sys/vm/vm_radix.c

   1 /*
   2  * Copyright (c) 2013 EMC Corp.
   3  * Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org>
   4  * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  */
  29
  30 /*
  31  * Path-compressed radix trie implementation.
  32  * The following code is not generalized into a general purpose library
  33  * because there are way too many parameters embedded that should really
  34  * be decided by the library consumers.  At the same time, consumers
  35  * of this code must achieve highest possible performance.
  36  *
  37  * The implementation takes into account the following rationale:
  38  * - Size of the nodes should be as small as possible but still big enough
  39  *   to avoid a large maximum depth for the trie.  This is a balance
  40  *   between the necessity to not wire too much physical memory for the nodes
  41  *   and the necessity to avoid too much cache pollution during the trie
  42  *   operations.
  43  * - There is not a huge bias toward the number of lookup operations over
  44  *   the number of insert and remove operations.  This basically implies
  45  *   that optimizations supposedly helping one operation but hurting the
  46  *   other might be carefully evaluated.
  47  * - On average not many nodes are expected to be fully populated, hence
  48  *   level compression may just complicate things.
  49  */
  50
  51 #include <sys/cdefs.h>
  52 __FBSDID("$FreeBSD$");
  53
  54 #include "opt_ddb.h"
  55
  56 #include <sys/param.h>
  57 #include <sys/systm.h>
  58 #include <sys/kernel.h>
  59 #include <sys/vmmeter.h>
  60
  61 #include <vm/uma.h>
  62 #include <vm/vm.h>
  63 #include <vm/vm_param.h>
  64 #include <vm/vm_page.h>
  65 #include <vm/vm_radix.h>
  66
  67 #ifdef DDB
  68 #include <ddb/ddb.h>
  69 #endif
  70
  71 /*
  72  * These widths should allow the pointers to a node's children to fit within
  73  * a single cache line.  The extra levels from a narrow width should not be
  74  * a problem thanks to path compression.
  75  */
  76 #ifdef __LP64__
  77 #define VM_RADIX_WIDTH  4
  78 #else
  79 #define VM_RADIX_WIDTH  3
  80 #endif
  81
  82 #define VM_RADIX_COUNT  (1 << VM_RADIX_WIDTH)
  83 #define VM_RADIX_MASK   (VM_RADIX_COUNT - 1)
  84 #define VM_RADIX_LIMIT                                                  \
  85         (howmany((sizeof(vm_pindex_t) * NBBY), VM_RADIX_WIDTH) - 1)
  86
  87 /* Flag bits stored in node pointers. */
  88 #define VM_RADIX_ISLEAF 0x1
  89 #define VM_RADIX_FLAGS  0x1
  90 #define VM_RADIX_PAD    VM_RADIX_FLAGS
  91
  92 /* Returns one unit associated with specified level. */
  93 #define VM_RADIX_UNITLEVEL(lev)                                         \
  94         ((vm_pindex_t)1 << ((VM_RADIX_LIMIT - (lev)) * VM_RADIX_WIDTH))
  95
  96 struct vm_radix_node {
  97         vm_pindex_t      rn_owner;                      /* Owner of record. */
  98         uint16_t         rn_count;                      /* Valid children. */
  99         uint16_t         rn_clev;                       /* Current level. */
 100         void            *rn_child[VM_RADIX_COUNT];      /* Child nodes. */
 101 };
 102
 103 static uma_zone_t vm_radix_node_zone;
 104
 105 /*
 106  * Allocate a radix node.  Pre-allocation should ensure that the request
 107  * will always be satisfied.
 108  */
 109 static __inline struct vm_radix_node *
 110 vm_radix_node_get(vm_pindex_t owner, uint16_t count, uint16_t clevel)
 111 {
 112         struct vm_radix_node *rnode;
 113
 114         rnode = uma_zalloc(vm_radix_node_zone, M_NOWAIT);
 115
 116         /*
 117          * The required number of nodes should already be pre-allocated
 118          * by vm_radix_prealloc().  However, UMA can hold a few nodes
 119          * in per-CPU buckets, which will not be accessible by the
 120          * current CPU.  Thus, the allocation could return NULL when
 121          * the pre-allocated pool is close to exhaustion.  Anyway,
 122          * in practice this should never occur because a new node
 123          * is not always required for insert.  Thus, the pre-allocated
 124          * pool should have some extra pages that prevent this from
 125          * becoming a problem.
