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 swap_maxpages = n * SWAP_META_PAGES; 594 swzone = n * sizeof(struct swblk); 595 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 596 printf("Cannot reserve swap pctrie zone, " 597 "reduce kern.maxswzone.\n"); 598 } 599 600 static vm_object_t 601 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 602 vm_ooffset_t offset) 603 { 604 vm_object_t object; 605 606 if (cred != NULL) { 607 if (!swap_reserve_by_cred(size, cred)) 608 return (NULL); 609 crhold(cred); 610 } 611 612 /* 613 * The un_pager.swp.swp_blks trie is initialized by 614 * vm_object_allocate() to ensure the correct order of 615 * visibility to other threads. 616 */ 617 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 618 PAGE_MASK + size)); 619 620 object->un_pager.swp.writemappings = 0; 621 object->handle = handle; 622 if (cred != NULL) { 623 object->cred = cred; 624 object->charge = size; 625 } 626 return (object); 627 } 628 629 /* 630 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 631 * its metadata structures. 632 * 633 * This routine is called from the mmap and fork code to create a new 634 * OBJT_SWAP object. 635 * 636 * This routine must ensure that no live duplicate is created for 637 * the named object request, which is protected against by 638 * holding the sw_alloc_sx lock in case handle != NULL. 639 */ 640 static vm_object_t 641 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 642 vm_ooffset_t offset, struct ucred *cred) 643 { 644 vm_object_t object; 645 646 if (handle != NULL) { 647 /* 648 * Reference existing named region or allocate new one. There 649 * should not be a race here against swp_pager_meta_build() 650 * as called from vm_page_remove() in regards to the lookup 651 * of the handle. 652 */ 653 sx_xlock(&sw_alloc_sx); 654 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 655 if (object == NULL) { 656 object = swap_pager_alloc_init(handle, cred, size, 657 offset); 658 if (object != NULL) { 659 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 660 object, pager_object_list); 661 } 662 } 663 sx_xunlock(&sw_alloc_sx); 664 } else { 665 object = swap_pager_alloc_init(handle, cred, size, offset); 666 } 667 return (object); 668 } 669 670 /* 671 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 672 * 673 * The swap backing for the object is destroyed. The code is 674 * designed such that we can reinstantiate it later, but this 675 * routine is typically called only when the entire object is 676 * about to be destroyed. 677 * 678 * The object must be locked. 679 */ 680 static void 681 swap_pager_dealloc(vm_object_t object) 682 { 683 684 VM_OBJECT_ASSERT_WLOCKED(object); 685 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 686 687 /* 688 * Remove from list right away so lookups will fail if we block for 689 * pageout completion. 690 */ 691 if (object->handle != NULL) { 692 VM_OBJECT_WUNLOCK(object); 693 sx_xlock(&sw_alloc_sx); 694 TAILQ_REMOVE(NOBJLIST(object->handle), object, 695 pager_object_list); 696 sx_xunlock(&sw_alloc_sx); 697 VM_OBJECT_WLOCK(object); 698 } 699 700 vm_object_pip_wait(object, "swpdea"); 701 702 /* 703 * Free all remaining metadata. We only bother to free it from 704 * the swap meta data. We do not attempt to free swapblk's still 705 * associated with vm_page_t's for this object. We do not care 706 * if paging is still in progress on some objects. 707 */ 708 swp_pager_meta_free_all(object); 709 object->handle = NULL; 710 object->type = OBJT_DEAD; 711 } 712 713 /************************************************************************ 714 * SWAP PAGER BITMAP ROUTINES * 715 ************************************************************************/ 716 717 /* 718 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 719 * 720 * Allocate swap for up to the requested number of pages, and at 721 * least a minimum number of pages. The starting swap block number 722 * (a page index) is returned or SWAPBLK_NONE if the allocation 723 * failed. 724 * 725 * Also has the side effect of advising that somebody made a mistake 726 * when they configured swap and didn't configure enough. 727 * 728 * This routine may not sleep. 729 * 730 * We allocate in round-robin fashion from the configured devices. 731 */ 732 static daddr_t 733 swp_pager_getswapspace(int *io_npages, int limit) 734 { 735 daddr_t blk; 736 struct swdevt *sp; 737 int mpages, npages; 738 739 blk = SWAPBLK_NONE; 740 mpages = *io_npages; 741 npages = imin(BLIST_MAX_ALLOC, mpages); 742 mtx_lock(&sw_dev_mtx); 743 sp = swdevhd; 744 while (!TAILQ_EMPTY(&swtailq)) { 745 if (sp == NULL) 746 sp = TAILQ_FIRST(&swtailq); 747 if ((sp->sw_flags & SW_CLOSING) == 0) 748 blk = blist_alloc(sp->sw_blist, &npages, mpages); 749 if (blk != SWAPBLK_NONE) 750 break; 751 sp = TAILQ_NEXT(sp, sw_list); 752 if (swdevhd == sp) { 753 if (npages <= limit) 754 break; 755 mpages = npages - 1; 756 npages >>= 1; 757 } 758 } 759 if (blk != SWAPBLK_NONE) { 760 *io_npages = npages; 761 blk += sp->sw_first; 762 sp->sw_used += npages; 763 swap_pager_avail -= npages; 764 swp_sizecheck(); 765 swdevhd = TAILQ_NEXT(sp, sw_list); 766 } else { 767 if (swap_pager_full != 2) { 768 printf("swp_pager_getswapspace(%d): failed\n", 769 *io_npages); 770 swap_pager_full = 2; 771 swap_pager_almost_full = 1; 772 } 773 swdevhd = NULL; 774 } 775 mtx_unlock(&sw_dev_mtx); 776 return (blk); 777 } 778 779 static bool 780 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 781 { 782 783 return (blk >= sp->sw_first && blk < sp->sw_end); 784 } 785 786 static void 787 swp_pager_strategy(struct buf *bp) 788 { 789 struct swdevt *sp; 790 791 mtx_lock(&sw_dev_mtx); 792 TAILQ_FOREACH(sp, &swtailq, sw_list) { 793 if (swp_pager_isondev(bp->b_blkno, sp)) { 794 mtx_unlock(&sw_dev_mtx); 795 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 796 unmapped_buf_allowed) { 797 bp->b_data = unmapped_buf; 798 bp->b_offset = 0; 799 } else { 800 pmap_qenter((vm_offset_t)bp->b_data, 801 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 802 } 803 sp->sw_strategy(bp, sp); 804 return; 805 } 806 } 807 panic("Swapdev not found"); 808 } 809 810 811 /* 812 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 813 * 814 * This routine returns the specified swap blocks back to the bitmap. 815 * 816 * This routine may not sleep. 817 */ 818 static void 819 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 820 { 821 struct swdevt *sp; 822 823 if (npages == 0) 824 return; 825 mtx_lock(&sw_dev_mtx); 826 TAILQ_FOREACH(sp, &swtailq, sw_list) { 827 if (swp_pager_isondev(blk, sp)) { 828 sp->sw_used -= npages; 829 /* 830 * If we are attempting to stop swapping on 831 * this device, we don't want to mark any 832 * blocks free lest they be reused. 833 */ 834 if ((sp->sw_flags & SW_CLOSING) == 0) { 835 blist_free(sp->sw_blist, blk - sp->sw_first, 836 npages); 837 swap_pager_avail += npages; 838 swp_sizecheck(); 839 } 840 mtx_unlock(&sw_dev_mtx); 841 return; 842 } 843 } 844 panic("Swapdev not found"); 845 } 846 847 /* 848 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 849 */ 850 static int 851 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 852 { 853 struct sbuf sbuf; 854 struct swdevt *sp; 855 const char *devname; 856 int error; 857 858 error = sysctl_wire_old_buffer(req, 0); 859 if (error != 0) 860 return (error); 861 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 862 mtx_lock(&sw_dev_mtx); 863 TAILQ_FOREACH(sp, &swtailq, sw_list) { 864 if (vn_isdisk(sp->sw_vp, NULL)) 865 devname = devtoname(sp->sw_vp->v_rdev); 866 else 867 devname = "[file]"; 868 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 869 blist_stats(sp->sw_blist, &sbuf); 870 } 871 mtx_unlock(&sw_dev_mtx); 872 error = sbuf_finish(&sbuf); 873 sbuf_delete(&sbuf); 874 return (error); 875 } 876 877 /* 878 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 879 * range within an object. 880 * 881 * This is a globally accessible routine. 882 * 883 * This routine removes swapblk assignments from swap metadata. 884 * 885 * The external callers of this routine typically have already destroyed 886 * or renamed vm_page_t's associated with this range in the object so 887 * we should be ok. 888 * 889 * The object must be locked. 890 */ 891 void 892 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 893 { 894 895 swp_pager_meta_free(object, start, size); 896 } 897 898 /* 899 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 900 * 901 * Assigns swap blocks to the specified range within the object. The 902 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 903 * 904 * Returns 0 on success, -1 on failure. 