The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_phys.c

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    1 /*-
    2  * Copyright (c) 2002-2006 Rice University
    3  * Copyright (c) 2007 Alan L. Cox <alc@cs.rice.edu>
    4  * All rights reserved.
    5  *
    6  * This software was developed for the FreeBSD Project by Alan L. Cox,
    7  * Olivier Crameri, Peter Druschel, Sitaram Iyer, and Juan Navarro.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   21  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
   22  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   25  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
   28  * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   29  * POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD$");
   34 
   35 #include "opt_ddb.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/lock.h>
   40 #include <sys/kernel.h>
   41 #include <sys/malloc.h>
   42 #include <sys/mutex.h>
   43 #include <sys/queue.h>
   44 #include <sys/sbuf.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/vmmeter.h>
   47 #include <sys/vnode.h>
   48 
   49 #include <ddb/ddb.h>
   50 
   51 #include <vm/vm.h>
   52 #include <vm/vm_param.h>
   53 #include <vm/vm_kern.h>
   54 #include <vm/vm_object.h>
   55 #include <vm/vm_page.h>
   56 #include <vm/vm_phys.h>
   57 #include <vm/vm_reserv.h>
   58 
   59 struct vm_freelist {
   60         struct pglist pl;
   61         int lcnt;
   62 };
   63 
   64 struct vm_phys_seg {
   65         vm_paddr_t      start;
   66         vm_paddr_t      end;
   67         vm_page_t       first_page;
   68         struct vm_freelist (*free_queues)[VM_NFREEPOOL][VM_NFREEORDER];
   69 };
   70 
   71 static struct vm_phys_seg vm_phys_segs[VM_PHYSSEG_MAX];
   72 
   73 static int vm_phys_nsegs;
   74 
   75 static struct vm_freelist
   76     vm_phys_free_queues[VM_NFREELIST][VM_NFREEPOOL][VM_NFREEORDER];
   77 
   78 static int vm_nfreelists = VM_FREELIST_DEFAULT + 1;
   79 
   80 static int cnt_prezero;
   81 SYSCTL_INT(_vm_stats_misc, OID_AUTO, cnt_prezero, CTLFLAG_RD,
   82     &cnt_prezero, 0, "The number of physical pages prezeroed at idle time");
   83 
   84 static int sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS);
   85 SYSCTL_OID(_vm, OID_AUTO, phys_free, CTLTYPE_STRING | CTLFLAG_RD,
   86     NULL, 0, sysctl_vm_phys_free, "A", "Phys Free Info");
   87 
   88 static int sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS);
   89 SYSCTL_OID(_vm, OID_AUTO, phys_segs, CTLTYPE_STRING | CTLFLAG_RD,
   90     NULL, 0, sysctl_vm_phys_segs, "A", "Phys Seg Info");
   91 
   92 static void vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int flind);
   93 static int vm_phys_paddr_to_segind(vm_paddr_t pa);
   94 static void vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl,
   95     int order);
   96 
   97 /*
   98  * Outputs the state of the physical memory allocator, specifically,
   99  * the amount of physical memory in each free list.
