1.\" 2.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" Copyright (c) 2013 The FreeBSD Foundation 4.\" 5.\" Portions of this documentation were written by Konstantin Belousov 6.\" under sponsorship from the FreeBSD Foundation. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice(s), this list of conditions and the following disclaimer as 13.\" the first lines of this file unmodified other than the possible 14.\" addition of one or more copyright notices. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice(s), this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 20.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 21.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 22.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 23.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 24.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 25.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 26.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 29.\" DAMAGE. 30.\" 31.\" $FreeBSD$ 32.\" 33.Dd August 23, 2013 34.Dt VM_PAGE_GRAB 9 35.Os 36.Sh NAME 37.Nm vm_page_grab 38.Nd "returns a page from an object" 39.Sh SYNOPSIS 40.In sys/param.h 41.In vm/vm.h 42.In vm/vm_page.h 43.Ft vm_page_t 44.Fn vm_page_grab "vm_object_t object" "vm_pindex_t pindex" "int allocflags" 45.Sh DESCRIPTION 46The 47.Fn vm_page_grab 48function returns the page at 49.Fa pindex 50from the given object. 51If the page exists and is busy, 52.Fn vm_page_grab 53will sleep while waiting for it. 54If the page does not exist, it is allocated. 55The function sleeps until the allocation request can be satisfied. 56.Pp 57The function requires the 58.Fa object 59to be locked on entry, and returns with the object locked. 60If the 61.Fn vm_page_grab 62function sleeps for any reason, the object lock is temporary dropped. 63.Pp 64The 65.Fn vm_page_grab 66supports all of the flags supported by 67.Xr vm_page_alloc 9 . 68In addition, 69.Fn vm_page_grab 70supports the following flags: 71.Bl -tag -width ".Dv VM_ALLOC_IGN_SBUSY" 72.It Dv VM_ALLOC_IGN_SBUSY 73When waiting for the busy state of the existing page to drain, 74only test for exclusive busy; ignore the shared busy counter. 75.El 76.Sh RETURN VALUES 77The 78.Fn vm_page_grab 79always returns the page. 80.Sh SEE ALSO 81.Xr vm_page_alloc 9 82.Sh AUTHORS 83This manual page was written by 84.An Chad David Aq Mt davidc@acns.ab.ca . 85