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263 lines
8.9 KiB
Groff
263 lines
8.9 KiB
Groff
.\" $NetBSD: malloc.9,v 1.3 1996/11/11 00:05:11 lukem Exp $
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.\"
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.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Paul Kranenburg.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd June 16, 1996
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.Dt MALLOC 9
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.Os FreeBSD
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.Sh NAME
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.Nm malloc ,
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.Nm MALLOC ,
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.Nm free ,
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.Nm FREE
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.Nd kernel memory management routines
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.Sh SYNOPSIS
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.Ft void *
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.Fn malloc "unsigned long size" "int type" "int flags"
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.Fn MALLOC "space" "cast" "unsigned long size" "int type" "int flags"
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.Ft void
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.Fn free "void *addr" "int type"
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.Fn FREE "void *addr" "int type"
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.Sh DESCRIPTION
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The
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.Fn malloc
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function allocates uninitialized memory in kernel address space for an
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object whose size is specified by
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.Fa size .
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.Fn free
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releases memory at address
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.Fa addr
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that was previously allocated by
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.Fn malloc
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for re-use.
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The
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.Fn MALLOC
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macro variant is functionally equivalent to
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.Bd -literal -offset indent
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(space) = (cast)malloc((u_long)(size), type, flags)
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.Ed
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.Pp
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and the
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.Fn FREE
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macro variant is equivalent to
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.Bd -literal -offset indent
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free((addr), type)
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.Ed
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.Pp
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Unlike its standard C library counterpart
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.Pq Xr malloc 3 ,
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the kernel version takes two more arguments. The
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.Fa flags
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argument further qualifies
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.Fn malloc No Ns 's
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operational characteristics as follows:
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.Bl -tag -offset indent
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.It Dv M_NOWAIT
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Causes
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.Fn malloc
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to return
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.Dv NULL
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if the request cannot be immediately fulfilled due to resource shortage.
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Otherwise,
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.Fn malloc
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may call sleep to wait for resources to be released by other processes.
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If this flag is not set,
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.Fn malloc
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will never return
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.Dv NULL .
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Note that
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.Dv M_WAITOK
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is conveniently defined to be 0, and hence maybe or'ed into the
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.Fa flags
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argument to indicate that it's Ok to wait for resources.
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.El
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.Pp
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Currently, only one flag is defined.
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.Pp
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The
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.Fa type
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argument broadly identifies the kernel subsystem for which the allocated
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memory was needed, and is commonly used to maintain statistics about
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kernel memory usage. The following types are currently defined in
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the header file
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.Aq Pa sys/malloc.h :
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.Pp
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.Bd -literal
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#define M_FREE 0 /* should be on free list */
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#define M_MBUF 1 /* mbuf */
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#define M_DEVBUF 2 /* device driver memory */
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#define M_SOCKET 3 /* socket structure */
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#define M_PCB 4 /* protocol control block */
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#define M_RTABLE 5 /* routing tables */
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#define M_HTABLE 6 /* IMP host tables */
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#define M_FTABLE 7 /* fragment reassembly header */
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#define M_ZOMBIE 8 /* zombie proc status */
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#define M_IFADDR 9 /* interface address */
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#define M_SOOPTS 10 /* socket options */
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#define M_SONAME 11 /* socket name */
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#define M_NAMEI 12 /* namei path name buffer */
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#define M_GPROF 13 /* kernel profiling buffer */
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#define M_IOCTLOPS 14 /* ioctl data buffer */
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#define M_MAPMEM 15 /* mapped memory descriptors */
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#define M_CRED 16 /* credentials */
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#define M_PGRP 17 /* process group header */
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#define M_SESSION 18 /* session header */
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#define M_IOV 19 /* large iov's */
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#define M_MOUNT 20 /* vfs mount struct */
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#define M_FHANDLE 21 /* network file handle */
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#define M_NFSREQ 22 /* NFS request header */
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#define M_NFSMNT 23 /* NFS mount structure */
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#define M_NFSNODE 24 /* NFS vnode private part */
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#define M_VNODE 25 /* Dynamically allocated vnodes */
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#define M_CACHE 26 /* Dynamically allocated cache entries */
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#define M_DQUOT 27 /* UFS quota entries */
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#define M_UFSMNT 28 /* UFS mount structure */
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#define M_SHM 29 /* SVID compatible shared memory segments */
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#define M_VMMAP 30 /* VM map structures */
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#define M_VMMAPENT 31 /* VM map entry structures */
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#define M_VMOBJ 32 /* VM object structure */
