VM_PAGE_ALLOC(9) BSD Kernel Developer's Manual VM_PAGE_ALLOC(9)NAMEvm_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 page_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, but is not inserted into the
pmap. The vm_object must be locked on entry.
vm_page_alloc() will not block.
Its arguments are:
object The VM object to allocate the page for.
pindex The index into the object at which the page should be inserted.
page_req A flag indicating how the page should be allocated.
VM_ALLOC_NORMAL The page should be allocated with no spe‐
cial treatment.
VM_ALLOC_QUICK The page should only be allocated from the
free queue.
VM_ALLOC_SYSTEM The page can be allocated if the cache
queue is empty and the free page count is
above the interrupt reserved water mark.
If VM_ALLOC_INTERRUPT is set, the page can
be allocated as long as the free page count
is greater than zero. This flag should be
used only when the system really needs the
page.
VM_ALLOC_INTERRUPT vm_page_alloc() is being called during an
interrupt and therefore the cache cannot be
accessed. The page will only be returned
successfully if the free count is greater
than zero.
VM_ALLOC_ZERO Indicate a preference for a pre-zeroed
page. There is no guarantee that the page
thus returned will be zeroed, but it will
be marked as such.
RETURN VALUES
The vm_page_t that was allocated is returned if successful; otherwise,
NULL is returned. The returned page will be marked PG_BUSY.
AUTHORS
This manual page was written by Chad David ⟨davidc@acns.ab.ca⟩.
BSD December 19, 2010 BSD