 126          */
 127         if (rnode == NULL)
 128                 panic("%s: uma_zalloc() returned NULL for a new node",
 129                     __func__);
 130         rnode->rn_owner = owner;
 131         rnode->rn_count = count;
 132         rnode->rn_clev = clevel;
 133         return (rnode);
 134 }
 135
 136 /*
 137  * Free radix node.
 138  */
 139 static __inline void
 140 vm_radix_node_put(struct vm_radix_node *rnode)
 141 {
 142
 143         uma_zfree(vm_radix_node_zone, rnode);
 144 }
 145
 146 /*
 147  * Return the position in the array for a given level.
 148  */
 149 static __inline int
 150 vm_radix_slot(vm_pindex_t index, uint16_t level)
 151 {
 152
 153         return ((index >> ((VM_RADIX_LIMIT - level) * VM_RADIX_WIDTH)) &
 154             VM_RADIX_MASK);
 155 }
 156
 157 /* Trims the key after the specified level. */
 158 static __inline vm_pindex_t
 159 vm_radix_trimkey(vm_pindex_t index, uint16_t level)
 160 {
 161         vm_pindex_t ret;
 162
 163         ret = index;
 164         if (level < VM_RADIX_LIMIT) {
 165                 ret >>= (VM_RADIX_LIMIT - level) * VM_RADIX_WIDTH;
 166                 ret <<= (VM_RADIX_LIMIT - level) * VM_RADIX_WIDTH;
 167         }
 168         return (ret);
 169 }
 170
 171 /*
 172  * Get the root node for a radix tree.
 173  */
 174 static __inline struct vm_radix_node *
 175 vm_radix_getroot(struct vm_radix *rtree)
 176 {
 177
 178         return ((struct vm_radix_node *)rtree->rt_root);
 179 }
 180
 181 /*
 182  * Set the root node for a radix tree.
 183  */
 184 static __inline void
 185 vm_radix_setroot(struct vm_radix *rtree, struct vm_radix_node *rnode)
 186 {
 187
 188         rtree->rt_root = (uintptr_t)rnode;
 189 }
 190
 191 /*
 192  * Returns TRUE if the specified radix node is a leaf and FALSE otherwise.
 193  */
 194 static __inline boolean_t
 195 vm_radix_isleaf(struct vm_radix_node *rnode)
 196 {
 197
 198         return (((uintptr_t)rnode & VM_RADIX_ISLEAF) != 0);
 199 }
 200
 201 /*
 202  * Returns the associated page extracted from rnode.
 203  */
 204 static __inline vm_page_t
 205 vm_radix_topage(struct vm_radix_node *rnode)
 206 {
 207
 208         return ((vm_page_t)((uintptr_t)rnode & ~VM_RADIX_FLAGS));
 209 }
 210
 211 /*
 212  * Adds the page as a child of the provided node.
 213  */
 214 static __inline void
 215 vm_radix_addpage(struct vm_radix_node *rnode, vm_pindex_t index, uint16_t clev,
 216     vm_page_t page)
 217 {
 218         int slot;
 219
 220         slot = vm_radix_slot(index, clev);
 221         rnode->rn_child[slot] = (void *)((uintptr_t)page | VM_RADIX_ISLEAF);
 222 }
 223
 224 /*
 225  * Returns the slot where two keys differ.
 226  * It cannot accept 2 equal keys.