  100  */
  101 static int
  102 sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS)
  103 {
  104         struct sbuf sbuf;
  105         struct vm_freelist *fl;
  106         char *cbuf;
  107         const int cbufsize = vm_nfreelists*(VM_NFREEORDER + 1)*81;
  108         int error, flind, oind, pind;
  109 
  110         cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
  111         sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
  112         for (flind = 0; flind < vm_nfreelists; flind++) {
  113                 sbuf_printf(&sbuf, "\nFREE LIST %d:\n"
  114                     "\n  ORDER (SIZE)  |  NUMBER"
  115                     "\n              ", flind);
  116                 for (pind = 0; pind < VM_NFREEPOOL; pind++)
  117                         sbuf_printf(&sbuf, "  |  POOL %d", pind);
  118                 sbuf_printf(&sbuf, "\n--            ");
  119                 for (pind = 0; pind < VM_NFREEPOOL; pind++)
  120                         sbuf_printf(&sbuf, "-- --      ");
  121                 sbuf_printf(&sbuf, "--\n");
  122                 for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
  123                         sbuf_printf(&sbuf, "  %2.2d (%6.6dK)", oind,
  124                             1 << (PAGE_SHIFT - 10 + oind));
  125                         for (pind = 0; pind < VM_NFREEPOOL; pind++) {
  126                                 fl = vm_phys_free_queues[flind][pind];
  127                                 sbuf_printf(&sbuf, "  |  %6.6d", fl[oind].lcnt);
  128                         }
  129                         sbuf_printf(&sbuf, "\n");
  130                 }
  131         }
  132         sbuf_finish(&sbuf);
  133         error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
  134         sbuf_delete(&sbuf);
  135         free(cbuf, M_TEMP);
  136         return (error);
  137 }
  138 
  139 /*
  140  * Outputs the set of physical memory segments.
  141  */
  142 static int
  143 sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS)
  144 {
  145         struct sbuf sbuf;
  146         struct vm_phys_seg *seg;
  147         char *cbuf;
  148         const int cbufsize = VM_PHYSSEG_MAX*(VM_NFREEORDER + 1)*81;
  149         int error, segind;
  150 
  151         cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
  152         sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
  153         for (segind = 0; segind < vm_phys_nsegs; segind++) {
  154                 sbuf_printf(&sbuf, "\nSEGMENT %d:\n\n", segind);
  155                 seg = &vm_phys_segs[segind];
  156                 sbuf_printf(&sbuf, "start:     %#jx\n",
  157                     (uintmax_t)seg->start);
  158                 sbuf_printf(&sbuf, "end:       %#jx\n",
  159                     (uintmax_t)seg->end);
  160                 sbuf_printf(&sbuf, "free list: %p\n", seg->free_queues);
  161         }
  162         sbuf_finish(&sbuf);
  163         error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
  164         sbuf_delete(&sbuf);
  165         free(cbuf, M_TEMP);
  166         return (error);
  167 }
  168 
  169 /*
  170  * Create a physical memory segment.
  171  */
  172 static void
  173 vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int flind)
  174 {
  175         struct vm_phys_seg *seg;
  176 #ifdef VM_PHYSSEG_SPARSE
  177         long pages;
  178         int segind;
  179 
  180         pages = 0;
  181         for (segind = 0; segind < vm_phys_nsegs; segind++) {
  182                 seg = &vm_phys_segs[segind];
  183                 pages += atop(seg->end - seg->start);
  184         }
  185 #endif
  186         KASSERT(vm_phys_nsegs < VM_PHYSSEG_MAX,
  187             ("vm_phys_create_seg: increase VM_PHYSSEG_MAX"));
  188         seg = &vm_phys_segs[vm_phys_nsegs++];
  189         seg->start = start;
  190         seg->end = end;
  191 #ifdef VM_PHYSSEG_SPARSE
  192         seg->first_page = &vm_page_array[pages];
  193 #else
  194         seg->first_page = PHYS_TO_VM_PAGE(start);
  195 #endif
  196         seg->free_queues = &vm_phys_free_queues[flind];
  197 }
  198 
  199 /*
  200  * Initialize the physical memory allocator.
