1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/bio.h> 78 #include <sys/blist.h> 79 #include <sys/buf.h> 80 #include <sys/conf.h> 81 #include <sys/disk.h> 82 #include <sys/disklabel.h> 83 #include <sys/eventhandler.h> 84 #include <sys/fcntl.h> 85 #include <sys/lock.h> 86 #include <sys/kernel.h> 87 #include <sys/mount.h> 88 #include <sys/namei.h> 89 #include <sys/malloc.h> 90 #include <sys/pctrie.h> 91 #include <sys/priv.h> 92 #include <sys/proc.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/systm.h> 101 #include <sys/sx.h> 102 #include <sys/vmmeter.h> 103 #include <sys/vnode.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static u_long swap_reserved; 156 static u_long swap_total; 157 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 158 159 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 160 "VM swap stats"); 161 162 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 163 &swap_reserved, 0, sysctl_page_shift, "A", 164 "Amount of swap storage needed to back all allocated anonymous memory."); 165 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 166 &swap_total, 0, sysctl_page_shift, "A", 167 "Total amount of available swap storage."); 168 169 static int overcommit = 0; 170 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 171 "Configure virtual memory overcommit behavior. See tuning(7) " 172 "for details."); 173 static unsigned long swzone; 174 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 175 "Actual size of swap metadata zone"); 176 static unsigned long swap_maxpages; 177 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 178 "Maximum amount of swap supported"); 179 180 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); 181 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 182 CTLFLAG_RD, &swap_free_deferred, 183 "Number of pages that deferred freeing swap space"); 184 185 static COUNTER_U64_DEFINE_EARLY(swap_free_completed); 186 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 187 CTLFLAG_RD, &swap_free_completed, 188 "Number of deferred frees completed"); 189 190 /* bits from overcommit */ 191 #define SWAP_RESERVE_FORCE_ON (1 << 0) 192 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 193 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 194 195 static int 196 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 197 { 198 uint64_t newval; 199 u_long value = *(u_long *)arg1; 200 201 newval = ((uint64_t)value) << PAGE_SHIFT; 202 return (sysctl_handle_64(oidp, &newval, 0, req)); 203 } 204 205 int 206 swap_reserve(vm_ooffset_t incr) 207 { 208 209 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 210 } 211 212 int 213 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 214 { 215 u_long r, s, prev, pincr; 216 int res, error; 217 static int curfail; 218 static struct timeval lastfail; 219 struct uidinfo *uip; 220 221 uip = cred->cr_ruidinfo; 222 223 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 224 (uintmax_t)incr)); 225 226 #ifdef RACCT 227 if (racct_enable) { 228 PROC_LOCK(curproc); 229 error = racct_add(curproc, RACCT_SWAP, incr); 230 PROC_UNLOCK(curproc); 231 if (error != 0) 232 return (0); 233 } 234 #endif 235 236 pincr = atop(incr); 237 res = 0; 238 prev = atomic_fetchadd_long(&swap_reserved, pincr); 239 r = prev + pincr; 240 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 241 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 242 vm_wire_count(); 243 } else 244 s = 0; 245 s += swap_total; 246 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 247 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 248 res = 1; 249 } else { 250 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 251 if (prev < pincr) 252 panic("swap_reserved < incr on overcommit fail"); 253 } 254 if (res) { 255 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 256 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 257 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 258 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 259 res = 0; 260 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 261 if (prev < pincr) 262 panic("uip->ui_vmsize < incr on overcommit fail"); 263 } 264 } 265 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 266 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 267 uip->ui_uid, curproc->p_pid, incr); 268 } 269 270 #ifdef RACCT 271 if (racct_enable && !res) { 272 PROC_LOCK(curproc); 273 racct_sub(curproc, RACCT_SWAP, incr); 274 PROC_UNLOCK(curproc); 275 } 276 #endif 277 278 return (res); 279 } 280 281 void 282 swap_reserve_force(vm_ooffset_t incr) 283 { 284 struct uidinfo *uip; 285 u_long pincr; 286 287 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 288 (uintmax_t)incr)); 289 290 PROC_LOCK(curproc); 291 #ifdef RACCT 292 if (racct_enable) 293 racct_add_force(curproc, RACCT_SWAP, incr); 294 #endif 295 pincr = atop(incr); 296 atomic_add_long(&swap_reserved, pincr); 297 uip = curproc->p_ucred->cr_ruidinfo; 298 atomic_add_long(&uip->ui_vmsize, pincr); 299 PROC_UNLOCK(curproc); 300 } 301 302 void 303 swap_release(vm_ooffset_t decr) 304 { 305 struct ucred *cred; 306 307 PROC_LOCK(curproc); 308 cred = curproc->p_ucred; 309 swap_release_by_cred(decr, cred); 310 PROC_UNLOCK(curproc); 311 } 312 313 void 314 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 315 { 316 u_long prev, pdecr; 317 struct uidinfo *uip; 318 319 uip = cred->cr_ruidinfo; 320 321 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 322 (uintmax_t)decr)); 323 324 pdecr = atop(decr); 325 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 326 if (prev < pdecr) 327 panic("swap_reserved < decr"); 328 329 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 330 if (prev < pdecr) 331 printf("negative vmsize for uid = %d\n", uip->ui_uid); 332 #ifdef RACCT 333 if (racct_enable) 334 racct_sub_cred(cred, RACCT_SWAP, decr); 335 #endif 336 } 337 338 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 339 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 340 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 341 static int nsw_wcount_async; /* limit async write buffers */ 342 static int nsw_wcount_async_max;/* assigned maximum */ 343 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 344 345 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 346 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 347 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 348 "Maximum running async swap ops"); 349 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 350 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 351 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 352 "Swap Fragmentation Info"); 353 354 static struct sx sw_alloc_sx; 355 356 /* 357 * "named" and "unnamed" anon region objects. Try to reduce the overhead 358 * of searching a named list by hashing it just a little. 359 */ 360 361 #define NOBJLISTS 8 362 363 #define NOBJLIST(handle) \ 364 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 365 366 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 367 static uma_zone_t swwbuf_zone; 368 static uma_zone_t swrbuf_zone; 369 static uma_zone_t swblk_zone; 370 static uma_zone_t swpctrie_zone; 371 372 /* 373 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 374 * calls hooked from other parts of the VM system and do not appear here. 375 * (see vm/swap_pager.h). 376 */ 377 static vm_object_t 378 swap_pager_alloc(void *handle, vm_ooffset_t size, 379 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 380 static void swap_pager_dealloc(vm_object_t object); 381 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 382 int *); 383 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 384 int *, pgo_getpages_iodone_t, void *); 385 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 386 static boolean_t 387 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 388 static void swap_pager_init(void); 389 static void swap_pager_unswapped(vm_page_t); 390 static void swap_pager_swapoff(struct swdevt *sp); 391 static void swap_pager_update_writecount(vm_object_t object, 392 vm_offset_t start, vm_offset_t end); 393 static void swap_pager_release_writecount(vm_object_t object, 394 vm_offset_t start, vm_offset_t end); 395 396 struct pagerops swappagerops = { 397 .pgo_init = swap_pager_init, /* early system initialization of pager */ 398 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 399 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 400 .pgo_getpages = swap_pager_getpages, /* pagein */ 401 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 402 .pgo_putpages = swap_pager_putpages, /* pageout */ 403 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 404 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 405 .pgo_update_writecount = swap_pager_update_writecount, 406 .pgo_release_writecount = swap_pager_release_writecount, 407 }; 408 409 /* 410 * swap_*() routines are externally accessible. swp_*() routines are 411 * internal. 412 */ 413 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 414 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 415 416 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 417 "Maximum size of a swap block in pages"); 418 419 static void swp_sizecheck(void); 420 static void swp_pager_async_iodone(struct buf *bp); 421 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 422 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 423 static int swapongeom(struct vnode *); 424 static int swaponvp(struct thread *, struct vnode *, u_long); 425 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 426 427 /* 428 * Swap bitmap functions 429 */ 430 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 431 static daddr_t swp_pager_getswapspace(int *npages); 432 433 /* 434 * Metadata functions 435 */ 436 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 437 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 438 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 439 vm_pindex_t pindex, vm_pindex_t count); 440 static void swp_pager_meta_free_all(vm_object_t); 441 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 442 443 static void 444 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 445 { 446 447 *start = SWAPBLK_NONE; 448 *num = 0; 449 } 450 451 static void 452 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 453 { 454 455 if (*start + *num == addr) { 456 (*num)++; 457 } else { 458 swp_pager_freeswapspace(*start, *num); 459 *start = addr; 460 *num = 1; 461 } 462 } 463 464 static void * 465 swblk_trie_alloc(struct pctrie *ptree) 466 { 467 468 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 469 M_USE_RESERVE : 0))); 470 } 471 472 static void 473 swblk_trie_free(struct pctrie *ptree, void *node) 474 { 475 476 uma_zfree(swpctrie_zone, node); 477 } 478 479 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 480 481 /* 482 * SWP_SIZECHECK() - update swap_pager_full indication 483 * 484 * update the swap_pager_almost_full indication and warn when we are 485 * about to run out of swap space, using lowat/hiwat hysteresis. 