2 * KERN_SLABALLOC.C - Kernel SLAB memory allocator (MP SAFE)
4 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
6 * This code is derived from software contributed to The DragonFly Project
7 * by Matthew Dillon <dillon@backplane.com>
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
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23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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36 * $DragonFly: src/sys/kern/kern_slaballoc.c,v 1.31 2005/04/26 00:47:59 dillon Exp $
38 * This module implements a slab allocator drop-in replacement for the
41 * A slab allocator reserves a ZONE for each chunk size, then lays the
42 * chunks out in an array within the zone. Allocation and deallocation
43 * is nearly instantanious, and fragmentation/overhead losses are limited
44 * to a fixed worst-case amount.
46 * The downside of this slab implementation is in the chunk size
47 * multiplied by the number of zones. ~80 zones * 128K = 10MB of VM per cpu.
48 * In a kernel implementation all this memory will be physical so
49 * the zone size is adjusted downward on machines with less physical
50 * memory. The upside is that overhead is bounded... this is the *worst*
53 * Slab management is done on a per-cpu basis and no locking or mutexes
54 * are required, only a critical section. When one cpu frees memory
55 * belonging to another cpu's slab manager an asynchronous IPI message
56 * will be queued to execute the operation. In addition, both the
57 * high level slab allocator and the low level zone allocator optimize
58 * M_ZERO requests, and the slab allocator does not have to pre initialize
59 * the linked list of chunks.
61 * XXX Balancing is needed between cpus. Balance will be handled through
62 * asynchronous IPIs primarily by reassigning the z_Cpu ownership of chunks.
64 * XXX If we have to allocate a new zone and M_USE_RESERVE is set, use of
65 * the new zone should be restricted to M_USE_RESERVE requests only.
67 * Alloc Size Chunking Number of zones
77 * (if PAGE_SIZE is 4K the maximum zone allocation is 16383)
79 * Allocations >= ZoneLimit go directly to kmem.
81 * API REQUIREMENTS AND SIDE EFFECTS
83 * To operate as a drop-in replacement to the FreeBSD-4.x malloc() we
84 * have remained compatible with the following API requirements:
86 * + small power-of-2 sized allocations are power-of-2 aligned (kern_tty)
87 * + all power-of-2 sized allocations are power-of-2 aligned (twe)
88 * + malloc(0) is allowed and returns non-NULL (ahc driver)
89 * + ability to allocate arbitrarily large chunks of memory
94 #include <sys/param.h>
95 #include <sys/systm.h>
96 #include <sys/kernel.h>
97 #include <sys/slaballoc.h>
99 #include <sys/vmmeter.h>
100 #include <sys/lock.h>
101 #include <sys/thread.h>
102 #include <sys/globaldata.h>
105 #include <vm/vm_param.h>
106 #include <vm/vm_kern.h>
107 #include <vm/vm_extern.h>
108 #include <vm/vm_object.h>
110 #include <vm/vm_map.h>
111 #include <vm/vm_page.h>
112 #include <vm/vm_pageout.h>
114 #include <machine/cpu.h>
116 #include <sys/thread2.h>
118 #define arysize(ary) (sizeof(ary)/sizeof((ary)[0]))
121 * Fixed globals (not per-cpu)
124 static int ZoneLimit;
125 static int ZonePageCount;
127 static struct malloc_type *kmemstatistics;
128 static struct kmemusage *kmemusage;
129 static int32_t weirdary[16];
131 static void *kmem_slab_alloc(vm_size_t bytes, vm_offset_t align, int flags);
132 static void kmem_slab_free(void *ptr, vm_size_t bytes);
135 * Misc constants. Note that allocations that are exact multiples of
136 * PAGE_SIZE, or exceed the zone limit, fall through to the kmem module.
137 * IN_SAME_PAGE_MASK is used to sanity-check the per-page free lists.
