2 * KERN_SLABALLOC.C - Kernel SLAB memory allocator
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
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
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20 * contributors may be used to endorse or promote products derived
21 * from this software without specific, prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * $DragonFly: src/sys/kern/kern_slaballoc.c,v 1.24 2004/07/29 08:50:09 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;
126 static int ZonePageLimit;
128 static struct malloc_type *kmemstatistics;
129 static struct kmemusage *kmemusage;
130 static int32_t weirdary[16];
132 static void *kmem_slab_alloc(vm_size_t bytes, vm_offset_t align, int flags);
133 static void kmem_slab_free(void *ptr, vm_size_t bytes);
136 * Misc constants. Note that allocations that are exact multiples of
137 * PAGE_SIZE, or exceed the zone limit, fall through to the kmem module.
138 * IN_SAME_PAGE_MASK is used to sanity-check the per-page free lists.
140 #define MIN_CHUNK_SIZE 8 /* in bytes */
141 #define MIN_CHUNK_MASK (MIN_CHUNK_SIZE - 1)
142 #define ZONE_RELS_THRESH 2 /* threshold number of zones */
143 #define IN_SAME_PAGE_MASK (~(intptr_t)PAGE_MASK | MIN_CHUNK_MASK)
146 * The WEIRD_ADDR is used as known text to copy into free objects to
147 * try to create deterministic failure cases if the data is accessed after
150 #define WEIRD_ADDR 0xdeadc0de
151 #define MAX_COPY sizeof(weirdary)
152 #define ZERO_LENGTH_PTR ((void *)-8)
155 * Misc global malloc buckets
158 MALLOC_DEFINE(M_CACHE, "cache", "Various Dynamically allocated caches");
159 MALLOC_DEFINE(M_DEVBUF, "devbuf", "device driver memory");
160 MALLOC_DEFINE(M_TEMP, "temp", "misc temporary data buffers");
162 MALLOC_DEFINE(M_IP6OPT, "ip6opt", "IPv6 options");
163 MALLOC_DEFINE(M_IP6NDP, "ip6ndp", "IPv6 Neighbor Discovery");
166 * Initialize the slab memory allocator. We have to choose a zone size based
167 * on available physical memory. We choose a zone side which is approximately
168 * 1/1024th of our memory, so if we have 128MB of ram we have a zone size of
169 * 128K. The zone size is limited to the bounds set in slaballoc.h
170 * (typically 32K min, 128K max).
172 static void kmeminit(void *dummy);
174 SYSINIT(kmem, SI_SUB_KMEM, SI_ORDER_FIRST, kmeminit, NULL)
177 kmeminit(void *dummy)
184 limsize = (vm_poff_t)vmstats.v_page_count * PAGE_SIZE;
185 if (limsize > VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS)
186 limsize = VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS;
188 usesize = (int)(limsize / 1024); /* convert to KB */
190 ZoneSize = ZALLOC_MIN_ZONE_SIZE;
191 while (ZoneSize < ZALLOC_MAX_ZONE_SIZE && (ZoneSize << 1) < usesize)
193 ZoneLimit = ZoneSize / 4;
194 if (ZoneLimit > ZALLOC_ZONE_LIMIT)
195 ZoneLimit = ZALLOC_ZONE_LIMIT;
196 ZoneMask = ZoneSize - 1;
197 ZonePageLimit = PAGE_SIZE * 4;
198 ZonePageCount = ZoneSize / PAGE_SIZE;
200 npg = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE;
201 kmemusage = kmem_slab_alloc(npg * sizeof(struct kmemusage), PAGE_SIZE, M_WAITOK|M_ZERO);
203 for (i = 0; i < arysize(weirdary); ++i)
204 weirdary[i] = WEIRD_ADDR;
207 printf("Slab ZoneSize set to %dKB\n", ZoneSize / 1024);
211 * Initialize a malloc type tracking structure.
214 malloc_init(void *data)
216 struct malloc_type *type = data;
219 if (type->ks_magic != M_MAGIC)
220 panic("malloc type lacks magic");
222 if (type->ks_limit != 0)
225 if (vmstats.v_page_count == 0)
226 panic("malloc_init not allowed before vm init");
228 limsize = (vm_poff_t)vmstats.v_page_count * PAGE_SIZE;
229 if (limsize > VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS)
230 limsize = VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS;
231 type->ks_limit = limsize / 10;
233 type->ks_next = kmemstatistics;
234 kmemstatistics = type;
238 malloc_uninit(void *data)
240 struct malloc_type *type = data;
241 struct malloc_type *t;
247 if (type->ks_magic != M_MAGIC)
248 panic("malloc type lacks magic");
250 if (vmstats.v_page_count == 0)
251 panic("malloc_uninit not allowed before vm init");
253 if (type->ks_limit == 0)
254 panic("malloc_uninit on uninitialized type");
258 * memuse is only correct in aggregation. Due to memory being allocated
259 * on one cpu and freed on another individual array entries may be
260 * negative or positive (canceling each other out).
