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 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 159 &swap_reserved, 0, sysctl_page_shift, "A", 160 "Amount of swap storage needed to back all allocated anonymous memory."); 161 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 162 &swap_total, 0, sysctl_page_shift, "A", 163 "Total amount of available swap storage."); 164 165 static int overcommit = 0; 166 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 167 "Configure virtual memory overcommit behavior. See tuning(7) " 168 "for details."); 169 static unsigned long swzone; 170 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 171 "Actual size of swap metadata zone"); 172 static unsigned long swap_maxpages; 173 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 174 "Maximum amount of swap supported"); 175 176 /* bits from overcommit */ 177 #define SWAP_RESERVE_FORCE_ON (1 << 0) 178 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 179 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 180 181 static int 182 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 183 { 184 uint64_t newval; 185 u_long value = *(u_long *)arg1; 186 187 newval = ((uint64_t)value) << PAGE_SHIFT; 188 return (sysctl_handle_64(oidp, &newval, 0, req)); 189 } 190 191 int 192 swap_reserve(vm_ooffset_t incr) 193 { 194 195 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 196 } 197 198 int 199 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 200 { 201 u_long r, s, prev, pincr; 202 int res, error; 203 static int curfail; 204 static struct timeval lastfail; 205 struct uidinfo *uip; 206 207 uip = cred->cr_ruidinfo; 208 209 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 210 (uintmax_t)incr)); 211 212 #ifdef RACCT 213 if (racct_enable) { 214 PROC_LOCK(curproc); 215 error = racct_add(curproc, RACCT_SWAP, incr); 216 PROC_UNLOCK(curproc); 217 if (error != 0) 218 return (0); 219 } 220 #endif 221 222 pincr = atop(incr); 223 res = 0; 224 prev = atomic_fetchadd_long(&swap_reserved, pincr); 225 r = prev + pincr; 226 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 227 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 228 vm_wire_count(); 229 } else 230 s = 0; 231 s += swap_total; 232 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 233 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 234 res = 1; 235 } else { 236 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 237 if (prev < pincr) 238 panic("swap_reserved < incr on overcommit fail"); 239 } 240 if (res) { 241 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 242 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 243 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 244 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 245 res = 0; 246 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 247 if (prev < pincr) 248 panic("uip->ui_vmsize < incr on overcommit fail"); 249 } 250 } 251 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 252 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 253 uip->ui_uid, curproc->p_pid, incr); 254 } 255 256 #ifdef RACCT 257 if (racct_enable && !res) { 258 PROC_LOCK(curproc); 259 racct_sub(curproc, RACCT_SWAP, incr); 260 PROC_UNLOCK(curproc); 261 } 262 #endif 263 264 return (res); 265 } 266 267 void 268 swap_reserve_force(vm_ooffset_t incr) 269 { 270 struct uidinfo *uip; 271 u_long pincr; 272 273 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 274 (uintmax_t)incr)); 275 276 PROC_LOCK(curproc); 277 #ifdef RACCT 278 if (racct_enable) 279 racct_add_force(curproc, RACCT_SWAP, incr); 280 #endif 281 pincr = atop(incr); 282 atomic_add_long(&swap_reserved, pincr); 283 uip = curproc->p_ucred->cr_ruidinfo; 284 atomic_add_long(&uip->ui_vmsize, pincr); 285 PROC_UNLOCK(curproc); 286 } 287 288 void 289 swap_release(vm_ooffset_t decr) 290 { 291 struct ucred *cred; 292 293 PROC_LOCK(curproc); 294 cred = curproc->p_ucred; 295 swap_release_by_cred(decr, cred); 296 PROC_UNLOCK(curproc); 297 } 298 299 void 300 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 301 { 302 u_long prev, pdecr; 303 struct uidinfo *uip; 304 305 uip = cred->cr_ruidinfo; 306 307 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 308 (uintmax_t)decr)); 309 310 pdecr = atop(decr); 311 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 312 if (prev < pdecr) 313 panic("swap_reserved < decr"); 314 315 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 316 if (prev < pdecr) 317 printf("negative vmsize for uid = %d\n", uip->ui_uid); 318 #ifdef RACCT 319 if (racct_enable) 320 racct_sub_cred(cred, RACCT_SWAP, decr); 321 #endif 322 } 323 324 #define SWM_POP 0x01 /* pop out */ 325 326 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 327 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 328 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 329 static int nsw_wcount_async; /* limit async write buffers */ 330 static int nsw_wcount_async_max;/* assigned maximum */ 331 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 332 333 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 334 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 335 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 336 "Maximum running async swap ops"); 337 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 338 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 339 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 340 "Swap Fragmentation Info"); 341 342 static struct sx sw_alloc_sx; 343 344 /* 345 * "named" and "unnamed" anon region objects. Try to reduce the overhead 346 * of searching a named list by hashing it just a little. 347 */ 348 349 #define NOBJLISTS 8 350 351 #define NOBJLIST(handle) \ 352 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 353 354 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 355 static uma_zone_t swwbuf_zone; 356 static uma_zone_t swrbuf_zone; 357 static uma_zone_t swblk_zone; 358 static uma_zone_t swpctrie_zone; 359 360 /* 361 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 362 * calls hooked from other parts of the VM system and do not appear here. 363 * (see vm/swap_pager.h). 364 */ 365 static vm_object_t 366 swap_pager_alloc(void *handle, vm_ooffset_t size, 367 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 368 static void swap_pager_dealloc(vm_object_t object); 369 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 370 int *); 371 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 372 int *, pgo_getpages_iodone_t, void *); 373 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 374 static boolean_t 375 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 376 static void swap_pager_init(void); 377 static void swap_pager_unswapped(vm_page_t); 378 static void swap_pager_swapoff(struct swdevt *sp); 379 static void swap_pager_update_writecount(vm_object_t object, 380 vm_offset_t start, vm_offset_t end); 381 static void swap_pager_release_writecount(vm_object_t object, 382 vm_offset_t start, vm_offset_t end); 383 384 struct pagerops swappagerops = { 385 .pgo_init = swap_pager_init, /* early system initialization of pager */ 386 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 387 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 388 .pgo_getpages = swap_pager_getpages, /* pagein */ 389 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 390 .pgo_putpages = swap_pager_putpages, /* pageout */ 391 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 392 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 393 .pgo_update_writecount = swap_pager_update_writecount, 394 .pgo_release_writecount = swap_pager_release_writecount, 395 }; 396 397 /* 398 * swap_*() routines are externally accessible. swp_*() routines are 399 * internal. 400 */ 401 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 402 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 403 404 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 405 "Maximum size of a swap block in pages"); 406 407 static void swp_sizecheck(void); 408 static void swp_pager_async_iodone(struct buf *bp); 409 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 410 static int swapongeom(struct vnode *); 411 static int swaponvp(struct thread *, struct vnode *, u_long); 412 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 413 414 /* 415 * Swap bitmap functions 416 */ 417 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 418 static daddr_t swp_pager_getswapspace(int *npages, int limit); 419 420 /* 421 * Metadata functions 422 */ 423 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 424 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 425 static void swp_pager_meta_free_all(vm_object_t); 426 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 427 428 static void 429 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 430 { 431 432 *start = SWAPBLK_NONE; 433 *num = 0; 434 } 435 436 static void 437 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 438 { 439 440 if (*start + *num == addr) { 441 (*num)++; 442 } else { 443 swp_pager_freeswapspace(*start, *num); 444 *start = addr; 445 *num = 1; 446 } 447 } 448 449 static void * 450 swblk_trie_alloc(struct pctrie *ptree) 451 { 452 453 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 454 M_USE_RESERVE : 0))); 455 } 456 457 static void 458 swblk_trie_free(struct pctrie *ptree, void *node) 459 { 460 461 uma_zfree(swpctrie_zone, node); 462 } 463 464 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 465 466 /* 467 * SWP_SIZECHECK() - update swap_pager_full indication 468 * 469 * update the swap_pager_almost_full indication and warn when we are 470 * about to run out of swap space, using lowat/hiwat hysteresis. 471 * 472 * Clear swap_pager_full ( task killing ) indication when lowat is met. 473 * 474 * No restrictions on call 475 * This routine may not block. 476 */ 477 static void 478 swp_sizecheck(void) 479 { 480 481 if (swap_pager_avail < nswap_lowat) { 482 if (swap_pager_almost_full == 0) { 483 printf("swap_pager: out of swap space\n"); 484 swap_pager_almost_full = 1; 485 } 486 } else { 487 swap_pager_full = 0; 488 if (swap_pager_avail > nswap_hiwat) 489 swap_pager_almost_full = 0; 490 } 491 } 492 493 /* 494 * SWAP_PAGER_INIT() - initialize the swap pager! 