freebsd man page for vm_page_aflag_clear

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

NAME
     vm_page_aflag_clear, vm_page_aflag_set, vm_page_reference -- change page atomic flags

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

     void
     vm_page_aflag_clear(vm_page_t m, uint8_t bits);

     void
     vm_page_aflag_set(vm_page_t m, uint8_t bits);

     void
     vm_page_reference(vm_page_t m);

DESCRIPTION
     The vm_page_aflag_clear() atomically clears the specified bits on the page's aflags.

     The vm_page_aflag_set() atomically sets the specified bits on the page's aflags.

     The vm_page_reference(m) call is the same as

	   vm_page_aflag_set(m, PGA_REFERENCED);

     and is the recommended way to mark the page as referenced from third-party kernel modules.

     These functions neither block nor require any locks to be held around the calls for correctness.

     The functions arguments are:

     m	   The page whose aflags are updated.

     bits  The bits that are set or cleared on the page's flags.

     The following aflags can be set or cleared:

     PGA_REFERENCED  The bit may be set to indicate that the page has been recently accessed.  For instance, pmap(9) sets this bit to reflect the
		     accessed attribute of the page mapping typically updated by processor's memory management unit on the page access.

     PGA_WRITEABLE   A writeable mapping for the page may exist.

     Both PGA_REFERENCED and PGA_WRITEABLE bits are only valid for the managed pages.

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

BSD
								  August 31, 2011							       BSD