FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_malloc.c

     /*-
      * Copyright (c) 1987, 1991, 1993
      *      The Regents of the University of California.
      * Copyright (c) 2005-2009 Robert N. M. Watson
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_malloc.c       8.3 (Berkeley) 1/4/94
     */
    
    /*
     * Kernel malloc(9) implementation -- general purpose kernel memory allocator
     * based on memory types.  Back end is implemented using the UMA(9) zone
     * allocator.  A set of fixed-size buckets are used for smaller allocations,
     * and a special UMA allocation interface is used for larger allocations.
     * Callers declare memory types, and statistics are maintained independently
     * for each memory type.  Statistics are maintained per-CPU for performance
     * reasons.  See malloc(9) and comments in malloc.h for a detailed
     * description.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_malloc.c 300262 2016-05-20 04:45:08Z markj $");
    
    #include "opt_ddb.h"
    #include "opt_vm.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/vmmeter.h>
    #include <sys/proc.h>
    #include <sys/sbuf.h>
    #include <sys/sysctl.h>
    #include <sys/time.h>
    #include <sys/vmem.h>
    
    #include <vm/vm.h>
    #include <vm/pmap.h>
    #include <vm/vm_pageout.h>
    #include <vm/vm_param.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_map.h>
    #include <vm/vm_page.h>
    #include <vm/uma.h>
    #include <vm/uma_int.h>
    #include <vm/uma_dbg.h>
    
    #ifdef DEBUG_MEMGUARD
    #include <vm/memguard.h>
    #endif
    #ifdef DEBUG_REDZONE
    #include <vm/redzone.h>
    #endif
    
    #if defined(INVARIANTS) && defined(__i386__)
    #include <machine/cpu.h>
    #endif
    
    #include <ddb/ddb.h>
    
    #ifdef KDTRACE_HOOKS
    #include <sys/dtrace_bsd.h>
    
    dtrace_malloc_probe_func_t      dtrace_malloc_probe;
    #endif
    
    /*
     * When realloc() is called, if the new size is sufficiently smaller than
     * the old size, realloc() will allocate a new, smaller block to avoid
     * wasting memory. 'Sufficiently smaller' is defined as: newsize <=
    * oldsize / 2^n, where REALLOC_FRACTION defines the value of 'n'.
    */
   #ifndef REALLOC_FRACTION
   #define REALLOC_FRACTION        1       /* new block if <= half the size */
   #endif
   
   /*
    * Centrally define some common malloc types.
    */
   MALLOC_DEFINE(M_CACHE, "cache", "Various Dynamically allocated caches");
   MALLOC_DEFINE(M_DEVBUF, "devbuf", "device driver memory");
   MALLOC_DEFINE(M_TEMP, "temp", "misc temporary data buffers");
   
   static struct malloc_type *kmemstatistics;
   static int kmemcount;
   
   #define KMEM_ZSHIFT     4
   #define KMEM_ZBASE      16
   #define KMEM_ZMASK      (KMEM_ZBASE - 1)
   
   #define KMEM_ZMAX       65536
   #define KMEM_ZSIZE      (KMEM_ZMAX >> KMEM_ZSHIFT)
   static uint8_t kmemsize[KMEM_ZSIZE + 1];
   
   #ifndef MALLOC_DEBUG_MAXZONES
   #define MALLOC_DEBUG_MAXZONES   1
   #endif
   static int numzones = MALLOC_DEBUG_MAXZONES;
   
   /*
    * Small malloc(9) memory allocations are allocated from a set of UMA buckets
    * of various sizes.
    *
    * XXX: The comment here used to read "These won't be powers of two for
    * long."  It's possible that a significant amount of wasted memory could be
    * recovered by tuning the sizes of these buckets.
    */
   struct {
           int kz_size;
           char *kz_name;
           uma_zone_t kz_zone[MALLOC_DEBUG_MAXZONES];
   } kmemzones[] = {
           {16, "16", },
           {32, "32", },
           {64, "64", },
           {128, "128", },
           {256, "256", },
           {512, "512", },
           {1024, "1024", },
           {2048, "2048", },
           {4096, "4096", },
           {8192, "8192", },
           {16384, "16384", },
           {32768, "32768", },
           {65536, "65536", },
           {0, NULL},
   };
   