139 #define MIN_CHUNK_SIZE 8 /* in bytes */
140 #define MIN_CHUNK_MASK (MIN_CHUNK_SIZE - 1)
141 #define ZONE_RELS_THRESH 2 /* threshold number of zones */
142 #define IN_SAME_PAGE_MASK (~(intptr_t)PAGE_MASK | MIN_CHUNK_MASK)
145 * The WEIRD_ADDR is used as known text to copy into free objects to
146 * try to create deterministic failure cases if the data is accessed after
149 #define WEIRD_ADDR 0xdeadc0de
150 #define MAX_COPY sizeof(weirdary)
151 #define ZERO_LENGTH_PTR ((void *)-8)
154 * Misc global malloc buckets
157 MALLOC_DEFINE(M_CACHE, "cache", "Various Dynamically allocated caches");
158 MALLOC_DEFINE(M_DEVBUF, "devbuf", "device driver memory");
159 MALLOC_DEFINE(M_TEMP, "temp", "misc temporary data buffers");
161 MALLOC_DEFINE(M_IP6OPT, "ip6opt", "IPv6 options");
162 MALLOC_DEFINE(M_IP6NDP, "ip6ndp", "IPv6 Neighbor Discovery");
165 * Initialize the slab memory allocator. We have to choose a zone size based
166 * on available physical memory. We choose a zone side which is approximately
167 * 1/1024th of our memory, so if we have 128MB of ram we have a zone size of
168 * 128K. The zone size is limited to the bounds set in slaballoc.h
169 * (typically 32K min, 128K max).
171 static void kmeminit(void *dummy);
173 SYSINIT(kmem, SI_SUB_KMEM, SI_ORDER_FIRST, kmeminit, NULL)
176 kmeminit(void *dummy)
183 limsize = (vm_poff_t)vmstats.v_page_count * PAGE_SIZE;
184 if (limsize > VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS)
185 limsize = VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS;
187 usesize = (int)(limsize / 1024); /* convert to KB */
189 ZoneSize = ZALLOC_MIN_ZONE_SIZE;
190 while (ZoneSize < ZALLOC_MAX_ZONE_SIZE && (ZoneSize << 1) < usesize)
192 ZoneLimit = ZoneSize / 4;
193 if (ZoneLimit > ZALLOC_ZONE_LIMIT)
194 ZoneLimit = ZALLOC_ZONE_LIMIT;
195 ZoneMask = ZoneSize - 1;
196 ZonePageCount = ZoneSize / PAGE_SIZE;
198 npg = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE;
199 kmemusage = kmem_slab_alloc(npg * sizeof(struct kmemusage), PAGE_SIZE, M_WAITOK|M_ZERO);
201 for (i = 0; i < arysize(weirdary); ++i)
202 weirdary[i] = WEIRD_ADDR;
205 printf("Slab ZoneSize set to %dKB\n", ZoneSize / 1024);
209 * Initialize a malloc type tracking structure.
212 malloc_init(void *data)
214 struct malloc_type *type = data;
217 if (type->ks_magic != M_MAGIC)
218 panic("malloc type lacks magic");
220 if (type->ks_limit != 0)
223 if (vmstats.v_page_count == 0)
224 panic("malloc_init not allowed before vm init");
226 limsize = (vm_poff_t)vmstats.v_page_count * PAGE_SIZE;
227 if (limsize > VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS)
228 limsize = VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS;
229 type->ks_limit = limsize / 10;
231 type->ks_next = kmemstatistics;
232 kmemstatistics = type;
236 malloc_uninit(void *data)
238 struct malloc_type *type = data;
239 struct malloc_type *t;
245 if (type->ks_magic != M_MAGIC)
246 panic("malloc type lacks magic");
248 if (vmstats.v_page_count == 0)
249 panic("malloc_uninit not allowed before vm init");
251 if (type->ks_limit == 0)
252 panic("malloc_uninit on uninitialized type");
256 * memuse is only correct in aggregation. Due to memory being allocated
257 * on one cpu and freed on another individual array entries may be
258 * negative or positive (canceling each other out).
260 for (i = ttl = 0; i < ncpus; ++i)
261 ttl += type->ks_memuse[i];
263 printf("malloc_uninit: %ld bytes of '%s' still allocated on cpu %d\n",
264 ttl, type->ks_shortdesc, i);
267 if (type == kmemstatistics) {
268 kmemstatistics = type->ks_next;
270 for (t = kmemstatistics; t->ks_next != NULL; t = t->ks_next) {
271 if (t->ks_next == type) {
272 t->ks_next = type->ks_next;
277 type->ks_next = NULL;
282 * Calculate the zone index for the allocation request size and set the
283 * allocation request size to that particular zone's chunk size.
