vm_page_hold(9)

NAME

vm_page_hold, vm_page_unhold - update a page's hold count

#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
void
vm_page_hold(vm_page_t m);
void
vm_page_unhold(vm_page_t m);

The vm_page_hold() function increases the hold count on a
page. This prevents the page daemon from freeing the page.
vm_page_hold() should only be used for very temporary wiring
of a page, as that page will not be considered for paging or realloca
tion for as long as its hold count is greater than zero. Also note that
while wired pages are removed from whatever queue they are on,
vm_page_hold() does
not affect the location of the page. If it is on a queue
prior to the call, it will still be there afterward.
If the page needs to be held for a long period of time,
vm_page_wire(9) should be used.
vm_page_unhold() function reduces the hold count on a page.
If the hold count is zero it is possible that the page will be freed by
the page daemon.