495 * 496 * Expected to be started from system init. NOTE: This code is run 497 * before much else so be careful what you depend on. Most of the VM 498 * system has yet to be initialized at this point. 499 */ 500 static void 501 swap_pager_init(void) 502 { 503 /* 504 * Initialize object lists 505 */ 506 int i; 507 508 for (i = 0; i < NOBJLISTS; ++i) 509 TAILQ_INIT(&swap_pager_object_list[i]); 510 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 511 sx_init(&sw_alloc_sx, "swspsx"); 512 sx_init(&swdev_syscall_lock, "swsysc"); 513 } 514 515 /* 516 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 517 * 518 * Expected to be started from pageout process once, prior to entering 519 * its main loop. 520 */ 521 void 522 swap_pager_swap_init(void) 523 { 524 unsigned long n, n2; 525 526 /* 527 * Number of in-transit swap bp operations. Don't 528 * exhaust the pbufs completely. Make sure we 529 * initialize workable values (0 will work for hysteresis 530 * but it isn't very efficient). 531 * 532 * The nsw_cluster_max is constrained by the bp->b_pages[] 533 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 534 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 535 * constrained by the swap device interleave stripe size. 536 * 537 * Currently we hardwire nsw_wcount_async to 4. This limit is 538 * designed to prevent other I/O from having high latencies due to 539 * our pageout I/O. The value 4 works well for one or two active swap 540 * devices but is probably a little low if you have more. Even so, 541 * a higher value would probably generate only a limited improvement 542 * with three or four active swap devices since the system does not 543 * typically have to pageout at extreme bandwidths. We will want 544 * at least 2 per swap devices, and 4 is a pretty good value if you 545 * have one NFS swap device due to the command/ack latency over NFS. 546 * So it all works out pretty well. 547 */ 548 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 549 550 nsw_wcount_async = 4; 551 nsw_wcount_async_max = nsw_wcount_async; 552 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 553 554 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 555 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 556 557 /* 558 * Initialize our zone, taking the user's requested size or 559 * estimating the number we need based on the number of pages 560 * in the system. 561 */ 562 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 563 vm_cnt.v_page_count / 2; 564 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 565 pctrie_zone_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM); 566 if (swpctrie_zone == NULL) 567 panic("failed to create swap pctrie zone."); 568 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 569 NULL, NULL, _Alignof(struct swblk) - 1, UMA_ZONE_VM); 570 if (swblk_zone == NULL) 571 panic("failed to create swap blk zone."); 572 n2 = n; 573 do { 574 if (uma_zone_reserve_kva(swblk_zone, n)) 575 break; 576 /* 577 * if the allocation failed, try a zone two thirds the 578 * size of the previous attempt. 579 */ 580 n -= ((n + 2) / 3); 581 } while (n > 0); 582 583 /* 584 * Often uma_zone_reserve_kva() cannot reserve exactly the 585 * requested size. Account for the difference when 586 * calculating swap_maxpages. 587 */ 588 n = uma_zone_get_max(swblk_zone); 589 590 if (n < n2) 591 printf("Swap blk zone entries changed from %lu to %lu.\n", 592 n2, n); 593 /* absolute maximum we can handle assuming 100% efficiency */ 594 swap_maxpages = n * SWAP_META_PAGES; 595 swzone = n * sizeof(struct swblk); 596 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 597 printf("Cannot reserve swap pctrie zone, " 598 "reduce kern.maxswzone.\n"); 599 } 600 601 static vm_object_t 602 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 603 vm_ooffset_t offset) 604 { 605 vm_object_t object; 606 607 if (cred != NULL) { 608 if (!swap_reserve_by_cred(size, cred)) 609 return (NULL); 610 crhold(cred); 611 } 612 613 /* 614 * The un_pager.swp.swp_blks trie is initialized by 615 * vm_object_allocate() to ensure the correct order of 616 * visibility to other threads. 617 */ 618 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 619 PAGE_MASK + size)); 620 621 object->un_pager.swp.writemappings = 0; 622 object->handle = handle; 623 if (cred != NULL) { 624 object->cred = cred; 625 object->charge = size; 626 } 627 return (object); 628 } 629 630 /* 631 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 632 * its metadata structures. 633 * 634 * This routine is called from the mmap and fork code to create a new 635 * OBJT_SWAP object. 636 * 637 * This routine must ensure that no live duplicate is created for 638 * the named object request, which is protected against by 639 * holding the sw_alloc_sx lock in case handle != NULL. 640 */ 641 static vm_object_t 642 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 643 vm_ooffset_t offset, struct ucred *cred) 644 { 645 vm_object_t object; 646 647 if (handle != NULL) { 648 /* 649 * Reference existing named region or allocate new one. There 650 * should not be a race here against swp_pager_meta_build() 651 * as called from vm_page_remove() in regards to the lookup 652 * of the handle. 653 */ 654 sx_xlock(&sw_alloc_sx); 655 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 656 if (object == NULL) { 657 object = swap_pager_alloc_init(handle, cred, size, 658 offset); 659 if (object != NULL) { 660 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 661 object, pager_object_list); 662 } 663 } 664 sx_xunlock(&sw_alloc_sx); 665 } else { 666 object = swap_pager_alloc_init(handle, cred, size, offset); 667 } 668 return (object); 669 } 670 671 /* 672 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 673 * 674 * The swap backing for the object is destroyed. The code is 675 * designed such that we can reinstantiate it later, but this 676 * routine is typically called only when the entire object is 677 * about to be destroyed. 678 * 679 * The object must be locked. 680 */ 681 static void 682 swap_pager_dealloc(vm_object_t object) 683 { 684 685 VM_OBJECT_ASSERT_WLOCKED(object); 686 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 687 688 /* 689 * Remove from list right away so lookups will fail if we block for 690 * pageout completion. 691 */ 692 if (object->handle != NULL) { 693 VM_OBJECT_WUNLOCK(object); 694 sx_xlock(&sw_alloc_sx); 695 TAILQ_REMOVE(NOBJLIST(object->handle), object, 696 pager_object_list); 697 sx_xunlock(&sw_alloc_sx); 698 VM_OBJECT_WLOCK(object); 699 } 700 701 vm_object_pip_wait(object, "swpdea"); 702 703 /* 704 * Free all remaining metadata. We only bother to free it from 705 * the swap meta data. We do not attempt to free swapblk's still 706 * associated with vm_page_t's for this object. We do not care 707 * if paging is still in progress on some objects. 708 */ 709 swp_pager_meta_free_all(object); 710 object->handle = NULL; 711 object->type = OBJT_DEAD; 712 } 713 714 /************************************************************************ 715 * SWAP PAGER BITMAP ROUTINES * 716 ************************************************************************/ 717 718 /* 719 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 720 * 721 * Allocate swap for up to the requested number of pages, and at 722 * least a minimum number of pages. The starting swap block number 723 * (a page index) is returned or SWAPBLK_NONE if the allocation 724 * failed. 725 * 726 * Also has the side effect of advising that somebody made a mistake 727 * when they configured swap and didn't configure enough. 728 * 729 * This routine may not sleep. 730 * 731 * We allocate in round-robin fashion from the configured devices. 732 */ 733 static daddr_t 734 swp_pager_getswapspace(int *io_npages, int limit) 735 { 736 daddr_t blk; 737 struct swdevt *sp; 738 int mpages, npages; 739 740 blk = SWAPBLK_NONE; 741 mpages = *io_npages; 742 npages = imin(BLIST_MAX_ALLOC, mpages); 743 mtx_lock(&sw_dev_mtx); 744 sp = swdevhd; 745 while (!TAILQ_EMPTY(&swtailq)) { 746 if (sp == NULL) 747 sp = TAILQ_FIRST(&swtailq); 748 if ((sp->sw_flags & SW_CLOSING) == 0) 749 blk = blist_alloc(sp->sw_blist, &npages, mpages); 750 if (blk != SWAPBLK_NONE) 751 break; 752 sp = TAILQ_NEXT(sp, sw_list); 753 if (swdevhd == sp) { 754 if (npages <= limit) 755 break; 756 mpages = npages - 1; 757 npages >>= 1; 758 } 759 } 760 if (blk != SWAPBLK_NONE) { 761 *io_npages = npages; 762 blk += sp->sw_first; 763 sp->sw_used += npages; 764 swap_pager_avail -= npages; 765 swp_sizecheck(); 766 swdevhd = TAILQ_NEXT(sp, sw_list); 767 } else { 768 if (swap_pager_full != 2) { 769 printf("swp_pager_getswapspace(%d): failed\n", 770 *io_npages); 771 swap_pager_full = 2; 772 swap_pager_almost_full = 1; 773 } 774 swdevhd = NULL; 775 } 776 mtx_unlock(&sw_dev_mtx); 777 return (blk); 778 } 779 780 static bool 781 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 782 { 783 784 return (blk >= sp->sw_first && blk < sp->sw_end); 785 } 786 787 static void 788 swp_pager_strategy(struct buf *bp) 789 { 790 struct swdevt *sp; 791 792 mtx_lock(&sw_dev_mtx); 793 TAILQ_FOREACH(sp, &swtailq, sw_list) { 794 if (swp_pager_isondev(bp->b_blkno, sp)) { 795 mtx_unlock(&sw_dev_mtx); 796 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 797 unmapped_buf_allowed) { 798 bp->b_data = unmapped_buf; 799 bp->b_offset = 0; 800 } else { 801 pmap_qenter((vm_offset_t)bp->b_data, 802 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 803 } 804 sp->sw_strategy(bp, sp); 805 return; 806 } 807 } 808 panic("Swapdev not found"); 809 } 810 811 812 /* 813 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 814 * 815 * This routine returns the specified swap blocks back to the bitmap. 816 * 817 * This routine may not sleep. 818 */ 819 static void 820 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 821 { 822 struct swdevt *sp; 823 824 if (npages == 0) 825 return; 826 mtx_lock(&sw_dev_mtx); 827 TAILQ_FOREACH(sp, &swtailq, sw_list) { 828 if (swp_pager_isondev(blk, sp)) { 829 sp->sw_used -= npages; 830 /* 831 * If we are attempting to stop swapping on 832 * this device, we don't want to mark any 833 * blocks free lest they be reused. 