1 /* $OpenBSD: uvm_anon.c,v 1.43 2014/12/23 04:56:47 tedu Exp $ */ 2 /* $NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 chs Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * uvm_anon.c: uvm anon ops 31 */ 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/malloc.h> 36 #include <sys/pool.h> 37 #include <sys/kernel.h> 38 #include <sys/atomic.h> 39 40 #include <uvm/uvm.h> 41 #include <uvm/uvm_swap.h> 42 43 struct pool uvm_anon_pool; 44 45 /* 46 * allocate anons 47 */ 48 void 49 uvm_anon_init(void) 50 { 51 pool_init(&uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 52 PR_WAITOK, "anonpl", NULL); 53 pool_sethiwat(&uvm_anon_pool, uvmexp.free / 16); 54 } 55 56 /* 57 * allocate an anon 58 */ 59 struct vm_anon * 60 uvm_analloc(void) 61 { 62 struct vm_anon *anon; 63 64 anon = pool_get(&uvm_anon_pool, PR_NOWAIT); 65 if (anon) { 66 anon->an_ref = 1; 67 anon->an_page = NULL; 68 anon->an_swslot = 0; 69 } 70 return(anon); 71 } 72 73 /* 74 * uvm_anfree: free a single anon structure 75 * 76 * => caller must remove anon from its amap before calling (if it was in 77 * an amap). 78 * => we may lock the pageq's. 79 */ 80 void 81 uvm_anfree(struct vm_anon *anon) 82 { 83 struct vm_page *pg; 84 85 /* get page */ 86 pg = anon->an_page; 87 88 /* 89 * if there is a resident page and it is loaned, then anon may not 90 * own it. call out to uvm_anon_lockpage() to ensure the real owner 91 * of the page has been identified and locked. 92 */ 93 if (pg && pg->loan_count) 94 pg = uvm_anon_lockloanpg(anon); 95 96 /* 97 * if we have a resident page, we must dispose of it before freeing 98 * the anon. 99 */ 100 if (pg) { 101 /* 102 * if the page is owned by a uobject, then we must 103 * kill the loan on the page rather than free it. 104 */ 105 if (pg->uobject) { 106 uvm_lock_pageq(); 107 KASSERT(pg->loan_count > 0); 108 pg->loan_count--; 109 pg->uanon = NULL; 110 uvm_unlock_pageq(); 111 } else { 112 /* 113 * page has no uobject, so we must be the owner of it. 114 * 115 * if page is busy then we just mark it as released 116 * (who ever has it busy must check for this when they 117 * wake up). if the page is not busy then we can 118 * free it now. 119 */ 120 if ((pg->pg_flags & PG_BUSY) != 0) { 121 /* tell them to dump it when done */ 122 atomic_setbits_int(&pg->pg_flags, PG_RELEASED); 123 return; 124 } 125 pmap_page_protect(pg, PROT_NONE); 126 uvm_lock_pageq(); /* lock out pagedaemon */ 127 uvm_pagefree(pg); /* bye bye */ 128 uvm_unlock_pageq(); /* free the daemon */ 129 } 130 } 131 if (pg == NULL && anon->an_swslot != 0) { 132 /* this page is no longer only in swap. */ 133 KASSERT(uvmexp.swpgonly > 0); 134 uvmexp.swpgonly--; 135 } 136 137 /* free any swap resources. */ 138 uvm_anon_dropswap(anon); 139 140 /* 141 * now that we've stripped the data areas from the anon, free the anon 142 * itself! 143 */ 144 KASSERT(anon->an_page == NULL); 145 KASSERT(anon->an_swslot == 0); 146 147 pool_put(&uvm_anon_pool, anon); 148 } 149 150 /* 151 * uvm_anon_dropswap: release any swap resources from this anon. 152 */ 153 void 154 uvm_anon_dropswap(struct vm_anon *anon) 155 { 156 157 if (anon->an_swslot == 0) 158 return; 159 160 uvm_swap_free(anon->an_swslot, 1); 161 anon->an_swslot = 0; 162 } 163 164 /* 165 * uvm_anon_lockloanpg: given a locked anon, lock its resident page 166 * 167 * => on return: 168 * if there is a resident page: 169 * if it is ownerless, we take over as owner 170 * we return the resident page (it can change during 171 * this function) 172 * => note that the only time an anon has an ownerless resident page 173 * is if the page was loaned from a uvm_object and the uvm_object 174 * disowned it 175 * => this only needs to be called when you want to do an operation 176 * on an anon's resident page and that page has a non-zero loan 177 * count. 178 */ 179 struct vm_page * 180 uvm_anon_lockloanpg(struct vm_anon *anon) 181 { 182 struct vm_page *pg; 183 184 /* 185 * loop while we have a resident page that has a non-zero loan count. 186 * if we successfully get our lock, we will "break" the loop. 187 * note that the test for pg->loan_count is not protected -- this 188 * may produce false positive results. note that a false positive 189 * result may cause us to do more work than we need to, but it will 190 * not produce an incorrect result. 191 */ 192 while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) { 193 /* 194 * if page is un-owned [i.e. the object dropped its ownership], 195 * then we can take over as owner! 196 */ 197 if (pg->uobject == NULL && (pg->pg_flags & PQ_ANON) == 0) { 198 uvm_lock_pageq(); 199 atomic_setbits_int(&pg->pg_flags, PQ_ANON); 200 pg->loan_count--; /* ... and drop our loan */ 201 uvm_unlock_pageq(); 202 } 203 break; 204 } 205 return(pg); 206 } 207 208 /* 209 * fetch an anon's page. 210 * 211 * => returns TRUE if pagein was aborted due to lack of memory. 212 */ 213 214 boolean_t 215 uvm_anon_pagein(struct vm_anon *anon) 216 { 217 struct vm_page *pg; 218 struct uvm_object *uobj; 219 int rv; 220 221 rv = uvmfault_anonget(NULL, NULL, anon); 222 223 switch (rv) { 224 case VM_PAGER_OK: 225 break; 226 case VM_PAGER_ERROR: 227 case VM_PAGER_REFAULT: 228 /* 229 * nothing more to do on errors. 230 * VM_PAGER_REFAULT can only mean that the anon was freed, 231 * so again there's nothing to do. 232 */ 233 return FALSE; 234 default: 235 #ifdef DIAGNOSTIC 236 panic("anon_pagein: uvmfault_anonget -> %d", rv); 237 #else 238 return FALSE; 239 #endif 240 } 241 242 /* 243 * ok, we've got the page now. 244 * mark it as dirty, clear its swslot and un-busy it. 245 */ 246 pg = anon->an_page; 247 uobj = pg->uobject; 248 uvm_swap_free(anon->an_swslot, 1); 249 anon->an_swslot = 0; 250 atomic_clearbits_int(&pg->pg_flags, PG_CLEAN); 251 252 /* deactivate the page (to put it on a page queue) */ 253 pmap_clear_reference(pg); 254 pmap_page_protect(pg, PROT_NONE); 255 uvm_lock_pageq(); 256 uvm_pagedeactivate(pg); 257 uvm_unlock_pageq(); 258 259 return FALSE; 260 } 261