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.\" .\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. 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(s), this list of conditions and the following disclaimer as .\" the first lines of this file unmodified other than the possible .\" addition of one or more copyright notices. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice(s), this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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. .\" .\" $FreeBSD: release/9.1.0/share/man/man9/vm_page_alloc.9 209669 2010-07-03 18:25:37Z alc $ .\" .Dd July 3, 2010 .Dt VM_PAGE_ALLOC 9 .Os .Sh NAME .Nm vm_page_alloc .Nd "allocate a page for a" .Vt vm_object .Sh SYNOPSIS .In sys/param.h .In vm/vm.h .In vm/vm_page.h .Ft vm_page_t .Fn vm_page_alloc "vm_object_t object" "vm_pindex_t pindex" "int req" .Sh DESCRIPTION The .Fn vm_page_alloc function allocates a page at .Fa pindex within .Fa object . It is assumed that a page has not already been allocated at .Fa pindex . The page returned is inserted into the object, unless .Dv VM_ALLOC_NOOBJ is specified in the .Fa req . The page may exist in the vm object cache, in which case it will be reactivated instead, moving from the cache into the object page list. .Pp .Fn vm_page_alloc will not sleep. .Pp Its arguments are: .Bl -tag -width ".Fa object" .It Fa object The VM object to allocate the page for. The .Fa object must be locked if .Dv VM_ALLOC_NOOBJ is not specified. .It Fa pindex The index into the object at which the page should be inserted. .It Fa req The bitwise-inclusive OR of a class and any optional flags indicating how the page should be allocated. .Pp Exactly one of the following classes must be specified: .Bl -tag -width ".Dv VM_ALLOC_INTERRUPT" .It Dv VM_ALLOC_NORMAL The page should be allocated with no special treatment. .It Dv VM_ALLOC_SYSTEM The page can be allocated if the cache is empty and the free page count is above the interrupt reserved water mark. This flag should be used only when the system really needs the page. .It Dv VM_ALLOC_INTERRUPT .Fn vm_page_alloc is being called during an interrupt. A page will be returned successfully if the free page count is greater than zero. .El .Pp The optional flags are: .Bl -tag -width ".Dv VM_ALLOC_IFNOTCACHED" .It Dv VM_ALLOC_ZERO Indicate a preference for a pre-zeroed page. There is no guarantee that the returned page will be zeroed, but it will have the .Dv PG_ZERO flag set if it is zeroed. .It Dv VM_ALLOC_NOOBJ Do not associate the allocated page with a vm object. The .Fa object argument is ignored. .It Dv VM_ALLOC_NOBUSY The returned page will not have the .Dv VPO_BUSY flag set. .It Dv VM_ALLOC_WIRED The returned page will be wired. .It Dv VM_ALLOC_IFCACHED Allocate the page only if it is cached. Otherwise, return .Dv NULL . .It Dv VM_ALLOC_IFNOTCACHED Only allocate the page if it is not cached in the .Fa object . If the page at the specified .Fa pindex is cached, NULL is returned instead. .El .El .Sh RETURN VALUES The .Vt vm_page_t that was allocated is returned if successful; otherwise, .Dv NULL is returned. .Sh NOTES The pager process is always upgraded to .Dv VM_ALLOC_SYSTEM unless .Dv VM_ALLOC_INTERRUPT is set. .Sh AUTHORS This manual page was written by .An Chad David Aq davidc@acns.ab.ca .