834 */ 835 if ((sp->sw_flags & SW_CLOSING) == 0) { 836 blist_free(sp->sw_blist, blk - sp->sw_first, 837 npages); 838 swap_pager_avail += npages; 839 swp_sizecheck(); 840 } 841 mtx_unlock(&sw_dev_mtx); 842 return; 843 } 844 } 845 panic("Swapdev not found"); 846 } 847 848 /* 849 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 850 */ 851 static int 852 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 853 { 854 struct sbuf sbuf; 855 struct swdevt *sp; 856 const char *devname; 857 int error; 858 859 error = sysctl_wire_old_buffer(req, 0); 860 if (error != 0) 861 return (error); 862 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 863 mtx_lock(&sw_dev_mtx); 864 TAILQ_FOREACH(sp, &swtailq, sw_list) { 865 if (vn_isdisk(sp->sw_vp, NULL)) 866 devname = devtoname(sp->sw_vp->v_rdev); 867 else 868 devname = "[file]"; 869 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 870 blist_stats(sp->sw_blist, &sbuf); 871 } 872 mtx_unlock(&sw_dev_mtx); 873 error = sbuf_finish(&sbuf); 874 sbuf_delete(&sbuf); 875 return (error); 876 } 877 878 /* 879 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 880 * range within an object. 881 * 882 * This is a globally accessible routine. 883 * 884 * This routine removes swapblk assignments from swap metadata. 885 * 886 * The external callers of this routine typically have already destroyed 887 * or renamed vm_page_t's associated with this range in the object so 888 * we should be ok. 889 * 890 * The object must be locked. 891 */ 892 void 893 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 894 { 895 896 swp_pager_meta_free(object, start, size); 897 } 898 899 /* 900 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 901 * 902 * Assigns swap blocks to the specified range within the object. The 903 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 904 * 905 * Returns 0 on success, -1 on failure. 906 */ 907 int 908 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 909 { 910 daddr_t addr, blk, n_free, s_free; 911 int i, j, n; 912 913 swp_pager_init_freerange(&s_free, &n_free); 914 VM_OBJECT_WLOCK(object); 915 for (i = 0; i < size; i += n) { 916 n = size - i; 917 blk = swp_pager_getswapspace(&n, 1); 918 if (blk == SWAPBLK_NONE) { 919 swp_pager_meta_free(object, start, i); 920 VM_OBJECT_WUNLOCK(object); 921 return (-1); 922 } 923 for (j = 0; j < n; ++j) { 924 addr = swp_pager_meta_build(object, 925 start + i + j, blk + j); 926 if (addr != SWAPBLK_NONE) 927 swp_pager_update_freerange(&s_free, &n_free, 928 addr); 929 } 930 } 931 swp_pager_freeswapspace(s_free, n_free); 932 VM_OBJECT_WUNLOCK(object); 933 return (0); 934 } 935 936 /* 937 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 938 * and destroy the source. 939 * 940 * Copy any valid swapblks from the source to the destination. In 941 * cases where both the source and destination have a valid swapblk, 942 * we keep the destination's. 943 * 944 * This routine is allowed to sleep. It may sleep allocating metadata 945 * indirectly through swp_pager_meta_build() or if paging is still in 946 * progress on the source. 947 * 948 * The source object contains no vm_page_t's (which is just as well) 949 * 950 * The source object is of type OBJT_SWAP. 951 * 952 * The source and destination objects must be locked. 953 * Both object locks may temporarily be released. 954 */ 955 void 956 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 957 vm_pindex_t offset, int destroysource) 958 { 959 vm_pindex_t i; 960 daddr_t dstaddr, n_free, s_free, srcaddr; 961 962 VM_OBJECT_ASSERT_WLOCKED(srcobject); 963 VM_OBJECT_ASSERT_WLOCKED(dstobject); 964 965 /* 966 * If destroysource is set, we remove the source object from the 967 * swap_pager internal queue now. 968 */ 969 if (destroysource && srcobject->handle != NULL) { 970 vm_object_pip_add(srcobject, 1); 971 VM_OBJECT_WUNLOCK(srcobject); 972 vm_object_pip_add(dstobject, 1); 973 VM_OBJECT_WUNLOCK(dstobject); 974 sx_xlock(&sw_alloc_sx); 975 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 976 pager_object_list); 977 sx_xunlock(&sw_alloc_sx); 978 VM_OBJECT_WLOCK(dstobject); 979 vm_object_pip_wakeup(dstobject); 980 VM_OBJECT_WLOCK(srcobject); 981 vm_object_pip_wakeup(srcobject); 982 } 983 984 /* 985 * Transfer source to destination. 986 */ 987 swp_pager_init_freerange(&s_free, &n_free); 988 for (i = 0; i < dstobject->size; ++i) { 989 srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP); 990 if (srcaddr == SWAPBLK_NONE) 991 continue; 992 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 993 if (dstaddr != SWAPBLK_NONE) { 994 /* 995 * Destination has valid swapblk or it is represented 996 * by a resident page. We destroy the source block. 997 */ 998 swp_pager_update_freerange(&s_free, &n_free, srcaddr); 999 continue; 1000 } 1001 1002 /* 1003 * Destination has no swapblk and is not resident, 1004 * copy source. 1005 * 1006 * swp_pager_meta_build() can sleep. 1007 */ 1008 vm_object_pip_add(srcobject, 1); 1009 VM_OBJECT_WUNLOCK(srcobject); 1010 vm_object_pip_add(dstobject, 1); 1011 dstaddr = swp_pager_meta_build(dstobject, i, srcaddr); 1012 KASSERT(dstaddr == SWAPBLK_NONE, 1013 ("Unexpected destination swapblk")); 1014 vm_object_pip_wakeup(dstobject); 1015 VM_OBJECT_WLOCK(srcobject); 1016 vm_object_pip_wakeup(srcobject); 1017 } 1018 swp_pager_freeswapspace(s_free, n_free); 1019 1020 /* 1021 * Free left over swap blocks in source. 1022 * 1023 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1024 * double-remove the object from the swap queues. 1025 */ 1026 if (destroysource) { 1027 swp_pager_meta_free_all(srcobject); 1028 /* 1029 * Reverting the type is not necessary, the caller is going 1030 * to destroy srcobject directly, but I'm doing it here 1031 * for consistency since we've removed the object from its 1032 * queues. 1033 */ 1034 srcobject->type = OBJT_DEFAULT; 1035 } 1036 } 1037 1038 /* 1039 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1040 * the requested page. 1041 * 1042 * We determine whether good backing store exists for the requested 1043 * page and return TRUE if it does, FALSE if it doesn't. 1044 * 1045 * If TRUE, we also try to determine how much valid, contiguous backing 1046 * store exists before and after the requested page. 1047 */ 1048 static boolean_t 1049 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1050 int *after) 1051 { 1052 daddr_t blk, blk0; 1053 int i; 1054 1055 VM_OBJECT_ASSERT_LOCKED(object); 1056 1057 /* 1058 * do we have good backing store at the requested index ? 1059 */ 1060 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1061 if (blk0 == SWAPBLK_NONE) { 1062 if (before) 1063 *before = 0; 1064 if (after) 1065 *after = 0; 1066 return (FALSE); 1067 } 1068 1069 /* 1070 * find backwards-looking contiguous good backing store 1071 */ 1072 if (before != NULL) { 1073 for (i = 1; i < SWB_NPAGES; i++) { 1074 if (i > pindex) 1075 break; 1076 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1077 if (blk != blk0 - i) 1078 break; 1079 } 1080 *before = i - 1; 1081 } 1082 1083 /* 1084 * find forward-looking contiguous good backing store 1085 */ 1086 if (after != NULL) { 1087 for (i = 1; i < SWB_NPAGES; i++) { 1088 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1089 if (blk != blk0 + i) 1090 break; 1091 } 1092 *after = i - 1; 1093 } 1094 return (TRUE); 1095 } 1096 1097 /* 1098 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1099 * 1100 * This removes any associated swap backing store, whether valid or 1101 * not, from the page. 1102 * 1103 * This routine is typically called when a page is made dirty, at 1104 * which point any associated swap can be freed. MADV_FREE also 1105 * calls us in a special-case situation 1106 * 1107 * NOTE!!! If the page is clean and the swap was valid, the caller 1108 * should make the page dirty before calling this routine. This routine 1109 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1110 * depends on it. 1111 * 1112 * This routine may not sleep. 1113 * 1114 * The object containing the page must be locked. 1115 */ 1116 static void 1117 swap_pager_unswapped(vm_page_t m) 1118 { 1119 daddr_t srcaddr; 1120 1121 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP); 1122 if (srcaddr != SWAPBLK_NONE) 1123 swp_pager_freeswapspace(srcaddr, 1); 1124 } 1125 1126 /* 1127 * swap_pager_getpages() - bring pages in from swap 1128 * 1129 * Attempt to page in the pages in array "ma" of length "count". The 1130 * caller may optionally specify that additional pages preceding and 1131 * succeeding the specified range be paged in. The number of such pages 1132 * is returned in the "rbehind" and "rahead" parameters, and they will 1133 * be in the inactive queue upon return. 1134 * 1135 * The pages in "ma" must be busied and will remain busied upon return. 1136 */ 1137 static int 1138 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1139 int *rahead) 1140 { 1141 struct buf *bp; 1142 vm_page_t bm, mpred, msucc, p; 1143 vm_pindex_t pindex; 1144 daddr_t blk; 1145 int i, maxahead, maxbehind, reqcount; 1146 1147 reqcount = count; 1148 1149 /* 1150 * Determine the final number of read-behind pages and 1151 * allocate them BEFORE releasing the object lock. Otherwise, 1152 * there can be a problematic race with vm_object_split(). 1153 * Specifically, vm_object_split() might first transfer pages 1154 * that precede ma[0] in the current object to a new object, 1155 * and then this function incorrectly recreates those pages as 1156 * read-behind pages in the current object. 1157 */ 1158 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1159 return (VM_PAGER_FAIL); 1160 1161 /* 1162 * Clip the readahead and readbehind ranges to exclude resident pages. 1163 */ 1164 if (rahead != NULL) { 1165 KASSERT(reqcount - 1 <= maxahead, 1166 ("page count %d extends beyond swap block", reqcount)); 1167 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1168 pindex = ma[reqcount - 1]->pindex; 1169 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1170 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1171 *rahead = msucc->pindex - pindex - 1; 1172 } 1173 if (rbehind != NULL) { 1174 *rbehind = imin(*rbehind, maxbehind); 1175 pindex = ma[0]->pindex; 1176 mpred = TAILQ_PREV(ma[0], pglist, listq); 1177 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1178 *rbehind = pindex - mpred->pindex - 1; 1179 } 1180 1181 bm = ma[0]; 1182 for (i = 0; i < count; i++) 1183 ma[i]->oflags |= VPO_SWAPINPROG; 1184 1185 /* 1186 * Allocate readahead and readbehind pages. 