905 */ 906 int 907 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 908 { 909 daddr_t addr, blk, n_free, s_free; 910 int i, j, n; 911 912 swp_pager_init_freerange(&s_free, &n_free); 913 VM_OBJECT_WLOCK(object); 914 for (i = 0; i < size; i += n) { 915 n = size - i; 916 blk = swp_pager_getswapspace(&n, 1); 917 if (blk == SWAPBLK_NONE) { 918 swp_pager_meta_free(object, start, i); 919 VM_OBJECT_WUNLOCK(object); 920 return (-1); 921 } 922 for (j = 0; j < n; ++j) { 923 addr = swp_pager_meta_build(object, 924 start + i + j, blk + j); 925 if (addr != SWAPBLK_NONE) 926 swp_pager_update_freerange(&s_free, &n_free, 927 addr); 928 } 929 } 930 swp_pager_freeswapspace(s_free, n_free); 931 VM_OBJECT_WUNLOCK(object); 932 return (0); 933 } 934 935 /* 936 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 937 * and destroy the source. 938 * 939 * Copy any valid swapblks from the source to the destination. In 940 * cases where both the source and destination have a valid swapblk, 941 * we keep the destination's. 942 * 943 * This routine is allowed to sleep. It may sleep allocating metadata 944 * indirectly through swp_pager_meta_build() or if paging is still in 945 * progress on the source. 946 * 947 * The source object contains no vm_page_t's (which is just as well) 948 * 949 * The source object is of type OBJT_SWAP. 950 * 951 * The source and destination objects must be locked. 952 * Both object locks may temporarily be released. 953 */ 954 void 955 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 956 vm_pindex_t offset, int destroysource) 957 { 958 vm_pindex_t i; 959 daddr_t dstaddr, n_free, s_free, srcaddr; 960 961 VM_OBJECT_ASSERT_WLOCKED(srcobject); 962 VM_OBJECT_ASSERT_WLOCKED(dstobject); 963 964 /* 965 * If destroysource is set, we remove the source object from the 966 * swap_pager internal queue now. 967 */ 968 if (destroysource && srcobject->handle != NULL) { 969 vm_object_pip_add(srcobject, 1); 970 VM_OBJECT_WUNLOCK(srcobject); 971 vm_object_pip_add(dstobject, 1); 972 VM_OBJECT_WUNLOCK(dstobject); 973 sx_xlock(&sw_alloc_sx); 974 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 975 pager_object_list); 976 sx_xunlock(&sw_alloc_sx); 977 VM_OBJECT_WLOCK(dstobject); 978 vm_object_pip_wakeup(dstobject); 979 VM_OBJECT_WLOCK(srcobject); 980 vm_object_pip_wakeup(srcobject); 981 } 982 983 /* 984 * Transfer source to destination. 985 */ 986 swp_pager_init_freerange(&s_free, &n_free); 987 for (i = 0; i < dstobject->size; ++i) { 988 srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP); 989 if (srcaddr == SWAPBLK_NONE) 990 continue; 991 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 992 if (dstaddr != SWAPBLK_NONE) { 993 /* 994 * Destination has valid swapblk or it is represented 995 * by a resident page. We destroy the source block. 996 */ 997 swp_pager_update_freerange(&s_free, &n_free, srcaddr); 998 continue; 999 } 1000 1001 /* 1002 * Destination has no swapblk and is not resident, 1003 * copy source. 1004 * 1005 * swp_pager_meta_build() can sleep. 1006 */ 1007 vm_object_pip_add(srcobject, 1); 1008 VM_OBJECT_WUNLOCK(srcobject); 1009 vm_object_pip_add(dstobject, 1); 1010 dstaddr = swp_pager_meta_build(dstobject, i, srcaddr); 1011 KASSERT(dstaddr == SWAPBLK_NONE, 1012 ("Unexpected destination swapblk")); 1013 vm_object_pip_wakeup(dstobject); 1014 VM_OBJECT_WLOCK(srcobject); 1015 vm_object_pip_wakeup(srcobject); 1016 } 1017 swp_pager_freeswapspace(s_free, n_free); 1018 1019 /* 1020 * Free left over swap blocks in source. 1021 * 1022 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1023 * double-remove the object from the swap queues. 1024 */ 1025 if (destroysource) { 1026 swp_pager_meta_free_all(srcobject); 1027 /* 1028 * Reverting the type is not necessary, the caller is going 1029 * to destroy srcobject directly, but I'm doing it here 1030 * for consistency since we've removed the object from its 1031 * queues. 1032 */ 1033 srcobject->type = OBJT_DEFAULT; 1034 } 1035 } 1036 1037 /* 1038 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1039 * the requested page. 1040 * 1041 * We determine whether good backing store exists for the requested 1042 * page and return TRUE if it does, FALSE if it doesn't. 1043 * 1044 * If TRUE, we also try to determine how much valid, contiguous backing 1045 * store exists before and after the requested page. 1046 */ 1047 static boolean_t 1048 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1049 int *after) 1050 { 1051 daddr_t blk, blk0; 1052 int i; 1053 1054 VM_OBJECT_ASSERT_LOCKED(object); 1055 1056 /* 1057 * do we have good backing store at the requested index ? 1058 */ 1059 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1060 if (blk0 == SWAPBLK_NONE) { 1061 if (before) 1062 *before = 0; 1063 if (after) 1064 *after = 0; 1065 return (FALSE); 1066 } 1067 1068 /* 1069 * find backwards-looking contiguous good backing store 1070 */ 1071 if (before != NULL) { 1072 for (i = 1; i < SWB_NPAGES; i++) { 1073 if (i > pindex) 1074 break; 1075 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1076 if (blk != blk0 - i) 1077 break; 1078 } 1079 *before = i - 1; 1080 } 1081 1082 /* 1083 * find forward-looking contiguous good backing store 1084 */ 1085 if (after != NULL) { 1086 for (i = 1; i < SWB_NPAGES; i++) { 1087 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1088 if (blk != blk0 + i) 1089 break; 1090 } 1091 *after = i - 1; 1092 } 1093 return (TRUE); 1094 } 1095 1096 /* 1097 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1098 * 1099 * This removes any associated swap backing store, whether valid or 1100 * not, from the page. 1101 * 1102 * This routine is typically called when a page is made dirty, at 1103 * which point any associated swap can be freed. MADV_FREE also 1104 * calls us in a special-case situation 1105 * 1106 * NOTE!!! If the page is clean and the swap was valid, the caller 1107 * should make the page dirty before calling this routine. This routine 1108 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1109 * depends on it. 1110 * 1111 * This routine may not sleep. 1112 * 1113 * The object containing the page must be locked. 1114 */ 1115 static void 1116 swap_pager_unswapped(vm_page_t m) 1117 { 1118 daddr_t srcaddr; 1119 1120 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP); 1121 if (srcaddr != SWAPBLK_NONE) 1122 swp_pager_freeswapspace(srcaddr, 1); 1123 } 1124 1125 /* 1126 * swap_pager_getpages() - bring pages in from swap 1127 * 1128 * Attempt to page in the pages in array "ma" of length "count". The 1129 * caller may optionally specify that additional pages preceding and 1130 * succeeding the specified range be paged in. The number of such pages 1131 * is returned in the "rbehind" and "rahead" parameters, and they will 1132 * be in the inactive queue upon return. 1133 * 1134 * The pages in "ma" must be busied and will remain busied upon return. 1135 */ 1136 static int 1137 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1138 int *rahead) 1139 { 1140 struct buf *bp; 1141 vm_page_t bm, mpred, msucc, p; 1142 vm_pindex_t pindex; 1143 daddr_t blk; 1144 int i, maxahead, maxbehind, reqcount; 1145 1146 reqcount = count; 1147 1148 /* 1149 * Determine the final number of read-behind pages and 1150 * allocate them BEFORE releasing the object lock. Otherwise, 1151 * there can be a problematic race with vm_object_split(). 1152 * Specifically, vm_object_split() might first transfer pages 1153 * that precede ma[0] in the current object to a new object, 1154 * and then this function incorrectly recreates those pages as 1155 * read-behind pages in the current object. 1156 */ 1157 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1158 return (VM_PAGER_FAIL); 1159 1160 /* 1161 * Clip the readahead and readbehind ranges to exclude resident pages. 1162 */ 1163 if (rahead != NULL) { 1164 KASSERT(reqcount - 1 <= maxahead, 1165 ("page count %d extends beyond swap block", reqcount)); 1166 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1167 pindex = ma[reqcount - 1]->pindex; 1168 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1169 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1170 *rahead = msucc->pindex - pindex - 1; 1171 } 1172 if (rbehind != NULL) { 1173 *rbehind = imin(*rbehind, maxbehind); 1174 pindex = ma[0]->pindex; 1175 mpred = TAILQ_PREV(ma[0], pglist, listq); 1176 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1177 *rbehind = pindex - mpred->pindex - 1; 1178 } 1179 1180 bm = ma[0]; 1181 for (i = 0; i < count; i++) 1182 ma[i]->oflags |= VPO_SWAPINPROG; 1183 1184 /* 1185 * Allocate readahead and readbehind pages. 