object_allocate() to ensure the correct order of 639 * visibility to other threads. 640 */ 641 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 642 PAGE_MASK + size)); 643 644 object->un_pager.swp.writemappings = 0; 645 object->handle = handle; 646 if (cred != NULL) { 647 object->cred = cred; 648 object->charge = size; 649 } 650 return (object); 651 } 652 653 /* 654 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 655 * its metadata structures. 656 * 657 * This routine is called from the mmap and fork code to create a new 658 * OBJT_SWAP object. 659 * 660 * This routine must ensure that no live duplicate is created for 661 * the named object request, which is protected against by 662 * holding the sw_alloc_sx lock in case handle != NULL. 663 */ 664 static vm_object_t 665 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 666 vm_ooffset_t offset, struct ucred *cred) 667 { 668 vm_object_t object; 669 670 if (handle != NULL) { 671 /* 672 * Reference existing named region or allocate new one. There 673 * should not be a race here against swp_pager_meta_build() 674 * as called from vm_page_remove() in regards to the lookup 675 * of the handle. 676 */ 677 sx_xlock(&sw_alloc_sx); 678 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 679 if (object == NULL) { 680 object = swap_pager_alloc_init(handle, cred, size, 681 offset); 682 if (object != NULL) { 683 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 684 object, pager_object_list); 685 } 686 } 687 sx_xunlock(&sw_alloc_sx); 688 } else { 689 object = swap_pager_alloc_init(handle, cred, size, offset); 690 } 691 return (object); 692 } 693 694 /* 695 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 696 * 697 * The swap backing for the object is destroyed. The code is 698 * designed such that we can reinstantiate it later, but this 699 * routine is typically called only when the entire object is 700 * about to be destroyed. 701 * 702 * The object must be locked. 703 */ 704 static void 705 swap_pager_dealloc(vm_object_t object) 706 { 707 708 VM_OBJECT_ASSERT_WLOCKED(object); 709 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 710 711 /* 712 * Remove from list right away so lookups will fail if we block for 713 * pageout completion. 714 */ 715 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 716 VM_OBJECT_WUNLOCK(object); 717 sx_xlock(&sw_alloc_sx); 718 TAILQ_REMOVE(NOBJLIST(object->handle), object, 719 pager_object_list); 720 sx_xunlock(&sw_alloc_sx); 721 VM_OBJECT_WLOCK(object); 722 } 723 724 vm_object_pip_wait(object, "swpdea"); 725 726 /* 727 * Free all remaining metadata. We only bother to free it from 728 * the swap meta data. We do not attempt to free swapblk's still 729 * associated with vm_page_t's for this object. We do not care 730 * if paging is still in progress on some objects. 731 */ 732 swp_pager_meta_free_all(object); 733 object->handle = NULL; 734 object->type = OBJT_DEAD; 735 } 736 737 /************************************************************************ 738 * SWAP PAGER BITMAP ROUTINES * 739 ************************************************************************/ 740 741 /* 742 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 743 * 744 * Allocate swap for up to the requested number of pages. The 745 * starting swap block number (a page index) is returned or 746 * SWAPBLK_NONE if the allocation failed. 747 * 748 * Also has the side effect of advising that somebody made a mistake 749 * when they configured swap and didn't configure enough. 750 * 751 * This routine may not sleep. 752 * 753 * We allocate in round-robin fashion from the configured devices. 754 */ 755 static daddr_t 756 swp_pager_getswapspace(int *io_npages) 757 { 758 daddr_t blk; 759 struct swdevt *sp; 760 int mpages, npages; 761 762 KASSERT(*io_npages >= 1, 763 ("%s: npages not positive", __func__)); 764 blk = SWAPBLK_NONE; 765 mpages = *io_npages; 766 npages = imin(BLIST_MAX_ALLOC, mpages); 767 mtx_lock(&sw_dev_mtx); 768 sp = swdevhd; 769 while (!TAILQ_EMPTY(&swtailq)) { 770 if (sp == NULL) 771 sp = TAILQ_FIRST(&swtailq); 772 if ((sp->sw_flags & SW_CLOSING) == 0) 773 blk = blist_alloc(sp->sw_blist, &npages, mpages); 774 if (blk != SWAPBLK_NONE) 775 break; 776 sp = TAILQ_NEXT(sp, sw_list); 777 if (swdevhd == sp) { 778 if (npages == 1) 779 break; 780 mpages = npages - 1; 781 npages >>= 1; 782 } 783 } 784 if (blk != SWAPBLK_NONE) { 785 *io_npages = npages; 786 blk += sp->sw_first; 787 sp->sw_used += npages; 788 swap_pager_avail -= npages; 789 swp_sizecheck(); 790 swdevhd = TAILQ_NEXT(sp, sw_list); 791 } else { 792 if (swap_pager_full != 2) { 793 printf("swp_pager_getswapspace(%d): failed\n", 794 *io_npages); 795 swap_pager_full = 2; 796 swap_pager_almost_full = 1; 797 } 798 swdevhd = NULL; 799 } 800 mtx_unlock(&sw_dev_mtx); 801 return (blk); 802 } 803 804 static bool 805 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 806 { 807 808 return (blk >= sp->sw_first && blk < sp->sw_end); 809 } 810 811 static void 812 swp_pager_strategy(struct buf *bp) 813 { 814 struct swdevt *sp; 815 816 mtx_lock(&sw_dev_mtx); 817 TAILQ_FOREACH(sp, &swtailq, sw_list) { 818 if (swp_pager_isondev(bp->b_blkno, sp)) { 819 mtx_unlock(&sw_dev_mtx); 820 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 821 unmapped_buf_allowed) { 822 bp->b_data = unmapped_buf; 823 bp->b_offset = 0; 824 } else { 825 pmap_qenter((vm_offset_t)bp->b_data, 826 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 827 } 828 sp->sw_strategy(bp, sp); 829 return; 830 } 831 } 832 panic("Swapdev not found"); 833 } 834 835 836 /* 837 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 838 * 839 * This routine returns the specified swap blocks back to the bitmap. 840 * 841 * This routine may not sleep. 842 */ 843 static void 844 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 845 { 846 struct swdevt *sp; 847 848 if (npages == 0) 849 return; 850 mtx_lock(&sw_dev_mtx); 851 TAILQ_FOREACH(sp, &swtailq, sw_list) { 852 if (swp_pager_isondev(blk, sp)) { 853 sp->sw_used -= npages; 854 /* 855 * If we are attempting to stop swapping on 856 * this device, we don't want to mark any 857 * blocks free lest they be reused. 858 */ 859 if ((sp->sw_flags & SW_CLOSING) == 0) { 860 blist_free(sp->sw_blist, blk - sp->sw_first, 861 npages); 862 swap_pager_avail += npages; 863 swp_sizecheck(); 864 } 865 mtx_unlock(&sw_dev_mtx); 866 return; 867 } 868 } 869 panic("Swapdev not found"); 870 } 871 872 /* 873 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 874 */ 875 static int 876 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 877 { 878 struct sbuf sbuf; 879 struct swdevt *sp; 880 const char *devname; 881 int error; 882 883 error = sysctl_wire_old_buffer(req, 0); 884 if (error != 0) 885 return (error); 886 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 887 mtx_lock(&sw_dev_mtx); 888 TAILQ_FOREACH(sp, &swtailq, sw_list) { 889 if (vn_isdisk(sp->sw_vp, NULL)) 890 devname = devtoname(sp->sw_vp->v_rdev); 891 else 892 devname = "[file]"; 893 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 894 blist_stats(sp->sw_blist, &sbuf); 895 } 896 mtx_unlock(&sw_dev_mtx); 897 error = sbuf_finish(&sbuf); 898 sbuf_delete(&sbuf); 899 return (error); 900 } 901 902 /* 903 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 904 * range within an object. 905 * 906 * This is a globally accessible routine. 907 * 908 * This routine removes swapblk assignments from swap metadata. 909 * 910 * The external callers of this routine typically have already destroyed 911 * or renamed vm_page_t's associated with this range in the object so 912 * we should be ok. 913 * 914 * The object must be locked. 915 */ 916 void 917 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 918 { 919 920 swp_pager_meta_free(object, start, size); 921 } 922 923 /* 924 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 925 * 926 * Assigns swap blocks to the specified range within the object. The 927 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 928 * 929 * Returns 0 on success, -1 on failure. 