 227  */
 228 static __inline uint16_t
 229 vm_radix_keydiff(vm_pindex_t index1, vm_pindex_t index2)
 230 {
 231         uint16_t clev;
 232
 233         KASSERT(index1 != index2, ("%s: passing the same key value %jx",
 234             __func__, (uintmax_t)index1));
 235
 236         index1 ^= index2;
 237         for (clev = 0; clev <= VM_RADIX_LIMIT ; clev++)
 238                 if (vm_radix_slot(index1, clev))
 239                         return (clev);
 240         panic("%s: cannot reach this point", __func__);
 241         return (0);
 242 }
 243
 244 /*
 245  * Returns TRUE if it can be determined that key does not belong to the
 246  * specified rnode.  Otherwise, returns FALSE.
 247  */
 248 static __inline boolean_t
 249 vm_radix_keybarr(struct vm_radix_node *rnode, vm_pindex_t idx)
 250 {
 251
 252         if (rnode->rn_clev > 0) {
 253                 idx = vm_radix_trimkey(idx, rnode->rn_clev - 1);
 254                 return (idx != rnode->rn_owner);
 255         }
 256         return (FALSE);
 257 }
 258
 259 /*
 260  * Internal helper for vm_radix_reclaim_allnodes().
 261  * This function is recursive.
 262  */
 263 static void
 264 vm_radix_reclaim_allnodes_int(struct vm_radix_node *rnode)
 265 {
 266         int slot;
 267
 268         KASSERT(rnode->rn_count <= VM_RADIX_COUNT,
 269             ("vm_radix_reclaim_allnodes_int: bad count in rnode %p", rnode));
 270         for (slot = 0; rnode->rn_count != 0; slot++) {
 271                 if (rnode->rn_child[slot] == NULL)
 272                         continue;
 273                 if (!vm_radix_isleaf(rnode->rn_child[slot]))
 274                         vm_radix_reclaim_allnodes_int(rnode->rn_child[slot]);
 275                 rnode->rn_child[slot] = NULL;
 276                 rnode->rn_count--;
 277         }
 278         vm_radix_node_put(rnode);
 279 }
 280
 281 #ifdef INVARIANTS
 282 /*
 283  * Radix node zone destructor.
 284  */
 285 static void
 286 vm_radix_node_zone_dtor(void *mem, int size __unused, void *arg __unused)
 287 {
 288         struct vm_radix_node *rnode;
 289         int slot;
 290
 291         rnode = mem;
 292         KASSERT(rnode->rn_count == 0,
 293             ("vm_radix_node_put: rnode %p has %d children", rnode,
 294             rnode->rn_count));
 295         for (slot = 0; slot < VM_RADIX_COUNT; slot++)
 296                 KASSERT(rnode->rn_child[slot] == NULL,
 297                     ("vm_radix_node_put: rnode %p has a child", rnode));
 298 }
 299 #endif
 300
 301 /*
 302  * Radix node zone initializer.
 303  */
 304 static int
 305 vm_radix_node_zone_init(void *mem, int size __unused, int flags __unused)
 306 {
 307         struct vm_radix_node *rnode;
 308
 309         rnode = mem;
 310         memset(rnode->rn_child, 0, sizeof(rnode->rn_child));
 311         return (0);
 312 }
 313
 314 /*
 315  * Pre-allocate intermediate nodes from the UMA slab zone.
 316  */
 317 static void
 318 vm_radix_prealloc(void *arg __unused)
 319 {
 320         int nodes;
 321
 322         /*
 323          * Calculate the number of reserved nodes, discounting the pages that
 324          * are needed to store them.
 325          */
 326         nodes = ((vm_paddr_t)cnt.v_page_count * PAGE_SIZE) / (PAGE_SIZE +
 327             sizeof(struct vm_radix_node));
 328         if (!uma_zone_reserve_kva(vm_radix_node_zone, nodes))
 329                 panic("%s: unable to create new zone", __func__);
 330         uma_prealloc(vm_radix_node_zone, nodes);
 331 }
 332 SYSINIT(vm_radix_prealloc, SI_SUB_KMEM, SI_ORDER_SECOND, vm_radix_prealloc,
 333     NULL);
 334
 335 /*
 336  * Initialize the UMA slab zone.
 337  * Until vm_radix_prealloc() is called, the zone will be served by the
 338  * UMA boot-time pre-allocated pool of pages.
