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.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
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.\" $FreeBSD: src/share/man/man9/vm_page_free.9,v 1.2.36.1.6.1 2010/12/21 17:09:25 kensmith Exp $
.\"
.Dd July 24, 2001
.Dt VM_PAGE_FREE 9
.Os
.Sh NAME
.Nm vm_page_free ,
.Nm vm_page_free_toq ,
.Nm vm_page_free_zero ,
.Nm vm_page_try_to_free
.Nd "free a page"
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/vm_page.h
.Ft void
.Fn vm_page_free "vm_page_t m"
.Ft void
.Fn vm_page_free_toq "vm_page_t m"
.Ft void
.Fn vm_page_free_zero "vm_page_t m"
.Ft int
.Fn vm_page_try_to_free "vm_page_t m"
.Sh DESCRIPTION
The
.Fn vm_page_free_toq
function moves a page into the free queue, and disassociates it from
its object.
If the page is held, wired, already free, or its busy count is not
zero, the system will panic.
If the
.Dv PG_ZERO
flag is set on the page, it is placed at the end of the free queue;
otherwise, it is placed at the front.
.Pp
If the page's object is of type
.Dv OBJT_VNODE
and it is the last page associated with the object, the underlying
vnode may be freed.
.Pp
The
.Fn vm_page_free
and
.Fn vm_page_free_zero
functions both call
.Fn vm_page_free_toq
to actually free the page, but
.Fn vm_page_free_zero
sets the
.Dv PG_ZERO
flag and
.Fn vm_page_free
clears the
.Dv PG_ZERO
flag prior to the call to
.Fn vm_page_free_toq .
.Pp
The
.Fn vm_page_try_to_free
function verifies that the page is not held, wired, busy or dirty, and
if so, marks the page as busy, drops any protection that may be set on
the page, and frees it.
.Sh RETURN VALUES
.Fn vm_page_try_to_free
returns 1 if it is able to free the page; otherwise, 0 is returned.
.Sh SEE ALSO
.Xr vm_page_busy 9 ,
.Xr vm_page_hold 9 ,
.Xr vm_page_wire 9
.Sh AUTHORS
This manual page was written by
.An Chad David Aq davidc@acns.ab.ca .