From 320479713e9e05311dd631bcccc5a3cd71fc5721 Mon Sep 17 00:00:00 2001
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Tue, 2 May 2006 03:00:05 +0000
Subject: [PATCH] Document SHM_NORESERVE flag, new in 2.6.15.

---
 man2/shmget.2 | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/man2/shmget.2 b/man2/shmget.2
index b092cbb6f..4482ffe97 100644
--- a/man2/shmget.2
+++ b/man2/shmget.2
@@ -33,7 +33,7 @@
 .\"	Language and formatting clean-ups
 .\"	Added notes on /proc files
 .\"
-.TH SHMGET 2 2005-10-26 "Linux 2.6.14" "Linux Programmer's Manual"
+.TH SHMGET 2 2006-05-02 "Linux 2.6.15" "Linux Programmer's Manual"
 .SH NAME
 shmget \- allocates a shared memory segment
 .SH SYNOPSIS
@@ -110,12 +110,28 @@ argument of
 .BR open (2).
 Presently, the execute permissions are not used by the system.
 .TP
-.B SHM_HUGETLB
+.BR SHM_HUGETLB " (since Linux 2.6)"
 Allocate the segment using "huge pages."  
 See the kernel source file
 .I Documentation/vm/hugetlbpage.txt
 for further information.
-.\" FIXME 2.6.15 adds SHM_NORESERVE; document it.
+.TP
+.BR SHM_NORESERVE " (since Linux 2.6.15)"
+This flag serves the same purpose as the
+.BR mmap (2)
+.B MAP_NORESERVE
+flag.
+Do not reserve swap space for this segment. 
+When swap space is reserved, one has the guarantee
+that it is possible to modify the segment.
+When swap space is not reserved one might get SIGSEGV upon a write
+if no physical memory is available.
+See also the discussion of the file
+.I /proc/sys/vm/overcommit_memory
+in 
+.Br proc (5).
+.\" As at 2.6.17-rc2, this flag has no effect if SHM_HUGETLB was also
+.\" specified.
 .PP
 When a new shared memory segment is created,
 its contents are initialised to zero values, and