286 zoneindex(unsigned long *bytes)
288 unsigned int n = (unsigned int)*bytes; /* unsigned for shift opt */
290 *bytes = n = (n + 7) & ~7;
291 return(n / 8 - 1); /* 8 byte chunks, 16 zones */
294 *bytes = n = (n + 15) & ~15;
299 *bytes = n = (n + 31) & ~31;
303 *bytes = n = (n + 63) & ~63;
307 *bytes = n = (n + 127) & ~127;
308 return(n / 128 + 31);
311 *bytes = n = (n + 255) & ~255;
312 return(n / 256 + 39);
314 *bytes = n = (n + 511) & ~511;
315 return(n / 512 + 47);
317 #if ZALLOC_ZONE_LIMIT > 8192
319 *bytes = n = (n + 1023) & ~1023;
320 return(n / 1024 + 55);
323 #if ZALLOC_ZONE_LIMIT > 16384
325 *bytes = n = (n + 2047) & ~2047;
326 return(n / 2048 + 63);
329 panic("Unexpected byte count %d", n);
334 * malloc() (SLAB ALLOCATOR) (MP SAFE)
336 * Allocate memory via the slab allocator. If the request is too large,
337 * or if it page-aligned beyond a certain size, we fall back to the
338 * KMEM subsystem. A SLAB tracking descriptor must be specified, use
339 * &SlabMisc if you don't care.
341 * M_RNOWAIT - don't block.
342 * M_NULLOK - return NULL instead of blocking.
343 * M_ZERO - zero the returned memory.
344 * M_USE_RESERVE - allow greater drawdown of the free list
345 * M_USE_INTERRUPT_RESERVE - allow the freelist to be exhausted
348 malloc(unsigned long size, struct malloc_type *type, int flags)
353 struct globaldata *gd;
360 * XXX silly to have this in the critical path.
362 if (type->ks_limit == 0) {
364 if (type->ks_limit == 0)
371 * Handle the case where the limit is reached. Panic if we can't return
372 * NULL. The original malloc code looped, but this tended to
373 * simply deadlock the computer.
375 * ks_loosememuse is an up-only limit that is NOT MP-synchronized, used
376 * to determine if a more complete limit check should be done. The
377 * actual memory use is tracked via ks_memuse[cpu].
379 while (type->ks_loosememuse >= type->ks_limit) {
383 for (i = ttl = 0; i < ncpus; ++i)
384 ttl += type->ks_memuse[i];
385 type->ks_loosememuse = ttl; /* not MP synchronized */
386 if (ttl >= type->ks_limit) {
387 if (flags & M_NULLOK)
389 panic("%s: malloc limit exceeded", type->ks_shortdesc);
394 * Handle the degenerate size == 0 case. Yes, this does happen.
395 * Return a special pointer. This is to maintain compatibility with
396 * the original malloc implementation. Certain devices, such as the
397 * adaptec driver, not only allocate 0 bytes, they check for NULL and
398 * also realloc() later on. Joy.
401 return(ZERO_LENGTH_PTR);
404 * Handle hysteresis from prior frees here in malloc(). We cannot
405 * safely manipulate the kernel_map in free() due to free() possibly
406 * being called via an IPI message or from sensitive interrupt code.
408 while (slgd->NFreeZones > ZONE_RELS_THRESH && (flags & M_RNOWAIT) == 0) {
410 if (slgd->NFreeZones > ZONE_RELS_THRESH) { /* crit sect race */
412 slgd->FreeZones = z->z_Next;
414 kmem_slab_free(z, ZoneSize); /* may block */
419 * XXX handle oversized frees that were queued from free().
421 while (slgd->FreeOvZones && (flags & M_RNOWAIT) == 0) {
423 if ((z = slgd->FreeOvZones) != NULL) {
424 KKASSERT(z->z_Magic == ZALLOC_OVSZ_MAGIC);
425 slgd->FreeOvZones = z->z_Next;
426 kmem_slab_free(z, z->z_ChunkSize); /* may block */
432 * Handle large allocations directly. There should not be very many of
433 * these so performance is not a big issue.
