diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c index c01b9e45a32b..676e585a6b53 100644 --- a/sys/vm/swap_pager.c +++ b/sys/vm/swap_pager.c @@ -1,3461 +1,3461 @@ /*- * SPDX-License-Identifier: BSD-4-Clause * * Copyright (c) 1998 Matthew Dillon, * Copyright (c) 1994 John S. Dyson * Copyright (c) 1990 University of Utah. * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * the Systems Programming Group of the University of Utah Computer * Science Department. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * New Swap System * Matthew Dillon * * Radix Bitmap 'blists'. * * - The new swapper uses the new radix bitmap code. This should scale * to arbitrarily small or arbitrarily large swap spaces and an almost * arbitrary degree of fragmentation. * * Features: * * - on the fly reallocation of swap during putpages. The new system * does not try to keep previously allocated swap blocks for dirty * pages. * * - on the fly deallocation of swap * * - No more garbage collection required. Unnecessarily allocated swap * blocks only exist for dirty vm_page_t's now and these are already * cycled (in a high-load system) by the pager. We also do on-the-fly * removal of invalidated swap blocks when a page is destroyed * or renamed. * * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ */ #include "opt_vm.h" #define EXTERR_CATEGORY EXTERR_CAT_SWAP #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. * The 64-page limit is due to the radix code (kern/subr_blist.c). */ #ifndef MAX_PAGEOUT_CLUSTER #define MAX_PAGEOUT_CLUSTER 32 #endif #if !defined(SWB_NPAGES) #define SWB_NPAGES MAX_PAGEOUT_CLUSTER #endif #define SWAP_META_PAGES PCTRIE_COUNT /* * A swblk structure maps each page index within a * SWAP_META_PAGES-aligned and sized range to the address of an * on-disk swap block (or SWAPBLK_NONE). The collection of these * mappings for an entire vm object is implemented as a pc-trie. */ struct swblk { vm_pindex_t p; daddr_t d[SWAP_META_PAGES]; }; /* * A page_range structure records the start address and length of a sequence of * mapped page addresses. */ struct page_range { daddr_t start; daddr_t num; }; static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); static struct mtx sw_dev_mtx; static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); static struct swdevt *swdevhd; /* Allocate from here next */ static int nswapdev; /* Number of swap devices */ int swap_pager_avail; static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ static __exclusive_cache_line u_long swap_reserved; static u_long swap_total; static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, "VM swap stats"); SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, &swap_reserved, 0, sysctl_page_shift, "QU", "Amount of swap storage needed to back all allocated anonymous memory."); SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, &swap_total, 0, sysctl_page_shift, "QU", "Total amount of available swap storage."); int vm_overcommit __read_mostly = 0; SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &vm_overcommit, 0, "Configure virtual memory overcommit behavior. See tuning(7) " "for details."); static unsigned long swzone; SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, "Actual size of swap metadata zone"); static unsigned long swap_maxpages; SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, "Maximum amount of swap supported"); static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, CTLFLAG_RD, &swap_free_deferred, "Number of pages that deferred freeing swap space"); static COUNTER_U64_DEFINE_EARLY(swap_free_completed); SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, CTLFLAG_RD, &swap_free_completed, "Number of deferred frees completed"); static int sysctl_page_shift(SYSCTL_HANDLER_ARGS) { uint64_t newval; u_long value = *(u_long *)arg1; newval = ((uint64_t)value) << PAGE_SHIFT; return (sysctl_handle_64(oidp, &newval, 0, req)); } static bool swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) { struct uidinfo *uip; u_long prev; uip = cred->cr_ruidinfo; prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); KASSERT(prev >= pincr, ("negative vmsize for uid %d\n", uip->ui_uid)); return (false); } return (true); } static void swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) { struct uidinfo *uip; #ifdef INVARIANTS u_long prev; #endif uip = cred->cr_ruidinfo; #ifdef INVARIANTS prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); KASSERT(prev >= pdecr, ("negative vmsize for uid %d\n", uip->ui_uid)); #else atomic_subtract_long(&uip->ui_vmsize, pdecr); #endif } static void swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) { struct uidinfo *uip; uip = cred->cr_ruidinfo; atomic_add_long(&uip->ui_vmsize, pincr); } bool swap_reserve(vm_ooffset_t incr) { return (swap_reserve_by_cred(incr, curthread->td_ucred)); } bool swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) { u_long r, s, prev, pincr; #ifdef RACCT int error; #endif int oc; static int curfail; static struct timeval lastfail; KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, (uintmax_t)incr)); #ifdef RACCT if (RACCT_ENABLED()) { PROC_LOCK(curproc); error = racct_add(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); if (error != 0) return (false); } #endif pincr = atop(incr); prev = atomic_fetchadd_long(&swap_reserved, pincr); r = prev + pincr; s = swap_total; oc = atomic_load_int(&vm_overcommit); if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_wire_count(); } if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { prev = atomic_fetchadd_long(&swap_reserved, -pincr); KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); goto out_error; } if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { prev = atomic_fetchadd_long(&swap_reserved, -pincr); KASSERT(prev >= pincr, ("swap_reserved < incr on overcommit fail")); goto out_error; } return (true); out_error: if (ppsratecheck(&lastfail, &curfail, 1)) { printf("uid %d, pid %d: swap reservation " "for %jd bytes failed\n", cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); } #ifdef RACCT if (RACCT_ENABLED()) { PROC_LOCK(curproc); racct_sub(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); } #endif return (false); } void swap_reserve_force(vm_ooffset_t incr) { u_long pincr; KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, (uintmax_t)incr)); #ifdef RACCT if (RACCT_ENABLED()) { PROC_LOCK(curproc); racct_add_force(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); } #endif pincr = atop(incr); atomic_add_long(&swap_reserved, pincr); swap_reserve_force_rlimit(pincr, curthread->td_ucred); } void swap_release(vm_ooffset_t decr) { struct ucred *cred; PROC_LOCK(curproc); cred = curproc->p_ucred; swap_release_by_cred(decr, cred); PROC_UNLOCK(curproc); } void swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) { u_long pdecr; #ifdef INVARIANTS u_long prev; #endif KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, (uintmax_t)decr)); pdecr = atop(decr); #ifdef INVARIANTS prev = atomic_fetchadd_long(&swap_reserved, -pdecr); KASSERT(prev >= pdecr, ("swap_reserved < decr")); #else atomic_subtract_long(&swap_reserved, pdecr); #endif swap_release_by_cred_rlimit(pdecr, cred); #ifdef RACCT if (racct_enable) racct_sub_cred(cred, RACCT_SWAP, decr); #endif } static bool swap_pager_full = true; /* swap space exhaustion (task killing) */ -static bool swap_pager_almost_full = true; /* swap space exhaustion (w/hysteresis) */ +bool swap_pager_almost_full = true; /* swap space exhaustion (w/hysteresis) */ static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ static int nsw_wcount_async; /* limit async write buffers */ static int nsw_wcount_async_max;/* assigned maximum */ int nsw_cluster_max; /* maximum VOP I/O allowed */ static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", "Maximum running async swap ops"); static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", "Swap Fragmentation Info"); static struct sx sw_alloc_sx; /* * "named" and "unnamed" anon region objects. Try to reduce the overhead * of searching a named list by hashing it just a little. */ #define NOBJLISTS 8 #define NOBJLIST(handle) \ (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) static struct pagerlst swap_pager_object_list[NOBJLISTS]; static uma_zone_t swwbuf_zone; static uma_zone_t swrbuf_zone; static uma_zone_t swblk_zone; static uma_zone_t swpctrie_zone; /* * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure * calls hooked from other parts of the VM system and do not appear here. * (see vm/swap_pager.h). */ static vm_object_t swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset, struct ucred *); static void swap_pager_dealloc(vm_object_t object); static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, int *, pgo_getpages_iodone_t, void *); static void swap_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); static boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); static void swap_pager_init(void); static void swap_pager_unswapped(vm_page_t); static void swap_pager_swapoff(struct swdevt *sp); static void swap_pager_update_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end); static void swap_pager_release_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end); static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size); const struct pagerops swappagerops = { .pgo_kvme_type = KVME_TYPE_SWAP, .pgo_init = swap_pager_init, /* early system initialization of pager */ .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ .pgo_getpages = swap_pager_getpages, /* pagein */ .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ .pgo_putpages = swap_pager_putpages, /* pageout */ .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ .pgo_update_writecount = swap_pager_update_writecount, .pgo_release_writecount = swap_pager_release_writecount, .pgo_freespace = swap_pager_freespace_pgo, }; /* * swap_*() routines are externally accessible. swp_*() routines are * internal. */ static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, "Maximum size of a swap block in pages"); static void swp_sizecheck(void); static void swp_pager_async_iodone(struct buf *bp); static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); static int swapongeom(struct vnode *); static int swaponvp(struct thread *, struct vnode *, u_long); static int swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags); /* * Swap bitmap functions */ static void swp_pager_freeswapspace(const struct page_range *range); static daddr_t swp_pager_getswapspace(int *npages); /* * Metadata functions */ static daddr_t swp_pager_meta_build(struct pctrie_iter *, vm_object_t object, vm_pindex_t, daddr_t, bool); static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t, vm_size_t *); static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, vm_pindex_t pindex, vm_pindex_t count); static void swp_pager_meta_free_all(vm_object_t); static daddr_t swp_pager_meta_lookup(struct pctrie_iter *, vm_pindex_t); static void swp_pager_init_freerange(struct page_range *range) { range->start = SWAPBLK_NONE; range->num = 0; } static void swp_pager_update_freerange(struct page_range *range, daddr_t addr) { if (range->start + range->num == addr) { range->num++; } else { swp_pager_freeswapspace(range); range->start = addr; range->num = 1; } } static void * swblk_trie_alloc(struct pctrie *ptree) { return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? M_USE_RESERVE : 0))); } static void swblk_trie_free(struct pctrie *ptree, void *node) { uma_zfree(swpctrie_zone, node); } static int swblk_start(struct swblk *sb, vm_pindex_t pindex) { return (sb == NULL || sb->p >= pindex ? 0 : pindex % SWAP_META_PAGES); } PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); static struct swblk * swblk_lookup(vm_object_t object, vm_pindex_t pindex) { return (SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rounddown(pindex, SWAP_META_PAGES))); } static void swblk_lookup_remove(vm_object_t object, struct swblk *sb) { SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); } static bool swblk_is_empty(vm_object_t object) { return (pctrie_is_empty(&object->un_pager.swp.swp_blks)); } static struct swblk * swblk_iter_lookup_ge(struct pctrie_iter *blks, vm_pindex_t pindex) { return (SWAP_PCTRIE_ITER_LOOKUP_GE(blks, rounddown(pindex, SWAP_META_PAGES))); } static void swblk_iter_init_only(struct pctrie_iter *blks, vm_object_t object) { VM_OBJECT_ASSERT_LOCKED(object); MPASS((object->flags & OBJ_SWAP) != 0); pctrie_iter_init(blks, &object->un_pager.swp.swp_blks); } static struct swblk * swblk_iter_init(struct pctrie_iter *blks, vm_object_t object, vm_pindex_t pindex) { swblk_iter_init_only(blks, object); return (swblk_iter_lookup_ge(blks, pindex)); } static struct swblk * swblk_iter_reinit(struct pctrie_iter *blks, vm_object_t object, vm_pindex_t pindex) { swblk_iter_init_only(blks, object); return (SWAP_PCTRIE_ITER_LOOKUP(blks, rounddown(pindex, SWAP_META_PAGES))); } static struct swblk * swblk_iter_limit_init(struct pctrie_iter *blks, vm_object_t object, vm_pindex_t pindex, vm_pindex_t limit) { VM_OBJECT_ASSERT_LOCKED(object); MPASS((object->flags & OBJ_SWAP) != 0); pctrie_iter_limit_init(blks, &object->un_pager.swp.swp_blks, limit); return (swblk_iter_lookup_ge(blks, pindex)); } static struct swblk * swblk_iter_next(struct pctrie_iter *blks) { return (SWAP_PCTRIE_ITER_JUMP_GE(blks, SWAP_META_PAGES)); } static struct swblk * swblk_iter_lookup(struct pctrie_iter *blks, vm_pindex_t pindex) { return (SWAP_PCTRIE_ITER_LOOKUP(blks, rounddown(pindex, SWAP_META_PAGES))); } static int swblk_iter_insert(struct pctrie_iter *blks, struct swblk *sb) { return (SWAP_PCTRIE_ITER_INSERT(blks, sb)); } static void swblk_iter_remove(struct pctrie_iter *blks) { SWAP_PCTRIE_ITER_REMOVE(blks); } /* * SWP_SIZECHECK() - update swap_pager_full indication * * update the swap_pager_almost_full indication and warn when we are * about to run out of swap space, using lowat/hiwat hysteresis. * * Clear swap_pager_full ( task killing ) indication when lowat is met. * * No restrictions on call * This routine may not block. */ static void swp_sizecheck(void) { if (swap_pager_avail < nswap_lowat) { if (!swap_pager_almost_full) { printf("swap_pager: out of swap space\n"); swap_pager_almost_full = true; } } else { swap_pager_full = false; if (swap_pager_avail > nswap_hiwat) swap_pager_almost_full = false; } } /* * SWAP_PAGER_INIT() - initialize the swap pager! * * Expected to be started from system init. NOTE: This code is run * before much else so be careful what you depend on. Most of the VM * system has yet to be initialized at this point. */ static void swap_pager_init(void) { /* * Initialize object lists */ int i; for (i = 0; i < NOBJLISTS; ++i) TAILQ_INIT(&swap_pager_object_list[i]); mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); sx_init(&sw_alloc_sx, "swspsx"); sx_init(&swdev_syscall_lock, "swsysc"); /* * The nsw_cluster_max is constrained by the bp->b_pages[] * array, which has maxphys / PAGE_SIZE entries, and our locally * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are * constrained by the swap device interleave stripe size. * * Initialized early so that GEOM_ELI can see it. */ nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); } /* * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process * * Expected to be started from pageout process once, prior to entering * its main loop. */ void swap_pager_swap_init(void) { unsigned long n, n2; /* * Number of in-transit swap bp operations. Don't * exhaust the pbufs completely. Make sure we * initialize workable values (0 will work for hysteresis * but it isn't very efficient). * * Currently we hardwire nsw_wcount_async to 4. This limit is * designed to prevent other I/O from having high latencies due to * our pageout I/O. The value 4 works well for one or two active swap * devices but is probably a little low if you have more. Even so, * a higher value would probably generate only a limited improvement * with three or four active swap devices since the system does not * typically have to pageout at extreme bandwidths. We will want * at least 2 per swap devices, and 4 is a pretty good value if you * have one NFS swap device due to the command/ack latency over NFS. * So it all works out pretty well. * * nsw_cluster_max is initialized in swap_pager_init(). */ nsw_wcount_async = 4; nsw_wcount_async_max = nsw_wcount_async; mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); /* * Initialize our zone, taking the user's requested size or * estimating the number we need based on the number of pages * in the system. */ n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : vm_cnt.v_page_count / 2; swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, NULL, NULL, _Alignof(struct swblk) - 1, 0); n2 = n; do { if (uma_zone_reserve_kva(swblk_zone, n)) break; /* * if the allocation failed, try a zone two thirds the * size of the previous attempt. */ n -= ((n + 2) / 3); } while (n > 0); /* * Often uma_zone_reserve_kva() cannot reserve exactly the * requested size. Account for the difference when * calculating swap_maxpages. */ n = uma_zone_get_max(swblk_zone); if (n < n2) printf("Swap blk zone entries changed from %lu to %lu.\n", n2, n); /* absolute maximum we can handle assuming 100% efficiency */ swap_maxpages = n * SWAP_META_PAGES; swzone = n * sizeof(struct swblk); if (!uma_zone_reserve_kva(swpctrie_zone, n)) printf("Cannot reserve swap pctrie zone, " "reduce kern.maxswzone.