930 */ 931 int 932 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 933 { 934 daddr_t addr, blk, n_free, s_free; 935 int i, j, n; 936 937 swp_pager_init_freerange(&s_free, &n_free); 938 VM_OBJECT_WLOCK(object); 939 for (i = 0; i < size; i += n) { 940 n = size - i; 941 blk = swp_pager_getswapspace(&n); 942 if (blk == SWAPBLK_NONE) { 943 swp_pager_meta_free(object, start, i); 944 VM_OBJECT_WUNLOCK(object); 945 return (-1); 946 } 947 for (j = 0; j < n; ++j) { 948 addr = swp_pager_meta_build(object, 949 start + i + j, blk + j); 950 if (addr != SWAPBLK_NONE) 951 swp_pager_update_freerange(&s_free, &n_free, 952 addr); 953 } 954 } 955 swp_pager_freeswapspace(s_free, n_free); 956 VM_OBJECT_WUNLOCK(object); 957 return (0); 958 } 959 960 static bool 961 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 962 vm_pindex_t pindex, daddr_t addr) 963 { 964 daddr_t dstaddr; 965 966 KASSERT(srcobject->type == OBJT_SWAP, 967 ("%s: Srcobject not swappable", __func__)); 968 if (dstobject->type == OBJT_SWAP && 969 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 970 /* Caller should destroy the source block. */ 971 return (false); 972 } 973 974 /* 975 * Destination has no swapblk and is not resident, transfer source. 976 * swp_pager_meta_build() can sleep. 977 */ 978 VM_OBJECT_WUNLOCK(srcobject); 979 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 980 KASSERT(dstaddr == SWAPBLK_NONE, 981 ("Unexpected destination swapblk")); 982 VM_OBJECT_WLOCK(srcobject); 983 984 return (true); 985 } 986 987 /* 988 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 989 * and destroy the source. 990 * 991 * Copy any valid swapblks from the source to the destination. In 992 * cases where both the source and destination have a valid swapblk, 993 * we keep the destination's. 994 * 995 * This routine is allowed to sleep. It may sleep allocating metadata 996 * indirectly through swp_pager_meta_build(). 997 * 998 * The source object contains no vm_page_t's (which is just as well) 999 * 1000 * The source object is of type OBJT_SWAP. 1001 * 1002 * The source and destination objects must be locked. 1003 * Both object locks may temporarily be released. 1004 */ 1005 void 1006 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1007 vm_pindex_t offset, int destroysource) 1008 { 1009 1010 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1011 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1012 1013 /* 1014 * If destroysource is set, we remove the source object from the 1015 * swap_pager internal queue now. 1016 */ 1017 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1018 srcobject->handle != NULL) { 1019 VM_OBJECT_WUNLOCK(srcobject); 1020 VM_OBJECT_WUNLOCK(dstobject); 1021 sx_xlock(&sw_alloc_sx); 1022 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1023 pager_object_list); 1024 sx_xunlock(&sw_alloc_sx); 1025 VM_OBJECT_WLOCK(dstobject); 1026 VM_OBJECT_WLOCK(srcobject); 1027 } 1028 1029 /* 1030 * Transfer source to destination. 1031 */ 1032 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1033 1034 /* 1035 * Free left over swap blocks in source. 1036 * 1037 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1038 * double-remove the object from the swap queues. 1039 */ 1040 if (destroysource) { 1041 swp_pager_meta_free_all(srcobject); 1042 /* 1043 * Reverting the type is not necessary, the caller is going 1044 * to destroy srcobject directly, but I'm doing it here 1045 * for consistency since we've removed the object from its 1046 * queues. 1047 */ 1048 srcobject->type = OBJT_DEFAULT; 1049 } 1050 } 1051 1052 /* 1053 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1054 * the requested page. 1055 * 1056 * We determine whether good backing store exists for the requested 1057 * page and return TRUE if it does, FALSE if it doesn't. 1058 * 1059 * If TRUE, we also try to determine how much valid, contiguous backing 1060 * store exists before and after the requested page. 1061 */ 1062 static boolean_t 1063 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1064 int *after) 1065 { 1066 daddr_t blk, blk0; 1067 int i; 1068 1069 VM_OBJECT_ASSERT_LOCKED(object); 1070 KASSERT(object->type == OBJT_SWAP, 1071 ("%s: object not swappable", __func__)); 1072 1073 /* 1074 * do we have good backing store at the requested index ? 1075 */ 1076 blk0 = swp_pager_meta_lookup(object, pindex); 1077 if (blk0 == SWAPBLK_NONE) { 1078 if (before) 1079 *before = 0; 1080 if (after) 1081 *after = 0; 1082 return (FALSE); 1083 } 1084 1085 /* 1086 * find backwards-looking contiguous good backing store 1087 */ 1088 if (before != NULL) { 1089 for (i = 1; i < SWB_NPAGES; i++) { 1090 if (i > pindex) 1091 break; 1092 blk = swp_pager_meta_lookup(object, pindex - i); 1093 if (blk != blk0 - i) 1094 break; 1095 } 1096 *before = i - 1; 1097 } 1098 1099 /* 1100 * find forward-looking contiguous good backing store 1101 */ 1102 if (after != NULL) { 1103 for (i = 1; i < SWB_NPAGES; i++) { 1104 blk = swp_pager_meta_lookup(object, pindex + i); 1105 if (blk != blk0 + i) 1106 break; 1107 } 1108 *after = i - 1; 1109 } 1110 return (TRUE); 1111 } 1112 1113 /* 1114 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1115 * 1116 * This removes any associated swap backing store, whether valid or 1117 * not, from the page. 1118 * 1119 * This routine is typically called when a page is made dirty, at 1120 * which point any associated swap can be freed. MADV_FREE also 1121 * calls us in a special-case situation 1122 * 1123 * NOTE!!! If the page is clean and the swap was valid, the caller 1124 * should make the page dirty before calling this routine. This routine 1125 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1126 * depends on it. 1127 * 1128 * This routine may not sleep. 1129 * 1130 * The object containing the page may be locked. 1131 */ 1132 static void 1133 swap_pager_unswapped(vm_page_t m) 1134 { 1135 struct swblk *sb; 1136 vm_object_t obj; 1137 1138 /* 1139 * Handle enqueing deferred frees first. If we do not have the 1140 * object lock we wait for the page daemon to clear the space. 1141 */ 1142 obj = m->object; 1143 if (!VM_OBJECT_WOWNED(obj)) { 1144 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1145 /* 1146 * The caller is responsible for synchronization but we 1147 * will harmlessly handle races. This is typically provided 1148 * by only calling unswapped() when a page transitions from 1149 * clean to dirty. 1150 */ 1151 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1152 PGA_SWAP_SPACE) { 1153 vm_page_aflag_set(m, PGA_SWAP_FREE); 1154 counter_u64_add(swap_free_deferred, 1); 1155 } 1156 return; 1157 } 1158 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1159 counter_u64_add(swap_free_completed, 1); 1160 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1161 1162 /* 1163 * The meta data only exists if the object is OBJT_SWAP 1164 * and even then might not be allocated yet. 1165 */ 1166 KASSERT(m->object->type == OBJT_SWAP, 1167 ("Free object not swappable")); 1168 1169 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1170 rounddown(m->pindex, SWAP_META_PAGES)); 1171 if (sb == NULL) 1172 return; 1173 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1174 return; 1175 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1176 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1177 swp_pager_free_empty_swblk(m->object, sb); 1178 } 1179 1180 /* 1181 * swap_pager_getpages() - bring pages in from swap 1182 * 1183 * Attempt to page in the pages in array "ma" of length "count". The 1184 * caller may optionally specify that additional pages preceding and 1185 * succeeding the specified range be paged in. The number of such pages 1186 * is returned in the "rbehind" and "rahead" parameters, and they will 1187 * be in the inactive queue upon return. 1188 * 1189 * The pages in "ma" must be busied and will remain busied upon return. 1190 */ 1191 static int 1192 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1193 int *rbehind, int *rahead) 1194 { 1195 struct buf *bp; 1196 vm_page_t bm, mpred, msucc, p; 1197 vm_pindex_t pindex; 1198 daddr_t blk; 1199 int i, maxahead, maxbehind, reqcount; 1200 1201 VM_OBJECT_ASSERT_WLOCKED(object); 1202 reqcount = count; 1203 1204 KASSERT(object->type == OBJT_SWAP, 1205 ("%s: object not swappable", __func__)); 1206 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1207 VM_OBJECT_WUNLOCK(object); 1208 return (VM_PAGER_FAIL); 1209 } 1210 1211 KASSERT(reqcount - 1 <= maxahead, 1212 ("page count %d extends beyond swap block", reqcount)); 1213 1214 /* 1215 * Do not transfer any pages other than those that are xbusied 1216 * when running during a split or collapse operation. This 1217 * prevents clustering from re-creating pages which are being 1218 * moved into another object. 1219 */ 1220 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1221 maxahead = reqcount - 1; 1222 maxbehind = 0; 1223 } 1224 1225 /* 1226 * Clip the readahead and readbehind ranges to exclude resident pages. 