1187 */ 1188 if (rbehind != NULL) { 1189 for (i = 1; i <= *rbehind; i++) { 1190 p = vm_page_alloc(object, ma[0]->pindex - i, 1191 VM_ALLOC_NORMAL); 1192 if (p == NULL) 1193 break; 1194 p->oflags |= VPO_SWAPINPROG; 1195 bm = p; 1196 } 1197 *rbehind = i - 1; 1198 } 1199 if (rahead != NULL) { 1200 for (i = 0; i < *rahead; i++) { 1201 p = vm_page_alloc(object, 1202 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1203 if (p == NULL) 1204 break; 1205 p->oflags |= VPO_SWAPINPROG; 1206 } 1207 *rahead = i; 1208 } 1209 if (rbehind != NULL) 1210 count += *rbehind; 1211 if (rahead != NULL) 1212 count += *rahead; 1213 1214 vm_object_pip_add(object, count); 1215 1216 pindex = bm->pindex; 1217 blk = swp_pager_meta_ctl(object, pindex, 0); 1218 KASSERT(blk != SWAPBLK_NONE, 1219 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1220 1221 VM_OBJECT_WUNLOCK(object); 1222 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1223 /* Pages cannot leave the object while busy. */ 1224 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1225 MPASS(p->pindex == bm->pindex + i); 1226 bp->b_pages[i] = p; 1227 } 1228 1229 bp->b_flags |= B_PAGING; 1230 bp->b_iocmd = BIO_READ; 1231 bp->b_iodone = swp_pager_async_iodone; 1232 bp->b_rcred = crhold(thread0.td_ucred); 1233 bp->b_wcred = crhold(thread0.td_ucred); 1234 bp->b_blkno = blk; 1235 bp->b_bcount = PAGE_SIZE * count; 1236 bp->b_bufsize = PAGE_SIZE * count; 1237 bp->b_npages = count; 1238 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1239 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1240 1241 VM_CNT_INC(v_swapin); 1242 VM_CNT_ADD(v_swappgsin, count); 1243 1244 /* 1245 * perform the I/O. NOTE!!! bp cannot be considered valid after 1246 * this point because we automatically release it on completion. 1247 * Instead, we look at the one page we are interested in which we 1248 * still hold a lock on even through the I/O completion. 1249 * 1250 * The other pages in our ma[] array are also released on completion, 1251 * so we cannot assume they are valid anymore either. 1252 * 1253 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1254 */ 1255 BUF_KERNPROC(bp); 1256 swp_pager_strategy(bp); 1257 1258 /* 1259 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1260 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1261 * is set in the metadata for each page in the request. 1262 */ 1263 VM_OBJECT_WLOCK(object); 1264 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1265 ma[0]->oflags |= VPO_SWAPSLEEP; 1266 VM_CNT_INC(v_intrans); 1267 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1268 "swread", hz * 20)) { 1269 printf( 1270 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1271 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1272 } 1273 } 1274 1275 /* 1276 * If we had an unrecoverable read error pages will not be valid. 1277 */ 1278 for (i = 0; i < reqcount; i++) 1279 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1280 return (VM_PAGER_ERROR); 1281 1282 return (VM_PAGER_OK); 1283 1284 /* 1285 * A final note: in a low swap situation, we cannot deallocate swap 1286 * and mark a page dirty here because the caller is likely to mark 1287 * the page clean when we return, causing the page to possibly revert 1288 * to all-zero's later. 1289 */ 1290 } 1291 1292 /* 1293 * swap_pager_getpages_async(): 1294 * 1295 * Right now this is emulation of asynchronous operation on top of 1296 * swap_pager_getpages(). 1297 */ 1298 static int 1299 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1300 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1301 { 1302 int r, error; 1303 1304 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1305 VM_OBJECT_WUNLOCK(object); 1306 switch (r) { 1307 case VM_PAGER_OK: 1308 error = 0; 1309 break; 1310 case VM_PAGER_ERROR: 1311 error = EIO; 1312 break; 1313 case VM_PAGER_FAIL: 1314 error = EINVAL; 1315 break; 1316 default: 1317 panic("unhandled swap_pager_getpages() error %d", r); 1318 } 1319 (iodone)(arg, ma, count, error); 1320 VM_OBJECT_WLOCK(object); 1321 1322 return (r); 1323 } 1324 1325 /* 1326 * swap_pager_putpages: 1327 * 1328 * Assign swap (if necessary) and initiate I/O on the specified pages. 1329 * 1330 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1331 * are automatically converted to SWAP objects. 1332 * 1333 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1334 * vm_page reservation system coupled with properly written VFS devices 1335 * should ensure that no low-memory deadlock occurs. This is an area 1336 * which needs work. 1337 * 1338 * The parent has N vm_object_pip_add() references prior to 1339 * calling us and will remove references for rtvals[] that are 1340 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1341 * completion. 1342 * 1343 * The parent has soft-busy'd the pages it passes us and will unbusy 1344 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1345 * We need to unbusy the rest on I/O completion. 1346 */ 1347 static void 1348 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1349 int flags, int *rtvals) 1350 { 1351 struct buf *bp; 1352 daddr_t addr, blk, n_free, s_free; 1353 vm_page_t mreq; 1354 int i, j, n; 1355 bool async; 1356 1357 KASSERT(count == 0 || ma[0]->object == object, 1358 ("%s: object mismatch %p/%p", 1359 __func__, object, ma[0]->object)); 1360 1361 /* 1362 * Step 1 1363 * 1364 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1365 */ 1366 if (object->type != OBJT_SWAP) { 1367 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1368 KASSERT(addr == SWAPBLK_NONE, 1369 ("unexpected object swap block")); 1370 } 1371 VM_OBJECT_WUNLOCK(object); 1372 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1373 swp_pager_init_freerange(&s_free, &n_free); 1374 1375 /* 1376 * Step 2 1377 * 1378 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1379 * The page is left dirty until the pageout operation completes 1380 * successfully. 1381 */ 1382 for (i = 0; i < count; i += n) { 1383 /* Maximum I/O size is limited by maximum swap block size. */ 1384 n = min(count - i, nsw_cluster_max); 1385 1386 /* Get a block of swap of size up to size n. */ 1387 blk = swp_pager_getswapspace(&n, 4); 1388 if (blk == SWAPBLK_NONE) { 1389 for (j = 0; j < n; ++j) 1390 rtvals[i + j] = VM_PAGER_FAIL; 1391 continue; 1392 } 1393 1394 /* 1395 * All I/O parameters have been satisfied. Build the I/O 1396 * request and assign the swap space. 1397 */ 1398 if (async) { 1399 mtx_lock(&swbuf_mtx); 1400 while (nsw_wcount_async == 0) 1401 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1402 "swbufa", 0); 1403 nsw_wcount_async--; 1404 mtx_unlock(&swbuf_mtx); 1405 } 1406 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1407 if (async) 1408 bp->b_flags = B_ASYNC; 1409 bp->b_flags |= B_PAGING; 1410 bp->b_iocmd = BIO_WRITE; 1411 1412 bp->b_rcred = crhold(thread0.td_ucred); 1413 bp->b_wcred = crhold(thread0.td_ucred); 1414 bp->b_bcount = PAGE_SIZE * n; 1415 bp->b_bufsize = PAGE_SIZE * n; 1416 bp->b_blkno = blk; 1417 1418 VM_OBJECT_WLOCK(object); 1419 for (j = 0; j < n; ++j) { 1420 mreq = ma[i + j]; 1421 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1422 blk + j); 1423 if (addr != SWAPBLK_NONE) 1424 swp_pager_update_freerange(&s_free, &n_free, 1425 addr); 1426 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1427 mreq->oflags |= VPO_SWAPINPROG; 1428 bp->b_pages[j] = mreq; 1429 } 1430 VM_OBJECT_WUNLOCK(object); 1431 bp->b_npages = n; 1432 /* 1433 * Must set dirty range for NFS to work. 1434 */ 1435 bp->b_dirtyoff = 0; 1436 bp->b_dirtyend = bp->b_bcount; 1437 1438 VM_CNT_INC(v_swapout); 1439 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1440 1441 /* 1442 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1443 * can call the async completion routine at the end of a 1444 * synchronous I/O operation. Otherwise, our caller would 1445 * perform duplicate unbusy and wakeup operations on the page 1446 * and object, respectively. 1447 */ 1448 for (j = 0; j < n; j++) 1449 rtvals[i + j] = VM_PAGER_PEND; 1450 1451 /* 1452 * asynchronous 1453 * 1454 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1455 */ 1456 if (async) { 1457 bp->b_iodone = swp_pager_async_iodone; 1458 BUF_KERNPROC(bp); 1459 swp_pager_strategy(bp); 1460 continue; 1461 } 1462 1463 /* 1464 * synchronous 1465 * 1466 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1467 */ 1468 bp->b_iodone = bdone; 1469 swp_pager_strategy(bp); 1470 1471 /* 1472 * Wait for the sync I/O to complete. 1473 */ 1474 bwait(bp, PVM, "swwrt"); 1475 1476 /* 1477 * Now that we are through with the bp, we can call the 1478 * normal async completion, which frees everything up. 1479 */ 1480 swp_pager_async_iodone(bp); 1481 } 1482 swp_pager_freeswapspace(s_free, n_free); 1483 VM_OBJECT_WLOCK(object); 1484 } 1485 1486 /* 1487 * swp_pager_async_iodone: 1488 * 1489 * Completion routine for asynchronous reads and writes from/to swap. 1490 * Also called manually by synchronous code to finish up a bp. 1491 * 1492 * This routine may not sleep. 1493 */ 1494 static void 1495 swp_pager_async_iodone(struct buf *bp) 1496 { 1497 int i; 1498 vm_object_t object = NULL; 1499 1500 /* 1501 * Report error - unless we ran out of memory, in which case 1502 * we've already logged it in swapgeom_strategy(). 1503 */ 1504 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1505 printf( 1506 "swap_pager: I/O error - %s failed; blkno %ld," 1507 "size %ld, error %d\n", 1508 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1509 (long)bp->b_blkno, 1510 (long)bp->b_bcount, 1511 bp->b_error 1512 ); 1513 } 1514 1515 /* 1516 * remove the mapping for kernel virtual 1517 */ 1518 if (buf_mapped(bp)) 1519 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1520 else 1521 bp->b_data = bp->b_kvabase; 1522 1523 if (bp->b_npages) { 1524 object = bp->b_pages[0]->object; 1525 VM_OBJECT_WLOCK(object); 1526 } 1527 1528 /* 1529 * cleanup pages. If an error occurs writing to swap, we are in 1530 * very serious trouble. If it happens to be a disk error, though, 1531 * we may be able to recover by reassigning the swap later on. So 1532 * in this case we remove the m->swapblk assignment for the page 1533 * but do not free it in the rlist. The errornous block(s) are thus 1534 * never reallocated as swap. Redirty the page and continue. 