486 * 487 * Clear swap_pager_full ( task killing ) indication when lowat is met. 488 * 489 * No restrictions on call 490 * This routine may not block. 491 */ 492 static void 493 swp_sizecheck(void) 494 { 495 496 if (swap_pager_avail < nswap_lowat) { 497 if (swap_pager_almost_full == 0) { 498 printf("swap_pager: out of swap space\n"); 499 swap_pager_almost_full = 1; 500 } 501 } else { 502 swap_pager_full = 0; 503 if (swap_pager_avail > nswap_hiwat) 504 swap_pager_almost_full = 0; 505 } 506 } 507 508 /* 509 * SWAP_PAGER_INIT() - initialize the swap pager! 510 * 511 * Expected to be started from system init. NOTE: This code is run 512 * before much else so be careful what you depend on. Most of the VM 513 * system has yet to be initialized at this point. 514 */ 515 static void 516 swap_pager_init(void) 517 { 518 /* 519 * Initialize object lists 520 */ 521 int i; 522 523 for (i = 0; i < NOBJLISTS; ++i) 524 TAILQ_INIT(&swap_pager_object_list[i]); 525 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 526 sx_init(&sw_alloc_sx, "swspsx"); 527 sx_init(&swdev_syscall_lock, "swsysc"); 528 } 529 530 /* 531 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 532 * 533 * Expected to be started from pageout process once, prior to entering 534 * its main loop. 535 */ 536 void 537 swap_pager_swap_init(void) 538 { 539 unsigned long n, n2; 540 541 /* 542 * Number of in-transit swap bp operations. Don't 543 * exhaust the pbufs completely. Make sure we 544 * initialize workable values (0 will work for hysteresis 545 * but it isn't very efficient). 546 * 547 * The nsw_cluster_max is constrained by the bp->b_pages[] 548 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 549 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 550 * constrained by the swap device interleave stripe size. 551 * 552 * Currently we hardwire nsw_wcount_async to 4. This limit is 553 * designed to prevent other I/O from having high latencies due to 554 * our pageout I/O. The value 4 works well for one or two active swap 555 * devices but is probably a little low if you have more. Even so, 556 * a higher value would probably generate only a limited improvement 557 * with three or four active swap devices since the system does not 558 * typically have to pageout at extreme bandwidths. We will want 559 * at least 2 per swap devices, and 4 is a pretty good value if you 560 * have one NFS swap device due to the command/ack latency over NFS. 561 * So it all works out pretty well. 562 */ 563 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 564 565 nsw_wcount_async = 4; 566 nsw_wcount_async_max = nsw_wcount_async; 567 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 568 569 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 570 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 571 572 /* 573 * Initialize our zone, taking the user's requested size or 574 * estimating the number we need based on the number of pages 575 * in the system. 576 */ 577 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 578 vm_cnt.v_page_count / 2; 579 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 580 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 581 if (swpctrie_zone == NULL) 582 panic("failed to create swap pctrie zone."); 583 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 584 NULL, NULL, _Alignof(struct swblk) - 1, 0); 585 if (swblk_zone == NULL) 586 panic("failed to create swap blk zone."); 587 n2 = n; 588 do { 589 if (uma_zone_reserve_kva(swblk_zone, n)) 590 break; 591 /* 592 * if the allocation failed, try a zone two thirds the 593 * size of the previous attempt. 594 */ 595 n -= ((n + 2) / 3); 596 } while (n > 0); 597 598 /* 599 * Often uma_zone_reserve_kva() cannot reserve exactly the 600 * requested size. Account for the difference when 601 * calculating swap_maxpages. 602 */ 603 n = uma_zone_get_max(swblk_zone); 604 605 if (n < n2) 606 printf("Swap blk zone entries changed from %lu to %lu.\n", 607 n2, n); 608 /* absolute maximum we can handle assuming 100% efficiency */ 609 swap_maxpages = n * SWAP_META_PAGES; 610 swzone = n * sizeof(struct swblk); 611 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 612 printf("Cannot reserve swap pctrie zone, " 613 "reduce kern.maxswzone.\n"); 614 } 615 616 static vm_object_t 617 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 618 vm_ooffset_t offset) 619 { 620 vm_object_t object; 621 622 if (cred != NULL) { 623 if (!swap_reserve_by_cred(size, cred)) 624 return (NULL); 625 crhold(cred); 626 } 627 628 /* 629 * The un_pager.swp.swp_blks trie is initialized by 630 * vm_object_allocate() to ensure the correct order of 631 * visibility to other threads. 632 */ 633 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 634 PAGE_MASK + size)); 635 636 object->un_pager.swp.writemappings = 0; 637 object->handle = handle; 638 if (cred != NULL) { 639 object->cred = cred; 640 object->charge = size; 641 } 642 return (object); 643 } 644 645 /* 646 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 647 * its metadata structures. 648 * 649 * This routine is called from the mmap and fork code to create a new 650 * OBJT_SWAP object. 651 * 652 * This routine must ensure that no live duplicate is created for 653 * the named object request, which is protected against by 654 * holding the sw_alloc_sx lock in case handle != NULL. 655 */ 656 static vm_object_t 657 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 658 vm_ooffset_t offset, struct ucred *cred) 659 { 660 vm_object_t object; 661 662 if (handle != NULL) { 663 /* 664 * Reference existing named region or allocate new one. There 665 * should not be a race here against swp_pager_meta_build() 666 * as called from vm_page_remove() in regards to the lookup 667 * of the handle. 668 */ 669 sx_xlock(&sw_alloc_sx); 670 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 671 if (object == NULL) { 672 object = swap_pager_alloc_init(handle, cred, size, 673 offset); 674 if (object != NULL) { 675 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 676 object, pager_object_list); 677 } 678 } 679 sx_xunlock(&sw_alloc_sx); 680 } else { 681 object = swap_pager_alloc_init(handle, cred, size, offset); 682 } 683 return (object); 684 } 685 686 /* 687 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 688 * 689 * The swap backing for the object is destroyed. The code is 690 * designed such that we can reinstantiate it later, but this 691 * routine is typically called only when the entire object is 692 * about to be destroyed. 693 * 694 * The object must be locked. 695 */ 696 static void 697 swap_pager_dealloc(vm_object_t object) 698 { 699 700 VM_OBJECT_ASSERT_WLOCKED(object); 701 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 702 703 /* 704 * Remove from list right away so lookups will fail if we block for 705 * pageout completion. 706 */ 707 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 708 VM_OBJECT_WUNLOCK(object); 709 sx_xlock(&sw_alloc_sx); 710 TAILQ_REMOVE(NOBJLIST(object->handle), object, 711 pager_object_list); 712 sx_xunlock(&sw_alloc_sx); 713 VM_OBJECT_WLOCK(object); 714 } 715 716 vm_object_pip_wait(object, "swpdea"); 717 718 /* 719 * Free all remaining metadata. We only bother to free it from 720 * the swap meta data. We do not attempt to free swapblk's still 721 * associated with vm_page_t's for this object. We do not care 722 * if paging is still in progress on some objects. 723 */ 724 swp_pager_meta_free_all(object); 725 object->handle = NULL; 726 object->type = OBJT_DEAD; 727 } 728 729 /************************************************************************ 730 * SWAP PAGER BITMAP ROUTINES * 731 ************************************************************************/ 732 733 /* 734 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 735 * 736 * Allocate swap for up to the requested number of pages. The 737 * starting swap block number (a page index) is returned or 738 * SWAPBLK_NONE if the allocation failed. 739 * 740 * Also has the side effect of advising that somebody made a mistake 741 * when they configured swap and didn't configure enough. 742 * 743 * This routine may not sleep. 744 * 745 * We allocate in round-robin fashion from the configured devices. 746 */ 747 static daddr_t 748 swp_pager_getswapspace(int *io_npages) 749 { 750 daddr_t blk; 751 struct swdevt *sp; 752 int mpages, npages; 753 754 KASSERT(*io_npages >= 1, 755 ("%s: npages not positive", __func__)); 756 blk = SWAPBLK_NONE; 757 mpages = *io_npages; 758 npages = imin(BLIST_MAX_ALLOC, mpages); 759 mtx_lock(&sw_dev_mtx); 760 sp = swdevhd; 761 while (!TAILQ_EMPTY(&swtailq)) { 762 if (sp == NULL) 763 sp = TAILQ_FIRST(&swtailq); 764 if ((sp->sw_flags & SW_CLOSING) == 0) 765 blk = blist_alloc(sp->sw_blist, &npages, mpages); 766 if (blk != SWAPBLK_NONE) 767 break; 768 sp = TAILQ_NEXT(sp, sw_list); 769 if (swdevhd == sp) { 770 if (npages == 1) 771 break; 772 mpages = npages - 1; 773 npages >>= 1; 774 } 775 } 776 if (blk != SWAPBLK_NONE) { 777 *io_npages = npages; 778 blk += sp->sw_first; 779 sp->sw_used += npages; 780 swap_pager_avail -= npages; 781 swp_sizecheck(); 782 swdevhd = TAILQ_NEXT(sp, sw_list); 783 } else { 784 if (swap_pager_full != 2) { 785 printf("swp_pager_getswapspace(%d): failed\n", 786 *io_npages); 787 swap_pager_full = 2; 788 swap_pager_almost_full = 1; 789 } 790 swdevhd = NULL; 791 } 792 mtx_unlock(&sw_dev_mtx); 793 return (blk); 794 } 795 796 static bool 797 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 798 { 799 800 return (blk >= sp->sw_first && blk < sp->sw_end); 801 } 802 803 static void 804 swp_pager_strategy(struct buf *bp) 805 { 806 struct swdevt *sp; 807 808 mtx_lock(&sw_dev_mtx); 809 TAILQ_FOREACH(sp, &swtailq, sw_list) { 810 if (swp_pager_isondev(bp->b_blkno, sp)) { 811 mtx_unlock(&sw_dev_mtx); 812 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 813 unmapped_buf_allowed) { 814 bp->b_data = unmapped_buf; 815 bp->b_offset = 0; 816 } else { 817 pmap_qenter((vm_offset_t)bp->b_data, 818 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 819 } 820 sp->sw_strategy(bp, sp); 821 return; 822 } 823 } 824 panic("Swapdev not found"); 825 } 826 827 828 /* 829 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 830 * 831 * This routine returns the specified swap blocks back to the bitmap. 