   /*
    * Zone to allocate malloc type descriptions from.  For ABI reasons, memory
    * types are described by a data structure passed by the declaring code, but
    * the malloc(9) implementation has its own data structure describing the
    * type and statistics.  This permits the malloc(9)-internal data structures
    * to be modified without breaking binary-compiled kernel modules that
    * declare malloc types.
    */
   static uma_zone_t mt_zone;
   
   u_long vm_kmem_size;
   SYSCTL_ULONG(_vm, OID_AUTO, kmem_size, CTLFLAG_RDTUN, &vm_kmem_size, 0,
       "Size of kernel memory");
   
   static u_long kmem_zmax = KMEM_ZMAX;
   SYSCTL_ULONG(_vm, OID_AUTO, kmem_zmax, CTLFLAG_RDTUN, &kmem_zmax, 0,
       "Maximum allocation size that malloc(9) would use UMA as backend");
   
   static u_long vm_kmem_size_min;
   SYSCTL_ULONG(_vm, OID_AUTO, kmem_size_min, CTLFLAG_RDTUN, &vm_kmem_size_min, 0,
       "Minimum size of kernel memory");
   
   static u_long vm_kmem_size_max;
   SYSCTL_ULONG(_vm, OID_AUTO, kmem_size_max, CTLFLAG_RDTUN, &vm_kmem_size_max, 0,
       "Maximum size of kernel memory");
   
   static u_int vm_kmem_size_scale;
   SYSCTL_UINT(_vm, OID_AUTO, kmem_size_scale, CTLFLAG_RDTUN, &vm_kmem_size_scale, 0,
       "Scale factor for kernel memory size");
   
   static int sysctl_kmem_map_size(SYSCTL_HANDLER_ARGS);
   SYSCTL_PROC(_vm, OID_AUTO, kmem_map_size,
       CTLFLAG_RD | CTLTYPE_ULONG | CTLFLAG_MPSAFE, NULL, 0,
       sysctl_kmem_map_size, "LU", "Current kmem allocation size");
   
   static int sysctl_kmem_map_free(SYSCTL_HANDLER_ARGS);
   SYSCTL_PROC(_vm, OID_AUTO, kmem_map_free,
       CTLFLAG_RD | CTLTYPE_ULONG | CTLFLAG_MPSAFE, NULL, 0,
       sysctl_kmem_map_free, "LU", "Free space in kmem");
   
   /*
    * The malloc_mtx protects the kmemstatistics linked list.
    */
   struct mtx malloc_mtx;
   
   #ifdef MALLOC_PROFILE
   uint64_t krequests[KMEM_ZSIZE + 1];
   
   static int sysctl_kern_mprof(SYSCTL_HANDLER_ARGS);
   #endif
   
   static int sysctl_kern_malloc_stats(SYSCTL_HANDLER_ARGS);
   
   /*
    * time_uptime of the last malloc(9) failure (induced or real).
    */
   static time_t t_malloc_fail;
   
   #if defined(MALLOC_MAKE_FAILURES) || (MALLOC_DEBUG_MAXZONES > 1)
   static SYSCTL_NODE(_debug, OID_AUTO, malloc, CTLFLAG_RD, 0,
       "Kernel malloc debugging options");
   #endif
   
   /*
    * malloc(9) fault injection -- cause malloc failures every (n) mallocs when
    * the caller specifies M_NOWAIT.  If set to 0, no failures are caused.
    */
   #ifdef MALLOC_MAKE_FAILURES
   static int malloc_failure_rate;
   static int malloc_nowait_count;
   static int malloc_failure_count;
   SYSCTL_INT(_debug_malloc, OID_AUTO, failure_rate, CTLFLAG_RWTUN,
       &malloc_failure_rate, 0, "Every (n) mallocs with M_NOWAIT will fail");
   SYSCTL_INT(_debug_malloc, OID_AUTO, failure_count, CTLFLAG_RD,
       &malloc_failure_count, 0, "Number of imposed M_NOWAIT malloc failures");
   #endif
   
   static int
   sysctl_kmem_map_size(SYSCTL_HANDLER_ARGS)
   {
           u_long size;
   
           size = vmem_size(kmem_arena, VMEM_ALLOC);
           return (sysctl_handle_long(oidp, &size, 0, req));
   }
   
   static int
   sysctl_kmem_map_free(SYSCTL_HANDLER_ARGS)
   {
           u_long size;
   
           size = vmem_size(kmem_arena, VMEM_FREE);
           return (sysctl_handle_long(oidp, &size, 0, req));
   }
   
   /*
    * malloc(9) uma zone separation -- sub-page buffer overruns in one
    * malloc type will affect only a subset of other malloc types.
    */
   #if MALLOC_DEBUG_MAXZONES > 1
   static void
   tunable_set_numzones(void)
   {
   
           TUNABLE_INT_FETCH("debug.malloc.numzones",
               &numzones);
   
           /* Sanity check the number of malloc uma zones. */
           if (numzones <= 0)
                   numzones = 1;
           if (numzones > MALLOC_DEBUG_MAXZONES)
                   numzones = MALLOC_DEBUG_MAXZONES;
   }
   SYSINIT(numzones, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_set_numzones, NULL);
   SYSCTL_INT(_debug_malloc, OID_AUTO, numzones, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
       &numzones, 0, "Number of malloc uma subzones");
   