\n"); } bool swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, vm_ooffset_t size, vm_ooffset_t offset) { if (cred != NULL) { if (!swap_reserve_by_cred(size, cred)) return (false); crhold(cred); } object->un_pager.swp.writemappings = 0; object->handle = handle; if (cred != NULL) { object->cred = cred; object->charge = size; } return (true); } static vm_object_t swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred, vm_ooffset_t size, vm_ooffset_t offset) { vm_object_t object; /* * The un_pager.swp.swp_blks trie is initialized by * vm_object_allocate() to ensure the correct order of * visibility to other threads. */ object = vm_object_allocate(otype, OFF_TO_IDX(offset + PAGE_MASK + size)); if (!swap_pager_init_object(object, handle, cred, size, offset)) { vm_object_deallocate(object); return (NULL); } return (object); } /* * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate * its metadata structures. * * This routine is called from the mmap and fork code to create a new * OBJT_SWAP object. * * This routine must ensure that no live duplicate is created for * the named object request, which is protected against by * holding the sw_alloc_sx lock in case handle != NULL. */ static vm_object_t swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset, struct ucred *cred) { vm_object_t object; if (handle != NULL) { /* * Reference existing named region or allocate new one. There * should not be a race here against swp_pager_meta_build() * as called from vm_page_remove() in regards to the lookup * of the handle. */ sx_xlock(&sw_alloc_sx); object = vm_pager_object_lookup(NOBJLIST(handle), handle); if (object == NULL) { object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, size, offset); if (object != NULL) { TAILQ_INSERT_TAIL(NOBJLIST(object->handle), object, pager_object_list); } } sx_xunlock(&sw_alloc_sx); } else { object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, size, offset); } return (object); } /* * SWAP_PAGER_DEALLOC() - remove swap metadata from object * * The swap backing for the object is destroyed. The code is * designed such that we can reinstantiate it later, but this * routine is typically called only when the entire object is * about to be destroyed. * * The object must be locked. */ static void swap_pager_dealloc(vm_object_t object) { VM_OBJECT_ASSERT_WLOCKED(object); KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); /* * Remove from list right away so lookups will fail if we block for * pageout completion. */ if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { VM_OBJECT_WUNLOCK(object); sx_xlock(&sw_alloc_sx); TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); sx_xunlock(&sw_alloc_sx); VM_OBJECT_WLOCK(object); } vm_object_pip_wait(object, "swpdea"); /* * Free all remaining metadata. We only bother to free it from * the swap meta data. We do not attempt to free swapblk's still * associated with vm_page_t's for this object. We do not care * if paging is still in progress on some objects. */ swp_pager_meta_free_all(object); object->handle = NULL; object->type = OBJT_DEAD; /* * Release the allocation charge. */ if (object->cred != NULL) { swap_release_by_cred(object->charge, object->cred); object->charge = 0; crfree(object->cred); object->cred = NULL; } /* * Hide the object from swap_pager_swapoff(). */ vm_object_clear_flag(object, OBJ_SWAP); } /************************************************************************ * SWAP PAGER BITMAP ROUTINES * ************************************************************************/ /* * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space * * Allocate swap for up to the requested number of pages. The * starting swap block number (a page index) is returned or * SWAPBLK_NONE if the allocation failed. * * Also has the side effect of advising that somebody made a mistake * when they configured swap and didn't configure enough. * * This routine may not sleep. * * We allocate in round-robin fashion from the configured devices. */ static daddr_t swp_pager_getswapspace(int *io_npages) { daddr_t blk; struct swdevt *sp; int mpages, npages; KASSERT(*io_npages >= 1, ("%s: npages not positive", __func__)); blk = SWAPBLK_NONE; mpages = *io_npages; npages = imin(BLIST_MAX_ALLOC, mpages); mtx_lock(&sw_dev_mtx); sp = swdevhd; while (!TAILQ_EMPTY(&swtailq)) { if (sp == NULL) sp = TAILQ_FIRST(&swtailq); if ((sp->sw_flags & SW_CLOSING) == 0) blk = blist_alloc(sp->sw_blist, &npages, mpages); if (blk != SWAPBLK_NONE) break; sp = TAILQ_NEXT(sp, sw_list); if (swdevhd == sp) { if (npages == 1) break; mpages = npages - 1; npages >>= 1; } } if (blk != SWAPBLK_NONE) { *io_npages = npages; blk += sp->sw_first; sp->sw_used += npages; swap_pager_avail -= npages; swp_sizecheck(); swdevhd = TAILQ_NEXT(sp, sw_list); } else { if (!swap_pager_full) { printf("swp_pager_getswapspace(%d): failed\n", *io_npages); swap_pager_full = swap_pager_almost_full = true; } swdevhd = NULL; } mtx_unlock(&sw_dev_mtx); return (blk); } static bool swp_pager_isondev(daddr_t blk, struct swdevt *sp) { return (blk >= sp->sw_first && blk < sp->sw_end); } static void swp_pager_strategy(struct buf *bp) { struct swdevt *sp; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (swp_pager_isondev(bp->b_blkno, sp)) { mtx_unlock(&sw_dev_mtx); if ((sp->sw_flags & SW_UNMAPPED) != 0 && unmapped_buf_allowed) { bp->b_data = unmapped_buf; bp->b_offset = 0; } else { pmap_qenter((vm_offset_t)bp->b_data, &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); } sp->sw_strategy(bp, sp); return; } } panic("Swapdev not found"); } /* * SWP_PAGER_FREESWAPSPACE() - free raw swap space * * This routine returns the specified swap blocks back to the bitmap. * * This routine may not sleep. */ static void swp_pager_freeswapspace(const struct page_range *range) { daddr_t blk, npages; struct swdevt *sp; blk = range->start; npages = range->num; if (npages == 0) return; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (swp_pager_isondev(blk, sp)) { sp->sw_used -= npages; /* * If we are attempting to stop swapping on * this device, we don't want to mark any * blocks free lest they be reused. */ if ((sp->sw_flags & SW_CLOSING) == 0) { blist_free(sp->sw_blist, blk - sp->sw_first, npages); swap_pager_avail += npages; swp_sizecheck(); } mtx_unlock(&sw_dev_mtx); return; } } panic("Swapdev not found"); } /* * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats */ static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) { struct sbuf sbuf; struct swdevt *sp; const char *devname; int error; error = sysctl_wire_old_buffer(req, 0); if (error != 0) return (error); sbuf_new_for_sysctl(&sbuf, NULL, 128, req); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (vn_isdisk(sp->sw_vp)) devname = devtoname(sp->sw_vp->v_rdev); else devname = "[file]"; sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); blist_stats(sp->sw_blist, &sbuf); } mtx_unlock(&sw_dev_mtx); error = sbuf_finish(&sbuf); sbuf_delete(&sbuf); return (error); } /* * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page * range within an object. * * This routine removes swapblk assignments from swap metadata. * * The external callers of this routine typically have already destroyed * or renamed vm_page_t's associated with this range in the object so * we should be ok. * * The object must be locked. */ void swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size, vm_size_t *freed) { MPASS((object->flags & OBJ_SWAP) != 0); swp_pager_meta_free(object, start, size, freed); } static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size) { MPASS((object->flags & OBJ_SWAP) != 0); swp_pager_meta_free(object, start, size, NULL); } /* * SWAP_PAGER_RESERVE() - reserve swap blocks in object * * Assigns swap blocks to the specified range within the object. The * swap blocks are not zeroed. Any previous swap assignment is destroyed. * * Returns 0 on success, -1 on failure. */ int swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size) { struct pctrie_iter blks; struct page_range range; daddr_t addr, blk; vm_pindex_t i, j; int n; swp_pager_init_freerange(&range); VM_OBJECT_WLOCK(object); swblk_iter_init_only(&blks, object); for (i = 0; i < size; i += n) { n = MIN(size - i, INT_MAX); blk = swp_pager_getswapspace(&n); if (blk == SWAPBLK_NONE) { swp_pager_meta_free(object, start, i, NULL); VM_OBJECT_WUNLOCK(object); return (-1); } for (j = 0; j < n; ++j) { addr = swp_pager_meta_build(&blks, object, start + i + j, blk + j, false); if (addr != SWAPBLK_NONE) swp_pager_update_freerange(&range, addr); } } swp_pager_freeswapspace(&range); VM_OBJECT_WUNLOCK(object); return (0); } /* * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager * and destroy the source. * * Copy any valid swapblks from the source to the destination. In * cases where both the source and destination have a valid swapblk, * we keep the destination's. * * This routine is allowed to sleep. It may sleep allocating metadata * indirectly through swp_pager_meta_build(). * * The source object contains no vm_page_t's (which is just as well) * * The source and destination objects must be locked. * Both object locks may temporarily be released. */ void swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, vm_pindex_t offset, int destroysource) { VM_OBJECT_ASSERT_WLOCKED(srcobject); VM_OBJECT_ASSERT_WLOCKED(dstobject); /* * If destroysource is set, we remove the source object from the * swap_pager internal queue now. */ if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && srcobject->handle != NULL) { VM_OBJECT_WUNLOCK(srcobject); VM_OBJECT_WUNLOCK(dstobject); sx_xlock(&sw_alloc_sx); TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, pager_object_list); sx_xunlock(&sw_alloc_sx); VM_OBJECT_WLOCK(dstobject); VM_OBJECT_WLOCK(srcobject); } /* * Transfer source to destination. */ swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); /* * Free left over swap blocks in source. */ if (destroysource) swp_pager_meta_free_all(srcobject); } /* * SWP_PAGER_HASPAGE_ITER() - determine if we have good backing store for * the requested page, accessed with the given * iterator. * * We determine whether good backing store exists for the requested * page and return TRUE if it does, FALSE if it doesn't. * * If TRUE, we also try to determine how much valid, contiguous backing * store exists before and after the requested page. */ static boolean_t swp_pager_haspage_iter(vm_pindex_t pindex, int *before, int *after, struct pctrie_iter *blks) { daddr_t blk, blk0; int i; /* * do we have good backing store at the requested index ? */ blk0 = swp_pager_meta_lookup(blks, pindex); if (blk0 == SWAPBLK_NONE) { if (before) *before = 0; if (after) *after = 0; return (FALSE); } /* * find backwards-looking contiguous good backing store */ if (before != NULL) { for (i = 1; i < SWB_NPAGES; i++) { if (i > pindex) break; blk = swp_pager_meta_lookup(blks, pindex - i); if (blk != blk0 - i) break; } *before = i - 1; } /* * find forward-looking contiguous good backing store */ if (after != NULL) { for (i = 1; i < SWB_NPAGES; i++) { blk = swp_pager_meta_lookup(blks, pindex + i); if (blk != blk0 + i) break; } *after = i - 1; } return (TRUE); } /* * SWAP_PAGER_HASPAGE() - determine if we have good backing store for * the requested page, in the given object. * * We determine whether good backing store exists for the requested * page and return TRUE if it does, FALSE if it doesn't. * * If TRUE, we also try to determine how much valid, contiguous backing * store exists before and after the requested page. */ static boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) { struct pctrie_iter blks; swblk_iter_init_only(&blks, object); return (swp_pager_haspage_iter(pindex, before, after, &blks)); } static void swap_pager_unswapped_acct(vm_page_t m) { KASSERT((m->object->flags & OBJ_SWAP) != 0, ("Free object not swappable")); if ((m->a.flags & PGA_SWAP_FREE) != 0) counter_u64_add(swap_free_completed, 1); vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); /* * The meta data only exists if the object is OBJT_SWAP * and even then might not be allocated yet. */ } /* * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page * * This removes any associated swap backing store, whether valid or * not, from the page. * * This routine is typically called when a page is made dirty, at * which point any associated swap can be freed. MADV_FREE also * calls us in a special-case situation * * NOTE!!! If the page is clean and the swap was valid, the caller * should make the page dirty before calling this routine. This routine * does NOT change the m->dirty status of the page. Also: MADV_FREE * depends on it. * * This routine may not sleep. * * The object containing the page may be locked. */ static void swap_pager_unswapped(vm_page_t m) { struct page_range range; struct swblk *sb; vm_object_t obj; /* * Handle enqueing deferred frees first. If we do not have the * object lock we wait for the page daemon to clear the space. */ obj = m->object; if (!VM_OBJECT_WOWNED(obj)) { VM_PAGE_OBJECT_BUSY_ASSERT(m); /* * The caller is responsible for synchronization but we * will harmlessly handle races. This is typically provided * by only calling unswapped() when a page transitions from * clean to dirty. */ if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == PGA_SWAP_SPACE) { vm_page_aflag_set(m, PGA_SWAP_FREE); counter_u64_add(swap_free_deferred, 1); } return; } swap_pager_unswapped_acct(m); sb = swblk_lookup(m->object, m->pindex); if (sb == NULL) return; range.start = sb->d[m->pindex % SWAP_META_PAGES]; if (range.start == SWAPBLK_NONE) return; range.num = 1; swp_pager_freeswapspace(&range); sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; swp_pager_free_empty_swblk(m->object, sb); } /* * swap_pager_getpages_locked() - bring pages in from swap * * Attempt to page in the pages in array "ma" of length "count". The * caller may optionally specify that additional pages preceding and * succeeding the specified range be paged in. The number of such pages * is returned in the "a_rbehind" and "a_rahead" parameters, and they will * be in the inactive queue upon return. * * The pages in "ma" must be busied and will remain busied upon return. */ static int swap_pager_getpages_locked(struct pctrie_iter *blks, vm_object_t object, vm_page_t *ma, int count, int *a_rbehind, int *a_rahead, struct buf *bp) { vm_pindex_t pindex; int rahead, rbehind; VM_OBJECT_ASSERT_WLOCKED(object); KASSERT((object->flags & OBJ_SWAP) != 0, ("%s: object not swappable", __func__)); pindex = ma[0]->pindex; if (!swp_pager_haspage_iter(pindex, &rbehind, &rahead, blks)) { VM_OBJECT_WUNLOCK(object); uma_zfree(swrbuf_zone, bp); return (VM_PAGER_FAIL); } KASSERT(count - 1 <= rahead, ("page count %d extends beyond swap block", count)); /* * Do not transfer any pages other than those that are xbusied * when running during a split or collapse operation. This * prevents clustering from re-creating pages which are being * moved into another object. */ if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { rahead = count - 1; rbehind = 0; } /* Clip readbehind/ahead ranges to exclude already resident pages. */ rbehind = a_rbehind != NULL ? imin(*a_rbehind, rbehind) : 0; rahead = a_rahead != NULL ? imin(*a_rahead, rahead - count + 1) : 0; /* Allocate pages. */ vm_object_prepare_buf_pages(object, bp->b_pages, count, &rbehind, &rahead, ma); bp->b_npages = rbehind + count + rahead; for (int i = 0; i < bp->b_npages; i++) bp->b_pages[i]->oflags |= VPO_SWAPINPROG; bp->b_blkno = swp_pager_meta_lookup(blks, pindex - rbehind); KASSERT(bp->b_blkno != SWAPBLK_NONE, ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); vm_object_pip_add(object, bp->b_npages); VM_OBJECT_WUNLOCK(object); MPASS((bp->b_flags & B_MAXPHYS) != 0); /* Report back actual behind/ahead read. */ if (a_rbehind != NULL) *a_rbehind = rbehind; if (a_rahead != NULL) *a_rahead = rahead; bp->b_flags |= B_PAGING; bp->b_iocmd = BIO_READ; bp->b_iodone = swp_pager_async_iodone; bp->b_rcred = crhold(thread0.td_ucred); bp->b_wcred = crhold(thread0.td_ucred); bp->b_bufsize = bp->b_bcount = ptoa(bp->b_npages); bp->b_pgbefore = rbehind; bp->b_pgafter = rahead; VM_CNT_INC(v_swapin); VM_CNT_ADD(v_swappgsin, bp->b_npages); /* * perform the I/O. NOTE!!! bp cannot be considered valid after * this point because we automatically release it on completion. * Instead, we look at the one page we are interested in which we * still hold a lock on even through the I/O completion. * * The other pages in our ma[] array are also released on completion, * so we cannot assume they are valid anymore either. * * NOTE: b_blkno is destroyed by the call to swapdev_strategy */ BUF_KERNPROC(bp); swp_pager_strategy(bp); /* * Wait for the pages we want to complete. VPO_SWAPINPROG is always * cleared on completion. If an I/O error occurs, SWAPBLK_NONE * is set in the metadata for each page in the request. */ VM_OBJECT_WLOCK(object); /* This could be implemented more efficiently with aflags */ while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { ma[0]->oflags |= VPO_SWAPSLEEP; VM_CNT_INC(v_intrans); if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, "swread", hz * 20)) { printf( "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); } } VM_OBJECT_WUNLOCK(object); /* * If we had an unrecoverable read error pages will not be valid. */ for (int i = 0; i < count; i++) if (ma[i]->valid != VM_PAGE_BITS_ALL) return (VM_PAGER_ERROR); return (VM_PAGER_OK); /* * A final note: in a low swap situation, we cannot deallocate swap * and mark a page dirty here because the caller is likely to mark * the page clean when we return, causing the page to possibly revert * to all-zero's later. */ } static int swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, int *rahead) { struct buf *bp; struct pctrie_iter blks; bp = uma_zalloc(swrbuf_zone, M_WAITOK); VM_OBJECT_WLOCK(object); swblk_iter_init_only(&blks, object); return (swap_pager_getpages_locked(&blks, object, ma, count, rbehind, rahead, bp)); } /* * swap_pager_getpages_async(): * * Right now this is emulation of asynchronous operation on top of * swap_pager_getpages(). */ static int swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) { int r, error; r = swap_pager_getpages(object, ma, count, rbehind, rahead); switch (r) { case VM_PAGER_OK: error = 0; break; case VM_PAGER_ERROR: error = EIO; break; case VM_PAGER_FAIL: error = EINVAL; break; default: panic("unhandled swap_pager_getpages() error %d", r); } (iodone)(arg, ma, count, error); return (r); } /* * swap_pager_putpages: * * Assign swap (if necessary) and initiate I/O on the specified pages. * * In a low memory situation we may block in VOP_STRATEGY(), but the new * vm_page reservation system coupled with properly written VFS devices * should ensure that no low-memory deadlock occurs. This is an area * which needs work. * * The parent has N vm_object_pip_add() references prior to * calling us and will remove references for rtvals[] that are * not set to VM_PAGER_PEND. We need to remove the rest on I/O * completion. * * The parent has soft-busy'd the pages it passes us and will unbusy * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. * We need to unbusy the rest on I/O completion. */ static void swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, int flags, int *rtvals) { struct pctrie_iter blks; struct page_range range; struct buf *bp; daddr_t addr, blk; vm_page_t mreq; int i, j, n; bool async; KASSERT(count == 0 || ma[0]->object == object, ("%s: object mismatch %p/%p", __func__, object, ma[0]->object)); VM_OBJECT_WUNLOCK(object); async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; swp_pager_init_freerange(&range); /* * Assign swap blocks and issue I/O. We reallocate swap on the fly. * The page is left dirty until the pageout operation completes * successfully. */ for (i = 0; i < count; i += n) { /* Maximum I/O size is limited by maximum swap block size. */ n = min(count - i, nsw_cluster_max); if (async) { mtx_lock(&swbuf_mtx); while (nsw_wcount_async == 0) msleep(&nsw_wcount_async, &swbuf_mtx, PVM, "swbufa", 0); nsw_wcount_async--; mtx_unlock(&swbuf_mtx); } /* Get a block of swap of size up to size n. */ blk = swp_pager_getswapspace(&n); if (blk == SWAPBLK_NONE) { mtx_lock(&swbuf_mtx); if (++nsw_wcount_async == 1) wakeup(&nsw_wcount_async); mtx_unlock(&swbuf_mtx); for (j = 0; j < n; ++j) rtvals[i + j] = VM_PAGER_FAIL; continue; } VM_OBJECT_WLOCK(object); swblk_iter_init_only(&blks, object); for (j = 0; j < n; ++j) { mreq = ma[i + j]; vm_page_aflag_clear(mreq, PGA_SWAP_FREE); KASSERT(mreq->object == object, ("%s: object mismatch %p/%p", __func__, mreq->object, object)); addr = swp_pager_meta_build(&blks, object, mreq->pindex, blk + j, false); if (addr != SWAPBLK_NONE) swp_pager_update_freerange(&range, addr); MPASS(mreq->dirty == VM_PAGE_BITS_ALL); mreq->oflags |= VPO_SWAPINPROG; } VM_OBJECT_WUNLOCK(object); bp = uma_zalloc(swwbuf_zone, M_WAITOK); MPASS((bp->b_flags & B_MAXPHYS) != 0); if (async) bp->b_flags |= B_ASYNC; bp->b_flags |= B_PAGING; bp->b_iocmd = BIO_WRITE; bp->b_rcred = crhold(thread0.td_ucred); bp->b_wcred = crhold(thread0.td_ucred); bp->b_bcount = PAGE_SIZE * n; bp->b_bufsize = PAGE_SIZE * n; bp->b_blkno = blk; for (j = 0; j < n; j++) bp->b_pages[j] = ma[i + j]; bp->b_npages = n; /* * Must set dirty range for NFS to work. */ bp->b_dirtyoff = 0; bp->b_dirtyend = bp->b_bcount; VM_CNT_INC(v_swapout); VM_CNT_ADD(v_swappgsout, bp->b_npages); /* * We unconditionally set rtvals[] to VM_PAGER_PEND so that we * can call the async completion routine at the end of a * synchronous I/O operation. Otherwise, our caller would * perform duplicate unbusy and wakeup operations on the page * and object, respectively. */ for (j = 0; j < n; j++) rtvals[i + j] = VM_PAGER_PEND; /* * asynchronous * * NOTE: b_blkno is destroyed by the call to swapdev_strategy. */ if (async) { bp->b_iodone = swp_pager_async_iodone; BUF_KERNPROC(bp); swp_pager_strategy(bp); continue; } /* * synchronous * * NOTE: b_blkno is destroyed by the call to swapdev_strategy. */ bp->b_iodone = bdone; swp_pager_strategy(bp); /* * Wait for the sync I/O to complete. */ bwait(bp, PVM, "swwrt"); /* * Now that we are through with the bp, we can call the * normal async completion, which frees everything up. */ swp_pager_async_iodone(bp); } swp_pager_freeswapspace(&range); VM_OBJECT_WLOCK(object); } /* * swp_pager_async_iodone: * * Completion routine for asynchronous reads and writes from/to swap. * Also called manually by synchronous code to finish up a bp. * * This routine may not sleep. */ static void swp_pager_async_iodone(struct buf *bp) { int i; vm_object_t object = NULL; /* * Report error - unless we ran out of memory, in which case * we've already logged it in swapgeom_strategy(). */ if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { printf( "swap_pager: I/O error - %s failed; blkno %ld," "size %ld, error %d\n", ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), (long)bp->b_blkno, (long)bp->b_bcount, bp->b_error ); } /* * remove the mapping for kernel virtual */ if (buf_mapped(bp)) pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); else bp->b_data = bp->b_kvabase; if (bp->b_npages) { object = bp->b_pages[0]->object; VM_OBJECT_WLOCK(object); } /* * cleanup pages. If an error occurs writing to swap, we are in * very serious trouble. If it happens to be a disk error, though, * we may be able to recover by reassigning the swap later on. So * in this case we remove the m->swapblk assignment for the page * but do not free it in the rlist. The errornous block(s) are thus * never reallocated as swap. Redirty the page and continue. */ for (i = 0; i < bp->b_npages; ++i) { vm_page_t m = bp->b_pages[i]; m->oflags &= ~VPO_SWAPINPROG; if (m->oflags & VPO_SWAPSLEEP) { m->oflags &= ~VPO_SWAPSLEEP; wakeup(&object->handle); } /* We always have space after I/O, successful or not. */ vm_page_aflag_set(m, PGA_SWAP_SPACE); if (bp->b_ioflags & BIO_ERROR) { /* * If an error occurs I'd love to throw the swapblk * away without freeing it back to swapspace, so it * can never be used again. But I can't from an * interrupt. */ if (bp->b_iocmd == BIO_READ) { /* * NOTE: for reads, m->dirty will probably * be overridden by the original caller of * getpages so don't play cute tricks here. */ vm_page_invalid(m); if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter) vm_page_free_invalid(m); } else { /* * If a write error occurs, reactivate page * so it doesn't clog the inactive list, * then finish the I/O. */ MPASS(m->dirty == VM_PAGE_BITS_ALL); /* PQ_UNSWAPPABLE? */ vm_page_activate(m); vm_page_sunbusy(m); } } else if (bp->b_iocmd == BIO_READ) { /* * NOTE: for reads, m->dirty will probably be * overridden by the original caller of getpages so * we cannot set them in order to free the underlying * swap in a low-swap situation. I don't think we'd * want to do that anyway, but it was an optimization * that existed in the old swapper for a time before * it got ripped out due to precisely this problem. */ KASSERT(!pmap_page_is_mapped(m), ("swp_pager_async_iodone: page %p is mapped", m)); KASSERT(m->dirty == 0, ("swp_pager_async_iodone: page %p is dirty", m)); vm_page_valid(m); if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter) vm_page_readahead_finish(m); } else { /* * For write success, clear the dirty * status, then finish the I/O ( which decrements the * busy count and possibly wakes waiter's up ). * A page is only written to swap after a period of * inactivity. Therefore, we do not expect it to be * reused. */ KASSERT(!pmap_page_is_write_mapped(m), ("swp_pager_async_iodone: page %p is not write" " protected", m)); vm_page_undirty(m); vm_page_deactivate_noreuse(m); vm_page_sunbusy(m); } } /* * adjust pip. NOTE: the original parent may still have its own * pip refs on the object. */ if (object != NULL) { vm_object_pip_wakeupn(object, bp->b_npages); VM_OBJECT_WUNLOCK(object); } /* * swapdev_strategy() manually sets b_vp and b_bufobj before calling * bstrategy(). Set them back to NULL now we're done with it, or we'll * trigger a KASSERT in relpbuf(). */ if (bp->b_vp) { bp->b_vp = NULL; bp->b_bufobj = NULL; } /* * release the physical I/O buffer */ if (bp->b_flags & B_ASYNC) { mtx_lock(&swbuf_mtx); if (++nsw_wcount_async == 1) wakeup(&nsw_wcount_async); mtx_unlock(&swbuf_mtx); } uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); } int swap_pager_nswapdev(void) { return (nswapdev); } static void swp_pager_force_dirty(struct page_range *range, vm_page_t m, daddr_t *blk) { vm_page_dirty(m); swap_pager_unswapped_acct(m); swp_pager_update_freerange(range, *blk); *blk = SWAPBLK_NONE; vm_page_launder(m); } u_long swap_pager_swapped_pages(vm_object_t object) { struct pctrie_iter blks; struct swblk *sb; u_long res; int i; VM_OBJECT_ASSERT_LOCKED(object); if (swblk_is_empty(object)) return (0); res = 0; for (sb = swblk_iter_init(&blks, object, 0); sb != NULL; sb = swblk_iter_next(&blks)) { for (i = 0; i < SWAP_META_PAGES; i++) { if (sb->d[i] != SWAPBLK_NONE) res++; } } return (res); } /* * swap_pager_swapoff_object: * * Page in all of the pages that have been paged out for an object * to a swap device. */ static void swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object, struct buf **bp) { struct pctrie_iter blks, pages; struct page_range range; struct swblk *sb; vm_page_t m; int i, rahead, rv; bool sb_empty; VM_OBJECT_ASSERT_WLOCKED(object); KASSERT((object->flags & OBJ_SWAP) != 0, ("%s: Object not swappable", __func__)); KASSERT((object->flags & OBJ_DEAD) == 0, ("%s: Object already dead", __func__)); KASSERT((sp->sw_flags & SW_CLOSING) != 0, ("%s: Device not blocking further allocations", __func__)); vm_page_iter_init(&pages, object); swp_pager_init_freerange(&range); sb = swblk_iter_init(&blks, object, 0); while (sb != NULL) { sb_empty = true; for (i = 0; i < SWAP_META_PAGES; i++) { /* Skip an invalid block. */ if (sb->d[i] == SWAPBLK_NONE) continue; /* Skip a block not of this device. */ if (!swp_pager_isondev(sb->d[i], sp)) { sb_empty = false; continue; } /* * Look for a page corresponding to this block. If the * found page has pending operations, sleep and restart * the scan. */ m = vm_radix_iter_lookup(&pages, blks.index + i); if (m != NULL && (m->oflags & VPO_SWAPINPROG) != 0) { m->oflags |= VPO_SWAPSLEEP; VM_OBJECT_SLEEP(object, &object->handle, PSWP, "swpoff", 0); break; } /* * If the found page is valid, mark it dirty and free * the swap block. */ if (m != NULL && vm_page_all_valid(m)) { swp_pager_force_dirty(&range, m, &sb->d[i]); continue; } /* Is there a page we can acquire or allocate? */ if (m != NULL) { if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) break; } else { m = vm_page_alloc_iter(object, blks.index + i, VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL, &pages); if (m == NULL) break; } /* Get the page from swap, and restart the scan. */ vm_object_pip_add(object, 1); rahead = SWAP_META_PAGES; rv = swap_pager_getpages_locked(&blks, object, &m, 1, NULL, &rahead, *bp); if (rv != VM_PAGER_OK) panic("%s: read from swap failed: %d", __func__, rv); *bp = uma_zalloc(swrbuf_zone, M_WAITOK); VM_OBJECT_WLOCK(object); vm_object_pip_wakeupn(object, 1); KASSERT(vm_page_all_valid(m), ("%s: Page %p not all valid", __func__, m)); vm_page_deactivate_noreuse(m); vm_page_xunbusy(m); break; } if (i < SWAP_META_PAGES) { /* * The object lock has been released and regained. * Perhaps the object is now dead. */ if ((object->flags & OBJ_DEAD) != 0) { /* * Make sure that pending writes finish before * returning. */ vm_object_pip_wait(object, "swpoff"); swp_pager_meta_free_all(object); break; } /* * The swapblk could have been freed, so reset the pages * iterator and search again for the first swblk at or * after blks.index. */ pctrie_iter_reset(&pages); sb = swblk_iter_init(&blks, object, blks.index); continue; } if (sb_empty) { swblk_iter_remove(&blks); uma_zfree(swblk_zone, sb); } /* * It is safe to advance to the next block. No allocations * before blk.index have happened, even with the lock released, * because allocations on this device are blocked. */ sb = swblk_iter_next(&blks); } swp_pager_freeswapspace(&range); } /* * swap_pager_swapoff: * * Page in all of the pages that have been paged out to the * given device. The corresponding blocks in the bitmap must be * marked as allocated and the device must be flagged SW_CLOSING. * There may be no processes swapped out to the device. * * This routine may block. */ static void swap_pager_swapoff(struct swdevt *sp) { vm_object_t object; struct buf *bp; int retries; sx_assert(&swdev_syscall_lock, SA_XLOCKED); retries = 0; full_rescan: bp = uma_zalloc(swrbuf_zone, M_WAITOK); mtx_lock(&vm_object_list_mtx); TAILQ_FOREACH(object, &vm_object_list, object_list) { if ((object->flags & OBJ_SWAP) == 0) continue; mtx_unlock(&vm_object_list_mtx); /* Depends on type-stability. */ VM_OBJECT_WLOCK(object); /* * Dead objects are eventually terminated on their own. */ if ((object->flags & OBJ_DEAD) != 0) goto next_obj; /* * Sync with fences placed after pctrie * initialization. We must not access pctrie below * unless we checked that our object is swap and not * dead. */ atomic_thread_fence_acq(); if ((object->flags & OBJ_SWAP) == 0) goto next_obj; swap_pager_swapoff_object(sp, object, &bp); next_obj: VM_OBJECT_WUNLOCK(object); mtx_lock(&vm_object_list_mtx); } mtx_unlock(&vm_object_list_mtx); uma_zfree(swrbuf_zone, bp); if (sp->sw_used) { /* * Objects may be locked or paging to the device being * removed, so we will miss their pages and need to * make another pass. We have marked this device as * SW_CLOSING, so the activity should finish soon. */ retries++; if (retries > 100) { panic("swapoff: failed to locate %d swap blocks", sp->sw_used); } pause("swpoff", hz / 20); goto full_rescan; } EVENTHANDLER_INVOKE(swapoff, sp); } /************************************************************************ * SWAP META DATA * ************************************************************************ * * These routines manipulate the swap metadata stored in the * OBJT_SWAP object. * * Swap metadata is implemented with a global hash and not directly * linked into the object. Instead the object simply contains * appropriate tracking counters. */ /* * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? */ static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit) { int i; MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); for (i = start; i < limit; i++) { if (sb->d[i] != SWAPBLK_NONE) return (false); } return (true); } /* * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free * * Nothing is done if the block is still in use. */ static void swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) { if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { swblk_lookup_remove(object, sb); uma_zfree(swblk_zone, sb); } } /* * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object * * Try to add the specified swapblk to the object's swap metadata. If * nowait_noreplace is set, add the specified swapblk only if there is no * previously assigned swapblk at pindex. If the swapblk is invalid, and * replaces a valid swapblk, empty swap metadata is freed. If memory * allocation fails, and nowait_noreplace is set, return the specified * swapblk immediately to indicate failure; otherwise, wait and retry until * memory allocation succeeds. Return the previously assigned swapblk, if * any. */ static daddr_t swp_pager_meta_build(struct pctrie_iter *blks, vm_object_t object, vm_pindex_t pindex, daddr_t swapblk, bool nowait_noreplace) { static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; struct swblk *sb, *sb1; vm_pindex_t modpi; daddr_t prev_swapblk; int error, i; VM_OBJECT_ASSERT_WLOCKED(object); sb = swblk_iter_lookup(blks, pindex); if (sb == NULL) { if (swapblk == SWAPBLK_NONE) return (SWAPBLK_NONE); for (;;) { sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == pageproc ? M_USE_RESERVE : 0)); if (sb != NULL) { sb->p = rounddown(pindex, SWAP_META_PAGES); for (i = 0; i < SWAP_META_PAGES; i++) sb->d[i] = SWAPBLK_NONE; if (atomic_cmpset_int(&swblk_zone_exhausted, 1, 0)) printf("swblk zone ok\n"); break; } if (nowait_noreplace) return (swapblk); VM_OBJECT_WUNLOCK(object); if (uma_zone_exhausted(swblk_zone)) { if (atomic_cmpset_int(&swblk_zone_exhausted, 0, 1)) printf("swap blk zone exhausted, " "increase kern.maxswzone\n"); vm_pageout_oom(VM_OOM_SWAPZ); pause("swzonxb", 10); } else uma_zwait(swblk_zone); VM_OBJECT_WLOCK(object); sb = swblk_iter_reinit(blks, object, pindex); if (sb != NULL) /* * Somebody swapped out a nearby page, * allocating swblk at the pindex index, * while we dropped the object lock. */ goto allocated; } for (;;) { error = swblk_iter_insert(blks, sb); if (error == 0) { if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1, 0)) printf("swpctrie zone ok\n"); break; } if (nowait_noreplace) { uma_zfree(swblk_zone, sb); return (swapblk); } VM_OBJECT_WUNLOCK(object); if (uma_zone_exhausted(swpctrie_zone)) { if (atomic_cmpset_int(&swpctrie_zone_exhausted, 0, 1)) printf("swap pctrie zone exhausted, " "increase kern.maxswzone\n"); vm_pageout_oom(VM_OOM_SWAPZ); pause("swzonxp", 10); } else uma_zwait(swpctrie_zone); VM_OBJECT_WLOCK(object); sb1 = swblk_iter_reinit(blks, object, pindex); if (sb1 != NULL) { uma_zfree(swblk_zone, sb); sb = sb1; goto allocated; } } } allocated: MPASS(sb->p == rounddown(pindex, SWAP_META_PAGES)); modpi = pindex % SWAP_META_PAGES; /* Return prior contents of metadata. */ prev_swapblk = sb->d[modpi]; if (!nowait_noreplace || prev_swapblk == SWAPBLK_NONE) { /* Enter block into metadata. */ sb->d[modpi] = swapblk; /* * Free the swblk if we end up with the empty page run. */ if (swapblk == SWAPBLK_NONE && swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { swblk_iter_remove(blks); uma_zfree(swblk_zone, sb); } } return (prev_swapblk); } /* * SWP_PAGER_META_TRANSFER() - transfer a range of blocks in the srcobject's * swap metadata into dstobject. * * Blocks in src that correspond to holes in dst are transferred. Blocks * in src that correspond to blocks in dst are freed. */ static void swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, vm_pindex_t pindex, vm_pindex_t count) { struct pctrie_iter dstblks, srcblks; struct page_range range; struct swblk *sb; daddr_t blk, d[SWAP_META_PAGES]; vm_pindex_t last; int d_mask, i, limit, start; _Static_assert(8 * sizeof(d_mask) >= SWAP_META_PAGES, "d_mask not big enough"); VM_OBJECT_ASSERT_WLOCKED(srcobject); VM_OBJECT_ASSERT_WLOCKED(dstobject); if (count == 0 || swblk_is_empty(srcobject)) return; swp_pager_init_freerange(&range); d_mask = 0; last = pindex + count; swblk_iter_init_only(&dstblks, dstobject); for (sb = swblk_iter_limit_init(&srcblks, srcobject, pindex, last), start = swblk_start(sb, pindex); sb != NULL; sb = swblk_iter_next(&srcblks), start = 0) { limit = MIN(last - srcblks.index, SWAP_META_PAGES); for (i = start; i < limit; i++) { if (sb->d[i] == SWAPBLK_NONE) continue; blk = swp_pager_meta_build(&dstblks, dstobject, srcblks.index + i - pindex, sb->d[i], true); if (blk == sb->d[i]) { /* * Failed memory allocation stopped transfer; * save this block for transfer with lock * released. */ d[i] = blk; d_mask |= 1 << i; } else if (blk != SWAPBLK_NONE) { /* Dst has a block at pindex, so free block. */ swp_pager_update_freerange(&range, sb->d[i]); } sb->d[i] = SWAPBLK_NONE; } if (swp_pager_swblk_empty(sb, 0, start) && swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { swblk_iter_remove(&srcblks); uma_zfree(swblk_zone, sb); } if (d_mask != 0) { /* Finish block transfer, with the lock released. */ VM_OBJECT_WUNLOCK(srcobject); do { i = ffs(d_mask) - 1; swp_pager_meta_build(&dstblks, dstobject, srcblks.index + i - pindex, d[i], false); d_mask &= ~(1 << i); } while (d_mask != 0); VM_OBJECT_WLOCK(srcobject); /* * While