1535 */ 1536 for (i = 0; i < bp->b_npages; ++i) { 1537 vm_page_t m = bp->b_pages[i]; 1538 1539 m->oflags &= ~VPO_SWAPINPROG; 1540 if (m->oflags & VPO_SWAPSLEEP) { 1541 m->oflags &= ~VPO_SWAPSLEEP; 1542 wakeup(&object->handle); 1543 } 1544 1545 if (bp->b_ioflags & BIO_ERROR) { 1546 /* 1547 * If an error occurs I'd love to throw the swapblk 1548 * away without freeing it back to swapspace, so it 1549 * can never be used again. But I can't from an 1550 * interrupt. 1551 */ 1552 if (bp->b_iocmd == BIO_READ) { 1553 /* 1554 * NOTE: for reads, m->dirty will probably 1555 * be overridden by the original caller of 1556 * getpages so don't play cute tricks here. 1557 */ 1558 vm_page_invalid(m); 1559 } else { 1560 /* 1561 * If a write error occurs, reactivate page 1562 * so it doesn't clog the inactive list, 1563 * then finish the I/O. 1564 */ 1565 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1566 vm_page_lock(m); 1567 vm_page_activate(m); 1568 vm_page_unlock(m); 1569 vm_page_sunbusy(m); 1570 } 1571 } else if (bp->b_iocmd == BIO_READ) { 1572 /* 1573 * NOTE: for reads, m->dirty will probably be 1574 * overridden by the original caller of getpages so 1575 * we cannot set them in order to free the underlying 1576 * swap in a low-swap situation. I don't think we'd 1577 * want to do that anyway, but it was an optimization 1578 * that existed in the old swapper for a time before 1579 * it got ripped out due to precisely this problem. 1580 */ 1581 KASSERT(!pmap_page_is_mapped(m), 1582 ("swp_pager_async_iodone: page %p is mapped", m)); 1583 KASSERT(m->dirty == 0, 1584 ("swp_pager_async_iodone: page %p is dirty", m)); 1585 1586 vm_page_valid(m); 1587 if (i < bp->b_pgbefore || 1588 i >= bp->b_npages - bp->b_pgafter) 1589 vm_page_readahead_finish(m); 1590 } else { 1591 /* 1592 * For write success, clear the dirty 1593 * status, then finish the I/O ( which decrements the 1594 * busy count and possibly wakes waiter's up ). 1595 * A page is only written to swap after a period of 1596 * inactivity. Therefore, we do not expect it to be 1597 * reused. 1598 */ 1599 KASSERT(!pmap_page_is_write_mapped(m), 1600 ("swp_pager_async_iodone: page %p is not write" 1601 " protected", m)); 1602 vm_page_undirty(m); 1603 vm_page_lock(m); 1604 vm_page_deactivate_noreuse(m); 1605 vm_page_unlock(m); 1606 vm_page_sunbusy(m); 1607 } 1608 } 1609 1610 /* 1611 * adjust pip. NOTE: the original parent may still have its own 1612 * pip refs on the object. 1613 */ 1614 if (object != NULL) { 1615 vm_object_pip_wakeupn(object, bp->b_npages); 1616 VM_OBJECT_WUNLOCK(object); 1617 } 1618 1619 /* 1620 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1621 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1622 * trigger a KASSERT in relpbuf(). 1623 */ 1624 if (bp->b_vp) { 1625 bp->b_vp = NULL; 1626 bp->b_bufobj = NULL; 1627 } 1628 /* 1629 * release the physical I/O buffer 1630 */ 1631 if (bp->b_flags & B_ASYNC) { 1632 mtx_lock(&swbuf_mtx); 1633 if (++nsw_wcount_async == 1) 1634 wakeup(&nsw_wcount_async); 1635 mtx_unlock(&swbuf_mtx); 1636 } 1637 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1638 } 1639 1640 int 1641 swap_pager_nswapdev(void) 1642 { 1643 1644 return (nswapdev); 1645 } 1646 1647 static void 1648 swp_pager_force_dirty(vm_page_t m) 1649 { 1650 1651 vm_page_dirty(m); 1652 #ifdef INVARIANTS 1653 vm_page_lock(m); 1654 if (!vm_page_wired(m) && m->queue == PQ_NONE) 1655 panic("page %p is neither wired nor queued", m); 1656 vm_page_unlock(m); 1657 #endif 1658 vm_page_xunbusy(m); 1659 swap_pager_unswapped(m); 1660 } 1661 1662 static void 1663 swp_pager_force_launder(vm_page_t m) 1664 { 1665 1666 vm_page_dirty(m); 1667 vm_page_lock(m); 1668 vm_page_launder(m); 1669 vm_page_unlock(m); 1670 vm_page_xunbusy(m); 1671 swap_pager_unswapped(m); 1672 } 1673 1674 /* 1675 * SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in 1676 * 1677 * This routine dissociates pages starting at the given index within an 1678 * object from their backing store, paging them in if they do not reside 1679 * in memory. Pages that are paged in are marked dirty and placed in the 1680 * laundry queue. Pages are marked dirty because they no longer have 1681 * backing store. They are placed in the laundry queue because they have 1682 * not been accessed recently. Otherwise, they would already reside in 1683 * memory. 1684 */ 1685 static void 1686 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages) 1687 { 1688 vm_page_t ma[npages]; 1689 int i, j; 1690 1691 KASSERT(npages > 0, ("%s: No pages", __func__)); 1692 KASSERT(npages <= MAXPHYS / PAGE_SIZE, 1693 ("%s: Too many pages: %d", __func__, npages)); 1694 vm_object_pip_add(object, npages); 1695 vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages); 1696 for (i = j = 0;; i++) { 1697 /* Count nonresident pages, to page-in all at once. */ 1698 if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL) 1699 continue; 1700 if (j < i) { 1701 /* Page-in nonresident pages. Mark for laundering. */ 1702 if (swap_pager_getpages(object, &ma[j], i - j, NULL, 1703 NULL) != VM_PAGER_OK) 1704 panic("%s: read from swap failed", __func__); 1705 do { 1706 swp_pager_force_launder(ma[j]); 1707 } while (++j < i); 1708 } 1709 if (i == npages) 1710 break; 1711 /* Mark dirty a resident page. */ 1712 swp_pager_force_dirty(ma[j++]); 1713 } 1714 vm_object_pip_wakeupn(object, npages); 1715 } 1716 1717 /* 1718 * swap_pager_swapoff_object: 1719 * 1720 * Page in all of the pages that have been paged out for an object 1721 * to a swap device. 1722 */ 1723 static void 1724 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1725 { 1726 struct swblk *sb; 1727 vm_pindex_t pi, s_pindex; 1728 daddr_t blk, n_blks, s_blk; 1729 int i; 1730 1731 n_blks = 0; 1732 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1733 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1734 for (i = 0; i < SWAP_META_PAGES; i++) { 1735 blk = sb->d[i]; 1736 if (!swp_pager_isondev(blk, sp)) 1737 blk = SWAPBLK_NONE; 1738 1739 /* 1740 * If there are no blocks/pages accumulated, start a new 1741 * accumulation here. 1742 */ 1743 if (n_blks == 0) { 1744 if (blk != SWAPBLK_NONE) { 1745 s_blk = blk; 1746 s_pindex = sb->p + i; 1747 n_blks = 1; 1748 } 1749 continue; 1750 } 1751 1752 /* 1753 * If the accumulation can be extended without breaking 1754 * the sequence of consecutive blocks and pages that 1755 * swp_pager_force_pagein() depends on, do so. 1756 */ 1757 if (n_blks < MAXPHYS / PAGE_SIZE && 1758 s_blk + n_blks == blk && 1759 s_pindex + n_blks == sb->p + i) { 1760 ++n_blks; 1761 continue; 1762 } 1763 1764 /* 1765 * The sequence of consecutive blocks and pages cannot 1766 * be extended, so page them all in here. Then, 1767 * because doing so involves releasing and reacquiring 1768 * a lock that protects the swap block pctrie, do not 1769 * rely on the current swap block. Break this loop and 1770 * re-fetch the same pindex from the pctrie again. 1771 */ 1772 swp_pager_force_pagein(object, s_pindex, n_blks); 1773 n_blks = 0; 1774 break; 1775 } 1776 if (i == SWAP_META_PAGES) 1777 pi = sb->p + SWAP_META_PAGES; 1778 } 1779 if (n_blks > 0) 1780 swp_pager_force_pagein(object, s_pindex, n_blks); 1781 } 1782 1783 /* 1784 * swap_pager_swapoff: 1785 * 1786 * Page in all of the pages that have been paged out to the 1787 * given device. The corresponding blocks in the bitmap must be 1788 * marked as allocated and the device must be flagged SW_CLOSING. 1789 * There may be no processes swapped out to the device. 1790 * 1791 * This routine may block. 1792 */ 1793 static void 1794 swap_pager_swapoff(struct swdevt *sp) 1795 { 1796 vm_object_t object; 1797 int retries; 1798 1799 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1800 1801 retries = 0; 1802 full_rescan: 1803 mtx_lock(&vm_object_list_mtx); 1804 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1805 if (object->type != OBJT_SWAP) 1806 continue; 1807 mtx_unlock(&vm_object_list_mtx); 1808 /* Depends on type-stability. */ 1809 VM_OBJECT_WLOCK(object); 1810 1811 /* 1812 * Dead objects are eventually terminated on their own. 1813 */ 1814 if ((object->flags & OBJ_DEAD) != 0) 1815 goto next_obj; 1816 1817 /* 1818 * Sync with fences placed after pctrie 1819 * initialization. We must not access pctrie below 1820 * unless we checked that our object is swap and not 1821 * dead. 1822 */ 1823 atomic_thread_fence_acq(); 1824 if (object->type != OBJT_SWAP) 1825 goto next_obj; 1826 1827 swap_pager_swapoff_object(sp, object); 1828 next_obj: 1829 VM_OBJECT_WUNLOCK(object); 1830 mtx_lock(&vm_object_list_mtx); 1831 } 1832 mtx_unlock(&vm_object_list_mtx); 1833 1834 if (sp->sw_used) { 1835 /* 1836 * Objects may be locked or paging to the device being 1837 * removed, so we will miss their pages and need to 1838 * make another pass. We have marked this device as 1839 * SW_CLOSING, so the activity should finish soon. 1840 */ 1841 retries++; 1842 if (retries > 100) { 1843 panic("swapoff: failed to locate %d swap blocks", 1844 sp->sw_used); 1845 } 1846 pause("swpoff", hz / 20); 1847 goto full_rescan; 1848 } 1849 EVENTHANDLER_INVOKE(swapoff, sp); 1850 } 1851 1852 /************************************************************************ 1853 * SWAP META DATA * 1854 ************************************************************************ 1855 * 1856 * These routines manipulate the swap metadata stored in the 1857 * OBJT_SWAP object. 1858 * 1859 * Swap metadata is implemented with a global hash and not directly 1860 * linked into the object. Instead the object simply contains 1861 * appropriate tracking counters. 1862 */ 1863 1864 /* 1865 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1866 */ 1867 static bool 1868 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1869 { 1870 int i; 1871 1872 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1873 for (i = start; i < limit; i++) { 1874 if (sb->d[i] != SWAPBLK_NONE) 1875 return (false); 1876 } 1877 return (true); 1878 } 1879 1880 /* 1881 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1882 * 1883 * We first convert the object to a swap object if it is a default 1884 * object. 