   /*
    * Any number that changes regularly is an okay choice for the
    * offset.  Build numbers are pretty good of you have them.
    */
   static u_int zone_offset = __FreeBSD_version;
   TUNABLE_INT("debug.malloc.zone_offset", &zone_offset);
   SYSCTL_UINT(_debug_malloc, OID_AUTO, zone_offset, CTLFLAG_RDTUN,
       &zone_offset, 0, "Separate malloc types by examining the "
       "Nth character in the malloc type short description.");
   
   static u_int
   mtp_get_subzone(const char *desc)
   {
           size_t len;
           u_int val;
   
           if (desc == NULL || (len = strlen(desc)) == 0)
                   return (0);
           val = desc[zone_offset % len];
           return (val % numzones);
   }
   #elif MALLOC_DEBUG_MAXZONES == 0
   #error "MALLOC_DEBUG_MAXZONES must be positive."
   #else
   static inline u_int
   mtp_get_subzone(const char *desc)
   {
   
           return (0);
   }
   #endif /* MALLOC_DEBUG_MAXZONES > 1 */
   
   int
   malloc_last_fail(void)
   {
   
           return (time_uptime - t_malloc_fail);
   }
   
   /*
    * An allocation has succeeded -- update malloc type statistics for the
    * amount of bucket size.  Occurs within a critical section so that the
    * thread isn't preempted and doesn't migrate while updating per-PCU
    * statistics.
    */
   static void
   malloc_type_zone_allocated(struct malloc_type *mtp, unsigned long size,
       int zindx)
   {
           struct malloc_type_internal *mtip;
           struct malloc_type_stats *mtsp;
   
           critical_enter();
           mtip = mtp->ks_handle;
           mtsp = &mtip->mti_stats[curcpu];
           if (size > 0) {
                   mtsp->mts_memalloced += size;
                   mtsp->mts_numallocs++;
           }
           if (zindx != -1)
                   mtsp->mts_size |= 1 << zindx;
   
   #ifdef KDTRACE_HOOKS
           if (dtrace_malloc_probe != NULL) {
                   uint32_t probe_id = mtip->mti_probes[DTMALLOC_PROBE_MALLOC];
                   if (probe_id != 0)
                           (dtrace_malloc_probe)(probe_id,
                               (uintptr_t) mtp, (uintptr_t) mtip,
                               (uintptr_t) mtsp, size, zindx);
           }
   #endif
   
           critical_exit();
   }
   
   void
   malloc_type_allocated(struct malloc_type *mtp, unsigned long size)
   {
   
           if (size > 0)
                   malloc_type_zone_allocated(mtp, size, -1);
   }
   
   /*
    * A free operation has occurred -- update malloc type statistics for the
    * amount of the bucket size.  Occurs within a critical section so that the
    * thread isn't preempted and doesn't migrate while updating per-CPU
    * statistics.
    */
   void
   malloc_type_freed(struct malloc_type *mtp, unsigned long size)
   {
           struct malloc_type_internal *mtip;
           struct malloc_type_stats *mtsp;
   
           critical_enter();
           mtip = mtp->ks_handle;
           mtsp = &mtip->mti_stats[curcpu];
           mtsp->mts_memfreed += size;
           mtsp->mts_numfrees++;
   
   #ifdef KDTRACE_HOOKS
           if (dtrace_malloc_probe != NULL) {
                   uint32_t probe_id = mtip->mti_probes[DTMALLOC_PROBE_FREE];
                   if (probe_id != 0)
                           (dtrace_malloc_probe)(probe_id,
                               (uintptr_t) mtp, (uintptr_t) mtip,
                               (uintptr_t) mtsp, size, 0);
           }
   #endif
   
           critical_exit();
   }
   
   /*
    *      contigmalloc:
    *
    *      Allocate a block of physically contiguous memory.
    *
    *      If M_NOWAIT is set, this routine will not block and return NULL if
    *      the allocation fails.
    */
   void *
   contigmalloc(unsigned long size, struct malloc_type *type, int flags,
       vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
       vm_paddr_t boundary)
   {
           void *ret;
   
           ret = (void *)kmem_alloc_contig(kernel_arena, size, flags, low, high,
               alignment, boundary, VM_MEMATTR_DEFAULT);
           if (ret != NULL)
                   malloc_type_allocated(type, round_page(size));
           return (ret);
   }
   
   /*
    *      contigfree:
    *
    *      Free a block of memory allocated by contigmalloc.
    *
    *      This routine may not block.
    */
   void
   contigfree(void *addr, unsigned long size, struct malloc_type *type)
   {
   
           kmem_free(kernel_arena, (vm_offset_t)addr, size);
           malloc_type_freed(type, round_page(size));
   }
   
   /*
    *      malloc:
    *
    *      Allocate a block of memory.
    *
    *      If M_NOWAIT is set, this routine will not block and return NULL if
    *      the allocation fails.
    */
   void *
   malloc(unsigned long size, struct malloc_type *mtp, int flags)
   {
           int indx;
           struct malloc_type_internal *mtip;
           caddr_t va;
           uma_zone_t zone;
   #if defined(DIAGNOSTIC) || defined(DEBUG_REDZONE)
           unsigned long osize = size;
   #endif
   