the lock was not held, the iterator path could * have become stale, so discard it. */ pctrie_iter_reset(&srcblks); } } swp_pager_freeswapspace(&range); } /* * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata * * Return freed swap blocks to the swap bitmap, and free emptied swblk * metadata. With 'freed' set, provide a count of freed blocks that were * not associated with valid resident pages. */ static void swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count, vm_size_t *freed) { struct pctrie_iter blks, pages; struct page_range range; struct swblk *sb; vm_page_t m; vm_pindex_t last; vm_size_t fc; int i, limit, start; VM_OBJECT_ASSERT_WLOCKED(object); fc = 0; if (count == 0 || swblk_is_empty(object)) goto out; swp_pager_init_freerange(&range); vm_page_iter_init(&pages, object); last = pindex + count; for (sb = swblk_iter_limit_init(&blks, object, pindex, last), start = swblk_start(sb, pindex); sb != NULL; sb = swblk_iter_next(&blks), start = 0) { limit = MIN(last - blks.index, SWAP_META_PAGES); for (i = start; i < limit; i++) { if (sb->d[i] == SWAPBLK_NONE) continue; swp_pager_update_freerange(&range, sb->d[i]); if (freed != NULL) { m = vm_radix_iter_lookup(&pages, blks.index + i); if (m == NULL || vm_page_none_valid(m)) fc++; } sb->d[i] = SWAPBLK_NONE; } if (swp_pager_swblk_empty(sb, 0, start) && swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { swblk_iter_remove(&blks); uma_zfree(swblk_zone, sb); } } swp_pager_freeswapspace(&range); out: if (freed != NULL) *freed = fc; } static void swp_pager_meta_free_block(struct swblk *sb, void *rangev) { struct page_range *range = rangev; for (int i = 0; i < SWAP_META_PAGES; i++) { if (sb->d[i] != SWAPBLK_NONE) swp_pager_update_freerange(range, sb->d[i]); } uma_zfree(swblk_zone, sb); } /* * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object * * This routine locates and destroys all swap metadata associated with * an object. */ static void swp_pager_meta_free_all(vm_object_t object) { struct page_range range; VM_OBJECT_ASSERT_WLOCKED(object); swp_pager_init_freerange(&range); SWAP_PCTRIE_RECLAIM_CALLBACK(&object->un_pager.swp.swp_blks, swp_pager_meta_free_block, &range); swp_pager_freeswapspace(&range); } /* * SWP_PAGER_METACTL() - misc control of swap meta data. * * This routine is capable of looking up, or removing swapblk * assignments in the swap meta data. It returns the swapblk being * looked-up, popped, or SWAPBLK_NONE if the block was invalid. * * When acting on a busy resident page and paging is in progress, we * have to wait until paging is complete but otherwise can act on the * busy page. */ static daddr_t swp_pager_meta_lookup(struct pctrie_iter *blks, vm_pindex_t pindex) { struct swblk *sb; sb = swblk_iter_lookup(blks, pindex); if (sb == NULL) return (SWAPBLK_NONE); return (sb->d[pindex % SWAP_META_PAGES]); } /* * Returns the least page index which is greater than or equal to the parameter * pindex and for which there is a swap block allocated. Returns OBJ_MAX_SIZE * if are no allocated swap blocks for the object after the requested pindex. */ static vm_pindex_t swap_pager_iter_find_least(struct pctrie_iter *blks, vm_pindex_t pindex) { struct swblk *sb; int i; if ((sb = swblk_iter_lookup_ge(blks, pindex)) == NULL) return (OBJ_MAX_SIZE); if (blks->index < pindex) { for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { if (sb->d[i] != SWAPBLK_NONE) return (blks->index + i); } if ((sb = swblk_iter_next(blks)) == NULL) return (OBJ_MAX_SIZE); } for (i = 0; i < SWAP_META_PAGES; i++) { if (sb->d[i] != SWAPBLK_NONE) return (blks->index + i); } /* * We get here if a swblk is present in the trie but it * doesn't map any blocks. */ MPASS(0); return (OBJ_MAX_SIZE); } /* * Find the first index >= pindex that has either a valid page or a swap * block. */ vm_pindex_t swap_pager_seek_data(vm_object_t object, vm_pindex_t pindex) { struct pctrie_iter blks, pages; vm_page_t m; vm_pindex_t swap_index; VM_OBJECT_ASSERT_RLOCKED(object); vm_page_iter_init(&pages, object); m = vm_radix_iter_lookup_ge(&pages, pindex); if (m != NULL && pages.index == pindex && vm_page_any_valid(m)) return (pages.index); swblk_iter_init_only(&blks, object); swap_index = swap_pager_iter_find_least(&blks, pindex); if (swap_index == pindex) return (swap_index); /* * Find the first resident page after m, before swap_index. */ while (m != NULL && pages.index < swap_index) { if (vm_page_any_valid(m)) return (pages.index); m = vm_radix_iter_step(&pages); } if (swap_index == OBJ_MAX_SIZE) swap_index = object->size; return (swap_index); } /* * Find the first index >= pindex that has neither a valid page nor a swap * block. */ vm_pindex_t swap_pager_seek_hole(vm_object_t object, vm_pindex_t pindex) { struct pctrie_iter blks, pages; struct swblk *sb; vm_page_t m; VM_OBJECT_ASSERT_RLOCKED(object); vm_page_iter_init(&pages, object); swblk_iter_init_only(&blks, object); while (((m = vm_radix_iter_lookup(&pages, pindex)) != NULL && vm_page_any_valid(m)) || ((sb = swblk_iter_lookup(&blks, pindex)) != NULL && sb->d[pindex % SWAP_META_PAGES] != SWAPBLK_NONE)) pindex++; return (pindex); } /* * Is every page in the backing object or swap shadowed in the parent, and * unbusy and valid in swap? */ bool swap_pager_scan_all_shadowed(vm_object_t object) { struct pctrie_iter backing_blks, backing_pages, blks, pages; vm_object_t backing_object; vm_page_t p, pp; vm_pindex_t backing_offset_index, new_pindex, pi, pi_ubound, ps, pv; VM_OBJECT_ASSERT_WLOCKED(object); VM_OBJECT_ASSERT_WLOCKED(object->backing_object); backing_object = object->backing_object; if ((backing_object->flags & OBJ_ANON) == 0) return (false); KASSERT((object->flags & OBJ_ANON) != 0, ("Shadow object is not anonymous")); backing_offset_index = OFF_TO_IDX(object->backing_object_offset); pi_ubound = MIN(backing_object->size, backing_offset_index + object->size); vm_page_iter_init(&pages, object); vm_page_iter_init(&backing_pages, backing_object); swblk_iter_init_only(&blks, object); swblk_iter_init_only(&backing_blks, backing_object); /* * Only check pages inside the parent object's range and inside the * parent object's mapping of the backing object. */ pv = ps = pi = backing_offset_index - 1; for (;;) { if (pi == pv) { p = vm_radix_iter_lookup_ge(&backing_pages, pv + 1); pv = p != NULL ? p->pindex : backing_object->size; } if (pi == ps) ps = swap_pager_iter_find_least(&backing_blks, ps + 1); pi = MIN(pv, ps); if (pi >= pi_ubound) break; if (pi == pv) { /* * If the backing object page is busy a grandparent or * older page may still be undergoing CoW. It is not * safe to collapse the backing object until it is * quiesced. */ if (vm_page_tryxbusy(p) == 0) return (false); /* * We raced with the fault handler that left newly * allocated invalid page on the object queue and * retried. */ if (!vm_page_all_valid(p)) break; /* * Busy of p disallows fault handler to validate parent * page (pp, below). */ } /* * See if the parent has the page or if the parent's object * pager has the page. If the parent has the page but the page * is not valid, the parent's object pager must have the page. * * If this fails, the parent does not completely shadow the * object and we might as well give up now. */ new_pindex = pi - backing_offset_index; pp = vm_radix_iter_lookup(&pages, new_pindex); /* * The valid check here is stable due to object lock being * required to clear valid and initiate paging. */ if ((pp == NULL || vm_page_none_valid(pp)) && !swp_pager_haspage_iter(new_pindex, NULL, NULL, &blks)) break; if (pi == pv) vm_page_xunbusy(p); } if (pi < pi_ubound) { if (pi == pv) vm_page_xunbusy(p); return (false); } return (true); } /* * System call swapon(name) enables swapping on device name, * which must be in the swdevsw. Return EBUSY * if already swapping on this device. */ #ifndef _SYS_SYSPROTO_H_ struct swapon_args { char *name; }; #endif int sys_swapon(struct thread *td, struct swapon_args *uap) { struct vattr attr; struct vnode *vp; struct nameidata nd; int error; error = priv_check(td, PRIV_SWAPON); if (error) return (error); sx_xlock(&swdev_syscall_lock); /* * Swap metadata may not fit in the KVM if we have physical * memory of >1GB. */ if (swblk_zone == NULL) { error = ENOMEM; goto done; } NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_USERSPACE, uap->name); error = namei(&nd); if (error) goto done; NDFREE_PNBUF(&nd); vp = nd.ni_vp; if (vn_isdisk_error(vp, &error)) { error = swapongeom(vp); } else if (vp->v_type == VREG && (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { /* * Allow direct swapping to NFS regular files in the same * way that nfs_mountroot() sets up diskless swapping. */ error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); } if (error != 0) vput(vp); else VOP_UNLOCK(vp); done: sx_xunlock(&swdev_syscall_lock); return (error); } /* * Check that the total amount of swap currently configured does not * exceed half the theoretical maximum. If it does, print a warning * message. */ static void swapon_check_swzone(void) { /* recommend using no more than half that amount */ if (swap_total > swap_maxpages / 2) { printf("warning: total configured swap (%lu pages) " "exceeds maximum recommended amount (%lu pages).\n", swap_total, swap_maxpages / 2); printf("warning: increase kern.maxswzone " "or reduce amount of swap.\n"); } } static int swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) { struct swdevt *sp, *tsp; daddr_t dvbase; /* * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. * First chop nblks off to page-align it, then convert. * * sw->sw_nblks is in page-sized chunks now too. */ nblks &= ~(ctodb(1) - 1); nblks = dbtoc(nblks); if (nblks == 0) return (EXTERROR(EINVAL, "swap device too small")); sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); sp->sw_blist = blist_create(nblks, M_WAITOK); sp->sw_vp = vp; sp->sw_id = id; sp->sw_dev = dev; sp->sw_nblks = nblks; sp->sw_used = 0; sp->sw_strategy = strategy; sp->sw_close = close; sp->sw_flags = flags; /* * Do not free the first blocks in order to avoid overwriting * any bsd label at the front of the partition */ blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), nblks - howmany(BBSIZE, PAGE_SIZE)); dvbase = 0; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(tsp, &swtailq, sw_list) { if (tsp->sw_end >= dvbase) { /* * We put one uncovered page between the devices * in order to definitively prevent any cross-device * I/O requests */ dvbase = tsp->sw_end + 1; } } sp->sw_first = dvbase; sp->sw_end = dvbase + nblks; TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); nswapdev++; swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); swap_total += nblks; swapon_check_swzone(); swp_sizecheck(); mtx_unlock(&sw_dev_mtx); EVENTHANDLER_INVOKE(swapon, sp); return (0); } /* * SYSCALL: swapoff(devname) * * Disable swapping on the given device. * * XXX: Badly designed system call: it should use a device index * rather than filename as specification. We keep sw_vp around * only to make this work. */ static int kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg, u_int flags) { struct vnode *vp; struct nameidata nd; struct swdevt *sp; int error; error = priv_check(td, PRIV_SWAPOFF); if (error != 0) return (error); if ((flags & ~(SWAPOFF_FORCE)) != 0) return (EINVAL); sx_xlock(&swdev_syscall_lock); NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name); error = namei(&nd); if (error) goto done; NDFREE_PNBUF(&nd); vp = nd.ni_vp; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_vp == vp) break; } mtx_unlock(&sw_dev_mtx); if (sp == NULL) { error = EINVAL; goto done; } error = swapoff_one(sp, td->td_ucred, flags); done: sx_xunlock(&swdev_syscall_lock); return (error); } #ifdef COMPAT_FREEBSD13 int freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap) { return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0)); } #endif int sys_swapoff(struct thread *td, struct swapoff_args *uap) { return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags)); } static int swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags) { u_long nblks; #ifdef MAC int error; #endif sx_assert(&swdev_syscall_lock, SA_XLOCKED); #ifdef MAC (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); error = mac_system_check_swapoff(cred, sp->sw_vp); (void) VOP_UNLOCK(sp->sw_vp); if (error != 0) return (error); #endif nblks = sp->sw_nblks; /* * We can turn off this swap device safely only if the * available virtual memory in the system will fit the amount * of data we will have to page back in, plus an epsilon so * the system doesn't become critically low on swap space. * The vm_free_count() part does not account e.g. for clean * pages that can be immediately reclaimed without paging, so * this is a very rough estimation. * * On the other hand, not turning swap off on swapoff_all() * means that we can lose swap data when filesystems go away, * which is arguably worse. */ if ((flags & SWAPOFF_FORCE) == 0 && vm_free_count() + swap_pager_avail < nblks + nswap_lowat) return (ENOMEM); /* * Prevent further allocations on this device. */ mtx_lock(&sw_dev_mtx); sp->sw_flags |= SW_CLOSING; swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); swap_total -= nblks; mtx_unlock(&sw_dev_mtx); /* * Page in the contents of the device and close it. */ swap_pager_swapoff(sp); sp->sw_close(curthread, sp); mtx_lock(&sw_dev_mtx); sp->sw_id = NULL; TAILQ_REMOVE(&swtailq, sp, sw_list); nswapdev--; if (nswapdev == 0) swap_pager_full = swap_pager_almost_full = true; if (swdevhd == sp) swdevhd = NULL; mtx_unlock(&sw_dev_mtx); blist_destroy(sp->sw_blist); free(sp, M_VMPGDATA); return (0); } void swapoff_all(void) { struct swdevt *sp, *spt; const char *devname; int error; sx_xlock(&swdev_syscall_lock); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { mtx_unlock(&sw_dev_mtx); if (vn_isdisk(sp->sw_vp)) devname = devtoname(sp->sw_vp->v_rdev); else devname = "[file]"; error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE); if (error != 0) { printf("Cannot remove swap device %s (error=%d), " "skipping.\n", devname, error); } else if (bootverbose) { printf("Swap device %s removed.\n", devname); } mtx_lock(&sw_dev_mtx); } mtx_unlock(&sw_dev_mtx); sx_xunlock(&swdev_syscall_lock); } void swap_pager_status(int *total, int *used) { *total = swap_total; *used = swap_total - swap_pager_avail - nswapdev * howmany(BBSIZE, PAGE_SIZE); } int swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) { struct swdevt *sp; const char *tmp_devname; int error, n; n = 0; error = ENOENT; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (n != name) { n++; continue; } xs->xsw_version = XSWDEV_VERSION; xs->xsw_dev = sp->sw_dev; xs->xsw_flags = sp->sw_flags; xs->xsw_nblks = sp->sw_nblks; xs->xsw_used = sp->sw_used; if (devname != NULL) { if (vn_isdisk(sp->sw_vp)) tmp_devname = devtoname(sp->sw_vp->v_rdev); else tmp_devname = "[file]"; strncpy(devname, tmp_devname, len); } error = 0; break; } mtx_unlock(&sw_dev_mtx); return (error); } #if defined(COMPAT_FREEBSD11) #define XSWDEV_VERSION_11 1 struct xswdev11 { u_int xsw_version; uint32_t xsw_dev; int xsw_flags; int xsw_nblks; int xsw_used; }; #endif #if defined(__amd64__) && defined(COMPAT_FREEBSD32) struct xswdev32 { u_int xsw_version; u_int xsw_dev1, xsw_dev2; int xsw_flags; int xsw_nblks; int xsw_used; }; #endif static int sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) { struct xswdev xs; #if defined(__amd64__) && defined(COMPAT_FREEBSD32) struct xswdev32 xs32; #endif #if defined(COMPAT_FREEBSD11) struct xswdev11 xs11; #endif int error; if (arg2 != 1) /* name length */ return (EINVAL); memset(&xs, 0, sizeof(xs)); error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); if (error != 0) return (error); #if defined(__amd64__) && defined(COMPAT_FREEBSD32) if (req->oldlen == sizeof(xs32)) { memset(&xs32, 0, sizeof(xs32)); xs32.xsw_version = XSWDEV_VERSION; xs32.xsw_dev1 = xs.xsw_dev; xs32.xsw_dev2 = xs.xsw_dev >> 32; xs32.xsw_flags = xs.xsw_flags; xs32.xsw_nblks = xs.xsw_nblks; xs32.xsw_used = xs.xsw_used; error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); return (error); } #endif #if defined(COMPAT_FREEBSD11) if (req->oldlen == sizeof(xs11)) { memset(&xs11, 0, sizeof(xs11)); xs11.xsw_version = XSWDEV_VERSION_11; xs11.xsw_dev = xs.xsw_dev; /* truncation */ xs11.xsw_flags = xs.xsw_flags; xs11.xsw_nblks = xs.xsw_nblks; xs11.xsw_used = xs.xsw_used; error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); return (error); } #endif error = SYSCTL_OUT(req, &xs, sizeof(xs)); return (error); } SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, "Number of swap devices"); SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, sysctl_vm_swap_info, "Swap statistics by device"); /* * Count the approximate swap usage in pages for a vmspace. The * shadowed or not yet copied on write swap blocks are not accounted. * The map must be locked. */ long vmspace_swap_count(struct vmspace *vmspace) { struct pctrie_iter blks; vm_map_t map; vm_map_entry_t cur; vm_object_t object; struct swblk *sb; vm_pindex_t e, pi; long count; int i, limit, start; map = &vmspace->vm_map; count = 0; VM_MAP_ENTRY_FOREACH(cur, map) { if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) continue; object = cur->object.vm_object; if (object == NULL || (object->flags & OBJ_SWAP) == 0) continue; VM_OBJECT_RLOCK(object); if ((object->flags & OBJ_SWAP) == 0) goto unlock; pi = OFF_TO_IDX(cur->offset); e = pi + OFF_TO_IDX(cur->end - cur->start); for (sb = swblk_iter_limit_init(&blks, object, pi, e), start = swblk_start(sb, pi); sb != NULL; sb = swblk_iter_next(&blks), start = 0) { limit = MIN(e - blks.index, SWAP_META_PAGES); for (i = start; i < limit; i++) { if (sb->d[i] != SWAPBLK_NONE) count++; } } unlock: VM_OBJECT_RUNLOCK(object); } return (count); } /* * GEOM backend * * Swapping onto disk devices. * */ static g_orphan_t swapgeom_orphan; static struct g_class g_swap_class = { .name = "SWAP", .version = G_VERSION, .orphan = swapgeom_orphan, }; DECLARE_GEOM_CLASS(g_swap_class, g_class); static void swapgeom_close_ev(void *arg, int flags) { struct g_consumer *cp; cp = arg; g_access(cp, -1, -1, 0); g_detach(cp); g_destroy_consumer(cp); } /* * Add a reference to the g_consumer for an inflight transaction. */ static void swapgeom_acquire(struct g_consumer *cp) { mtx_assert(&sw_dev_mtx, MA_OWNED); cp->index++; } /* * Remove a reference from the g_consumer. Post a close event if all * references go