Enable both sbrk(2)- and mmap(2)-based memory acquisition methods by

default.  This has the disadvantage of rendering the datasize resource
limit irrelevant, but without this change, legitimate uses of more
memory than will fit in the data segment are thwarted by default.

Fix chunk_alloc_mmap() to work correctly if initial mapping is not
chunk-aligned and mapping extension fails.

1 files changed, 12 insertions, 12 deletions

diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3
index 7138ead..466accc 100644
--- a/lib/libc/stdlib/malloc.3
+++ b/lib/libc/stdlib/malloc.3
@@ -32,7 +32,7 @@
 .\"     @(#)malloc.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd December 27, 2007
+.Dd January 3, 2008
 .Dt MALLOC 3
 .Os
 .Sh NAME
@@ -245,7 +245,7 @@ This option is not available for some configurations (non-PIC).
 Use
 .Xr mmap 2
 to acquire anonymously mapped memory.
-This option is disabled by default.
+This option is enabled by default.
 If both the
 .Dq D
 and
@@ -335,24 +335,24 @@ Traditionally, allocators have used
 to obtain memory, which is suboptimal for several reasons, including race
 conditions, increased fragmentation, and artificial limitations on maximum
 usable memory.
-This allocator uses
-.Xr sbrk 2
-by default in order to facilitate resource limits, but it can be configured at
-run time to use
+This allocator uses both
 .Xr sbrk 2
-and/or
-.Xr mmap 2 .
+and
+.Xr mmap 2
+by default, but it can be configured at run time to use only one or the other.
 If resource limits are not a primary concern, the preferred configuration is
 .Ev MALLOC_OPTIONS=dM
 or
 .Ev MALLOC_OPTIONS=DM .
 When so configured, the
 .Ar datasize
-resource limit has little practical effect for typical applications.
-The
+resource limit has little practical effect for typical applications; use
+.Ev MALLOC_OPTIONS=Dm
+if that is a concern.
+Regardless of allocator configuration, the
 .Ar vmemoryuse
-resource limit, however, can be used to bound the total virtual memory used by
-a process, as described in
+resource limit can be used to bound the total virtual memory used by a
+process, as described in
 .Xr limits 1 .
 .Pp
 This allocator uses multiple arenas in order to reduce lock contention for