262 for (i = ttl = 0; i < ncpus; ++i)
263 ttl += type->ks_memuse[i];
265 printf("malloc_uninit: %ld bytes of '%s' still allocated on cpu %d\n",
266 ttl, type->ks_shortdesc, i);
269 if (type == kmemstatistics) {
270 kmemstatistics = type->ks_next;
272 for (t = kmemstatistics; t->ks_next != NULL; t = t->ks_next) {
273 if (t->ks_next == type) {
274 t->ks_next = type->ks_next;
279 type->ks_next = NULL;
284 * Calculate the zone index for the allocation request size and set the
285 * allocation request size to that particular zone's chunk size.
288 zoneindex(unsigned long *bytes)
290 unsigned int n = (unsigned int)*bytes; /* unsigned for shift opt */
292 *bytes = n = (n + 7) & ~7;
293 return(n / 8 - 1); /* 8 byte chunks, 16 zones */
296 *bytes = n = (n + 15) & ~15;
301 *bytes = n = (n + 31) & ~31;
305 *bytes = n = (n + 63) & ~63;
309 *bytes = n = (n + 127) & ~127;
310 return(n / 128 + 31);
313 *bytes = n = (n + 255) & ~255;
314 return(n / 256 + 39);
316 *bytes = n = (n + 511) & ~511;
317 return(n / 512 + 47);
319 #if ZALLOC_ZONE_LIMIT > 8192
321 *bytes = n = (n + 1023) & ~1023;
322 return(n / 1024 + 55);
325 #if ZALLOC_ZONE_LIMIT > 16384
327 *bytes = n = (n + 2047) & ~2047;
328 return(n / 2048 + 63);
331 panic("Unexpected byte count %d", n);
336 * malloc() (SLAB ALLOCATOR)
338 * Allocate memory via the slab allocator. If the request is too large,
339 * or if it page-aligned beyond a certain size, we fall back to the
340 * KMEM subsystem. A SLAB tracking descriptor must be specified, use
341 * &SlabMisc if you don't care.
343 * M_RNOWAIT - return NULL instead of blocking.
344 * M_ZERO - zero the returned memory.
345 * M_USE_RESERVE - allow greater drawdown of the free list
346 * M_USE_INTERRUPT_RESERVE - allow the freelist to be exhausted
348 * M_FAILSAFE - Failsafe allocation, when the allocation must
349 * succeed attemp to get out of any preemption context
350 * and allocate from the cache, else block (even though
351 * we might be blocking from an interrupt), or panic.
354 malloc(unsigned long size, struct malloc_type *type, int flags)
359 struct globaldata *gd;
366 * XXX silly to have this in the critical path.
368 if (type->ks_limit == 0) {
370 if (type->ks_limit == 0)
377 * Handle the case where the limit is reached. Panic if can't return
378 * NULL. XXX the original malloc code looped, but this tended to
379 * simply deadlock the computer.
381 while (type->ks_loosememuse >= type->ks_limit) {
385 for (i = ttl = 0; i < ncpus; ++i)
386 ttl += type->ks_memuse[i];
387 type->ks_loosememuse = ttl;
388 if (ttl >= type->ks_limit) {
389 if (flags & (M_RNOWAIT|M_NULLOK))
391 panic("%s: malloc limit exceeded", type->ks_shortdesc);
396 * Handle the degenerate size == 0 case. Yes, this does happen.
397 * Return a special pointer. This is to maintain compatibility with
398 * the original malloc implementation. Certain devices, such as the
399 * adaptec driver, not only allocate 0 bytes, they check for NULL and
400 * also realloc() later on. Joy.
403 return(ZERO_LENGTH_PTR);
406 * Handle hysteresis from prior frees here in malloc(). We cannot
407 * safely manipulate the kernel_map in free() due to free() possibly
408 * being called via an IPI message or from sensitive interrupt code.
