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VM_PAGE_ALLOC(9)	 BSD Kernel Developer's	Manual	      VM_PAGE_ALLOC(9)

NAME
     vm_page_alloc -- allocate a page for a vm_object

SYNOPSIS
     #include <sys/param.h>
     #include <vm/vm.h>
     #include <vm/vm_page.h>

     vm_page_t
     vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req);

DESCRIPTION
     The vm_page_alloc() function allocates a page at pindex within object.
     It	is assumed that	a page has not already been allocated at pindex.  The
     page returned is inserted into the	object,	unless VM_ALLOC_NOOBJ is spec-
     ified in the req.	The page may exist in the vm object cache, in which
     case it will be reactivated instead, moving from the cache	into the ob-
     ject page list.

     vm_page_alloc() will not sleep.

     Its arguments are:

     object  The VM object to allocate the page	for.  The object must be
	     locked if VM_ALLOC_NOOBJ is not specified.

     pindex  The index into the	object at which	the page should	be inserted.

     req     The bitwise-inclusive OR of a class and any optional flags	indi-
	     cating how	the page should	be allocated.

	     Exactly one of the	following classes must be specified:

	     VM_ALLOC_NORMAL	 The page should be allocated with no special
				 treatment.

	     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.

	     VM_ALLOC_INTERRUPT	 vm_page_alloc() is being called during	an in-
				 terrupt.  A page will be returned success-
				 fully if the free page	count is greater than
				 zero.

	     The optional flags	are:

	     VM_ALLOC_NOBUSY	   The returned	page will not be exclusive
				   busy.

	     VM_ALLOC_NODUMP	   The returned	page will not be included in
				   any kernel core dumps regardless of whether
				   or not it is	mapped in to KVA.

	     VM_ALLOC_NOOBJ	   Do not associate the	allocated page with a
				   vm object.  The object argument is ignored.

	     VM_ALLOC_IFCACHED	   Allocate the	page only if it	is cached.
				   Otherwise, return NULL.

	     VM_ALLOC_IFNOTCACHED  Only	allocate the page if it	is not cached
				   in the object.  If the page at the speci-
				   fied	pindex is cached, NULL is returned in-
				   stead.

	     VM_ALLOC_SBUSY	   The returned	page will be shared busy.

	     VM_ALLOC_WIRED	   The returned	page will be wired.

	     VM_ALLOC_ZERO	   Indicate a preference for a pre-zeroed
				   page.  There	is no guarantee	that the re-
				   turned page will be zeroed, but it will
				   have	the PG_ZERO flag set if	it is zeroed.

RETURN VALUES
     The vm_page_t that	was allocated is returned if successful; otherwise,
     NULL is returned.

NOTES
     The pager process is always upgraded to VM_ALLOC_SYSTEM unless
     VM_ALLOC_INTERRUPT	is set.

AUTHORS
     This manual page was written by Chad David	<davidc@acns.ab.ca>.

BSD			       January 28, 2012				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | NOTES | AUTHORS

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