1885 * 1886 * The specified swapblk is added to the object's swap metadata. If 1887 * the swapblk is not valid, it is freed instead. Any previously 1888 * assigned swapblk is returned. 1889 */ 1890 static daddr_t 1891 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1892 { 1893 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1894 struct swblk *sb, *sb1; 1895 vm_pindex_t modpi, rdpi; 1896 daddr_t prev_swapblk; 1897 int error, i; 1898 1899 VM_OBJECT_ASSERT_WLOCKED(object); 1900 1901 /* 1902 * Convert default object to swap object if necessary 1903 */ 1904 if (object->type != OBJT_SWAP) { 1905 pctrie_init(&object->un_pager.swp.swp_blks); 1906 1907 /* 1908 * Ensure that swap_pager_swapoff()'s iteration over 1909 * object_list does not see a garbage pctrie. 1910 */ 1911 atomic_thread_fence_rel(); 1912 1913 object->type = OBJT_SWAP; 1914 object->un_pager.swp.writemappings = 0; 1915 KASSERT(object->handle == NULL, ("default pager with handle")); 1916 } 1917 1918 rdpi = rounddown(pindex, SWAP_META_PAGES); 1919 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1920 if (sb == NULL) { 1921 if (swapblk == SWAPBLK_NONE) 1922 return (SWAPBLK_NONE); 1923 for (;;) { 1924 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1925 pageproc ? M_USE_RESERVE : 0)); 1926 if (sb != NULL) { 1927 sb->p = rdpi; 1928 for (i = 0; i < SWAP_META_PAGES; i++) 1929 sb->d[i] = SWAPBLK_NONE; 1930 if (atomic_cmpset_int(&swblk_zone_exhausted, 1931 1, 0)) 1932 printf("swblk zone ok\n"); 1933 break; 1934 } 1935 VM_OBJECT_WUNLOCK(object); 1936 if (uma_zone_exhausted(swblk_zone)) { 1937 if (atomic_cmpset_int(&swblk_zone_exhausted, 1938 0, 1)) 1939 printf("swap blk zone exhausted, " 1940 "increase kern.maxswzone\n"); 1941 vm_pageout_oom(VM_OOM_SWAPZ); 1942 pause("swzonxb", 10); 1943 } else 1944 uma_zwait(swblk_zone); 1945 VM_OBJECT_WLOCK(object); 1946 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1947 rdpi); 1948 if (sb != NULL) 1949 /* 1950 * Somebody swapped out a nearby page, 1951 * allocating swblk at the rdpi index, 1952 * while we dropped the object lock. 1953 */ 1954 goto allocated; 1955 } 1956 for (;;) { 1957 error = SWAP_PCTRIE_INSERT( 1958 &object->un_pager.swp.swp_blks, sb); 1959 if (error == 0) { 1960 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1961 1, 0)) 1962 printf("swpctrie zone ok\n"); 1963 break; 1964 } 1965 VM_OBJECT_WUNLOCK(object); 1966 if (uma_zone_exhausted(swpctrie_zone)) { 1967 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1968 0, 1)) 1969 printf("swap pctrie zone exhausted, " 1970 "increase kern.maxswzone\n"); 1971 vm_pageout_oom(VM_OOM_SWAPZ); 1972 pause("swzonxp", 10); 1973 } else 1974 uma_zwait(swpctrie_zone); 1975 VM_OBJECT_WLOCK(object); 1976 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1977 rdpi); 1978 if (sb1 != NULL) { 1979 uma_zfree(swblk_zone, sb); 1980 sb = sb1; 1981 goto allocated; 1982 } 1983 } 1984 } 1985 allocated: 1986 MPASS(sb->p == rdpi); 1987 1988 modpi = pindex % SWAP_META_PAGES; 1989 /* Return prior contents of metadata. */ 1990 prev_swapblk = sb->d[modpi]; 1991 /* Enter block into metadata. */ 1992 sb->d[modpi] = swapblk; 1993 1994 /* 1995 * Free the swblk if we end up with the empty page run. 1996 */ 1997 if (swapblk == SWAPBLK_NONE && 1998 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1999 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 2000 uma_zfree(swblk_zone, sb); 2001 } 2002 return (prev_swapblk); 2003 } 2004 2005 /* 2006 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2007 * 2008 * The requested range of blocks is freed, with any associated swap 2009 * returned to the swap bitmap. 2010 * 2011 * This routine will free swap metadata structures as they are cleaned 2012 * out. This routine does *NOT* operate on swap metadata associated 2013 * with resident pages. 2014 */ 2015 static void 2016 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2017 { 2018 struct swblk *sb; 2019 daddr_t n_free, s_free; 2020 vm_pindex_t last; 2021 int i, limit, start; 2022 2023 VM_OBJECT_ASSERT_WLOCKED(object); 2024 if (object->type != OBJT_SWAP || count == 0) 2025 return; 2026 2027 swp_pager_init_freerange(&s_free, &n_free); 2028 last = pindex + count; 2029 for (;;) { 2030 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2031 rounddown(pindex, SWAP_META_PAGES)); 2032 if (sb == NULL || sb->p >= last) 2033 break; 2034 start = pindex > sb->p ? pindex - sb->p : 0; 2035 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2036 SWAP_META_PAGES; 2037 for (i = start; i < limit; i++) { 2038 if (sb->d[i] == SWAPBLK_NONE) 2039 continue; 2040 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2041 sb->d[i] = SWAPBLK_NONE; 2042 } 2043 pindex = sb->p + SWAP_META_PAGES; 2044 if (swp_pager_swblk_empty(sb, 0, start) && 2045 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2046 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2047 sb->p); 2048 uma_zfree(swblk_zone, sb); 2049 } 2050 } 2051 swp_pager_freeswapspace(s_free, n_free); 2052 } 2053 2054 /* 2055 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2056 * 2057 * This routine locates and destroys all swap metadata associated with 2058 * an object. 2059 */ 2060 static void 2061 swp_pager_meta_free_all(vm_object_t object) 2062 { 2063 struct swblk *sb; 2064 daddr_t n_free, s_free; 2065 vm_pindex_t pindex; 2066 int i; 2067 2068 VM_OBJECT_ASSERT_WLOCKED(object); 2069 if (object->type != OBJT_SWAP) 2070 return; 2071 2072 swp_pager_init_freerange(&s_free, &n_free); 2073 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2074 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2075 pindex = sb->p + SWAP_META_PAGES; 2076 for (i = 0; i < SWAP_META_PAGES; i++) { 2077 if (sb->d[i] == SWAPBLK_NONE) 2078 continue; 2079 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2080 } 2081 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2082 uma_zfree(swblk_zone, sb); 2083 } 2084 swp_pager_freeswapspace(s_free, n_free); 2085 } 2086 2087 /* 2088 * SWP_PAGER_METACTL() - misc control of swap meta data. 2089 * 2090 * This routine is capable of looking up, or removing swapblk 2091 * assignments in the swap meta data. It returns the swapblk being 2092 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2093 * 2094 * When acting on a busy resident page and paging is in progress, we 2095 * have to wait until paging is complete but otherwise can act on the 2096 * busy page. 2097 * 2098 * SWM_POP remove from meta data but do not free it 2099 */ 2100 static daddr_t 2101 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2102 { 2103 struct swblk *sb; 2104 daddr_t r1; 2105 2106 if ((flags & SWM_POP) != 0) 2107 VM_OBJECT_ASSERT_WLOCKED(object); 2108 else 2109 VM_OBJECT_ASSERT_LOCKED(object); 2110 2111 /* 2112 * The meta data only exists if the object is OBJT_SWAP 2113 * and even then might not be allocated yet. 2114 */ 2115 if (object->type != OBJT_SWAP) 2116 return (SWAPBLK_NONE); 2117 2118 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2119 rounddown(pindex, SWAP_META_PAGES)); 2120 if (sb == NULL) 2121 return (SWAPBLK_NONE); 2122 r1 = sb->d[pindex % SWAP_META_PAGES]; 2123 if (r1 == SWAPBLK_NONE) 2124 return (SWAPBLK_NONE); 2125 if ((flags & SWM_POP) != 0) { 2126 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2127 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2128 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2129 rounddown(pindex, SWAP_META_PAGES)); 2130 uma_zfree(swblk_zone, sb); 2131 } 2132 } 2133 return (r1); 2134 } 2135 2136 /* 2137 * Returns the least page index which is greater than or equal to the 2138 * parameter pindex and for which there is a swap block allocated. 2139 * Returns object's size if the object's type is not swap or if there 2140 * are no allocated swap blocks for the object after the requested 2141 * pindex. 2142 */ 2143 vm_pindex_t 2144 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2145 { 2146 struct swblk *sb; 2147 int i; 2148 2149 VM_OBJECT_ASSERT_LOCKED(object); 2150 if (object->type != OBJT_SWAP) 2151 return (object->size); 2152 2153 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2154 rounddown(pindex, SWAP_META_PAGES)); 2155 if (sb == NULL) 2156 return (object->size); 2157 if (sb->p < pindex) { 2158 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2159 if (sb->d[i] != SWAPBLK_NONE) 2160 return (sb->p + i); 2161 } 2162 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2163 roundup(pindex, SWAP_META_PAGES)); 2164 if (sb == NULL) 2165 return (object->size); 2166 } 2167 for (i = 0; i < SWAP_META_PAGES; i++) { 2168 if (sb->d[i] != SWAPBLK_NONE) 2169 return (sb->p + i); 2170 } 2171 2172 /* 2173 * We get here if a swblk is present in the trie but it 2174 * doesn't map any blocks. 2175 */ 2176 MPASS(0); 2177 return (object->size); 2178 } 2179 2180 /* 2181 * System call swapon(name) enables swapping on device name, 2182 * which must be in the swdevsw. Return EBUSY 2183 * if already swapping on this device. 2184 */ 2185 #ifndef _SYS_SYSPROTO_H_ 2186 struct swapon_args { 2187 char *name; 2188 }; 2189 #endif 2190 2191 /* 2192 * MPSAFE 2193 */ 2194 /* ARGSUSED */ 2195 int 2196 sys_swapon(struct thread *td, struct swapon_args *uap) 2197 { 2198 struct vattr attr; 2199 struct vnode *vp; 2200 struct nameidata nd; 2201 int error; 2202 2203 error = priv_check(td, PRIV_SWAPON); 2204 if (error) 2205 return (error); 2206 2207 sx_xlock(&swdev_syscall_lock); 2208 2209 /* 2210 * Swap metadata may not fit in the KVM if we have physical 2211 * memory of >1GB. 2212 */ 2213 if (swblk_zone == NULL) { 2214 error = ENOMEM; 2215 goto done; 2216 } 2217 2218 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2219 uap->name, td); 2220 error = namei(&nd); 2221 if (error) 2222 goto done; 2223 2224 NDFREE(&nd, NDF_ONLY_PNBUF); 2225 vp = nd.ni_vp; 2226 2227 if (vn_isdisk(vp, &error)) { 2228 error = swapongeom(vp); 2229 } else if (vp->v_type == VREG && 2230 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2231 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2232 /* 2233 * Allow direct swapping to NFS regular files in the same 2234 * way that nfs_mountroot() sets up diskless swapping. 