away, since the function might be called from the * biodone context. */ static void swapgeom_release(struct g_consumer *cp, struct swdevt *sp) { mtx_assert(&sw_dev_mtx, MA_OWNED); cp->index--; if (cp->index == 0) { if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) sp->sw_id = NULL; } } static void swapgeom_done(struct bio *bp2) { struct swdevt *sp; struct buf *bp; struct g_consumer *cp; bp = bp2->bio_caller2; cp = bp2->bio_from; bp->b_ioflags = bp2->bio_flags; if (bp2->bio_error) bp->b_ioflags |= BIO_ERROR; bp->b_resid = bp->b_bcount - bp2->bio_completed; bp->b_error = bp2->bio_error; bp->b_caller1 = NULL; bufdone(bp); sp = bp2->bio_caller1; mtx_lock(&sw_dev_mtx); swapgeom_release(cp, sp); mtx_unlock(&sw_dev_mtx); g_destroy_bio(bp2); } static void swapgeom_strategy(struct buf *bp, struct swdevt *sp) { struct bio *bio; struct g_consumer *cp; mtx_lock(&sw_dev_mtx); cp = sp->sw_id; if (cp == NULL) { mtx_unlock(&sw_dev_mtx); bp->b_error = ENXIO; bp->b_ioflags |= BIO_ERROR; bufdone(bp); return; } swapgeom_acquire(cp); mtx_unlock(&sw_dev_mtx); if (bp->b_iocmd == BIO_WRITE) bio = g_new_bio(); else bio = g_alloc_bio(); if (bio == NULL) { mtx_lock(&sw_dev_mtx); swapgeom_release(cp, sp); mtx_unlock(&sw_dev_mtx); bp->b_error = ENOMEM; bp->b_ioflags |= BIO_ERROR; printf("swap_pager: cannot allocate bio\n"); bufdone(bp); return; } bp->b_caller1 = bio; bio->bio_caller1 = sp; bio->bio_caller2 = bp; bio->bio_cmd = bp->b_iocmd; bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; bio->bio_length = bp->b_bcount; bio->bio_done = swapgeom_done; bio->bio_flags |= BIO_SWAP; if (!buf_mapped(bp)) { bio->bio_ma = bp->b_pages; bio->bio_data = unmapped_buf; bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; bio->bio_ma_n = bp->b_npages; bio->bio_flags |= BIO_UNMAPPED; } else { bio->bio_data = bp->b_data; bio->bio_ma = NULL; } g_io_request(bio, cp); return; } static void swapgeom_orphan(struct g_consumer *cp) { struct swdevt *sp; int destroy; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_id == cp) { sp->sw_flags |= SW_CLOSING; break; } } /* * Drop reference we were created with. Do directly since we're in a * special context where we don't have to queue the call to * swapgeom_close_ev(). */ cp->index--; destroy = ((sp != NULL) && (cp->index == 0)); if (destroy) sp->sw_id = NULL; mtx_unlock(&sw_dev_mtx); if (destroy) swapgeom_close_ev(cp, 0); } static void swapgeom_close(struct thread *td, struct swdevt *sw) { struct g_consumer *cp; mtx_lock(&sw_dev_mtx); cp = sw->sw_id; sw->sw_id = NULL; mtx_unlock(&sw_dev_mtx); /* * swapgeom_close() may be called from the biodone context, * where we cannot perform topology changes. Delegate the * work to the events thread. */ if (cp != NULL) g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); } static int swapongeom_locked(struct cdev *dev, struct vnode *vp) { struct g_provider *pp; struct g_consumer *cp; static struct g_geom *gp; struct swdevt *sp; u_long nblks; int error; pp = g_dev_getprovider(dev); if (pp == NULL) return (ENODEV); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { cp = sp->sw_id; if (cp != NULL && cp->provider == pp) { mtx_unlock(&sw_dev_mtx); return (EBUSY); } } mtx_unlock(&sw_dev_mtx); if (gp == NULL) gp = g_new_geomf(&g_swap_class, "swap"); cp = g_new_consumer(gp); cp->index = 1; /* Number of active I/Os, plus one for being active. */ cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; g_attach(cp, pp); /* * XXX: Every time you think you can improve the margin for * footshooting, somebody depends on the ability to do so: * savecore(8) wants to write to our swapdev so we cannot * set an exclusive count :-( */ error = g_access(cp, 1, 1, 0); if (error == 0) { nblks = pp->mediasize / DEV_BSIZE; error = swaponsomething(vp, cp, nblks, swapgeom_strategy, swapgeom_close, dev2udev(dev), (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); if (error != 0) g_access(cp, -1, -1, 0); } if (error != 0) { g_detach(cp); g_destroy_consumer(cp); } return (error); } static int swapongeom(struct vnode *vp) { int error; ASSERT_VOP_ELOCKED(vp, "swapongeom"); if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { error = ENOENT; } else { g_topology_lock(); error = swapongeom_locked(vp->v_rdev, vp); g_topology_unlock(); } return (error); } /* * VNODE backend * * This is used mainly for network filesystem (read: probably only tested * with NFS) swapfiles. * */ static void swapdev_strategy(struct buf *bp, struct swdevt *sp) { struct vnode *vp2; bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); vp2 = sp->sw_id; vhold(vp2); if (bp->b_iocmd == BIO_WRITE) { vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); if (bp->b_bufobj) bufobj_wdrop(bp->b_bufobj); bufobj_wref(&vp2->v_bufobj); } else { vn_lock(vp2, LK_SHARED | LK_RETRY); } if (bp->b_bufobj != &vp2->v_bufobj) bp->b_bufobj = &vp2->v_bufobj; bp->b_vp = vp2; bp->b_iooffset = dbtob(bp->b_blkno); bstrategy(bp); VOP_UNLOCK(vp2); } static void swapdev_close(struct thread *td, struct swdevt *sp) { struct vnode *vp; vp = sp->sw_vp; vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); vput(vp); } static int swaponvp(struct thread *td, struct vnode *vp, u_long nblks) { struct swdevt *sp; int error; ASSERT_VOP_ELOCKED(vp, "swaponvp"); if (nblks == 0) return (ENXIO); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_id == vp) { mtx_unlock(&sw_dev_mtx); return (EBUSY); } } mtx_unlock(&sw_dev_mtx); #ifdef MAC error = mac_system_check_swapon(td->td_ucred, vp); if (error == 0) #endif error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); if (error != 0) return (error); error = swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, NODEV, 0); if (error != 0) VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); return (error); } static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) { int error, new, n; new = nsw_wcount_async_max; error = sysctl_handle_int(oidp, &new, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (new > nswbuf / 2 || new < 1) return (EINVAL); mtx_lock(&swbuf_mtx); while (nsw_wcount_async_max != new) { /* * Adjust difference. If the current async count is too low, * we will need to sqeeze our update slowly in. Sleep with a * higher priority than getpbuf() to finish faster. */ n = new - nsw_wcount_async_max; if (nsw_wcount_async + n >= 0) { nsw_wcount_async += n; nsw_wcount_async_max += n; wakeup(&nsw_wcount_async); } else { nsw_wcount_async_max -= nsw_wcount_async; nsw_wcount_async = 0; msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, "swpsysctl", 0); } } mtx_unlock(&swbuf_mtx); return (0); } static void swap_pager_update_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end) { VM_OBJECT_WLOCK(object); KASSERT((object->flags & OBJ_ANON) == 0, ("Splittable object with writecount")); object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; VM_OBJECT_WUNLOCK(object); } static void swap_pager_release_writecount(vm_object_t object, vm_offset_t start, vm_offset_t end) { VM_OBJECT_WLOCK(object); KASSERT((object->flags & OBJ_ANON) == 0, ("Splittable object with writecount")); KASSERT(object->un_pager.swp.writemappings >= (vm_ooffset_t)end - start, ("swap obj %p writecount %jx dec %jx", object, (uintmax_t)object->un_pager.swp.writemappings, (uintmax_t)((vm_ooffset_t)end - start))); object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; VM_OBJECT_WUNLOCK(object); } diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h index 3287886026f7..da1457762c0b 100644 --- a/sys/vm/swap_pager.h +++ b/sys/vm/swap_pager.h @@ -1,91 +1,92 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1990 University of Utah. * Copyright (c) 1991 The Regents of the University of California. * All rights reserved. * * This code is derived from software contributed to Berkeley by * the Systems Programming Group of the University of Utah Computer * Science Department. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef _VM_SWAP_PAGER_H_ #define _VM_SWAP_PAGER_H_ #include struct buf; struct swdevt; struct thread; typedef void sw_strategy_t(struct buf *, struct swdevt *); typedef void sw_close_t(struct thread *, struct swdevt *); /* * Swap device table */ struct swdevt { int sw_flags; int sw_nblks; int sw_used; dev_t sw_dev; struct vnode *sw_vp; void *sw_id; __daddr_t sw_first; __daddr_t sw_end; struct blist *sw_blist; TAILQ_ENTRY(swdevt) sw_list; sw_strategy_t *sw_strategy; sw_close_t *sw_close; }; #define SW_UNMAPPED 0x01 #define SW_CLOSING 0x04 #ifdef _KERNEL +extern bool swap_pager_almost_full; extern int swap_pager_avail; extern int nsw_cluster_max; struct xswdev; int swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len); void swap_pager_copy(vm_object_t, vm_object_t, vm_pindex_t, int); bool swap_pager_scan_all_shadowed(vm_object_t object); vm_pindex_t swap_pager_seek_data(vm_object_t object, vm_pindex_t pindex); vm_pindex_t swap_pager_seek_hole(vm_object_t object, vm_pindex_t pindex); void swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size, vm_size_t *freed); void swap_pager_swap_init(void); int swap_pager_nswapdev(void); int swap_pager_reserve(vm_object_t, vm_pindex_t, vm_pindex_t); void swap_pager_status(int *total, int *used); u_long swap_pager_swapped_pages(vm_object_t object); void swapoff_all(void); bool swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, vm_ooffset_t size, vm_ooffset_t offset); #endif /* _KERNEL */ #endif /* _VM_SWAP_PAGER_H_ */ diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c index b500eb8156bc..3f1be78342c9 100644 --- a/sys/vm/vm_pageout.c +++ b/sys/vm/vm_pageout.c @@ -1,2416 +1,2449 @@ /*- * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) * * Copyright (c) 1991 Regents of the University of California. * All rights reserved. * Copyright (c) 1994 John S. Dyson * All rights reserved. * Copyright (c) 1994 David Greenman * All rights reserved. * Copyright (c) 2005 Yahoo! Technologies Norway AS * All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Authors: Avadis Tevanian, Jr., Michael Wayne Young * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ /* * The proverbial page-out daemon. */ #include #include "opt_vm.h" #include #include #include #include #include +#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * System initialization */ /* the kernel process "vm_pageout"*/ static void vm_pageout(void); static void vm_pageout_init(void); static int vm_pageout_clean(vm_page_t m, int *numpagedout); static int vm_pageout_cluster(vm_page_t m); static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage, int starting_page_shortage); SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, NULL); struct proc *pageproc; static struct kproc_desc page_kp = { "pagedaemon", vm_pageout, &pageproc }; SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &page_kp); SDT_PROVIDER_DEFINE(vm); SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); /* Pagedaemon activity rates, in subdivisions of one second. */ #define VM_LAUNDER_RATE 10 #define VM_INACT_SCAN_RATE 10 static int swapdev_enabled; int vm_pageout_page_count = 32; static int vm_panic_on_oom = 0; SYSCTL_INT(_vm, OID_AUTO, panic_on_oom, CTLFLAG_RWTUN, &vm_panic_on_oom, 0, "Panic on the given number of out-of-memory errors instead of " "killing the largest process"); static int vm_pageout_update_period; SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, CTLFLAG_RWTUN, &vm_pageout_update_period, 0, "Maximum active LRU update period"); static int pageout_cpus_per_thread = 16; SYSCTL_INT(_vm, OID_AUTO, pageout_cpus_per_thread, CTLFLAG_RDTUN, &pageout_cpus_per_thread, 0, "Number of CPUs per pagedaemon worker thread"); static int lowmem_period = 10; SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RWTUN, &lowmem_period, 0, "Low memory callback period"); static int disable_swap_pageouts; SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, CTLFLAG_RWTUN, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); static int pageout_lock_miss; SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); static int vm_pageout_oom_seq = 12; SYSCTL_INT(_vm, OID_AUTO, pageout_oom_seq, CTLFLAG_RWTUN, &vm_pageout_oom_seq, 0, "back-to-back calls to oom detector to start OOM"); -static int act_scan_laundry_weight = 3; - static int -sysctl_act_scan_laundry_weight(SYSCTL_HANDLER_ARGS) +sysctl_laundry_weight(SYSCTL_HANDLER_ARGS) { - int error, newval; + int error, val; - newval = act_scan_laundry_weight; - error = sysctl_handle_int(oidp, &newval, 0, req); - if (error || req->newptr == NULL) + val = *(int *)arg1; + error = sysctl_handle_int(oidp, &val, 0, req); + if (error != 0 || req->newptr == NULL) return (error); - if (newval < 1) + if (val < arg2 || val > 100) return (EINVAL); - act_scan_laundry_weight = newval; + *(int *)arg1 = val; return (0); } -SYSCTL_PROC(_vm, OID_AUTO, act_scan_laundry_weight, CTLFLAG_RWTUN | CTLTYPE_INT, - &act_scan_laundry_weight, 0, sysctl_act_scan_laundry_weight, "I", + +static int act_scan_laundry_weight = 3; +SYSCTL_PROC(_vm, OID_AUTO, act_scan_laundry_weight, + CTLTYPE_INT | CTLFLAG_RWTUN, &act_scan_laundry_weight, 1, + sysctl_laundry_weight, "I", "weight given to clean vs. dirty pages in active queue scans"); +static int inact_scan_laundry_weight = 1; +SYSCTL_PROC(_vm, OID_AUTO, inact_scan_laundry_weight, + CTLTYPE_INT | CTLFLAG_RWTUN, &inact_scan_laundry_weight, 0, + sysctl_laundry_weight, "I", + "weight given to clean vs. dirty pages in inactive queue scans"); + static u_int vm_background_launder_rate = 4096; SYSCTL_UINT(_vm, OID_AUTO, background_launder_rate, CTLFLAG_RWTUN, &vm_background_launder_rate, 0, "background laundering rate, in kilobytes per second"); static u_int vm_background_launder_max = 20 * 1024; SYSCTL_UINT(_vm, OID_AUTO, background_launder_max, CTLFLAG_RWTUN, &vm_background_launder_max, 0, "background laundering cap, in kilobytes"); u_long vm_page_max_user_wired; SYSCTL_ULONG(_vm, OID_AUTO, max_user_wired, CTLFLAG_RW, &vm_page_max_user_wired, 0, "system-wide limit to user-wired page count"); static u_int isqrt(u_int num); static int vm_pageout_launder(struct vm_domain *vmd, int launder, bool in_shortfall); static void vm_pageout_laundry_worker(void *arg); struct scan_state { struct vm_batchqueue bq; struct vm_pagequeue *pq; vm_page_t marker; int maxscan; int scanned; }; static void vm_pageout_init_scan(struct scan_state *ss, struct vm_pagequeue *pq, vm_page_t marker, vm_page_t after, int maxscan) { vm_pagequeue_assert_locked(pq); KASSERT((marker->a.flags & PGA_ENQUEUED) == 0, ("marker %p already enqueued", marker)); if (after == NULL) TAILQ_INSERT_HEAD(&pq->pq_pl, marker, plinks.q); else TAILQ_INSERT_AFTER(&pq->pq_pl, after, marker, plinks.q); vm_page_aflag_set(marker, PGA_ENQUEUED); vm_batchqueue_init(&ss->bq); ss->pq = pq; ss->marker = marker; ss->maxscan = maxscan; ss->scanned = 0; vm_pagequeue_unlock(pq); } static void vm_pageout_end_scan(struct scan_state *ss) { struct vm_pagequeue *pq; pq = ss->pq; vm_pagequeue_assert_locked(pq); KASSERT((ss->marker->a.flags & PGA_ENQUEUED) != 0, ("marker %p not enqueued", ss->marker)); TAILQ_REMOVE(&pq->pq_pl, ss->marker, plinks.q); vm_page_aflag_clear(ss->marker, PGA_ENQUEUED); pq->pq_pdpages += ss->scanned; } /* * Add a small number of queued pages to a batch queue for later processing * without the corresponding queue lock held. The caller must have enqueued a * marker page at the desired start point for the scan. Pages will be * physically dequeued if the caller so requests. Otherwise, the returned * batch may contain marker pages, and it is up to the caller to handle them. * * When processing the batch queue, vm_pageout_defer() must be used to * determine whether the page has been logically dequeued since the batch was * collected. */ static __always_inline void vm_pageout_collect_batch(struct scan_state *ss, const bool dequeue) { struct vm_pagequeue *pq; vm_page_t m, marker, n; marker = ss->marker; pq = ss->pq; KASSERT((marker->a.flags & PGA_ENQUEUED) != 0, ("marker %p not enqueued", ss->marker)); vm_pagequeue_lock(pq); for (m = TAILQ_NEXT(marker, plinks.q); m != NULL && ss->scanned < ss->maxscan && ss->bq.bq_cnt < VM_BATCHQUEUE_SIZE; m = n, ss->scanned++) { n = TAILQ_NEXT(m, plinks.q); if ((m->flags & PG_MARKER) == 0) { KASSERT((m->a.flags & PGA_ENQUEUED) != 0, ("page %p not enqueued", m)); KASSERT((m->flags & PG_FICTITIOUS) == 0, ("Fictitious page %p cannot be in page queue", m)); KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("Unmanaged page %p cannot be in page queue", m)); } else if (dequeue) continue; (void)vm_batchqueue_insert(&ss->bq, m); if (dequeue) { TAILQ_REMOVE(&pq->pq_pl, m, plinks.q); vm_page_aflag_clear(m, PGA_ENQUEUED); } } TAILQ_REMOVE(&pq->pq_pl, marker, plinks.q); if (__predict_true(m != NULL)) TAILQ_INSERT_BEFORE(m, marker, plinks.q); else TAILQ_INSERT_TAIL(&pq->pq_pl, marker, plinks.q); if (dequeue) vm_pagequeue_cnt_add(pq, -ss->bq.bq_cnt); vm_pagequeue_unlock(pq); } /* * Return the next page to be scanned, or NULL if the scan is complete. */ static __always_inline vm_page_t vm_pageout_next(struct scan_state *ss, const bool dequeue) { if (ss->bq.bq_cnt == 0) vm_pageout_collect_batch(ss, dequeue); return (vm_batchqueue_pop(&ss->bq)); } /* * Determine whether processing of a page should be deferred and ensure that any * outstanding queue operations are processed. */ static __always_inline bool vm_pageout_defer(vm_page_t m, const uint8_t queue, const bool enqueued) { vm_page_astate_t as; as = vm_page_astate_load(m); if (__predict_false(as.queue != queue || ((as.flags & PGA_ENQUEUED) != 0) != enqueued)) return (true); if ((as.flags & PGA_QUEUE_OP_MASK) != 0) { vm_page_pqbatch_submit(m, queue); return (true); } return (false); } /* * We can cluster only if the page is not clean, busy, or held, and the page is * in the laundry queue. */ static bool vm_pageout_flushable(vm_page_t m) { if (vm_page_tryxbusy(m) == 0) return (false); if (!vm_page_wired(m)) { vm_page_test_dirty(m); if (m->dirty != 0 && vm_page_in_laundry(m) && vm_page_try_remove_write(m)) return (true); } vm_page_xunbusy(m); return (false); } /* * Scan for pages at adjacent offsets within the given page's object that are * eligible for laundering, form a cluster of these pages and the given page, * and launder that cluster. */ static int vm_pageout_cluster(vm_page_t m) { struct pctrie_iter pages; vm_page_t mc[2 * vm_pageout_page_count - 1]; int alignment, page_base, pageout_count; VM_OBJECT_ASSERT_WLOCKED(m->object); vm_page_assert_xbusied(m); vm_page_iter_init(&pages, m->object); alignment = m->pindex % vm_pageout_page_count; page_base = nitems(mc) / 2; pageout_count = 1; mc[page_base] = m; /* * During heavy mmap/modification loads the pageout * daemon can really fragment the underlying file * due to flushing pages out of order and not trying to * align the clusters (which leaves sporadic out-of-order * holes). To solve this problem we do the reverse scan * first and attempt to align our cluster, then do a * forward scan if room remains. * * If we are at an alignment boundary, stop here, and switch directions. */ if (alignment > 0) { pages.index = mc[page_base]->pindex; do { m = vm_radix_iter_prev(&pages); if (m == NULL || !vm_pageout_flushable(m)) break; mc[--page_base] = m; } while (pageout_count++ < alignment); } if (pageout_count < vm_pageout_page_count) { pages.index = mc[page_base + pageout_count - 1]->pindex; do { m = vm_radix_iter_next(&pages); if (m == NULL || !vm_pageout_flushable(m)) break; mc[page_base + pageout_count] = m; } while (++pageout_count < vm_pageout_page_count); } if (pageout_count < vm_pageout_page_count && alignment == nitems(mc) / 2 - page_base) { /* Resume the reverse scan. */ pages.index = mc[page_base]->pindex; do { m = vm_radix_iter_prev(&pages); if (m == NULL || !vm_pageout_flushable(m)) break; mc[--page_base] = m; } while (++pageout_count < vm_pageout_page_count); } return (vm_pageout_flush(&mc[page_base], pageout_count, VM_PAGER_PUT_NOREUSE, NULL)); } /* * vm_pageout_flush() - launder the given pages * * The given pages are laundered. Note that we setup for the start of * I/O ( i.e. busy the page ), mark it read-only, and bump the object * reference count all in here rather then in the parent. If we want * the parent to do more sophisticated things we may have to change * the ordering. * * If eio is not NULL, returns the count of pages between 0 and first page * with status VM_PAGER_AGAIN. *eio is set to true if pager returned * VM_PAGER_ERROR or VM_PAGER_FAIL for any page in that set. * * Otherwise, returns the number of paged-out pages. */ int vm_pageout_flush(vm_page_t *mc, int count, int flags, bool *eio) { vm_object_t object = mc[0]->object; int pageout_status[count]; int numpagedout = 0; int i, runlen; VM_OBJECT_ASSERT_WLOCKED(object); /* * Initiate I/O. Mark the pages shared busy and verify that they're * valid and read-only. * * We do not have to fixup the clean/dirty bits here... we can * allow the pager to do it after the I/O completes. * * NOTE! mc[i]->dirty may be partial or fragmented due to an * edge case with file fragments. */ for (i = 0; i < count; i++) { KASSERT(vm_page_all_valid(mc[i]), ("vm_pageout_flush: partially invalid page %p index %d/%d", mc[i], i, count)); KASSERT((mc[i]->a.flags & PGA_WRITEABLE) == 0, ("vm_pageout_flush: writeable page %p", mc[i])); vm_page_busy_downgrade(mc[i]); } vm_object_pip_add(object, count); vm_pager_put_pages(object, mc, count, flags, pageout_status); runlen = count; if (eio != NULL) *eio = false; for (i = 0; i < count; i++) { vm_page_t mt = mc[i]; KASSERT(pageout_status[i] == VM_PAGER_PEND || !pmap_page_is_write_mapped(mt), ("vm_pageout_flush: page %p is not write protected", mt)); switch (pageout_status[i]) { case VM_PAGER_OK: /* * The page may have moved since laundering started, in * which case it should be left alone. */ if (vm_page_in_laundry(mt)) vm_page_deactivate_noreuse(mt); /* FALLTHROUGH */ case VM_PAGER_PEND: numpagedout++; break; case VM_PAGER_BAD: /* * The page is outside the object's range. We pretend * that the page out worked and clean the page, so the * changes will be lost if the page is reclaimed by * the page daemon. */ vm_page_undirty(mt); if (vm_page_in_laundry(mt)) vm_page_deactivate_noreuse(mt); break; case VM_PAGER_ERROR: case VM_PAGER_FAIL: /* * If the page couldn't be paged out to swap because the * pager wasn't able to find space, place the page in * the PQ_UNSWAPPABLE holding queue. This is an * optimization that prevents the page daemon from * wasting CPU cycles on pages that cannot be reclaimed * because no swap device is configured. * * Otherwise, reactivate the page so that it doesn't * clog the laundry and inactive queues. (We will try * paging it out again later.) */ if ((object->flags & OBJ_SWAP) != 0 && pageout_status[i] == VM_PAGER_FAIL) { vm_page_unswappable(mt); numpagedout++; } else vm_page_activate(mt); if (eio != NULL) *eio = true; break; case VM_PAGER_AGAIN: if (runlen == count) runlen = i; break; } /* * If the operation is still going, leave the page busy to * block all other accesses. Also, leave the paging in * progress indicator set so that we don't attempt an object * collapse. */ if (pageout_status[i] != VM_PAGER_PEND) { vm_object_pip_wakeup(object); vm_page_sunbusy(mt); } } if (eio != NULL) return (runlen); return (numpagedout); } static void vm_pageout_swapon(void *arg __unused, struct swdevt *sp __unused) { atomic_store_rel_int(&swapdev_enabled, 1); } static void vm_pageout_swapoff(void *arg __unused, struct swdevt *sp __unused) { if (swap_pager_nswapdev() == 1) atomic_store_rel_int(&swapdev_enabled, 0); } /* * Attempt to acquire all of the necessary locks to launder a page and * then call through the clustering layer to PUTPAGES. Wait a short * time for a vnode lock. * * Requires the page and object lock on entry, releases both before return. * Returns 0 on success and an errno otherwise. */ static int vm_pageout_clean(vm_page_t m, int *numpagedout) { struct vnode *vp; struct mount *mp; vm_object_t object; vm_pindex_t pindex; int error; object = m->object; VM_OBJECT_ASSERT_WLOCKED(object); error = 0; vp = NULL; mp = NULL; /* * The object is already known NOT to be dead. It * is possible for the vget() to block the whole * pageout daemon, but the new low-memory handling * code should prevent it. * * We can't wait forever for the vnode lock, we might * deadlock due to a vn_read() getting stuck in * vm_wait while holding this vnode. We skip the * vnode if we can't get it in a reasonable amount * of time. */ if (object->type == OBJT_VNODE) { vm_page_xunbusy(m); vp = object->handle; if (vp->v_type == VREG && vn_start_write(vp, &mp, V_NOWAIT) != 0) { mp = NULL; error = EDEADLK; goto unlock_all; } KASSERT(mp != NULL, ("vp %p with NULL v_mount", vp)); vm_object_reference_locked(object); pindex = m->pindex; VM_OBJECT_WUNLOCK(object); if (vget(vp, vn_lktype_write(NULL, vp) | LK_TIMELOCK) != 0) { vp = NULL; error = EDEADLK; goto unlock_mp; } VM_OBJECT_WLOCK(object); /* * Ensure that the object and vnode were not disassociated * while locks were dropped. */ if (vp->v_object != object) { error = ENOENT; goto unlock_all; } /* * While the object was unlocked, the page may have been: * (1) moved to a different queue, * (2) reallocated to a different object, * (3) reallocated to a different offset, or * (4) cleaned. */ if (!vm_page_in_laundry(m) || m->object != object || m->pindex != pindex || m->dirty == 0) { error = ENXIO; goto unlock_all; } /* * The page may have been busied while the object lock was * released. */ if (vm_page_tryxbusy(m) == 0) { error = EBUSY; goto unlock_all; } } /* * Remove all writeable mappings, failing if the page is wired. */ if (!vm_page_try_remove_write(m)) { vm_page_xunbusy(m); error = EBUSY; goto unlock_all; } /* * If a page is dirty, then it is either being washed * (but not yet cleaned) or it is still in the * laundry. If it is still in the laundry, then we * start the cleaning operation. */ if ((*numpagedout = vm_pageout_cluster(m)) == 0) error = EIO; unlock_all: VM_OBJECT_WUNLOCK(object); unlock_mp: if (mp != NULL) { if (vp != NULL) vput(vp); vm_object_deallocate(object); vn_finished_write(mp); } return (error); } /* * Attempt to launder the specified number of pages. * * Returns the number of pages successfully laundered. */ static int vm_pageout_launder(struct vm_domain *vmd, int launder, bool in_shortfall) { struct scan_state ss; struct vm_pagequeue *pq; vm_object_t object; vm_page_t m, marker; vm_page_astate_t new, old; int act_delta, error, numpagedout, queue, refs, starting_target; int vnodes_skipped; bool pageout_ok; object = NULL; starting_target = launder; vnodes_skipped = 0; /* * Scan the laundry queues for pages eligible to be laundered. We stop * once the target number of dirty pages have been laundered, or once * we've reached the end of the queue. A single iteration of this loop * may cause more than one page to be laundered because of clustering. * * As an optimization, we avoid laundering from PQ_UNSWAPPABLE when no * swap devices are configured. */ if (atomic_load_acq_int(&swapdev_enabled)) queue = PQ_UNSWAPPABLE; else queue = PQ_LAUNDRY; scan: marker = &vmd->vmd_markers[queue]; pq = &vmd->vmd_pagequeues[queue]; vm_pagequeue_lock(pq); vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt); while (launder > 0 && (m = vm_pageout_next(&ss, false)) != NULL) { if (__predict_false((m->flags & PG_MARKER) != 0)) continue; /* * Don't touch a page that was removed from the queue after the * page queue lock was released. Otherwise, ensure that any * pending queue operations, such as dequeues for wired pages, * are handled. */ if (vm_pageout_defer(m, queue, true)) continue; /* * Lock the page's object. */ if (object == NULL || object != m->object) { if (object != NULL) VM_OBJECT_WUNLOCK(object); object = atomic_load_ptr(&m->object); if (__predict_false(object == NULL)) /* The page is being freed by another thread. */ continue; /* Depends on type-stability. */ VM_OBJECT_WLOCK(object); if (__predict_false(m->object != object)) { VM_OBJECT_WUNLOCK(object); object = NULL; continue; } } if (vm_page_tryxbusy(m) == 0) continue; /* * Check for wirings now that we hold the object lock and have * exclusively busied the page. If the page is mapped, it may * still be wired by pmap lookups. The call to * vm_page_try_remove_all() below atomically checks for such * wirings and removes mappings. If the page is unmapped, the * wire count is guaranteed not to increase after this check. */ if (__predict_false(vm_page_wired(m))) goto skip_page; /* * Invalid pages can be easily freed. They cannot be * mapped; vm_page_free() asserts this. */ if (vm_page_none_valid(m)) goto free_page; refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0; for (old = vm_page_astate_load(m);;) { /* * Check to see if the page has been removed from the * queue since the first such check. Leave it alone if * so, discarding any references collected by * pmap_ts_referenced(). */ if (__predict_false(_vm_page_queue(old) == PQ_NONE)) goto skip_page; new = old; act_delta = refs; if ((old.flags & PGA_REFERENCED) != 0) { new.flags &= ~PGA_REFERENCED; act_delta++; } if (act_delta == 0) { ; } else if (object->ref_count != 0) { /* * Increase the activation count if the page was * referenced while in the laundry queue. This * makes it less likely that the page will be * returned prematurely to the laundry queue. */ new.act_count += ACT_ADVANCE + act_delta; if (new.act_count > ACT_MAX) new.act_count = ACT_MAX; new.flags &= ~PGA_QUEUE_OP_MASK; new.flags |= PGA_REQUEUE; new.queue = PQ_ACTIVE; if (!vm_page_pqstate_commit(m, &old, new)) continue; /* * If this was a background laundering, count * activated pages towards our target. The * purpose of background laundering is to ensure * that pages are eventually cycled through the * laundry queue, and an activation is a valid * way out. */ if (!in_shortfall) launder--; VM_CNT_INC(v_reactivated); goto skip_page; } else if ((object->flags & OBJ_DEAD) == 0) { new.flags |= PGA_REQUEUE; if (!vm_page_pqstate_commit(m, &old, new)) continue; goto skip_page; } break; } /* * If the page appears to be clean at the machine-independent * layer, then remove all of its mappings from the pmap in * anticipation of freeing it. If, however, any of the page's * mappings allow write access, then the page may still be * modified until the last of those mappings are removed. */ if (object->ref_count != 0) { vm_page_test_dirty(m); if (m->dirty == 0 && !vm_page_try_remove_all(m)) goto skip_page; } /* * Clean pages are freed, and dirty pages are paged out unless * they belong to a dead object. Requeueing dirty pages from * dead objects is pointless, as they are being paged out and * freed by the thread that destroyed the object. */ if (m->dirty == 0) { free_page: /* * Now we are guaranteed that no other threads are * manipulating the page, check for a last-second * reference. */ if (vm_pageout_defer(m, queue, true)) goto skip_page; vm_page_free(m); VM_CNT_INC(v_dfree); } else if ((object->flags & OBJ_DEAD) == 0) { if ((object->flags & OBJ_SWAP) != 0) pageout_ok = disable_swap_pageouts == 0; else pageout_ok = true; if (!pageout_ok) { vm_page_launder(m); goto skip_page; } /* * Form a cluster with adjacent, dirty pages from the * same object, and page out that entire cluster. * * The adjacent, dirty pages must also be in the * laundry. However, their mappings are not checked * for new references. Consequently, a recently * referenced page may be paged out. However, that * page will not be prematurely reclaimed. After page * out, the page will be placed in the inactive queue, * where any new references will be detected and the * page reactivated. */ error = vm_pageout_clean(m, &numpagedout); if (error == 0) { launder -= numpagedout; ss.scanned += numpagedout; } else if (error == EDEADLK) { pageout_lock_miss++; vnodes_skipped++; } object = NULL; } else { skip_page: vm_page_xunbusy(m); } } if (object != NULL) { VM_OBJECT_WUNLOCK(object); object = NULL; } vm_pagequeue_lock(pq); vm_pageout_end_scan(&ss); vm_pagequeue_unlock(pq); if (launder > 0 && queue == PQ_UNSWAPPABLE) { queue = PQ_LAUNDRY; goto scan; } /* * Wakeup the sync daemon if we skipped a vnode in a writeable object * and we didn't launder enough pages. */ if (vnodes_skipped > 0 && launder > 0) (void)speedup_syncer(); return (starting_target - launder); } /* * Compute the integer square root. */ static u_int isqrt(u_int num) { u_int bit, root, tmp; bit = num != 0 ? (1u << ((fls(num) - 1) & ~1)) : 0; root = 0; while (bit != 0) { tmp = root + bit; root >>= 1; if (num >= tmp) { num -= tmp; root += bit; } bit >>= 2; } return (root); } /* * Perform the work of the laundry thread: periodically wake up and determine * whether any pages need to be laundered. If so, determine the number of pages * that need to be laundered, and launder them. */ static void vm_pageout_laundry_worker(void *arg) { struct vm_domain *vmd; struct vm_pagequeue *pq; uint64_t nclean, ndirty, nfreed; int domain, last_target, launder, shortfall, shortfall_cycle, target; bool in_shortfall; domain = (uintptr_t)arg; vmd = VM_DOMAIN(domain); pq = &vmd->vmd_pagequeues[PQ_LAUNDRY]; KASSERT(vmd->vmd_segs != 0, ("domain without segments")); shortfall = 0; in_shortfall = false; shortfall_cycle = 0; last_target = target = 0; nfreed = 0; /* * Calls to these handlers are serialized by the swap syscall lock. */ (void)EVENTHANDLER_REGISTER(swapon, vm_pageout_swapon, vmd, EVENTHANDLER_PRI_ANY); (void)EVENTHANDLER_REGISTER(swapoff, vm_pageout_swapoff, vmd, EVENTHANDLER_PRI_ANY); /* * The pageout laundry worker is never done, so loop forever. */ for (;;) { KASSERT(target >= 0, ("negative target %d", target)); KASSERT(shortfall_cycle >= 0, ("negative cycle %d", shortfall_cycle)); launder = 0; /* * First determine whether we need to launder pages to meet a * shortage of free pages. */ if (shortfall > 0) { in_shortfall = true; shortfall_cycle = VM_LAUNDER_RATE / VM_INACT_SCAN_RATE; target = shortfall; } else if (!in_shortfall) goto trybackground; else if (shortfall_cycle == 0 || vm_laundry_target(vmd) <= 0) { /* * We recently entered shortfall and began laundering * pages. If we have completed that laundering run * (and we are no longer in shortfall) or we have met * our laundry target through other activity, then we * can stop laundering pages. */ in_shortfall = false; target = 0; goto trybackground; } launder = target / shortfall_cycle--; goto dolaundry; /* * There's no immediate need to launder any pages; see if we * meet the conditions to perform background laundering: * * 1. The ratio of dirty to clean inactive pages exceeds the * background laundering threshold, or * 2. we haven't yet reached the target of the current * background laundering run. * * The background laundering threshold is not a constant. * Instead, it is a slowly growing function of the number of * clean pages freed by the page daemon since the last * background laundering. Thus, as the ratio of dirty to * clean inactive pages grows, the amount of memory pressure * required to trigger laundering decreases. We ensure * that the threshold is non-zero after an inactive queue * scan, even if that scan failed to free a single clean page. */ trybackground: nclean = vmd->vmd_free_count + vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt; ndirty = vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt; if (target == 0 && ndirty * isqrt(howmany(nfreed + 1, vmd->vmd_free_target - vmd->vmd_free_min)) >= nclean) { target = vmd->vmd_background_launder_target; } /* * We have a non-zero background laundering target. If we've * laundered up to our maximum without observing a page daemon * request, just stop. This is a safety belt that ensures we * don't launder an excessive amount if memory pressure is low * and the ratio of dirty to clean pages is large. Otherwise, * proceed at the background laundering rate. */ if (target > 0) { if (nfreed > 0) { nfreed = 0; last_target = target; } else if (last_target - target >= vm_background_launder_max * PAGE_SIZE / 1024) { target = 0; } launder = vm_background_launder_rate * PAGE_SIZE / 1024; launder /= VM_LAUNDER_RATE; if (launder > target) launder = target; } dolaundry: if (launder > 0) { /* * Because of I/O clustering, the number of laundered * pages could exceed "target" by the maximum size of * a cluster minus one. */ target -= min(vm_pageout_launder(vmd, launder, in_shortfall), target); pause("laundp", hz / VM_LAUNDER_RATE); } /* * If we're not currently laundering pages and the page daemon * hasn't posted a new request, sleep until the page daemon * kicks us. */ vm_pagequeue_lock(pq); if (target == 0 && vmd->vmd_laundry_request == VM_LAUNDRY_IDLE) (void)mtx_sleep(&vmd->vmd_laundry_request, vm_pagequeue_lockptr(pq), PVM, "launds", 0); /* * If the pagedaemon has indicated that it's in shortfall, start * a shortfall laundering unless we're already in the middle of * one. This may preempt a background