832 * 833 * This routine may not sleep. 834 */ 835 static void 836 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 837 { 838 struct swdevt *sp; 839 840 if (npages == 0) 841 return; 842 mtx_lock(&sw_dev_mtx); 843 TAILQ_FOREACH(sp, &swtailq, sw_list) { 844 if (swp_pager_isondev(blk, sp)) { 845 sp->sw_used -= npages; 846 /* 847 * If we are attempting to stop swapping on 848 * this device, we don't want to mark any 849 * blocks free lest they be reused. 850 */ 851 if ((sp->sw_flags & SW_CLOSING) == 0) { 852 blist_free(sp->sw_blist, blk - sp->sw_first, 853 npages); 854 swap_pager_avail += npages; 855 swp_sizecheck(); 856 } 857 mtx_unlock(&sw_dev_mtx); 858 return; 859 } 860 } 861 panic("Swapdev not found"); 862 } 863 864 /* 865 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 866 */ 867 static int 868 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 869 { 870 struct sbuf sbuf; 871 struct swdevt *sp; 872 const char *devname; 873 int error; 874 875 error = sysctl_wire_old_buffer(req, 0); 876 if (error != 0) 877 return (error); 878 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 879 mtx_lock(&sw_dev_mtx); 880 TAILQ_FOREACH(sp, &swtailq, sw_list) { 881 if (vn_isdisk(sp->sw_vp, NULL)) 882 devname = devtoname(sp->sw_vp->v_rdev); 883 else 884 devname = "[file]"; 885 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 886 blist_stats(sp->sw_blist, &sbuf); 887 } 888 mtx_unlock(&sw_dev_mtx); 889 error = sbuf_finish(&sbuf); 890 sbuf_delete(&sbuf); 891 return (error); 892 } 893 894 /* 895 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 896 * range within an object. 897 * 898 * This is a globally accessible routine. 899 * 900 * This routine removes swapblk assignments from swap metadata. 901 * 902 * The external callers of this routine typically have already destroyed 903 * or renamed vm_page_t's associated with this range in the object so 904 * we should be ok. 905 * 906 * The object must be locked. 907 */ 908 void 909 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 910 { 911 912 swp_pager_meta_free(object, start, size); 913 } 914 915 /* 916 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 917 * 918 * Assigns swap blocks to the specified range within the object. The 919 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 920 * 921 * Returns 0 on success, -1 on failure. 922 */ 923 int 924 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 925 { 926 daddr_t addr, blk, n_free, s_free; 927 int i, j, n; 928 929 swp_pager_init_freerange(&s_free, &n_free); 930 VM_OBJECT_WLOCK(object); 931 for (i = 0; i < size; i += n) { 932 n = size - i; 933 blk = swp_pager_getswapspace(&n); 934 if (blk == SWAPBLK_NONE) { 935 swp_pager_meta_free(object, start, i); 936 VM_OBJECT_WUNLOCK(object); 937 return (-1); 938 } 939 for (j = 0; j < n; ++j) { 940 addr = swp_pager_meta_build(object, 941 start + i + j, blk + j); 942 if (addr != SWAPBLK_NONE) 943 swp_pager_update_freerange(&s_free, &n_free, 944 addr); 945 } 946 } 947 swp_pager_freeswapspace(s_free, n_free); 948 VM_OBJECT_WUNLOCK(object); 949 return (0); 950 } 951 952 static bool 953 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 954 vm_pindex_t pindex, daddr_t addr) 955 { 956 daddr_t dstaddr; 957 958 KASSERT(srcobject->type == OBJT_SWAP, 959 ("%s: Srcobject not swappable", __func__)); 960 if (dstobject->type == OBJT_SWAP && 961 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 962 /* Caller should destroy the source block. */ 963 return (false); 964 } 965 966 /* 967 * Destination has no swapblk and is not resident, transfer source. 968 * swp_pager_meta_build() can sleep. 969 */ 970 VM_OBJECT_WUNLOCK(srcobject); 971 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 972 KASSERT(dstaddr == SWAPBLK_NONE, 973 ("Unexpected destination swapblk")); 974 VM_OBJECT_WLOCK(srcobject); 975 976 return (true); 977 } 978 979 /* 980 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 981 * and destroy the source. 982 * 983 * Copy any valid swapblks from the source to the destination. In 984 * cases where both the source and destination have a valid swapblk, 985 * we keep the destination's. 986 * 987 * This routine is allowed to sleep. It may sleep allocating metadata 988 * indirectly through swp_pager_meta_build(). 989 * 990 * The source object contains no vm_page_t's (which is just as well) 991 * 992 * The source object is of type OBJT_SWAP. 993 * 994 * The source and destination objects must be locked. 995 * Both object locks may temporarily be released. 996 */ 997 void 998 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 999 vm_pindex_t offset, int destroysource) 1000 { 1001 1002 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1003 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1004 1005 /* 1006 * If destroysource is set, we remove the source object from the 1007 * swap_pager internal queue now. 1008 */ 1009 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1010 srcobject->handle != NULL) { 1011 VM_OBJECT_WUNLOCK(srcobject); 1012 VM_OBJECT_WUNLOCK(dstobject); 1013 sx_xlock(&sw_alloc_sx); 1014 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1015 pager_object_list); 1016 sx_xunlock(&sw_alloc_sx); 1017 VM_OBJECT_WLOCK(dstobject); 1018 VM_OBJECT_WLOCK(srcobject); 1019 } 1020 1021 /* 1022 * Transfer source to destination. 1023 */ 1024 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1025 1026 /* 1027 * Free left over swap blocks in source. 1028 * 1029 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1030 * double-remove the object from the swap queues. 1031 */ 1032 if (destroysource) { 1033 swp_pager_meta_free_all(srcobject); 1034 /* 1035 * Reverting the type is not necessary, the caller is going 1036 * to destroy srcobject directly, but I'm doing it here 1037 * for consistency since we've removed the object from its 1038 * queues. 1039 */ 1040 srcobject->type = OBJT_DEFAULT; 1041 } 1042 } 1043 1044 /* 1045 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1046 * the requested page. 1047 * 1048 * We determine whether good backing store exists for the requested 1049 * page and return TRUE if it does, FALSE if it doesn't. 1050 * 1051 * If TRUE, we also try to determine how much valid, contiguous backing 1052 * store exists before and after the requested page. 1053 */ 1054 static boolean_t 1055 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1056 int *after) 1057 { 1058 daddr_t blk, blk0; 1059 int i; 1060 1061 VM_OBJECT_ASSERT_LOCKED(object); 1062 KASSERT(object->type == OBJT_SWAP, 1063 ("%s: object not swappable", __func__)); 1064 1065 /* 1066 * do we have good backing store at the requested index ? 1067 */ 1068 blk0 = swp_pager_meta_lookup(object, pindex); 1069 if (blk0 == SWAPBLK_NONE) { 1070 if (before) 1071 *before = 0; 1072 if (after) 1073 *after = 0; 1074 return (FALSE); 1075 } 1076 1077 /* 1078 * find backwards-looking contiguous good backing store 1079 */ 1080 if (before != NULL) { 1081 for (i = 1; i < SWB_NPAGES; i++) { 1082 if (i > pindex) 1083 break; 1084 blk = swp_pager_meta_lookup(object, pindex - i); 1085 if (blk != blk0 - i) 1086 break; 1087 } 1088 *before = i - 1; 1089 } 1090 1091 /* 1092 * find forward-looking contiguous good backing store 1093 */ 1094 if (after != NULL) { 1095 for (i = 1; i < SWB_NPAGES; i++) { 1096 blk = swp_pager_meta_lookup(object, pindex + i); 1097 if (blk != blk0 + i) 1098 break; 1099 } 1100 *after = i - 1; 1101 } 1102 return (TRUE); 1103 } 1104 1105 /* 1106 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1107 * 1108 * This removes any associated swap backing store, whether valid or 1109 * not, from the page. 1110 * 1111 * This routine is typically called when a page is made dirty, at 1112 * which point any associated swap can be freed. MADV_FREE also 1113 * calls us in a special-case situation 1114 * 1115 * NOTE!!! If the page is clean and the swap was valid, the caller 1116 * should make the page dirty before calling this routine. This routine 1117 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1118 * depends on it. 1119 * 1120 * This routine may not sleep. 1121 * 1122 * The object containing the page may be locked. 1123 */ 1124 static void 1125 swap_pager_unswapped(vm_page_t m) 1126 { 1127 struct swblk *sb; 1128 vm_object_t obj; 1129 1130 /* 1131 * Handle enqueing deferred frees first. If we do not have the 1132 * object lock we wait for the page daemon to clear the space. 1133 */ 1134 obj = m->object; 1135 if (!VM_OBJECT_WOWNED(obj)) { 1136 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1137 /* 1138 * The caller is responsible for synchronization but we 1139 * will harmlessly handle races. This is typically provided 1140 * by only calling unswapped() when a page transitions from 1141 * clean to dirty. 1142 */ 1143 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1144 PGA_SWAP_SPACE) { 1145 vm_page_aflag_set(m, PGA_SWAP_FREE); 1146 counter_u64_add(swap_free_deferred, 1); 1147 } 1148 return; 1149 } 1150 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1151 counter_u64_add(swap_free_completed, 1); 1152 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1153 1154 /* 1155 * The meta data only exists if the object is OBJT_SWAP 1156 * and even then might not be allocated yet. 1157 */ 1158 KASSERT(m->object->type == OBJT_SWAP, 1159 ("Free object not swappable")); 1160 1161 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1162 rounddown(m->pindex, SWAP_META_PAGES)); 1163 if (sb == NULL) 1164 return; 1165 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1166 return; 1167 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1168 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1169 swp_pager_free_empty_swblk(m->object, sb); 1170 } 1171 1172 /* 1173 * swap_pager_getpages() - bring pages in from swap 1174 * 1175 * Attempt to page in the pages in array "ma" of length "count". The 1176 * caller may optionally specify that additional pages preceding and 1177 * succeeding the specified range be paged in. The number of such pages 1178 * is returned in the "rbehind" and "rahead" parameters, and they will 1179 * be in the inactive queue upon return. 1180 * 1181 * The pages in "ma" must be busied and will remain busied upon return. 