  201  */
  202 void
  203 vm_phys_init(void)
  204 {
  205         struct vm_freelist *fl;
  206         int flind, i, oind, pind;
  207 
  208         for (i = 0; phys_avail[i + 1] != 0; i += 2) {
  209 #ifdef  VM_FREELIST_ISADMA
  210                 if (phys_avail[i] < 16777216) {
  211                         if (phys_avail[i + 1] > 16777216) {
  212                                 vm_phys_create_seg(phys_avail[i], 16777216,
  213                                     VM_FREELIST_ISADMA);
  214                                 vm_phys_create_seg(16777216, phys_avail[i + 1],
  215                                     VM_FREELIST_DEFAULT);
  216                         } else {
  217                                 vm_phys_create_seg(phys_avail[i],
  218                                     phys_avail[i + 1], VM_FREELIST_ISADMA);
  219                         }
  220                         if (VM_FREELIST_ISADMA >= vm_nfreelists)
  221                                 vm_nfreelists = VM_FREELIST_ISADMA + 1;
  222                 } else
  223 #endif
  224 #ifdef  VM_FREELIST_HIGHMEM
  225                 if (phys_avail[i + 1] > VM_HIGHMEM_ADDRESS) {
  226                         if (phys_avail[i] < VM_HIGHMEM_ADDRESS) {
  227                                 vm_phys_create_seg(phys_avail[i],
  228                                     VM_HIGHMEM_ADDRESS, VM_FREELIST_DEFAULT);
  229                                 vm_phys_create_seg(VM_HIGHMEM_ADDRESS,
  230                                     phys_avail[i + 1], VM_FREELIST_HIGHMEM);
  231                         } else {
  232                                 vm_phys_create_seg(phys_avail[i],
  233                                     phys_avail[i + 1], VM_FREELIST_HIGHMEM);
  234                         }
  235                         if (VM_FREELIST_HIGHMEM >= vm_nfreelists)
  236                                 vm_nfreelists = VM_FREELIST_HIGHMEM + 1;
  237                 } else
  238 #endif
  239                 vm_phys_create_seg(phys_avail[i], phys_avail[i + 1],
  240                     VM_FREELIST_DEFAULT);
  241         }
  242         for (flind = 0; flind < vm_nfreelists; flind++) {
  243                 for (pind = 0; pind < VM_NFREEPOOL; pind++) {
  244                         fl = vm_phys_free_queues[flind][pind];
  245                         for (oind = 0; oind < VM_NFREEORDER; oind++)
  246                                 TAILQ_INIT(&fl[oind].pl);
  247                 }
  248         }
  249 }
  250 
  251 /*
  252  * Split a contiguous, power of two-sized set of physical pages.
  253  */
  254 static __inline void
  255 vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl, int order)
  256 {
  257         vm_page_t m_buddy;
  258 
  259         while (oind > order) {
  260                 oind--;
  261                 m_buddy = &m[1 << oind];
  262                 KASSERT(m_buddy->order == VM_NFREEORDER,
  263                     ("vm_phys_split_pages: page %p has unexpected order %d",
  264                     m_buddy, m_buddy->order));
  265                 m_buddy->order = oind;
  266                 TAILQ_INSERT_HEAD(&fl[oind].pl, m_buddy, pageq);
  267                 fl[oind].lcnt++;
  268         }
  269 }
  270 
  271 /*
  272  * Initialize a physical page and add it to the free lists.
  273  */
  274 void
  275 vm_phys_add_page(vm_paddr_t pa)
  276 {
  277         vm_page_t m;
  278 
  279         cnt.v_page_count++;
  280         m = vm_phys_paddr_to_vm_page(pa);
  281         m->phys_addr = pa;
  282         m->segind = vm_phys_paddr_to_segind(pa);
  283         m->flags = PG_FREE;
  284         KASSERT(m->order == VM_NFREEORDER,
  285             ("vm_phys_add_page: page %p has unexpected order %d",
  286             m, m->order));
  287         m->pool = VM_FREEPOOL_DEFAULT;
  288         pmap_page_init(m);
  289         mtx_lock(&vm_page_queue_free_mtx);
  290         cnt.v_free_count++;
  291         vm_phys_free_pages(m, 0);
  292         mtx_unlock(&vm_page_queue_free_mtx);
  293 }
  294 
  295 /*
  296  * Allocate a contiguous, power of two-sized set of physical pages
  297  * from the free lists.
  298  *
  299  * The free page queues must be locked.