435 * Guarentee page alignment for allocations in multiples of PAGE_SIZE
437 if (size >= ZoneLimit || (size & PAGE_MASK) == 0) {
438 struct kmemusage *kup;
440 size = round_page(size);
441 chunk = kmem_slab_alloc(size, PAGE_SIZE, flags);
444 flags &= ~M_ZERO; /* result already zero'd if M_ZERO was set */
445 flags |= M_PASSIVE_ZERO;
447 kup->ku_pagecnt = size / PAGE_SIZE;
448 kup->ku_cpu = gd->gd_cpuid;
454 * Attempt to allocate out of an existing zone. First try the free list,
455 * then allocate out of unallocated space. If we find a good zone move
456 * it to the head of the list so later allocations find it quickly
457 * (we might have thousands of zones in the list).
459 * Note: zoneindex() will panic of size is too large.
461 zi = zoneindex(&size);
462 KKASSERT(zi < NZONES);
464 if ((z = slgd->ZoneAry[zi]) != NULL) {
465 KKASSERT(z->z_NFree > 0);
468 * Remove us from the ZoneAry[] when we become empty
470 if (--z->z_NFree == 0) {
471 slgd->ZoneAry[zi] = z->z_Next;
476 * Locate a chunk in a free page. This attempts to localize
477 * reallocations into earlier pages without us having to sort
478 * the chunk list. A chunk may still overlap a page boundary.
480 while (z->z_FirstFreePg < ZonePageCount) {
481 if ((chunk = z->z_PageAry[z->z_FirstFreePg]) != NULL) {
484 * Diagnostic: c_Next is not total garbage.
486 KKASSERT(chunk->c_Next == NULL ||
487 ((intptr_t)chunk->c_Next & IN_SAME_PAGE_MASK) ==
488 ((intptr_t)chunk & IN_SAME_PAGE_MASK));
491 if ((uintptr_t)chunk < VM_MIN_KERNEL_ADDRESS)
492 panic("chunk %p FFPG %d/%d", chunk, z->z_FirstFreePg, ZonePageCount);
493 if (chunk->c_Next && (uintptr_t)chunk->c_Next < VM_MIN_KERNEL_ADDRESS)
494 panic("chunkNEXT %p %p FFPG %d/%d", chunk, chunk->c_Next, z->z_FirstFreePg, ZonePageCount);
496 z->z_PageAry[z->z_FirstFreePg] = chunk->c_Next;
503 * No chunks are available but NFree said we had some memory, so
504 * it must be available in the never-before-used-memory area
505 * governed by UIndex. The consequences are very serious if our zone
506 * got corrupted so we use an explicit panic rather then a KASSERT.
508 if (z->z_UIndex + 1 != z->z_NMax)
509 z->z_UIndex = z->z_UIndex + 1;
512 if (z->z_UIndex == z->z_UEndIndex)
513 panic("slaballoc: corrupted zone");
514 chunk = (SLChunk *)(z->z_BasePtr + z->z_UIndex * size);
515 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) {
517 flags |= M_PASSIVE_ZERO;
523 * If all zones are exhausted we need to allocate a new zone for this
524 * index. Use M_ZERO to take advantage of pre-zerod pages. Also see
525 * UAlloc use above in regards to M_ZERO. Note that when we are reusing
526 * a zone from the FreeZones list UAlloc'd data will not be zero'd, and
527 * we do not pre-zero it because we do not want to mess up the L1 cache.
529 * At least one subsystem, the tty code (see CROUND) expects power-of-2
530 * allocations to be power-of-2 aligned. We maintain compatibility by
531 * adjusting the base offset below.
536 if ((z = slgd->FreeZones) != NULL) {
537 slgd->FreeZones = z->z_Next;
539 bzero(z, sizeof(SLZone));
540 z->z_Flags |= SLZF_UNOTZEROD;
542 z = kmem_slab_alloc(ZoneSize, ZoneSize, flags|M_ZERO);
548 * Guarentee power-of-2 alignment for power-of-2-sized chunks.
549 * Otherwise just 8-byte align the data.