 339  */
 340 void
 341 vm_radix_init(void)
 342 {
 343
 344         vm_radix_node_zone = uma_zcreate("RADIX NODE",
 345             sizeof(struct vm_radix_node), NULL,
 346 #ifdef INVARIANTS
 347             vm_radix_node_zone_dtor,
 348 #else
 349             NULL,
 350 #endif
 351             vm_radix_node_zone_init, NULL, VM_RADIX_PAD, UMA_ZONE_VM |
 352             UMA_ZONE_NOFREE);
 353 }
 354
 355 /*
 356  * Inserts the key-value pair into the trie.
 357  * Panics if the key already exists.
 358  */
 359 void
 360 vm_radix_insert(struct vm_radix *rtree, vm_page_t page)
 361 {
 362         vm_pindex_t index, newind;
 363         void **parentp;
 364         struct vm_radix_node *rnode, *tmp;
 365         vm_page_t m;
 366         int slot;
 367         uint16_t clev;
 368
 369         index = page->pindex;
 370
 371         /*
 372          * The owner of record for root is not really important because it
 373          * will never be used.
 374          */
 375         rnode = vm_radix_getroot(rtree);
 376         if (rnode == NULL) {
 377                 rtree->rt_root = (uintptr_t)page | VM_RADIX_ISLEAF;
 378                 return;
 379         }
 380         parentp = (void **)&rtree->rt_root;
 381         for (;;) {
 382                 if (vm_radix_isleaf(rnode)) {
 383                         m = vm_radix_topage(rnode);
 384                         if (m->pindex == index)
 385                                 panic("%s: key %jx is already present",
 386                                     __func__, (uintmax_t)index);
 387                         clev = vm_radix_keydiff(m->pindex, index);
 388                         tmp = vm_radix_node_get(vm_radix_trimkey(index,
 389                             clev - 1), 2, clev);
 390                         *parentp = tmp;
 391                         vm_radix_addpage(tmp, index, clev, page);
 392                         vm_radix_addpage(tmp, m->pindex, clev, m);
 393                         return;
 394                 } else if (vm_radix_keybarr(rnode, index))
 395                         break;
 396                 slot = vm_radix_slot(index, rnode->rn_clev);
 397                 if (rnode->rn_child[slot] == NULL) {
 398                         rnode->rn_count++;
 399                         vm_radix_addpage(rnode, index, rnode->rn_clev, page);
 400                         return;
 401                 }
 402                 parentp = &rnode->rn_child[slot];
 403                 rnode = rnode->rn_child[slot];
 404         }
 405
 406         /*
 407          * A new node is needed because the right insertion level is reached.
 408          * Setup the new intermediate node and add the 2 children: the
 409          * new object and the older edge.
 410          */
 411         newind = rnode->rn_owner;
 412         clev = vm_radix_keydiff(newind, index);
 413         tmp = vm_radix_node_get(vm_radix_trimkey(index, clev - 1), 2,
 414             clev);
 415         *parentp = tmp;
 416         vm_radix_addpage(tmp, index, clev, page);
 417         slot = vm_radix_slot(newind, clev);
 418         tmp->rn_child[slot] = rnode;
 419 }
 420
 421 /*
 422  * Returns the value stored at the index.  If the index is not present,
 423  * NULL is returned.
 424  */
 425 vm_page_t
 426 vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
 427 {
 428         struct vm_radix_node *rnode;
 429         vm_page_t m;
 430         int slot;
 431
 432         rnode = vm_radix_getroot(rtree);
 433         while (rnode != NULL) {
 434                 if (vm_radix_isleaf(rnode)) {
 435                         m = vm_radix_topage(rnode);
 436                         if (m->pindex == index)
 437                                 return (m);
 438                         else
 439                                 break;
 440                 } else if (vm_radix_keybarr(rnode, index))
 441                         break;
 442                 slot = vm_radix_slot(index, rnode->rn_clev);
 443                 rnode = rnode->rn_child[slot];
 444         }
 445         return (NULL);
 446 }
 447
 448 /*
 449  * Look up the nearest entry at a position bigger than or equal to index.
