madvise.2: Document MADV_DONTDUMP and MADV_DODUMP

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/madvise.2

@@ -32,7 +32,7 @@
 .\" 2011-09-18, Doug Goldstein <cardoe@cardoe.com>
 .\"     Document MADV_HUGEPAGE and MADV_NOHUGEPAGE
 .\"
-.TH MADVISE 2 2011-09-18 "Linux" "Linux Programmer's Manual"
+.TH MADVISE 2 2012-04-28 "Linux" "Linux Programmer's Manual"
 .SH NAME
 madvise \- give advice about use of memory
 .SH SYNOPSIS
@@ -247,6 +247,24 @@ Ensures that memory in the address range specified by
 and
 .IR length
 will not be collapsed into huge pages.
+.TP
+.BR MADV_DONTDUMP " (since Linux 3.4)"
+Exclude from a core dump those pages in the range specified by
+.I addr
+and
+.IR length .
+This is useful in applications that have large areas of memory
+that are known not to be useful in a core dump.
+The effect of
+.BR MADV_DONTDUMP
+takes precedence over the bit mask that is set via the
+.I /proc/PID/coredump_filter
+file (see
+.BR core (5)).
+.TP
+.BR MADV_DODUMP " (since Linux 3.4)"
+Undo the effect of an earlier
+.BR MADV_DONTDUMP .
 .SH "RETURN VALUE"
 On success
 .BR madvise ()
@@ -356,4 +374,5 @@ from the system call, as it should).
 .BR mmap (2),
 .BR mprotect (2),
 .BR msync (2),
-.BR munmap (2)
+.BR munmap (2),
+.BR core (5)