Module Name: src
Committed By: martin
Date: Mon Jul 31 16:02:32 UTC 2023
Modified Files:
src/lib/libc/sys [netbsd-10]: mremap.2
Log Message:
Pull up following revision(s) (requested by riastradh in ticket #274):
lib/libc/sys/mremap.2: revision 1.9
mremap(2): Note MAP_REMAPDUP bug.
To generate a diff of this commit:
cvs rdiff -u -r1.7.12.1 -r1.7.12.2 src/lib/libc/sys/mremap.2
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/sys/mremap.2
diff -u src/lib/libc/sys/mremap.2:1.7.12.1 src/lib/libc/sys/mremap.2:1.7.12.2
--- src/lib/libc/sys/mremap.2:1.7.12.1 Mon Jul 31 15:52:44 2023
+++ src/lib/libc/sys/mremap.2 Mon Jul 31 16:02:32 2023
@@ -1,4 +1,4 @@
-.\" $NetBSD: mremap.2,v 1.7.12.1 2023/07/31 15:52:44 martin Exp $
+.\" $NetBSD: mremap.2,v 1.7.12.2 2023/07/31 16:02:32 martin Exp $
.\"
.\" Copyright (c) 2007 Thomas Klausner and Joerg Sonnenberger
.\" All rights reserved.
@@ -231,3 +231,36 @@ system call appeared in
It was based on the code that supports
.Fn mremap
compatibility for Linux binaries.
+.Sh BUGS
+If a mapping is created by
+.Xr mmap 2
+with
+.Dv MAP_PRIVATE
+and then duplicated by
+.Nm
+with
+.Dv MAP_REMAPDUP ,
+calling
+.Xr fork 2
+destroys the coupling between the original and duplicate mapping.
+Workarounds:
+.Bl -dash
+.It
+Create the original mapping with
+.Dv MAP_SHARED .
+.It
+Use
+.Xr minherit 2
+with
+.Dv MAP_INHERIT_NONE
+on the writable mapping.
+.It
+Don't use
+.Xr fork 2 ;
+use
+.Xr posix_spawn 2 .
+.El
+.Pp
+See
+.%U https://gnats.NetBSD.org/55177
+for details.