1182 */ 1183 static int 1184 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1185 int *rbehind, int *rahead) 1186 { 1187 struct buf *bp; 1188 vm_page_t bm, mpred, msucc, p; 1189 vm_pindex_t pindex; 1190 daddr_t blk; 1191 int i, maxahead, maxbehind, reqcount; 1192 1193 VM_OBJECT_ASSERT_WLOCKED(object); 1194 reqcount = count; 1195 1196 KASSERT(object->type == OBJT_SWAP, 1197 ("%s: object not swappable", __func__)); 1198 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1199 VM_OBJECT_WUNLOCK(object); 1200 return (VM_PAGER_FAIL); 1201 } 1202 1203 KASSERT(reqcount - 1 <= maxahead, 1204 ("page count %d extends beyond swap block", reqcount)); 1205 1206 /* 1207 * Do not transfer any pages other than those that are xbusied 1208 * when running during a split or collapse operation. This 1209 * prevents clustering from re-creating pages which are being 1210 * moved into another object. 1211 */ 1212 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1213 maxahead = reqcount - 1; 1214 maxbehind = 0; 1215 } 1216 1217 /* 1218 * Clip the readahead and readbehind ranges to exclude resident pages. 1219 */ 1220 if (rahead != NULL) { 1221 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1222 pindex = ma[reqcount - 1]->pindex; 1223 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1224 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1225 *rahead = msucc->pindex - pindex - 1; 1226 } 1227 if (rbehind != NULL) { 1228 *rbehind = imin(*rbehind, maxbehind); 1229 pindex = ma[0]->pindex; 1230 mpred = TAILQ_PREV(ma[0], pglist, listq); 1231 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1232 *rbehind = pindex - mpred->pindex - 1; 1233 } 1234 1235 bm = ma[0]; 1236 for (i = 0; i < count; i++) 1237 ma[i]->oflags |= VPO_SWAPINPROG; 1238 1239 /* 1240 * Allocate readahead and readbehind pages. 1241 */ 1242 if (rbehind != NULL) { 1243 for (i = 1; i <= *rbehind; i++) { 1244 p = vm_page_alloc(object, ma[0]->pindex - i, 1245 VM_ALLOC_NORMAL); 1246 if (p == NULL) 1247 break; 1248 p->oflags |= VPO_SWAPINPROG; 1249 bm = p; 1250 } 1251 *rbehind = i - 1; 1252 } 1253 if (rahead != NULL) { 1254 for (i = 0; i < *rahead; i++) { 1255 p = vm_page_alloc(object, 1256 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1257 if (p == NULL) 1258 break; 1259 p->oflags |= VPO_SWAPINPROG; 1260 } 1261 *rahead = i; 1262 } 1263 if (rbehind != NULL) 1264 count += *rbehind; 1265 if (rahead != NULL) 1266 count += *rahead; 1267 1268 vm_object_pip_add(object, count); 1269 1270 pindex = bm->pindex; 1271 blk = swp_pager_meta_lookup(object, pindex); 1272 KASSERT(blk != SWAPBLK_NONE, 1273 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1274 1275 VM_OBJECT_WUNLOCK(object); 1276 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1277 /* Pages cannot leave the object while busy. */ 1278 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1279 MPASS(p->pindex == bm->pindex + i); 1280 bp->b_pages[i] = p; 1281 } 1282 1283 bp->b_flags |= B_PAGING; 1284 bp->b_iocmd = BIO_READ; 1285 bp->b_iodone = swp_pager_async_iodone; 1286 bp->b_rcred = crhold(thread0.td_ucred); 1287 bp->b_wcred = crhold(thread0.td_ucred); 1288 bp->b_blkno = blk; 1289 bp->b_bcount = PAGE_SIZE * count; 1290 bp->b_bufsize = PAGE_SIZE * count; 1291 bp->b_npages = count; 1292 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1293 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1294 1295 VM_CNT_INC(v_swapin); 1296 VM_CNT_ADD(v_swappgsin, count); 1297 1298 /* 1299 * perform the I/O. NOTE!!! bp cannot be considered valid after 1300 * this point because we automatically release it on completion. 1301 * Instead, we look at the one page we are interested in which we 1302 * still hold a lock on even through the I/O completion. 1303 * 1304 * The other pages in our ma[] array are also released on completion, 1305 * so we cannot assume they are valid anymore either. 1306 * 1307 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1308 */ 1309 BUF_KERNPROC(bp); 1310 swp_pager_strategy(bp); 1311 1312 /* 1313 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1314 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1315 * is set in the metadata for each page in the request. 1316 */ 1317 VM_OBJECT_WLOCK(object); 1318 /* This could be implemented more efficiently with aflags */ 1319 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1320 ma[0]->oflags |= VPO_SWAPSLEEP; 1321 VM_CNT_INC(v_intrans); 1322 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1323 "swread", hz * 20)) { 1324 printf( 1325 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1326 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1327 } 1328 } 1329 VM_OBJECT_WUNLOCK(object); 1330 1331 /* 1332 * If we had an unrecoverable read error pages will not be valid. 1333 */ 1334 for (i = 0; i < reqcount; i++) 1335 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1336 return (VM_PAGER_ERROR); 1337 1338 return (VM_PAGER_OK); 1339 1340 /* 1341 * A final note: in a low swap situation, we cannot deallocate swap 1342 * and mark a page dirty here because the caller is likely to mark 1343 * the page clean when we return, causing the page to possibly revert 1344 * to all-zero's later. 1345 */ 1346 } 1347 1348 static int 1349 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1350 int *rbehind, int *rahead) 1351 { 1352 1353 VM_OBJECT_WLOCK(object); 1354 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1355 } 1356 1357 /* 1358 * swap_pager_getpages_async(): 1359 * 1360 * Right now this is emulation of asynchronous operation on top of 1361 * swap_pager_getpages(). 1362 */ 1363 static int 1364 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1365 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1366 { 1367 int r, error; 1368 1369 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1370 switch (r) { 1371 case VM_PAGER_OK: 1372 error = 0; 1373 break; 1374 case VM_PAGER_ERROR: 1375 error = EIO; 1376 break; 1377 case VM_PAGER_FAIL: 1378 error = EINVAL; 1379 break; 1380 default: 1381 panic("unhandled swap_pager_getpages() error %d", r); 1382 } 1383 (iodone)(arg, ma, count, error); 1384 1385 return (r); 1386 } 1387 1388 /* 1389 * swap_pager_putpages: 1390 * 1391 * Assign swap (if necessary) and initiate I/O on the specified pages. 1392 * 1393 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1394 * are automatically converted to SWAP objects. 1395 * 1396 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1397 * vm_page reservation system coupled with properly written VFS devices 1398 * should ensure that no low-memory deadlock occurs. This is an area 1399 * which needs work. 1400 * 1401 * The parent has N vm_object_pip_add() references prior to 1402 * calling us and will remove references for rtvals[] that are 1403 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1404 * completion. 1405 * 1406 * The parent has soft-busy'd the pages it passes us and will unbusy 1407 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1408 * We need to unbusy the rest on I/O completion. 1409 */ 1410 static void 1411 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1412 int flags, int *rtvals) 1413 { 1414 struct buf *bp; 1415 daddr_t addr, blk, n_free, s_free; 1416 vm_page_t mreq; 1417 int i, j, n; 1418 bool async; 1419 1420 KASSERT(count == 0 || ma[0]->object == object, 1421 ("%s: object mismatch %p/%p", 1422 __func__, object, ma[0]->object)); 1423 1424 /* 1425 * Step 1 1426 * 1427 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1428 */ 1429 if (object->type != OBJT_SWAP) { 1430 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1431 KASSERT(addr == SWAPBLK_NONE, 1432 ("unexpected object swap block")); 1433 } 1434 VM_OBJECT_WUNLOCK(object); 1435 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1436 swp_pager_init_freerange(&s_free, &n_free); 1437 1438 /* 1439 * Step 2 1440 * 1441 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1442 * The page is left dirty until the pageout operation completes 1443 * successfully. 1444 */ 1445 for (i = 0; i < count; i += n) { 1446 /* Maximum I/O size is limited by maximum swap block size. */ 1447 n = min(count - i, nsw_cluster_max); 1448 1449 if (async) { 1450 mtx_lock(&swbuf_mtx); 1451 while (nsw_wcount_async == 0) 1452 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1453 "swbufa", 0); 1454 nsw_wcount_async--; 1455 mtx_unlock(&swbuf_mtx); 1456 } 1457 1458 /* Get a block of swap of size up to size n. */ 1459 VM_OBJECT_WLOCK(object); 1460 blk = swp_pager_getswapspace(&n); 1461 if (blk == SWAPBLK_NONE) { 1462 VM_OBJECT_WUNLOCK(object); 1463 mtx_lock(&swbuf_mtx); 1464 if (++nsw_wcount_async == 1) 1465 wakeup(&nsw_wcount_async); 1466 mtx_unlock(&swbuf_mtx); 1467 for (j = 0; j < n; ++j) 1468 rtvals[i + j] = VM_PAGER_FAIL; 1469 continue; 1470 } 1471 for (j = 0; j < n; ++j) { 1472 mreq = ma[i + j]; 1473 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1474 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1475 blk + j); 1476 if (addr != SWAPBLK_NONE) 1477 swp_pager_update_freerange(&s_free, &n_free, 1478 addr); 1479 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1480 mreq->oflags |= VPO_SWAPINPROG; 1481 } 1482 VM_OBJECT_WUNLOCK(object); 1483 1484 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1485 if (async) 1486 bp->b_flags = B_ASYNC; 1487 bp->b_flags |= B_PAGING; 1488 bp->b_iocmd = BIO_WRITE; 1489 1490 bp->b_rcred = crhold(thread0.td_ucred); 1491 bp->b_wcred = crhold(thread0.td_ucred); 1492 bp->b_bcount = PAGE_SIZE * n; 1493 bp->b_bufsize = PAGE_SIZE * n; 1494 bp->b_blkno = blk; 1495 for (j = 0; j < n; j++) 1496 bp->b_pages[j] = ma[i + j]; 1497 bp->b_npages = n; 1498 1499 /* 1500 * Must set dirty range for NFS to work. 1501 */ 1502 bp->b_dirtyoff = 0; 1503 bp->b_dirtyend = bp->b_bcount; 1504 1505 VM_CNT_INC(v_swapout); 1506 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1507 1508 /* 1509 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1510 * can call the async completion routine at the end of a 1511 * synchronous I/O operation. Otherwise, our caller would 1512 * perform duplicate unbusy and wakeup operations on the page 1513 * and object, respectively. 1514 */ 1515 for (j = 0; j < n; j++) 1516 rtvals[i + j] = VM_PAGER_PEND; 1517 1518 /* 1519 * asynchronous 1520 * 1521 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1522 */ 1523 if (async) { 1524 bp->b_iodone = swp_pager_async_iodone; 1525 BUF_KERNPROC(bp); 1526 swp_pager_strategy(bp); 1527 continue; 1528 } 1529 1530 /* 1531 * synchronous 1532 * 1533 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1534 */ 1535 bp->b_iodone = bdone; 1536 swp_pager_strategy(bp); 1537 1538 /* 1539 * Wait for the sync I/O to complete. 