410 while (slgd->NFreeZones > ZONE_RELS_THRESH && (flags & M_RNOWAIT) == 0) {
412 if (slgd->NFreeZones > ZONE_RELS_THRESH) { /* crit sect race */
414 slgd->FreeZones = z->z_Next;
416 kmem_slab_free(z, ZoneSize); /* may block */
421 * XXX handle oversized frees that were queued from free().
423 while (slgd->FreeOvZones && (flags & M_RNOWAIT) == 0) {
425 if ((z = slgd->FreeOvZones) != NULL) {
426 KKASSERT(z->z_Magic == ZALLOC_OVSZ_MAGIC);
427 slgd->FreeOvZones = z->z_Next;
428 kmem_slab_free(z, z->z_ChunkSize); /* may block */
434 * Handle large allocations directly. There should not be very many of
435 * these so performance is not a big issue.
437 * Guarentee page alignment for allocations in multiples of PAGE_SIZE
439 if (size >= ZoneLimit || (size & PAGE_MASK) == 0) {
440 struct kmemusage *kup;
442 size = round_page(size);
443 chunk = kmem_slab_alloc(size, PAGE_SIZE, flags);
446 flags &= ~M_ZERO; /* result already zero'd if M_ZERO was set */
447 flags |= M_PASSIVE_ZERO;
449 kup->ku_pagecnt = size / PAGE_SIZE;
450 kup->ku_cpu = gd->gd_cpuid;
456 * Attempt to allocate out of an existing zone. First try the free list,
457 * then allocate out of unallocated space. If we find a good zone move
458 * it to the head of the list so later allocations find it quickly
459 * (we might have thousands of zones in the list).
461 * Note: zoneindex() will panic of size is too large.
463 zi = zoneindex(&size);
464 KKASSERT(zi < NZONES);
466 if ((z = slgd->ZoneAry[zi]) != NULL) {
467 KKASSERT(z->z_NFree > 0);
470 * Remove us from the ZoneAry[] when we become empty
472 if (--z->z_NFree == 0) {
473 slgd->ZoneAry[zi] = z->z_Next;
478 * Locate a chunk in a free page. This attempts to localize
479 * reallocations into earlier pages without us having to sort
480 * the chunk list. A chunk may still overlap a page boundary.
482 while (z->z_FirstFreePg < ZonePageCount) {
483 if ((chunk = z->z_PageAry[z->z_FirstFreePg]) != NULL) {
486 * Diagnostic: c_Next is not total garbage.
488 KKASSERT(chunk->c_Next == NULL ||
489 ((intptr_t)chunk->c_Next & IN_SAME_PAGE_MASK) ==
490 ((intptr_t)chunk & IN_SAME_PAGE_MASK));
493 if ((uintptr_t)chunk < VM_MIN_KERNEL_ADDRESS)
494 panic("chunk %p FFPG %d/%d", chunk, z->z_FirstFreePg, ZonePageCount);
495 if (chunk->c_Next && (uintptr_t)chunk->c_Next < VM_MIN_KERNEL_ADDRESS)
496 panic("chunkNEXT %p %p FFPG %d/%d", chunk, chunk->c_Next, z->z_FirstFreePg, ZonePageCount);
498 z->z_PageAry[z->z_FirstFreePg] = chunk->c_Next;
505 * No chunks are available but NFree said we had some memory, so
506 * it must be available in the never-before-used-memory area
507 * governed by UIndex. The consequences are very serious if our zone
508 * got corrupted so we use an explicit panic rather then a KASSERT.
510 if (z->z_UIndex + 1 != z->z_NMax)
511 z->z_UIndex = z->z_UIndex + 1;
514 if (z->z_UIndex == z->z_UEndIndex)
515 panic("slaballoc: corrupted zone");
516 chunk = (SLChunk *)(z->z_BasePtr + z->z_UIndex * size);
517 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) {
519 flags |= M_PASSIVE_ZERO;
525 * If all zones are exhausted we need to allocate a new zone for this
526 * index. Use M_ZERO to take advantage of pre-zerod pages. Also see
527 * UAlloc use above in regards to M_ZERO. Note that when we are reusing
528 * a zone from the FreeZones list UAlloc'd data will not be zero'd, and
529 * we do not pre-zero it because we do not want to mess up the L1 cache.
531 * At least one subsystem, the tty code (see CROUND) expects power-of-2
532 * allocations to be power-of-2 aligned. We maintain compatibility by
533 * adjusting the base offset below.