 450  */
 451 vm_page_t
 452 vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
 453 {
 454         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 455         vm_pindex_t inc;
 456         vm_page_t m;
 457         struct vm_radix_node *child, *rnode;
 458 #ifdef INVARIANTS
 459         int loops = 0;
 460 #endif
 461         int slot, tos;
 462
 463         rnode = vm_radix_getroot(rtree);
 464         if (rnode == NULL)
 465                 return (NULL);
 466         else if (vm_radix_isleaf(rnode)) {
 467                 m = vm_radix_topage(rnode);
 468                 if (m->pindex >= index)
 469                         return (m);
 470                 else
 471                         return (NULL);
 472         }
 473         tos = 0;
 474         for (;;) {
 475                 /*
 476                  * If the keys differ before the current bisection node,
 477                  * then the search key might rollback to the earliest
 478                  * available bisection node or to the smallest key
 479                  * in the current node (if the owner is bigger than the
 480                  * search key).
 481                  */
 482                 if (vm_radix_keybarr(rnode, index)) {
 483                         if (index > rnode->rn_owner) {
 484 ascend:
 485                                 KASSERT(++loops < 1000,
 486                                     ("vm_radix_lookup_ge: too many loops"));
 487
 488                                 /*
 489                                  * Pop nodes from the stack until either the
 490                                  * stack is empty or a node that could have a
 491                                  * matching descendant is found.
 492                                  */
 493                                 do {
 494                                         if (tos == 0)
 495                                                 return (NULL);
 496                                         rnode = stack[--tos];
 497                                 } while (vm_radix_slot(index,
 498                                     rnode->rn_clev) == (VM_RADIX_COUNT - 1));
 499
 500                                 /*
 501                                  * The following computation cannot overflow
 502                                  * because index's slot at the current level
 503                                  * is less than VM_RADIX_COUNT - 1.
 504                                  */
 505                                 index = vm_radix_trimkey(index,
 506                                     rnode->rn_clev);
 507                                 index += VM_RADIX_UNITLEVEL(rnode->rn_clev);
 508                         } else
 509                                 index = rnode->rn_owner;
 510                         KASSERT(!vm_radix_keybarr(rnode, index),
 511                             ("vm_radix_lookup_ge: keybarr failed"));
 512                 }
 513                 slot = vm_radix_slot(index, rnode->rn_clev);
 514                 child = rnode->rn_child[slot];
 515                 if (vm_radix_isleaf(child)) {
 516                         m = vm_radix_topage(child);
 517                         if (m->pindex >= index)
 518                                 return (m);
 519                 } else if (child != NULL)
 520                         goto descend;
 521
 522                 /*
 523                  * Look for an available edge or page within the current
 524                  * bisection node.
 525                  */
 526                 if (slot < (VM_RADIX_COUNT - 1)) {
 527                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 528                         index = vm_radix_trimkey(index, rnode->rn_clev);
 529                         do {
 530                                 index += inc;
 531                                 slot++;
 532                                 child = rnode->rn_child[slot];
 533                                 if (vm_radix_isleaf(child)) {
 534                                         m = vm_radix_topage(child);
 535                                         if (m->pindex >= index)
 536                                                 return (m);
 537                                 } else if (child != NULL)
 538                                         goto descend;
 539                         } while (slot < (VM_RADIX_COUNT - 1));
 540                 }
 541                 KASSERT(child == NULL || vm_radix_isleaf(child),
 542                     ("vm_radix_lookup_ge: child is radix node"));
 543
 544                 /*
 545                  * If a page or edge bigger than the search slot is not found
 546                  * in the current node, ascend to the next higher-level node.
 547                  */
 548                 goto ascend;
 549 descend:
 550                 KASSERT(rnode->rn_clev < VM_RADIX_LIMIT,
 551                     ("vm_radix_lookup_ge: pushing leaf's parent"));
 552                 KASSERT(tos < VM_RADIX_LIMIT,
 553                     ("vm_radix_lookup_ge: stack overflow"));
 554                 stack[tos++] = rnode;
 555                 rnode = child;
 556         }
 557 }
 558
 559 /*
 560  * Look up the nearest entry at a position less than or equal to index.