   #ifdef INVARIANTS
           KASSERT(mtp->ks_magic == M_MAGIC, ("malloc: bad malloc type magic"));
           /*
            * Check that exactly one of M_WAITOK or M_NOWAIT is specified.
            */
           indx = flags & (M_WAITOK | M_NOWAIT);
           if (indx != M_NOWAIT && indx != M_WAITOK) {
                   static  struct timeval lasterr;
                   static  int curerr, once;
                   if (once == 0 && ppsratecheck(&lasterr, &curerr, 1)) {
                           printf("Bad malloc flags: %x\n", indx);
                           kdb_backtrace();
                           flags |= M_WAITOK;
                           once++;
                   }
           }
   #endif
   #ifdef MALLOC_MAKE_FAILURES
           if ((flags & M_NOWAIT) && (malloc_failure_rate != 0)) {
                   atomic_add_int(&malloc_nowait_count, 1);
                   if ((malloc_nowait_count % malloc_failure_rate) == 0) {
                           atomic_add_int(&malloc_failure_count, 1);
                           t_malloc_fail = time_uptime;
                           return (NULL);
                   }
           }
   #endif
           if (flags & M_WAITOK)
                   KASSERT(curthread->td_intr_nesting_level == 0,
                      ("malloc(M_WAITOK) in interrupt context"));
           KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
               ("malloc: called with spinlock or critical section held"));
   
   #ifdef DEBUG_MEMGUARD
           if (memguard_cmp_mtp(mtp, size)) {
                   va = memguard_alloc(size, flags);
                   if (va != NULL)
                           return (va);
                   /* This is unfortunate but should not be fatal. */
           }
   #endif
   
   #ifdef DEBUG_REDZONE
           size = redzone_size_ntor(size);
   #endif
   
           if (size <= kmem_zmax) {
                   mtip = mtp->ks_handle;
                   if (size & KMEM_ZMASK)
                           size = (size & ~KMEM_ZMASK) + KMEM_ZBASE;
                   indx = kmemsize[size >> KMEM_ZSHIFT];
                   KASSERT(mtip->mti_zone < numzones,
                       ("mti_zone %u out of range %d",
                       mtip->mti_zone, numzones));
                   zone = kmemzones[indx].kz_zone[mtip->mti_zone];
   #ifdef MALLOC_PROFILE
                   krequests[size >> KMEM_ZSHIFT]++;
   #endif
                   va = uma_zalloc(zone, flags);
                   if (va != NULL)
                           size = zone->uz_size;
                   malloc_type_zone_allocated(mtp, va == NULL ? 0 : size, indx);
           } else {
                   size = roundup(size, PAGE_SIZE);
                   zone = NULL;
                   va = uma_large_malloc(size, flags);
                   malloc_type_allocated(mtp, va == NULL ? 0 : size);
           }
           if (flags & M_WAITOK)
                   KASSERT(va != NULL, ("malloc(M_WAITOK) returned NULL"));
           else if (va == NULL)
                   t_malloc_fail = time_uptime;
   #ifdef DIAGNOSTIC
           if (va != NULL && !(flags & M_ZERO)) {
                   memset(va, 0x70, osize);
           }
   #endif
   #ifdef DEBUG_REDZONE
           if (va != NULL)
                   va = redzone_setup(va, osize);
   #endif
           return ((void *) va);
   }
   
   /*
    *      free:
    *
    *      Free a block of memory allocated by malloc.
    *
    *      This routine may not block.
    */
   void
   free(void *addr, struct malloc_type *mtp)
   {
           uma_slab_t slab;
           u_long size;
   
           KASSERT(mtp->ks_magic == M_MAGIC, ("free: bad malloc type magic"));
           KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
               ("free: called with spinlock or critical section held"));
   
           /* free(NULL, ...) does nothing */
           if (addr == NULL)
                   return;
   
   #ifdef DEBUG_MEMGUARD
           if (is_memguard_addr(addr)) {
                   memguard_free(addr);
                   return;
           }
   #endif
   
   #ifdef DEBUG_REDZONE
           redzone_check(addr);
           addr = redzone_addr_ntor(addr);
   #endif
   
           slab = vtoslab((vm_offset_t)addr & (~UMA_SLAB_MASK));
   
           if (slab == NULL)
                   panic("free: address %p(%p) has not been allocated.\n",
                       addr, (void *)((u_long)addr & (~UMA_SLAB_MASK)));
   
           if (!(slab->us_flags & UMA_SLAB_MALLOC)) {
   #ifdef INVARIANTS
                   struct malloc_type **mtpp = addr;
   #endif
                   size = slab->us_keg->uk_size;
   #ifdef INVARIANTS
                   /*
                    * Cache a pointer to the malloc_type that most recently freed
                    * this memory here.  This way we know who is most likely to
                    * have stepped on it later.
                    *
                    * This code assumes that size is a multiple of 8 bytes for
                    * 64 bit machines
                    */
                   mtpp = (struct malloc_type **)
                       ((unsigned long)mtpp & ~UMA_ALIGN_PTR);
                   mtpp += (size - sizeof(struct malloc_type *)) /
                       sizeof(struct malloc_type *);
                   *mtpp = mtp;
   #endif
                   uma_zfree_arg(LIST_FIRST(&slab->us_keg->uk_zones), addr, slab);
           } else {
                   size = slab->us_size;
                   uma_large_free(slab);
           }
           malloc_type_freed(mtp, size);
   }
   
