VM_PAGE_AFLAG(9)       FreeBSD 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>.

FreeBSD 13.1-RELEASE-p6         August 31, 2011        FreeBSD 13.1-RELEASE-p6