1227 */ 1228 if (rahead != NULL) { 1229 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1230 pindex = ma[reqcount - 1]->pindex; 1231 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1232 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1233 *rahead = msucc->pindex - pindex - 1; 1234 } 1235 if (rbehind != NULL) { 1236 *rbehind = imin(*rbehind, maxbehind); 1237 pindex = ma[0]->pindex; 1238 mpred = TAILQ_PREV(ma[0], pglist, listq); 1239 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1240 *rbehind = pindex - mpred->pindex - 1; 1241 } 1242 1243 bm = ma[0]; 1244 for (i = 0; i < count; i++) 1245 ma[i]->oflags |= VPO_SWAPINPROG; 1246 1247 /* 1248 * Allocate readahead and readbehind pages. 1249 */ 1250 if (rbehind != NULL) { 1251 for (i = 1; i <= *rbehind; i++) { 1252 p = vm_page_alloc(object, ma[0]->pindex - i, 1253 VM_ALLOC_NORMAL); 1254 if (p == NULL) 1255 break; 1256 p->oflags |= VPO_SWAPINPROG; 1257 bm = p; 1258 } 1259 *rbehind = i - 1; 1260 } 1261 if (rahead != NULL) { 1262 for (i = 0; i < *rahead; i++) { 1263 p = vm_page_alloc(object, 1264 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1265 if (p == NULL) 1266 break; 1267 p->oflags |= VPO_SWAPINPROG; 1268 } 1269 *rahead = i; 1270 } 1271 if (rbehind != NULL) 1272 count += *rbehind; 1273 if (rahead != NULL) 1274 count += *rahead; 1275 1276 vm_object_pip_add(object, count); 1277 1278 pindex = bm->pindex; 1279 blk = swp_pager_meta_lookup(object, pindex); 1280 KASSERT(blk != SWAPBLK_NONE, 1281 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1282 1283 VM_OBJECT_WUNLOCK(object); 1284 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1285 /* Pages cannot leave the object while busy. */ 1286 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1287 MPASS(p->pindex == bm->pindex + i); 1288 bp->b_pages[i] = p; 1289 } 1290 1291 bp->b_flags |= B_PAGING; 1292 bp->b_iocmd = BIO_READ; 1293 bp->b_iodone = swp_pager_async_iodone; 1294 bp->b_rcred = crhold(thread0.td_ucred); 1295 bp->b_wcred = crhold(thread0.td_ucred); 1296 bp->b_blkno = blk; 1297 bp->b_bcount = PAGE_SIZE * count; 1298 bp->b_bufsize = PAGE_SIZE * count; 1299 bp->b_npages = count; 1300 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1301 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1302 1303 VM_CNT_INC(v_swapin); 1304 VM_CNT_ADD(v_swappgsin, count); 1305 1306 /* 1307 * perform the I/O. NOTE!!! bp cannot be considered valid after 1308 * this point because we automatically release it on completion. 1309 * Instead, we look at the one page we are interested in which we 1310 * still hold a lock on even through the I/O completion. 1311 * 1312 * The other pages in our ma[] array are also released on completion, 1313 * so we cannot assume they are valid anymore either. 1314 * 1315 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1316 */ 1317 BUF_KERNPROC(bp); 1318 swp_pager_strategy(bp); 1319 1320 /* 1321 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1322 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1323 * is set in the metadata for each page in the request. 1324 */ 1325 VM_OBJECT_WLOCK(object); 1326 /* This could be implemented more efficiently with aflags */ 1327 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1328 ma[0]->oflags |= VPO_SWAPSLEEP; 1329 VM_CNT_INC(v_intrans); 1330 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1331 "swread", hz * 20)) { 1332 printf( 1333 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1334 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1335 } 1336 } 1337 VM_OBJECT_WUNLOCK(object); 1338 1339 /* 1340 * If we had an unrecoverable read error pages will not be valid. 1341 */ 1342 for (i = 0; i < reqcount; i++) 1343 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1344 return (VM_PAGER_ERROR); 1345 1346 return (VM_PAGER_OK); 1347 1348 /* 1349 * A final note: in a low swap situation, we cannot deallocate swap 1350 * and mark a page dirty here because the caller is likely to mark 1351 * the page clean when we return, causing the page to possibly revert 1352 * to all-zero's later. 1353 */ 1354 } 1355 1356 static int 1357 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1358 int *rbehind, int *rahead) 1359 { 1360 1361 VM_OBJECT_WLOCK(object); 1362 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1363 } 1364 1365 /* 1366 * swap_pager_getpages_async(): 1367 * 1368 * Right now this is emulation of asynchronous operation on top of 1369 * swap_pager_getpages(). 1370 */ 1371 static int 1372 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1373 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1374 { 1375 int r, error; 1376 1377 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1378 switch (r) { 1379 case VM_PAGER_OK: 1380 error = 0; 1381 break; 1382 case VM_PAGER_ERROR: 1383 error = EIO; 1384 break; 1385 case VM_PAGER_FAIL: 1386 error = EINVAL; 1387 break; 1388 default: 1389 panic("unhandled swap_pager_getpages() error %d", r); 1390 } 1391 (iodone)(arg, ma, count, error); 1392 1393 return (r); 1394 } 1395 1396 /* 1397 * swap_pager_putpages: 1398 * 1399 * Assign swap (if necessary) and initiate I/O on the specified pages. 1400 * 1401 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1402 * are automatically converted to SWAP objects. 1403 * 1404 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1405 * vm_page reservation system coupled with properly written VFS devices 1406 * should ensure that no low-memory deadlock occurs. This is an area 1407 * which needs work. 1408 * 1409 * The parent has N vm_object_pip_add() references prior to 1410 * calling us and will remove references for rtvals[] that are 1411 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1412 * completion. 1413 * 1414 * The parent has soft-busy'd the pages it passes us and will unbusy 1415 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1416 * We need to unbusy the rest on I/O completion. 1417 */ 1418 static void 1419 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1420 int flags, int *rtvals) 1421 { 1422 struct buf *bp; 1423 daddr_t addr, blk, n_free, s_free; 1424 vm_page_t mreq; 1425 int i, j, n; 1426 bool async; 1427 1428 KASSERT(count == 0 || ma[0]->object == object, 1429 ("%s: object mismatch %p/%p", 1430 __func__, object, ma[0]->object)); 1431 1432 /* 1433 * Step 1 1434 * 1435 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1436 */ 1437 if (object->type != OBJT_SWAP) { 1438 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1439 KASSERT(addr == SWAPBLK_NONE, 1440 ("unexpected object swap block")); 1441 } 1442 VM_OBJECT_WUNLOCK(object); 1443 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1444 swp_pager_init_freerange(&s_free, &n_free); 1445 1446 /* 1447 * Step 2 1448 * 1449 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1450 * The page is left dirty until the pageout operation completes 1451 * successfully. 1452 */ 1453 for (i = 0; i < count; i += n) { 1454 /* Maximum I/O size is limited by maximum swap block size. */ 1455 n = min(count - i, nsw_cluster_max); 1456 1457 if (async) { 1458 mtx_lock(&swbuf_mtx); 1459 while (nsw_wcount_async == 0) 1460 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1461 "swbufa", 0); 1462 nsw_wcount_async--; 1463 mtx_unlock(&swbuf_mtx); 1464 } 1465 1466 /* Get a block of swap of size up to size n. */ 1467 VM_OBJECT_WLOCK(object); 1468 blk = swp_pager_getswapspace(&n); 1469 if (blk == SWAPBLK_NONE) { 1470 VM_OBJECT_WUNLOCK(object); 1471 mtx_lock(&swbuf_mtx); 1472 if (++nsw_wcount_async == 1) 1473 wakeup(&nsw_wcount_async); 1474 mtx_unlock(&swbuf_mtx); 1475 for (j = 0; j < n; ++j) 1476 rtvals[i + j] = VM_PAGER_FAIL; 1477 continue; 1478 } 1479 for (j = 0; j < n; ++j) { 1480 mreq = ma[i + j]; 1481 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1482 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1483 blk + j); 1484 if (addr != SWAPBLK_NONE) 1485 swp_pager_update_freerange(&s_free, &n_free, 1486 addr); 1487 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1488 mreq->oflags |= VPO_SWAPINPROG; 1489 } 1490 VM_OBJECT_WUNLOCK(object); 1491 1492 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1493 if (async) 1494 bp->b_flags = B_ASYNC; 1495 bp->b_flags |= B_PAGING; 1496 bp->b_iocmd = BIO_WRITE; 1497 1498 bp->b_rcred = crhold(thread0.td_ucred); 1499 bp->b_wcred = crhold(thread0.td_ucred); 1500 bp->b_bcount = PAGE_SIZE * n; 1501 bp->b_bufsize = PAGE_SIZE * n; 1502 bp->b_blkno = blk; 1503 for (j = 0; j < n; j++) 1504 bp->b_pages[j] = ma[i + j]; 1505 bp->b_npages = n; 1506 1507 /* 1508 * Must set dirty range for NFS to work. 1509 */ 1510 bp->b_dirtyoff = 0; 1511 bp->b_dirtyend = bp->b_bcount; 1512 1513 VM_CNT_INC(v_swapout); 1514 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1515 1516 /* 1517 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1518 * can call the async completion routine at the end of a 1519 * synchronous I/O operation. Otherwise, our caller would 1520 * perform duplicate unbusy and wakeup operations on the page 1521 * and object, respectively. 