1186 */ 1187 if (rbehind != NULL) { 1188 for (i = 1; i <= *rbehind; i++) { 1189 p = vm_page_alloc(object, ma[0]->pindex - i, 1190 VM_ALLOC_NORMAL); 1191 if (p == NULL) 1192 break; 1193 p->oflags |= VPO_SWAPINPROG; 1194 bm = p; 1195 } 1196 *rbehind = i - 1; 1197 } 1198 if (rahead != NULL) { 1199 for (i = 0; i < *rahead; i++) { 1200 p = vm_page_alloc(object, 1201 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1202 if (p == NULL) 1203 break; 1204 p->oflags |= VPO_SWAPINPROG; 1205 } 1206 *rahead = i; 1207 } 1208 if (rbehind != NULL) 1209 count += *rbehind; 1210 if (rahead != NULL) 1211 count += *rahead; 1212 1213 vm_object_pip_add(object, count); 1214 1215 pindex = bm->pindex; 1216 blk = swp_pager_meta_ctl(object, pindex, 0); 1217 KASSERT(blk != SWAPBLK_NONE, 1218 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1219 1220 VM_OBJECT_WUNLOCK(object); 1221 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1222 /* Pages cannot leave the object while busy. */ 1223 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1224 MPASS(p->pindex == bm->pindex + i); 1225 bp->b_pages[i] = p; 1226 } 1227 1228 bp->b_flags |= B_PAGING; 1229 bp->b_iocmd = BIO_READ; 1230 bp->b_iodone = swp_pager_async_iodone; 1231 bp->b_rcred = crhold(thread0.td_ucred); 1232 bp->b_wcred = crhold(thread0.td_ucred); 1233 bp->b_blkno = blk; 1234 bp->b_bcount = PAGE_SIZE * count; 1235 bp->b_bufsize = PAGE_SIZE * count; 1236 bp->b_npages = count; 1237 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1238 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1239 1240 VM_CNT_INC(v_swapin); 1241 VM_CNT_ADD(v_swappgsin, count); 1242 1243 /* 1244 * perform the I/O. NOTE!!! bp cannot be considered valid after 1245 * this point because we automatically release it on completion. 1246 * Instead, we look at the one page we are interested in which we 1247 * still hold a lock on even through the I/O completion. 1248 * 1249 * The other pages in our ma[] array are also released on completion, 1250 * so we cannot assume they are valid anymore either. 1251 * 1252 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1253 */ 1254 BUF_KERNPROC(bp); 1255 swp_pager_strategy(bp); 1256 1257 /* 1258 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1259 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1260 * is set in the metadata for each page in the request. 1261 */ 1262 VM_OBJECT_WLOCK(object); 1263 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1264 ma[0]->oflags |= VPO_SWAPSLEEP; 1265 VM_CNT_INC(v_intrans); 1266 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1267 "swread", hz * 20)) { 1268 printf( 1269 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1270 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1271 } 1272 } 1273 1274 /* 1275 * If we had an unrecoverable read error pages will not be valid. 1276 */ 1277 for (i = 0; i < reqcount; i++) 1278 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1279 return (VM_PAGER_ERROR); 1280 1281 return (VM_PAGER_OK); 1282 1283 /* 1284 * A final note: in a low swap situation, we cannot deallocate swap 1285 * and mark a page dirty here because the caller is likely to mark 1286 * the page clean when we return, causing the page to possibly revert 1287 * to all-zero's later. 1288 */ 1289 } 1290 1291 /* 1292 * swap_pager_getpages_async(): 1293 * 1294 * Right now this is emulation of asynchronous operation on top of 1295 * swap_pager_getpages(). 1296 */ 1297 static int 1298 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1299 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1300 { 1301 int r, error; 1302 1303 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1304 VM_OBJECT_WUNLOCK(object); 1305 switch (r) { 1306 case VM_PAGER_OK: 1307 error = 0; 1308 break; 1309 case VM_PAGER_ERROR: 1310 error = EIO; 1311 break; 1312 case VM_PAGER_FAIL: 1313 error = EINVAL; 1314 break; 1315 default: 1316 panic("unhandled swap_pager_getpages() error %d", r); 1317 } 1318 (iodone)(arg, ma, count, error); 1319 VM_OBJECT_WLOCK(object); 1320 1321 return (r); 1322 } 1323 1324 /* 1325 * swap_pager_putpages: 1326 * 1327 * Assign swap (if necessary) and initiate I/O on the specified pages. 1328 * 1329 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1330 * are automatically converted to SWAP objects. 1331 * 1332 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1333 * vm_page reservation system coupled with properly written VFS devices 1334 * should ensure that no low-memory deadlock occurs. This is an area 1335 * which needs work. 1336 * 1337 * The parent has N vm_object_pip_add() references prior to 1338 * calling us and will remove references for rtvals[] that are 1339 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1340 * completion. 1341 * 1342 * The parent has soft-busy'd the pages it passes us and will unbusy 1343 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1344 * We need to unbusy the rest on I/O completion. 1345 */ 1346 static void 1347 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1348 int flags, int *rtvals) 1349 { 1350 struct buf *bp; 1351 daddr_t addr, blk, n_free, s_free; 1352 vm_page_t mreq; 1353 int i, j, n; 1354 bool async; 1355 1356 KASSERT(count == 0 || ma[0]->object == object, 1357 ("%s: object mismatch %p/%p", 1358 __func__, object, ma[0]->object)); 1359 1360 /* 1361 * Step 1 1362 * 1363 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1364 */ 1365 if (object->type != OBJT_SWAP) { 1366 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1367 KASSERT(addr == SWAPBLK_NONE, 1368 ("unexpected object swap block")); 1369 } 1370 VM_OBJECT_WUNLOCK(object); 1371 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1372 swp_pager_init_freerange(&s_free, &n_free); 1373 1374 /* 1375 * Step 2 1376 * 1377 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1378 * The page is left dirty until the pageout operation completes 1379 * successfully. 1380 */ 1381 for (i = 0; i < count; i += n) { 1382 /* Maximum I/O size is limited by maximum swap block size. */ 1383 n = min(count - i, nsw_cluster_max); 1384 1385 /* Get a block of swap of size up to size n. */ 1386 blk = swp_pager_getswapspace(&n, 4); 1387 if (blk == SWAPBLK_NONE) { 1388 for (j = 0; j < n; ++j) 1389 rtvals[i + j] = VM_PAGER_FAIL; 1390 continue; 1391 } 1392 1393 /* 1394 * All I/O parameters have been satisfied. Build the I/O 1395 * request and assign the swap space. 1396 */ 1397 if (async) { 1398 mtx_lock(&swbuf_mtx); 1399 while (nsw_wcount_async == 0) 1400 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1401 "swbufa", 0); 1402 nsw_wcount_async--; 1403 mtx_unlock(&swbuf_mtx); 1404 } 1405 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1406 if (async) 1407 bp->b_flags = B_ASYNC; 1408 bp->b_flags |= B_PAGING; 1409 bp->b_iocmd = BIO_WRITE; 1410 1411 bp->b_rcred = crhold(thread0.td_ucred); 1412 bp->b_wcred = crhold(thread0.td_ucred); 1413 bp->b_bcount = PAGE_SIZE * n; 1414 bp->b_bufsize = PAGE_SIZE * n; 1415 bp->b_blkno = blk; 1416 1417 VM_OBJECT_WLOCK(object); 1418 for (j = 0; j < n; ++j) { 1419 mreq = ma[i + j]; 1420 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1421 blk + j); 1422 if (addr != SWAPBLK_NONE) 1423 swp_pager_update_freerange(&s_free, &n_free, 1424 addr); 1425 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1426 mreq->oflags |= VPO_SWAPINPROG; 1427 bp->b_pages[j] = mreq; 1428 } 1429 VM_OBJECT_WUNLOCK(object); 1430 bp->b_npages = n; 1431 /* 1432 * Must set dirty range for NFS to work. 1433 */ 1434 bp->b_dirtyoff = 0; 1435 bp->b_dirtyend = bp->b_bcount; 1436 1437 VM_CNT_INC(v_swapout); 1438 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1439 1440 /* 1441 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1442 * can call the async completion routine at the end of a 1443 * synchronous I/O operation. Otherwise, our caller would 1444 * perform duplicate unbusy and wakeup operations on the page 1445 * and object, respectively. 1446 */ 1447 for (j = 0; j < n; j++) 1448 rtvals[i + j] = VM_PAGER_PEND; 1449 1450 /* 1451 * asynchronous 1452 * 1453 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1454 */ 1455 if (async) { 1456 bp->b_iodone = swp_pager_async_iodone; 1457 BUF_KERNPROC(bp); 1458 swp_pager_strategy(bp); 1459 continue; 1460 } 1461 1462 /* 1463 * synchronous 1464 * 1465 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1466 */ 1467 bp->b_iodone = bdone; 1468 swp_pager_strategy(bp); 1469 1470 /* 1471 * Wait for the sync I/O to complete. 