2235 */ 2236 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2237 } 2238 2239 if (error) 2240 vrele(vp); 2241 done: 2242 sx_xunlock(&swdev_syscall_lock); 2243 return (error); 2244 } 2245 2246 /* 2247 * Check that the total amount of swap currently configured does not 2248 * exceed half the theoretical maximum. If it does, print a warning 2249 * message. 2250 */ 2251 static void 2252 swapon_check_swzone(void) 2253 { 2254 2255 /* recommend using no more than half that amount */ 2256 if (swap_total > swap_maxpages / 2) { 2257 printf("warning: total configured swap (%lu pages) " 2258 "exceeds maximum recommended amount (%lu pages).\n", 2259 swap_total, swap_maxpages / 2); 2260 printf("warning: increase kern.maxswzone " 2261 "or reduce amount of swap.\n"); 2262 } 2263 } 2264 2265 static void 2266 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2267 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2268 { 2269 struct swdevt *sp, *tsp; 2270 swblk_t dvbase; 2271 u_long mblocks; 2272 2273 /* 2274 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2275 * First chop nblks off to page-align it, then convert. 2276 * 2277 * sw->sw_nblks is in page-sized chunks now too. 2278 */ 2279 nblks &= ~(ctodb(1) - 1); 2280 nblks = dbtoc(nblks); 2281 2282 /* 2283 * If we go beyond this, we get overflows in the radix 2284 * tree bitmap code. 2285 */ 2286 mblocks = 0x40000000 / BLIST_META_RADIX; 2287 if (nblks > mblocks) { 2288 printf( 2289 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2290 mblocks / 1024 / 1024 * PAGE_SIZE); 2291 nblks = mblocks; 2292 } 2293 2294 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2295 sp->sw_vp = vp; 2296 sp->sw_id = id; 2297 sp->sw_dev = dev; 2298 sp->sw_nblks = nblks; 2299 sp->sw_used = 0; 2300 sp->sw_strategy = strategy; 2301 sp->sw_close = close; 2302 sp->sw_flags = flags; 2303 2304 sp->sw_blist = blist_create(nblks, M_WAITOK); 2305 /* 2306 * Do not free the first blocks in order to avoid overwriting 2307 * any bsd label at the front of the partition 2308 */ 2309 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2310 nblks - howmany(BBSIZE, PAGE_SIZE)); 2311 2312 dvbase = 0; 2313 mtx_lock(&sw_dev_mtx); 2314 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2315 if (tsp->sw_end >= dvbase) { 2316 /* 2317 * We put one uncovered page between the devices 2318 * in order to definitively prevent any cross-device 2319 * I/O requests 2320 */ 2321 dvbase = tsp->sw_end + 1; 2322 } 2323 } 2324 sp->sw_first = dvbase; 2325 sp->sw_end = dvbase + nblks; 2326 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2327 nswapdev++; 2328 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2329 swap_total += nblks; 2330 swapon_check_swzone(); 2331 swp_sizecheck(); 2332 mtx_unlock(&sw_dev_mtx); 2333 EVENTHANDLER_INVOKE(swapon, sp); 2334 } 2335 2336 /* 2337 * SYSCALL: swapoff(devname) 2338 * 2339 * Disable swapping on the given device. 2340 * 2341 * XXX: Badly designed system call: it should use a device index 2342 * rather than filename as specification. We keep sw_vp around 2343 * only to make this work. 2344 */ 2345 #ifndef _SYS_SYSPROTO_H_ 2346 struct swapoff_args { 2347 char *name; 2348 }; 2349 #endif 2350 2351 /* 2352 * MPSAFE 2353 */ 2354 /* ARGSUSED */ 2355 int 2356 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2357 { 2358 struct vnode *vp; 2359 struct nameidata nd; 2360 struct swdevt *sp; 2361 int error; 2362 2363 error = priv_check(td, PRIV_SWAPOFF); 2364 if (error) 2365 return (error); 2366 2367 sx_xlock(&swdev_syscall_lock); 2368 2369 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2370 td); 2371 error = namei(&nd); 2372 if (error) 2373 goto done; 2374 NDFREE(&nd, NDF_ONLY_PNBUF); 2375 vp = nd.ni_vp; 2376 2377 mtx_lock(&sw_dev_mtx); 2378 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2379 if (sp->sw_vp == vp) 2380 break; 2381 } 2382 mtx_unlock(&sw_dev_mtx); 2383 if (sp == NULL) { 2384 error = EINVAL; 2385 goto done; 2386 } 2387 error = swapoff_one(sp, td->td_ucred); 2388 done: 2389 sx_xunlock(&swdev_syscall_lock); 2390 return (error); 2391 } 2392 2393 static int 2394 swapoff_one(struct swdevt *sp, struct ucred *cred) 2395 { 2396 u_long nblks; 2397 #ifdef MAC 2398 int error; 2399 #endif 2400 2401 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2402 #ifdef MAC 2403 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2404 error = mac_system_check_swapoff(cred, sp->sw_vp); 2405 (void) VOP_UNLOCK(sp->sw_vp, 0); 2406 if (error != 0) 2407 return (error); 2408 #endif 2409 nblks = sp->sw_nblks; 2410 2411 /* 2412 * We can turn off this swap device safely only if the 2413 * available virtual memory in the system will fit the amount 2414 * of data we will have to page back in, plus an epsilon so 2415 * the system doesn't become critically low on swap space. 2416 */ 2417 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2418 return (ENOMEM); 2419 2420 /* 2421 * Prevent further allocations on this device. 2422 */ 2423 mtx_lock(&sw_dev_mtx); 2424 sp->sw_flags |= SW_CLOSING; 2425 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2426 swap_total -= nblks; 2427 mtx_unlock(&sw_dev_mtx); 2428 2429 /* 2430 * Page in the contents of the device and close it. 2431 */ 2432 swap_pager_swapoff(sp); 2433 2434 sp->sw_close(curthread, sp); 2435 mtx_lock(&sw_dev_mtx); 2436 sp->sw_id = NULL; 2437 TAILQ_REMOVE(&swtailq, sp, sw_list); 2438 nswapdev--; 2439 if (nswapdev == 0) { 2440 swap_pager_full = 2; 2441 swap_pager_almost_full = 1; 2442 } 2443 if (swdevhd == sp) 2444 swdevhd = NULL; 2445 mtx_unlock(&sw_dev_mtx); 2446 blist_destroy(sp->sw_blist); 2447 free(sp, M_VMPGDATA); 2448 return (0); 2449 } 2450 2451 void 2452 swapoff_all(void) 2453 { 2454 struct swdevt *sp, *spt; 2455 const char *devname; 2456 int error; 2457 2458 sx_xlock(&swdev_syscall_lock); 2459 2460 mtx_lock(&sw_dev_mtx); 2461 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2462 mtx_unlock(&sw_dev_mtx); 2463 if (vn_isdisk(sp->sw_vp, NULL)) 2464 devname = devtoname(sp->sw_vp->v_rdev); 2465 else 2466 devname = "[file]"; 2467 error = swapoff_one(sp, thread0.td_ucred); 2468 if (error != 0) { 2469 printf("Cannot remove swap device %s (error=%d), " 2470 "skipping.\n", devname, error); 2471 } else if (bootverbose) { 2472 printf("Swap device %s removed.\n", devname); 2473 } 2474 mtx_lock(&sw_dev_mtx); 2475 } 2476 mtx_unlock(&sw_dev_mtx); 2477 2478 sx_xunlock(&swdev_syscall_lock); 2479 } 2480 2481 void 2482 swap_pager_status(int *total, int *used) 2483 { 2484 struct swdevt *sp; 2485 2486 *total = 0; 2487 *used = 0; 2488 mtx_lock(&sw_dev_mtx); 2489 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2490 *total += sp->sw_nblks; 2491 *used += sp->sw_used; 2492 } 2493 mtx_unlock(&sw_dev_mtx); 2494 } 2495 2496 int 2497 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2498 { 2499 struct swdevt *sp; 2500 const char *tmp_devname; 2501 int error, n; 2502 2503 n = 0; 2504 error = ENOENT; 2505 mtx_lock(&sw_dev_mtx); 2506 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2507 if (n != name) { 2508 n++; 2509 continue; 2510 } 2511 xs->xsw_version = XSWDEV_VERSION; 2512 xs->xsw_dev = sp->sw_dev; 2513 xs->xsw_flags = sp->sw_flags; 2514 xs->xsw_nblks = sp->sw_nblks; 2515 xs->xsw_used = sp->sw_used; 2516 if (devname != NULL) { 2517 if (vn_isdisk(sp->sw_vp, NULL)) 2518 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2519 else 2520 tmp_devname = "[file]"; 2521 strncpy(devname, tmp_devname, len); 2522 } 2523 error = 0; 2524 break; 2525 } 2526 mtx_unlock(&sw_dev_mtx); 2527 return (error); 2528 } 2529 2530 #if defined(COMPAT_FREEBSD11) 2531 #define XSWDEV_VERSION_11 1 2532 struct xswdev11 { 2533 u_int xsw_version; 2534 uint32_t xsw_dev; 2535 int xsw_flags; 2536 int xsw_nblks; 2537 int xsw_used; 2538 }; 2539 #endif 2540 2541 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2542 struct xswdev32 { 2543 u_int xsw_version; 2544 u_int xsw_dev1, xsw_dev2; 2545 int xsw_flags; 2546 int xsw_nblks; 2547 int xsw_used; 2548 }; 2549 #endif 2550 2551 static int 2552 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2553 { 2554 struct xswdev xs; 2555 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2556 struct xswdev32 xs32; 2557 #endif 2558 #if defined(COMPAT_FREEBSD11) 2559 struct xswdev11 xs11; 2560 #endif 2561 int error; 2562 2563 if (arg2 != 1) /* name length */ 2564 return (EINVAL); 2565 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2566 if (error != 0) 2567 return (error); 2568 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2569 if (req->oldlen == sizeof(xs32)) { 2570 xs32.xsw_version = XSWDEV_VERSION; 2571 xs32.xsw_dev1 = xs.xsw_dev; 2572 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2573 xs32.xsw_flags = xs.xsw_flags; 2574 xs32.xsw_nblks = xs.xsw_nblks; 2575 xs32.xsw_used = xs.xsw_used; 2576 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2577 return (error); 2578 } 2579 #endif 2580 #if defined(COMPAT_FREEBSD11) 2581 if (req->oldlen == sizeof(xs11)) { 2582 xs11.xsw_version = XSWDEV_VERSION_11; 2583 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2584 xs11.xsw_flags = xs.xsw_flags; 2585 xs11.xsw_nblks = xs.xsw_nblks; 2586 xs11.xsw_used = xs.xsw_used; 2587 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2588 return (error); 2589 } 2590 #endif 2591 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2592 return (error); 2593 } 2594 2595 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2596 "Number of swap devices"); 2597 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2598 sysctl_vm_swap_info, 2599 "Swap statistics by device"); 2600 2601 /* 2602 * Count the approximate swap usage in pages for a vmspace. The 2603 * shadowed or not yet copied on write swap blocks are not accounted. 2604 * The map must be locked. 