   /*
    *      realloc: change the size of a memory block
    */
   void *
   realloc(void *addr, unsigned long size, struct malloc_type *mtp, int flags)
   {
           uma_slab_t slab;
           unsigned long alloc;
           void *newaddr;
   
           KASSERT(mtp->ks_magic == M_MAGIC,
               ("realloc: bad malloc type magic"));
           KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
               ("realloc: called with spinlock or critical section held"));
   
           /* realloc(NULL, ...) is equivalent to malloc(...) */
           if (addr == NULL)
                   return (malloc(size, mtp, flags));
   
           /*
            * XXX: Should report free of old memory and alloc of new memory to
            * per-CPU stats.
            */
   
   #ifdef DEBUG_MEMGUARD
           if (is_memguard_addr(addr))
                   return (memguard_realloc(addr, size, mtp, flags));
   #endif
   
   #ifdef DEBUG_REDZONE
           slab = NULL;
           alloc = redzone_get_size(addr);
   #else
           slab = vtoslab((vm_offset_t)addr & ~(UMA_SLAB_MASK));
   
           /* Sanity check */
           KASSERT(slab != NULL,
               ("realloc: address %p out of range", (void *)addr));
   
           /* Get the size of the original block */
           if (!(slab->us_flags & UMA_SLAB_MALLOC))
                   alloc = slab->us_keg->uk_size;
           else
                   alloc = slab->us_size;
   
           /* Reuse the original block if appropriate */
           if (size <= alloc
               && (size > (alloc >> REALLOC_FRACTION) || alloc == MINALLOCSIZE))
                   return (addr);
   #endif /* !DEBUG_REDZONE */
   
           /* Allocate a new, bigger (or smaller) block */
           if ((newaddr = malloc(size, mtp, flags)) == NULL)
                   return (NULL);
   
           /* Copy over original contents */
           bcopy(addr, newaddr, min(size, alloc));
           free(addr, mtp);
           return (newaddr);
   }
   
   /*
    *      reallocf: same as realloc() but free memory on failure.
    */
   void *
   reallocf(void *addr, unsigned long size, struct malloc_type *mtp, int flags)
   {
           void *mem;
   
           if ((mem = realloc(addr, size, mtp, flags)) == NULL)
                   free(addr, mtp);
           return (mem);
   }
   
   /*
    * Wake the uma reclamation pagedaemon thread when we exhaust KVA.  It
    * will call the lowmem handler and uma_reclaim() callbacks in a
    * context that is safe.
    */
   static void
   kmem_reclaim(vmem_t *vm, int flags)
   {
   
           uma_reclaim_wakeup();
           pagedaemon_wakeup();
   }
   
   #ifndef __sparc64__
   CTASSERT(VM_KMEM_SIZE_SCALE >= 1);
   #endif
   
   /*
    * Initialize the kernel memory (kmem) arena.
    */
   void
   kmeminit(void)
   {
           u_long mem_size;
           u_long tmp;
   
   #ifdef VM_KMEM_SIZE
           if (vm_kmem_size == 0)
                   vm_kmem_size = VM_KMEM_SIZE;
   #endif
   #ifdef VM_KMEM_SIZE_MIN
           if (vm_kmem_size_min == 0)
                   vm_kmem_size_min = VM_KMEM_SIZE_MIN;
   #endif
   #ifdef VM_KMEM_SIZE_MAX
           if (vm_kmem_size_max == 0)
                   vm_kmem_size_max = VM_KMEM_SIZE_MAX;
   #endif
           /*
            * Calculate the amount of kernel virtual address (KVA) space that is
            * preallocated to the kmem arena.  In order to support a wide range
            * of machines, it is a function of the physical memory size,
            * specifically,
            *
            *      min(max(physical memory size / VM_KMEM_SIZE_SCALE,
            *          VM_KMEM_SIZE_MIN), VM_KMEM_SIZE_MAX)
            *
            * Every architecture must define an integral value for
            * VM_KMEM_SIZE_SCALE.  However, the definitions of VM_KMEM_SIZE_MIN
            * and VM_KMEM_SIZE_MAX, which represent respectively the floor and
            * ceiling on this preallocation, are optional.  Typically,
            * VM_KMEM_SIZE_MAX is itself a function of the available KVA space on
            * a given architecture.
            */
           mem_size = vm_cnt.v_page_count;
           if (mem_size <= 32768) /* delphij XXX 128MB */
                   kmem_zmax = PAGE_SIZE;
   
           if (vm_kmem_size_scale < 1)
                   vm_kmem_size_scale = VM_KMEM_SIZE_SCALE;
   