 561  */
 562 vm_page_t
 563 vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
 564 {
 565         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 566         vm_pindex_t inc;
 567         vm_page_t m;
 568         struct vm_radix_node *child, *rnode;
 569 #ifdef INVARIANTS
 570         int loops = 0;
 571 #endif
 572         int slot, tos;
 573
 574         rnode = vm_radix_getroot(rtree);
 575         if (rnode == NULL)
 576                 return (NULL);
 577         else if (vm_radix_isleaf(rnode)) {
 578                 m = vm_radix_topage(rnode);
 579                 if (m->pindex <= index)
 580                         return (m);
 581                 else
 582                         return (NULL);
 583         }
 584         tos = 0;
 585         for (;;) {
 586                 /*
 587                  * If the keys differ before the current bisection node,
 588                  * then the search key might rollback to the earliest
 589                  * available bisection node or to the largest key
 590                  * in the current node (if the owner is smaller than the
 591                  * search key).
 592                  */
 593                 if (vm_radix_keybarr(rnode, index)) {
 594                         if (index > rnode->rn_owner) {
 595                                 index = rnode->rn_owner + VM_RADIX_COUNT *
 596                                     VM_RADIX_UNITLEVEL(rnode->rn_clev);
 597                         } else {
 598 ascend:
 599                                 KASSERT(++loops < 1000,
 600                                     ("vm_radix_lookup_le: too many loops"));
 601
 602                                 /*
 603                                  * Pop nodes from the stack until either the
 604                                  * stack is empty or a node that could have a
 605                                  * matching descendant is found.
 606                                  */
 607                                 do {
 608                                         if (tos == 0)
 609                                                 return (NULL);
 610                                         rnode = stack[--tos];
 611                                 } while (vm_radix_slot(index,
 612                                     rnode->rn_clev) == 0);
 613
 614                                 /*
 615                                  * The following computation cannot overflow
 616                                  * because index's slot at the current level
 617                                  * is greater than 0.
 618                                  */
 619                                 index = vm_radix_trimkey(index,
 620                                     rnode->rn_clev);
 621                         }
 622                         index--;
 623                         KASSERT(!vm_radix_keybarr(rnode, index),
 624                             ("vm_radix_lookup_le: keybarr failed"));
 625                 }
 626                 slot = vm_radix_slot(index, rnode->rn_clev);
 627                 child = rnode->rn_child[slot];
 628                 if (vm_radix_isleaf(child)) {
 629                         m = vm_radix_topage(child);
 630                         if (m->pindex <= index)
 631                                 return (m);
 632                 } else if (child != NULL)
 633                         goto descend;
 634
 635                 /*
 636                  * Look for an available edge or page within the current
 637                  * bisection node.
 638                  */
 639                 if (slot > 0) {
 640                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 641                         index |= inc - 1;
 642                         do {
 643                                 index -= inc;
 644                                 slot--;
 645                                 child = rnode->rn_child[slot];
 646                                 if (vm_radix_isleaf(child)) {
 647                                         m = vm_radix_topage(child);
 648                                         if (m->pindex <= index)
 649                                                 return (m);
 650                                 } else if (child != NULL)
 651                                         goto descend;
 652                         } while (slot > 0);
 653                 }
 654                 KASSERT(child == NULL || vm_radix_isleaf(child),
 655                     ("vm_radix_lookup_le: child is radix node"));
 656
 657                 /*
 658                  * If a page or edge smaller than the search slot is not found
 659                  * in the current node, ascend to the next higher-level node.
 660                  */
 661                 goto ascend;
 662 descend:
 663                 KASSERT(rnode->rn_clev < VM_RADIX_LIMIT,
 664                     ("vm_radix_lookup_le: pushing leaf's parent"));
 665                 KASSERT(tos < VM_RADIX_LIMIT,
 666                     ("vm_radix_lookup_le: stack overflow"));
 667                 stack[tos++] = rnode;
 668                 rnode = child;
 669         }
 670 }
 671
 672 /*
 673  * Remove the specified index from the tree.