1522 */ 1523 for (j = 0; j < n; j++) 1524 rtvals[i + j] = VM_PAGER_PEND; 1525 1526 /* 1527 * asynchronous 1528 * 1529 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1530 */ 1531 if (async) { 1532 bp->b_iodone = swp_pager_async_iodone; 1533 BUF_KERNPROC(bp); 1534 swp_pager_strategy(bp); 1535 continue; 1536 } 1537 1538 /* 1539 * synchronous 1540 * 1541 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1542 */ 1543 bp->b_iodone = bdone; 1544 swp_pager_strategy(bp); 1545 1546 /* 1547 * Wait for the sync I/O to complete. 1548 */ 1549 bwait(bp, PVM, "swwrt"); 1550 1551 /* 1552 * Now that we are through with the bp, we can call the 1553 * normal async completion, which frees everything up. 1554 */ 1555 swp_pager_async_iodone(bp); 1556 } 1557 swp_pager_freeswapspace(s_free, n_free); 1558 VM_OBJECT_WLOCK(object); 1559 } 1560 1561 /* 1562 * swp_pager_async_iodone: 1563 * 1564 * Completion routine for asynchronous reads and writes from/to swap. 1565 * Also called manually by synchronous code to finish up a bp. 1566 * 1567 * This routine may not sleep. 1568 */ 1569 static void 1570 swp_pager_async_iodone(struct buf *bp) 1571 { 1572 int i; 1573 vm_object_t object = NULL; 1574 1575 /* 1576 * Report error - unless we ran out of memory, in which case 1577 * we've already logged it in swapgeom_strategy(). 1578 */ 1579 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1580 printf( 1581 "swap_pager: I/O error - %s failed; blkno %ld," 1582 "size %ld, error %d\n", 1583 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1584 (long)bp->b_blkno, 1585 (long)bp->b_bcount, 1586 bp->b_error 1587 ); 1588 } 1589 1590 /* 1591 * remove the mapping for kernel virtual 1592 */ 1593 if (buf_mapped(bp)) 1594 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1595 else 1596 bp->b_data = bp->b_kvabase; 1597 1598 if (bp->b_npages) { 1599 object = bp->b_pages[0]->object; 1600 VM_OBJECT_WLOCK(object); 1601 } 1602 1603 /* 1604 * cleanup pages. If an error occurs writing to swap, we are in 1605 * very serious trouble. If it happens to be a disk error, though, 1606 * we may be able to recover by reassigning the swap later on. So 1607 * in this case we remove the m->swapblk assignment for the page 1608 * but do not free it in the rlist. The errornous block(s) are thus 1609 * never reallocated as swap. Redirty the page and continue. 1610 */ 1611 for (i = 0; i < bp->b_npages; ++i) { 1612 vm_page_t m = bp->b_pages[i]; 1613 1614 m->oflags &= ~VPO_SWAPINPROG; 1615 if (m->oflags & VPO_SWAPSLEEP) { 1616 m->oflags &= ~VPO_SWAPSLEEP; 1617 wakeup(&object->handle); 1618 } 1619 1620 /* We always have space after I/O, successful or not. */ 1621 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1622 1623 if (bp->b_ioflags & BIO_ERROR) { 1624 /* 1625 * If an error occurs I'd love to throw the swapblk 1626 * away without freeing it back to swapspace, so it 1627 * can never be used again. But I can't from an 1628 * interrupt. 1629 */ 1630 if (bp->b_iocmd == BIO_READ) { 1631 /* 1632 * NOTE: for reads, m->dirty will probably 1633 * be overridden by the original caller of 1634 * getpages so don't play cute tricks here. 1635 */ 1636 vm_page_invalid(m); 1637 } else { 1638 /* 1639 * If a write error occurs, reactivate page 1640 * so it doesn't clog the inactive list, 1641 * then finish the I/O. 1642 */ 1643 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1644 1645 /* PQ_UNSWAPPABLE? */ 1646 vm_page_activate(m); 1647 vm_page_sunbusy(m); 1648 } 1649 } else if (bp->b_iocmd == BIO_READ) { 1650 /* 1651 * NOTE: for reads, m->dirty will probably be 1652 * overridden by the original caller of getpages so 1653 * we cannot set them in order to free the underlying 1654 * swap in a low-swap situation. I don't think we'd 1655 * want to do that anyway, but it was an optimization 1656 * that existed in the old swapper for a time before 1657 * it got ripped out due to precisely this problem. 1658 */ 1659 KASSERT(!pmap_page_is_mapped(m), 1660 ("swp_pager_async_iodone: page %p is mapped", m)); 1661 KASSERT(m->dirty == 0, 1662 ("swp_pager_async_iodone: page %p is dirty", m)); 1663 1664 vm_page_valid(m); 1665 if (i < bp->b_pgbefore || 1666 i >= bp->b_npages - bp->b_pgafter) 1667 vm_page_readahead_finish(m); 1668 } else { 1669 /* 1670 * For write success, clear the dirty 1671 * status, then finish the I/O ( which decrements the 1672 * busy count and possibly wakes waiter's up ). 1673 * A page is only written to swap after a period of 1674 * inactivity. Therefore, we do not expect it to be 1675 * reused. 1676 */ 1677 KASSERT(!pmap_page_is_write_mapped(m), 1678 ("swp_pager_async_iodone: page %p is not write" 1679 " protected", m)); 1680 vm_page_undirty(m); 1681 vm_page_deactivate_noreuse(m); 1682 vm_page_sunbusy(m); 1683 } 1684 } 1685 1686 /* 1687 * adjust pip. NOTE: the original parent may still have its own 1688 * pip refs on the object. 1689 */ 1690 if (object != NULL) { 1691 vm_object_pip_wakeupn(object, bp->b_npages); 1692 VM_OBJECT_WUNLOCK(object); 1693 } 1694 1695 /* 1696 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1697 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1698 * trigger a KASSERT in relpbuf(). 1699 */ 1700 if (bp->b_vp) { 1701 bp->b_vp = NULL; 1702 bp->b_bufobj = NULL; 1703 } 1704 /* 1705 * release the physical I/O buffer 1706 */ 1707 if (bp->b_flags & B_ASYNC) { 1708 mtx_lock(&swbuf_mtx); 1709 if (++nsw_wcount_async == 1) 1710 wakeup(&nsw_wcount_async); 1711 mtx_unlock(&swbuf_mtx); 1712 } 1713 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1714 } 1715 1716 int 1717 swap_pager_nswapdev(void) 1718 { 1719 1720 return (nswapdev); 1721 } 1722 1723 static void 1724 swp_pager_force_dirty(vm_page_t m) 1725 { 1726 1727 vm_page_dirty(m); 1728 swap_pager_unswapped(m); 1729 vm_page_launder(m); 1730 } 1731 1732 /* 1733 * swap_pager_swapoff_object: 1734 * 1735 * Page in all of the pages that have been paged out for an object 1736 * to a swap device. 1737 */ 1738 static void 1739 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1740 { 1741 struct swblk *sb; 1742 vm_page_t m; 1743 vm_pindex_t pi; 1744 daddr_t blk; 1745 int i, nv, rahead, rv; 1746 1747 KASSERT(object->type == OBJT_SWAP, 1748 ("%s: Object not swappable", __func__)); 1749 1750 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1751 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1752 if ((object->flags & OBJ_DEAD) != 0) { 1753 /* 1754 * Make sure that pending writes finish before 1755 * returning. 1756 */ 1757 vm_object_pip_wait(object, "swpoff"); 1758 swp_pager_meta_free_all(object); 1759 break; 1760 } 1761 for (i = 0; i < SWAP_META_PAGES; i++) { 1762 /* 1763 * Count the number of contiguous valid blocks. 1764 */ 1765 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1766 blk = sb->d[i + nv]; 1767 if (!swp_pager_isondev(blk, sp) || 1768 blk == SWAPBLK_NONE) 1769 break; 1770 } 1771 if (nv == 0) 1772 continue; 1773 1774 /* 1775 * Look for a page corresponding to the first 1776 * valid block and ensure that any pending paging 1777 * operations on it are complete. If the page is valid, 1778 * mark it dirty and free the swap block. Try to batch 1779 * this operation since it may cause sp to be freed, 1780 * meaning that we must restart the scan. Avoid busying 1781 * valid pages since we may block forever on kernel 1782 * stack pages. 1783 */ 1784 m = vm_page_lookup(object, sb->p + i); 1785 if (m == NULL) { 1786 m = vm_page_alloc(object, sb->p + i, 1787 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1788 if (m == NULL) 1789 break; 1790 } else { 1791 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1792 m->oflags |= VPO_SWAPSLEEP; 1793 VM_OBJECT_SLEEP(object, &object->handle, 1794 PSWP, "swpoff", 0); 1795 break; 1796 } 1797 if (vm_page_all_valid(m)) { 1798 do { 1799 swp_pager_force_dirty(m); 1800 } while (--nv > 0 && 1801 (m = vm_page_next(m)) != NULL && 1802 vm_page_all_valid(m) && 1803 (m->oflags & VPO_SWAPINPROG) == 0); 1804 break; 1805 } 1806 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1807 break; 1808 } 1809 1810 vm_object_pip_add(object, 1); 1811 rahead = SWAP_META_PAGES; 1812 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1813 &rahead); 1814 if (rv != VM_PAGER_OK) 1815 panic("%s: read from swap failed: %d", 1816 __func__, rv); 1817 vm_object_pip_wakeupn(object, 1); 1818 VM_OBJECT_WLOCK(object); 1819 vm_page_xunbusy(m); 1820 1821 /* 1822 * The object lock was dropped so we must restart the 1823 * scan of this swap block. Pages paged in during this 1824 * iteration will be marked dirty in a future iteration. 