           /*
            * Check if we should use defaults for the "vm_kmem_size"
            * variable:
            */
           if (vm_kmem_size == 0) {
                   vm_kmem_size = (mem_size / vm_kmem_size_scale) * PAGE_SIZE;
   
                   if (vm_kmem_size_min > 0 && vm_kmem_size < vm_kmem_size_min)
                           vm_kmem_size = vm_kmem_size_min;
                   if (vm_kmem_size_max > 0 && vm_kmem_size >= vm_kmem_size_max)
                           vm_kmem_size = vm_kmem_size_max;
           }
   
           /*
            * The amount of KVA space that is preallocated to the
            * kmem arena can be set statically at compile-time or manually
            * through the kernel environment.  However, it is still limited to
            * twice the physical memory size, which has been sufficient to handle
            * the most severe cases of external fragmentation in the kmem arena. 
            */
           if (vm_kmem_size / 2 / PAGE_SIZE > mem_size)
                   vm_kmem_size = 2 * mem_size * PAGE_SIZE;
   
           vm_kmem_size = round_page(vm_kmem_size);
   #ifdef DEBUG_MEMGUARD
           tmp = memguard_fudge(vm_kmem_size, kernel_map);
   #else
           tmp = vm_kmem_size;
   #endif
           vmem_init(kmem_arena, "kmem arena", kva_alloc(tmp), tmp, PAGE_SIZE,
               0, 0);
           vmem_set_reclaim(kmem_arena, kmem_reclaim);
   
   #ifdef DEBUG_MEMGUARD
           /*
            * Initialize MemGuard if support compiled in.  MemGuard is a
            * replacement allocator used for detecting tamper-after-free
            * scenarios as they occur.  It is only used for debugging.
            */
           memguard_init(kmem_arena);
   #endif
   }
   
   /*
    * Initialize the kernel memory allocator
    */
   /* ARGSUSED*/
   static void
   mallocinit(void *dummy)
   {
           int i;
           uint8_t indx;
   
           mtx_init(&malloc_mtx, "malloc", NULL, MTX_DEF);
   
           kmeminit();
   
           uma_startup2();
   
           if (kmem_zmax < PAGE_SIZE || kmem_zmax > KMEM_ZMAX)
                   kmem_zmax = KMEM_ZMAX;
   
           mt_zone = uma_zcreate("mt_zone", sizeof(struct malloc_type_internal),
   #ifdef INVARIANTS
               mtrash_ctor, mtrash_dtor, mtrash_init, mtrash_fini,
   #else
               NULL, NULL, NULL, NULL,
   #endif
               UMA_ALIGN_PTR, UMA_ZONE_MALLOC);
           for (i = 0, indx = 0; kmemzones[indx].kz_size != 0; indx++) {
                   int size = kmemzones[indx].kz_size;
                   char *name = kmemzones[indx].kz_name;
                   int subzone;
   
                   for (subzone = 0; subzone < numzones; subzone++) {
                           kmemzones[indx].kz_zone[subzone] =
                               uma_zcreate(name, size,
   #ifdef INVARIANTS
                               mtrash_ctor, mtrash_dtor, mtrash_init, mtrash_fini,
   #else
                               NULL, NULL, NULL, NULL,
   #endif
                               UMA_ALIGN_PTR, UMA_ZONE_MALLOC);
                   }                   
                   for (;i <= size; i+= KMEM_ZBASE)
                           kmemsize[i >> KMEM_ZSHIFT] = indx;
   
           }
   }
   SYSINIT(kmem, SI_SUB_KMEM, SI_ORDER_SECOND, mallocinit, NULL);
   
   void
   malloc_init(void *data)
   {
           struct malloc_type_internal *mtip;
           struct malloc_type *mtp;
   
           KASSERT(vm_cnt.v_page_count != 0, ("malloc_register before vm_init"));
   
           mtp = data;
           if (mtp->ks_magic != M_MAGIC)
                   panic("malloc_init: bad malloc type magic");
   
           mtip = uma_zalloc(mt_zone, M_WAITOK | M_ZERO);
           mtp->ks_handle = mtip;
           mtip->mti_zone = mtp_get_subzone(mtp->ks_shortdesc);
   
           mtx_lock(&malloc_mtx);
           mtp->ks_next = kmemstatistics;
           kmemstatistics = mtp;
           kmemcount++;
           mtx_unlock(&malloc_mtx);
   }
   