  300  */
  301 vm_page_t
  302 vm_phys_alloc_pages(int pool, int order)
  303 {
  304         struct vm_freelist *fl;
  305         struct vm_freelist *alt;
  306         int flind, oind, pind;
  307         vm_page_t m;
  308 
  309         KASSERT(pool < VM_NFREEPOOL,
  310             ("vm_phys_alloc_pages: pool %d is out of range", pool));
  311         KASSERT(order < VM_NFREEORDER,
  312             ("vm_phys_alloc_pages: order %d is out of range", order));
  313         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
  314         for (flind = 0; flind < vm_nfreelists; flind++) {
  315                 fl = vm_phys_free_queues[flind][pool];
  316                 for (oind = order; oind < VM_NFREEORDER; oind++) {
  317                         m = TAILQ_FIRST(&fl[oind].pl);
  318                         if (m != NULL) {
  319                                 TAILQ_REMOVE(&fl[oind].pl, m, pageq);
  320                                 fl[oind].lcnt--;
  321                                 m->order = VM_NFREEORDER;
  322                                 vm_phys_split_pages(m, oind, fl, order);
  323                                 return (m);
  324                         }
  325                 }
  326 
  327                 /*
  328                  * The given pool was empty.  Find the largest
  329                  * contiguous, power-of-two-sized set of pages in any
  330                  * pool.  Transfer these pages to the given pool, and
  331                  * use them to satisfy the allocation.
  332                  */
  333                 for (oind = VM_NFREEORDER - 1; oind >= order; oind--) {
  334                         for (pind = 0; pind < VM_NFREEPOOL; pind++) {
  335                                 alt = vm_phys_free_queues[flind][pind];
  336                                 m = TAILQ_FIRST(&alt[oind].pl);
  337                                 if (m != NULL) {
  338                                         TAILQ_REMOVE(&alt[oind].pl, m, pageq);
  339                                         alt[oind].lcnt--;
  340                                         m->order = VM_NFREEORDER;
  341                                         vm_phys_set_pool(pool, m, oind);
  342                                         vm_phys_split_pages(m, oind, fl, order);
  343                                         return (m);
  344                                 }
  345                         }
  346                 }
  347         }
  348         return (NULL);
  349 }
  350 
  351 /*
  352  * Allocate physical memory from phys_avail[].
  353  */
  354 vm_paddr_t
  355 vm_phys_bootstrap_alloc(vm_size_t size, unsigned long alignment)
  356 {
  357         vm_paddr_t pa;
  358         int i;
  359 
  360         size = round_page(size);
  361         for (i = 0; phys_avail[i + 1] != 0; i += 2) {
  362                 if (phys_avail[i + 1] - phys_avail[i] < size)
  363                         continue;
  364                 pa = phys_avail[i];
  365                 phys_avail[i] += size;
  366                 return (pa);
  367         }
  368         panic("vm_phys_bootstrap_alloc");
  369 }
  370 
  371 /*
  372  * Find the vm_page corresponding to the given physical address.
  373  */
  374 vm_page_t
  375 vm_phys_paddr_to_vm_page(vm_paddr_t pa)
  376 {
  377         struct vm_phys_seg *seg;
  378         int segind;
  379 
  380         for (segind = 0; segind < vm_phys_nsegs; segind++) {
  381                 seg = &vm_phys_segs[segind];
  382                 if (pa >= seg->start && pa < seg->end)
  383                         return (&seg->first_page[atop(pa - seg->start)]);
  384         }
  385         panic("vm_phys_paddr_to_vm_page: paddr %#jx is not in any segment",
  386             (uintmax_t)pa);
  387 }
  388 
  389 /*
  390  * Find the segment containing the given physical address.
  391  */
  392 static int
  393 vm_phys_paddr_to_segind(vm_paddr_t pa)
  394 {
  395         struct vm_phys_seg *seg;
  396         int segind;
  397 
  398         for (segind = 0; segind < vm_phys_nsegs; segind++) {
  399                 seg = &vm_phys_segs[segind];
  400                 if (pa >= seg->start && pa < seg->end)
  401                         return (segind);
  402         }
  403         panic("vm_phys_paddr_to_segind: paddr %#jx is not in any segment" ,
  404             (uintmax_t)pa);
  405 }
  406 
  407 /*
  408  * Free a contiguous, power of two-sized set of physical pages.