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#define M_VMOBJHASH 33 /* VM object hash structure */
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#define M_VMPMAP 34 /* VM pmap */
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#define M_VMPVENT 35 /* VM phys-virt mapping entry */
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#define M_VMPAGER 36 /* XXX: VM pager struct */
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#define M_VMPGDATA 37 /* XXX: VM pager private data */
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#define M_FILE 38 /* Open file structure */
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#define M_FILEDESC 39 /* Open file descriptor table */
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#define M_LOCKF 40 /* Byte-range locking structures */
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#define M_PROC 41 /* Proc structures */
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#define M_SUBPROC 42 /* Proc sub-structures */
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#define M_SEGMENT 43 /* Segment for LFS */
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#define M_LFSNODE 44 /* LFS vnode private part */
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#define M_FFSNODE 45 /* FFS vnode private part */
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#define M_MFSNODE 46 /* MFS vnode private part */
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#define M_NQLEASE 47 /* Nqnfs lease */
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#define M_NQMHOST 48 /* Nqnfs host address table */
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#define M_NETADDR 49 /* Export host address structure */
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#define M_NFSSVC 50 /* Nfs server structure */
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#define M_NFSUID 51 /* Nfs uid mapping structure */
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#define M_NFSD 52 /* Nfs server daemon structure */
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#define M_IPMOPTS 53 /* internet multicast options */
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#define M_IPMADDR 54 /* internet multicast address */
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#define M_IFMADDR 55 /* link-level multicast address */
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#define M_MRTABLE 56 /* multicast routing tables */
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#define M_ISOFSMNT 57 /* ISOFS mount structure */
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#define M_ISOFSNODE 58 /* ISOFS vnode private part */
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#define M_NFSRVDESC 59 /* NFS server socket descriptor */
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#define M_NFSDIROFF 60 /* NFS directory offset data */
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#define M_NFSBIGFH 61 /* NFS version 3 file handle */
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#define M_MSDOSFSMNT 67 /* MSDOSFS mount structure */
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#define M_MSDOSFSNODE 68 /* MSDOSFS vnode private part */
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#define M_MSDOSFSFAT 69 /* MSDOSFS file allocation table */
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#define M_DEVFSMNT 70 /* DEVFS mount structure */
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#define M_DEVFSBACK 71 /* DEVFS Back node */
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#define M_DEVFSFRONT 72 /* DEVFS Front node */
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#define M_DEVFSNODE 73 /* DEVFS node */
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#define M_TEMP 74 /* misc temporary data buffers */
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#define M_TTYS 75 /* tty data structures */
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#define M_GZIP 76 /* Gzip trees */
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#define M_IPFW 77 /* IpFw/IpAcct chain's */
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#define M_DEVL 78 /* isa_device lists in userconfig() */
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#define M_PKTCLASS 79 /* structures used in packet classifier */
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#define M_SYSCTL 80 /* sysctl internal magic */
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#define M_SECA 81 /* security associations, key management */
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#define M_BIOBUF 82 /* BIO buffer */
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#define M_KTRACE 83 /* KTRACE */
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#define M_SELECT 84 /* select() buffer */
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#define M_GEOM_DEV 85 /* geometry device */
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#define M_GEOM_MOD 86 /* geometry module */
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#define M_GEOM_REQ 87 /* geometry request */
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#define M_GEOM_MISC 88 /* geometry misc */
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#define M_VFSCONF 89 /* vfsconf structure */
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.Ed
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.Pp
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Statistics based on the
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.Fa type
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argument are maintained only if the kernel option
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.Dv KMEMSTATS
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is used when compiling the kernel
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(the default in
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.Tn FreeBSD
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kernels)
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and can be examined by using
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.Sq vmstat -m .
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.Sh RETURN VALUES
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.Fn malloc
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returns a kernel virtual address that is suitably aligned for storage of
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any type of object.
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.Sh SEE ALSO
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.Xr vmstat 8
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.Sh DIAGNOSTICS
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A kernel compiled with the
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.Dv DIAGNOSTIC
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configuration option attempts to detect detect memory corruption caused by
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such things as writing outside the allocated area and imbalanced calls to the
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.Fn malloc
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and
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.Fn free
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functions. Failing consistency checks will cause a panic or a system console
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message:
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.Bl -bullet -offset indent -compact
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.Pp
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.It
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panic:
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.Dq malloc: bogus type
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.It
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panic:
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.Dq malloc: allocation too large
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.It
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panic:
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.Dq malloc: wrong bucket
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.It
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panic:
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.Dq malloc: lost data
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.It
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panic:
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.Dq free: address 0x%x out of range
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.It
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panic:
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.Dq free: type %d out of range
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.It
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panic:
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.Dq free: unaligned addr Aq description of object
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.It
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panic:
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.Dq free: item modified
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.It
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panic:
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.Dq free: multiple free[s]
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.It
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.Dq Data modified on freelist: Aq description of object
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.El
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