1472 */ 1473 bwait(bp, PVM, "swwrt"); 1474 1475 /* 1476 * Now that we are through with the bp, we can call the 1477 * normal async completion, which frees everything up. 1478 */ 1479 swp_pager_async_iodone(bp); 1480 } 1481 swp_pager_freeswapspace(s_free, n_free); 1482 VM_OBJECT_WLOCK(object); 1483 } 1484 1485 /* 1486 * swp_pager_async_iodone: 1487 * 1488 * Completion routine for asynchronous reads and writes from/to swap. 1489 * Also called manually by synchronous code to finish up a bp. 1490 * 1491 * This routine may not sleep. 1492 */ 1493 static void 1494 swp_pager_async_iodone(struct buf *bp) 1495 { 1496 int i; 1497 vm_object_t object = NULL; 1498 1499 /* 1500 * Report error - unless we ran out of memory, in which case 1501 * we've already logged it in swapgeom_strategy(). 1502 */ 1503 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1504 printf( 1505 "swap_pager: I/O error - %s failed; blkno %ld," 1506 "size %ld, error %d\n", 1507 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1508 (long)bp->b_blkno, 1509 (long)bp->b_bcount, 1510 bp->b_error 1511 ); 1512 } 1513 1514 /* 1515 * remove the mapping for kernel virtual 1516 */ 1517 if (buf_mapped(bp)) 1518 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1519 else 1520 bp->b_data = bp->b_kvabase; 1521 1522 if (bp->b_npages) { 1523 object = bp->b_pages[0]->object; 1524 VM_OBJECT_WLOCK(object); 1525 } 1526 1527 /* 1528 * cleanup pages. If an error occurs writing to swap, we are in 1529 * very serious trouble. If it happens to be a disk error, though, 1530 * we may be able to recover by reassigning the swap later on. So 1531 * in this case we remove the m->swapblk assignment for the page 1532 * but do not free it in the rlist. The errornous block(s) are thus 1533 * never reallocated as swap. Redirty the page and continue. 1534 */ 1535 for (i = 0; i < bp->b_npages; ++i) { 1536 vm_page_t m = bp->b_pages[i]; 1537 1538 m->oflags &= ~VPO_SWAPINPROG; 1539 if (m->oflags & VPO_SWAPSLEEP) { 1540 m->oflags &= ~VPO_SWAPSLEEP; 1541 wakeup(&object->handle); 1542 } 1543 1544 if (bp->b_ioflags & BIO_ERROR) { 1545 /* 1546 * If an error occurs I'd love to throw the swapblk 1547 * away without freeing it back to swapspace, so it 1548 * can never be used again. But I can't from an 1549 * interrupt. 1550 */ 1551 if (bp->b_iocmd == BIO_READ) { 1552 /* 1553 * NOTE: for reads, m->dirty will probably 1554 * be overridden by the original caller of 1555 * getpages so don't play cute tricks here. 1556 */ 1557 m->valid = 0; 1558 } else { 1559 /* 1560 * If a write error occurs, reactivate page 1561 * so it doesn't clog the inactive list, 1562 * then finish the I/O. 1563 */ 1564 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1565 vm_page_lock(m); 1566 vm_page_activate(m); 1567 vm_page_unlock(m); 1568 vm_page_sunbusy(m); 1569 } 1570 } else if (bp->b_iocmd == BIO_READ) { 1571 /* 1572 * NOTE: for reads, m->dirty will probably be 1573 * overridden by the original caller of getpages so 1574 * we cannot set them in order to free the underlying 1575 * swap in a low-swap situation. I don't think we'd 1576 * want to do that anyway, but it was an optimization 1577 * that existed in the old swapper for a time before 1578 * it got ripped out due to precisely this problem. 1579 */ 1580 KASSERT(!pmap_page_is_mapped(m), 1581 ("swp_pager_async_iodone: page %p is mapped", m)); 1582 KASSERT(m->dirty == 0, 1583 ("swp_pager_async_iodone: page %p is dirty", m)); 1584 1585 m->valid = VM_PAGE_BITS_ALL; 1586 if (i < bp->b_pgbefore || 1587 i >= bp->b_npages - bp->b_pgafter) 1588 vm_page_readahead_finish(m); 1589 } else { 1590 /* 1591 * For write success, clear the dirty 1592 * status, then finish the I/O ( which decrements the 1593 * busy count and possibly wakes waiter's up ). 1594 * A page is only written to swap after a period of 1595 * inactivity. Therefore, we do not expect it to be 1596 * reused. 1597 */ 1598 KASSERT(!pmap_page_is_write_mapped(m), 1599 ("swp_pager_async_iodone: page %p is not write" 1600 " protected", m)); 1601 vm_page_undirty(m); 1602 vm_page_lock(m); 1603 vm_page_deactivate_noreuse(m); 1604 vm_page_unlock(m); 1605 vm_page_sunbusy(m); 1606 } 1607 } 1608 1609 /* 1610 * adjust pip. NOTE: the original parent may still have its own 1611 * pip refs on the object. 1612 */ 1613 if (object != NULL) { 1614 vm_object_pip_wakeupn(object, bp->b_npages); 1615 VM_OBJECT_WUNLOCK(object); 1616 } 1617 1618 /* 1619 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1620 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1621 * trigger a KASSERT in relpbuf(). 1622 */ 1623 if (bp->b_vp) { 1624 bp->b_vp = NULL; 1625 bp->b_bufobj = NULL; 1626 } 1627 /* 1628 * release the physical I/O buffer 1629 */ 1630 if (bp->b_flags & B_ASYNC) { 1631 mtx_lock(&swbuf_mtx); 1632 if (++nsw_wcount_async == 1) 1633 wakeup(&nsw_wcount_async); 1634 mtx_unlock(&swbuf_mtx); 1635 } 1636 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1637 } 1638 1639 int 1640 swap_pager_nswapdev(void) 1641 { 1642 1643 return (nswapdev); 1644 } 1645 1646 static void 1647 swp_pager_force_dirty(vm_page_t m) 1648 { 1649 1650 vm_page_dirty(m); 1651 #ifdef INVARIANTS 1652 vm_page_lock(m); 1653 if (!vm_page_wired(m) && m->queue == PQ_NONE) 1654 panic("page %p is neither wired nor queued", m); 1655 vm_page_unlock(m); 1656 #endif 1657 vm_page_xunbusy(m); 1658 swap_pager_unswapped(m); 1659 } 1660 1661 static void 1662 swp_pager_force_launder(vm_page_t m) 1663 { 1664 1665 vm_page_dirty(m); 1666 vm_page_lock(m); 1667 vm_page_launder(m); 1668 vm_page_unlock(m); 1669 vm_page_xunbusy(m); 1670 swap_pager_unswapped(m); 1671 } 1672 1673 /* 1674 * SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in 1675 * 1676 * This routine dissociates pages starting at the given index within an 1677 * object from their backing store, paging them in if they do not reside 1678 * in memory. Pages that are paged in are marked dirty and placed in the 1679 * laundry queue. Pages are marked dirty because they no longer have 1680 * backing store. They are placed in the laundry queue because they have 1681 * not been accessed recently. Otherwise, they would already reside in 1682 * memory. 1683 */ 1684 static void 1685 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages) 1686 { 1687 vm_page_t ma[npages]; 1688 int i, j; 1689 1690 KASSERT(npages > 0, ("%s: No pages", __func__)); 1691 KASSERT(npages <= MAXPHYS / PAGE_SIZE, 1692 ("%s: Too many pages: %d", __func__, npages)); 1693 vm_object_pip_add(object, npages); 1694 vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages); 1695 for (i = j = 0;; i++) { 1696 /* Count nonresident pages, to page-in all at once. */ 1697 if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL) 1698 continue; 1699 if (j < i) { 1700 /* Page-in nonresident pages. Mark for laundering. */ 1701 if (swap_pager_getpages(object, &ma[j], i - j, NULL, 1702 NULL) != VM_PAGER_OK) 1703 panic("%s: read from swap failed", __func__); 1704 do { 1705 swp_pager_force_launder(ma[j]); 1706 } while (++j < i); 1707 } 1708 if (i == npages) 1709 break; 1710 /* Mark dirty a resident page. */ 1711 swp_pager_force_dirty(ma[j++]); 1712 } 1713 vm_object_pip_wakeupn(object, npages); 1714 } 1715 1716 /* 1717 * swap_pager_swapoff_object: 1718 * 1719 * Page in all of the pages that have been paged out for an object 1720 * to a swap device. 1721 */ 1722 static void 1723 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1724 { 1725 struct swblk *sb; 1726 vm_pindex_t pi, s_pindex; 1727 daddr_t blk, n_blks, s_blk; 1728 int i; 1729 1730 n_blks = 0; 1731 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1732 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1733 for (i = 0; i < SWAP_META_PAGES; i++) { 1734 blk = sb->d[i]; 1735 if (!swp_pager_isondev(blk, sp)) 1736 blk = SWAPBLK_NONE; 1737 1738 /* 1739 * If there are no blocks/pages accumulated, start a new 1740 * accumulation here. 1741 */ 1742 if (n_blks == 0) { 1743 if (blk != SWAPBLK_NONE) { 1744 s_blk = blk; 1745 s_pindex = sb->p + i; 1746 n_blks = 1; 1747 } 1748 continue; 1749 } 1750 1751 /* 1752 * If the accumulation can be extended without breaking 1753 * the sequence of consecutive blocks and pages that 1754 * swp_pager_force_pagein() depends on, do so. 1755 */ 1756 if (n_blks < MAXPHYS / PAGE_SIZE && 1757 s_blk + n_blks == blk && 1758 s_pindex + n_blks == sb->p + i) { 1759 ++n_blks; 1760 continue; 1761 } 1762 1763 /* 1764 * The sequence of consecutive blocks and pages cannot 1765 * be extended, so page them all in here. Then, 1766 * because doing so involves releasing and reacquiring 1767 * a lock that protects the swap block pctrie, do not 1768 * rely on the current swap block. Break this loop and 1769 * re-fetch the same pindex from the pctrie again. 