1540 */ 1541 bwait(bp, PVM, "swwrt"); 1542 1543 /* 1544 * Now that we are through with the bp, we can call the 1545 * normal async completion, which frees everything up. 1546 */ 1547 swp_pager_async_iodone(bp); 1548 } 1549 swp_pager_freeswapspace(s_free, n_free); 1550 VM_OBJECT_WLOCK(object); 1551 } 1552 1553 /* 1554 * swp_pager_async_iodone: 1555 * 1556 * Completion routine for asynchronous reads and writes from/to swap. 1557 * Also called manually by synchronous code to finish up a bp. 1558 * 1559 * This routine may not sleep. 1560 */ 1561 static void 1562 swp_pager_async_iodone(struct buf *bp) 1563 { 1564 int i; 1565 vm_object_t object = NULL; 1566 1567 /* 1568 * Report error - unless we ran out of memory, in which case 1569 * we've already logged it in swapgeom_strategy(). 1570 */ 1571 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1572 printf( 1573 "swap_pager: I/O error - %s failed; blkno %ld," 1574 "size %ld, error %d\n", 1575 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1576 (long)bp->b_blkno, 1577 (long)bp->b_bcount, 1578 bp->b_error 1579 ); 1580 } 1581 1582 /* 1583 * remove the mapping for kernel virtual 1584 */ 1585 if (buf_mapped(bp)) 1586 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1587 else 1588 bp->b_data = bp->b_kvabase; 1589 1590 if (bp->b_npages) { 1591 object = bp->b_pages[0]->object; 1592 VM_OBJECT_WLOCK(object); 1593 } 1594 1595 /* 1596 * cleanup pages. If an error occurs writing to swap, we are in 1597 * very serious trouble. If it happens to be a disk error, though, 1598 * we may be able to recover by reassigning the swap later on. So 1599 * in this case we remove the m->swapblk assignment for the page 1600 * but do not free it in the rlist. The errornous block(s) are thus 1601 * never reallocated as swap. Redirty the page and continue. 1602 */ 1603 for (i = 0; i < bp->b_npages; ++i) { 1604 vm_page_t m = bp->b_pages[i]; 1605 1606 m->oflags &= ~VPO_SWAPINPROG; 1607 if (m->oflags & VPO_SWAPSLEEP) { 1608 m->oflags &= ~VPO_SWAPSLEEP; 1609 wakeup(&object->handle); 1610 } 1611 1612 /* We always have space after I/O, successful or not. */ 1613 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1614 1615 if (bp->b_ioflags & BIO_ERROR) { 1616 /* 1617 * If an error occurs I'd love to throw the swapblk 1618 * away without freeing it back to swapspace, so it 1619 * can never be used again. But I can't from an 1620 * interrupt. 1621 */ 1622 if (bp->b_iocmd == BIO_READ) { 1623 /* 1624 * NOTE: for reads, m->dirty will probably 1625 * be overridden by the original caller of 1626 * getpages so don't play cute tricks here. 1627 */ 1628 vm_page_invalid(m); 1629 } else { 1630 /* 1631 * If a write error occurs, reactivate page 1632 * so it doesn't clog the inactive list, 1633 * then finish the I/O. 1634 */ 1635 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1636 1637 /* PQ_UNSWAPPABLE? */ 1638 vm_page_activate(m); 1639 vm_page_sunbusy(m); 1640 } 1641 } else if (bp->b_iocmd == BIO_READ) { 1642 /* 1643 * NOTE: for reads, m->dirty will probably be 1644 * overridden by the original caller of getpages so 1645 * we cannot set them in order to free the underlying 1646 * swap in a low-swap situation. I don't think we'd 1647 * want to do that anyway, but it was an optimization 1648 * that existed in the old swapper for a time before 1649 * it got ripped out due to precisely this problem. 1650 */ 1651 KASSERT(!pmap_page_is_mapped(m), 1652 ("swp_pager_async_iodone: page %p is mapped", m)); 1653 KASSERT(m->dirty == 0, 1654 ("swp_pager_async_iodone: page %p is dirty", m)); 1655 1656 vm_page_valid(m); 1657 if (i < bp->b_pgbefore || 1658 i >= bp->b_npages - bp->b_pgafter) 1659 vm_page_readahead_finish(m); 1660 } else { 1661 /* 1662 * For write success, clear the dirty 1663 * status, then finish the I/O ( which decrements the 1664 * busy count and possibly wakes waiter's up ). 1665 * A page is only written to swap after a period of 1666 * inactivity. Therefore, we do not expect it to be 1667 * reused. 1668 */ 1669 KASSERT(!pmap_page_is_write_mapped(m), 1670 ("swp_pager_async_iodone: page %p is not write" 1671 " protected", m)); 1672 vm_page_undirty(m); 1673 vm_page_deactivate_noreuse(m); 1674 vm_page_sunbusy(m); 1675 } 1676 } 1677 1678 /* 1679 * adjust pip. NOTE: the original parent may still have its own 1680 * pip refs on the object. 1681 */ 1682 if (object != NULL) { 1683 vm_object_pip_wakeupn(object, bp->b_npages); 1684 VM_OBJECT_WUNLOCK(object); 1685 } 1686 1687 /* 1688 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1689 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1690 * trigger a KASSERT in relpbuf(). 1691 */ 1692 if (bp->b_vp) { 1693 bp->b_vp = NULL; 1694 bp->b_bufobj = NULL; 1695 } 1696 /* 1697 * release the physical I/O buffer 1698 */ 1699 if (bp->b_flags & B_ASYNC) { 1700 mtx_lock(&swbuf_mtx); 1701 if (++nsw_wcount_async == 1) 1702 wakeup(&nsw_wcount_async); 1703 mtx_unlock(&swbuf_mtx); 1704 } 1705 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1706 } 1707 1708 int 1709 swap_pager_nswapdev(void) 1710 { 1711 1712 return (nswapdev); 1713 } 1714 1715 static void 1716 swp_pager_force_dirty(vm_page_t m) 1717 { 1718 1719 vm_page_dirty(m); 1720 swap_pager_unswapped(m); 1721 vm_page_launder(m); 1722 } 1723 1724 /* 1725 * swap_pager_swapoff_object: 1726 * 1727 * Page in all of the pages that have been paged out for an object 1728 * to a swap device. 1729 */ 1730 static void 1731 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1732 { 1733 struct swblk *sb; 1734 vm_page_t m; 1735 vm_pindex_t pi; 1736 daddr_t blk; 1737 int i, nv, rahead, rv; 1738 1739 KASSERT(object->type == OBJT_SWAP, 1740 ("%s: Object not swappable", __func__)); 1741 1742 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1743 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1744 if ((object->flags & OBJ_DEAD) != 0) { 1745 /* 1746 * Make sure that pending writes finish before 1747 * returning. 1748 */ 1749 vm_object_pip_wait(object, "swpoff"); 1750 swp_pager_meta_free_all(object); 1751 break; 1752 } 1753 for (i = 0; i < SWAP_META_PAGES; i++) { 1754 /* 1755 * Count the number of contiguous valid blocks. 1756 */ 1757 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) { 1758 blk = sb->d[i + nv]; 1759 if (!swp_pager_isondev(blk, sp) || 1760 blk == SWAPBLK_NONE) 1761 break; 1762 } 1763 if (nv == 0) 1764 continue; 1765 1766 /* 1767 * Look for a page corresponding to the first 1768 * valid block and ensure that any pending paging 1769 * operations on it are complete. If the page is valid, 1770 * mark it dirty and free the swap block. Try to batch 1771 * this operation since it may cause sp to be freed, 1772 * meaning that we must restart the scan. Avoid busying 1773 * valid pages since we may block forever on kernel 1774 * stack pages. 1775 */ 1776 m = vm_page_lookup(object, sb->p + i); 1777 if (m == NULL) { 1778 m = vm_page_alloc(object, sb->p + i, 1779 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 1780 if (m == NULL) 1781 break; 1782 } else { 1783 if ((m->oflags & VPO_SWAPINPROG) != 0) { 1784 m->oflags |= VPO_SWAPSLEEP; 1785 VM_OBJECT_SLEEP(object, &object->handle, 1786 PSWP, "swpoff", 0); 1787 break; 1788 } 1789 if (vm_page_all_valid(m)) { 1790 do { 1791 swp_pager_force_dirty(m); 1792 } while (--nv > 0 && 1793 (m = vm_page_next(m)) != NULL && 1794 vm_page_all_valid(m) && 1795 (m->oflags & VPO_SWAPINPROG) == 0); 1796 break; 1797 } 1798 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1799 break; 1800 } 1801 1802 vm_object_pip_add(object, 1); 1803 rahead = SWAP_META_PAGES; 1804 rv = swap_pager_getpages_locked(object, &m, 1, NULL, 1805 &rahead); 1806 if (rv != VM_PAGER_OK) 1807 panic("%s: read from swap failed: %d", 1808 __func__, rv); 1809 vm_object_pip_wakeupn(object, 1); 1810 VM_OBJECT_WLOCK(object); 1811 vm_page_xunbusy(m); 1812 1813 /* 1814 * The object lock was dropped so we must restart the 1815 * scan of this swap block. Pages paged in during this 1816 * iteration will be marked dirty in a future iteration. 1817 */ 1818 break; 1819 } 1820 if (i == SWAP_META_PAGES) 1821 pi = sb->p + SWAP_META_PAGES; 1822 } 1823 } 1824 1825 /* 1826 * swap_pager_swapoff: 1827 * 1828 * Page in all of the pages that have been paged out to the 1829 * given device. The corresponding blocks in the bitmap must be 1830 * marked as allocated and the device must be flagged SW_CLOSING. 1831 * There may be no processes swapped out to the device. 1832 * 1833 * This routine may block. 1834 */ 1835 static void 1836 swap_pager_swapoff(struct swdevt *sp) 1837 { 1838 vm_object_t object; 1839 int retries; 1840 1841 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1842 1843 retries = 0; 1844 full_rescan: 1845 mtx_lock(&vm_object_list_mtx); 1846 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1847 if (object->type != OBJT_SWAP) 1848 continue; 1849 mtx_unlock(&vm_object_list_mtx); 1850 /* Depends on type-stability. */ 1851 VM_OBJECT_WLOCK(object); 1852 1853 /* 1854 * Dead objects are eventually terminated on their own. 1855 */ 1856 if ((object->flags & OBJ_DEAD) != 0) 1857 goto next_obj; 1858 1859 /* 1860 * Sync with fences placed after pctrie 1861 * initialization. We must not access pctrie below 1862 * unless we checked that our object is swap and not 1863 * dead. 1864 */ 1865 atomic_thread_fence_acq(); 1866 if (object->type != OBJT_SWAP) 1867 goto next_obj; 1868 1869 swap_pager_swapoff_object(sp, object); 1870 next_obj: 1871 VM_OBJECT_WUNLOCK(object); 1872 mtx_lock(&vm_object_list_mtx); 1873 } 1874 mtx_unlock(&vm_object_list_mtx); 1875 1876 if (sp->sw_used) { 1877 /* 1878 * Objects may be locked or paging to the device being 1879 * removed, so we will miss their pages and need to 1880 * make another pass. We have marked this device as 1881 * SW_CLOSING, so the activity should finish soon. 1882 */ 1883 retries++; 1884 if (retries > 100) { 1885 panic("swapoff: failed to locate %d swap blocks", 1886 sp->sw_used); 1887 } 1888 pause("swpoff", hz / 20); 1889 goto full_rescan; 1890 } 1891 EVENTHANDLER_INVOKE(swapoff, sp); 1892 } 1893 1894 /************************************************************************ 1895 * SWAP META DATA * 1896 ************************************************************************ 1897 * 1898 * These routines manipulate the swap metadata stored in the 1899 * OBJT_SWAP object. 