  409  *
  410  * The free page queues must be locked.
  411  */
  412 void
  413 vm_phys_free_pages(vm_page_t m, int order)
  414 {
  415         struct vm_freelist *fl;
  416         struct vm_phys_seg *seg;
  417         vm_paddr_t pa, pa_buddy;
  418         vm_page_t m_buddy;
  419 
  420         KASSERT(m->order == VM_NFREEORDER,
  421             ("vm_phys_free_pages: page %p has unexpected order %d",
  422             m, m->order));
  423         KASSERT(m->pool < VM_NFREEPOOL,
  424             ("vm_phys_free_pages: page %p has unexpected pool %d",
  425             m, m->pool));
  426         KASSERT(order < VM_NFREEORDER,
  427             ("vm_phys_free_pages: order %d is out of range", order));
  428         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
  429         pa = VM_PAGE_TO_PHYS(m);
  430         seg = &vm_phys_segs[m->segind];
  431         while (order < VM_NFREEORDER - 1) {
  432                 pa_buddy = pa ^ (1 << (PAGE_SHIFT + order));
  433                 if (pa_buddy < seg->start ||
  434                     pa_buddy >= seg->end)
  435                         break;
  436                 m_buddy = &seg->first_page[atop(pa_buddy - seg->start)];
  437                 if (m_buddy->order != order)
  438                         break;
  439                 fl = (*seg->free_queues)[m_buddy->pool];
  440                 TAILQ_REMOVE(&fl[m_buddy->order].pl, m_buddy, pageq);
  441                 fl[m_buddy->order].lcnt--;
  442                 m_buddy->order = VM_NFREEORDER;
  443                 if (m_buddy->pool != m->pool)
  444                         vm_phys_set_pool(m->pool, m_buddy, order);
  445                 order++;
  446                 pa &= ~((1 << (PAGE_SHIFT + order)) - 1);
  447                 m = &seg->first_page[atop(pa - seg->start)];
  448         }
  449         m->order = order;
  450         fl = (*seg->free_queues)[m->pool];
  451         TAILQ_INSERT_TAIL(&fl[order].pl, m, pageq);
  452         fl[order].lcnt++;
  453 }
  454 
  455 /*
  456  * Set the pool for a contiguous, power of two-sized set of physical pages. 
  457  */
  458 void
  459 vm_phys_set_pool(int pool, vm_page_t m, int order)
  460 {
  461         vm_page_t m_tmp;
  462 
  463         for (m_tmp = m; m_tmp < &m[1 << order]; m_tmp++)
  464                 m_tmp->pool = pool;
  465 }
  466 
  467 /*
  468  * Search for the given physical page "m" in the free lists.  If the search
  469  * succeeds, remove "m" from the free lists and return TRUE.  Otherwise, return
  470  * FALSE, indicating that "m" is not in the free lists.
  471  *
  472  * The free page queues must be locked.
  473  */
  474 boolean_t
  475 vm_phys_unfree_page(vm_page_t m)
  476 {
  477         struct vm_freelist *fl;
  478         struct vm_phys_seg *seg;
  479         vm_paddr_t pa, pa_half;
  480         vm_page_t m_set, m_tmp;
  481         int order;
  482 
  483         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
  484 
  485         /*
  486          * First, find the contiguous, power of two-sized set of free
  487          * physical pages containing the given physical page "m" and
  488          * assign it to "m_set".