1825 */ 1826 break; 1827 } 1828 if (i == SWAP_META_PAGES) 1829 pi = sb->p + SWAP_META_PAGES; 1830 } 1831 } 1832 1833 /* 1834 * swap_pager_swapoff: 1835 * 1836 * Page in all of the pages that have been paged out to the 1837 * given device. The corresponding blocks in the bitmap must be 1838 * marked as allocated and the device must be flagged SW_CLOSING. 1839 * There may be no processes swapped out to the device. 1840 * 1841 * This routine may block. 1842 */ 1843 static void 1844 swap_pager_swapoff(struct swdevt *sp) 1845 { 1846 vm_object_t object; 1847 int retries; 1848 1849 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1850 1851 retries = 0; 1852 full_rescan: 1853 mtx_lock(&vm_object_list_mtx); 1854 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1855 if (object->type != OBJT_SWAP) 1856 continue; 1857 mtx_unlock(&vm_object_list_mtx); 1858 /* Depends on type-stability. */ 1859 VM_OBJECT_WLOCK(object); 1860 1861 /* 1862 * Dead objects are eventually terminated on their own. 1863 */ 1864 if ((object->flags & OBJ_DEAD) != 0) 1865 goto next_obj; 1866 1867 /* 1868 * Sync with fences placed after pctrie 1869 * initialization. We must not access pctrie below 1870 * unless we checked that our object is swap and not 1871 * dead. 1872 */ 1873 atomic_thread_fence_acq(); 1874 if (object->type != OBJT_SWAP) 1875 goto next_obj; 1876 1877 swap_pager_swapoff_object(sp, object); 1878 next_obj: 1879 VM_OBJECT_WUNLOCK(object); 1880 mtx_lock(&vm_object_list_mtx); 1881 } 1882 mtx_unlock(&vm_object_list_mtx); 1883 1884 if (sp->sw_used) { 1885 /* 1886 * Objects may be locked or paging to the device being 1887 * removed, so we will miss their pages and need to 1888 * make another pass. We have marked this device as 1889 * SW_CLOSING, so the activity should finish soon. 1890 */ 1891 retries++; 1892 if (retries > 100) { 1893 panic("swapoff: failed to locate %d swap blocks", 1894 sp->sw_used); 1895 } 1896 pause("swpoff", hz / 20); 1897 goto full_rescan; 1898 } 1899 EVENTHANDLER_INVOKE(swapoff, sp); 1900 } 1901 1902 /************************************************************************ 1903 * SWAP META DATA * 1904 ************************************************************************ 1905 * 1906 * These routines manipulate the swap metadata stored in the 1907 * OBJT_SWAP object. 1908 * 1909 * Swap metadata is implemented with a global hash and not directly 1910 * linked into the object. Instead the object simply contains 1911 * appropriate tracking counters. 1912 */ 1913 1914 /* 1915 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1916 */ 1917 static bool 1918 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1919 { 1920 int i; 1921 1922 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1923 for (i = start; i < limit; i++) { 1924 if (sb->d[i] != SWAPBLK_NONE) 1925 return (false); 1926 } 1927 return (true); 1928 } 1929 1930 /* 1931 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1932 * 1933 * Nothing is done if the block is still in use. 1934 */ 1935 static void 1936 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1937 { 1938 1939 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1940 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1941 uma_zfree(swblk_zone, sb); 1942 } 1943 } 1944 1945 /* 1946 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1947 * 1948 * We first convert the object to a swap object if it is a default 1949 * object. 1950 * 1951 * The specified swapblk is added to the object's swap metadata. If 1952 * the swapblk is not valid, it is freed instead. Any previously 1953 * assigned swapblk is returned. 1954 */ 1955 static daddr_t 1956 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1957 { 1958 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1959 struct swblk *sb, *sb1; 1960 vm_pindex_t modpi, rdpi; 1961 daddr_t prev_swapblk; 1962 int error, i; 1963 1964 VM_OBJECT_ASSERT_WLOCKED(object); 1965 1966 /* 1967 * Convert default object to swap object if necessary 1968 */ 1969 if (object->type != OBJT_SWAP) { 1970 pctrie_init(&object->un_pager.swp.swp_blks); 1971 1972 /* 1973 * Ensure that swap_pager_swapoff()'s iteration over 1974 * object_list does not see a garbage pctrie. 1975 */ 1976 atomic_thread_fence_rel(); 1977 1978 object->type = OBJT_SWAP; 1979 object->un_pager.swp.writemappings = 0; 1980 KASSERT((object->flags & OBJ_ANON) != 0 || 1981 object->handle == NULL, 1982 ("default pager %p with handle %p", 1983 object, object->handle)); 1984 } 1985 1986 rdpi = rounddown(pindex, SWAP_META_PAGES); 1987 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1988 if (sb == NULL) { 1989 if (swapblk == SWAPBLK_NONE) 1990 return (SWAPBLK_NONE); 1991 for (;;) { 1992 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1993 pageproc ? M_USE_RESERVE : 0)); 1994 if (sb != NULL) { 1995 sb->p = rdpi; 1996 for (i = 0; i < SWAP_META_PAGES; i++) 1997 sb->d[i] = SWAPBLK_NONE; 1998 if (atomic_cmpset_int(&swblk_zone_exhausted, 1999 1, 0)) 2000 printf("swblk zone ok\n"); 2001 break; 2002 } 2003 VM_OBJECT_WUNLOCK(object); 2004 if (uma_zone_exhausted(swblk_zone)) { 2005 if (atomic_cmpset_int(&swblk_zone_exhausted, 2006 0, 1)) 2007 printf("swap blk zone exhausted, " 2008 "increase kern.maxswzone\n"); 2009 vm_pageout_oom(VM_OOM_SWAPZ); 2010 pause("swzonxb", 10); 2011 } else 2012 uma_zwait(swblk_zone); 2013 VM_OBJECT_WLOCK(object); 2014 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2015 rdpi); 2016 if (sb != NULL) 2017 /* 2018 * Somebody swapped out a nearby page, 2019 * allocating swblk at the rdpi index, 2020 * while we dropped the object lock. 2021 */ 2022 goto allocated; 2023 } 2024 for (;;) { 2025 error = SWAP_PCTRIE_INSERT( 2026 &object->un_pager.swp.swp_blks, sb); 2027 if (error == 0) { 2028 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2029 1, 0)) 2030 printf("swpctrie zone ok\n"); 2031 break; 2032 } 2033 VM_OBJECT_WUNLOCK(object); 2034 if (uma_zone_exhausted(swpctrie_zone)) { 2035 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2036 0, 1)) 2037 printf("swap pctrie zone exhausted, " 2038 "increase kern.maxswzone\n"); 2039 vm_pageout_oom(VM_OOM_SWAPZ); 2040 pause("swzonxp", 10); 2041 } else 2042 uma_zwait(swpctrie_zone); 2043 VM_OBJECT_WLOCK(object); 2044 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2045 rdpi); 2046 if (sb1 != NULL) { 2047 uma_zfree(swblk_zone, sb); 2048 sb = sb1; 2049 goto allocated; 2050 } 2051 } 2052 } 2053 allocated: 2054 MPASS(sb->p == rdpi); 2055 2056 modpi = pindex % SWAP_META_PAGES; 2057 /* Return prior contents of metadata. */ 2058 prev_swapblk = sb->d[modpi]; 2059 /* Enter block into metadata. */ 2060 sb->d[modpi] = swapblk; 2061 2062 /* 2063 * Free the swblk if we end up with the empty page run. 2064 */ 2065 if (swapblk == SWAPBLK_NONE) 2066 swp_pager_free_empty_swblk(object, sb); 2067 return (prev_swapblk); 2068 } 2069 2070 /* 2071 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2072 * metadata, or transfer it into dstobject. 2073 * 2074 * This routine will free swap metadata structures as they are cleaned 2075 * out. 2076 */ 2077 static void 2078 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2079 vm_pindex_t pindex, vm_pindex_t count) 2080 { 2081 struct swblk *sb; 2082 daddr_t n_free, s_free; 2083 vm_pindex_t offset, last; 2084 int i, limit, start; 2085 2086 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2087 if (srcobject->type != OBJT_SWAP || count == 0) 2088 return; 2089 2090 swp_pager_init_freerange(&s_free, &n_free); 2091 offset = pindex; 2092 last = pindex + count; 2093 for (;;) { 2094 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2095 rounddown(pindex, SWAP_META_PAGES)); 2096 if (sb == NULL || sb->p >= last) 2097 break; 2098 start = pindex > sb->p ? pindex - sb->p : 0; 2099 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2100 SWAP_META_PAGES; 2101 for (i = start; i < limit; i++) { 2102 if (sb->d[i] == SWAPBLK_NONE) 2103 continue; 2104 if (dstobject == NULL || 2105 !swp_pager_xfer_source(srcobject, dstobject, 2106 sb->p + i - offset, sb->d[i])) { 2107 swp_pager_update_freerange(&s_free, &n_free, 2108 sb->d[i]); 2109 } 2110 sb->d[i] = SWAPBLK_NONE; 2111 } 2112 pindex = sb->p + SWAP_META_PAGES; 2113 if (swp_pager_swblk_empty(sb, 0, start) && 2114 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2115 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2116 sb->p); 2117 uma_zfree(swblk_zone, sb); 2118 } 2119 } 2120 swp_pager_freeswapspace(s_free, n_free); 2121 } 2122 2123 /* 2124 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2125 * 2126 * The requested range of blocks is freed, with any associated swap 2127 * returned to the swap bitmap. 