1900 * 1901 * Swap metadata is implemented with a global hash and not directly 1902 * linked into the object. Instead the object simply contains 1903 * appropriate tracking counters. 1904 */ 1905 1906 /* 1907 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1908 */ 1909 static bool 1910 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1911 { 1912 int i; 1913 1914 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1915 for (i = start; i < limit; i++) { 1916 if (sb->d[i] != SWAPBLK_NONE) 1917 return (false); 1918 } 1919 return (true); 1920 } 1921 1922 /* 1923 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1924 * 1925 * Nothing is done if the block is still in use. 1926 */ 1927 static void 1928 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1929 { 1930 1931 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1932 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1933 uma_zfree(swblk_zone, sb); 1934 } 1935 } 1936 1937 /* 1938 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1939 * 1940 * We first convert the object to a swap object if it is a default 1941 * object. 1942 * 1943 * The specified swapblk is added to the object's swap metadata. If 1944 * the swapblk is not valid, it is freed instead. Any previously 1945 * assigned swapblk is returned. 1946 */ 1947 static daddr_t 1948 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1949 { 1950 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1951 struct swblk *sb, *sb1; 1952 vm_pindex_t modpi, rdpi; 1953 daddr_t prev_swapblk; 1954 int error, i; 1955 1956 VM_OBJECT_ASSERT_WLOCKED(object); 1957 1958 /* 1959 * Convert default object to swap object if necessary 1960 */ 1961 if (object->type != OBJT_SWAP) { 1962 pctrie_init(&object->un_pager.swp.swp_blks); 1963 1964 /* 1965 * Ensure that swap_pager_swapoff()'s iteration over 1966 * object_list does not see a garbage pctrie. 1967 */ 1968 atomic_thread_fence_rel(); 1969 1970 object->type = OBJT_SWAP; 1971 object->un_pager.swp.writemappings = 0; 1972 KASSERT((object->flags & OBJ_ANON) != 0 || 1973 object->handle == NULL, 1974 ("default pager %p with handle %p", 1975 object, object->handle)); 1976 } 1977 1978 rdpi = rounddown(pindex, SWAP_META_PAGES); 1979 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1980 if (sb == NULL) { 1981 if (swapblk == SWAPBLK_NONE) 1982 return (SWAPBLK_NONE); 1983 for (;;) { 1984 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1985 pageproc ? M_USE_RESERVE : 0)); 1986 if (sb != NULL) { 1987 sb->p = rdpi; 1988 for (i = 0; i < SWAP_META_PAGES; i++) 1989 sb->d[i] = SWAPBLK_NONE; 1990 if (atomic_cmpset_int(&swblk_zone_exhausted, 1991 1, 0)) 1992 printf("swblk zone ok\n"); 1993 break; 1994 } 1995 VM_OBJECT_WUNLOCK(object); 1996 if (uma_zone_exhausted(swblk_zone)) { 1997 if (atomic_cmpset_int(&swblk_zone_exhausted, 1998 0, 1)) 1999 printf("swap blk zone exhausted, " 2000 "increase kern.maxswzone\n"); 2001 vm_pageout_oom(VM_OOM_SWAPZ); 2002 pause("swzonxb", 10); 2003 } else 2004 uma_zwait(swblk_zone); 2005 VM_OBJECT_WLOCK(object); 2006 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2007 rdpi); 2008 if (sb != NULL) 2009 /* 2010 * Somebody swapped out a nearby page, 2011 * allocating swblk at the rdpi index, 2012 * while we dropped the object lock. 2013 */ 2014 goto allocated; 2015 } 2016 for (;;) { 2017 error = SWAP_PCTRIE_INSERT( 2018 &object->un_pager.swp.swp_blks, sb); 2019 if (error == 0) { 2020 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2021 1, 0)) 2022 printf("swpctrie zone ok\n"); 2023 break; 2024 } 2025 VM_OBJECT_WUNLOCK(object); 2026 if (uma_zone_exhausted(swpctrie_zone)) { 2027 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2028 0, 1)) 2029 printf("swap pctrie zone exhausted, " 2030 "increase kern.maxswzone\n"); 2031 vm_pageout_oom(VM_OOM_SWAPZ); 2032 pause("swzonxp", 10); 2033 } else 2034 uma_zwait(swpctrie_zone); 2035 VM_OBJECT_WLOCK(object); 2036 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2037 rdpi); 2038 if (sb1 != NULL) { 2039 uma_zfree(swblk_zone, sb); 2040 sb = sb1; 2041 goto allocated; 2042 } 2043 } 2044 } 2045 allocated: 2046 MPASS(sb->p == rdpi); 2047 2048 modpi = pindex % SWAP_META_PAGES; 2049 /* Return prior contents of metadata. */ 2050 prev_swapblk = sb->d[modpi]; 2051 /* Enter block into metadata. */ 2052 sb->d[modpi] = swapblk; 2053 2054 /* 2055 * Free the swblk if we end up with the empty page run. 2056 */ 2057 if (swapblk == SWAPBLK_NONE) 2058 swp_pager_free_empty_swblk(object, sb); 2059 return (prev_swapblk); 2060 } 2061 2062 /* 2063 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2064 * metadata, or transfer it into dstobject. 2065 * 2066 * This routine will free swap metadata structures as they are cleaned 2067 * out. 2068 */ 2069 static void 2070 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2071 vm_pindex_t pindex, vm_pindex_t count) 2072 { 2073 struct swblk *sb; 2074 daddr_t n_free, s_free; 2075 vm_pindex_t offset, last; 2076 int i, limit, start; 2077 2078 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2079 if (srcobject->type != OBJT_SWAP || count == 0) 2080 return; 2081 2082 swp_pager_init_freerange(&s_free, &n_free); 2083 offset = pindex; 2084 last = pindex + count; 2085 for (;;) { 2086 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2087 rounddown(pindex, SWAP_META_PAGES)); 2088 if (sb == NULL || sb->p >= last) 2089 break; 2090 start = pindex > sb->p ? pindex - sb->p : 0; 2091 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2092 SWAP_META_PAGES; 2093 for (i = start; i < limit; i++) { 2094 if (sb->d[i] == SWAPBLK_NONE) 2095 continue; 2096 if (dstobject == NULL || 2097 !swp_pager_xfer_source(srcobject, dstobject, 2098 sb->p + i - offset, sb->d[i])) { 2099 swp_pager_update_freerange(&s_free, &n_free, 2100 sb->d[i]); 2101 } 2102 sb->d[i] = SWAPBLK_NONE; 2103 } 2104 pindex = sb->p + SWAP_META_PAGES; 2105 if (swp_pager_swblk_empty(sb, 0, start) && 2106 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2107 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2108 sb->p); 2109 uma_zfree(swblk_zone, sb); 2110 } 2111 } 2112 swp_pager_freeswapspace(s_free, n_free); 2113 } 2114 2115 /* 2116 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2117 * 2118 * The requested range of blocks is freed, with any associated swap 2119 * returned to the swap bitmap. 2120 * 2121 * This routine will free swap metadata structures as they are cleaned 2122 * out. This routine does *NOT* operate on swap metadata associated 2123 * with resident pages. 2124 */ 2125 static void 2126 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2127 { 2128 swp_pager_meta_transfer(object, NULL, pindex, count); 2129 } 2130 2131 /* 2132 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2133 * 2134 * This routine locates and destroys all swap metadata associated with 2135 * an object. 2136 */ 2137 static void 2138 swp_pager_meta_free_all(vm_object_t object) 2139 { 2140 struct swblk *sb; 2141 daddr_t n_free, s_free; 2142 vm_pindex_t pindex; 2143 int i; 2144 2145 VM_OBJECT_ASSERT_WLOCKED(object); 2146 if (object->type != OBJT_SWAP) 2147 return; 2148 2149 swp_pager_init_freerange(&s_free, &n_free); 2150 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2151 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2152 pindex = sb->p + SWAP_META_PAGES; 2153 for (i = 0; i < SWAP_META_PAGES; i++) { 2154 if (sb->d[i] == SWAPBLK_NONE) 2155 continue; 2156 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2157 } 2158 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2159 uma_zfree(swblk_zone, sb); 2160 } 2161 swp_pager_freeswapspace(s_free, n_free); 2162 } 2163 2164 /* 2165 * SWP_PAGER_METACTL() - misc control of swap meta data. 2166 * 2167 * This routine is capable of looking up, or removing swapblk 2168 * assignments in the swap meta data. It returns the swapblk being 2169 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2170 * 2171 * When acting on a busy resident page and paging is in progress, we 2172 * have to wait until paging is complete but otherwise can act on the 2173 * busy page. 2174 */ 2175 static daddr_t 2176 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2177 { 2178 struct swblk *sb; 2179 2180 VM_OBJECT_ASSERT_LOCKED(object); 2181 2182 /* 2183 * The meta data only exists if the object is OBJT_SWAP 2184 * and even then might not be allocated yet. 2185 */ 2186 KASSERT(object->type == OBJT_SWAP, 2187 ("Lookup object not swappable")); 2188 2189 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2190 rounddown(pindex, SWAP_META_PAGES)); 2191 if (sb == NULL) 2192 return (SWAPBLK_NONE); 2193 return (sb->d[pindex % SWAP_META_PAGES]); 2194 } 2195 2196 /* 2197 * Returns the least page index which is greater than or equal to the 2198 * parameter pindex and for which there is a swap block allocated. 2199 * Returns object's size if the object's type is not swap or if there 2200 * are no allocated swap blocks for the object after the requested 2201 * pindex. 2202 */ 2203 vm_pindex_t 2204 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2205 { 2206 struct swblk *sb; 2207 int i; 2208 2209 VM_OBJECT_ASSERT_LOCKED(object); 2210 if (object->type != OBJT_SWAP) 2211 return (object->size); 2212 2213 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2214 rounddown(pindex, SWAP_META_PAGES)); 2215 if (sb == NULL) 2216 return (object->size); 2217 if (sb->p < pindex) { 2218 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2219 if (sb->d[i] != SWAPBLK_NONE) 2220 return (sb->p + i); 2221 } 2222 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2223 roundup(pindex, SWAP_META_PAGES)); 2224 if (sb == NULL) 2225 return (object->size); 2226 } 2227 for (i = 0; i < SWAP_META_PAGES; i++) { 2228 if (sb->d[i] != SWAPBLK_NONE) 2229 return (sb->p + i); 2230 } 2231 2232 /* 2233 * We get here if a swblk is present in the trie but it 2234 * doesn't map any blocks. 2235 */ 2236 MPASS(0); 2237 return (object->size); 2238 } 2239 2240 /* 2241 * System call swapon(name) enables swapping on device name, 2242 * which must be in the swdevsw. Return EBUSY 2243 * if already swapping on this device. 