  489          */
  490         seg = &vm_phys_segs[m->segind];
  491         for (m_set = m, order = 0; m_set->order == VM_NFREEORDER &&
  492             order < VM_NFREEORDER - 1; ) {
  493                 order++;
  494                 pa = m->phys_addr & (~(vm_paddr_t)0 << (PAGE_SHIFT + order));
  495                 if (pa >= seg->start)
  496                         m_set = &seg->first_page[atop(pa - seg->start)];
  497                 else
  498                         return (FALSE);
  499         }
  500         if (m_set->order < order)
  501                 return (FALSE);
  502         if (m_set->order == VM_NFREEORDER)
  503                 return (FALSE);
  504         KASSERT(m_set->order < VM_NFREEORDER,
  505             ("vm_phys_unfree_page: page %p has unexpected order %d",
  506             m_set, m_set->order));
  507 
  508         /*
  509          * Next, remove "m_set" from the free lists.  Finally, extract
  510          * "m" from "m_set" using an iterative algorithm: While "m_set"
  511          * is larger than a page, shrink "m_set" by returning the half
  512          * of "m_set" that does not contain "m" to the free lists.
  513          */
  514         fl = (*seg->free_queues)[m_set->pool];
  515         order = m_set->order;
  516         TAILQ_REMOVE(&fl[order].pl, m_set, pageq);
  517         fl[order].lcnt--;
  518         m_set->order = VM_NFREEORDER;
  519         while (order > 0) {
  520                 order--;
  521                 pa_half = m_set->phys_addr ^ (1 << (PAGE_SHIFT + order));
  522                 if (m->phys_addr < pa_half)
  523                         m_tmp = &seg->first_page[atop(pa_half - seg->start)];
  524                 else {
  525                         m_tmp = m_set;
  526                         m_set = &seg->first_page[atop(pa_half - seg->start)];
  527                 }
  528                 m_tmp->order = order;
  529                 TAILQ_INSERT_HEAD(&fl[order].pl, m_tmp, pageq);
  530                 fl[order].lcnt++;
  531         }
  532         KASSERT(m_set == m, ("vm_phys_unfree_page: fatal inconsistency"));
  533         return (TRUE);
  534 }
  535 
  536 /*
  537  * Try to zero one physical page.  Used by an idle priority thread.
  538  */
  539 boolean_t
  540 vm_phys_zero_pages_idle(void)
  541 {
  542         static struct vm_freelist *fl = vm_phys_free_queues[0][0];
  543         static int flind, oind, pind;
  544         vm_page_t m, m_tmp;
  545 
  546         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
  547         for (;;) {
  548                 TAILQ_FOREACH_REVERSE(m, &fl[oind].pl, pglist, pageq) {
  549                         for (m_tmp = m; m_tmp < &m[1 << oind]; m_tmp++) {
  550                                 if ((m_tmp->flags & (PG_CACHED | PG_ZERO)) == 0) {
  551                                         vm_phys_unfree_page(m_tmp);
  552                                         cnt.v_free_count--;
  553                                         mtx_unlock(&vm_page_queue_free_mtx);
  554                                         pmap_zero_page_idle(m_tmp);
  555                                         m_tmp->flags |= PG_ZERO;
  556                                         mtx_lock(&vm_page_queue_free_mtx);
  557                                         cnt.v_free_count++;
  558                                         vm_phys_free_pages(m_tmp, 0);
  559                                         vm_page_zero_count++;
  560                                         cnt_prezero++;
  561                                         return (TRUE);
  562                                 }
  563                         }
  564                 }
  565                 oind++;
  566                 if (oind == VM_NFREEORDER) {
  567                         oind = 0;
  568                         pind++;
  569                         if (pind == VM_NFREEPOOL) {
  570                                 pind = 0;
  571                                 flind++;
  572                                 if (flind == vm_nfreelists)
  573                                         flind = 0;
  574                         }
  575                         fl = vm_phys_free_queues[flind][pind];
  576                 }
  577         }
  578 }
  579 
  580 /*
  581  * Allocate a contiguous set of physical pages of the given size
  582  * "npages" from the free lists.  All of the physical pages must be at
  583  * or above the given physical address "low" and below the given
  584  * physical address "high".  The given value "alignment" determines the
  585  * alignment of the first physical page in the set.  If the given value
  586  * "boundary" is non-zero, then the set of physical pages cannot cross
  587  * any physical address boundary that is a multiple of that value.  Both
  588  * "alignment" and "boundary" must be a power of two.