551 if ((size | (size - 1)) + 1 == (size << 1))
552 off = (sizeof(SLZone) + size - 1) & ~(size - 1);
554 off = (sizeof(SLZone) + MIN_CHUNK_MASK) & ~MIN_CHUNK_MASK;
555 z->z_Magic = ZALLOC_SLAB_MAGIC;
557 z->z_NMax = (ZoneSize - off) / size;
558 z->z_NFree = z->z_NMax - 1;
559 z->z_BasePtr = (char *)z + off;
560 z->z_UIndex = z->z_UEndIndex = slgd->JunkIndex % z->z_NMax;
561 z->z_ChunkSize = size;
562 z->z_FirstFreePg = ZonePageCount;
564 z->z_Cpu = gd->gd_cpuid;
565 chunk = (SLChunk *)(z->z_BasePtr + z->z_UIndex * size);
566 z->z_Next = slgd->ZoneAry[zi];
567 slgd->ZoneAry[zi] = z;
568 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) {
569 flags &= ~M_ZERO; /* already zero'd */
570 flags |= M_PASSIVE_ZERO;
574 * Slide the base index for initial allocations out of the next
575 * zone we create so we do not over-weight the lower part of the
578 slgd->JunkIndex = (slgd->JunkIndex + ZALLOC_SLAB_SLIDE)
579 & (ZALLOC_MAX_ZONE_SIZE - 1);
582 ++type->ks_inuse[gd->gd_cpuid];
583 type->ks_memuse[gd->gd_cpuid] += size;
584 type->ks_loosememuse += size; /* not MP synchronized */
589 else if ((flags & (M_ZERO|M_PASSIVE_ZERO)) == 0)
590 chunk->c_Next = (void *)-1; /* avoid accidental double-free check */
599 * kernel realloc. (SLAB ALLOCATOR) (MP SAFE)
601 * Generally speaking this routine is not called very often and we do
602 * not attempt to optimize it beyond reusing the same pointer if the
603 * new size fits within the chunking of the old pointer's zone.
606 realloc(void *ptr, unsigned long size, struct malloc_type *type, int flags)
612 KKASSERT((flags & M_ZERO) == 0); /* not supported */
614 if (ptr == NULL || ptr == ZERO_LENGTH_PTR)
615 return(malloc(size, type, flags));
622 * Handle oversized allocations. XXX we really should require that a
623 * size be passed to free() instead of this nonsense.
626 struct kmemusage *kup;
629 if (kup->ku_pagecnt) {
630 osize = kup->ku_pagecnt << PAGE_SHIFT;
631 if (osize == round_page(size))
633 if ((nptr = malloc(size, type, flags)) == NULL)
635 bcopy(ptr, nptr, min(size, osize));
642 * Get the original allocation's zone. If the new request winds up
643 * using the same chunk size we do not have to do anything.
645 z = (SLZone *)((uintptr_t)ptr & ~(uintptr_t)ZoneMask);
646 KKASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC);
649 if (z->z_ChunkSize == size)
653 * Allocate memory for the new request size. Note that zoneindex has
654 * already adjusted the request size to the appropriate chunk size, which
655 * should optimize our bcopy(). Then copy and return the new pointer.
657 if ((nptr = malloc(size, type, flags)) == NULL)
659 bcopy(ptr, nptr, min(size, z->z_ChunkSize));
665 * Allocate a copy of the specified string.
667 * (MP SAFE) (MAY BLOCK)
670 strdup(const char *str, struct malloc_type *type)
672 int zlen; /* length inclusive of terminating NUL */
677 zlen = strlen(str) + 1;
678 nstr = malloc(zlen, type, M_WAITOK);
679 bcopy(str, nstr, zlen);
685 * free() (SLAB ALLOCATOR)
687 * Free the specified chunk of memory.
691 free_remote(void *ptr)
693 free(ptr, *(struct malloc_type **)ptr);
699 * free (SLAB ALLOCATOR) (MP SAFE)
701 * Free a memory block previously allocated by malloc. Note that we do not
702 * attempt to uplodate ks_loosememuse as MP races could prevent us from
703 * checking memory limits in malloc.
706 free(void *ptr, struct malloc_type *type)
711 struct globaldata *gd;
718 panic("trying to free NULL pointer");
721 * Handle special 0-byte allocations
723 if (ptr == ZERO_LENGTH_PTR)
727 * Handle oversized allocations. XXX we really should require that a
728 * size be passed to free() instead of this nonsense.
730 * This code is never called via an ipi.
733 struct kmemusage *kup;
737 if (kup->ku_pagecnt) {
738 size = kup->ku_pagecnt << PAGE_SHIFT;
741 KKASSERT(sizeof(weirdary) <= size);
742 bcopy(weirdary, ptr, sizeof(weirdary));
745 * note: we always adjust our cpu's slot, not the originating
746 * cpu (kup->ku_cpuid). The statistics are in aggregate.