   void
   malloc_uninit(void *data)
   {
           struct malloc_type_internal *mtip;
           struct malloc_type_stats *mtsp;
           struct malloc_type *mtp, *temp;
           uma_slab_t slab;
           long temp_allocs, temp_bytes;
           int i;
   
           mtp = data;
           KASSERT(mtp->ks_magic == M_MAGIC,
               ("malloc_uninit: bad malloc type magic"));
           KASSERT(mtp->ks_handle != NULL, ("malloc_deregister: cookie NULL"));
   
           mtx_lock(&malloc_mtx);
           mtip = mtp->ks_handle;
           mtp->ks_handle = NULL;
           if (mtp != kmemstatistics) {
                   for (temp = kmemstatistics; temp != NULL;
                       temp = temp->ks_next) {
                           if (temp->ks_next == mtp) {
                                   temp->ks_next = mtp->ks_next;
                                   break;
                           }
                   }
                   KASSERT(temp,
                       ("malloc_uninit: type '%s' not found", mtp->ks_shortdesc));
           } else
                   kmemstatistics = mtp->ks_next;
           kmemcount--;
           mtx_unlock(&malloc_mtx);
   
           /*
            * Look for memory leaks.
            */
           temp_allocs = temp_bytes = 0;
           for (i = 0; i < MAXCPU; i++) {
                   mtsp = &mtip->mti_stats[i];
                   temp_allocs += mtsp->mts_numallocs;
                   temp_allocs -= mtsp->mts_numfrees;
                   temp_bytes += mtsp->mts_memalloced;
                   temp_bytes -= mtsp->mts_memfreed;
           }
           if (temp_allocs > 0 || temp_bytes > 0) {
                   printf("Warning: memory type %s leaked memory on destroy "
                       "(%ld allocations, %ld bytes leaked).\n", mtp->ks_shortdesc,
                       temp_allocs, temp_bytes);
           }
   
           slab = vtoslab((vm_offset_t) mtip & (~UMA_SLAB_MASK));
           uma_zfree_arg(mt_zone, mtip, slab);
   }
   
   struct malloc_type *
   malloc_desc2type(const char *desc)
   {
           struct malloc_type *mtp;
   
           mtx_assert(&malloc_mtx, MA_OWNED);
           for (mtp = kmemstatistics; mtp != NULL; mtp = mtp->ks_next) {
                   if (strcmp(mtp->ks_shortdesc, desc) == 0)
                           return (mtp);
           }
           return (NULL);
   }
   
   static int
   sysctl_kern_malloc_stats(SYSCTL_HANDLER_ARGS)
   {
           struct malloc_type_stream_header mtsh;
           struct malloc_type_internal *mtip;
           struct malloc_type_header mth;
           struct malloc_type *mtp;
           int error, i;
           struct sbuf sbuf;
   
           error = sysctl_wire_old_buffer(req, 0);
           if (error != 0)
                   return (error);
           sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
           sbuf_clear_flags(&sbuf, SBUF_INCLUDENUL);
           mtx_lock(&malloc_mtx);
   
           /*
            * Insert stream header.
            */
           bzero(&mtsh, sizeof(mtsh));
           mtsh.mtsh_version = MALLOC_TYPE_STREAM_VERSION;
           mtsh.mtsh_maxcpus = MAXCPU;
           mtsh.mtsh_count = kmemcount;
           (void)sbuf_bcat(&sbuf, &mtsh, sizeof(mtsh));
   
           /*
            * Insert alternating sequence of type headers and type statistics.
            */
           for (mtp = kmemstatistics; mtp != NULL; mtp = mtp->ks_next) {
                   mtip = (struct malloc_type_internal *)mtp->ks_handle;
   
                   /*
                    * Insert type header.
                    */
                   bzero(&mth, sizeof(mth));
                   strlcpy(mth.mth_name, mtp->ks_shortdesc, MALLOC_MAX_NAME);
                   (void)sbuf_bcat(&sbuf, &mth, sizeof(mth));
   
                   /*
                    * Insert type statistics for each CPU.
                    */
                   for (i = 0; i < MAXCPU; i++) {
                           (void)sbuf_bcat(&sbuf, &mtip->mti_stats[i],
                               sizeof(mtip->mti_stats[i]));
                   }
           }
           mtx_unlock(&malloc_mtx);
           error = sbuf_finish(&sbuf);
           sbuf_delete(&sbuf);
           return (error);
   }
   
   SYSCTL_PROC(_kern, OID_AUTO, malloc_stats, CTLFLAG_RD|CTLTYPE_STRUCT,
       0, 0, sysctl_kern_malloc_stats, "s,malloc_type_ustats",
       "Return malloc types");
   