1770 */ 1771 swp_pager_force_pagein(object, s_pindex, n_blks); 1772 n_blks = 0; 1773 break; 1774 } 1775 if (i == SWAP_META_PAGES) 1776 pi = sb->p + SWAP_META_PAGES; 1777 } 1778 if (n_blks > 0) 1779 swp_pager_force_pagein(object, s_pindex, n_blks); 1780 } 1781 1782 /* 1783 * swap_pager_swapoff: 1784 * 1785 * Page in all of the pages that have been paged out to the 1786 * given device. The corresponding blocks in the bitmap must be 1787 * marked as allocated and the device must be flagged SW_CLOSING. 1788 * There may be no processes swapped out to the device. 1789 * 1790 * This routine may block. 1791 */ 1792 static void 1793 swap_pager_swapoff(struct swdevt *sp) 1794 { 1795 vm_object_t object; 1796 int retries; 1797 1798 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1799 1800 retries = 0; 1801 full_rescan: 1802 mtx_lock(&vm_object_list_mtx); 1803 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1804 if (object->type != OBJT_SWAP) 1805 continue; 1806 mtx_unlock(&vm_object_list_mtx); 1807 /* Depends on type-stability. */ 1808 VM_OBJECT_WLOCK(object); 1809 1810 /* 1811 * Dead objects are eventually terminated on their own. 1812 */ 1813 if ((object->flags & OBJ_DEAD) != 0) 1814 goto next_obj; 1815 1816 /* 1817 * Sync with fences placed after pctrie 1818 * initialization. We must not access pctrie below 1819 * unless we checked that our object is swap and not 1820 * dead. 1821 */ 1822 atomic_thread_fence_acq(); 1823 if (object->type != OBJT_SWAP) 1824 goto next_obj; 1825 1826 swap_pager_swapoff_object(sp, object); 1827 next_obj: 1828 VM_OBJECT_WUNLOCK(object); 1829 mtx_lock(&vm_object_list_mtx); 1830 } 1831 mtx_unlock(&vm_object_list_mtx); 1832 1833 if (sp->sw_used) { 1834 /* 1835 * Objects may be locked or paging to the device being 1836 * removed, so we will miss their pages and need to 1837 * make another pass. We have marked this device as 1838 * SW_CLOSING, so the activity should finish soon. 1839 */ 1840 retries++; 1841 if (retries > 100) { 1842 panic("swapoff: failed to locate %d swap blocks", 1843 sp->sw_used); 1844 } 1845 pause("swpoff", hz / 20); 1846 goto full_rescan; 1847 } 1848 EVENTHANDLER_INVOKE(swapoff, sp); 1849 } 1850 1851 /************************************************************************ 1852 * SWAP META DATA * 1853 ************************************************************************ 1854 * 1855 * These routines manipulate the swap metadata stored in the 1856 * OBJT_SWAP object. 1857 * 1858 * Swap metadata is implemented with a global hash and not directly 1859 * linked into the object. Instead the object simply contains 1860 * appropriate tracking counters. 1861 */ 1862 1863 /* 1864 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1865 */ 1866 static bool 1867 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1868 { 1869 int i; 1870 1871 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1872 for (i = start; i < limit; i++) { 1873 if (sb->d[i] != SWAPBLK_NONE) 1874 return (false); 1875 } 1876 return (true); 1877 } 1878 1879 /* 1880 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1881 * 1882 * We first convert the object to a swap object if it is a default 1883 * object. 1884 * 1885 * The specified swapblk is added to the object's swap metadata. If 1886 * the swapblk is not valid, it is freed instead. Any previously 1887 * assigned swapblk is returned. 1888 */ 1889 static daddr_t 1890 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1891 { 1892 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1893 struct swblk *sb, *sb1; 1894 vm_pindex_t modpi, rdpi; 1895 daddr_t prev_swapblk; 1896 int error, i; 1897 1898 VM_OBJECT_ASSERT_WLOCKED(object); 1899 1900 /* 1901 * Convert default object to swap object if necessary 1902 */ 1903 if (object->type != OBJT_SWAP) { 1904 pctrie_init(&object->un_pager.swp.swp_blks); 1905 1906 /* 1907 * Ensure that swap_pager_swapoff()'s iteration over 1908 * object_list does not see a garbage pctrie. 1909 */ 1910 atomic_thread_fence_rel(); 1911 1912 object->type = OBJT_SWAP; 1913 object->un_pager.swp.writemappings = 0; 1914 KASSERT(object->handle == NULL, ("default pager with handle")); 1915 } 1916 1917 rdpi = rounddown(pindex, SWAP_META_PAGES); 1918 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1919 if (sb == NULL) { 1920 if (swapblk == SWAPBLK_NONE) 1921 return (SWAPBLK_NONE); 1922 for (;;) { 1923 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1924 pageproc ? M_USE_RESERVE : 0)); 1925 if (sb != NULL) { 1926 sb->p = rdpi; 1927 for (i = 0; i < SWAP_META_PAGES; i++) 1928 sb->d[i] = SWAPBLK_NONE; 1929 if (atomic_cmpset_int(&swblk_zone_exhausted, 1930 1, 0)) 1931 printf("swblk zone ok\n"); 1932 break; 1933 } 1934 VM_OBJECT_WUNLOCK(object); 1935 if (uma_zone_exhausted(swblk_zone)) { 1936 if (atomic_cmpset_int(&swblk_zone_exhausted, 1937 0, 1)) 1938 printf("swap blk zone exhausted, " 1939 "increase kern.maxswzone\n"); 1940 vm_pageout_oom(VM_OOM_SWAPZ); 1941 pause("swzonxb", 10); 1942 } else 1943 uma_zwait(swblk_zone); 1944 VM_OBJECT_WLOCK(object); 1945 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1946 rdpi); 1947 if (sb != NULL) 1948 /* 1949 * Somebody swapped out a nearby page, 1950 * allocating swblk at the rdpi index, 1951 * while we dropped the object lock. 1952 */ 1953 goto allocated; 1954 } 1955 for (;;) { 1956 error = SWAP_PCTRIE_INSERT( 1957 &object->un_pager.swp.swp_blks, sb); 1958 if (error == 0) { 1959 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1960 1, 0)) 1961 printf("swpctrie zone ok\n"); 1962 break; 1963 } 1964 VM_OBJECT_WUNLOCK(object); 1965 if (uma_zone_exhausted(swpctrie_zone)) { 1966 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1967 0, 1)) 1968 printf("swap pctrie zone exhausted, " 1969 "increase kern.maxswzone\n"); 1970 vm_pageout_oom(VM_OOM_SWAPZ); 1971 pause("swzonxp", 10); 1972 } else 1973 uma_zwait(swpctrie_zone); 1974 VM_OBJECT_WLOCK(object); 1975 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1976 rdpi); 1977 if (sb1 != NULL) { 1978 uma_zfree(swblk_zone, sb); 1979 sb = sb1; 1980 goto allocated; 1981 } 1982 } 1983 } 1984 allocated: 1985 MPASS(sb->p == rdpi); 1986 1987 modpi = pindex % SWAP_META_PAGES; 1988 /* Return prior contents of metadata. */ 1989 prev_swapblk = sb->d[modpi]; 1990 /* Enter block into metadata. */ 1991 sb->d[modpi] = swapblk; 1992 1993 /* 1994 * Free the swblk if we end up with the empty page run. 1995 */ 1996 if (swapblk == SWAPBLK_NONE && 1997 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1998 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 1999 uma_zfree(swblk_zone, sb); 2000 } 2001 return (prev_swapblk); 2002 } 2003 2004 /* 2005 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2006 * 2007 * The requested range of blocks is freed, with any associated swap 2008 * returned to the swap bitmap. 2009 * 2010 * This routine will free swap metadata structures as they are cleaned 2011 * out. This routine does *NOT* operate on swap metadata associated 2012 * with resident pages. 2013 */ 2014 static void 2015 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2016 { 2017 struct swblk *sb; 2018 daddr_t n_free, s_free; 2019 vm_pindex_t last; 2020 int i, limit, start; 2021 2022 VM_OBJECT_ASSERT_WLOCKED(object); 2023 if (object->type != OBJT_SWAP || count == 0) 2024 return; 2025 2026 swp_pager_init_freerange(&s_free, &n_free); 2027 last = pindex + count; 2028 for (;;) { 2029 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2030 rounddown(pindex, SWAP_META_PAGES)); 2031 if (sb == NULL || sb->p >= last) 2032 break; 2033 start = pindex > sb->p ? pindex - sb->p : 0; 2034 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2035 SWAP_META_PAGES; 2036 for (i = start; i < limit; i++) { 2037 if (sb->d[i] == SWAPBLK_NONE) 2038 continue; 2039 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2040 sb->d[i] = SWAPBLK_NONE; 2041 } 2042 pindex = sb->p + SWAP_META_PAGES; 2043 if (swp_pager_swblk_empty(sb, 0, start) && 2044 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2045 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2046 sb->p); 2047 uma_zfree(swblk_zone, sb); 2048 } 2049 } 2050 swp_pager_freeswapspace(s_free, n_free); 2051 } 2052 2053 /* 2054 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2055 * 2056 * This routine locates and destroys all swap metadata associated with 2057 * an object. 