748 * note: XXX we have still inherited the interrupts-can't-block
749 * assumption. An interrupt thread does not bump
750 * gd_intr_nesting_level so check TDF_INTTHREAD. This is
751 * primarily until we can fix softupdate's assumptions about free().
754 --type->ks_inuse[gd->gd_cpuid];
755 type->ks_memuse[gd->gd_cpuid] -= size;
756 if (mycpu->gd_intr_nesting_level || (gd->gd_curthread->td_flags & TDF_INTTHREAD)) {
758 z->z_Magic = ZALLOC_OVSZ_MAGIC;
759 z->z_Next = slgd->FreeOvZones;
760 z->z_ChunkSize = size;
761 slgd->FreeOvZones = z;
765 kmem_slab_free(ptr, size); /* may block */
772 * Zone case. Figure out the zone based on the fact that it is
775 z = (SLZone *)((uintptr_t)ptr & ~(uintptr_t)ZoneMask);
776 KKASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC);
779 * If we do not own the zone then forward the request to the
780 * cpu that does. Since the timing is non-critical, a passive
783 if (z->z_CpuGd != gd) {
784 *(struct malloc_type **)ptr = type;
786 lwkt_send_ipiq_passive(z->z_CpuGd, free_remote, ptr);
788 panic("Corrupt SLZone");
793 if (type->ks_magic != M_MAGIC)
794 panic("free: malloc type lacks magic");
797 pgno = ((char *)ptr - (char *)z) >> PAGE_SHIFT;
802 * Attempt to detect a double-free. To reduce overhead we only check
803 * if there appears to be link pointer at the base of the data.
805 if (((intptr_t)chunk->c_Next - (intptr_t)z) >> PAGE_SHIFT == pgno) {
807 for (scan = z->z_PageAry[pgno]; scan; scan = scan->c_Next) {
809 panic("Double free at %p", chunk);
815 * Put weird data into the memory to detect modifications after freeing,
816 * illegal pointer use after freeing (we should fault on the odd address),
817 * and so forth. XXX needs more work, see the old malloc code.
820 if (z->z_ChunkSize < sizeof(weirdary))
821 bcopy(weirdary, chunk, z->z_ChunkSize);
823 bcopy(weirdary, chunk, sizeof(weirdary));
827 * Add this free non-zero'd chunk to a linked list for reuse, adjust
831 if ((uintptr_t)chunk < VM_MIN_KERNEL_ADDRESS)
832 panic("BADFREE %p", chunk);
834 chunk->c_Next = z->z_PageAry[pgno];
835 z->z_PageAry[pgno] = chunk;
837 if (chunk->c_Next && (uintptr_t)chunk->c_Next < VM_MIN_KERNEL_ADDRESS)
840 if (z->z_FirstFreePg > pgno)
841 z->z_FirstFreePg = pgno;
844 * Bump the number of free chunks. If it becomes non-zero the zone
845 * must be added back onto the appropriate list.
847 if (z->z_NFree++ == 0) {
848 z->z_Next = slgd->ZoneAry[z->z_ZoneIndex];
849 slgd->ZoneAry[z->z_ZoneIndex] = z;
852 --type->ks_inuse[z->z_Cpu];
853 type->ks_memuse[z->z_Cpu] -= z->z_ChunkSize;
856 * If the zone becomes totally free, and there are other zones we
857 * can allocate from, move this zone to the FreeZones list. Since
858 * this code can be called from an IPI callback, do *NOT* try to mess
859 * with kernel_map here. Hysteresis will be performed at malloc() time.
861 if (z->z_NFree == z->z_NMax &&
862 (z->z_Next || slgd->ZoneAry[z->z_ZoneIndex] != z)
866 for (pz = &slgd->ZoneAry[z->z_ZoneIndex]; z != *pz; pz = &(*pz)->z_Next)
870 z->z_Next = slgd->FreeZones;
878 * kmem_slab_alloc() (MP SAFE) (GETS BGL)
880 * Directly allocate and wire kernel memory in PAGE_SIZE chunks with the
881 * specified alignment. M_* flags are expected in the flags field.
883 * Alignment must be a multiple of PAGE_SIZE.
885 * NOTE! XXX For the moment we use vm_map_entry_reserve/release(),
886 * but when we move zalloc() over to use this function as its backend
887 * we will have to switch to kreserve/krelease and call reserve(0)
888 * after the new space is made available.