538 if ((z = slgd->FreeZones) != NULL) {
539 slgd->FreeZones = z->z_Next;
541 bzero(z, sizeof(SLZone));
542 z->z_Flags |= SLZF_UNOTZEROD;
544 z = kmem_slab_alloc(ZoneSize, ZoneSize, flags|M_ZERO);
550 * Guarentee power-of-2 alignment for power-of-2-sized chunks.
551 * Otherwise just 8-byte align the data.
553 if ((size | (size - 1)) + 1 == (size << 1))
554 off = (sizeof(SLZone) + size - 1) & ~(size - 1);
556 off = (sizeof(SLZone) + MIN_CHUNK_MASK) & ~MIN_CHUNK_MASK;
557 z->z_Magic = ZALLOC_SLAB_MAGIC;
559 z->z_NMax = (ZoneSize - off) / size;
560 z->z_NFree = z->z_NMax - 1;
561 z->z_BasePtr = (char *)z + off;
562 z->z_UIndex = z->z_UEndIndex = slgd->JunkIndex % z->z_NMax;
563 z->z_ChunkSize = size;
564 z->z_FirstFreePg = ZonePageCount;
566 z->z_Cpu = gd->gd_cpuid;
567 chunk = (SLChunk *)(z->z_BasePtr + z->z_UIndex * size);
568 z->z_Next = slgd->ZoneAry[zi];
569 slgd->ZoneAry[zi] = z;
570 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) {
571 flags &= ~M_ZERO; /* already zero'd */
572 flags |= M_PASSIVE_ZERO;
576 * Slide the base index for initial allocations out of the next
577 * zone we create so we do not over-weight the lower part of the
580 slgd->JunkIndex = (slgd->JunkIndex + ZALLOC_SLAB_SLIDE)
581 & (ZALLOC_MAX_ZONE_SIZE - 1);
584 ++type->ks_inuse[gd->gd_cpuid];
585 type->ks_memuse[gd->gd_cpuid] += size;
586 type->ks_loosememuse += size;
591 else if ((flags & (M_ZERO|M_PASSIVE_ZERO)) == 0)
592 chunk->c_Next = (void *)-1; /* avoid accidental double-free check */
601 realloc(void *ptr, unsigned long size, struct malloc_type *type, int flags)
607 KKASSERT((flags & M_ZERO) == 0); /* not supported */
609 if (ptr == NULL || ptr == ZERO_LENGTH_PTR)
610 return(malloc(size, type, flags));
617 * Handle oversized allocations. XXX we really should require that a
618 * size be passed to free() instead of this nonsense.
621 struct kmemusage *kup;
624 if (kup->ku_pagecnt) {
625 osize = kup->ku_pagecnt << PAGE_SHIFT;
626 if (osize == round_page(size))
628 if ((nptr = malloc(size, type, flags)) == NULL)
630 bcopy(ptr, nptr, min(size, osize));
637 * Get the original allocation's zone. If the new request winds up
638 * using the same chunk size we do not have to do anything.
640 z = (SLZone *)((uintptr_t)ptr & ~(uintptr_t)ZoneMask);
641 KKASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC);
644 if (z->z_ChunkSize == size)
648 * Allocate memory for the new request size. Note that zoneindex has
649 * already adjusted the request size to the appropriate chunk size, which
650 * should optimize our bcopy(). Then copy and return the new pointer.
652 if ((nptr = malloc(size, type, flags)) == NULL)
654 bcopy(ptr, nptr, min(size, z->z_ChunkSize));
660 strdup(const char *str, struct malloc_type *type)
662 int zlen; /* length inclusive of terminating NUL */
667 zlen = strlen(str) + 1;
668 nstr = malloc(zlen, type, M_WAITOK);
669 bcopy(str, nstr, zlen);
675 * free() (SLAB ALLOCATOR)
677 * Free the specified chunk of memory.
681 free_remote(void *ptr)
683 free(ptr, *(struct malloc_type **)ptr);
689 free(void *ptr, struct malloc_type *type)
694 struct globaldata *gd;
701 panic("trying to free NULL pointer");
704 * Handle special 0-byte allocations
706 if (ptr == ZERO_LENGTH_PTR)
710 * Handle oversized allocations. XXX we really should require that a
711 * size be passed to free() instead of this nonsense.
713 * This code is never called via an ipi.