2058 */ 2059 static void 2060 swp_pager_meta_free_all(vm_object_t object) 2061 { 2062 struct swblk *sb; 2063 daddr_t n_free, s_free; 2064 vm_pindex_t pindex; 2065 int i; 2066 2067 VM_OBJECT_ASSERT_WLOCKED(object); 2068 if (object->type != OBJT_SWAP) 2069 return; 2070 2071 swp_pager_init_freerange(&s_free, &n_free); 2072 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2073 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2074 pindex = sb->p + SWAP_META_PAGES; 2075 for (i = 0; i < SWAP_META_PAGES; i++) { 2076 if (sb->d[i] == SWAPBLK_NONE) 2077 continue; 2078 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2079 } 2080 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2081 uma_zfree(swblk_zone, sb); 2082 } 2083 swp_pager_freeswapspace(s_free, n_free); 2084 } 2085 2086 /* 2087 * SWP_PAGER_METACTL() - misc control of swap meta data. 2088 * 2089 * This routine is capable of looking up, or removing swapblk 2090 * assignments in the swap meta data. It returns the swapblk being 2091 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2092 * 2093 * When acting on a busy resident page and paging is in progress, we 2094 * have to wait until paging is complete but otherwise can act on the 2095 * busy page. 2096 * 2097 * SWM_POP remove from meta data but do not free it 2098 */ 2099 static daddr_t 2100 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2101 { 2102 struct swblk *sb; 2103 daddr_t r1; 2104 2105 if ((flags & SWM_POP) != 0) 2106 VM_OBJECT_ASSERT_WLOCKED(object); 2107 else 2108 VM_OBJECT_ASSERT_LOCKED(object); 2109 2110 /* 2111 * The meta data only exists if the object is OBJT_SWAP 2112 * and even then might not be allocated yet. 2113 */ 2114 if (object->type != OBJT_SWAP) 2115 return (SWAPBLK_NONE); 2116 2117 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2118 rounddown(pindex, SWAP_META_PAGES)); 2119 if (sb == NULL) 2120 return (SWAPBLK_NONE); 2121 r1 = sb->d[pindex % SWAP_META_PAGES]; 2122 if (r1 == SWAPBLK_NONE) 2123 return (SWAPBLK_NONE); 2124 if ((flags & SWM_POP) != 0) { 2125 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2126 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2127 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2128 rounddown(pindex, SWAP_META_PAGES)); 2129 uma_zfree(swblk_zone, sb); 2130 } 2131 } 2132 return (r1); 2133 } 2134 2135 /* 2136 * Returns the least page index which is greater than or equal to the 2137 * parameter pindex and for which there is a swap block allocated. 2138 * Returns object's size if the object's type is not swap or if there 2139 * are no allocated swap blocks for the object after the requested 2140 * pindex. 2141 */ 2142 vm_pindex_t 2143 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2144 { 2145 struct swblk *sb; 2146 int i; 2147 2148 VM_OBJECT_ASSERT_LOCKED(object); 2149 if (object->type != OBJT_SWAP) 2150 return (object->size); 2151 2152 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2153 rounddown(pindex, SWAP_META_PAGES)); 2154 if (sb == NULL) 2155 return (object->size); 2156 if (sb->p < pindex) { 2157 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2158 if (sb->d[i] != SWAPBLK_NONE) 2159 return (sb->p + i); 2160 } 2161 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2162 roundup(pindex, SWAP_META_PAGES)); 2163 if (sb == NULL) 2164 return (object->size); 2165 } 2166 for (i = 0; i < SWAP_META_PAGES; i++) { 2167 if (sb->d[i] != SWAPBLK_NONE) 2168 return (sb->p + i); 2169 } 2170 2171 /* 2172 * We get here if a swblk is present in the trie but it 2173 * doesn't map any blocks. 2174 */ 2175 MPASS(0); 2176 return (object->size); 2177 } 2178 2179 /* 2180 * System call swapon(name) enables swapping on device name, 2181 * which must be in the swdevsw. Return EBUSY 2182 * if already swapping on this device. 2183 */ 2184 #ifndef _SYS_SYSPROTO_H_ 2185 struct swapon_args { 2186 char *name; 2187 }; 2188 #endif 2189 2190 /* 2191 * MPSAFE 2192 */ 2193 /* ARGSUSED */ 2194 int 2195 sys_swapon(struct thread *td, struct swapon_args *uap) 2196 { 2197 struct vattr attr; 2198 struct vnode *vp; 2199 struct nameidata nd; 2200 int error; 2201 2202 error = priv_check(td, PRIV_SWAPON); 2203 if (error) 2204 return (error); 2205 2206 sx_xlock(&swdev_syscall_lock); 2207 2208 /* 2209 * Swap metadata may not fit in the KVM if we have physical 2210 * memory of >1GB. 2211 */ 2212 if (swblk_zone == NULL) { 2213 error = ENOMEM; 2214 goto done; 2215 } 2216 2217 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2218 uap->name, td); 2219 error = namei(&nd); 2220 if (error) 2221 goto done; 2222 2223 NDFREE(&nd, NDF_ONLY_PNBUF); 2224 vp = nd.ni_vp; 2225 2226 if (vn_isdisk(vp, &error)) { 2227 error = swapongeom(vp); 2228 } else if (vp->v_type == VREG && 2229 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2230 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2231 /* 2232 * Allow direct swapping to NFS regular files in the same 2233 * way that nfs_mountroot() sets up diskless swapping. 2234 */ 2235 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2236 } 2237 2238 if (error) 2239 vrele(vp); 2240 done: 2241 sx_xunlock(&swdev_syscall_lock); 2242 return (error); 2243 } 2244 2245 /* 2246 * Check that the total amount of swap currently configured does not 2247 * exceed half the theoretical maximum. If it does, print a warning 2248 * message. 2249 */ 2250 static void 2251 swapon_check_swzone(void) 2252 { 2253 unsigned long maxpages, npages; 2254 2255 npages = swap_total; 2256 /* absolute maximum we can handle assuming 100% efficiency */ 2257 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2258 2259 /* recommend using no more than half that amount */ 2260 if (npages > maxpages / 2) { 2261 printf("warning: total configured swap (%lu pages) " 2262 "exceeds maximum recommended amount (%lu pages).\n", 2263 npages, maxpages / 2); 2264 printf("warning: increase kern.maxswzone " 2265 "or reduce amount of swap.\n"); 2266 } 2267 } 2268 2269 static void 2270 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2271 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2272 { 2273 struct swdevt *sp, *tsp; 2274 swblk_t dvbase; 2275 u_long mblocks; 2276 2277 /* 2278 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2279 * First chop nblks off to page-align it, then convert. 2280 * 2281 * sw->sw_nblks is in page-sized chunks now too. 2282 */ 2283 nblks &= ~(ctodb(1) - 1); 2284 nblks = dbtoc(nblks); 2285 2286 /* 2287 * If we go beyond this, we get overflows in the radix 2288 * tree bitmap code. 2289 */ 2290 mblocks = 0x40000000 / BLIST_META_RADIX; 2291 if (nblks > mblocks) { 2292 printf( 2293 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2294 mblocks / 1024 / 1024 * PAGE_SIZE); 2295 nblks = mblocks; 2296 } 2297 2298 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2299 sp->sw_vp = vp; 2300 sp->sw_id = id; 2301 sp->sw_dev = dev; 2302 sp->sw_nblks = nblks; 2303 sp->sw_used = 0; 2304 sp->sw_strategy = strategy; 2305 sp->sw_close = close; 2306 sp->sw_flags = flags; 2307 2308 sp->sw_blist = blist_create(nblks, M_WAITOK); 2309 /* 2310 * Do not free the first blocks in order to avoid overwriting 2311 * any bsd label at the front of the partition 2312 */ 2313 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2314 nblks - howmany(BBSIZE, PAGE_SIZE)); 2315 2316 dvbase = 0; 2317 mtx_lock(&sw_dev_mtx); 2318 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2319 if (tsp->sw_end >= dvbase) { 2320 /* 2321 * We put one uncovered page between the devices 2322 * in order to definitively prevent any cross-device 2323 * I/O requests 2324 */ 2325 dvbase = tsp->sw_end + 1; 2326 } 2327 } 2328 sp->sw_first = dvbase; 2329 sp->sw_end = dvbase + nblks; 2330 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2331 nswapdev++; 2332 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2333 swap_total += nblks; 2334 swapon_check_swzone(); 2335 swp_sizecheck(); 2336 mtx_unlock(&sw_dev_mtx); 2337 EVENTHANDLER_INVOKE(swapon, sp); 2338 } 2339 2340 /* 2341 * SYSCALL: swapoff(devname) 2342 * 2343 * Disable swapping on the given device. 