2244 */ 2245 #ifndef _SYS_SYSPROTO_H_ 2246 struct swapon_args { 2247 char *name; 2248 }; 2249 #endif 2250 2251 /* 2252 * MPSAFE 2253 */ 2254 /* ARGSUSED */ 2255 int 2256 sys_swapon(struct thread *td, struct swapon_args *uap) 2257 { 2258 struct vattr attr; 2259 struct vnode *vp; 2260 struct nameidata nd; 2261 int error; 2262 2263 error = priv_check(td, PRIV_SWAPON); 2264 if (error) 2265 return (error); 2266 2267 sx_xlock(&swdev_syscall_lock); 2268 2269 /* 2270 * Swap metadata may not fit in the KVM if we have physical 2271 * memory of >1GB. 2272 */ 2273 if (swblk_zone == NULL) { 2274 error = ENOMEM; 2275 goto done; 2276 } 2277 2278 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2279 uap->name, td); 2280 error = namei(&nd); 2281 if (error) 2282 goto done; 2283 2284 NDFREE(&nd, NDF_ONLY_PNBUF); 2285 vp = nd.ni_vp; 2286 2287 if (vn_isdisk(vp, &error)) { 2288 error = swapongeom(vp); 2289 } else if (vp->v_type == VREG && 2290 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2291 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2292 /* 2293 * Allow direct swapping to NFS regular files in the same 2294 * way that nfs_mountroot() sets up diskless swapping. 2295 */ 2296 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2297 } 2298 2299 if (error) 2300 vrele(vp); 2301 done: 2302 sx_xunlock(&swdev_syscall_lock); 2303 return (error); 2304 } 2305 2306 /* 2307 * Check that the total amount of swap currently configured does not 2308 * exceed half the theoretical maximum. If it does, print a warning 2309 * message. 2310 */ 2311 static void 2312 swapon_check_swzone(void) 2313 { 2314 2315 /* recommend using no more than half that amount */ 2316 if (swap_total > swap_maxpages / 2) { 2317 printf("warning: total configured swap (%lu pages) " 2318 "exceeds maximum recommended amount (%lu pages).\n", 2319 swap_total, swap_maxpages / 2); 2320 printf("warning: increase kern.maxswzone " 2321 "or reduce amount of swap.\n"); 2322 } 2323 } 2324 2325 static void 2326 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2327 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2328 { 2329 struct swdevt *sp, *tsp; 2330 daddr_t dvbase; 2331 u_long mblocks; 2332 2333 /* 2334 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2335 * First chop nblks off to page-align it, then convert. 2336 * 2337 * sw->sw_nblks is in page-sized chunks now too. 2338 */ 2339 nblks &= ~(ctodb(1) - 1); 2340 nblks = dbtoc(nblks); 2341 2342 /* 2343 * If we go beyond this, we get overflows in the radix 2344 * tree bitmap code. 2345 */ 2346 mblocks = 0x40000000 / BLIST_META_RADIX; 2347 if (nblks > mblocks) { 2348 printf( 2349 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2350 mblocks / 1024 / 1024 * PAGE_SIZE); 2351 nblks = mblocks; 2352 } 2353 2354 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2355 sp->sw_vp = vp; 2356 sp->sw_id = id; 2357 sp->sw_dev = dev; 2358 sp->sw_nblks = nblks; 2359 sp->sw_used = 0; 2360 sp->sw_strategy = strategy; 2361 sp->sw_close = close; 2362 sp->sw_flags = flags; 2363 2364 sp->sw_blist = blist_create(nblks, M_WAITOK); 2365 /* 2366 * Do not free the first blocks in order to avoid overwriting 2367 * any bsd label at the front of the partition 2368 */ 2369 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2370 nblks - howmany(BBSIZE, PAGE_SIZE)); 2371 2372 dvbase = 0; 2373 mtx_lock(&sw_dev_mtx); 2374 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2375 if (tsp->sw_end >= dvbase) { 2376 /* 2377 * We put one uncovered page between the devices 2378 * in order to definitively prevent any cross-device 2379 * I/O requests 2380 */ 2381 dvbase = tsp->sw_end + 1; 2382 } 2383 } 2384 sp->sw_first = dvbase; 2385 sp->sw_end = dvbase + nblks; 2386 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2387 nswapdev++; 2388 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2389 swap_total += nblks; 2390 swapon_check_swzone(); 2391 swp_sizecheck(); 2392 mtx_unlock(&sw_dev_mtx); 2393 EVENTHANDLER_INVOKE(swapon, sp); 2394 } 2395 2396 /* 2397 * SYSCALL: swapoff(devname) 2398 * 2399 * Disable swapping on the given device. 2400 * 2401 * XXX: Badly designed system call: it should use a device index 2402 * rather than filename as specification. We keep sw_vp around 2403 * only to make this work. 2404 */ 2405 #ifndef _SYS_SYSPROTO_H_ 2406 struct swapoff_args { 2407 char *name; 2408 }; 2409 #endif 2410 2411 /* 2412 * MPSAFE 2413 */ 2414 /* ARGSUSED */ 2415 int 2416 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2417 { 2418 struct vnode *vp; 2419 struct nameidata nd; 2420 struct swdevt *sp; 2421 int error; 2422 2423 error = priv_check(td, PRIV_SWAPOFF); 2424 if (error) 2425 return (error); 2426 2427 sx_xlock(&swdev_syscall_lock); 2428 2429 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2430 td); 2431 error = namei(&nd); 2432 if (error) 2433 goto done; 2434 NDFREE(&nd, NDF_ONLY_PNBUF); 2435 vp = nd.ni_vp; 2436 2437 mtx_lock(&sw_dev_mtx); 2438 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2439 if (sp->sw_vp == vp) 2440 break; 2441 } 2442 mtx_unlock(&sw_dev_mtx); 2443 if (sp == NULL) { 2444 error = EINVAL; 2445 goto done; 2446 } 2447 error = swapoff_one(sp, td->td_ucred); 2448 done: 2449 sx_xunlock(&swdev_syscall_lock); 2450 return (error); 2451 } 2452 2453 static int 2454 swapoff_one(struct swdevt *sp, struct ucred *cred) 2455 { 2456 u_long nblks; 2457 #ifdef MAC 2458 int error; 2459 #endif 2460 2461 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2462 #ifdef MAC 2463 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2464 error = mac_system_check_swapoff(cred, sp->sw_vp); 2465 (void) VOP_UNLOCK(sp->sw_vp); 2466 if (error != 0) 2467 return (error); 2468 #endif 2469 nblks = sp->sw_nblks; 2470 2471 /* 2472 * We can turn off this swap device safely only if the 2473 * available virtual memory in the system will fit the amount 2474 * of data we will have to page back in, plus an epsilon so 2475 * the system doesn't become critically low on swap space. 2476 */ 2477 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2478 return (ENOMEM); 2479 2480 /* 2481 * Prevent further allocations on this device. 2482 */ 2483 mtx_lock(&sw_dev_mtx); 2484 sp->sw_flags |= SW_CLOSING; 2485 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2486 swap_total -= nblks; 2487 mtx_unlock(&sw_dev_mtx); 2488 2489 /* 2490 * Page in the contents of the device and close it. 2491 */ 2492 swap_pager_swapoff(sp); 2493 2494 sp->sw_close(curthread, sp); 2495 mtx_lock(&sw_dev_mtx); 2496 sp->sw_id = NULL; 2497 TAILQ_REMOVE(&swtailq, sp, sw_list); 2498 nswapdev--; 2499 if (nswapdev == 0) { 2500 swap_pager_full = 2; 2501 swap_pager_almost_full = 1; 2502 } 2503 if (swdevhd == sp) 2504 swdevhd = NULL; 2505 mtx_unlock(&sw_dev_mtx); 2506 blist_destroy(sp->sw_blist); 2507 free(sp, M_VMPGDATA); 2508 return (0); 2509 } 2510 2511 void 2512 swapoff_all(void) 2513 { 2514 struct swdevt *sp, *spt; 2515 const char *devname; 2516 int error; 2517 2518 sx_xlock(&swdev_syscall_lock); 2519 2520 mtx_lock(&sw_dev_mtx); 2521 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2522 mtx_unlock(&sw_dev_mtx); 2523 if (vn_isdisk(sp->sw_vp, NULL)) 2524 devname = devtoname(sp->sw_vp->v_rdev); 2525 else 2526 devname = "[file]"; 2527 error = swapoff_one(sp, thread0.td_ucred); 2528 if (error != 0) { 2529 printf("Cannot remove swap device %s (error=%d), " 2530 "skipping.\n", devname, error); 2531 } else if (bootverbose) { 2532 printf("Swap device %s removed.\n", devname); 2533 } 2534 mtx_lock(&sw_dev_mtx); 2535 } 2536 mtx_unlock(&sw_dev_mtx); 2537 2538 sx_xunlock(&swdev_syscall_lock); 2539 } 2540 2541 void 2542 swap_pager_status(int *total, int *used) 2543 { 2544 2545 *total = swap_total; 2546 *used = swap_total - swap_pager_avail - 2547 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2548 } 2549 2550 int 2551 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2552 { 2553 struct swdevt *sp; 2554 const char *tmp_devname; 2555 int error, n; 2556 2557 n = 0; 2558 error = ENOENT; 2559 mtx_lock(&sw_dev_mtx); 2560 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2561 if (n != name) { 2562 n++; 2563 continue; 2564 } 2565 xs->xsw_version = XSWDEV_VERSION; 2566 xs->xsw_dev = sp->sw_dev; 2567 xs->xsw_flags = sp->sw_flags; 2568 xs->xsw_nblks = sp->sw_nblks; 2569 xs->xsw_used = sp->sw_used; 2570 if (devname != NULL) { 2571 if (vn_isdisk(sp->sw_vp, NULL)) 2572 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2573 else 2574 tmp_devname = "[file]"; 2575 strncpy(devname, tmp_devname, len); 2576 } 2577 error = 0; 2578 break; 2579 } 2580 mtx_unlock(&sw_dev_mtx); 2581 return (error); 2582 } 2583 2584 #if defined(COMPAT_FREEBSD11) 2585 #define XSWDEV_VERSION_11 1 2586 struct xswdev11 { 2587 u_int xsw_version; 2588 uint32_t xsw_dev; 2589 int xsw_flags; 2590 int xsw_nblks; 2591 int xsw_used; 2592 }; 2593 #endif 2594 2595 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2596 struct xswdev32 { 2597 u_int xsw_version; 2598 u_int xsw_dev1, xsw_dev2; 2599 int xsw_flags; 2600 int xsw_nblks; 2601 int xsw_used; 2602 }; 2603 #endif 2604 2605 static int 2606 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2607 { 2608 struct xswdev xs; 2609 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2610 struct xswdev32 xs32; 2611 #endif 2612 #if defined(COMPAT_FREEBSD11) 2613 struct xswdev11 xs11; 2614 #endif 2615 int error; 2616 2617 if (arg2 != 1) /* name length */ 2618 return (EINVAL); 2619 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2620 if (error != 0) 2621 return (error); 2622 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2623 if (req->oldlen == sizeof(xs32)) { 2624 xs32.xsw_version = XSWDEV_VERSION; 2625 xs32.xsw_dev1 = xs.xsw_dev; 2626 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2627 xs32.xsw_flags = xs.xsw_flags; 2628 xs32.xsw_nblks = xs.xsw_nblks; 2629 xs32.xsw_used = xs.xsw_used; 2630 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2631 return (error); 2632 } 2633 #endif 2634 #if defined(COMPAT_FREEBSD11) 2635 if (req->oldlen == sizeof(xs11)) { 2636 xs11.xsw_version = XSWDEV_VERSION_11; 2637 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2638 xs11.xsw_flags = xs.xsw_flags; 2639 xs11.xsw_nblks = xs.xsw_nblks; 2640 xs11.xsw_used = xs.xsw_used; 2641 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2642 return (error); 2643 } 2644 #endif 2645 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2646 return (error); 2647 } 2648 2649 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2650 "Number of swap devices"); 2651 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2652 sysctl_vm_swap_info, 2653 "Swap statistics by device"); 2654 2655 /* 2656 * Count the approximate swap usage in pages for a vmspace. The 2657 * shadowed or not yet copied on write swap blocks are not accounted. 2658 * The map must be locked. 