  589  */
  590 vm_page_t
  591 vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high,
  592     unsigned long alignment, unsigned long boundary)
  593 {
  594         struct vm_freelist *fl;
  595         struct vm_phys_seg *seg;
  596         vm_object_t m_object;
  597         vm_paddr_t pa, pa_last, size;
  598         vm_page_t m, m_ret;
  599         int flind, i, oind, order, pind;
  600 
  601         size = npages << PAGE_SHIFT;
  602         KASSERT(size != 0,
  603             ("vm_phys_alloc_contig: size must not be 0"));
  604         KASSERT((alignment & (alignment - 1)) == 0,
  605             ("vm_phys_alloc_contig: alignment must be a power of 2"));
  606         KASSERT((boundary & (boundary - 1)) == 0,
  607             ("vm_phys_alloc_contig: boundary must be a power of 2"));
  608         /* Compute the queue that is the best fit for npages. */
  609         for (order = 0; (1 << order) < npages; order++);
  610         mtx_lock(&vm_page_queue_free_mtx);
  611 #if VM_NRESERVLEVEL > 0
  612 retry:
  613 #endif
  614         for (flind = 0; flind < vm_nfreelists; flind++) {
  615                 for (oind = min(order, VM_NFREEORDER - 1); oind < VM_NFREEORDER; oind++) {
  616                         for (pind = 0; pind < VM_NFREEPOOL; pind++) {
  617                                 fl = vm_phys_free_queues[flind][pind];
  618                                 TAILQ_FOREACH(m_ret, &fl[oind].pl, pageq) {
  619                                         /*
  620                                          * A free list may contain physical pages
  621                                          * from one or more segments.
  622                                          */
  623                                         seg = &vm_phys_segs[m_ret->segind];
  624                                         if (seg->start > high ||
  625                                             low >= seg->end)
  626                                                 continue;
  627 
  628                                         /*
  629                                          * Is the size of this allocation request
  630                                          * larger than the largest block size?
  631                                          */
  632                                         if (order >= VM_NFREEORDER) {
  633                                                 /*
  634                                                  * Determine if a sufficient number
  635                                                  * of subsequent blocks to satisfy
  636                                                  * the allocation request are free.
  637                                                  */
  638                                                 pa = VM_PAGE_TO_PHYS(m_ret);
  639                                                 pa_last = pa + size;
  640                                                 for (;;) {
  641                                                         pa += 1 << (PAGE_SHIFT + VM_NFREEORDER - 1);
  642                                                         if (pa >= pa_last)
  643                                                                 break;
  644                                                         if (pa < seg->start ||
  645                                                             pa >= seg->end)
  646                                                                 break;
  647                                                         m = &seg->first_page[atop(pa - seg->start)];
  648                                                         if (m->order != VM_NFREEORDER - 1)
  649                                                                 break;
  650                                                 }
  651                                                 /* If not, continue to the next block. */
  652                                                 if (pa < pa_last)
  653                                                         continue;
  654                                         }
  655 
  656                                         /*
  657                                          * Determine if the blocks are within the given range,
  658                                          * satisfy the given alignment, and do not cross the
  659                                          * given boundary.