2344 * 2345 * XXX: Badly designed system call: it should use a device index 2346 * rather than filename as specification. We keep sw_vp around 2347 * only to make this work. 2348 */ 2349 #ifndef _SYS_SYSPROTO_H_ 2350 struct swapoff_args { 2351 char *name; 2352 }; 2353 #endif 2354 2355 /* 2356 * MPSAFE 2357 */ 2358 /* ARGSUSED */ 2359 int 2360 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2361 { 2362 struct vnode *vp; 2363 struct nameidata nd; 2364 struct swdevt *sp; 2365 int error; 2366 2367 error = priv_check(td, PRIV_SWAPOFF); 2368 if (error) 2369 return (error); 2370 2371 sx_xlock(&swdev_syscall_lock); 2372 2373 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2374 td); 2375 error = namei(&nd); 2376 if (error) 2377 goto done; 2378 NDFREE(&nd, NDF_ONLY_PNBUF); 2379 vp = nd.ni_vp; 2380 2381 mtx_lock(&sw_dev_mtx); 2382 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2383 if (sp->sw_vp == vp) 2384 break; 2385 } 2386 mtx_unlock(&sw_dev_mtx); 2387 if (sp == NULL) { 2388 error = EINVAL; 2389 goto done; 2390 } 2391 error = swapoff_one(sp, td->td_ucred); 2392 done: 2393 sx_xunlock(&swdev_syscall_lock); 2394 return (error); 2395 } 2396 2397 static int 2398 swapoff_one(struct swdevt *sp, struct ucred *cred) 2399 { 2400 u_long nblks; 2401 #ifdef MAC 2402 int error; 2403 #endif 2404 2405 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2406 #ifdef MAC 2407 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2408 error = mac_system_check_swapoff(cred, sp->sw_vp); 2409 (void) VOP_UNLOCK(sp->sw_vp, 0); 2410 if (error != 0) 2411 return (error); 2412 #endif 2413 nblks = sp->sw_nblks; 2414 2415 /* 2416 * We can turn off this swap device safely only if the 2417 * available virtual memory in the system will fit the amount 2418 * of data we will have to page back in, plus an epsilon so 2419 * the system doesn't become critically low on swap space. 2420 */ 2421 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2422 return (ENOMEM); 2423 2424 /* 2425 * Prevent further allocations on this device. 2426 */ 2427 mtx_lock(&sw_dev_mtx); 2428 sp->sw_flags |= SW_CLOSING; 2429 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2430 swap_total -= nblks; 2431 mtx_unlock(&sw_dev_mtx); 2432 2433 /* 2434 * Page in the contents of the device and close it. 2435 */ 2436 swap_pager_swapoff(sp); 2437 2438 sp->sw_close(curthread, sp); 2439 mtx_lock(&sw_dev_mtx); 2440 sp->sw_id = NULL; 2441 TAILQ_REMOVE(&swtailq, sp, sw_list); 2442 nswapdev--; 2443 if (nswapdev == 0) { 2444 swap_pager_full = 2; 2445 swap_pager_almost_full = 1; 2446 } 2447 if (swdevhd == sp) 2448 swdevhd = NULL; 2449 mtx_unlock(&sw_dev_mtx); 2450 blist_destroy(sp->sw_blist); 2451 free(sp, M_VMPGDATA); 2452 return (0); 2453 } 2454 2455 void 2456 swapoff_all(void) 2457 { 2458 struct swdevt *sp, *spt; 2459 const char *devname; 2460 int error; 2461 2462 sx_xlock(&swdev_syscall_lock); 2463 2464 mtx_lock(&sw_dev_mtx); 2465 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2466 mtx_unlock(&sw_dev_mtx); 2467 if (vn_isdisk(sp->sw_vp, NULL)) 2468 devname = devtoname(sp->sw_vp->v_rdev); 2469 else 2470 devname = "[file]"; 2471 error = swapoff_one(sp, thread0.td_ucred); 2472 if (error != 0) { 2473 printf("Cannot remove swap device %s (error=%d), " 2474 "skipping.\n", devname, error); 2475 } else if (bootverbose) { 2476 printf("Swap device %s removed.\n", devname); 2477 } 2478 mtx_lock(&sw_dev_mtx); 2479 } 2480 mtx_unlock(&sw_dev_mtx); 2481 2482 sx_xunlock(&swdev_syscall_lock); 2483 } 2484 2485 void 2486 swap_pager_status(int *total, int *used) 2487 { 2488 struct swdevt *sp; 2489 2490 *total = 0; 2491 *used = 0; 2492 mtx_lock(&sw_dev_mtx); 2493 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2494 *total += sp->sw_nblks; 2495 *used += sp->sw_used; 2496 } 2497 mtx_unlock(&sw_dev_mtx); 2498 } 2499 2500 int 2501 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2502 { 2503 struct swdevt *sp; 2504 const char *tmp_devname; 2505 int error, n; 2506 2507 n = 0; 2508 error = ENOENT; 2509 mtx_lock(&sw_dev_mtx); 2510 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2511 if (n != name) { 2512 n++; 2513 continue; 2514 } 2515 xs->xsw_version = XSWDEV_VERSION; 2516 xs->xsw_dev = sp->sw_dev; 2517 xs->xsw_flags = sp->sw_flags; 2518 xs->xsw_nblks = sp->sw_nblks; 2519 xs->xsw_used = sp->sw_used; 2520 if (devname != NULL) { 2521 if (vn_isdisk(sp->sw_vp, NULL)) 2522 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2523 else 2524 tmp_devname = "[file]"; 2525 strncpy(devname, tmp_devname, len); 2526 } 2527 error = 0; 2528 break; 2529 } 2530 mtx_unlock(&sw_dev_mtx); 2531 return (error); 2532 } 2533 2534 #if defined(COMPAT_FREEBSD11) 2535 #define XSWDEV_VERSION_11 1 2536 struct xswdev11 { 2537 u_int xsw_version; 2538 uint32_t xsw_dev; 2539 int xsw_flags; 2540 int xsw_nblks; 2541 int xsw_used; 2542 }; 2543 #endif 2544 2545 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2546 struct xswdev32 { 2547 u_int xsw_version; 2548 u_int xsw_dev1, xsw_dev2; 2549 int xsw_flags; 2550 int xsw_nblks; 2551 int xsw_used; 2552 }; 2553 #endif 2554 2555 static int 2556 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2557 { 2558 struct xswdev xs; 2559 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2560 struct xswdev32 xs32; 2561 #endif 2562 #if defined(COMPAT_FREEBSD11) 2563 struct xswdev11 xs11; 2564 #endif 2565 int error; 2566 2567 if (arg2 != 1) /* name length */ 2568 return (EINVAL); 2569 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2570 if (error != 0) 2571 return (error); 2572 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2573 if (req->oldlen == sizeof(xs32)) { 2574 xs32.xsw_version = XSWDEV_VERSION; 2575 xs32.xsw_dev1 = xs.xsw_dev; 2576 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2577 xs32.xsw_flags = xs.xsw_flags; 2578 xs32.xsw_nblks = xs.xsw_nblks; 2579 xs32.xsw_used = xs.xsw_used; 2580 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2581 return (error); 2582 } 2583 #endif 2584 #if defined(COMPAT_FREEBSD11) 2585 if (req->oldlen == sizeof(xs11)) { 2586 xs11.xsw_version = XSWDEV_VERSION_11; 2587 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2588 xs11.xsw_flags = xs.xsw_flags; 2589 xs11.xsw_nblks = xs.xsw_nblks; 2590 xs11.xsw_used = xs.xsw_used; 2591 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2592 return (error); 2593 } 2594 #endif 2595 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2596 return (error); 2597 } 2598 2599 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2600 "Number of swap devices"); 2601 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2602 sysctl_vm_swap_info, 2603 "Swap statistics by device"); 2604 2605 /* 2606 * Count the approximate swap usage in pages for a vmspace. The 2607 * shadowed or not yet copied on write swap blocks are not accounted. 2608 * The map must be locked. 2609 */ 2610 long 2611 vmspace_swap_count(struct vmspace *vmspace) 2612 { 2613 vm_map_t map; 2614 vm_map_entry_t cur; 2615 vm_object_t object; 2616 struct swblk *sb; 2617 vm_pindex_t e, pi; 2618 long count; 2619 int i; 2620 2621 map = &vmspace->vm_map; 2622 count = 0; 2623 2624 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2625 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2626 continue; 2627 object = cur->object.vm_object; 2628 if (object == NULL || object->type != OBJT_SWAP) 2629 continue; 2630 VM_OBJECT_RLOCK(object); 2631 if (object->type != OBJT_SWAP) 2632 goto unlock; 2633 pi = OFF_TO_IDX(cur->offset); 2634 e = pi + OFF_TO_IDX(cur->end - cur->start); 2635 for (;; pi = sb->p + SWAP_META_PAGES) { 2636 sb = SWAP_PCTRIE_LOOKUP_GE( 2637 &object->un_pager.swp.swp_blks, pi); 2638 if (sb == NULL || sb->p >= e) 2639 break; 2640 for (i = 0; i < SWAP_META_PAGES; i++) { 2641 if (sb->p + i < e && 2642 sb->d[i] != SWAPBLK_NONE) 2643 count++; 2644 } 2645 } 2646 unlock: 2647 VM_OBJECT_RUNLOCK(object); 2648 } 2649 return (count); 2650 } 2651 2652 /* 2653 * GEOM backend 2654 * 2655 * Swapping onto disk devices. 2656 * 2657 */ 2658 2659 static g_orphan_t swapgeom_orphan; 2660 2661 static struct g_class g_swap_class = { 2662 .name = "SWAP", 2663 .version = G_VERSION, 2664 .orphan = swapgeom_orphan, 2665 }; 2666 2667 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2668 2669 2670 static void 2671 swapgeom_close_ev(void *arg, int flags) 2672 { 2673 struct g_consumer *cp; 2674 2675 cp = arg; 2676 g_access(cp, -1, -1, 0); 2677 g_detach(cp); 2678 g_destroy_consumer(cp); 2679 } 2680 2681 /* 2682 * Add a reference to the g_consumer for an inflight transaction. 2683 */ 2684 static void 2685 swapgeom_acquire(struct g_consumer *cp) 2686 { 2687 2688 mtx_assert(&sw_dev_mtx, MA_OWNED); 2689 cp->index++; 2690 } 2691 2692 /* 2693 * Remove a reference from the g_consumer. Post a close event if all 2694 * references go away, since the function might be called from the 2695 * biodone context. 