716 struct kmemusage *kup;
720 if (kup->ku_pagecnt) {
721 size = kup->ku_pagecnt << PAGE_SHIFT;
724 KKASSERT(sizeof(weirdary) <= size);
725 bcopy(weirdary, ptr, sizeof(weirdary));
728 * note: we always adjust our cpu's slot, not the originating
729 * cpu (kup->ku_cpuid). The statistics are in aggregate.
731 * note: XXX we have still inherited the interrupts-can't-block
732 * assumption. An interrupt thread does not bump
733 * gd_intr_nesting_level so check TDF_INTTHREAD. This is
734 * primarily until we can fix softupdate's assumptions about free().
737 --type->ks_inuse[gd->gd_cpuid];
738 type->ks_memuse[gd->gd_cpuid] -= size;
739 if (mycpu->gd_intr_nesting_level || (gd->gd_curthread->td_flags & TDF_INTTHREAD)) {
741 z->z_Magic = ZALLOC_OVSZ_MAGIC;
742 z->z_Next = slgd->FreeOvZones;
743 z->z_ChunkSize = size;
744 slgd->FreeOvZones = z;
748 kmem_slab_free(ptr, size); /* may block */
755 * Zone case. Figure out the zone based on the fact that it is
758 z = (SLZone *)((uintptr_t)ptr & ~(uintptr_t)ZoneMask);
759 KKASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC);
762 * If we do not own the zone then forward the request to the
765 if (z->z_CpuGd != gd) {
766 *(struct malloc_type **)ptr = type;
768 lwkt_send_ipiq(z->z_CpuGd, free_remote, ptr);
770 panic("Corrupt SLZone");
775 if (type->ks_magic != M_MAGIC)
776 panic("free: malloc type lacks magic");
779 pgno = ((char *)ptr - (char *)z) >> PAGE_SHIFT;
784 * Attempt to detect a double-free. To reduce overhead we only check
785 * if there appears to be link pointer at the base of the data.
787 if (((intptr_t)chunk->c_Next - (intptr_t)z) >> PAGE_SHIFT == pgno) {
789 for (scan = z->z_PageAry[pgno]; scan; scan = scan->c_Next) {
791 panic("Double free at %p", chunk);
797 * Put weird data into the memory to detect modifications after freeing,
798 * illegal pointer use after freeing (we should fault on the odd address),
799 * and so forth. XXX needs more work, see the old malloc code.
802 if (z->z_ChunkSize < sizeof(weirdary))
803 bcopy(weirdary, chunk, z->z_ChunkSize);
805 bcopy(weirdary, chunk, sizeof(weirdary));
809 * Add this free non-zero'd chunk to a linked list for reuse, adjust
813 if ((uintptr_t)chunk < VM_MIN_KERNEL_ADDRESS)
814 panic("BADFREE %p", chunk);
816 chunk->c_Next = z->z_PageAry[pgno];
817 z->z_PageAry[pgno] = chunk;
819 if (chunk->c_Next && (uintptr_t)chunk->c_Next < VM_MIN_KERNEL_ADDRESS)
822 if (z->z_FirstFreePg > pgno)
823 z->z_FirstFreePg = pgno;
826 * Bump the number of free chunks. If it becomes non-zero the zone
827 * must be added back onto the appropriate list.
829 if (z->z_NFree++ == 0) {
830 z->z_Next = slgd->ZoneAry[z->z_ZoneIndex];
831 slgd->ZoneAry[z->z_ZoneIndex] = z;
834 --type->ks_inuse[z->z_Cpu];
835 type->ks_memuse[z->z_Cpu] -= z->z_ChunkSize;
838 * If the zone becomes totally free, and there are other zones we
839 * can allocate from, move this zone to the FreeZones list. Since
840 * this code can be called from an IPI callback, do *NOT* try to mess
841 * with kernel_map here. Hysteresis will be performed at malloc() time.
843 if (z->z_NFree == z->z_NMax &&
844 (z->z_Next || slgd->ZoneAry[z->z_ZoneIndex] != z)
848 for (pz = &slgd->ZoneAry[z->z_ZoneIndex]; z != *pz; pz = &(*pz)->z_Next)
852 z->z_Next = slgd->FreeZones;
862 * Directly allocate and wire kernel memory in PAGE_SIZE chunks with the
863 * specified alignment. M_* flags are expected in the flags field.
865 * Alignment must be a multiple of PAGE_SIZE.
867 * NOTE! XXX For the moment we use vm_map_entry_reserve/release(),
868 * but when we move zalloc() over to use this function as its backend
869 * we will have to switch to kreserve/krelease and call reserve(0)
870 * after the new space is made available.