2659 */ 2660 long 2661 vmspace_swap_count(struct vmspace *vmspace) 2662 { 2663 vm_map_t map; 2664 vm_map_entry_t cur; 2665 vm_object_t object; 2666 struct swblk *sb; 2667 vm_pindex_t e, pi; 2668 long count; 2669 int i; 2670 2671 map = &vmspace->vm_map; 2672 count = 0; 2673 2674 VM_MAP_ENTRY_FOREACH(cur, map) { 2675 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2676 continue; 2677 object = cur->object.vm_object; 2678 if (object == NULL || object->type != OBJT_SWAP) 2679 continue; 2680 VM_OBJECT_RLOCK(object); 2681 if (object->type != OBJT_SWAP) 2682 goto unlock; 2683 pi = OFF_TO_IDX(cur->offset); 2684 e = pi + OFF_TO_IDX(cur->end - cur->start); 2685 for (;; pi = sb->p + SWAP_META_PAGES) { 2686 sb = SWAP_PCTRIE_LOOKUP_GE( 2687 &object->un_pager.swp.swp_blks, pi); 2688 if (sb == NULL || sb->p >= e) 2689 break; 2690 for (i = 0; i < SWAP_META_PAGES; i++) { 2691 if (sb->p + i < e && 2692 sb->d[i] != SWAPBLK_NONE) 2693 count++; 2694 } 2695 } 2696 unlock: 2697 VM_OBJECT_RUNLOCK(object); 2698 } 2699 return (count); 2700 } 2701 2702 /* 2703 * GEOM backend 2704 * 2705 * Swapping onto disk devices. 2706 * 2707 */ 2708 2709 static g_orphan_t swapgeom_orphan; 2710 2711 static struct g_class g_swap_class = { 2712 .name = "SWAP", 2713 .version = G_VERSION, 2714 .orphan = swapgeom_orphan, 2715 }; 2716 2717 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2718 2719 2720 static void 2721 swapgeom_close_ev(void *arg, int flags) 2722 { 2723 struct g_consumer *cp; 2724 2725 cp = arg; 2726 g_access(cp, -1, -1, 0); 2727 g_detach(cp); 2728 g_destroy_consumer(cp); 2729 } 2730 2731 /* 2732 * Add a reference to the g_consumer for an inflight transaction. 2733 */ 2734 static void 2735 swapgeom_acquire(struct g_consumer *cp) 2736 { 2737 2738 mtx_assert(&sw_dev_mtx, MA_OWNED); 2739 cp->index++; 2740 } 2741 2742 /* 2743 * Remove a reference from the g_consumer. Post a close event if all 2744 * references go away, since the function might be called from the 2745 * biodone context. 2746 */ 2747 static void 2748 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2749 { 2750 2751 mtx_assert(&sw_dev_mtx, MA_OWNED); 2752 cp->index--; 2753 if (cp->index == 0) { 2754 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2755 sp->sw_id = NULL; 2756 } 2757 } 2758 2759 static void 2760 swapgeom_done(struct bio *bp2) 2761 { 2762 struct swdevt *sp; 2763 struct buf *bp; 2764 struct g_consumer *cp; 2765 2766 bp = bp2->bio_caller2; 2767 cp = bp2->bio_from; 2768 bp->b_ioflags = bp2->bio_flags; 2769 if (bp2->bio_error) 2770 bp->b_ioflags |= BIO_ERROR; 2771 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2772 bp->b_error = bp2->bio_error; 2773 bp->b_caller1 = NULL; 2774 bufdone(bp); 2775 sp = bp2->bio_caller1; 2776 mtx_lock(&sw_dev_mtx); 2777 swapgeom_release(cp, sp); 2778 mtx_unlock(&sw_dev_mtx); 2779 g_destroy_bio(bp2); 2780 } 2781 2782 static void 2783 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2784 { 2785 struct bio *bio; 2786 struct g_consumer *cp; 2787 2788 mtx_lock(&sw_dev_mtx); 2789 cp = sp->sw_id; 2790 if (cp == NULL) { 2791 mtx_unlock(&sw_dev_mtx); 2792 bp->b_error = ENXIO; 2793 bp->b_ioflags |= BIO_ERROR; 2794 bufdone(bp); 2795 return; 2796 } 2797 swapgeom_acquire(cp); 2798 mtx_unlock(&sw_dev_mtx); 2799 if (bp->b_iocmd == BIO_WRITE) 2800 bio = g_new_bio(); 2801 else 2802 bio = g_alloc_bio(); 2803 if (bio == NULL) { 2804 mtx_lock(&sw_dev_mtx); 2805 swapgeom_release(cp, sp); 2806 mtx_unlock(&sw_dev_mtx); 2807 bp->b_error = ENOMEM; 2808 bp->b_ioflags |= BIO_ERROR; 2809 printf("swap_pager: cannot allocate bio\n"); 2810 bufdone(bp); 2811 return; 2812 } 2813 2814 bp->b_caller1 = bio; 2815 bio->bio_caller1 = sp; 2816 bio->bio_caller2 = bp; 2817 bio->bio_cmd = bp->b_iocmd; 2818 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2819 bio->bio_length = bp->b_bcount; 2820 bio->bio_done = swapgeom_done; 2821 if (!buf_mapped(bp)) { 2822 bio->bio_ma = bp->b_pages; 2823 bio->bio_data = unmapped_buf; 2824 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2825 bio->bio_ma_n = bp->b_npages; 2826 bio->bio_flags |= BIO_UNMAPPED; 2827 } else { 2828 bio->bio_data = bp->b_data; 2829 bio->bio_ma = NULL; 2830 } 2831 g_io_request(bio, cp); 2832 return; 2833 } 2834 2835 static void 2836 swapgeom_orphan(struct g_consumer *cp) 2837 { 2838 struct swdevt *sp; 2839 int destroy; 2840 2841 mtx_lock(&sw_dev_mtx); 2842 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2843 if (sp->sw_id == cp) { 2844 sp->sw_flags |= SW_CLOSING; 2845 break; 2846 } 2847 } 2848 /* 2849 * Drop reference we were created with. Do directly since we're in a 2850 * special context where we don't have to queue the call to 2851 * swapgeom_close_ev(). 2852 */ 2853 cp->index--; 2854 destroy = ((sp != NULL) && (cp->index == 0)); 2855 if (destroy) 2856 sp->sw_id = NULL; 2857 mtx_unlock(&sw_dev_mtx); 2858 if (destroy) 2859 swapgeom_close_ev(cp, 0); 2860 } 2861 2862 static void 2863 swapgeom_close(struct thread *td, struct swdevt *sw) 2864 { 2865 struct g_consumer *cp; 2866 2867 mtx_lock(&sw_dev_mtx); 2868 cp = sw->sw_id; 2869 sw->sw_id = NULL; 2870 mtx_unlock(&sw_dev_mtx); 2871 2872 /* 2873 * swapgeom_close() may be called from the biodone context, 2874 * where we cannot perform topology changes. Delegate the 2875 * work to the events thread. 2876 */ 2877 if (cp != NULL) 2878 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2879 } 2880 2881 static int 2882 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2883 { 2884 struct g_provider *pp; 2885 struct g_consumer *cp; 2886 static struct g_geom *gp; 2887 struct swdevt *sp; 2888 u_long nblks; 2889 int error; 2890 2891 pp = g_dev_getprovider(dev); 2892 if (pp == NULL) 2893 return (ENODEV); 2894 mtx_lock(&sw_dev_mtx); 2895 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2896 cp = sp->sw_id; 2897 if (cp != NULL && cp->provider == pp) { 2898 mtx_unlock(&sw_dev_mtx); 2899 return (EBUSY); 2900 } 2901 } 2902 mtx_unlock(&sw_dev_mtx); 2903 if (gp == NULL) 2904 gp = g_new_geomf(&g_swap_class, "swap"); 2905 cp = g_new_consumer(gp); 2906 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2907 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2908 g_attach(cp, pp); 2909 /* 2910 * XXX: Every time you think you can improve the margin for 2911 * footshooting, somebody depends on the ability to do so: 2912 * savecore(8) wants to write to our swapdev so we cannot 2913 * set an exclusive count :-( 2914 */ 2915 error = g_access(cp, 1, 1, 0); 2916 if (error != 0) { 2917 g_detach(cp); 2918 g_destroy_consumer(cp); 2919 return (error); 2920 } 2921 nblks = pp->mediasize / DEV_BSIZE; 2922 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2923 swapgeom_close, dev2udev(dev), 2924 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2925 return (0); 2926 } 2927 2928 static int 2929 swapongeom(struct vnode *vp) 2930 { 2931 int error; 2932 2933 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2934 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 2935 error = ENOENT; 2936 } else { 2937 g_topology_lock(); 2938 error = swapongeom_locked(vp->v_rdev, vp); 2939 g_topology_unlock(); 2940 } 2941 VOP_UNLOCK(vp); 2942 return (error); 2943 } 2944 2945 /* 2946 * VNODE backend 2947 * 2948 * This is used mainly for network filesystem (read: probably only tested 2949 * with NFS) swapfiles. 2950 * 2951 */ 2952 2953 static void 2954 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2955 { 2956 struct vnode *vp2; 2957 2958 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2959 2960 vp2 = sp->sw_id; 2961 vhold(vp2); 2962 if (bp->b_iocmd == BIO_WRITE) { 2963 if (bp->b_bufobj) 2964 bufobj_wdrop(bp->b_bufobj); 2965 bufobj_wref(&vp2->v_bufobj); 2966 } 2967 if (bp->b_bufobj != &vp2->v_bufobj) 2968 bp->b_bufobj = &vp2->v_bufobj; 2969 bp->b_vp = vp2; 2970 bp->b_iooffset = dbtob(bp->b_blkno); 2971 bstrategy(bp); 2972 return; 2973 } 2974 2975 static void 2976 swapdev_close(struct thread *td, struct swdevt *sp) 2977 { 2978 2979 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2980 vrele(sp->sw_vp); 2981 } 2982 2983 2984 static int 2985 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2986 { 2987 struct swdevt *sp; 2988 int error; 2989 2990 if (nblks == 0) 2991 return (ENXIO); 2992 mtx_lock(&sw_dev_mtx); 2993 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2994 if (sp->sw_id == vp) { 2995 mtx_unlock(&sw_dev_mtx); 2996 return (EBUSY); 2997 } 2998 } 2999 mtx_unlock(&sw_dev_mtx); 3000 3001 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3002 #ifdef MAC 3003 error = mac_system_check_swapon(td->td_ucred, vp); 3004 if (error == 0) 3005 #endif 3006 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3007 (void) VOP_UNLOCK(vp); 3008 if (error) 3009 return (error); 3010 3011 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3012 NODEV, 0); 3013 return (0); 3014 } 3015 3016 static int 3017 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3018 { 3019 int error, new, n; 3020 3021 new = nsw_wcount_async_max; 3022 error = sysctl_handle_int(oidp, &new, 0, req); 3023 if (error != 0 || req->newptr == NULL) 3024 return (error); 3025 3026 if (new > nswbuf / 2 || new < 1) 3027 return (EINVAL); 3028 3029 mtx_lock(&swbuf_mtx); 3030 while (nsw_wcount_async_max != new) { 3031 /* 3032 * Adjust difference. If the current async count is too low, 3033 * we will need to sqeeze our update slowly in. Sleep with a 3034 * higher priority than getpbuf() to finish faster. 3035 */ 3036 n = new - nsw_wcount_async_max; 3037 if (nsw_wcount_async + n >= 0) { 3038 nsw_wcount_async += n; 3039 nsw_wcount_async_max += n; 3040 wakeup(&nsw_wcount_async); 3041 } else { 3042 nsw_wcount_async_max -= nsw_wcount_async; 3043 nsw_wcount_async = 0; 3044 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3045 "swpsysctl", 0); 3046 } 3047 } 3048 mtx_unlock(&swbuf_mtx); 3049 3050 return (0); 3051 } 3052 3053 static void 3054 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3055 vm_offset_t end) 3056 { 3057 3058 VM_OBJECT_WLOCK(object); 3059 KASSERT((object->flags & OBJ_ANON) == 0, 3060 ("Splittable object with writecount")); 3061 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3062 VM_OBJECT_WUNLOCK(object); 3063 } 3064 3065 static void 3066 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3067 vm_offset_t end) 3068 { 3069 3070 VM_OBJECT_WLOCK(object); 3071 KASSERT((object->flags & OBJ_ANON) == 0, 3072 ("Splittable object with writecount")); 3073 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3074 VM_OBJECT_WUNLOCK(object); 3075 } 3076