2696 */ 2697 static void 2698 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2699 { 2700 2701 mtx_assert(&sw_dev_mtx, MA_OWNED); 2702 cp->index--; 2703 if (cp->index == 0) { 2704 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2705 sp->sw_id = NULL; 2706 } 2707 } 2708 2709 static void 2710 swapgeom_done(struct bio *bp2) 2711 { 2712 struct swdevt *sp; 2713 struct buf *bp; 2714 struct g_consumer *cp; 2715 2716 bp = bp2->bio_caller2; 2717 cp = bp2->bio_from; 2718 bp->b_ioflags = bp2->bio_flags; 2719 if (bp2->bio_error) 2720 bp->b_ioflags |= BIO_ERROR; 2721 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2722 bp->b_error = bp2->bio_error; 2723 bp->b_caller1 = NULL; 2724 bufdone(bp); 2725 sp = bp2->bio_caller1; 2726 mtx_lock(&sw_dev_mtx); 2727 swapgeom_release(cp, sp); 2728 mtx_unlock(&sw_dev_mtx); 2729 g_destroy_bio(bp2); 2730 } 2731 2732 static void 2733 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2734 { 2735 struct bio *bio; 2736 struct g_consumer *cp; 2737 2738 mtx_lock(&sw_dev_mtx); 2739 cp = sp->sw_id; 2740 if (cp == NULL) { 2741 mtx_unlock(&sw_dev_mtx); 2742 bp->b_error = ENXIO; 2743 bp->b_ioflags |= BIO_ERROR; 2744 bufdone(bp); 2745 return; 2746 } 2747 swapgeom_acquire(cp); 2748 mtx_unlock(&sw_dev_mtx); 2749 if (bp->b_iocmd == BIO_WRITE) 2750 bio = g_new_bio(); 2751 else 2752 bio = g_alloc_bio(); 2753 if (bio == NULL) { 2754 mtx_lock(&sw_dev_mtx); 2755 swapgeom_release(cp, sp); 2756 mtx_unlock(&sw_dev_mtx); 2757 bp->b_error = ENOMEM; 2758 bp->b_ioflags |= BIO_ERROR; 2759 printf("swap_pager: cannot allocate bio\n"); 2760 bufdone(bp); 2761 return; 2762 } 2763 2764 bp->b_caller1 = bio; 2765 bio->bio_caller1 = sp; 2766 bio->bio_caller2 = bp; 2767 bio->bio_cmd = bp->b_iocmd; 2768 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2769 bio->bio_length = bp->b_bcount; 2770 bio->bio_done = swapgeom_done; 2771 if (!buf_mapped(bp)) { 2772 bio->bio_ma = bp->b_pages; 2773 bio->bio_data = unmapped_buf; 2774 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2775 bio->bio_ma_n = bp->b_npages; 2776 bio->bio_flags |= BIO_UNMAPPED; 2777 } else { 2778 bio->bio_data = bp->b_data; 2779 bio->bio_ma = NULL; 2780 } 2781 g_io_request(bio, cp); 2782 return; 2783 } 2784 2785 static void 2786 swapgeom_orphan(struct g_consumer *cp) 2787 { 2788 struct swdevt *sp; 2789 int destroy; 2790 2791 mtx_lock(&sw_dev_mtx); 2792 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2793 if (sp->sw_id == cp) { 2794 sp->sw_flags |= SW_CLOSING; 2795 break; 2796 } 2797 } 2798 /* 2799 * Drop reference we were created with. Do directly since we're in a 2800 * special context where we don't have to queue the call to 2801 * swapgeom_close_ev(). 2802 */ 2803 cp->index--; 2804 destroy = ((sp != NULL) && (cp->index == 0)); 2805 if (destroy) 2806 sp->sw_id = NULL; 2807 mtx_unlock(&sw_dev_mtx); 2808 if (destroy) 2809 swapgeom_close_ev(cp, 0); 2810 } 2811 2812 static void 2813 swapgeom_close(struct thread *td, struct swdevt *sw) 2814 { 2815 struct g_consumer *cp; 2816 2817 mtx_lock(&sw_dev_mtx); 2818 cp = sw->sw_id; 2819 sw->sw_id = NULL; 2820 mtx_unlock(&sw_dev_mtx); 2821 2822 /* 2823 * swapgeom_close() may be called from the biodone context, 2824 * where we cannot perform topology changes. Delegate the 2825 * work to the events thread. 2826 */ 2827 if (cp != NULL) 2828 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2829 } 2830 2831 static int 2832 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2833 { 2834 struct g_provider *pp; 2835 struct g_consumer *cp; 2836 static struct g_geom *gp; 2837 struct swdevt *sp; 2838 u_long nblks; 2839 int error; 2840 2841 pp = g_dev_getprovider(dev); 2842 if (pp == NULL) 2843 return (ENODEV); 2844 mtx_lock(&sw_dev_mtx); 2845 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2846 cp = sp->sw_id; 2847 if (cp != NULL && cp->provider == pp) { 2848 mtx_unlock(&sw_dev_mtx); 2849 return (EBUSY); 2850 } 2851 } 2852 mtx_unlock(&sw_dev_mtx); 2853 if (gp == NULL) 2854 gp = g_new_geomf(&g_swap_class, "swap"); 2855 cp = g_new_consumer(gp); 2856 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2857 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2858 g_attach(cp, pp); 2859 /* 2860 * XXX: Every time you think you can improve the margin for 2861 * footshooting, somebody depends on the ability to do so: 2862 * savecore(8) wants to write to our swapdev so we cannot 2863 * set an exclusive count :-( 2864 */ 2865 error = g_access(cp, 1, 1, 0); 2866 if (error != 0) { 2867 g_detach(cp); 2868 g_destroy_consumer(cp); 2869 return (error); 2870 } 2871 nblks = pp->mediasize / DEV_BSIZE; 2872 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2873 swapgeom_close, dev2udev(dev), 2874 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2875 return (0); 2876 } 2877 2878 static int 2879 swapongeom(struct vnode *vp) 2880 { 2881 int error; 2882 2883 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2884 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2885 error = ENOENT; 2886 } else { 2887 g_topology_lock(); 2888 error = swapongeom_locked(vp->v_rdev, vp); 2889 g_topology_unlock(); 2890 } 2891 VOP_UNLOCK(vp, 0); 2892 return (error); 2893 } 2894 2895 /* 2896 * VNODE backend 2897 * 2898 * This is used mainly for network filesystem (read: probably only tested 2899 * with NFS) swapfiles. 2900 * 2901 */ 2902 2903 static void 2904 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2905 { 2906 struct vnode *vp2; 2907 2908 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2909 2910 vp2 = sp->sw_id; 2911 vhold(vp2); 2912 if (bp->b_iocmd == BIO_WRITE) { 2913 if (bp->b_bufobj) 2914 bufobj_wdrop(bp->b_bufobj); 2915 bufobj_wref(&vp2->v_bufobj); 2916 } 2917 if (bp->b_bufobj != &vp2->v_bufobj) 2918 bp->b_bufobj = &vp2->v_bufobj; 2919 bp->b_vp = vp2; 2920 bp->b_iooffset = dbtob(bp->b_blkno); 2921 bstrategy(bp); 2922 return; 2923 } 2924 2925 static void 2926 swapdev_close(struct thread *td, struct swdevt *sp) 2927 { 2928 2929 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2930 vrele(sp->sw_vp); 2931 } 2932 2933 2934 static int 2935 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2936 { 2937 struct swdevt *sp; 2938 int error; 2939 2940 if (nblks == 0) 2941 return (ENXIO); 2942 mtx_lock(&sw_dev_mtx); 2943 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2944 if (sp->sw_id == vp) { 2945 mtx_unlock(&sw_dev_mtx); 2946 return (EBUSY); 2947 } 2948 } 2949 mtx_unlock(&sw_dev_mtx); 2950 2951 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2952 #ifdef MAC 2953 error = mac_system_check_swapon(td->td_ucred, vp); 2954 if (error == 0) 2955 #endif 2956 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2957 (void) VOP_UNLOCK(vp, 0); 2958 if (error) 2959 return (error); 2960 2961 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2962 NODEV, 0); 2963 return (0); 2964 } 2965 2966 static int 2967 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2968 { 2969 int error, new, n; 2970 2971 new = nsw_wcount_async_max; 2972 error = sysctl_handle_int(oidp, &new, 0, req); 2973 if (error != 0 || req->newptr == NULL) 2974 return (error); 2975 2976 if (new > nswbuf / 2 || new < 1) 2977 return (EINVAL); 2978 2979 mtx_lock(&swbuf_mtx); 2980 while (nsw_wcount_async_max != new) { 2981 /* 2982 * Adjust difference. If the current async count is too low, 2983 * we will need to sqeeze our update slowly in. Sleep with a 2984 * higher priority than getpbuf() to finish faster. 2985 */ 2986 n = new - nsw_wcount_async_max; 2987 if (nsw_wcount_async + n >= 0) { 2988 nsw_wcount_async += n; 2989 nsw_wcount_async_max += n; 2990 wakeup(&nsw_wcount_async); 2991 } else { 2992 nsw_wcount_async_max -= nsw_wcount_async; 2993 nsw_wcount_async = 0; 2994 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 2995 "swpsysctl", 0); 2996 } 2997 } 2998 mtx_unlock(&swbuf_mtx); 2999 3000 return (0); 3001 } 3002 3003 static void 3004 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3005 vm_offset_t end) 3006 { 3007 3008 VM_OBJECT_WLOCK(object); 3009 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3010 ("Splittable object with writecount")); 3011 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3012 VM_OBJECT_WUNLOCK(object); 3013 } 3014 3015 static void 3016 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3017 vm_offset_t end) 3018 { 3019 3020 VM_OBJECT_WLOCK(object); 3021 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3022 ("Splittable object with writecount")); 3023 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3024 VM_OBJECT_WUNLOCK(object); 3025 } 3026