2128 * 2129 * This routine will free swap metadata structures as they are cleaned 2130 * out. This routine does *NOT* operate on swap metadata associated 2131 * with resident pages. 2132 */ 2133 static void 2134 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2135 { 2136 swp_pager_meta_transfer(object, NULL, pindex, count); 2137 } 2138 2139 /* 2140 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2141 * 2142 * This routine locates and destroys all swap metadata associated with 2143 * an object. 2144 */ 2145 static void 2146 swp_pager_meta_free_all(vm_object_t object) 2147 { 2148 struct swblk *sb; 2149 daddr_t n_free, s_free; 2150 vm_pindex_t pindex; 2151 int i; 2152 2153 VM_OBJECT_ASSERT_WLOCKED(object); 2154 if (object->type != OBJT_SWAP) 2155 return; 2156 2157 swp_pager_init_freerange(&s_free, &n_free); 2158 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2159 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2160 pindex = sb->p + SWAP_META_PAGES; 2161 for (i = 0; i < SWAP_META_PAGES; i++) { 2162 if (sb->d[i] == SWAPBLK_NONE) 2163 continue; 2164 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2165 } 2166 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2167 uma_zfree(swblk_zone, sb); 2168 } 2169 swp_pager_freeswapspace(s_free, n_free); 2170 } 2171 2172 /* 2173 * SWP_PAGER_METACTL() - misc control of swap meta data. 2174 * 2175 * This routine is capable of looking up, or removing swapblk 2176 * assignments in the swap meta data. It returns the swapblk being 2177 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2178 * 2179 * When acting on a busy resident page and paging is in progress, we 2180 * have to wait until paging is complete but otherwise can act on the 2181 * busy page. 2182 */ 2183 static daddr_t 2184 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2185 { 2186 struct swblk *sb; 2187 2188 VM_OBJECT_ASSERT_LOCKED(object); 2189 2190 /* 2191 * The meta data only exists if the object is OBJT_SWAP 2192 * and even then might not be allocated yet. 2193 */ 2194 KASSERT(object->type == OBJT_SWAP, 2195 ("Lookup object not swappable")); 2196 2197 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2198 rounddown(pindex, SWAP_META_PAGES)); 2199 if (sb == NULL) 2200 return (SWAPBLK_NONE); 2201 return (sb->d[pindex % SWAP_META_PAGES]); 2202 } 2203 2204 /* 2205 * Returns the least page index which is greater than or equal to the 2206 * parameter pindex and for which there is a swap block allocated. 2207 * Returns object's size if the object's type is not swap or if there 2208 * are no allocated swap blocks for the object after the requested 2209 * pindex. 2210 */ 2211 vm_pindex_t 2212 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2213 { 2214 struct swblk *sb; 2215 int i; 2216 2217 VM_OBJECT_ASSERT_LOCKED(object); 2218 if (object->type != OBJT_SWAP) 2219 return (object->size); 2220 2221 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2222 rounddown(pindex, SWAP_META_PAGES)); 2223 if (sb == NULL) 2224 return (object->size); 2225 if (sb->p < pindex) { 2226 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2227 if (sb->d[i] != SWAPBLK_NONE) 2228 return (sb->p + i); 2229 } 2230 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2231 roundup(pindex, SWAP_META_PAGES)); 2232 if (sb == NULL) 2233 return (object->size); 2234 } 2235 for (i = 0; i < SWAP_META_PAGES; i++) { 2236 if (sb->d[i] != SWAPBLK_NONE) 2237 return (sb->p + i); 2238 } 2239 2240 /* 2241 * We get here if a swblk is present in the trie but it 2242 * doesn't map any blocks. 2243 */ 2244 MPASS(0); 2245 return (object->size); 2246 } 2247 2248 /* 2249 * System call swapon(name) enables swapping on device name, 2250 * which must be in the swdevsw. Return EBUSY 2251 * if already swapping on this device. 2252 */ 2253 #ifndef _SYS_SYSPROTO_H_ 2254 struct swapon_args { 2255 char *name; 2256 }; 2257 #endif 2258 2259 /* 2260 * MPSAFE 2261 */ 2262 /* ARGSUSED */ 2263 int 2264 sys_swapon(struct thread *td, struct swapon_args *uap) 2265 { 2266 struct vattr attr; 2267 struct vnode *vp; 2268 struct nameidata nd; 2269 int error; 2270 2271 error = priv_check(td, PRIV_SWAPON); 2272 if (error) 2273 return (error); 2274 2275 sx_xlock(&swdev_syscall_lock); 2276 2277 /* 2278 * Swap metadata may not fit in the KVM if we have physical 2279 * memory of >1GB. 2280 */ 2281 if (swblk_zone == NULL) { 2282 error = ENOMEM; 2283 goto done; 2284 } 2285 2286 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2287 uap->name, td); 2288 error = namei(&nd); 2289 if (error) 2290 goto done; 2291 2292 NDFREE(&nd, NDF_ONLY_PNBUF); 2293 vp = nd.ni_vp; 2294 2295 if (vn_isdisk(vp, &error)) { 2296 error = swapongeom(vp); 2297 } else if (vp->v_type == VREG && 2298 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2299 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2300 /* 2301 * Allow direct swapping to NFS regular files in the same 2302 * way that nfs_mountroot() sets up diskless swapping. 2303 */ 2304 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2305 } 2306 2307 if (error) 2308 vrele(vp); 2309 done: 2310 sx_xunlock(&swdev_syscall_lock); 2311 return (error); 2312 } 2313 2314 /* 2315 * Check that the total amount of swap currently configured does not 2316 * exceed half the theoretical maximum. If it does, print a warning 2317 * message. 2318 */ 2319 static void 2320 swapon_check_swzone(void) 2321 { 2322 2323 /* recommend using no more than half that amount */ 2324 if (swap_total > swap_maxpages / 2) { 2325 printf("warning: total configured swap (%lu pages) " 2326 "exceeds maximum recommended amount (%lu pages).\n", 2327 swap_total, swap_maxpages / 2); 2328 printf("warning: increase kern.maxswzone " 2329 "or reduce amount of swap.\n"); 2330 } 2331 } 2332 2333 static void 2334 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2335 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2336 { 2337 struct swdevt *sp, *tsp; 2338 daddr_t dvbase; 2339 u_long mblocks; 2340 2341 /* 2342 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2343 * First chop nblks off to page-align it, then convert. 2344 * 2345 * sw->sw_nblks is in page-sized chunks now too. 2346 */ 2347 nblks &= ~(ctodb(1) - 1); 2348 nblks = dbtoc(nblks); 2349 2350 /* 2351 * If we go beyond this, we get overflows in the radix 2352 * tree bitmap code. 2353 */ 2354 mblocks = 0x40000000 / BLIST_META_RADIX; 2355 if (nblks > mblocks) { 2356 printf( 2357 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2358 mblocks / 1024 / 1024 * PAGE_SIZE); 2359 nblks = mblocks; 2360 } 2361 2362 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2363 sp->sw_vp = vp; 2364 sp->sw_id = id; 2365 sp->sw_dev = dev; 2366 sp->sw_nblks = nblks; 2367 sp->sw_used = 0; 2368 sp->sw_strategy = strategy; 2369 sp->sw_close = close; 2370 sp->sw_flags = flags; 2371 2372 sp->sw_blist = blist_create(nblks, M_WAITOK); 2373 /* 2374 * Do not free the first blocks in order to avoid overwriting 2375 * any bsd label at the front of the partition 2376 */ 2377 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2378 nblks - howmany(BBSIZE, PAGE_SIZE)); 2379 2380 dvbase = 0; 2381 mtx_lock(&sw_dev_mtx); 2382 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2383 if (tsp->sw_end >= dvbase) { 2384 /* 2385 * We put one uncovered page between the devices 2386 * in order to definitively prevent any cross-device 2387 * I/O requests 2388 */ 2389 dvbase = tsp->sw_end + 1; 2390 } 2391 } 2392 sp->sw_first = dvbase; 2393 sp->sw_end = dvbase + nblks; 2394 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2395 nswapdev++; 2396 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2397 swap_total += nblks; 2398 swapon_check_swzone(); 2399 swp_sizecheck(); 2400 mtx_unlock(&sw_dev_mtx); 2401 EVENTHANDLER_INVOKE(swapon, sp); 2402 } 2403 2404 /* 2405 * SYSCALL: swapoff(devname) 2406 * 2407 * Disable swapping on the given device. 