872 * Interrupt code which has preempted other code is not allowed to
873 * message with CACHE pages, but if M_FAILSAFE is set we can do a
874 * yield to become non-preempting and try again inclusive of
878 kmem_slab_alloc(vm_size_t size, vm_offset_t align, int flags)
885 vm_map_t map = kernel_map;
887 size = round_page(size);
888 addr = vm_map_min(map);
891 * Reserve properly aligned space from kernel_map
893 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
896 if (vm_map_findspace(map, vm_map_min(map), size, align, &addr)) {
898 if ((flags & (M_RNOWAIT|M_NULLOK)) == 0)
899 panic("kmem_slab_alloc(): kernel_map ran out of space!");
901 vm_map_entry_release(count);
902 if ((flags & (M_FAILSAFE|M_NULLOK)) == M_FAILSAFE)
903 panic("kmem_slab_alloc(): kernel_map ran out of space!");
906 offset = addr - VM_MIN_KERNEL_ADDRESS;
907 vm_object_reference(kernel_object);
908 vm_map_insert(map, &count,
909 kernel_object, offset, addr, addr + size,
910 VM_PROT_ALL, VM_PROT_ALL, 0);
915 * Allocate the pages. Do not mess with the PG_ZERO flag yet.
917 for (i = 0; i < size; i += PAGE_SIZE) {
919 vm_pindex_t idx = OFF_TO_IDX(offset + i);
923 vmflags |= VM_ALLOC_ZERO;
924 if (flags & M_USE_RESERVE)
925 vmflags |= VM_ALLOC_SYSTEM;
926 if (flags & M_USE_INTERRUPT_RESERVE)
927 vmflags |= VM_ALLOC_INTERRUPT;
928 if ((flags & (M_RNOWAIT|M_WAITOK)) == 0)
929 panic("kmem_slab_alloc: bad flags %08x (%p)", flags, ((int **)&size)[-1]);
932 * Never set VM_ALLOC_NORMAL during a preemption because this allows
933 * allocation out of the VM page cache and could cause mainline kernel
934 * code working on VM objects to get confused.
936 if (flags & (M_FAILSAFE|M_WAITOK)) {
937 if (td->td_preempted) {
938 vmflags |= VM_ALLOC_SYSTEM;
940 vmflags |= VM_ALLOC_NORMAL;
944 m = vm_page_alloc(kernel_object, idx, vmflags);
947 * If the allocation failed we either return NULL or we retry.
949 * If M_WAITOK or M_FAILSAFE is set we retry. Note that M_WAITOK
950 * (and M_FAILSAFE) can be specified from an interrupt. M_FAILSAFE
951 * generates a warning or a panic.
953 * If we are preempting a thread we yield instead of block. Both
954 * gets us out from under a preemption but yielding will get cpu
955 * back more quicker. Livelock does not occur because we will not
956 * be preempting anyone the second time around.
960 if (flags & (M_FAILSAFE|M_WAITOK)) {
961 if (td->td_preempted) {
962 if (flags & M_FAILSAFE) {
963 printf("malloc: M_WAITOK from preemption would block"
964 " try failsafe yield/block\n");
974 i -= PAGE_SIZE; /* retry */
979 * We were unable to recover, cleanup and return NULL
983 m = vm_page_lookup(kernel_object, OFF_TO_IDX(offset + i));
986 vm_map_delete(map, addr, addr + size, &count);
989 vm_map_entry_release(count);
997 * Mark the map entry as non-pageable using a routine that allows us to
998 * populate the underlying pages.
1000 vm_map_set_wired_quick(map, addr, size, &count);
1004 * Enter the pages into the pmap and deal with PG_ZERO and M_ZERO.
1006 for (i = 0; i < size; i += PAGE_SIZE) {
1009 m = vm_page_lookup(kernel_object, OFF_TO_IDX(offset + i));
1010 m->valid = VM_PAGE_BITS_ALL;
1013 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL, 1);
1014 if ((m->flags & PG_ZERO) == 0 && (flags & M_ZERO))
1015 bzero((char *)addr + i, PAGE_SIZE);
1016 vm_page_flag_clear(m, PG_ZERO);
1017 vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE | PG_REFERENCED);
1020 vm_map_entry_release(count);
1021 return((void *)addr);
1025 kmem_slab_free(void *ptr, vm_size_t size)
1028 vm_map_remove(kernel_map, (vm_offset_t)ptr, (vm_offset_t)ptr + size);