2605 */ 2606 long 2607 vmspace_swap_count(struct vmspace *vmspace) 2608 { 2609 vm_map_t map; 2610 vm_map_entry_t cur; 2611 vm_object_t object; 2612 struct swblk *sb; 2613 vm_pindex_t e, pi; 2614 long count; 2615 int i; 2616 2617 map = &vmspace->vm_map; 2618 count = 0; 2619 2620 VM_MAP_ENTRY_FOREACH(cur, map) { 2621 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2622 continue; 2623 object = cur->object.vm_object; 2624 if (object == NULL || object->type != OBJT_SWAP) 2625 continue; 2626 VM_OBJECT_RLOCK(object); 2627 if (object->type != OBJT_SWAP) 2628 goto unlock; 2629 pi = OFF_TO_IDX(cur->offset); 2630 e = pi + OFF_TO_IDX(cur->end - cur->start); 2631 for (;; pi = sb->p + SWAP_META_PAGES) { 2632 sb = SWAP_PCTRIE_LOOKUP_GE( 2633 &object->un_pager.swp.swp_blks, pi); 2634 if (sb == NULL || sb->p >= e) 2635 break; 2636 for (i = 0; i < SWAP_META_PAGES; i++) { 2637 if (sb->p + i < e && 2638 sb->d[i] != SWAPBLK_NONE) 2639 count++; 2640 } 2641 } 2642 unlock: 2643 VM_OBJECT_RUNLOCK(object); 2644 } 2645 return (count); 2646 } 2647 2648 /* 2649 * GEOM backend 2650 * 2651 * Swapping onto disk devices. 2652 * 2653 */ 2654 2655 static g_orphan_t swapgeom_orphan; 2656 2657 static struct g_class g_swap_class = { 2658 .name = "SWAP", 2659 .version = G_VERSION, 2660 .orphan = swapgeom_orphan, 2661 }; 2662 2663 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2664 2665 2666 static void 2667 swapgeom_close_ev(void *arg, int flags) 2668 { 2669 struct g_consumer *cp; 2670 2671 cp = arg; 2672 g_access(cp, -1, -1, 0); 2673 g_detach(cp); 2674 g_destroy_consumer(cp); 2675 } 2676 2677 /* 2678 * Add a reference to the g_consumer for an inflight transaction. 2679 */ 2680 static void 2681 swapgeom_acquire(struct g_consumer *cp) 2682 { 2683 2684 mtx_assert(&sw_dev_mtx, MA_OWNED); 2685 cp->index++; 2686 } 2687 2688 /* 2689 * Remove a reference from the g_consumer. Post a close event if all 2690 * references go away, since the function might be called from the 2691 * biodone context. 2692 */ 2693 static void 2694 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2695 { 2696 2697 mtx_assert(&sw_dev_mtx, MA_OWNED); 2698 cp->index--; 2699 if (cp->index == 0) { 2700 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2701 sp->sw_id = NULL; 2702 } 2703 } 2704 2705 static void 2706 swapgeom_done(struct bio *bp2) 2707 { 2708 struct swdevt *sp; 2709 struct buf *bp; 2710 struct g_consumer *cp; 2711 2712 bp = bp2->bio_caller2; 2713 cp = bp2->bio_from; 2714 bp->b_ioflags = bp2->bio_flags; 2715 if (bp2->bio_error) 2716 bp->b_ioflags |= BIO_ERROR; 2717 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2718 bp->b_error = bp2->bio_error; 2719 bp->b_caller1 = NULL; 2720 bufdone(bp); 2721 sp = bp2->bio_caller1; 2722 mtx_lock(&sw_dev_mtx); 2723 swapgeom_release(cp, sp); 2724 mtx_unlock(&sw_dev_mtx); 2725 g_destroy_bio(bp2); 2726 } 2727 2728 static void 2729 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2730 { 2731 struct bio *bio; 2732 struct g_consumer *cp; 2733 2734 mtx_lock(&sw_dev_mtx); 2735 cp = sp->sw_id; 2736 if (cp == NULL) { 2737 mtx_unlock(&sw_dev_mtx); 2738 bp->b_error = ENXIO; 2739 bp->b_ioflags |= BIO_ERROR; 2740 bufdone(bp); 2741 return; 2742 } 2743 swapgeom_acquire(cp); 2744 mtx_unlock(&sw_dev_mtx); 2745 if (bp->b_iocmd == BIO_WRITE) 2746 bio = g_new_bio(); 2747 else 2748 bio = g_alloc_bio(); 2749 if (bio == NULL) { 2750 mtx_lock(&sw_dev_mtx); 2751 swapgeom_release(cp, sp); 2752 mtx_unlock(&sw_dev_mtx); 2753 bp->b_error = ENOMEM; 2754 bp->b_ioflags |= BIO_ERROR; 2755 printf("swap_pager: cannot allocate bio\n"); 2756 bufdone(bp); 2757 return; 2758 } 2759 2760 bp->b_caller1 = bio; 2761 bio->bio_caller1 = sp; 2762 bio->bio_caller2 = bp; 2763 bio->bio_cmd = bp->b_iocmd; 2764 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2765 bio->bio_length = bp->b_bcount; 2766 bio->bio_done = swapgeom_done; 2767 if (!buf_mapped(bp)) { 2768 bio->bio_ma = bp->b_pages; 2769 bio->bio_data = unmapped_buf; 2770 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2771 bio->bio_ma_n = bp->b_npages; 2772 bio->bio_flags |= BIO_UNMAPPED; 2773 } else { 2774 bio->bio_data = bp->b_data; 2775 bio->bio_ma = NULL; 2776 } 2777 g_io_request(bio, cp); 2778 return; 2779 } 2780 2781 static void 2782 swapgeom_orphan(struct g_consumer *cp) 2783 { 2784 struct swdevt *sp; 2785 int destroy; 2786 2787 mtx_lock(&sw_dev_mtx); 2788 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2789 if (sp->sw_id == cp) { 2790 sp->sw_flags |= SW_CLOSING; 2791 break; 2792 } 2793 } 2794 /* 2795 * Drop reference we were created with. Do directly since we're in a 2796 * special context where we don't have to queue the call to 2797 * swapgeom_close_ev(). 2798 */ 2799 cp->index--; 2800 destroy = ((sp != NULL) && (cp->index == 0)); 2801 if (destroy) 2802 sp->sw_id = NULL; 2803 mtx_unlock(&sw_dev_mtx); 2804 if (destroy) 2805 swapgeom_close_ev(cp, 0); 2806 } 2807 2808 static void 2809 swapgeom_close(struct thread *td, struct swdevt *sw) 2810 { 2811 struct g_consumer *cp; 2812 2813 mtx_lock(&sw_dev_mtx); 2814 cp = sw->sw_id; 2815 sw->sw_id = NULL; 2816 mtx_unlock(&sw_dev_mtx); 2817 2818 /* 2819 * swapgeom_close() may be called from the biodone context, 2820 * where we cannot perform topology changes. Delegate the 2821 * work to the events thread. 2822 */ 2823 if (cp != NULL) 2824 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2825 } 2826 2827 static int 2828 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2829 { 2830 struct g_provider *pp; 2831 struct g_consumer *cp; 2832 static struct g_geom *gp; 2833 struct swdevt *sp; 2834 u_long nblks; 2835 int error; 2836 2837 pp = g_dev_getprovider(dev); 2838 if (pp == NULL) 2839 return (ENODEV); 2840 mtx_lock(&sw_dev_mtx); 2841 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2842 cp = sp->sw_id; 2843 if (cp != NULL && cp->provider == pp) { 2844 mtx_unlock(&sw_dev_mtx); 2845 return (EBUSY); 2846 } 2847 } 2848 mtx_unlock(&sw_dev_mtx); 2849 if (gp == NULL) 2850 gp = g_new_geomf(&g_swap_class, "swap"); 2851 cp = g_new_consumer(gp); 2852 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2853 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2854 g_attach(cp, pp); 2855 /* 2856 * XXX: Every time you think you can improve the margin for 2857 * footshooting, somebody depends on the ability to do so: 2858 * savecore(8) wants to write to our swapdev so we cannot 2859 * set an exclusive count :-( 2860 */ 2861 error = g_access(cp, 1, 1, 0); 2862 if (error != 0) { 2863 g_detach(cp); 2864 g_destroy_consumer(cp); 2865 return (error); 2866 } 2867 nblks = pp->mediasize / DEV_BSIZE; 2868 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2869 swapgeom_close, dev2udev(dev), 2870 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2871 return (0); 2872 } 2873 2874 static int 2875 swapongeom(struct vnode *vp) 2876 { 2877 int error; 2878 2879 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2880 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2881 error = ENOENT; 2882 } else { 2883 g_topology_lock(); 2884 error = swapongeom_locked(vp->v_rdev, vp); 2885 g_topology_unlock(); 2886 } 2887 VOP_UNLOCK(vp, 0); 2888 return (error); 2889 } 2890 2891 /* 2892 * VNODE backend 2893 * 2894 * This is used mainly for network filesystem (read: probably only tested 2895 * with NFS) swapfiles. 2896 * 2897 */ 2898 2899 static void 2900 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2901 { 2902 struct vnode *vp2; 2903 2904 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2905 2906 vp2 = sp->sw_id; 2907 vhold(vp2); 2908 if (bp->b_iocmd == BIO_WRITE) { 2909 if (bp->b_bufobj) 2910 bufobj_wdrop(bp->b_bufobj); 2911 bufobj_wref(&vp2->v_bufobj); 2912 } 2913 if (bp->b_bufobj != &vp2->v_bufobj) 2914 bp->b_bufobj = &vp2->v_bufobj; 2915 bp->b_vp = vp2; 2916 bp->b_iooffset = dbtob(bp->b_blkno); 2917 bstrategy(bp); 2918 return; 2919 } 2920 2921 static void 2922 swapdev_close(struct thread *td, struct swdevt *sp) 2923 { 2924 2925 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2926 vrele(sp->sw_vp); 2927 } 2928 2929 2930 static int 2931 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2932 { 2933 struct swdevt *sp; 2934 int error; 2935 2936 if (nblks == 0) 2937 return (ENXIO); 2938 mtx_lock(&sw_dev_mtx); 2939 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2940 if (sp->sw_id == vp) { 2941 mtx_unlock(&sw_dev_mtx); 2942 return (EBUSY); 2943 } 2944 } 2945 mtx_unlock(&sw_dev_mtx); 2946 2947 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2948 #ifdef MAC 2949 error = mac_system_check_swapon(td->td_ucred, vp); 2950 if (error == 0) 2951 #endif 2952 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2953 (void) VOP_UNLOCK(vp, 0); 2954 if (error) 2955 return (error); 2956 2957 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2958 NODEV, 0); 2959 return (0); 2960 } 2961 2962 static int 2963 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2964 { 2965 int error, new, n; 2966 2967 new = nsw_wcount_async_max; 2968 error = sysctl_handle_int(oidp, &new, 0, req); 2969 if (error != 0 || req->newptr == NULL) 2970 return (error); 2971 2972 if (new > nswbuf / 2 || new < 1) 2973 return (EINVAL); 2974 2975 mtx_lock(&swbuf_mtx); 2976 while (nsw_wcount_async_max != new) { 2977 /* 2978 * Adjust difference. If the current async count is too low, 2979 * we will need to sqeeze our update slowly in. Sleep with a 2980 * higher priority than getpbuf() to finish faster. 2981 */ 2982 n = new - nsw_wcount_async_max; 2983 if (nsw_wcount_async + n >= 0) { 2984 nsw_wcount_async += n; 2985 nsw_wcount_async_max += n; 2986 wakeup(&nsw_wcount_async); 2987 } else { 2988 nsw_wcount_async_max -= nsw_wcount_async; 2989 nsw_wcount_async = 0; 2990 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 2991 "swpsysctl", 0); 2992 } 2993 } 2994 mtx_unlock(&swbuf_mtx); 2995 2996 return (0); 2997 } 2998 2999 static void 3000 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3001 vm_offset_t end) 3002 { 3003 3004 VM_OBJECT_WLOCK(object); 3005 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3006 ("Splittable object with writecount")); 3007 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3008 VM_OBJECT_WUNLOCK(object); 3009 } 3010 3011 static void 3012 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3013 vm_offset_t end) 3014 { 3015 3016 VM_OBJECT_WLOCK(object); 3017 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3018 ("Splittable object with writecount")); 3019 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3020 VM_OBJECT_WUNLOCK(object); 3021 } 3022