2408 * 2409 * XXX: Badly designed system call: it should use a device index 2410 * rather than filename as specification. We keep sw_vp around 2411 * only to make this work. 2412 */ 2413 #ifndef _SYS_SYSPROTO_H_ 2414 struct swapoff_args { 2415 char *name; 2416 }; 2417 #endif 2418 2419 /* 2420 * MPSAFE 2421 */ 2422 /* ARGSUSED */ 2423 int 2424 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2425 { 2426 struct vnode *vp; 2427 struct nameidata nd; 2428 struct swdevt *sp; 2429 int error; 2430 2431 error = priv_check(td, PRIV_SWAPOFF); 2432 if (error) 2433 return (error); 2434 2435 sx_xlock(&swdev_syscall_lock); 2436 2437 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2438 td); 2439 error = namei(&nd); 2440 if (error) 2441 goto done; 2442 NDFREE(&nd, NDF_ONLY_PNBUF); 2443 vp = nd.ni_vp; 2444 2445 mtx_lock(&sw_dev_mtx); 2446 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2447 if (sp->sw_vp == vp) 2448 break; 2449 } 2450 mtx_unlock(&sw_dev_mtx); 2451 if (sp == NULL) { 2452 error = EINVAL; 2453 goto done; 2454 } 2455 error = swapoff_one(sp, td->td_ucred); 2456 done: 2457 sx_xunlock(&swdev_syscall_lock); 2458 return (error); 2459 } 2460 2461 static int 2462 swapoff_one(struct swdevt *sp, struct ucred *cred) 2463 { 2464 u_long nblks; 2465 #ifdef MAC 2466 int error; 2467 #endif 2468 2469 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2470 #ifdef MAC 2471 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2472 error = mac_system_check_swapoff(cred, sp->sw_vp); 2473 (void) VOP_UNLOCK(sp->sw_vp); 2474 if (error != 0) 2475 return (error); 2476 #endif 2477 nblks = sp->sw_nblks; 2478 2479 /* 2480 * We can turn off this swap device safely only if the 2481 * available virtual memory in the system will fit the amount 2482 * of data we will have to page back in, plus an epsilon so 2483 * the system doesn't become critically low on swap space. 2484 */ 2485 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2486 return (ENOMEM); 2487 2488 /* 2489 * Prevent further allocations on this device. 2490 */ 2491 mtx_lock(&sw_dev_mtx); 2492 sp->sw_flags |= SW_CLOSING; 2493 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2494 swap_total -= nblks; 2495 mtx_unlock(&sw_dev_mtx); 2496 2497 /* 2498 * Page in the contents of the device and close it. 2499 */ 2500 swap_pager_swapoff(sp); 2501 2502 sp->sw_close(curthread, sp); 2503 mtx_lock(&sw_dev_mtx); 2504 sp->sw_id = NULL; 2505 TAILQ_REMOVE(&swtailq, sp, sw_list); 2506 nswapdev--; 2507 if (nswapdev == 0) { 2508 swap_pager_full = 2; 2509 swap_pager_almost_full = 1; 2510 } 2511 if (swdevhd == sp) 2512 swdevhd = NULL; 2513 mtx_unlock(&sw_dev_mtx); 2514 blist_destroy(sp->sw_blist); 2515 free(sp, M_VMPGDATA); 2516 return (0); 2517 } 2518 2519 void 2520 swapoff_all(void) 2521 { 2522 struct swdevt *sp, *spt; 2523 const char *devname; 2524 int error; 2525 2526 sx_xlock(&swdev_syscall_lock); 2527 2528 mtx_lock(&sw_dev_mtx); 2529 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2530 mtx_unlock(&sw_dev_mtx); 2531 if (vn_isdisk(sp->sw_vp, NULL)) 2532 devname = devtoname(sp->sw_vp->v_rdev); 2533 else 2534 devname = "[file]"; 2535 error = swapoff_one(sp, thread0.td_ucred); 2536 if (error != 0) { 2537 printf("Cannot remove swap device %s (error=%d), " 2538 "skipping.\n", devname, error); 2539 } else if (bootverbose) { 2540 printf("Swap device %s removed.\n", devname); 2541 } 2542 mtx_lock(&sw_dev_mtx); 2543 } 2544 mtx_unlock(&sw_dev_mtx); 2545 2546 sx_xunlock(&swdev_syscall_lock); 2547 } 2548 2549 void 2550 swap_pager_status(int *total, int *used) 2551 { 2552 struct swdevt *sp; 2553 2554 *total = 0; 2555 *used = 0; 2556 mtx_lock(&sw_dev_mtx); 2557 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2558 *total += sp->sw_nblks; 2559 *used += sp->sw_used; 2560 } 2561 mtx_unlock(&sw_dev_mtx); 2562 } 2563 2564 int 2565 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2566 { 2567 struct swdevt *sp; 2568 const char *tmp_devname; 2569 int error, n; 2570 2571 n = 0; 2572 error = ENOENT; 2573 mtx_lock(&sw_dev_mtx); 2574 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2575 if (n != name) { 2576 n++; 2577 continue; 2578 } 2579 xs->xsw_version = XSWDEV_VERSION; 2580 xs->xsw_dev = sp->sw_dev; 2581 xs->xsw_flags = sp->sw_flags; 2582 xs->xsw_nblks = sp->sw_nblks; 2583 xs->xsw_used = sp->sw_used; 2584 if (devname != NULL) { 2585 if (vn_isdisk(sp->sw_vp, NULL)) 2586 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2587 else 2588 tmp_devname = "[file]"; 2589 strncpy(devname, tmp_devname, len); 2590 } 2591 error = 0; 2592 break; 2593 } 2594 mtx_unlock(&sw_dev_mtx); 2595 return (error); 2596 } 2597 2598 #if defined(COMPAT_FREEBSD11) 2599 #define XSWDEV_VERSION_11 1 2600 struct xswdev11 { 2601 u_int xsw_version; 2602 uint32_t xsw_dev; 2603 int xsw_flags; 2604 int xsw_nblks; 2605 int xsw_used; 2606 }; 2607 #endif 2608 2609 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2610 struct xswdev32 { 2611 u_int xsw_version; 2612 u_int xsw_dev1, xsw_dev2; 2613 int xsw_flags; 2614 int xsw_nblks; 2615 int xsw_used; 2616 }; 2617 #endif 2618 2619 static int 2620 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2621 { 2622 struct xswdev xs; 2623 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2624 struct xswdev32 xs32; 2625 #endif 2626 #if defined(COMPAT_FREEBSD11) 2627 struct xswdev11 xs11; 2628 #endif 2629 int error; 2630 2631 if (arg2 != 1) /* name length */ 2632 return (EINVAL); 2633 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2634 if (error != 0) 2635 return (error); 2636 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2637 if (req->oldlen == sizeof(xs32)) { 2638 xs32.xsw_version = XSWDEV_VERSION; 2639 xs32.xsw_dev1 = xs.xsw_dev; 2640 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2641 xs32.xsw_flags = xs.xsw_flags; 2642 xs32.xsw_nblks = xs.xsw_nblks; 2643 xs32.xsw_used = xs.xsw_used; 2644 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2645 return (error); 2646 } 2647 #endif 2648 #if defined(COMPAT_FREEBSD11) 2649 if (req->oldlen == sizeof(xs11)) { 2650 xs11.xsw_version = XSWDEV_VERSION_11; 2651 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2652 xs11.xsw_flags = xs.xsw_flags; 2653 xs11.xsw_nblks = xs.xsw_nblks; 2654 xs11.xsw_used = xs.xsw_used; 2655 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2656 return (error); 2657 } 2658 #endif 2659 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2660 return (error); 2661 } 2662 2663 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2664 "Number of swap devices"); 2665 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2666 sysctl_vm_swap_info, 2667 "Swap statistics by device"); 2668 2669 /* 2670 * Count the approximate swap usage in pages for a vmspace. The 2671 * shadowed or not yet copied on write swap blocks are not accounted. 2672 * The map must be locked. 2673 */ 2674 long 2675 vmspace_swap_count(struct vmspace *vmspace) 2676 { 2677 vm_map_t map; 2678 vm_map_entry_t cur; 2679 vm_object_t object; 2680 struct swblk *sb; 2681 vm_pindex_t e, pi; 2682 long count; 2683 int i; 2684 2685 map = &vmspace->vm_map; 2686 count = 0; 2687 2688 VM_MAP_ENTRY_FOREACH(cur, map) { 2689 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2690 continue; 2691 object = cur->object.vm_object; 2692 if (object == NULL || object->type != OBJT_SWAP) 2693 continue; 2694 VM_OBJECT_RLOCK(object); 2695 if (object->type != OBJT_SWAP) 2696 goto unlock; 2697 pi = OFF_TO_IDX(cur->offset); 2698 e = pi + OFF_TO_IDX(cur->end - cur->start); 2699 for (;; pi = sb->p + SWAP_META_PAGES) { 2700 sb = SWAP_PCTRIE_LOOKUP_GE( 2701 &object->un_pager.swp.swp_blks, pi); 2702 if (sb == NULL || sb->p >= e) 2703 break; 2704 for (i = 0; i < SWAP_META_PAGES; i++) { 2705 if (sb->p + i < e && 2706 sb->d[i] != SWAPBLK_NONE) 2707 count++; 2708 } 2709 } 2710 unlock: 2711 VM_OBJECT_RUNLOCK(object); 2712 } 2713 return (count); 2714 } 2715 2716 /* 2717 * GEOM backend 2718 * 2719 * Swapping onto disk devices. 2720 * 2721 */ 2722 2723 static g_orphan_t swapgeom_orphan; 2724 2725 static struct g_class g_swap_class = { 2726 .name = "SWAP", 2727 .version = G_VERSION, 2728 .orphan = swapgeom_orphan, 2729 }; 2730 2731 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2732 2733 2734 static void 2735 swapgeom_close_ev(void *arg, int flags) 2736 { 2737 struct g_consumer *cp; 2738 2739 cp = arg; 2740 g_access(cp, -1, -1, 0); 2741 g_detach(cp); 2742 g_destroy_consumer(cp); 2743 } 2744 2745 /* 2746 * Add a reference to the g_consumer for an inflight transaction. 2747 */ 2748 static void 2749 swapgeom_acquire(struct g_consumer *cp) 2750 { 2751 2752 mtx_assert(&sw_dev_mtx, MA_OWNED); 2753 cp->index++; 2754 } 2755 2756 /* 2757 * Remove a reference from the g_consumer. Post a close event if all 2758 * references go away, since the function might be called from the 2759 * biodone context. 