  660                                          */
  661                                         pa = VM_PAGE_TO_PHYS(m_ret);
  662                                         if (pa >= low &&
  663                                             pa + size <= high &&
  664                                             (pa & (alignment - 1)) == 0 &&
  665                                             ((pa ^ (pa + size - 1)) & ~(boundary - 1)) == 0)
  666                                                 goto done;
  667                                 }
  668                         }
  669                 }
  670         }
  671 #if VM_NRESERVLEVEL > 0
  672         if (vm_reserv_reclaim_contig(size, low, high, alignment, boundary))
  673                 goto retry;
  674 #endif
  675         mtx_unlock(&vm_page_queue_free_mtx);
  676         return (NULL);
  677 done:
  678         for (m = m_ret; m < &m_ret[npages]; m = &m[1 << oind]) {
  679                 fl = (*seg->free_queues)[m->pool];
  680                 TAILQ_REMOVE(&fl[m->order].pl, m, pageq);
  681                 fl[m->order].lcnt--;
  682                 m->order = VM_NFREEORDER;
  683         }
  684         if (m_ret->pool != VM_FREEPOOL_DEFAULT)
  685                 vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m_ret, oind);
  686         fl = (*seg->free_queues)[m_ret->pool];
  687         vm_phys_split_pages(m_ret, oind, fl, order);
  688         for (i = 0; i < npages; i++) {
  689                 m = &m_ret[i];
  690                 KASSERT(m->queue == PQ_NONE,
  691                     ("vm_phys_alloc_contig: page %p has unexpected queue %d",
  692                     m, m->queue));
  693                 m_object = m->object;
  694                 if ((m->flags & PG_CACHED) != 0)
  695                         vm_page_cache_remove(m);
  696                 else {
  697                         KASSERT(VM_PAGE_IS_FREE(m),
  698                             ("vm_phys_alloc_contig: page %p is not free", m));
  699                         cnt.v_free_count--;
  700                 }
  701                 m->valid = VM_PAGE_BITS_ALL;
  702                 if (m->flags & PG_ZERO)
  703                         vm_page_zero_count--;
  704                 /* Don't clear the PG_ZERO flag; we'll need it later. */
  705                 m->flags = PG_UNMANAGED | (m->flags & PG_ZERO);
  706                 m->oflags = 0;
  707                 KASSERT(m->dirty == 0,
  708                     ("vm_phys_alloc_contig: page %p was dirty", m));
  709                 m->wire_count = 0;
  710                 m->busy = 0;
  711                 if (m_object != NULL &&
  712                     m_object->type == OBJT_VNODE &&
  713                     m_object->cache == NULL) {
  714                         mtx_unlock(&vm_page_queue_free_mtx);
  715                         vdrop(m_object->handle);
  716                         mtx_lock(&vm_page_queue_free_mtx);
  717                 }
  718         }
  719         for (; i < roundup2(npages, 1 << imin(oind, order)); i++) {
  720                 m = &m_ret[i];
  721                 KASSERT(m->order == VM_NFREEORDER,
  722                     ("vm_phys_alloc_contig: page %p has unexpected order %d",
  723                     m, m->order));
  724                 vm_phys_free_pages(m, 0);
  725         }
  726         mtx_unlock(&vm_page_queue_free_mtx);
  727         return (m_ret);
  728 }
  729 
  730 #ifdef DDB
  731 /*
  732  * Show the number of physical pages in each of the free lists.
  733  */
  734 DB_SHOW_COMMAND(freepages, db_show_freepages)
  735 {
  736         struct vm_freelist *fl;
  737         int flind, oind, pind;
  738 
  739         for (flind = 0; flind < vm_nfreelists; flind++) {
  740                 db_printf("FREE LIST %d:\n"
  741                     "\n  ORDER (SIZE)  |  NUMBER"
  742                     "\n              ", flind);
  743                 for (pind = 0; pind < VM_NFREEPOOL; pind++)
  744                         db_printf("  |  POOL %d", pind);
  745                 db_printf("\n--            ");
  746                 for (pind = 0; pind < VM_NFREEPOOL; pind++)
  747                         db_printf("-- --      ");
  748                 db_printf("--\n");
  749                 for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
  750                         db_printf("  %2.2d (%6.6dK)", oind,
  751                             1 << (PAGE_SHIFT - 10 + oind));
  752                         for (pind = 0; pind < VM_NFREEPOOL; pind++) {
  753                                 fl = vm_phys_free_queues[flind][pind];
  754                                 db_printf("  |  %6.6d", fl[oind].lcnt);
  755                         }
  756                         db_printf("\n");
  757                 }
  758                 db_printf("\n");
  759         }
  760 }
  761 #endif

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