laundering. */ if (vmd->vmd_laundry_request == VM_LAUNDRY_SHORTFALL && (!in_shortfall || shortfall_cycle == 0)) { shortfall = vm_laundry_target(vmd) + vmd->vmd_pageout_deficit; target = 0; } else shortfall = 0; if (target == 0) vmd->vmd_laundry_request = VM_LAUNDRY_IDLE; nfreed += vmd->vmd_clean_pages_freed; vmd->vmd_clean_pages_freed = 0; vm_pagequeue_unlock(pq); } } /* * Compute the number of pages we want to try to move from the * active queue to either the inactive or laundry queue. * * When scanning active pages during a shortage, we make clean pages * count more heavily towards the page shortage than dirty pages. * This is because dirty pages must be laundered before they can be * reused and thus have less utility when attempting to quickly * alleviate a free page shortage. However, this weighting also * causes the scan to deactivate dirty pages more aggressively, * improving the effectiveness of clustering. */ static int vm_pageout_active_target(struct vm_domain *vmd) { int shortage; shortage = vmd->vmd_inactive_target + vm_paging_target(vmd) - (vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt + vmd->vmd_pagequeues[PQ_LAUNDRY].pq_cnt / act_scan_laundry_weight); shortage *= act_scan_laundry_weight; return (shortage); } /* * Scan the active queue. If there is no shortage of inactive pages, scan a * small portion of the queue in order to maintain quasi-LRU. */ static void vm_pageout_scan_active(struct vm_domain *vmd, int page_shortage) { struct scan_state ss; vm_object_t object; vm_page_t m, marker; struct vm_pagequeue *pq; vm_page_astate_t old, new; long min_scan; int act_delta, max_scan, ps_delta, refs, scan_tick; uint8_t nqueue; marker = &vmd->vmd_markers[PQ_ACTIVE]; pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; vm_pagequeue_lock(pq); /* * If we're just idle polling attempt to visit every * active page within 'update_period' seconds. */ scan_tick = ticks; if (vm_pageout_update_period != 0) { min_scan = pq->pq_cnt; min_scan *= scan_tick - vmd->vmd_last_active_scan; min_scan /= hz * vm_pageout_update_period; } else min_scan = 0; if (min_scan > 0 || (page_shortage > 0 && pq->pq_cnt > 0)) vmd->vmd_last_active_scan = scan_tick; /* * Scan the active queue for pages that can be deactivated. Update * the per-page activity counter and use it to identify deactivation * candidates. Held pages may be deactivated. * * To avoid requeuing each page that remains in the active queue, we * implement the CLOCK algorithm. To keep the implementation of the * enqueue operation consistent for all page queues, we use two hands, * represented by marker pages. Scans begin at the first hand, which * precedes the second hand in the queue. When the two hands meet, * they are moved back to the head and tail of the queue, respectively, * and scanning resumes. */ max_scan = page_shortage > 0 ? pq->pq_cnt : min_scan; act_scan: vm_pageout_init_scan(&ss, pq, marker, &vmd->vmd_clock[0], max_scan); while ((m = vm_pageout_next(&ss, false)) != NULL) { if (__predict_false(m == &vmd->vmd_clock[1])) { vm_pagequeue_lock(pq); TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q); TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[1], plinks.q); TAILQ_INSERT_HEAD(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q); TAILQ_INSERT_TAIL(&pq->pq_pl, &vmd->vmd_clock[1], plinks.q); max_scan -= ss.scanned; vm_pageout_end_scan(&ss); goto act_scan; } if (__predict_false((m->flags & PG_MARKER) != 0)) continue; /* * Don't touch a page that was removed from the queue after the * page queue lock was released. Otherwise, ensure that any * pending queue operations, such as dequeues for wired pages, * are handled. */ if (vm_pageout_defer(m, PQ_ACTIVE, true)) continue; /* * A page's object pointer may be set to NULL before * the object lock is acquired. */ object = atomic_load_ptr(&m->object); if (__predict_false(object == NULL)) /* * The page has been removed from its object. */ continue; /* Deferred free of swap space. */ if ((m->a.flags & PGA_SWAP_FREE) != 0 && VM_OBJECT_TRYWLOCK(object)) { if (m->object == object) vm_pager_page_unswapped(m); VM_OBJECT_WUNLOCK(object); } /* * Check to see "how much" the page has been used. * * Test PGA_REFERENCED after calling pmap_ts_referenced() so * that a reference from a concurrently destroyed mapping is * observed here and now. * * Perform an unsynchronized object ref count check. While * the page lock ensures that the page is not reallocated to * another object, in particular, one with unmanaged mappings * that cannot support pmap_ts_referenced(), two races are, * nonetheless, possible: * 1) The count was transitioning to zero, but we saw a non- * zero value. pmap_ts_referenced() will return zero * because the page is not mapped. * 2) The count was transitioning to one, but we saw zero. * This race delays the detection of a new reference. At * worst, we will deactivate and reactivate the page. */ refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0; old = vm_page_astate_load(m); do { /* * Check to see if the page has been removed from the * queue since the first such check. Leave it alone if * so, discarding any references collected by * pmap_ts_referenced(). */ if (__predict_false(_vm_page_queue(old) == PQ_NONE)) { ps_delta = 0; break; } /* * Advance or decay the act_count based on recent usage. */ new = old; act_delta = refs; if ((old.flags & PGA_REFERENCED) != 0) { new.flags &= ~PGA_REFERENCED; act_delta++; } if (act_delta != 0) { new.act_count += ACT_ADVANCE + act_delta; if (new.act_count > ACT_MAX) new.act_count = ACT_MAX; } else { new.act_count -= min(new.act_count, ACT_DECLINE); } if (new.act_count > 0) { /* * Adjust the activation count and keep the page * in the active queue. The count might be left * unchanged if it is saturated. The page may * have been moved to a different queue since we * started the scan, in which case we move it * back. */ ps_delta = 0; if (old.queue != PQ_ACTIVE) { new.flags &= ~PGA_QUEUE_OP_MASK; new.flags |= PGA_REQUEUE; new.queue = PQ_ACTIVE; } } else { /* * When not short for inactive pages, let dirty * pages go through the inactive queue before * moving to the laundry queue. This gives them * some extra time to be reactivated, * potentially avoiding an expensive pageout. * However, during a page shortage, the inactive * queue is necessarily small, and so dirty * pages would only spend a trivial amount of * time in the inactive queue. Therefore, we * might as well place them directly in the * laundry queue to reduce queuing overhead. * * Calling vm_page_test_dirty() here would * require acquisition of the object's write * lock. However, during a page shortage, * directing dirty pages into the laundry queue * is only an optimization and not a * requirement. Therefore, we simply rely on * the opportunistic updates to the page's dirty * field by the pmap. */ if (page_shortage <= 0) { nqueue = PQ_INACTIVE; ps_delta = 0; } else if (m->dirty == 0) { nqueue = PQ_INACTIVE; ps_delta = act_scan_laundry_weight; } else { nqueue = PQ_LAUNDRY; ps_delta = 1; } new.flags &= ~PGA_QUEUE_OP_MASK; new.flags |= PGA_REQUEUE; new.queue = nqueue; } } while (!vm_page_pqstate_commit(m, &old, new)); page_shortage -= ps_delta; } vm_pagequeue_lock(pq); TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_clock[0], plinks.q); TAILQ_INSERT_AFTER(&pq->pq_pl, marker, &vmd->vmd_clock[0], plinks.q); vm_pageout_end_scan(&ss); vm_pagequeue_unlock(pq); } static int vm_pageout_reinsert_inactive_page(struct vm_pagequeue *pq, vm_page_t marker, vm_page_t m) { vm_page_astate_t as; vm_pagequeue_assert_locked(pq); as = vm_page_astate_load(m); if (as.queue != PQ_INACTIVE || (as.flags & PGA_ENQUEUED) != 0) return (0); vm_page_aflag_set(m, PGA_ENQUEUED); TAILQ_INSERT_BEFORE(marker, m, plinks.q); return (1); } /* * Re-add stuck pages to the inactive queue. We will examine them again * during the next scan. If the queue state of a page has changed since * it was physically removed from the page queue in * vm_pageout_collect_batch(), don't do anything with that page. */ static void vm_pageout_reinsert_inactive(struct scan_state *ss, struct vm_batchqueue *bq, vm_page_t m) { struct vm_pagequeue *pq; vm_page_t marker; int delta; delta = 0; marker = ss->marker; pq = ss->pq; if (m != NULL) { if (vm_batchqueue_insert(bq, m) != 0) return; vm_pagequeue_lock(pq); delta += vm_pageout_reinsert_inactive_page(pq, marker, m); } else vm_pagequeue_lock(pq); while ((m = vm_batchqueue_pop(bq)) != NULL) delta += vm_pageout_reinsert_inactive_page(pq, marker, m); vm_pagequeue_cnt_add(pq, delta); vm_pagequeue_unlock(pq); vm_batchqueue_init(bq); } static void vm_pageout_scan_inactive(struct vm_domain *vmd, int page_shortage) { struct timeval start, end; struct scan_state ss; struct vm_batchqueue rq; struct vm_page marker_page; vm_page_t m, marker; struct vm_pagequeue *pq; vm_object_t object; vm_page_astate_t old, new; - int act_delta, addl_page_shortage, starting_page_shortage, refs; + int act_delta, addl_page_shortage, dirty_count, dirty_thresh; + int starting_page_shortage, refs; object = NULL; vm_batchqueue_init(&rq); getmicrouptime(&start); /* * The addl_page_shortage is an estimate of the number of temporarily * stuck pages in the inactive queue. In other words, the * number of pages from the inactive count that should be * discounted in setting the target for the active queue scan. */ addl_page_shortage = 0; + /* + * dirty_count is the number of pages encountered that require + * laundering before reclamation is possible. If we encounter a large + * number of dirty pages, we may abort the scan without meeting the page + * shortage in the hope that laundering will allow a future scan to meet + * the target. + */ + dirty_count = 0; + dirty_thresh = inact_scan_laundry_weight * page_shortage; + if (dirty_thresh == 0) + dirty_thresh = INT_MAX; + /* * Start scanning the inactive queue for pages that we can free. The * scan will stop when we reach the target or we have scanned the * entire queue. (Note that m->a.act_count is not used to make * decisions for the inactive queue, only for the active queue.) */ starting_page_shortage = page_shortage; marker = &marker_page; vm_page_init_marker(marker, PQ_INACTIVE, 0); pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; vm_pagequeue_lock(pq); vm_pageout_init_scan(&ss, pq, marker, NULL, pq->pq_cnt); - while (page_shortage > 0) { + while (page_shortage > 0 && dirty_count < dirty_thresh) { /* * If we need to refill the scan batch queue, release any * optimistically held object lock. This gives someone else a * chance to grab the lock, and also avoids holding it while we * do unrelated work. */ if (object != NULL && vm_batchqueue_empty(&ss.bq)) { VM_OBJECT_WUNLOCK(object); object = NULL; } m = vm_pageout_next(&ss, true); if (m == NULL) break; KASSERT((m->flags & PG_MARKER) == 0, ("marker page %p was dequeued", m)); /* * Don't touch a page that was removed from the queue after the * page queue lock was released. Otherwise, ensure that any * pending queue operations, such as dequeues for wired pages, * are handled. */ if (vm_pageout_defer(m, PQ_INACTIVE, false)) continue; /* * Lock the page's object. */ if (object == NULL || object != m->object) { if (object != NULL) VM_OBJECT_WUNLOCK(object); object = atomic_load_ptr(&m->object); if (__predict_false(object == NULL)) /* The page is being freed by another thread. */ continue; /* Depends on type-stability. */ VM_OBJECT_WLOCK(object); if (__predict_false(m->object != object)) { VM_OBJECT_WUNLOCK(object); object = NULL; goto reinsert; } } if (vm_page_tryxbusy(m) == 0) { /* * Don't mess with busy pages. Leave them at * the front of the queue. Most likely, they * are being paged out and will leave the * queue shortly after the scan finishes. So, * they ought to be discounted from the * inactive count. */ addl_page_shortage++; goto reinsert; } /* Deferred free of swap space. */ if ((m->a.flags & PGA_SWAP_FREE) != 0) vm_pager_page_unswapped(m); /* * Check for wirings now that we hold the object lock and have * exclusively busied the page. If the page is mapped, it may * still be wired by pmap lookups. The call to * vm_page_try_remove_all() below atomically checks for such * wirings and removes mappings. If the page is unmapped, the * wire count is guaranteed not to increase after this check. */ if (__predict_false(vm_page_wired(m))) goto skip_page; /* * Invalid pages can be easily freed. They cannot be * mapped, vm_page_free() asserts this. */ if (vm_page_none_valid(m)) goto free_page; refs = object->ref_count != 0 ? pmap_ts_referenced(m) : 0; for (old = vm_page_astate_load(m);;) { /* * Check to see if the page has been removed from the * queue since the first such check. Leave it alone if * so, discarding any references collected by * pmap_ts_referenced(). */ if (__predict_false(_vm_page_queue(old) == PQ_NONE)) goto skip_page; new = old; act_delta = refs; if ((old.flags & PGA_REFERENCED) != 0) { new.flags &= ~PGA_REFERENCED; act_delta++; } if (act_delta == 0) { ; } else if (object->ref_count != 0) { /* * Increase the activation count if the * page was referenced while in the * inactive queue. This makes it less * likely that the page will be returned * prematurely to the inactive queue. */ new.act_count += ACT_ADVANCE + act_delta; if (new.act_count > ACT_MAX) new.act_count = ACT_MAX; new.flags &= ~PGA_QUEUE_OP_MASK; new.flags |= PGA_REQUEUE; new.queue = PQ_ACTIVE; if (!vm_page_pqstate_commit(m, &old, new)) continue; VM_CNT_INC(v_reactivated); goto skip_page; } else if ((object->flags & OBJ_DEAD) == 0) { new.queue = PQ_INACTIVE; new.flags |= PGA_REQUEUE; if (!vm_page_pqstate_commit(m, &old, new)) continue; goto skip_page; } break; } /* * If the page appears to be clean at the machine-independent * layer, then remove all of its mappings from the pmap in * anticipation of freeing it. If, however, any of the page's * mappings allow write access, then the page may still be * modified until the last of those mappings are removed. */ if (object->ref_count != 0) { vm_page_test_dirty(m); if (m->dirty == 0 && !vm_page_try_remove_all(m)) goto skip_page; } /* * Clean pages can be freed, but dirty pages must be sent back * to the laundry, unless they belong to a dead object. * Requeueing dirty pages from dead objects is pointless, as * they are being paged out and freed by the thread that * destroyed the object. */ if (m->dirty == 0) { free_page: /* * Now we are guaranteed that no other threads are * manipulating the page, check for a last-second * reference that would save it from doom. */ if (vm_pageout_defer(m, PQ_INACTIVE, false)) goto skip_page; /* * Because we dequeued the page and have already checked * for pending dequeue and enqueue requests, we can * safely disassociate the page from the inactive queue * without holding the queue lock. */ m->a.queue = PQ_NONE; vm_page_free(m); page_shortage--; continue; } - if ((object->flags & OBJ_DEAD) == 0) + if ((object->flags & OBJ_DEAD) == 0) { vm_page_launder(m); + + /* + * If the page would be paged out to a swap device, and + * no devices are configured or they are all nearly + * full, then don't count it against our threshold, + * since it most likely can't be used to meet our + * target. + */ + if ((object->flags & OBJ_SWAP) == 0 || + !atomic_load_bool(&swap_pager_almost_full)) + dirty_count++; + } skip_page: vm_page_xunbusy(m); continue; reinsert: vm_pageout_reinsert_inactive(&ss, &rq, m); } if (object != NULL) VM_OBJECT_WUNLOCK(object); vm_pageout_reinsert_inactive(&ss, &rq, NULL); vm_pageout_reinsert_inactive(&ss, &ss.bq, NULL); vm_pagequeue_lock(pq); vm_pageout_end_scan(&ss); vm_pagequeue_unlock(pq); /* * Record the remaining shortage and the progress and rate it was made. */ atomic_add_int(&vmd->vmd_addl_shortage, addl_page_shortage); getmicrouptime(&end); timevalsub(&end, &start); atomic_add_int(&vmd->vmd_inactive_us, end.tv_sec * 1000000 + end.tv_usec); atomic_add_int(&vmd->vmd_inactive_freed, starting_page_shortage - page_shortage); } /* * Dispatch a number of inactive threads according to load and collect the * results to present a coherent view of paging activity on this domain. */ static int vm_pageout_inactive_dispatch(struct vm_domain *vmd, int shortage) { u_int freed, pps, slop, threads, us; vmd->vmd_inactive_shortage = shortage; slop = 0; /* * If we have more work than we can do in a quarter of our interval, we * fire off multiple threads to process it. */ if ((threads = vmd->vmd_inactive_threads) > 1 && vmd->vmd_helper_threads_enabled && vmd->vmd_inactive_pps != 0 && shortage > vmd->vmd_inactive_pps / VM_INACT_SCAN_RATE / 4) { vmd->vmd_inactive_shortage /= threads; slop = shortage % threads; vm_domain_pageout_lock(vmd); blockcount_acquire(&vmd->vmd_inactive_starting, threads - 1); blockcount_acquire(&vmd->vmd_inactive_running, threads - 1); wakeup(&vmd->vmd_inactive_shortage); vm_domain_pageout_unlock(vmd); } /* Run the local thread scan. */ vm_pageout_scan_inactive(vmd, vmd->vmd_inactive_shortage + slop); /* * Block until helper threads report results and then accumulate * totals. */ blockcount_wait(&vmd->vmd_inactive_running, NULL, "vmpoid", PVM); freed = atomic_readandclear_int(&vmd->vmd_inactive_freed); VM_CNT_ADD(v_dfree, freed); /* * Calculate the per-thread paging rate with an exponential decay of * prior results. Careful to avoid integer rounding errors with large * us values. */ us = max(atomic_readandclear_int(&vmd->vmd_inactive_us), 1); if (us > 1000000) /* Keep rounding to tenths */ pps = (freed * 10) / ((us * 10) / 1000000); else pps = (1000000 / us) * freed; vmd->vmd_inactive_pps = (vmd->vmd_inactive_pps / 2) + (pps / 2); return (shortage - freed); } /* * Attempt to reclaim the requested number of pages from the inactive queue. * Returns true if the shortage was addressed. */ static int vm_pageout_inactive(struct vm_domain *vmd, int shortage, int *addl_shortage) { struct vm_pagequeue *pq; u_int addl_page_shortage, deficit, page_shortage; u_int starting_page_shortage; /* * vmd_pageout_deficit counts the number of pages requested in * allocations that failed because of a free page shortage. We assume * that the allocations will be reattempted and thus include the deficit * in our scan target. */ deficit = atomic_readandclear_int(&vmd->vmd_pageout_deficit); starting_page_shortage = shortage + deficit; /* * Run the inactive scan on as many threads as is necessary. */ page_shortage = vm_pageout_inactive_dispatch(vmd, starting_page_shortage); addl_page_shortage = atomic_readandclear_int(&vmd->vmd_addl_shortage); /* * Wake up the laundry thread so that it can perform any needed * laundering. If we didn't meet our target, we're in shortfall and * need to launder more aggressively. If PQ_LAUNDRY is empty and no * swap devices are configured, the laundry thread has no work to do, so * don't bother waking it up. * * The laundry thread uses the number of inactive queue scans elapsed * since the last laundering to determine whether to launder again, so * keep count. */ if (starting_page_shortage > 0) { pq = &vmd->vmd_pagequeues[PQ_LAUNDRY]; vm_pagequeue_lock(pq); if (vmd->vmd_laundry_request == VM_LAUNDRY_IDLE && (pq->pq_cnt > 0 || atomic_load_acq_int(&swapdev_enabled))) { if (page_shortage > 0) { vmd->vmd_laundry_request = VM_LAUNDRY_SHORTFALL; VM_CNT_INC(v_pdshortfalls); } else if (vmd->vmd_laundry_request != VM_LAUNDRY_SHORTFALL) vmd->vmd_laundry_request = VM_LAUNDRY_BACKGROUND; wakeup(&vmd->vmd_laundry_request); } vmd->vmd_clean_pages_freed += starting_page_shortage - page_shortage; vm_pagequeue_unlock(pq); } /* * If the inactive queue scan fails repeatedly to meet its * target, kill the largest process. */ vm_pageout_mightbe_oom(vmd, page_shortage, starting_page_shortage); /* * See the description of addl_page_shortage above. */ *addl_shortage = addl_page_shortage + deficit; return (page_shortage <= 0); } static int vm_pageout_oom_vote; /* * The pagedaemon threads randlomly select one to perform the * OOM. Trying to kill processes before all pagedaemons * failed to reach free target is premature. */ static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int page_shortage, int starting_page_shortage) { int old_vote; /* * Do not trigger an OOM kill if the page daemon is able to make * progress, or if there is no instantaneous shortage. The latter case * can happen if the PID controller is still reacting to an acute * shortage, and the inactive queue is full of dirty pages. */ if (starting_page_shortage <= 0 || starting_page_shortage != page_shortage || !vm_paging_needed(vmd, vmd->vmd_free_count)) vmd->vmd_oom_seq = 0; else vmd->vmd_oom_seq++; if (vmd->vmd_oom_seq < vm_pageout_oom_seq) { if (vmd->vmd_oom) { vmd->vmd_oom = false; atomic_subtract_int(&vm_pageout_oom_vote, 1); } return; } /* * Do not follow the call sequence until OOM condition is * cleared. */ vmd->vmd_oom_seq = 0; if (vmd->vmd_oom) return; vmd->vmd_oom = true; old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); if (old_vote != vm_ndomains - 1) return; /* * The current pagedaemon thread is the last in the quorum to * start OOM. Initiate the selection and signaling of the * victim. */ vm_pageout_oom(VM_OOM_MEM); /* * After one round of OOM terror, recall our vote. On the * next pass, current pagedaemon would vote again if the low * memory condition is still there, due to vmd_oom being * false. */ vmd->vmd_oom = false; atomic_subtract_int(&vm_pageout_oom_vote, 1); } /* * The OOM killer is the page daemon's action of last resort when * memory allocation requests have been stalled for a prolonged period * of time because it cannot reclaim memory. This function computes * the approximate number of physical pages that could be reclaimed if * the specified address space is destroyed. * * Private, anonymous memory owned by the address space is the * principal resource that we expect to recover after an OOM kill. * Since the physical pages mapped by the address space's COW entries * are typically shared pages, they are unlikely to be released and so * they are not counted. * * To get to the point where the page daemon runs the OOM killer, its * efforts to write-back vnode-backed pages may have stalled. This * could be caused by a memory allocation deadlock in the write path * that might be resolved by an OOM kill. Therefore, physical pages * belonging to vnode-backed objects are counted, because they might * be freed without being written out first if the address space holds * the last reference to an unlinked vnode. * * Similarly, physical pages belonging to OBJT_PHYS objects are * counted because the address space might hold the last reference to * the object. */ static long vm_pageout_oom_pagecount(struct vmspace *vmspace) { vm_map_t map; vm_map_entry_t entry; vm_object_t obj; long res; map = &vmspace->vm_map; KASSERT(!vm_map_is_system(map), ("system map")); sx_assert(&map->lock, SA_LOCKED); res = 0; VM_MAP_ENTRY_FOREACH(entry, map) { if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) continue; obj = entry->object.vm_object; if (obj == NULL) continue; if ((entry->eflags & MAP_ENTRY_NEEDS_COPY) != 0 && obj->ref_count != 1) continue; if (obj->type == OBJT_PHYS || obj->type == OBJT_VNODE || (obj->flags & OBJ_SWAP) != 0) res += obj->resident_page_count; } return (res); } static int vm_oom_ratelim_last; static int vm_oom_pf_secs = 10; SYSCTL_INT(_vm, OID_AUTO, oom_pf_secs, CTLFLAG_RWTUN, &vm_oom_pf_secs, 0, ""); static struct mtx vm_oom_ratelim_mtx; void vm_pageout_oom(int shortage) { const char *reason; struct proc *p, *bigproc; vm_offset_t size, bigsize; struct thread *td; struct vmspace *vm; int now; bool breakout; /* * For OOM requests originating from vm_fault(), there is a high * chance that a single large process faults simultaneously in * several threads. Also, on an active system running many * processes of middle-size, like buildworld, all of them * could fault almost simultaneously as well. * * To avoid killing too many processes, rate-limit OOMs * initiated by vm_fault() time-outs on the waits for free * pages. */ mtx_lock(&vm_oom_ratelim_mtx); now = ticks; if (shortage == VM_OOM_MEM_PF && (u_int)(now - vm_oom_ratelim_last) < hz * vm_oom_pf_secs) { mtx_unlock(&vm_oom_ratelim_mtx); return; } vm_oom_ratelim_last = now; mtx_unlock(&vm_oom_ratelim_mtx); /* * We keep the process bigproc locked once we find it to keep anyone * from messing with it; however, there is a possibility of * deadlock if process B is bigproc and one of its child processes * attempts to propagate a signal to B while we are waiting for A's * lock while walking this list. To avoid this, we don't block on * the process lock but just skip a process if it is already locked. */ bigproc = NULL; bigsize = 0; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { PROC_LOCK(p); /* * If this is a system, protected or killed process, skip it. */ if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 || p->p_pid == 1 || P_KILLED(p) || (p->p_pid < 48 && swap_pager_avail != 0)) { PROC_UNLOCK(p); continue; } /* * If the process is in a non-running type state, * don't touch it. Check all the threads individually. */ breakout = false; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!TD_ON_RUNQ(td) && !TD_IS_RUNNING(td) && !TD_IS_SLEEPING(td) && !TD_IS_SUSPENDED(td)) { thread_unlock(td); breakout = true; break; } thread_unlock(td); } if (breakout) { PROC_UNLOCK(p); continue; } /* * get the process size */ vm = vmspace_acquire_ref(p); if (vm == NULL) { PROC_UNLOCK(p); continue; } _PHOLD(p); PROC_UNLOCK(p); sx_sunlock(&allproc_lock); if (!vm_map_trylock_read(&vm->vm_map)) { vmspace_free(vm); sx_slock(&allproc_lock); PRELE(p); continue; } size = vmspace_swap_count(vm); if (shortage == VM_OOM_MEM || shortage == VM_OOM_MEM_PF) size += vm_pageout_oom_pagecount(vm); vm_map_unlock_read(&vm->vm_map); vmspace_free(vm); sx_slock(&allproc_lock); /* * If this process is bigger than the biggest one, * remember it. */ if (size > bigsize) { if (bigproc != NULL) PRELE(bigproc); bigproc = p; bigsize = size; } else { PRELE(p); } } sx_sunlock(&allproc_lock); if (bigproc != NULL) { switch (shortage) { case VM_OOM_MEM: reason = "failed to reclaim memory"; break; case VM_OOM_MEM_PF: reason = "a thread waited too long to allocate a page"; break; case VM_OOM_SWAPZ: reason = "out of swap space"; break; default: panic("unknown OOM reason %d", shortage); } if (vm_panic_on_oom != 0 && --vm_panic_on_oom == 0) panic("%s", reason); PROC_LOCK(bigproc); killproc(bigproc, reason); sched_nice(bigproc, PRIO_MIN); _PRELE(bigproc); PROC_UNLOCK(bigproc); } } /* * Signal a free page shortage to subsystems that have registered an event * handler. Reclaim memory from UMA in the event of a severe shortage. * Return true if the free page count should be re-evaluated. */ static bool vm_pageout_lowmem(void) { static int lowmem_ticks = 0; int last; bool ret; ret = false; last = atomic_load_int(&lowmem_ticks); while ((u_int)(ticks - last) / hz >= lowmem_period) { if (atomic_fcmpset_int(&lowmem_ticks, &last, ticks) == 0) continue; /* * Decrease registered cache sizes. */ SDT_PROBE0(vm, , , vm__lowmem_scan); EVENTHANDLER_INVOKE(vm_lowmem, VM_LOW_PAGES); /* * We do this explicitly after the caches have been * drained above. */ uma_reclaim(UMA_RECLAIM_TRIM); ret = true; break; } /* * Kick off an asynchronous reclaim of cached memory if one of the * page daemons is failing to keep up with demand. Use the "severe" * threshold instead of "min" to ensure that we do not blow away the * caches if a subset of the NUMA domains are depleted by kernel memory * allocations; the domainset iterators automatically skip domains * below the "min" threshold on the first pass. * * UMA reclaim worker has its own rate-limiting mechanism, so don't * worry about kicking it too often. */ if (vm_page_count_severe()) uma_reclaim_wakeup(); return (ret); } static void vm_pageout_worker(void *arg) { struct vm_domain *vmd; u_int ofree; int addl_shortage, domain, shortage; bool target_met; domain = (uintptr_t)arg; vmd = VM_DOMAIN(domain); shortage = 0; target_met = true; /* * XXXKIB It could be useful to bind pageout daemon threads to * the cores belonging to the domain, from which vm_page_array * is allocated. */ KASSERT(vmd->vmd_segs != 0, ("domain without segments")); vmd->vmd_last_active_scan = ticks; /* * The pageout daemon worker is never done, so loop forever. */ while (TRUE) { vm_domain_pageout_lock(vmd); /* * We need to clear wanted before we check the limits. This * prevents races with wakers who will check wanted after they * reach the limit. */ atomic_store_int(&vmd->vmd_pageout_wanted, 0); /* * Might the page daemon need to run again? */ if (vm_paging_needed(vmd, vmd->vmd_free_count)) { /* * Yes. If the scan failed to produce enough free * pages, sleep uninterruptibly for some time in the * hope that the laundry thread will clean some pages. */ vm_domain_pageout_unlock(vmd); if (!target_met) pause("pwait", hz / VM_INACT_SCAN_RATE); } else { /* * No, sleep until the next wakeup or until pages * need to have their reference stats updated. */ if (mtx_sleep(&vmd->vmd_pageout_wanted, vm_domain_pageout_lockptr(vmd), PDROP | PVM, "psleep", hz / VM_INACT_SCAN_RATE) == 0) VM_CNT_INC(v_pdwakeups); } /* Prevent spurious wakeups by ensuring that wanted is set. */ atomic_store_int(&vmd->vmd_pageout_wanted, 1); /* * Use the controller to calculate how many pages to free in * this interval, and scan the inactive queue. If the lowmem * handlers appear to have freed up some pages, subtract the * difference from the inactive queue scan target. */ shortage = pidctrl_daemon(&vmd->vmd_pid, vmd->vmd_free_count); if (shortage > 0) { ofree = vmd->vmd_free_count; if (vm_pageout_lowmem() && vmd->vmd_free_count > ofree) shortage -= min(vmd->vmd_free_count - ofree, (u_int)shortage); target_met = vm_pageout_inactive(vmd, shortage, &addl_shortage); } else addl_shortage = 0; /* * Scan the active queue. A positive value for shortage * indicates that we must aggressively deactivate pages to avoid * a shortfall. */ shortage = vm_pageout_active_target(vmd) + addl_shortage; vm_pageout_scan_active(vmd, shortage); } } /* * vm_pageout_helper runs additional pageout daemons in times of high paging * activity. */ static void vm_pageout_helper(void *arg) { struct vm_domain *vmd; int domain; domain = (uintptr_t)arg; vmd = VM_DOMAIN(domain); vm_domain_pageout_lock(vmd); for (;;) { msleep(&vmd->vmd_inactive_shortage, vm_domain_pageout_lockptr(vmd), PVM, "psleep", 0); blockcount_release(&vmd->vmd_inactive_starting, 1); vm_domain_pageout_unlock(vmd); vm_pageout_scan_inactive(vmd, vmd->vmd_inactive_shortage); vm_domain_pageout_lock(vmd); /* * Release the running count while the pageout lock is held to * prevent wakeup races. */ blockcount_release(&vmd->vmd_inactive_running, 1); } } static int get_pageout_threads_per_domain(const struct vm_domain *vmd) { unsigned total_pageout_threads, eligible_cpus, domain_cpus; if (VM_DOMAIN_EMPTY(vmd->vmd_domain)) return (0); /* * Semi-arbitrarily constrain pagedaemon threads to less than half the * total number of CPUs in the system as an upper limit. */ if (pageout_cpus_per_thread < 2) pageout_cpus_per_thread = 2; else if (pageout_cpus_per_thread > mp_ncpus) pageout_cpus_per_thread = mp_ncpus; total_pageout_threads = howmany(mp_ncpus, pageout_cpus_per_thread); domain_cpus = CPU_COUNT(&cpuset_domain[vmd->vmd_domain]); /* Pagedaemons are not run in empty domains. */ eligible_cpus = mp_ncpus; for (unsigned i = 0; i < vm_ndomains; i++) if (VM_DOMAIN_EMPTY(i)) eligible_cpus -= CPU_COUNT(&cpuset_domain[i]); /* * Assign a portion of the total pageout threads to this domain * corresponding to the fraction of pagedaemon-eligible CPUs in the * domain. In asymmetric NUMA systems, domains with more CPUs may be * allocated more threads than domains with fewer CPUs. */ return (howmany(total_pageout_threads * domain_cpus, eligible_cpus)); } /* * Initialize basic pageout daemon settings. See the comment above the * definition of vm_domain for some explanation of how these thresholds are * used. */ static void vm_pageout_init_domain(int domain) { struct vm_domain *vmd; struct sysctl_oid *oid; vmd = VM_DOMAIN(domain); vmd->vmd_interrupt_free_min = 2; /* * v_free_reserved needs to include enough for the largest * swap pager structures plus enough for any pv_entry structs * when paging. */ vmd->vmd_pageout_free_min = 2 * MAXBSIZE / PAGE_SIZE + vmd->vmd_interrupt_free_min; vmd->vmd_free_reserved = vm_pageout_page_count + vmd->vmd_pageout_free_min + vmd->vmd_page_count / 768; vmd->vmd_free_min = vmd->vmd_page_count / 200; vmd->vmd_free_severe = vmd->vmd_free_min / 2; vmd->vmd_free_target = 4 * vmd->vmd_free_min + vmd->vmd_free_reserved; vmd->vmd_free_min += vmd->vmd_free_reserved; vmd->vmd_free_severe += vmd->vmd_free_reserved; vmd->vmd_inactive_target = (3 * vmd->vmd_free_target) / 2; if (vmd->vmd_inactive_target > vmd->vmd_free_count / 3) vmd->vmd_inactive_target = vmd->vmd_free_count / 3; /* * Set the default wakeup threshold to be 10% below the paging * target. This keeps the steady state out of shortfall. */ vmd->vmd_pageout_wakeup_thresh = (vmd->vmd_free_target / 10) * 9; /* * Target amount of memory to move out of the laundry queue during a * background laundering. This is proportional to the amount of system * memory. */ vmd->vmd_background_launder_target = (vmd->vmd_free_target - vmd->vmd_free_min) / 10; /* Initialize the pageout daemon pid controller. */ pidctrl_init(&vmd->vmd_pid, hz / VM_INACT_SCAN_RATE, vmd->vmd_free_target, PIDCTRL_BOUND, PIDCTRL_KPD, PIDCTRL_KID, PIDCTRL_KDD); oid = SYSCTL_ADD_NODE(NULL, SYSCTL_CHILDREN(vmd->vmd_oid), OID_AUTO, "pidctrl", CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, ""); pidctrl_init_sysctl(&vmd->vmd_pid, SYSCTL_CHILDREN(oid)); vmd->vmd_inactive_threads = get_pageout_threads_per_domain(vmd); SYSCTL_ADD_BOOL(NULL, SYSCTL_CHILDREN(vmd->vmd_oid), OID_AUTO, "pageout_helper_threads_enabled", CTLFLAG_RWTUN, &vmd->vmd_helper_threads_enabled, 0, "Enable multi-threaded inactive queue scanning"); } static void vm_pageout_init(void) { u_long freecount; int i; /* * Initialize some paging parameters. */ freecount = 0; for (i = 0; i < vm_ndomains; i++) { struct vm_domain *vmd; vm_pageout_init_domain(i); vmd = VM_DOMAIN(i); vm_cnt.v_free_reserved += vmd->vmd_free_reserved; vm_cnt.v_free_target += vmd->vmd_free_target; vm_cnt.v_free_min += vmd->vmd_free_min; vm_cnt.v_inactive_target += vmd->vmd_inactive_target; vm_cnt.v_pageout_free_min += vmd->vmd_pageout_free_min; vm_cnt.v_interrupt_free_min += vmd->vmd_interrupt_free_min; vm_cnt.v_free_severe += vmd->vmd_free_severe; freecount += vmd->vmd_free_count; } /* * Set interval in seconds for active scan. We want to visit each * page at least once every ten minutes. This is to prevent worst * case paging behaviors with stale active LRU. */ if (vm_pageout_update_period == 0) vm_pageout_update_period = 600; /* * Set the maximum number of user-wired virtual pages. Historically the * main source of such pages was mlock(2) and mlockall(2). Hypervisors * may also request user-wired memory. */ if (vm_page_max_user_wired == 0) vm_page_max_user_wired = 4 * freecount / 5; } /* * vm_pageout is the high level pageout daemon. */ static void vm_pageout(void) { struct proc *p; struct thread *td; int error, first, i, j, pageout_threads; p = curproc; td = curthread; mtx_init(&vm_oom_ratelim_mtx, "vmoomr", NULL, MTX_DEF); swap_pager_swap_init(); for (first = -1, i = 0; i < vm_ndomains; i++) { if (VM_DOMAIN_EMPTY(i)) { if (bootverbose) printf("domain %d empty; skipping pageout\n", i); continue; } if (first == -1) first = i; else { error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, p, NULL, 0, 0, "dom%d", i); if (error != 0) panic("starting pageout for domain %d: %d\n", i, error); } pageout_threads = VM_DOMAIN(i)->vmd_inactive_threads; for (j = 0; j < pageout_threads - 1; j++) { error = kthread_add(vm_pageout_helper, (void *)(uintptr_t)i, p, NULL, 0, 0, "dom%d helper%d", i, j); if (error != 0) panic("starting pageout helper %d for domain " "%d: %d\n", j, i, error); } error = kthread_add(vm_pageout_laundry_worker, (void *)(uintptr_t)i, p, NULL, 0, 0, "laundry: dom%d", i); if (error != 0) panic("starting laundry for domain %d: %d", i, error); } error = kthread_add(uma_reclaim_worker, NULL, p, NULL, 0, 0, "uma"); if (error != 0) panic("starting uma_reclaim helper, error %d\n", error); snprintf(td->td_name, sizeof(td->td_name), "dom%d", first); vm_pageout_worker((void *)(uintptr_t)first); } /* * Perform an advisory wakeup of the page daemon. */ void pagedaemon_wakeup(int domain) { struct vm_domain *vmd; vmd = VM_DOMAIN(domain); vm_domain_pageout_assert_unlocked(vmd); if (curproc == pageproc) return; if (atomic_fetchadd_int(&vmd->vmd_pageout_wanted, 1) == 0) { vm_domain_pageout_lock(vmd); atomic_store_int(&vmd->vmd_pageout_wanted, 1); wakeup(&vmd->vmd_pageout_wanted); vm_domain_pageout_unlock(vmd); } }