2760 */ 2761 static void 2762 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2763 { 2764 2765 mtx_assert(&sw_dev_mtx, MA_OWNED); 2766 cp->index--; 2767 if (cp->index == 0) { 2768 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2769 sp->sw_id = NULL; 2770 } 2771 } 2772 2773 static void 2774 swapgeom_done(struct bio *bp2) 2775 { 2776 struct swdevt *sp; 2777 struct buf *bp; 2778 struct g_consumer *cp; 2779 2780 bp = bp2->bio_caller2; 2781 cp = bp2->bio_from; 2782 bp->b_ioflags = bp2->bio_flags; 2783 if (bp2->bio_error) 2784 bp->b_ioflags |= BIO_ERROR; 2785 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2786 bp->b_error = bp2->bio_error; 2787 bp->b_caller1 = NULL; 2788 bufdone(bp); 2789 sp = bp2->bio_caller1; 2790 mtx_lock(&sw_dev_mtx); 2791 swapgeom_release(cp, sp); 2792 mtx_unlock(&sw_dev_mtx); 2793 g_destroy_bio(bp2); 2794 } 2795 2796 static void 2797 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2798 { 2799 struct bio *bio; 2800 struct g_consumer *cp; 2801 2802 mtx_lock(&sw_dev_mtx); 2803 cp = sp->sw_id; 2804 if (cp == NULL) { 2805 mtx_unlock(&sw_dev_mtx); 2806 bp->b_error = ENXIO; 2807 bp->b_ioflags |= BIO_ERROR; 2808 bufdone(bp); 2809 return; 2810 } 2811 swapgeom_acquire(cp); 2812 mtx_unlock(&sw_dev_mtx); 2813 if (bp->b_iocmd == BIO_WRITE) 2814 bio = g_new_bio(); 2815 else 2816 bio = g_alloc_bio(); 2817 if (bio == NULL) { 2818 mtx_lock(&sw_dev_mtx); 2819 swapgeom_release(cp, sp); 2820 mtx_unlock(&sw_dev_mtx); 2821 bp->b_error = ENOMEM; 2822 bp->b_ioflags |= BIO_ERROR; 2823 printf("swap_pager: cannot allocate bio\n"); 2824 bufdone(bp); 2825 return; 2826 } 2827 2828 bp->b_caller1 = bio; 2829 bio->bio_caller1 = sp; 2830 bio->bio_caller2 = bp; 2831 bio->bio_cmd = bp->b_iocmd; 2832 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2833 bio->bio_length = bp->b_bcount; 2834 bio->bio_done = swapgeom_done; 2835 if (!buf_mapped(bp)) { 2836 bio->bio_ma = bp->b_pages; 2837 bio->bio_data = unmapped_buf; 2838 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2839 bio->bio_ma_n = bp->b_npages; 2840 bio->bio_flags |= BIO_UNMAPPED; 2841 } else { 2842 bio->bio_data = bp->b_data; 2843 bio->bio_ma = NULL; 2844 } 2845 g_io_request(bio, cp); 2846 return; 2847 } 2848 2849 static void 2850 swapgeom_orphan(struct g_consumer *cp) 2851 { 2852 struct swdevt *sp; 2853 int destroy; 2854 2855 mtx_lock(&sw_dev_mtx); 2856 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2857 if (sp->sw_id == cp) { 2858 sp->sw_flags |= SW_CLOSING; 2859 break; 2860 } 2861 } 2862 /* 2863 * Drop reference we were created with. Do directly since we're in a 2864 * special context where we don't have to queue the call to 2865 * swapgeom_close_ev(). 2866 */ 2867 cp->index--; 2868 destroy = ((sp != NULL) && (cp->index == 0)); 2869 if (destroy) 2870 sp->sw_id = NULL; 2871 mtx_unlock(&sw_dev_mtx); 2872 if (destroy) 2873 swapgeom_close_ev(cp, 0); 2874 } 2875 2876 static void 2877 swapgeom_close(struct thread *td, struct swdevt *sw) 2878 { 2879 struct g_consumer *cp; 2880 2881 mtx_lock(&sw_dev_mtx); 2882 cp = sw->sw_id; 2883 sw->sw_id = NULL; 2884 mtx_unlock(&sw_dev_mtx); 2885 2886 /* 2887 * swapgeom_close() may be called from the biodone context, 2888 * where we cannot perform topology changes. Delegate the 2889 * work to the events thread. 2890 */ 2891 if (cp != NULL) 2892 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2893 } 2894 2895 static int 2896 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2897 { 2898 struct g_provider *pp; 2899 struct g_consumer *cp; 2900 static struct g_geom *gp; 2901 struct swdevt *sp; 2902 u_long nblks; 2903 int error; 2904 2905 pp = g_dev_getprovider(dev); 2906 if (pp == NULL) 2907 return (ENODEV); 2908 mtx_lock(&sw_dev_mtx); 2909 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2910 cp = sp->sw_id; 2911 if (cp != NULL && cp->provider == pp) { 2912 mtx_unlock(&sw_dev_mtx); 2913 return (EBUSY); 2914 } 2915 } 2916 mtx_unlock(&sw_dev_mtx); 2917 if (gp == NULL) 2918 gp = g_new_geomf(&g_swap_class, "swap"); 2919 cp = g_new_consumer(gp); 2920 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2921 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2922 g_attach(cp, pp); 2923 /* 2924 * XXX: Every time you think you can improve the margin for 2925 * footshooting, somebody depends on the ability to do so: 2926 * savecore(8) wants to write to our swapdev so we cannot 2927 * set an exclusive count :-( 2928 */ 2929 error = g_access(cp, 1, 1, 0); 2930 if (error != 0) { 2931 g_detach(cp); 2932 g_destroy_consumer(cp); 2933 return (error); 2934 } 2935 nblks = pp->mediasize / DEV_BSIZE; 2936 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2937 swapgeom_close, dev2udev(dev), 2938 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2939 return (0); 2940 } 2941 2942 static int 2943 swapongeom(struct vnode *vp) 2944 { 2945 int error; 2946 2947 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2948 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 2949 error = ENOENT; 2950 } else { 2951 g_topology_lock(); 2952 error = swapongeom_locked(vp->v_rdev, vp); 2953 g_topology_unlock(); 2954 } 2955 VOP_UNLOCK(vp); 2956 return (error); 2957 } 2958 2959 /* 2960 * VNODE backend 2961 * 2962 * This is used mainly for network filesystem (read: probably only tested 2963 * with NFS) swapfiles. 2964 * 2965 */ 2966 2967 static void 2968 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2969 { 2970 struct vnode *vp2; 2971 2972 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2973 2974 vp2 = sp->sw_id; 2975 vhold(vp2); 2976 if (bp->b_iocmd == BIO_WRITE) { 2977 if (bp->b_bufobj) 2978 bufobj_wdrop(bp->b_bufobj); 2979 bufobj_wref(&vp2->v_bufobj); 2980 } 2981 if (bp->b_bufobj != &vp2->v_bufobj) 2982 bp->b_bufobj = &vp2->v_bufobj; 2983 bp->b_vp = vp2; 2984 bp->b_iooffset = dbtob(bp->b_blkno); 2985 bstrategy(bp); 2986 return; 2987 } 2988 2989 static void 2990 swapdev_close(struct thread *td, struct swdevt *sp) 2991 { 2992 2993 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2994 vrele(sp->sw_vp); 2995 } 2996 2997 2998 static int 2999 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3000 { 3001 struct swdevt *sp; 3002 int error; 3003 3004 if (nblks == 0) 3005 return (ENXIO); 3006 mtx_lock(&sw_dev_mtx); 3007 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3008 if (sp->sw_id == vp) { 3009 mtx_unlock(&sw_dev_mtx); 3010 return (EBUSY); 3011 } 3012 } 3013 mtx_unlock(&sw_dev_mtx); 3014 3015 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3016 #ifdef MAC 3017 error = mac_system_check_swapon(td->td_ucred, vp); 3018 if (error == 0) 3019 #endif 3020 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3021 (void) VOP_UNLOCK(vp); 3022 if (error) 3023 return (error); 3024 3025 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3026 NODEV, 0); 3027 return (0); 3028 } 3029 3030 static int 3031 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3032 { 3033 int error, new, n; 3034 3035 new = nsw_wcount_async_max; 3036 error = sysctl_handle_int(oidp, &new, 0, req); 3037 if (error != 0 || req->newptr == NULL) 3038 return (error); 3039 3040 if (new > nswbuf / 2 || new < 1) 3041 return (EINVAL); 3042 3043 mtx_lock(&swbuf_mtx); 3044 while (nsw_wcount_async_max != new) { 3045 /* 3046 * Adjust difference. If the current async count is too low, 3047 * we will need to sqeeze our update slowly in. Sleep with a 3048 * higher priority than getpbuf() to finish faster. 3049 */ 3050 n = new - nsw_wcount_async_max; 3051 if (nsw_wcount_async + n >= 0) { 3052 nsw_wcount_async += n; 3053 nsw_wcount_async_max += n; 3054 wakeup(&nsw_wcount_async); 3055 } else { 3056 nsw_wcount_async_max -= nsw_wcount_async; 3057 nsw_wcount_async = 0; 3058 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3059 "swpsysctl", 0); 3060 } 3061 } 3062 mtx_unlock(&swbuf_mtx); 3063 3064 return (0); 3065 } 3066 3067 static void 3068 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3069 vm_offset_t end) 3070 { 3071 3072 VM_OBJECT_WLOCK(object); 3073 KASSERT((object->flags & OBJ_ANON) == 0, 3074 ("Splittable object with writecount")); 3075 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3076 VM_OBJECT_WUNLOCK(object); 3077 } 3078 3079 static void 3080 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3081 vm_offset_t end) 3082 { 3083 3084 VM_OBJECT_WLOCK(object); 3085 KASSERT((object->flags & OBJ_ANON) == 0, 3086 ("Splittable object with writecount")); 3087 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3088 VM_OBJECT_WUNLOCK(object); 3089 } 3090