890 * Interrupt code which has preempted other code is not allowed to
891 * use PQ_CACHE pages. However, if an interrupt thread is run
892 * non-preemptively or blocks and then runs non-preemptively, then
893 * it is free to use PQ_CACHE pages.
895 * This routine will currently obtain the BGL.
898 kmem_slab_alloc(vm_size_t size, vm_offset_t align, int flags)
903 int count, vmflags, base_vmflags;
905 vm_map_t map = kernel_map;
907 size = round_page(size);
908 addr = vm_map_min(map);
911 * Reserve properly aligned space from kernel_map. RNOWAIT allocations
914 if (flags & M_RNOWAIT) {
915 if (try_mplock() == 0)
920 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
923 if (vm_map_findspace(map, vm_map_min(map), size, align, &addr)) {
925 if ((flags & M_NULLOK) == 0)
926 panic("kmem_slab_alloc(): kernel_map ran out of space!");
928 vm_map_entry_release(count);
932 offset = addr - VM_MIN_KERNEL_ADDRESS;
933 vm_object_reference(kernel_object);
934 vm_map_insert(map, &count,
935 kernel_object, offset, addr, addr + size,
936 VM_PROT_ALL, VM_PROT_ALL, 0);
942 base_vmflags |= VM_ALLOC_ZERO;
943 if (flags & M_USE_RESERVE)
944 base_vmflags |= VM_ALLOC_SYSTEM;
945 if (flags & M_USE_INTERRUPT_RESERVE)
946 base_vmflags |= VM_ALLOC_INTERRUPT;
947 if ((flags & (M_RNOWAIT|M_WAITOK)) == 0)
948 panic("kmem_slab_alloc: bad flags %08x (%p)", flags, ((int **)&size)[-1]);
952 * Allocate the pages. Do not mess with the PG_ZERO flag yet.
954 for (i = 0; i < size; i += PAGE_SIZE) {
956 vm_pindex_t idx = OFF_TO_IDX(offset + i);
959 * VM_ALLOC_NORMAL can only be set if we are not preempting.
961 * VM_ALLOC_SYSTEM is automatically set if we are preempting and
962 * M_WAITOK was specified as an alternative (i.e. M_USE_RESERVE is
963 * implied in this case), though I'm sure if we really need to do
966 vmflags = base_vmflags;
967 if (flags & M_WAITOK) {
968 if (td->td_preempted)
969 vmflags |= VM_ALLOC_SYSTEM;
971 vmflags |= VM_ALLOC_NORMAL;
974 m = vm_page_alloc(kernel_object, idx, vmflags);
977 * If the allocation failed we either return NULL or we retry.
979 * If M_WAITOK is specified we wait for more memory and retry.
980 * If M_WAITOK is specified from a preemption we yield instead of
981 * wait. Livelock will not occur because the interrupt thread
982 * will not be preempting anyone the second time around after the
986 if (flags & M_WAITOK) {
987 if (td->td_preempted) {
996 i -= PAGE_SIZE; /* retry */
1001 * We were unable to recover, cleanup and return NULL
1005 m = vm_page_lookup(kernel_object, OFF_TO_IDX(offset + i));
1008 vm_map_delete(map, addr, addr + size, &count);
1011 vm_map_entry_release(count);
1020 * Mark the map entry as non-pageable using a routine that allows us to
1021 * populate the underlying pages.
1023 vm_map_set_wired_quick(map, addr, size, &count);
1027 * Enter the pages into the pmap and deal with PG_ZERO and M_ZERO.
1029 for (i = 0; i < size; i += PAGE_SIZE) {
1032 m = vm_page_lookup(kernel_object, OFF_TO_IDX(offset + i));
1033 m->valid = VM_PAGE_BITS_ALL;
1036 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL, 1);
1037 if ((m->flags & PG_ZERO) == 0 && (flags & M_ZERO))
1038 bzero((char *)addr + i, PAGE_SIZE);
1039 vm_page_flag_clear(m, PG_ZERO);
1040 vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE | PG_REFERENCED);
1043 vm_map_entry_release(count);
1045 return((void *)addr);
1049 * kmem_slab_free() (MP SAFE) (GETS BGL)
1052 kmem_slab_free(void *ptr, vm_size_t size)
1056 vm_map_remove(kernel_map, (vm_offset_t)ptr, (vm_offset_t)ptr + size);