   SYSCTL_INT(_kern, OID_AUTO, malloc_count, CTLFLAG_RD, &kmemcount, 0,
       "Count of kernel malloc types");
   
   void
   malloc_type_list(malloc_type_list_func_t *func, void *arg)
   {
           struct malloc_type *mtp, **bufmtp;
           int count, i;
           size_t buflen;
   
           mtx_lock(&malloc_mtx);
   restart:
           mtx_assert(&malloc_mtx, MA_OWNED);
           count = kmemcount;
           mtx_unlock(&malloc_mtx);
   
           buflen = sizeof(struct malloc_type *) * count;
           bufmtp = malloc(buflen, M_TEMP, M_WAITOK);
   
           mtx_lock(&malloc_mtx);
   
           if (count < kmemcount) {
                   free(bufmtp, M_TEMP);
                   goto restart;
           }
   
           for (mtp = kmemstatistics, i = 0; mtp != NULL; mtp = mtp->ks_next, i++)
                   bufmtp[i] = mtp;
   
           mtx_unlock(&malloc_mtx);
   
          for (i = 0; i < count; i++)
                  (func)(bufmtp[i], arg);
  
          free(bufmtp, M_TEMP);
  }
  
  #ifdef DDB
  DB_SHOW_COMMAND(malloc, db_show_malloc)
  {
          struct malloc_type_internal *mtip;
          struct malloc_type *mtp;
          uint64_t allocs, frees;
          uint64_t alloced, freed;
          int i;
  
          db_printf("%18s %12s  %12s %12s\n", "Type", "InUse", "MemUse",
              "Requests");
          for (mtp = kmemstatistics; mtp != NULL; mtp = mtp->ks_next) {
                  mtip = (struct malloc_type_internal *)mtp->ks_handle;
                  allocs = 0;
                  frees = 0;
                  alloced = 0;
                  freed = 0;
                  for (i = 0; i < MAXCPU; i++) {
                          allocs += mtip->mti_stats[i].mts_numallocs;
                          frees += mtip->mti_stats[i].mts_numfrees;
                          alloced += mtip->mti_stats[i].mts_memalloced;
                          freed += mtip->mti_stats[i].mts_memfreed;
                  }
                  db_printf("%18s %12ju %12juK %12ju\n",
                      mtp->ks_shortdesc, allocs - frees,
                      (alloced - freed + 1023) / 1024, allocs);
                  if (db_pager_quit)
                          break;
          }
  }
  
  #if MALLOC_DEBUG_MAXZONES > 1
  DB_SHOW_COMMAND(multizone_matches, db_show_multizone_matches)
  {
          struct malloc_type_internal *mtip;
          struct malloc_type *mtp;
          u_int subzone;
  
          if (!have_addr) {
                  db_printf("Usage: show multizone_matches <malloc type/addr>\n");
                  return;
          }
          mtp = (void *)addr;
          if (mtp->ks_magic != M_MAGIC) {
                  db_printf("Magic %lx does not match expected %x\n",
                      mtp->ks_magic, M_MAGIC);
                  return;
          }
  
          mtip = mtp->ks_handle;
          subzone = mtip->mti_zone;
  
          for (mtp = kmemstatistics; mtp != NULL; mtp = mtp->ks_next) {
                  mtip = mtp->ks_handle;
                  if (mtip->mti_zone != subzone)
                          continue;
                  db_printf("%s\n", mtp->ks_shortdesc);
                  if (db_pager_quit)
                          break;
          }
  }
  #endif /* MALLOC_DEBUG_MAXZONES > 1 */
  #endif /* DDB */
  
  #ifdef MALLOC_PROFILE
  
  static int
  sysctl_kern_mprof(SYSCTL_HANDLER_ARGS)
  {
          struct sbuf sbuf;
          uint64_t count;
          uint64_t waste;
          uint64_t mem;
          int error;
          int rsize;
          int size;
          int i;
  
          waste = 0;
          mem = 0;
  
          error = sysctl_wire_old_buffer(req, 0);
          if (error != 0)
                  return (error);
          sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
          sbuf_printf(&sbuf, 
              "\n  Size                    Requests  Real Size\n");
          for (i = 0; i < KMEM_ZSIZE; i++) {
                  size = i << KMEM_ZSHIFT;
                  rsize = kmemzones[kmemsize[i]].kz_size;
                  count = (long long unsigned)krequests[i];
  
                  sbuf_printf(&sbuf, "%6d%28llu%11d\n", size,
                      (unsigned long long)count, rsize);
  
                  if ((rsize * count) > (size * count))
                          waste += (rsize * count) - (size * count);
                  mem += (rsize * count);
          }
          sbuf_printf(&sbuf,
              "\nTotal memory used:\t%30llu\nTotal Memory wasted:\t%30llu\n",
              (unsigned long long)mem, (unsigned long long)waste);
          error = sbuf_finish(&sbuf);
          sbuf_delete(&sbuf);
          return (error);
  }
  
  SYSCTL_OID(_kern, OID_AUTO, mprof, CTLTYPE_STRING|CTLFLAG_RD,
      NULL, 0, sysctl_kern_mprof, "A", "Malloc Profiling");
  #endif /* MALLOC_PROFILE */

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