 674  * Panics if the key is not present.
 675  */
 676 void
 677 vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index)
 678 {
 679         struct vm_radix_node *rnode, *parent;
 680         vm_page_t m;
 681         int i, slot;
 682
 683         rnode = vm_radix_getroot(rtree);
 684         if (vm_radix_isleaf(rnode)) {
 685                 m = vm_radix_topage(rnode);
 686                 if (m->pindex != index)
 687                         panic("%s: invalid key found", __func__);
 688                 vm_radix_setroot(rtree, NULL);
 689                 return;
 690         }
 691         parent = NULL;
 692         for (;;) {
 693                 if (rnode == NULL)
 694                         panic("vm_radix_remove: impossible to locate the key");
 695                 slot = vm_radix_slot(index, rnode->rn_clev);
 696                 if (vm_radix_isleaf(rnode->rn_child[slot])) {
 697                         m = vm_radix_topage(rnode->rn_child[slot]);
 698                         if (m->pindex != index)
 699                                 panic("%s: invalid key found", __func__);
 700                         rnode->rn_child[slot] = NULL;
 701                         rnode->rn_count--;
 702                         if (rnode->rn_count > 1)
 703                                 break;
 704                         for (i = 0; i < VM_RADIX_COUNT; i++)
 705                                 if (rnode->rn_child[i] != NULL)
 706                                         break;
 707                         KASSERT(i != VM_RADIX_COUNT,
 708                             ("%s: invalid node configuration", __func__));
 709                         if (parent == NULL)
 710                                 vm_radix_setroot(rtree, rnode->rn_child[i]);
 711                         else {
 712                                 slot = vm_radix_slot(index, parent->rn_clev);
 713                                 KASSERT(parent->rn_child[slot] == rnode,
 714                                     ("%s: invalid child value", __func__));
 715                                 parent->rn_child[slot] = rnode->rn_child[i];
 716                         }
 717                         rnode->rn_count--;
 718                         rnode->rn_child[i] = NULL;
 719                         vm_radix_node_put(rnode);
 720                         break;
 721                 }
 722                 parent = rnode;
 723                 rnode = rnode->rn_child[slot];
 724         }
 725 }
 726
 727 /*
 728  * Remove and free all the nodes from the radix tree.
 729  * This function is recursive but there is a tight control on it as the
 730  * maximum depth of the tree is fixed.
 731  */
 732 void
 733 vm_radix_reclaim_allnodes(struct vm_radix *rtree)
 734 {
 735         struct vm_radix_node *root;
 736
 737         root = vm_radix_getroot(rtree);
 738         if (root == NULL)
 739                 return;
 740         vm_radix_setroot(rtree, NULL);
 741         if (!vm_radix_isleaf(root))
 742                 vm_radix_reclaim_allnodes_int(root);
 743 }
 744
 745 #ifdef DDB
 746 /*
 747  * Show details about the given radix node.
 748  */
 749 DB_SHOW_COMMAND(radixnode, db_show_radixnode)
 750 {
 751         struct vm_radix_node *rnode;
 752         int i;
 753
 754         if (!have_addr)
 755                 return;
 756         rnode = (struct vm_radix_node *)addr;
 757         db_printf("radixnode %p, owner %jx, children count %u, level %u:\n",
 758             (void *)rnode, (uintmax_t)rnode->rn_owner, rnode->rn_count,
 759             rnode->rn_clev);
 760         for (i = 0; i < VM_RADIX_COUNT; i++)
 761                 if (rnode->rn_child[i] != NULL)
 762                         db_printf("slot: %d, val: %p, page: %p, clev: %d\n",
 763                             i, (void *)rnode->rn_child[i],
 764                             vm_radix_isleaf(rnode->rn_child[i]) ?
 765                             vm_radix_topage(rnode->rn_child[i]) : NULL,
 766                             rnode->rn_clev);
 767 }
 768 #endif /* DDB */